Band 6, Heft 2 - TAR Conference 2020: Technically Assisted Rehabilitation, October 28 to 29, 2020

The article describes the designers’ perspectives for development and implementation of industrial exoskeletons. Findings are based on the research and own development of commercial available exoskeletons. The authors describe and emphasize the importance of a user centered design and implementation process.

The performance of conventional prosthetic feet depends on material and construction principles. Certain powered feet can even generate net positive mechanical work in order to provide an active push-off. The aim of this study was to evaluate the influence of ankle power on the gait of transfemoral amputees. For this purpose level walking of six transfemoral amputees was analysed with a basic and an active foot and three different power settings of the latter. The results show clear advantages of the active foot in comparison with a basic foot. However, a strong relation of the sound side knee loading parameters with the varied ankle power outputs of the active foot couldn’t be shown.

Stroke survivors often have difficulty performing activities of daily living (ADLs) due to hand impairments. Several assistive devices have been developed for stroke survivors to assist them with ADLs but most of these devices are difficult to don and doff for a stroke survivor due to highly flexed postures of the wrist and digits. This paper presents a hybrid 3D printed mechanical structure for an assistive hand exoskeleton created for stroke survivors. The design facilitates donning and doffing of the assistive exoskeleton by enabling an approach entirely from the dorsal side of the hand, thereby allowing the fingers to stay flexed. The design criteria, resulting design and the prototype development are presented. The initial prototype of the structure, using a hybrid combination of rigid and flexible materials, was lightweight (only 185 g), while maintaining a high range of motion. Future directions for further improvements and user studies are described.

The “BrailleRing” is a refreshable Braille display that allows blind people to read tactile characters on the inside of a rotating ring. Dots are not displayed by moving pins, but by fixed patterns on rotating cuboids. The concept allows for a flexible line-length as well as for a more robust and easy-to-clean device, because it needs far fewer actuators than piezo-electric Braille displays, and these actuators are mechanically isolated from the Braille cells.

Tinnitus is a phantom percept of noise heard only by the affected person. The principal problem of persons suffering from tinnitus is the inability to deflect their attention from the phantom sound, resulting in insomnia and problems with concentration, followed by significant health issues. To date, no therapy would relieve patients from the phantom sound. Instead, commonly used therapeutic approaches for tinnitus aim primarily at the reduction of tinnitus-induced distress and are based on various tinnitus habituation methods. Our project aims to quench the tinnitus percept using an implant. To develop such an implant, this research group joined the INTAKT network initiated by the German Federal Ministry of Education and Research and dedicated to the development of smart implants. During this still ongoing, prospective clinical study, the efficacy of two protocols using electrical stimulation is assessed for tinnitus silencing. The electrical stimulation used in the presented study is non-invasive and applied on three consecutive days in the form of short sessions. In a sample of 48 subjects, following three stimulation sessions, 48% of patients reported a significant reduction of tinnitus loudness; 10% reported a brief increase of tinnitus loudness, and 42% stated no change. In one case, the first course of stimulation led to the total distinguishing of tinnitus. On average, the stimulation did not affect the grade of tinnitus-induced distress during the time of measurement. Our current results prompt us to broaden our investigations, expand the subject sample, and further optimize the stimulation conditions.

Small sensor devices like inertial measurement units enable mobile movement and gait analysis, whereby existing systems differ in data acquisition, data processing, and gait parameter calculation. Concerning the validation, recent studies focus on the captured motion and the influence of sensor positioning with respect to the accuracy of the computed biomechanical parameters in comparison to a reference system. Although soft tissue artifact is a major source of error for skin-mounted sensors, there are no investigations regarding the relative movement between the body segment and sensor attachment itself. The aim of this study is to find an evaluation method and to determine parameters that allow the validation of various sensor attachment types and different sensor positionings. The analysis includes the comparison between an adhesive and strap attachment variant as well as the frontal and lateral sensor placement. To validate different attachments, an optical marker-based tracking system was used to measure the body segment and sensor position during movement. The distance between these two positions was calculated and analyzed to determine suitable validation parameters. Despite the exploratory research, the results suggest a feasible validation method to detect differences between the attachments, independent of the sensor type. To have representative and statistically validated results, further studies that involve more participants are necessary.

We present the first results of work towards a foil-based epiretinal prosthesis that can stimulate retinal cells. The prosthesis receives trigger signals and energy in the form of high intensity infrared radiation. Array-like silicon photodiodes with attached thin film electrodes convert the received infrared light into electrical stimulation signals, which are intended to stimulate ganglion cells. The photodiodes are arranged like stones in a mosaic on an only 10 µm thin and thus flexible polymer foil. Like this, the prosthesis can adapt to the curved shape of the eye and will have close contact with the retina. The photodiode array is fabricated on silicon wafers. Etched trenches guarantee the electrical separation between the individual photodiodes and pixels. Spectral sensitivities of backside-illuminated photodiodes were measured for wafers thinned to different thicknesses. The thin polymer foil is realized by spin coating polyimide on the photodiode array followed by imidization. Via holes are etched into the polyimide film for contacting the pads of the photodiodes. First spin coating tests were performed using silicon wafers without photodiodes but with metal pads and with etched trenches to simulate the gap between individual photodiodes. Although the thickness of the spin-coated polyimide layer was very inhomogeneous, we succeeded in realizing vias for connecting contact pads by thin film gold tracks crossing deep trenches. The realized via holes had inclined sidewalls as desired. Electrical measurements showed sufficient electrical contact between two connected pads.

Children with unilateral cerebral palsy (CCP) benefit from intensive training with the affected side. The SHArKi project strives for a motivational support system, using wristbands with inertial measurements units (IMU) to measure arm function, providing biofeedback as well as motivating stimuli. To consider finger and wrist movements as well, this paper covers concepts for a tangible solution and its first implementation including the gamification development. Finalizations of the demonstrator, an overall functional test as well as concluding feedback from CCP are pending.

In motion analysis marker sets or protocols are mostly developed for gait analysis and it has been shown that the marker set used affects the results of gait analysis. These marker sets are also used for the analysis of high dynamic sports movements. Single-leg landings are a common tool to investigate functional knee stability and further to predict injury risks where frontal plane motion and loading seem to play an important role. Until now, it is unknown how the marker sets affect the motion analysis results of such high dynamic movements. Therefore, the aim of the study was to compare six different marker sets. Three-dimensional motion and force data of single-leg landings in 12 healthy subjects were collected. Six different marker sets consisting of up to 26 markers and two clusters were simultaneously attached to the subjects’ lower limb and pelvis. The results show that particularly, the knee joint angles in the frontal and transverse plane showed the greatest differences between marker sets with in part contrary joint angle directions and great differences in angle magnitude. In addition, the amount of joint load was dependent on the marker set used for analysis. These results show that one must be careful when interpreting and comparing data of the frontal or transverse plane during high dynamic movements.

In view of therapeutic applications, climbing motion analysis has gained increased importance to avoid movements that are prone to cause injuries and to motivate the climber by means of gamification. To date, there remains need to investigate analysis methods for feedback generation that do not require body contact and that can be easily integrated in the climbing setup. Therefore, this study proposes an camera-based approach for contact-less motion analysis that localises the climber’s centre of mass (COM) and derives relevant parameters, such as fluency, force and distance to the wall, from the temporal COM analysis.

This paper reports on the evaluation of recurrent and convolutional neural networks as real-time grasp phase classifiers for future control of neuroprostheses for people with high spinal cord injury. A field-programmable gate array has been chosen as an implementation platform due to its form factor and ability to perform parallel computations, which are specific for the selected neural networks. Three different phases of two grasp patterns and the additional open hand pattern were predicted by means of surface Electromyography (EMG) signals (i.e. Seven classes in total). Across seven healthy subjects, CNN (Convolutional Neural Networks) and RNN (Recurrent Neural Networks) had a mean accuracy of 85.23% with a standard deviation of 4.77% and 112 µs per prediction and 83.30% with a standard deviation of 4.36% and 40 µs per prediction, respectively.

Objectives This pilot field study aimed to detect long-term changes in technology acceptance (TAM), user experience (UX) during use of an experimental demonstrator Bi-Manu-Interact (BMI) in stroke rehabilitation. Methods In 10 therapy sessions, patients performed a 20 min workout per session with the BMI. Patients with stroke were interviewed after the first (T0) and the 10th training session (T1) with a structured questionnaire about UX, TAM and potential to use the BMI at home. Nine patients (n=4 females) aged 33–78 years ( M =60.22; SD =13.17) participated in the study. Results After using the BMI no statistically significant differences have been found in UX and TAM (T0 vs. T1). But small to large effect sizes have been found which imply a practical relevance of the differences. The potential to use the BMI at home showed an increase in readiness for at T1 compared to T0. Conclusion Descriptive data suggest that familiarity gained through repetitive training sessions. The findings are coherent with previous studies.

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases in the world which mainly affects the human’s motor systems. An estimated number of 7–10 million people worldwide suffer from PD. In Germany, the number of people affected by PD lies at about 300,000 and the number rises every year by approximately 13,000. One of the cardinal symptoms of PD is the freezing of gait (FoG), which arises/appears in the late stages of the PD. FoG is defined as an episodic process with increased restriction of movement or complete blockage despite the intention of moving and, as it can lead to falls and injuries and reduces the quality of life, is considered as one of the most disabling symptoms of PD. In this contribution, we introduce a wearable wireless system designed for gait monitoring and non-invasive electrical stimulation (cueing) in case of a FoG episode.