Advanced autopilot design with extremum-seeking control for aircraft control
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Haci Baran
und
Ismail Bayezit
Abstract
The aim of this research is to enhance adaptive autopilots for the effective management of aircraft systems, control maintenance, and the rejection of external disturbances. To achieve this objective, we propose the design of an autopilot integrated with the extremum-seeking control (ESC) algorithm. Although autopilots proficiently manage the lateral and longitudinal modes of aircraft control, they lack filtering or adaptive capabilities, thereby exposing the system to significant external threats. To mitigate these risks, the ESC method is employed. This adaptive approach can operate in a disturbance rejection manner by adjusting parameters for unknown inputs and restoring the system to its original controlled response. ESC represents a versatile control method suitable for effective application in simulations or experimental models. Through the incorporation of this method, the pitch attitude hold autopilot, altitude hold autopilot, and yaw autopilot acquire advanced disturbance rejection capabilities with adaptive ESC features. The novelty of the proposed method lies in providing advanced disturbance rejection properties to conventional autopilots, thereby rendering them innovative and superior disturbance rejection controllers. The newly developed autopilots are capable of eliminating severe disturbances from the system response, including ramp, sinusoidal, and step disturbances. The integration of autopilots with ESC offers significant advantages, such as superior disturbance rejection properties for the aircraft unmanned aerial vehicle (UAV) system. The proposed method successfully eliminates severe disturbances, as demonstrated in simulation results, surpassing previous methods in effectiveness. Furthermore, the Autopilot-ESC method enhances aircraft operation even under disturbances, minimizing energy consumption and ensuring stability and control. This novel method reduces operator workload and ensures reliable and efficient autonomous flight capabilities. Additionally, the adaptability of the Autopilot-ESC to changing environmental conditions make it well-suited in aircraft UAVs. This upgraded version of autopilot surpasses other robust controllers, such as Linear Quadratic Gaussian (LQG) regulator and Model Predictive Control (MPC), as it can effectively address ramp, sinusoidal, and step disturbances, which LQG and MPC cannot handle.
1 Introduction
Unmanned aerial vehicles (UAVs) present numerous advantages over conventional aircraft. By lacking human passengers, accidents involving these compact aircraft do not result in human fatalities. Furthermore, UAVs obviate the necessity for a pilot, thereby enabling them to proficiently undertake arduous and perilous tasks. Additionally, UAVs are characterized by their lightweight construction and the capacity to operate continuously for prolonged durations without interruption. In recent years, UAVs have undergone significant advancements and are now extensively deployed across various domains including military operations, surveillance, transportation, wildfire suppression, and more, particularly in hazardous environments. The efficacy of UAV missions crucially depends on the implementation of effective and dependable control methodologies. However, developing a control system for such aerial applications presents a formidable challenge due to their extensive and irregular flight envelopes. Safety emerges as a paramount concern in the aeronautical industry, particularly for UAVs, which are increasingly employed in critical missions.
Small UAVs have garnered significant popularity owing to their portability, cost-effectiveness, and capacity to undertake challenging tasks, notably critical location monitoring. Nonetheless, their diminutive size, limited strength, and low weight render them susceptible to diverse external and internal factors such as faults, disturbances, and sensor malfunctions. These factors can adversely affect the flight performance, stability, and overall quality of UAVs. Designing a flight control system for small UAVs constitutes a complex endeavor requiring the mitigation of external disturbances and consideration of the impact of unknown factors. Given that small UAVs can operate for extended durations without human pilots, the development of disturbance rejection control systems is imperative to ensure safe and reliable operations, particularly crucial during winter when rapid climatic changes can pose challenges during prolonged flight missions. Numerous studies have been conducted to investigate the influence of external disturbances on the flight performance of miniature UAVs. By comprehensively analyzing the effects of various factors, including disturbances, the design and implementation of robust control systems can augment the reliability and effectiveness of small UAVs across diverse operational scenarios. Shen and Xu [1], to enable the unmanned helicopter to fly autonomously in precise paths and reduce the influence of internal and external unknown disturbances of the unmanned helicopter, proposed the adaptive radial basis function neural network-based active disturbance rejection controller (ADRC). In the study by Labbadi and Cherkaoui [2], to achieve fast speed and high accuracy performances for the quadrotor UAV, an adaptive fractional-order nonsingular fast terminal sliding mode controller (SMC) is proposed. Liu et al. [3] focused on path‐following control for small fixed‐wing UAVs under wind disturbances. Lai and Le [4] presented the development of an autonomous flight control system for a small-scale unmanned helicopter based on an online adaptive learning-based observer and model predictive control (MPC). He et al. [5] proposed a sliding mode-based nonlinear control scheme for the hovering flight of a tilt tri-rotor UAV, consisting of position control, attitude control, and control allocation. In the study by Lanzon et al. [6], the problem of designing a control law in case of rotor failure in quadrotor vehicles is addressed. In the study by Kumar et al. [7], the conceptual design and flight controller of a novel kind of quadcopter are presented. This design is capable of morphing the shape of the UAV during flight to achieve position and attitude control. Shin et al. [8] presented nonlinear disturbance observer-based standoff tracking guidance for multiple small fixed-wing UAVs in the presence of wind. Furthermore, Eliker and Zhang [9] presented a reliable and novel quadrotor flight control system designed to enhance trajectory tracking performance, robustness, and adaptiveness against the uncertain parameters and the external wind disturbance. Wu and Mueller [10] proposed a method for finding the optimal speed and heading of a multicopter when flying a given path to achieve the longest flight range. The design of a nonlinear robust controller for a non-minimum phase model of an air-breathing hypersonic vehicle is presented by Fiorentini and Serrani [11]. A study of nonlinear robust adaptive control of flexible air-breathing hypersonic vehicles is reported by Fiorentini et al. [12]. A robust nonlinear control method for a hypersonic aircraft is presented by Wang and Stengel [13]. Seferian and Bazzi [14] proposed a method based on extremum-seeking control (ESC) for the detection of four major types of faults that occur in induction motors. An integrated approach to the fault-tolerant control (FTC) of a quadcopter UAV with incipient actuator faults is presented by Kantue and Pedro [15]. Vandermeulen et al. [16] proposed a discrete-time version of ESC which can be implemented by several agents communicating over a network. In the study by Sahneh et al. [17], an extremum seeking algorithm is proposed for mappings where the optimal point is time-varying. Oliveira et al. addressed the design and analysis of multi-variable extremum seeking for static maps subject to arbitrarily long time delays [18]. Xie et al. considered the problem of designing nonlinear robust formation controllers on a team of UAV using off-the-shelf autopilots [19]. Binetti et al. presented a comprehensive design procedure based on extremum seeking for minimum power demand formation flight, the first with performance guarantees [20]. Lavretsky et al. focused on an adaptive output-tracking problem using on-line extremum seeking command generation [21]. An ESC algorithm was defined for discrete-time systems which implemented to a group of plants [22]. A type 2 fuzzy logic PID controller is proposed for twin rotor mimo system control problem in the study by Zeghlache et al. [23]. Krause reported on the latest results concerning the active noise control approach using net flow of acoustic energy [24]. Gheni et al. explored the use of DRL for controlling vibrations in building structures. Specifically, they focused on the problem of reducing vibrations induced by external sources such as wind or earthquakes [25].
Disturbance rejection control in UAVs stands as a forefront research area essential for enhancing UAV autonomy, resilience, and mission effectiveness. UAVs operate in diverse and dynamic environments, encountering disturbances such as gusts, wind shear, and atmospheric turbulence that can significantly affect their stability and performance. Current research focuses on developing sophisticated control algorithms and adaptive strategies to effectively counteract disturbances and maintain desired flight trajectories. In recent years, significant strides have been made in the utilization of robust control techniques such as adaptive control, predictive control, H-infinity control, SMC, and active disturbance rejection control, offering disturbance rejection capabilities. Moreover, the integration of machine learning and data-driven methods has emerged as a promising frontier, enabling the development of adaptive controllers capable of learning from real-time data streams to adaptively reject disturbances. The following journal descriptions mention some studies of last 3 years about disturbance rejection of UAVs.
The authors present an integral backstepping active disturbance rejection control strategy for quadrotor UAV attitude control, featuring a novel smooth function newfal
This study presents a comprehensive design approach for an advanced autopilot system. The autopilot system employed in this research comprises two distinct control components, each fulfilling a specific function. The first component aims to ensure system stability and control by effectively regulating the system’s behavior and maintaining the desired performance criteria. In contrast, the second component is dedicated to adapting the system parameters in response to external disturbances that may affect the system’s performance. This adaptive parameter adjustment mechanism enables the autopilot to promptly identify and mitigate the effects of such disturbances, thereby ensuring that the system response remains within acceptable bounds and restoring the desired performance characteristics.
The novelty of the proposed method lies in its integration of the ESC algorithm with conventional autopilots to provide them advanced disturbance rejection properties. Unlike traditional autopilots, which lack adaptive, disturbance rejection capabilities, this approach utilizes ESC’s dynamic parameter adjustment to effectively mitigate unknown inputs and restore the system to its original controlled response, thereby enhancing resilience against external threats. By incorporating ESC features into autopilot systems such as pitch attitude hold autopilot, altitude hold autopilot, and yaw autopilot, the resulting integration yields innovative disturbance rejection controllers capable of eliminating severe disturbances, such as ramp, sinusoidal, and step disturbances. Notably, this integration offers superior disturbance rejection compared to previous methods, as demonstrated by simulation results, thereby enhancing aircraft operation under disturbances while minimizing energy consumption and reducing operator workload. For instance, the Linear Quadratic Gaussian Regulator (LQG) and MPC fail to mitigate harsh disturbances, whereas our proposed method successfully rejects these disturbances, as evidenced by the simulation results.
This work follows a systematic structure. Section 1 begins with an introductory section that provides an overview of the research topic and its significance in the field. Section 2 is dedicated to clearly defining the problem statement, establishing specific challenges, and outlining the objectives addressed in the study. The mathematical formulation of the nonlinear equations governing the dynamics of the aircraft UAV is presented in Section 3, laying the groundwork for further analysis. Progressing to Section 3.3, the autopilot structure is detailed, offering insights into the design principles and control strategies applied. Section 5 presents simulations conducted to validate and assess the performance of the proposed autopilot system. Finally, Section 6 engages in the discussion of findings and results, drawing conclusions based on the analysis conducted throughout the study in Section 7.
2 System model
2.1 Problem statement
Managing small UAVs during extended and high-risk missions can present challenges, given the potential hazards of collisions and severe disturbances. Hence, it is imperative to develop control systems that exhibit robustness and reliability. In this study, an autopilot system has been developed to adeptly regulate the dynamics of the UAV and maintain stability. However, recognizing the challenging environmental conditions, additional measures may be necessary to optimize the system’s performance. To address these challenges, an ESC approach has been implemented, aiming to mitigate the risks associated with crashes and adverse weather. This adaptive autopilot system can adjust to inputs and varying system parameters. Through the implementation of a cascaded control system, the primary objective is to ensure the stability and precise control of the UAV throughout its operations.
Figure 1 illustrates the structural features of a fixed-wing UAV model, providing a visual representation of its key characteristics. Additionally, it graphically depicts the external forces and moments affecting the UAV, along with the velocity components that govern its motion. The figure also includes an illustration emphasizing the potential impact of disturbances, which have the capacity to adversely affect the overall performance and operation of the aircraft system.
Fixed-wing UAV model exposed to disturbance.
2.2 Nonlinear system dynamics
This section offers a synopsis of the nonlinear and linear equations governing the dynamics of small UAVs. Due to their substantial number, a detailed analysis of each equation is not undertaken here. However, for readers seeking a deeper understanding, reference to Chapter 3 of the study by Beard and McLain [33] is recommended, as it extensively explores these dynamics. Furthermore, Chapter 4 of their study [33] specifically focuses on equations related to forces and moments, while Chapter 5 delves into the intricacies of the trim and linearization process, providing valuable insights into the dynamics of small UAVs.
2.2.1 Forces and moments equations
The equations for forces and moments can be succinctly summarized in the following matrix system. To represent the entire equation in a single horizontal line, the force equations in [33] are expressed using the following equality:
where
where
To express the moment equations in a concise and single horizontal line, the following equality is utilized:
where the variables
2.2.2 Equations of motion
The matrix system presented below provides a concise representation of the aircraft’s equations of motion, incorporating a total of 12 aircraft states, as evident from the formulation.
where
In this specific context, the symbols
2.2.3 Model linearization
The equations governing an aircraft’s motion in six degrees of freedom inherently display nonlinearity, introducing complex dynamics that can pose challenges in control system design. Nevertheless, it is a common practice to linearize the nonlinear model of fixed-wing UAVs for the ease of designing and analyzing control systems. This linearization procedure transforms the system into a linear model, simplifying control design and rendering it more amenable to classical control techniques.
The dynamics of a fixed-wing UAV can be categorized into two primary modes: the longitudinal mode and the lateral mode. The longitudinal mode focuses on variables such as airspeed, pitch angle (theta), and altitude, which are crucial for controlling the UAV’s forward motion and climb/descent. Conversely, the lateral mode involves roll angle (phi) and yaw angle (psi), determining the UAV’s lateral movements and heading changes. In the field of flight dynamics, the concept of trim plays a significant role in UAV control. Trim entails achieving a state of force and moment equilibrium, where the sum of all forces and moments acting on the aircraft is balanced, resulting in a stable flight path without constant pilot input. This trim condition is essential for various flight phases, including straight-and-level flight, climbing, and turning. By attaining trim, the UAV can maintain a desired flight attitude and path, thereby enhancing overall flight stability and efficiency.
In the process of designing control systems, it is crucial to comprehend and consider both the longitudinal and lateral modes, as well as the concept of trim. The linearized model provides a simplified representation of the UAV’s behavior, enabling control engineers to develop feedback controllers that stabilize and regulate the aircraft’s motion. By integrating appropriate control strategies, the UAV can achieve desired flight trajectories and effectively perform various tasks, such as aerial surveillance, mapping, payload delivery, and environmental monitoring. As the UAV industry advances, the development of sophisticated control algorithms and navigation systems will play a pivotal role in enhancing the safety, efficiency, and versatility of UAVs across a wide range of applications.
2.2.3.1 Trim conditions
The illustration of nonlinear systems is depicted in the following manner:
The variables
The equilibrium condition is expressed as follows: This condition delineates the stable state wherein the system’s state variables and inputs persist without change over time, thereby indicating a state of balance or stability.
In this context, the variables
Under the trim condition, the UAV achieves a state of equilibrium with balanced forces and moments. And the subsequent relation is fulfilled, indicating the successful attainment of stable flight conditions.
In the calculation process to determine trim states, it is imperative to satisfy and uphold the prescribed set of conditions. These conditions are crucial for ensuring the stability and equilibrium of the analyzed system.
Constant Speed
Climbing at constant flight path angle
Constant orbit of radius
The positions, velocities, Euler angles, and roll, pitch, and yaw rates are individually presented according to the study by Beard and McLain [33]. This representation elucidates the specific values corresponding to each of the mentioned state variables, facilitating a comprehensive understanding of the system’s dynamics.
The control surfaces, namely, elevator, throttle, aileron, and rudder deflections, specific to the fixed-wing UAV, are individually depicted as provided below. These representations offer a comprehensive view of the orientation and configuration of each control surface, which is critical for understanding the UAV’s control system.
As a consequence of the trim conditions, the following equalities, as referenced in the study by Beard and McLain [33], are utilized. These equalities play a significant role in establishing and maintaining the stable and balanced state of the UAV during operation.
The turn rate constant, as referenced in the study by Beard and McLain [33], is explicitly presented below. This critical constant determines the UAV’s ability to perform turning maneuvers and plays a pivotal role in the analysis of its turning dynamics.
As indicated by Beard and McLain [33], the climb rate constant is denoted below. This essential constant governs the rate of vertical ascent or descent of the UAV, playing a pivotal role in assessing its vertical flight characteristics.
As mentioned by Beard and McLain [33], the state variable
As indicated by Beard and McLain [33], the longitudinal state space model is presented below. This model provides a detailed mathematical representation of the UAV’s longitudinal dynamics, serving as a valuable tool for analyzing its motion and stability characteristics in the longitudinal plane.
The lateral state space model, as presented by Beard and McLain [33], is illustrated below. This model provides a detailed mathematical depiction of the UAV’s lateral dynamics, enabling a comprehensive examination of its motion and stability characteristics in the lateral plane.
where
3 ESC
ESC is an adaptive control algorithm that has been previously discussed in the literature. This method proves particularly advantageous when confronted with scenarios that lack precise knowledge of system dynamics and the mappings between control parameters and an objective function. The versatility of extremum seeking extends beyond a single application area, as it can effectively optimize parameters in dynamic systems and tackle static optimization problems alike. The core strength of ESC lies in its adaptive nature, enabling autonomous convergence towards an optimal solution through iterative adjustments of control parameters based on real-time measurements and feedback. This inherent adaptability renders it well-suited for systems with time-varying dynamics, where traditional control approaches may prove insufficient or impractical. Moreover, ESC has found applications in various domains, spanning from aerospace and robotics to power systems and industrial processes. In aerospace, for instance, it optimizes aircraft control parameters, enhancing performance and fuel efficiency. In robotics, ESC fine-tunes robotic manipulator parameters, improving task performance and precision. Additionally, it optimizes the operation of distributed energy resources and stabilizes grid dynamics in power systems. The effectiveness of extremum seeking stems from its ability to efficiently search for the optimal operating point without necessitating extensive system modeling or exhaustive exploration of the parameter space. Instead, it relies on local measurements and feedback to iteratively update control parameters, effectively seeking the extremum (maximum or minimum) of a given objective function.
In summary, ESC emerges as a powerful and versatile technique adept at adapting to diverse applications and problem domains. Its capability to optimize control parameters in dynamic systems renders it a valuable tool for enhancing performance, efficiency, and stability across a broad spectrum of engineering and scientific disciplines.
The process of tuning a parameter value using the extremum seeking algorithm comprises four distinct stages. These stages constitute a systematic approach to iteratively optimize the parameter and attain the desired extremum (maximum or minimum) of the objective function.
Stage #1. Within the extremum seeking algorithm, a specific stage, referred to as modulation, involves the application of a low-amplitude sinusoidal signal to perturb the parameter value under optimization. This modulation process aids in gathering information about the system’s response to perturbations, facilitating the determination of the optimal parameter value corresponding to the desired extremum of the objective function.
Stage #2. System Response – As the optimized system encounters perturbations in the parameter, it responds accordingly, leading to a corresponding alteration in the value of the objective function. This interaction between the perturbations and the objective function offers valuable feedback to the extremum seeking algorithm, aiding it in refining the parameter value towards the optimal extremum.
Stage #3. Demodulation – In this stage of the extremum seeking algorithm, the objective function signal undergoes multiplication by a sinusoidal signal with the same frequency as that of the modulation signal. The aim of this step is to leverage sinusoidal modulation and extract valuable information about the system’s response to perturbations. To alleviate potential bias in the objective function signal, a high-pass filter can be optionally employed, thereby enhancing the accuracy of the optimization process.
Stage #4. Parameter Update – During the updating process, the parameter value undergoes adjustment through an integrator that receives the demodulated signal. The state of the integrator can be toggled between on and off, thereby influencing the rate of parameter adaptation. In some cases, a low-pass filter is employed to counteract high-frequency noise present in the demodulated signal, enhancing the accuracy of the parameter tuning.
3.1 Optimization of static systems
Figure 2 illustrates the application of extremum seeking for addressing a static optimization problem. This involves optimizing certain parameters within the system to achieve the desired extremum (maximum or minimum) of the objective function, thus demonstrating the effectiveness of the extremum seeking technique in such scenarios.
ESC block diagram.
In the subsequent sections, the ESC problem under consideration will be formally defined, based on the following set of assumptions. These assumptions lay the foundation for the subsequent analysis and investigation of the problem at hand.
A.1. In this context, the estimation of the parameter value is denoted as
A.2. The output of the function being maximized, referred to as the objective function, is represented by the equation
A.3. The frequency at which both the modulation and demodulation signals are applied is denoted as
A.4. The modulating signal is denoted as
A.5. The learning rate of the autopilot is symbolized as
A.6. The optimal parameter value, denoted as
In cases where multiple parameters require optimization, employing a distinct tuning component for each parameter is essential. This approach ensures that each parameter is independently adjusted and fine-tuned to reach its optimal value within the system, thereby contributing to a comprehensive and efficient optimization process.
In Figure 3, we depict the practical implementation of extremum seeking, emphasizing a rising segment of the objective function curve. The modulation signal, in conjunction with the current parameter estimate, yields the modulated signal denoted as
The application of extremum seeking aiming to optimize a rising segment of the curve representing the objective function.
In Figure 4, we present the practical implementation of extremum seeking, demonstrating its utility in optimizing a decreasing segment of the objective function curve. By employing the modulation signal alongside the current parameter estimate, we derive the modulated signal
The utilization of ESC to optimize a particular section of the objective function curve.
In Figure 5, we illustrate the practical application of extremum seeking on a plateau of the objective function curve, representing a vicinity near the maximum. In this scenario, employing
Utilizing ESC on a level section of the objective function curve.
3.2 Perturbation based ESC
In this section, we examine the sinusoidal perturbation method, which stands as the most widely utilized approach for ESC. Renowned for its efficacy, this method facilitates rapid adaptation and straightforward implementation, particularly when addressing gradient-type problems. The primary foundation for this discourse can be traced back to Chapter 3 of the study by Zhang and Ordóñez [34], which serves as a fundamental resource for exploring and comprehending the intricacies of the sinusoidal perturbation technique. The application of this method assumes a pivotal role in numerous fields, including aerospace, robotics, and power systems, where optimization and control are of paramount importance. By harnessing continuous sinusoidal modulation and sophisticated algorithms, ESC with sinusoidal perturbation presents a versatile and robust tool for addressing complex optimization challenges.
Consider the optimization process of a performance function represented as
Sinusoidal perturbation based analog optimization.
For the extremum-seeking problem, the following assumptions are posited. These assumptions function as foundational premises for the subsequent analysis and investigation of the optimization process.
Assumption 1
There exists a smooth function
Assumption 2
There exists
Hence, we deem the output equilibrium map as a fundamental assumption for this study. This assumption forms the basis for the subsequent analysis:
has a maximum at
Theorem 1
Provided the appropriate system size,
Figure 6
illustrates a singular exponentially stable periodic solution with a period of
The theorem presented in this context establishes a property of local convergence in continuous perturbation-based optimization of single-parameter functions. This result signifies the system’s capacity to converge toward a local optimal solution through continuous perturbations and is crucial for analyzing the effectiveness and reliability of such optimization techniques. The output
In this investigation, Figure 6 provides an illustrative representation of the ESC scheme, a methodology predicated upon analog optimization and reliant upon perturbations. In order to broaden the applicability of perturbation-based ESC to moderately unstable systems, particularly addressing the challenge of autonomous vehicle source seeking, we derive valuable insights from the findings outlined in Chapter 3 of the study by Zhang and Ordóñez [34]. By employing sophisticated methodologies including averaging and singular perturbation, our research demonstrates the convergence of closed-loop system solutions toward a narrow vicinity encompassing the extremum of the equilibrium map. This vicinity diminishes in scale as the adaptation gain, frequency, and amplitude of the periodic signal employed for extremum seeking increase, adhering to an inverse relationship. Although not a mandatory component, the incorporation of a low-pass filter
In the context of this study, we denote
The initial analysis focuses on the static case, wherein the variable
Perturbation based ESC.
The subsequent theorem establishes a formal mathematical proposition.
Theorem 2
[34]: Assuming that the feedback system (22) and (23) satisfies Assumptions 1–2, it becomes feasible to identify a set of initial conditions centered at the point
3.3 Advanced autopilot
In this section, we designed novel, adaptive autopilots by integrating ESC algorithm to them. This new autopilot structure has innovative disturbance rejection properties.
The innovative structure of the autopilots we have developed represents a novel approach in the realm of autopilots and disturbance rejection controllers. We have successfully integrated autopilot systems with the ESC algorithm, introducing unique disturbance rejection properties to the autopilots. This integration marks a pioneering advancement in disturbance rejection. Moreover, our method exhibits superior disturbance rejection capabilities compared to other existing approaches. Specifically, our proposed method can effectively reject severe disturbances that other methods struggle to address. The efficacy and superiority of our approach over previous methods are evident in the comparative analysis presented in Section 5. Our method is rigorously compared with well-established methods such as LQG and MPC. Examining the error functions depicted in the figures, it is apparent that our proposed method demonstrates significantly lower error levels when compared to the LQG and MPC methods. Additionally, the tables presenting Root mean square error (RMSE) values further substantiate the effectiveness and superiority of our proposed method. The RMSE values for our method are notably smaller than those associated with other methods, underscoring the enhanced performance and robustness of our approach.
Figure 8 shows fixed-wing UAV flight operation by utilizing autopilot-ESC integration under external disturbances. The fixed-wing UAV is controlled by conventional autopilot under normal conditions. However, when it is exposed to external disturbances ESC algorithm is utilized to reject them and provide safety during flight operations.
Flowchart for Autopilot-ESC integration control under disturbances.
In the research methodology, the calibration and validation of the tools, specifically the autopilots integrated with the ESC algorithm, represent pivotal stages in ensuring the effectiveness and reliability of the proposed system. Calibration entails the precise adjustment of autopilot parameters and the ESC algorithm to optimize their performance and ensure compatibility. This procedure guarantees that the proposed autopilots accurately respond to control inputs and external disturbances, thereby augmenting their adaptive capabilities. Parameters of both the autopilots and the ESC algorithm were meticulously adjusted to ensure stability, control, and disturbance mitigation. Detailed information regarding the tuned parameters is provided in Sections 4, 4.1, and 4.2.
Validation, on the other hand, entails comparing the integrated autopilot-ESC system with previous control methods possessing disturbance rejection properties through simulations to verify its functionality under various disturbances. In this study, we compared our proposed method with LQG and MPC for validation. As evident from the comparative analysis of the simulation results, the proposed method performs effectively and exhibits superiority over LQG and MPC. Ultimately, the calibration and validation processes contribute to the development of advanced disturbance rejection autopilots capable of ensuring safe and reliable autonomous flight operations in UAVs.
As the proposed method is compared with LQG and MPC in this study, defining the calibration/validation of the tools employed in the research methodology necessitates the provision of the following adjusted controller parameters:
LQG tuned parameters for longitudinal theta angle control were determined as follows:
LQG tuned parameters for longitudinal altitude control were determined as follows:
LQG tuned parameters for lateral psi angle control were determined as follows:
For longitudinal and lateral control, tuned parameters of MPC were determined as given below:
Elevator and rudder were scaled as
Upper limits for plant outputs are named as scale factor:
MPC weights are dimensionless and applied to the scaled MV and OV values. The weight scales are as follows:
where MV represents the manipulated variables and OV denotes the output variables.
In the subsequent subsections, explanations of pitch attitude hold, altitude hold, and yaw autopilots are provided. Subsequently, the integration of the ESC algorithm with these autopilots is illustrated in Figures 9–11, respectively.
The improved pitch attitude hold autopilot block diagram.
The improved altitude hold autopilot block diagram.
The improved yaw autopilot block diagram.
4 Adaptive pitch attitude hold autopilot
The pitch attitude hold autopilot, also known as the pitch hold mode or altitude hold mode, represents a ubiquitous feature within aircraft autopilot systems. Its principal role is to autonomously sustain a specified pitch attitude or flight level, thereby enabling pilots to mitigate their workload and concentrate on other operational tasks. Upon activation, the pitch attitude hold autopilot system employs various sensors, including an attitude indicator, altimeter, and airspeed indicator, to ascertain the present pitch attitude and altitude of the aircraft. Subsequently, it issues directives to the pertinent control surfaces, typically the elevators, to maintain the desired pitch attitude or altitude. Upon engagement, the autopilot system maintains the relationship θ = α + γ at its current value. This control mechanism ensures that the pitch angle (θ) remains equivalent to the sum of the angle of attack (α) and the flight path angle (γ), thereby contributing to stable flight conditions, as discussed in Chapters 7 and 8 of the study by Nelson [35] and Chapter 4 of the study by Stevens et al. [36].
The primary function of the pitch attitude hold autopilot is to stabilize the aircraft at a specific pitch angle, directly influencing its ascent, descent, or level flight. By doing so, it contributes to maintaining a consistent angle of attack, thereby reducing the need for continuous pilot intervention. Pitch attitude hold autopilot systems are widespread across various aircraft types, including commercial airliners, business jets, and general aviation aircraft. They offer significant advantages, particularly during cruise flight, where precise control of pitch attitude or altitude is essential for optimizing fuel efficiency, ensuring passenger comfort, and adhering to air traffic control instructions. It is crucial to emphasize that the operation of the autopilot system, including the pitch attitude hold mode, must strictly adhere to the aircraft’s operating manual and be conducted under appropriate flight conditions. Pilots must remain vigilant and be prepared to disengage the autopilot, assuming manual control when necessary.
The diagram depicted in Figure 9 illustrates the recently designed autopilot. The internal component is utilized to stabilize systems that are inherently unstable, thereby ensuring effective control. Furthermore, the external component integrates ESC to facilitate the system’s adaptation to disturbances. This methodology guarantees that, even in the presence of adverse external influences, the system can reliably return to a controlled state.
We used the transfer function between
We used the following parameter values for ESC for adaptive pitch attitude hold autopilot design:
Gain k = 0.00000015, initial value = 0.00001,
Transfer function for pitch attitude hold and altitude hold autopilots are as follows:
We used the following parameter values for pitch attitude hold autopilot design:
Actuator transfer function =
4.1 Adaptive altitude hold autopilot
The altitude hold autopilot, also referred to as altitude hold mode or altitude hold function, constitutes a fundamental component within aircraft autopilot systems. Its principal function is to automatically maintain a predetermined altitude, thereby enabling the pilot to alleviate their workload and focus on other flight-related tasks. Upon activation, the altitude hold autopilot system leverages various sensors, notably the altimeter and vertical speed indicator, to accurately determine the aircraft’s current altitude and vertical speed. Subsequently, it adjusts the aircraft’s control surfaces and, where applicable, throttle settings to uphold the desired altitude, as elaborated in chapters 7 and 8 of [35] and chapter 4 of [36]. The primary aim of the altitude hold autopilot is to sustain the aircraft at a specified altitude, typically established by the pilot or programmed into the flight management system. This continuous maintenance of altitude facilitates compliance with air traffic control directives and diminishes the pilot’s workload during level flight.
Altitude hold autopilot systems integrate with other autopilot modes and sensors to achieve precise altitude control. These modes may include vertical speed control, flight level change, or vertical navigation modes, allowing for more sophisticated altitude management during climbs, descents, or transitions between altitudes. Additionally, certain altitude hold autopilot systems incorporate features such as altitude capture and altitude pre-select. Altitude capture facilitates a seamless transition from the current altitude to a selected one by automatically adjusting pitch and thrust. Conversely, altitude pre-select enables the pilot to input a desired altitude into the autopilot system, which the system will then capture and maintain upon engagement.
Altitude hold autopilot systems are prevalent in a wide array of aircraft, ranging from smaller general aviation planes to larger commercial airliners. Their utility is particularly pronounced during cruise flight, where the ability to maintain a specific altitude is paramount for considerations such as fuel efficiency, compliance with air traffic control instructions, and overall flight management.
As seen in Figure 10, we developed a new autopilot structure. We used the transfer function between
We used the following parameter values for ESC for adaptive altitude hold autopilot design:
Gain k = 0.000005, initial value = 0.00005,
Transfer function for Altitude Hold is the same as pitch attitude hold autopilot and is given below:
We used the following parameter values for Altitude Hold Autopilot design:
Actuator transfer function =
For
4.2 Adaptive yaw autopilot
Autopilot systems generally lack a specific “yaw autopilot” mode primarily because the aircraft’s yaw control is traditionally managed by the rudder, predominantly operated by the pilot or through coordinated flight control inputs. Yaw denotes the rotation of the aircraft around its vertical axis, influencing its heading or direction. Yaw control is vital for sustaining coordinated flight, particularly during turns or when contending with crosswinds. Although certain aircrafts feature yaw stability and control augmentation systems, these are not typically termed “yaw autopilot” systems. Instead, they assist in preserving yaw stability and mitigating adverse yaw effects under specific flight conditions, yet they do not fully automate the aircraft’s yaw control. Autopilot systems primarily focus on pitch and roll control, which encompasses altitude maintenance, airspeed, and navigation guidance. Nevertheless, they indirectly influence yaw control by maintaining the desired heading or track through coordinated roll inputs and sustaining a consistent bank angle during turns.
In conclusion, while autopilot systems typically do not incorporate a specialized “yaw autopilot” mode, they nonetheless play a significant role in maintaining coordinated flight and indirectly influence yaw control through their diverse operational modes, as elaborated in chapters 7 and 8 of the study by Nelson [35] and chapter 4 of the study by Stevens et al. [36].
As illustrated in Figure 11, we developed a new adaptive autopilot structure. We used the transfer function between
We used the following parameter values for ESC for the newly adaptive yaw autopilot design:
Gain k = 0.0003, initial value = 0.00015,
Transfer function for Yaw Autopilot is as follows:
We used the following parameter values for Yaw Autopilot design:
For
where
Figures 9–11 depict the implemented autopilot employing the ESC algorithm. The incorporation of ESC enhances the autopilot’s effectiveness in mitigating external disturbances. The newly advanced autopilots exhibit exceptional performance in both optimal and adverse conditions, as evidenced by the simulation figures.
5 Simulation results
Within this section, the proposed method is utilized to govern the longitudinal and lateral modes of the UAV aircraft, as illustrated in Figures 9–11. In these figures, external negative input
The analysis and processing of data in this study were conducted using MATLAB (MathWorks, 2021), a widely employed software environment for scientific computing, numerical analysis, and data visualization. The selection of MATLAB was grounded in its robust capabilities for managing and analyzing complex datasets, performing statistical analyses, and facilitating result visualization. MATLAB was specifically employed for statistical tests, plot creation, and regression analyses. The choice of MATLAB as the analytical tool was pivotal in ensuring the accuracy and reliability of the results presented in this work [40].
The following simulation results were obtained by collecting figures of generations of our study. MATLAB was utilized for gathering these figures. The figures are original work outputs.
5.1 Longitudinal results
5.1.1 Adaptive pitch attitude hold results
In this section, noise, step, ramp, and sinusoidal disturbances were applied to the pitch angle of the fixed-wing UAV. Simulation results demonstrate that, whereas the conventional pitch attitude hold autopilot fails to reject the noise and disturbances, the proposed autopilot method successfully mitigates them. Step, ramp, and sinusoidal disturbances pose significant challenges for current control methods. Nonetheless, the proposed method exhibits notable performance improvements and effectively mitigates these harsh disturbances.
The poles set of transfer function is [−1.0139 + 2.4703i − 1.0139 − 2.4703i − 0.1196 + 0.7275i − 0.1196 − 0.7275i]. Given that all poles of the transfer function concerning the theta angle reside in the left half-plane, the system is deemed stable. The values for maximum overshoot, undershoot, and rise time are provided below. It is evident that due to the low-rise time, there is a notable increase in overshoot.
Overshoot: 24.627%, undershoot: −1.704%, and rise time: 0.649488 s.
Figures 12–14 depict the management of the theta angle in the presence of disturbances. The diagrams illustrate that while the pitch attitude hold autopilot technique operates effectively under normal conditions, it fails to yield satisfactory results in the presence of external disturbances. Step, sinusoidal, and white noise disturbances are applied through integration in Figures 12–14, and the resulting outcomes are observed. As depicted in the figures, the pitch attitude hold autopilot proves incapable of effectively rejecting disturbances. However, employing pitch attitude hold autopilot and ESC in integration yields favorable outcomes. The first channel of Figure 9 corresponds to the result of
Theta angle control under white noise disturbances.
Theta angle control under sinusoidal and white noise disturbances.
Theta angle control under step and white noise disturbances.
Figure 15 depicts the management of the theta angle in response to step disturbance and ramp disturbance. The diagrams clearly illustrate that the pitch attitude hold autopilot fails to attain satisfactory results when external ramp and step disturbances are introduced. However, employing the pitch attitude hold autopilot and ESC separately results in positive outcomes. In Figure 15, the first channel represents the result of
Theta angle control under ramp and step disturbances.
Figure 16 illustrates the management of the theta angle in response to step disturbance and white noise disturbance. The diagram clearly indicates that while the pitch attitude hold autopilot technique operates effectively under normal conditions, it fails to produce satisfactory results when external step and white noise disturbances are introduced. However, employing the pitch attitude hold autopilot and ESC separately leads to a favorable outcome. In Figure 16, the first channel represents the result of
Theta angle control under step, ramp, and white noise disturbances.
5.1.2 Adaptive altitude hold results
In Section 5.1.1, we introduced and applied various disturbances, including noise, step, ramp, and sinusoidal perturbations to the pitch angle of the fixed-wing UAV. Building upon this framework, the subsequent section extends these disturbances to the altitude control of the fixed-wing UAV. Simulation outcomes indicate that the conventional altitude hold autopilot fails to mitigate the influence of such disturbances. Conversely, our proposed autopilot method demonstrates robustness against these disturbances, effectively attenuating their effects. Step, ramp, and sinusoidal disturbances present considerable challenges for conventional control methodologies. Nonetheless, our proposed approach exhibits marked performance improvements and effectively mitigates these disruptive influences.
The poles set of transfer function is [−1.0139 + 2.4703i −1.0139 −2.4703i −0.1196 + 0.7275i − 0.1196 − 0.7275i]. Given that all poles of the transfer function governing altitude reside in the left half-plane, the system is deemed stable. The maximum overshoot, undershoot, and rise time values are provided below. Notably, the elevated rise time corresponds to a diminished overshoot.
Overshoot: 0.505%, undershoot: 1.999 %, and rise time: 25.168 s.
Figures 17–19 illustrate altitude management amidst disturbances. Under normal conditions, the altitude hold autopilot technique exhibits efficacy. However, its performance falters when confronted with external disturbances. The diagrams depict the ramifications of sinusoidal and white noise disturbances, as well as step disturbances introduced via integration. It is evident from the figures that the altitude hold autopilot struggles to adequately counteract and reject these disturbances. Nonetheless, employing the altitude hold autopilot and ESC separately yields favorable results. In Figure 17, the first channel depicts the
Altitude control under white noise disturbances.
Altitude control under sinusoidal and white noise disturbances.
Altitude control under step and white noise disturbances.
Figure 20 presents an overview of altitude management amidst step and ramp disturbances. The diagrams distinctly illustrate that the altitude hold autopilot fails to attain satisfactory results upon the introduction of external ramp and step disturbances. Nonetheless, employing the altitude hold autopilot and ESC separately yields positive outcomes. In Figure 20, the first channel illustrates the
Altitude control under ramp and step disturbance.
Figure 21 illustrates altitude control in the presence of step, ramp, and white noise disturbances. The diagram distinctly shows that the altitude hold autopilot technique performs effectively under normal conditions; however, it fails to produce satisfactory results when external step, ramp, and white noise disturbances are introduced. Nonetheless, employing the altitude hold autopilot and ESC separately leads to favorable outcomes. In Figure 21, the first channel depicts the
Altitude control under step, ramp, and white noise disturbances.
5.2 Lateral results
5.2.1 Adaptive yaw autopilot results
The poles set of transfer function is [−7.1547 − 2.9679 + 6.34495i − 2.9679 − 6.34495i 0.0805]. The instability of the system is indicated by the presence of a positive pole in the transfer function of the psi angle. The specific metrics characterizing system response are detailed below, encompassing maximum overshoot, undershoot, and rise time. Notably, the brief rise time is associated with a relatively elevated overshoot level.
Overshoot: 10.556%, undershoot: −5.071 %, and rise time: 0.019133 s.
Figures 22–24 present an overview of the management of the psi angle in the presence of disturbances. The diagrams elucidate that while the yaw autopilot technique proves effective under normal conditions, it falls short in delivering satisfactory results when encountering external disturbances. Step, sinusoidal, and white noise disturbances are introduced through integration in Figures 22–24, with subsequent recording of the observed outcomes. It is apparent from the figures that the yaw autopilot fails to sufficiently attenuate these disturbances. Conversely, employing the yaw autopilot and ESC separately yields favorable outcomes. In Figure 22, the first channel depicts the result of
Psi angle control under white noise disturbance.
Psi angle control under sinusoidal and white noise disturbances.
Psi angle control under step and white noise disturbances.
Figure 25 provides a visual representation of how the psi angle is managed in the presence of step and ramp disturbances. The diagrams vividly illustrate that the yaw autopilot fails to achieve satisfactory results when external ramp and step disturbances are introduced. However, employing the yaw autopilot and ESC separately yields favorable outcomes. In Figure 25, the first channel represents the result of
Psi angle control under step and ramp disturbances.
Figure 26 presents a visual representation of how the psi angle is managed in the presence of step, ramp, and white noise disturbances. The diagram clearly indicates that while the yaw autopilot technique operates effectively under normal conditions, it fails to achieve satisfactory results when external step, ramp, and white noise disturbances are introduced. However, employing the yaw autopilot and ESC separately leads to a favorable outcome. In Figure 26, the first channel represents the result of
Psi angle control under ramp and white noise disturbances.
5.3 Comparison of the proposed method with MPC and LQG methods to show the superiority
In this section, we conduct a comparative analysis between our proposed method and previously established techniques renowned for their disturbance rejection capabilities, namely, the LQG Regulator and MPC. These methodologies embody well-established controller designs. We have devised and implemented noise and disturbance scenarios to assess the performance of these methods. The subsequent figures present a visual depiction of the superior performance of our proposed method compared to both LQG and MPC.
5.3.1 Adaptive pitch attitude hold comparison results
Figure 27a depicts the implementation of theta angle control amidst noise interference. Observable noise is evident in the output of both LQG and MPC. LQG demonstrates superior noise rejection performance compared to MPC. However, the proposed approach consistently yields the most optimal results in terms of noise rejection.
(a) Theta angle control under noise. (b) Error functions of LQG, MPC, and the proposed method under noise.
To enable a more comprehensive comparison among controllers, the clean output is subtracted from the faulty output of each controller, and the resulting error is analyzed. Figure 27b illustrates that MPC exhibits the highest error amplitudes, followed by LQG with lower error amplitudes, while the proposed method demonstrates the lowest error amplitudes. Consequently, in a broader assessment, MPC displays the least favorable performance, whereas our proposed method stands out as the most proficient in noise rejection.
Table 1 presents the RMSE values for the various controllers, serving as a metric to assess the effectiveness of our method in mitigating noise. As depicted in Table 1, the RMSE value for MPC is the highest, followed by a lower RMSE value for LQG. In contrast, the RMSE value for the proposed method is the smallest. This signifies the superior noise rejection capability of our proposed method compared to both LQG and MPC.
RMSE values
| Controller | RMSE value |
|---|---|
| LQG | 0.0568 |
| MPC | 0.3260 |
| Proposed method | 2.0568 ×
|
Figure 28a and b illustrate a discernible trend wherein the level of noise introduced to the system’s output undergoes an increase compared with Figure 27a and b. Notably, the magnitude of noise amplification is considerably higher in the systems controlled by LQG and MPC. Conversely, the increment in noise for the system governed by our proposed method is notably modest. This particular scenario becomes evident when examining the relevant information provided in Figure 28a and b.
(a) Theta angle control under white noise disturbance. (b) Error functions of LQG, MPC, and the proposed method under white noise disturbance.
Table 2 presents a tabulated representation of the RMSE values associated with the different controllers, serving as a quantitative measure to evaluate the efficacy of our method in mitigating noise. As illustrated in Table 2, MPC exhibits the highest RMSE value, while LQG displays a comparatively lower RMSE value. In sharp contrast, the RMSE value associated with our proposed method is the most minimal. This underscores the heightened noise rejection proficiency of our proposed method compared to both LQG and MPC.
RMSE values
| Controller | RMSE value |
|---|---|
| LQG | 0.1796 |
| MPC | 1.6703 |
| Proposed method | 2.0567 ×
|
5.3.2 Adaptive altitude hold comparison results
Figure 29a elucidates the administration of altitude control in the presence of ramp and sinusoidal disturbances. It is apparent that both LQG and MPC exhibit substantial disturbance contributions in their outputs. LQG demonstrates superior disturbance rejection performance compared to MPC. However, the recommended approach consistently produces the most favorable outcomes in terms of disturbance rejection.
(a) Altitude control under ramp and sinusoidal disturbances. (b)Error functions of LQG, MPC, and the proposed method under ramp and sinusoidal disturbances.
To enable a more rigorous comparison among the controllers, the clean output is subtracted from the faulty output of each controller, and the resulting errors are examined. As depicted in Figure 29b, MPC exhibits the largest error amplitudes, LQG displays smaller error amplitudes, and the proposed method exhibits the lowest error amplitudes. Therefore, in a comprehensive assessment, MPC is characterized by the poorest performance, while our proposed method demonstrates the most superior performance in the context of disturbance rejection.
Table 3 provides the RMSE values for the controllers, serving as a metric to convey the superiority of our method in mitigating ramp and sinusoidal disturbances. As evidenced in Table 3, MPC exhibits the highest RMSE value, followed by LQG with a lower RMSE value, while the proposed method boasts the lowest RMSE value. This firmly underscores the superior disturbance rejection capabilities of our proposed method compared to both LQG and MPC.
RMSE values
| Controller | RMSE value |
|---|---|
| LQG | 140.1356 |
| MPC | 69.3386 |
| Proposed method | 2.7697 ×
|
5.3.3 Adaptive yaw autopilot comparison results
Figure 30a illustrates the management of psi angle control under the influence of a step and white noise disturbances. It is evident that both LQG and MPC approaches exhibit a level of noise in their outputs. LQG demonstrates superior performance in rejecting both step disturbance and white noise when compared to MPC. Remarkably, the recommended approach consistently yields the most favorable outcomes concerning noise rejection.
(a) Psi angle control under step and white noise disturbances. (b) Error functions of LQG, MPC, and the proposed method under step white noise and disturbances.
To enable a more rigorous comparison among the controllers, we subtract the clean output from the faulty output of each controller and analyze the resulting error. As illustrated in Figure 30b, MPC displays the largest error amplitudes, while LQG exhibits smaller error amplitudes, and the proposed method showcases the lowest error amplitudes. Therefore, in a comprehensive evaluation, MPC demonstrates the poorest performance, whereas our proposed method emerges as the top performer in terms of noise rejection.
Table 4 illustrates the RMSE values for the controllers, providing evidence of the superior performance of our method in mitigating step disturbance and white noise. As evident in Table 4, the RMSE value for MPC is the highest, while LQG demonstrates a lower RMSE value than MPC. Importantly, the RMSE value for our proposed method is the lowest among the three. This unequivocally demonstrates that our proposed method surpasses both LQG and MPC in terms of white noise rejection.
RMSE values
| Controller | RMSE value |
|---|---|
| LQG | 16.1546 |
| MPC | 123.8637 |
| Proposed method | 2.3107 ×
|
6 Discussion
In this section, we scientifically present our method by framing it within the subsequent paragraph. This approach ensures a structured and coherent explanation of our methodology.
Main findings of the present study: The current study focuses on developing autopilots for stability, control, and the rejection of external disturbances. The proposed method provides significant disturbance rejection properties by rejecting severe disturbances. In the comparison part of the simulation results, the proposed method exhibits superiority over previous methods having disturbance rejection properties. For instance, LQG and MPC fail to mitigate harsh disturbances, and do not provide acceptable responses. Overall, providing novel, advanced, and superior disturbance rejection properties are the main findings for this study.
Comparison with other studies: In comparison to existing studies, the integration of ESC with autopilots presents a novel approach to enhance disturbance rejection in aircraft systems. Unlike traditional autopilots lacking adaptive capabilities, the proposed method provides superior disturbance rejection, surpassing robust controllers such as LQG Regulator and MPC by effectively rejecting severe disturbances.
Implication and explanation of findings: The effectiveness and benefits of the proposed method can be shown by explaining the findings of the proposed work. The proposed method demonstrates excellent performance both in normal conditions and under disturbances. The proposed autopilot is able to reject harsh disturbances. This feature provides superiority for the proposed method in the field of disturbance rejection control because other previous controllers cannot reject these external factors. The explanation of the findings can be made with these expressions. The findings of this study bear significant implications for the field of autonomous flight control in aircraft UAVs. Since the proposed method rejects severe disturbances, it can be implicated that this method provides robustness when severe environmental condition occurs during flight. The Autopilot-ESC integration method yields a novel outcome for aircraft control that provides significant safety for UAV systems during flight. Enhanced performance during specific missions is achievable with reduced reliance on remote control, facilitated by this novel and robust disturbance rejection controller. The proposed method aids in minimizing the risk of accidents or damage to the UAV and its surroundings, ensuring safe and reliable operation in various environments. The proposed approach enables the UAV to adjust its behavior in real-time, and enhance the overall mission success rates, even in challenging situations where disturbances may occur.
Strengths and limitations: One strength of this study lies in its innovative and novel approach to enhance disturbance rejection in aircraft autopilots, which can profoundly impact the safety and reliability of autonomous flight operations under external disturbances. The newly designed proposed autopilots demonstrate robust disturbance rejection properties, effectively rejecting harsh disturbances. In this regard, they outperform previous methods with disturbance rejection capabilities. However, the study primarily focuses on disturbance rejection and may not address all aspects of autopilot performance comprehensively. Another significant drawback of the proposed method is its reliance on a single optimization criterion, typically based on the system’s performance metric. In addition, ESC might suffer from slow convergence rates, potentially impairing its effectiveness in disturbance detection and recovery.
7 Conclusion
This study introduces enhanced autopilots with disturbance rejection capabilities, specifically focusing on pitch attitude hold autopilot, altitude hold autopilot, and yaw autopilot. The augmentation of disturbance rejection features was achieved by integrating the ESC algorithm into these autopilots. This autopilot is adaptable to both stable and unstable systems. The innovative approach involves the construction of two distinct parts, each serving a specific purpose. The inner part utilizes the autopilot for optimal stability and control under normal conditions, while the outer part incorporates ESC for disturbance rejection by mitigating severe external disturbances. ESC ensures that the system maintains the desired control level despite adverse disturbances. The simulation results illustrate that the autopilot is highly effective in achieving optimal flight conditions, while ESC proves essential for mitigating harsh disturbances. The novelty of this approach lies in the elimination of severe disturbances, resulting in a unique disturbance rejection adaptive autopilot through the integration of ESC.
In conclusion, the integration of ESC with conventional autopilots represents a significant advancement in enhancing the disturbance rejection capabilities of aircraft UAV systems. By incorporating ESC into pitch attitude hold autopilot, altitude hold autopilot, and yaw autopilot, these systems acquire adaptive features capable of effectively managing external disturbances. Through simulations, it has been demonstrated that the autopilot-ESC integration surpasses the capabilities of previous methods like LQG and MPC. The theoretical contributions of this study lie in the development of a robust and effective approach by utilizing the ESC algorithm together with conventional autopilots for managing aircraft systems, stability, control, and rejecting external disturbances, ultimately advancing the field of autonomous flight control. However, the novel contribution in this research is to provide advanced disturbance rejection properties to conventional autopilots by integrating ESC to them, thereby transforming them into innovative and superior controllers.
While the study proposes an innovative method of integrating the ESC algorithm with conventional autopilots to enhance disturbance rejection capabilities and adaptability to external disturbances, several limitations should be noted. Although the study emphasizes the superiority of the upgraded autopilots over robust controllers like LQG and MPC in handling various disturbance types, the comparison may not fully capture the performance differences under all possible scenarios. Additionally, the complexity introduced by ESC integration may pose challenges to computational efficiency. Finally, the study primarily focuses on the pitch attitude hold, altitude hold, and yaw autopilots, potentially limiting the generalizability of the findings to other autopilot functionalities or aircraft configurations. Prospects for future research regarding the proposed method include flying a UAV formation with disturbance rejection properties. Moreover, optimization of the trajectory of a UAV group is another prospect for future investigation.
Key results: The proposed approach provides key results as disturbance rejection capabilities, adapting parameters for unknown inputs, and restoring controlled responses. For instance, the proposed method significantly provides strong disturbance handling for autopilots by successfully eliminating various external factors. Moreover, it enhances aircraft operation, reduces operator workload, and ensures reliable autonomous flight capabilities. Furthermore, the adaptability of the Autopilot-ESC to the changing environmental conditions makes it suitable to be employed in aircraft UAVs. Finally, the proposed method shows superiority properties to compare with other robust controllers like LGQ regulator and MPC in severe disturbance elimination.
Significance of key results: The key results highlight the significance of the proposed method in maintaining control and stability under severe disturbances, underscoring its essential role in achieving reliable and safe flight operations. By effectively mitigating disturbances, the autopilot ensures optimal flight conditions even in challenging environments. In addition, enhancing aircraft operation, decreasing operator workload and providing safety are very crucial for the flight field. Moreover, key results highlight superiority of the proposed method that is very significant for minimizing the effects of disturbances on UAVs. Overall, this innovative approach represents a unique solution for enhancing aircraft safety and performance through newly designed disturbance rejection adaptive autopilot systems.
The integration of the ESC algorithm into these autopilots marks a novel approach, enabling adaptability to both stable and unstable systems. We enabled a novel and superior disturbance rejection property for the conventional autopilots in this method. By constructing a dual-part system, where the inner part ensures stability and control while the outer part provides adaptability for disturbance rejection through ESC, the autopilot demonstrates remarkable resilience against adverse external factors. This is a superior contribution in this field. The application of ESC with autopilots in response to external factors showcases its efficacy in maintaining the desired control level and restoring system stability. Ultimately, this research contributes new knowledge by presenting a unique and superior disturbance rejection adaptive autopilot system, eliminating disturbances, and enhancing aircraft safety and performance in challenging operational environments.
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Funding information: Authors state no funding involved.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and consented to its submission to the journal, reviewed all the results and approved the final version of the manuscript. HB managed the research, methodology determination, conceptualization and design of the study, and preparation of the manuscript. IB reviewed and edited the manuscript, managed analysis, interpretation, and provided feedback to reach the publication standards.
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Conflict of interest: Authors state no conflict of interest.
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Data availability statement: The data are not publicly available due to privacy or ethical restrictions.
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- Impact of insulation on energy consumption and CO2 emissions in high-rise commercial buildings at various climate zones
- Advanced autopilot design with extremum-seeking control for aircraft control
- Adaptive multidimensional trust-based recommendation model for peer to peer applications
- Effects of CFRP sheets on the flexural behavior of high-strength concrete beam
- Enhancing urban sustainability through industrial synergy: A multidisciplinary framework for integrating sustainable industrial practices within urban settings – The case of Hamadan industrial city
- Advanced vibrant controller results of an energetic framework structure
- Application of the Taguchi method and RSM for process parameter optimization in AWSJ machining of CFRP composite-based orthopedic implants
- Improved correlation of soil modulus with SPT N values
- Technologies for high-temperature batch annealing of grain-oriented electrical steel: An overview
- Assessing the need for the adoption of digitalization in Indian small and medium enterprises
- A non-ideal hybridization issue for vertical TFET-based dielectric-modulated biosensor
- Optimizing data retrieval for enhanced data integrity verification in cloud environments
- Performance analysis of nonlinear crosstalk of WDM systems using modulation schemes criteria
- Nonlinear finite-element analysis of RC beams with various opening near supports
- Thermal analysis of Fe3O4–Cu/water over a cone: a fractional Maxwell model
- Radial–axial runner blade design using the coordinate slice technique
- Theoretical and experimental comparison between straight and curved continuous box girders
- Effect of the reinforcement ratio on the mechanical behaviour of textile-reinforced concrete composite: Experiment and numerical modeling
- Experimental and numerical investigation on composite beam–column joint connection behavior using different types of connection schemes
- Enhanced performance and robustness in anti-lock brake systems using barrier function-based integral sliding mode control
- Evaluation of the creep strength of samples produced by fused deposition modeling
- A combined feedforward-feedback controller design for nonlinear systems
- Effect of adjacent structures on footing settlement for different multi-building arrangements
- Analyzing the impact of curved tracks on wheel flange thickness reduction in railway systems
- Review Articles
- Mechanical and smart properties of cement nanocomposites containing nanomaterials: A brief review
- Applications of nanotechnology and nanoproduction techniques
- Relationship between indoor environmental quality and guests’ comfort and satisfaction at green hotels: A comprehensive review
- Communication
- Techniques to mitigate the admission of radon inside buildings
- Erratum
- Erratum to “Effect of short heat treatment on mechanical properties and shape memory properties of Cu–Al–Ni shape memory alloy”
- Special Issue: AESMT-3 - Part II
- Integrated fuzzy logic and multicriteria decision model methods for selecting suitable sites for wastewater treatment plant: A case study in the center of Basrah, Iraq
- Physical and mechanical response of porous metals composites with nano-natural additives
- Special Issue: AESMT-4 - Part II
- New recycling method of lubricant oil and the effect on the viscosity and viscous shear as an environmentally friendly
- Identify the effect of Fe2O3 nanoparticles on mechanical and microstructural characteristics of aluminum matrix composite produced by powder metallurgy technique
- Static behavior of piled raft foundation in clay
- Ultra-low-power CMOS ring oscillator with minimum power consumption of 2.9 pW using low-voltage biasing technique
- Using ANN for well type identifying and increasing production from Sa’di formation of Halfaya oil field – Iraq
- Optimizing the performance of concrete tiles using nano-papyrus and carbon fibers
- Special Issue: AESMT-5 - Part II
- Comparative the effect of distribution transformer coil shape on electromagnetic forces and their distribution using the FEM
- The complex of Weyl module in free characteristic in the event of a partition (7,5,3)
- Restrained captive domination number
- Experimental study of improving hot mix asphalt reinforced with carbon fibers
- Asphalt binder modified with recycled tyre rubber
- Thermal performance of radiant floor cooling with phase change material for energy-efficient buildings
- Surveying the prediction of risks in cryptocurrency investments using recurrent neural networks
- A deep reinforcement learning framework to modify LQR for an active vibration control applied to 2D building models
- Evaluation of mechanically stabilized earth retaining walls for different soil–structure interaction methods: A review
- Assessment of heat transfer in a triangular duct with different configurations of ribs using computational fluid dynamics
- Sulfate removal from wastewater by using waste material as an adsorbent
- Experimental investigation on strengthening lap joints subjected to bending in glulam timber beams using CFRP sheets
- A study of the vibrations of a rotor bearing suspended by a hybrid spring system of shape memory alloys
- Stability analysis of Hub dam under rapid drawdown
- Developing ANFIS-FMEA model for assessment and prioritization of potential trouble factors in Iraqi building projects
- Numerical and experimental comparison study of piled raft foundation
- Effect of asphalt modified with waste engine oil on the durability properties of hot asphalt mixtures with reclaimed asphalt pavement
- Hydraulic model for flood inundation in Diyala River Basin using HEC-RAS, PMP, and neural network
- Numerical study on discharge capacity of piano key side weir with various ratios of the crest length to the width
- The optimal allocation of thyristor-controlled series compensators for enhancement HVAC transmission lines Iraqi super grid by using seeker optimization algorithm
- Numerical and experimental study of the impact on aerodynamic characteristics of the NACA0012 airfoil
- Effect of nano-TiO2 on physical and rheological properties of asphalt cement
- Performance evolution of novel palm leaf powder used for enhancing hot mix asphalt
- Performance analysis, evaluation, and improvement of selected unsignalized intersection using SIDRA software – Case study
- Flexural behavior of RC beams externally reinforced with CFRP composites using various strategies
- Influence of fiber types on the properties of the artificial cold-bonded lightweight aggregates
- Experimental investigation of RC beams strengthened with externally bonded BFRP composites
- Generalized RKM methods for solving fifth-order quasi-linear fractional partial differential equation
- An experimental and numerical study investigating sediment transport position in the bed of sewer pipes in Karbala
- Role of individual component failure in the performance of a 1-out-of-3 cold standby system: A Markov model approach
- Implementation for the cases (5, 4) and (5, 4)/(2, 0)
- Center group actions and related concepts
- Experimental investigation of the effect of horizontal construction joints on the behavior of deep beams
- Deletion of a vertex in even sum domination
- Deep learning techniques in concrete powder mix designing
- Effect of loading type in concrete deep beam with strut reinforcement
- Studying the effect of using CFRP warping on strength of husk rice concrete columns
- Parametric analysis of the influence of climatic factors on the formation of traditional buildings in the city of Al Najaf
- Suitability location for landfill using a fuzzy-GIS model: A case study in Hillah, Iraq
- Hybrid approach for cost estimation of sustainable building projects using artificial neural networks
- Assessment of indirect tensile stress and tensile–strength ratio and creep compliance in HMA mixes with micro-silica and PMB
- Density functional theory to study stopping power of proton in water, lung, bladder, and intestine
- A review of single flow, flow boiling, and coating microchannel studies
- Effect of GFRP bar length on the flexural behavior of hybrid concrete beams strengthened with NSM bars
- Exploring the impact of parameters on flow boiling heat transfer in microchannels and coated microtubes: A comprehensive review
- Crumb rubber modification for enhanced rutting resistance in asphalt mixtures
- Special Issue: AESMT-6
- Design of a new sorting colors system based on PLC, TIA portal, and factory I/O programs
- Forecasting empirical formula for suspended sediment load prediction at upstream of Al-Kufa barrage, Kufa City, Iraq
- Optimization and characterization of sustainable geopolymer mortars based on palygorskite clay, water glass, and sodium hydroxide
- Sediment transport modelling upstream of Al Kufa Barrage
- Study of energy loss, range, and stopping time for proton in germanium and copper materials
- Effect of internal and external recycle ratios on the nutrient removal efficiency of anaerobic/anoxic/oxic (VIP) wastewater treatment plant
- Enhancing structural behaviour of polypropylene fibre concrete columns longitudinally reinforced with fibreglass bars
- Sustainable road paving: Enhancing concrete paver blocks with zeolite-enhanced cement
- Evaluation of the operational performance of Karbala waste water treatment plant under variable flow using GPS-X model
- Design and simulation of photonic crystal fiber for highly sensitive chemical sensing applications
- Optimization and design of a new column sequencing for crude oil distillation at Basrah refinery
- Inductive 3D numerical modelling of the tibia bone using MRI to examine von Mises stress and overall deformation
- An image encryption method based on modified elliptic curve Diffie-Hellman key exchange protocol and Hill Cipher
- Experimental investigation of generating superheated steam using a parabolic dish with a cylindrical cavity receiver: A case study
- Effect of surface roughness on the interface behavior of clayey soils
- Investigated of the optical properties for SiO2 by using Lorentz model
- Measurements of induced vibrations due to steel pipe pile driving in Al-Fao soil: Effect of partial end closure
- Experimental and numerical studies of ballistic resistance of hybrid sandwich composite body armor
- Evaluation of clay layer presence on shallow foundation settlement in dry sand under an earthquake
- Optimal design of mechanical performances of asphalt mixtures comprising nano-clay additives
- Advancing seismic performance: Isolators, TMDs, and multi-level strategies in reinforced concrete buildings
- Predicted evaporation in Basrah using artificial neural networks
- Energy management system for a small town to enhance quality of life
- Numerical study on entropy minimization in pipes with helical airfoil and CuO nanoparticle integration
- Equations and methodologies of inlet drainage system discharge coefficients: A review
- Thermal buckling analysis for hybrid and composite laminated plate by using new displacement function
- Investigation into the mechanical and thermal properties of lightweight mortar using commercial beads or recycled expanded polystyrene
- Experimental and theoretical analysis of single-jet column and concrete column using double-jet grouting technique applied at Al-Rashdia site
- The impact of incorporating waste materials on the mechanical and physical characteristics of tile adhesive materials
- Seismic resilience: Innovations in structural engineering for earthquake-prone areas
- Automatic human identification using fingerprint images based on Gabor filter and SIFT features fusion
- Performance of GRKM-method for solving classes of ordinary and partial differential equations of sixth-orders
- Visible light-boosted photodegradation activity of Ag–AgVO3/Zn0.5Mn0.5Fe2O4 supported heterojunctions for effective degradation of organic contaminates
- Production of sustainable concrete with treated cement kiln dust and iron slag waste aggregate
- Key effects on the structural behavior of fiber-reinforced lightweight concrete-ribbed slabs: A review
- A comparative analysis of the energy dissipation efficiency of various piano key weir types
- Special Issue: Transport 2022 - Part II
- Variability in road surface temperature in urban road network – A case study making use of mobile measurements
- Special Issue: BCEE5-2023
- Evaluation of reclaimed asphalt mixtures rejuvenated with waste engine oil to resist rutting deformation
- Assessment of potential resistance to moisture damage and fatigue cracks of asphalt mixture modified with ground granulated blast furnace slag
- Investigating seismic response in adjacent structures: A study on the impact of buildings’ orientation and distance considering soil–structure interaction
- Improvement of porosity of mortar using polyethylene glycol pre-polymer-impregnated mortar
- Three-dimensional analysis of steel beam-column bolted connections
- Assessment of agricultural drought in Iraq employing Landsat and MODIS imagery
- Performance evaluation of grouted porous asphalt concrete
- Optimization of local modified metakaolin-based geopolymer concrete by Taguchi method
- Effect of waste tire products on some characteristics of roller-compacted concrete
- Studying the lateral displacement of retaining wall supporting sandy soil under dynamic loads
- Seismic performance evaluation of concrete buttress dram (Dynamic linear analysis)
- Behavior of soil reinforced with micropiles
- Possibility of production high strength lightweight concrete containing organic waste aggregate and recycled steel fibers
- An investigation of self-sensing and mechanical properties of smart engineered cementitious composites reinforced with functional materials
- Forecasting changes in precipitation and temperatures of a regional watershed in Northern Iraq using LARS-WG model
- Experimental investigation of dynamic soil properties for modeling energy-absorbing layers
- Numerical investigation of the effect of longitudinal steel reinforcement ratio on the ductility of concrete beams
- An experimental study on the tensile properties of reinforced asphalt pavement
- Self-sensing behavior of hot asphalt mixture with steel fiber-based additive
- Behavior of ultra-high-performance concrete deep beams reinforced by basalt fibers
- Optimizing asphalt binder performance with various PET types
- Investigation of the hydraulic characteristics and homogeneity of the microstructure of the air voids in the sustainable rigid pavement
- Enhanced biogas production from municipal solid waste via digestion with cow manure: A case study
- Special Issue: AESMT-7 - Part I
- Preparation and investigation of cobalt nanoparticles by laser ablation: Structure, linear, and nonlinear optical properties
- Seismic analysis of RC building with plan irregularity in Baghdad/Iraq to obtain the optimal behavior
- The effect of urban environment on large-scale path loss model’s main parameters for mmWave 5G mobile network in Iraq
- Formatting a questionnaire for the quality control of river bank roads
- Vibration suppression of smart composite beam using model predictive controller
- Machine learning-based compressive strength estimation in nanomaterial-modified lightweight concrete
- In-depth analysis of critical factors affecting Iraqi construction projects performance
- Behavior of container berth structure under the influence of environmental and operational loads
- Energy absorption and impact response of ballistic resistance laminate
- Effect of water-absorbent polymer balls in internal curing on punching shear behavior of bubble slabs
- Effect of surface roughness on interface shear strength parameters of sandy soils
- Evaluating the interaction for embedded H-steel section in normal concrete under monotonic and repeated loads
- Estimation of the settlement of pile head using ANN and multivariate linear regression based on the results of load transfer method
- Enhancing communication: Deep learning for Arabic sign language translation
- A review of recent studies of both heat pipe and evaporative cooling in passive heat recovery
- Effect of nano-silica on the mechanical properties of LWC
- An experimental study of some mechanical properties and absorption for polymer-modified cement mortar modified with superplasticizer
- Digital beamforming enhancement with LSTM-based deep learning for millimeter wave transmission
- Developing an efficient planning process for heritage buildings maintenance in Iraq
- Design and optimization of two-stage controller for three-phase multi-converter/multi-machine electric vehicle
- Evaluation of microstructure and mechanical properties of Al1050/Al2O3/Gr composite processed by forming operation ECAP
- Calculations of mass stopping power and range of protons in organic compounds (CH3OH, CH2O, and CO2) at energy range of 0.01–1,000 MeV
- Investigation of in vitro behavior of composite coating hydroxyapatite-nano silver on 316L stainless steel substrate by electrophoretic technic for biomedical tools
- A review: Enhancing tribological properties of journal bearings composite materials
- Improvements in the randomness and security of digital currency using the photon sponge hash function through Maiorana–McFarland S-box replacement
- Design a new scheme for image security using a deep learning technique of hierarchical parameters
- Special Issue: ICES 2023
- Comparative geotechnical analysis for ultimate bearing capacity of precast concrete piles using cone resistance measurements
- Visualizing sustainable rainwater harvesting: A case study of Karbala Province
- Geogrid reinforcement for improving bearing capacity and stability of square foundations
- Evaluation of the effluent concentrations of Karbala wastewater treatment plant using reliability analysis
- Adsorbent made with inexpensive, local resources
- Effect of drain pipes on seepage and slope stability through a zoned earth dam
- Sediment accumulation in an 8 inch sewer pipe for a sample of various particles obtained from the streets of Karbala city, Iraq
- Special Issue: IETAS 2024 - Part I
- Analyzing the impact of transfer learning on explanation accuracy in deep learning-based ECG recognition systems
- Effect of scale factor on the dynamic response of frame foundations
- Improving multi-object detection and tracking with deep learning, DeepSORT, and frame cancellation techniques
- The impact of using prestressed CFRP bars on the development of flexural strength
- Assessment of surface hardness and impact strength of denture base resins reinforced with silver–titanium dioxide and silver–zirconium dioxide nanoparticles: In vitro study
- A data augmentation approach to enhance breast cancer detection using generative adversarial and artificial neural networks
- Modification of the 5D Lorenz chaotic map with fuzzy numbers for video encryption in cloud computing
- Special Issue: 51st KKBN - Part I
- Evaluation of static bending caused damage of glass-fiber composite structure using terahertz inspection
Artikel in diesem Heft
- Regular Articles
- Methodology of automated quality management
- Influence of vibratory conveyor design parameters on the trough motion and the self-synchronization of inertial vibrators
- Application of finite element method in industrial design, example of an electric motorcycle design project
- Correlative evaluation of the corrosion resilience and passivation properties of zinc and aluminum alloys in neutral chloride and acid-chloride solutions
- Will COVID “encourage” B2B and data exchange engineering in logistic firms?
- Influence of unsupported sleepers on flange climb derailment of two freight wagons
- A hybrid detection algorithm for 5G OTFS waveform for 64 and 256 QAM with Rayleigh and Rician channels
- Effect of short heat treatment on mechanical properties and shape memory properties of Cu–Al–Ni shape memory alloy
- Exploring the potential of ammonia and hydrogen as alternative fuels for transportation
- Impact of insulation on energy consumption and CO2 emissions in high-rise commercial buildings at various climate zones
- Advanced autopilot design with extremum-seeking control for aircraft control
- Adaptive multidimensional trust-based recommendation model for peer to peer applications
- Effects of CFRP sheets on the flexural behavior of high-strength concrete beam
- Enhancing urban sustainability through industrial synergy: A multidisciplinary framework for integrating sustainable industrial practices within urban settings – The case of Hamadan industrial city
- Advanced vibrant controller results of an energetic framework structure
- Application of the Taguchi method and RSM for process parameter optimization in AWSJ machining of CFRP composite-based orthopedic implants
- Improved correlation of soil modulus with SPT N values
- Technologies for high-temperature batch annealing of grain-oriented electrical steel: An overview
- Assessing the need for the adoption of digitalization in Indian small and medium enterprises
- A non-ideal hybridization issue for vertical TFET-based dielectric-modulated biosensor
- Optimizing data retrieval for enhanced data integrity verification in cloud environments
- Performance analysis of nonlinear crosstalk of WDM systems using modulation schemes criteria
- Nonlinear finite-element analysis of RC beams with various opening near supports
- Thermal analysis of Fe3O4–Cu/water over a cone: a fractional Maxwell model
- Radial–axial runner blade design using the coordinate slice technique
- Theoretical and experimental comparison between straight and curved continuous box girders
- Effect of the reinforcement ratio on the mechanical behaviour of textile-reinforced concrete composite: Experiment and numerical modeling
- Experimental and numerical investigation on composite beam–column joint connection behavior using different types of connection schemes
- Enhanced performance and robustness in anti-lock brake systems using barrier function-based integral sliding mode control
- Evaluation of the creep strength of samples produced by fused deposition modeling
- A combined feedforward-feedback controller design for nonlinear systems
- Effect of adjacent structures on footing settlement for different multi-building arrangements
- Analyzing the impact of curved tracks on wheel flange thickness reduction in railway systems
- Review Articles
- Mechanical and smart properties of cement nanocomposites containing nanomaterials: A brief review
- Applications of nanotechnology and nanoproduction techniques
- Relationship between indoor environmental quality and guests’ comfort and satisfaction at green hotels: A comprehensive review
- Communication
- Techniques to mitigate the admission of radon inside buildings
- Erratum
- Erratum to “Effect of short heat treatment on mechanical properties and shape memory properties of Cu–Al–Ni shape memory alloy”
- Special Issue: AESMT-3 - Part II
- Integrated fuzzy logic and multicriteria decision model methods for selecting suitable sites for wastewater treatment plant: A case study in the center of Basrah, Iraq
- Physical and mechanical response of porous metals composites with nano-natural additives
- Special Issue: AESMT-4 - Part II
- New recycling method of lubricant oil and the effect on the viscosity and viscous shear as an environmentally friendly
- Identify the effect of Fe2O3 nanoparticles on mechanical and microstructural characteristics of aluminum matrix composite produced by powder metallurgy technique
- Static behavior of piled raft foundation in clay
- Ultra-low-power CMOS ring oscillator with minimum power consumption of 2.9 pW using low-voltage biasing technique
- Using ANN for well type identifying and increasing production from Sa’di formation of Halfaya oil field – Iraq
- Optimizing the performance of concrete tiles using nano-papyrus and carbon fibers
- Special Issue: AESMT-5 - Part II
- Comparative the effect of distribution transformer coil shape on electromagnetic forces and their distribution using the FEM
- The complex of Weyl module in free characteristic in the event of a partition (7,5,3)
- Restrained captive domination number
- Experimental study of improving hot mix asphalt reinforced with carbon fibers
- Asphalt binder modified with recycled tyre rubber
- Thermal performance of radiant floor cooling with phase change material for energy-efficient buildings
- Surveying the prediction of risks in cryptocurrency investments using recurrent neural networks
- A deep reinforcement learning framework to modify LQR for an active vibration control applied to 2D building models
- Evaluation of mechanically stabilized earth retaining walls for different soil–structure interaction methods: A review
- Assessment of heat transfer in a triangular duct with different configurations of ribs using computational fluid dynamics
- Sulfate removal from wastewater by using waste material as an adsorbent
- Experimental investigation on strengthening lap joints subjected to bending in glulam timber beams using CFRP sheets
- A study of the vibrations of a rotor bearing suspended by a hybrid spring system of shape memory alloys
- Stability analysis of Hub dam under rapid drawdown
- Developing ANFIS-FMEA model for assessment and prioritization of potential trouble factors in Iraqi building projects
- Numerical and experimental comparison study of piled raft foundation
- Effect of asphalt modified with waste engine oil on the durability properties of hot asphalt mixtures with reclaimed asphalt pavement
- Hydraulic model for flood inundation in Diyala River Basin using HEC-RAS, PMP, and neural network
- Numerical study on discharge capacity of piano key side weir with various ratios of the crest length to the width
- The optimal allocation of thyristor-controlled series compensators for enhancement HVAC transmission lines Iraqi super grid by using seeker optimization algorithm
- Numerical and experimental study of the impact on aerodynamic characteristics of the NACA0012 airfoil
- Effect of nano-TiO2 on physical and rheological properties of asphalt cement
- Performance evolution of novel palm leaf powder used for enhancing hot mix asphalt
- Performance analysis, evaluation, and improvement of selected unsignalized intersection using SIDRA software – Case study
- Flexural behavior of RC beams externally reinforced with CFRP composites using various strategies
- Influence of fiber types on the properties of the artificial cold-bonded lightweight aggregates
- Experimental investigation of RC beams strengthened with externally bonded BFRP composites
- Generalized RKM methods for solving fifth-order quasi-linear fractional partial differential equation
- An experimental and numerical study investigating sediment transport position in the bed of sewer pipes in Karbala
- Role of individual component failure in the performance of a 1-out-of-3 cold standby system: A Markov model approach
- Implementation for the cases (5, 4) and (5, 4)/(2, 0)
- Center group actions and related concepts
- Experimental investigation of the effect of horizontal construction joints on the behavior of deep beams
- Deletion of a vertex in even sum domination
- Deep learning techniques in concrete powder mix designing
- Effect of loading type in concrete deep beam with strut reinforcement
- Studying the effect of using CFRP warping on strength of husk rice concrete columns
- Parametric analysis of the influence of climatic factors on the formation of traditional buildings in the city of Al Najaf
- Suitability location for landfill using a fuzzy-GIS model: A case study in Hillah, Iraq
- Hybrid approach for cost estimation of sustainable building projects using artificial neural networks
- Assessment of indirect tensile stress and tensile–strength ratio and creep compliance in HMA mixes with micro-silica and PMB
- Density functional theory to study stopping power of proton in water, lung, bladder, and intestine
- A review of single flow, flow boiling, and coating microchannel studies
- Effect of GFRP bar length on the flexural behavior of hybrid concrete beams strengthened with NSM bars
- Exploring the impact of parameters on flow boiling heat transfer in microchannels and coated microtubes: A comprehensive review
- Crumb rubber modification for enhanced rutting resistance in asphalt mixtures
- Special Issue: AESMT-6
- Design of a new sorting colors system based on PLC, TIA portal, and factory I/O programs
- Forecasting empirical formula for suspended sediment load prediction at upstream of Al-Kufa barrage, Kufa City, Iraq
- Optimization and characterization of sustainable geopolymer mortars based on palygorskite clay, water glass, and sodium hydroxide
- Sediment transport modelling upstream of Al Kufa Barrage
- Study of energy loss, range, and stopping time for proton in germanium and copper materials
- Effect of internal and external recycle ratios on the nutrient removal efficiency of anaerobic/anoxic/oxic (VIP) wastewater treatment plant
- Enhancing structural behaviour of polypropylene fibre concrete columns longitudinally reinforced with fibreglass bars
- Sustainable road paving: Enhancing concrete paver blocks with zeolite-enhanced cement
- Evaluation of the operational performance of Karbala waste water treatment plant under variable flow using GPS-X model
- Design and simulation of photonic crystal fiber for highly sensitive chemical sensing applications
- Optimization and design of a new column sequencing for crude oil distillation at Basrah refinery
- Inductive 3D numerical modelling of the tibia bone using MRI to examine von Mises stress and overall deformation
- An image encryption method based on modified elliptic curve Diffie-Hellman key exchange protocol and Hill Cipher
- Experimental investigation of generating superheated steam using a parabolic dish with a cylindrical cavity receiver: A case study
- Effect of surface roughness on the interface behavior of clayey soils
- Investigated of the optical properties for SiO2 by using Lorentz model
- Measurements of induced vibrations due to steel pipe pile driving in Al-Fao soil: Effect of partial end closure
- Experimental and numerical studies of ballistic resistance of hybrid sandwich composite body armor
- Evaluation of clay layer presence on shallow foundation settlement in dry sand under an earthquake
- Optimal design of mechanical performances of asphalt mixtures comprising nano-clay additives
- Advancing seismic performance: Isolators, TMDs, and multi-level strategies in reinforced concrete buildings
- Predicted evaporation in Basrah using artificial neural networks
- Energy management system for a small town to enhance quality of life
- Numerical study on entropy minimization in pipes with helical airfoil and CuO nanoparticle integration
- Equations and methodologies of inlet drainage system discharge coefficients: A review
- Thermal buckling analysis for hybrid and composite laminated plate by using new displacement function
- Investigation into the mechanical and thermal properties of lightweight mortar using commercial beads or recycled expanded polystyrene
- Experimental and theoretical analysis of single-jet column and concrete column using double-jet grouting technique applied at Al-Rashdia site
- The impact of incorporating waste materials on the mechanical and physical characteristics of tile adhesive materials
- Seismic resilience: Innovations in structural engineering for earthquake-prone areas
- Automatic human identification using fingerprint images based on Gabor filter and SIFT features fusion
- Performance of GRKM-method for solving classes of ordinary and partial differential equations of sixth-orders
- Visible light-boosted photodegradation activity of Ag–AgVO3/Zn0.5Mn0.5Fe2O4 supported heterojunctions for effective degradation of organic contaminates
- Production of sustainable concrete with treated cement kiln dust and iron slag waste aggregate
- Key effects on the structural behavior of fiber-reinforced lightweight concrete-ribbed slabs: A review
- A comparative analysis of the energy dissipation efficiency of various piano key weir types
- Special Issue: Transport 2022 - Part II
- Variability in road surface temperature in urban road network – A case study making use of mobile measurements
- Special Issue: BCEE5-2023
- Evaluation of reclaimed asphalt mixtures rejuvenated with waste engine oil to resist rutting deformation
- Assessment of potential resistance to moisture damage and fatigue cracks of asphalt mixture modified with ground granulated blast furnace slag
- Investigating seismic response in adjacent structures: A study on the impact of buildings’ orientation and distance considering soil–structure interaction
- Improvement of porosity of mortar using polyethylene glycol pre-polymer-impregnated mortar
- Three-dimensional analysis of steel beam-column bolted connections
- Assessment of agricultural drought in Iraq employing Landsat and MODIS imagery
- Performance evaluation of grouted porous asphalt concrete
- Optimization of local modified metakaolin-based geopolymer concrete by Taguchi method
- Effect of waste tire products on some characteristics of roller-compacted concrete
- Studying the lateral displacement of retaining wall supporting sandy soil under dynamic loads
- Seismic performance evaluation of concrete buttress dram (Dynamic linear analysis)
- Behavior of soil reinforced with micropiles
- Possibility of production high strength lightweight concrete containing organic waste aggregate and recycled steel fibers
- An investigation of self-sensing and mechanical properties of smart engineered cementitious composites reinforced with functional materials
- Forecasting changes in precipitation and temperatures of a regional watershed in Northern Iraq using LARS-WG model
- Experimental investigation of dynamic soil properties for modeling energy-absorbing layers
- Numerical investigation of the effect of longitudinal steel reinforcement ratio on the ductility of concrete beams
- An experimental study on the tensile properties of reinforced asphalt pavement
- Self-sensing behavior of hot asphalt mixture with steel fiber-based additive
- Behavior of ultra-high-performance concrete deep beams reinforced by basalt fibers
- Optimizing asphalt binder performance with various PET types
- Investigation of the hydraulic characteristics and homogeneity of the microstructure of the air voids in the sustainable rigid pavement
- Enhanced biogas production from municipal solid waste via digestion with cow manure: A case study
- Special Issue: AESMT-7 - Part I
- Preparation and investigation of cobalt nanoparticles by laser ablation: Structure, linear, and nonlinear optical properties
- Seismic analysis of RC building with plan irregularity in Baghdad/Iraq to obtain the optimal behavior
- The effect of urban environment on large-scale path loss model’s main parameters for mmWave 5G mobile network in Iraq
- Formatting a questionnaire for the quality control of river bank roads
- Vibration suppression of smart composite beam using model predictive controller
- Machine learning-based compressive strength estimation in nanomaterial-modified lightweight concrete
- In-depth analysis of critical factors affecting Iraqi construction projects performance
- Behavior of container berth structure under the influence of environmental and operational loads
- Energy absorption and impact response of ballistic resistance laminate
- Effect of water-absorbent polymer balls in internal curing on punching shear behavior of bubble slabs
- Effect of surface roughness on interface shear strength parameters of sandy soils
- Evaluating the interaction for embedded H-steel section in normal concrete under monotonic and repeated loads
- Estimation of the settlement of pile head using ANN and multivariate linear regression based on the results of load transfer method
- Enhancing communication: Deep learning for Arabic sign language translation
- A review of recent studies of both heat pipe and evaporative cooling in passive heat recovery
- Effect of nano-silica on the mechanical properties of LWC
- An experimental study of some mechanical properties and absorption for polymer-modified cement mortar modified with superplasticizer
- Digital beamforming enhancement with LSTM-based deep learning for millimeter wave transmission
- Developing an efficient planning process for heritage buildings maintenance in Iraq
- Design and optimization of two-stage controller for three-phase multi-converter/multi-machine electric vehicle
- Evaluation of microstructure and mechanical properties of Al1050/Al2O3/Gr composite processed by forming operation ECAP
- Calculations of mass stopping power and range of protons in organic compounds (CH3OH, CH2O, and CO2) at energy range of 0.01–1,000 MeV
- Investigation of in vitro behavior of composite coating hydroxyapatite-nano silver on 316L stainless steel substrate by electrophoretic technic for biomedical tools
- A review: Enhancing tribological properties of journal bearings composite materials
- Improvements in the randomness and security of digital currency using the photon sponge hash function through Maiorana–McFarland S-box replacement
- Design a new scheme for image security using a deep learning technique of hierarchical parameters
- Special Issue: ICES 2023
- Comparative geotechnical analysis for ultimate bearing capacity of precast concrete piles using cone resistance measurements
- Visualizing sustainable rainwater harvesting: A case study of Karbala Province
- Geogrid reinforcement for improving bearing capacity and stability of square foundations
- Evaluation of the effluent concentrations of Karbala wastewater treatment plant using reliability analysis
- Adsorbent made with inexpensive, local resources
- Effect of drain pipes on seepage and slope stability through a zoned earth dam
- Sediment accumulation in an 8 inch sewer pipe for a sample of various particles obtained from the streets of Karbala city, Iraq
- Special Issue: IETAS 2024 - Part I
- Analyzing the impact of transfer learning on explanation accuracy in deep learning-based ECG recognition systems
- Effect of scale factor on the dynamic response of frame foundations
- Improving multi-object detection and tracking with deep learning, DeepSORT, and frame cancellation techniques
- The impact of using prestressed CFRP bars on the development of flexural strength
- Assessment of surface hardness and impact strength of denture base resins reinforced with silver–titanium dioxide and silver–zirconium dioxide nanoparticles: In vitro study
- A data augmentation approach to enhance breast cancer detection using generative adversarial and artificial neural networks
- Modification of the 5D Lorenz chaotic map with fuzzy numbers for video encryption in cloud computing
- Special Issue: 51st KKBN - Part I
- Evaluation of static bending caused damage of glass-fiber composite structure using terahertz inspection
