The aim of the project area A.1 is to develop an optimization platform that enables designers of assistive systems to identify the optimal design for the drive system of an assistive wearable device, considering both subjective and objective criteria. The overview of the optimization platform has been determined, its different components have been identified, and the requirements of each section have been decided.

A proof-of-concept study was conducted with the aim of interpreting the user preference in the face of various states of an assistive wearable device using brain signals. In this study, participants were asked to perform a swinging movement of their knee joint while sitting on a chair in front of a screen and wearing a 1 DOF knee exoskeleton. The state of the exoskeleton was changed by adjusting the pressure of its Pneumatically Actuated Muscle PAM in each trial. Participants were then asked to give a score from 1-5 (1: very easy, 5: very difficult). During the experiment, their brain activity was recorded using an EEG measurement device. 8 people have participated so far, and the acquired data is currently being processed. With this study we hope to find a correlation between the brain activity of participants and their self-reported preference in each state of the device.

We did a literature review that categorizes the use cases of biomechanical models in assistive device development as guiding the design, optimization, control, combining sensory information and evaluation. 

Review outcomes: Biomechanical models can facilitate assistive device design and control. Additionally, using assistive devices to improve existing models, validating simulation results, model-based design, and control for pathological gait and assistance in the frontal plane were also identified as under-researched areas.

We examined current detailed models predicting metabolic cost and found that selecting the right cost function for estimating muscle activation is crucial. Also, using EMG signals with musculoskeletal models improved prediction ability.

Elderly and young gait were compared using the Virtual Pivot Point concept, showing that ground reaction forces in the frontal plane are less focused in elderly gait and decrease in quality with increased speed. Conceptual models and sensitivity analysis suggested that noisy force feedback may be the cause. Potential for clinical analysis and designing assistive devices.

We proposed a bioinspired adaptive model-based controller to aid hip abduction during load-carrying tasks, utilizing GRF and hip abduction angle to adapt the assistance. Our simulations showed reduced metabolic costs during walking with and without load carrying.

Short background: Emotions and cognitions strongly regulate and affect our body movements and relate to our body schema. When locomotion is altered and in states when individuals receive an assistive device (prosthesis or orthosis), (daily) dynamics of affective processing as well as an interaction of expression of emotions through movements may hinder an adaptive integration of the assistive system in the body schema. 

Aims: To apply a mobile-based application (EMA) to monitor and record sensitive and dynamic emotional, cognitive, and behavioral factors in daily life in the area of embodiment and relate those to advanced VR- and sensor-based assessment tools and measures. 

Developments and outcomes so far: 1) Implementation of an EMA design along with VR-based estimates of proprioceptive accuracy and distortions via embodying an avatar with shifted limb positions started, 2) transferred into a more more clinically oriented EMA design in patients with cerebral palsy, and 3) adaptation to prostheses in amputees planned. 

 

Preliminary results (5 young and healthy subjects): All subjects were able to find an assistance pattern that felt optimal to them within 13 min (9.9 ± 0.8 min), which is significantly faster than state-of-the-art human-in-the-loop optimization approaches. The metabolic rate while walking with the self-tuned assistance was reduced by 14.8 ± 1.2 % compared to walking with the zero-torque condition (exoskeleton turned off), which is comparable to the metabolic reduction achieved in other hip exoskeleton studies.

by April 14, 2003. This will help me to prepare my presentation at the LokoAssist symposium. 
Thank you so much for your support!
All the best,
André

Outcomes/Work in progress: 

§  Systematic literature review on prosthesis embodiment as both a bachelor thesis and own research --> The findings will be written in the form of a journal paper and sent to suitable journals or conferences (work in progress at the moment)

§  Study 1: Exploratory study on personality traits and body image of amputees

o   The focus of the study lies on the relationship between personality traits, perceived body image, and prosthesis-related data 

o   Survey period: 10.04.2023 – 15.05.2023

In planning:

§  Study with intelligent crutches (available in our lab) in order to identify the degree of leg strain and find the optimal value for it, individual preferences and expectancy

To be able to understand the beneficial effects of FES, the primary objective of this study is to evaluate the immediate and training effects of FES on gait function. The second and third objectives are to show the effects of FES on dual-task ability while walking and on proprioception. Furthermore, we want to evaluate the effects of FES on the patient’s quality of life in their daily life via Patient Reported Outcome Measures. 

A prospective exploratory cohort study will be performed on 30 adults with unilateral foot drop of central origin. Patients, beginning their FES treatment, aged between 18-60 years, with the ability to walk independently without support will be included in the study. All participants will undergo twelve weeks of conventional FES treatment. At the beginning of the treatment (T1) and after twelve weeks (T3), functional and clinical outcomes will be captured. Additionally, during the twelve weeks (T2) Patient Reported Outcome Measures via ambulatory assessments will be captured to evaluate the effects of FES on the patient’s daily life. The FES device is stimulating at least the peroneal nerve during swing phase. Reference data of 15 unaffected individuals will be considered.

In terms of the immediate orthotic effect of FES OFF vs FES ON, early results of two patients for T1 show an increase in gait velocity during normal and dual-task walking, a decrease in cognition rate and an insufficient increase in dorsiflexion during swingphas.

Changes of speed and cognition rate during dual-task walking with FES could be first signs that FES plays an important role in changing the patients ability to perform additional tasks at the same time. To be able to perform dual-task abilities is crucial to interact with the environment sufficiently and therefore decrease chances of falling during daily life.