Feedback control of cycling in spinal cord injury using functional electrical stimulation

This thesis is concerned with the realisation of leg cycling by means of FES in SCI individuals with complete paraplegia. FES lower-limb cycling can be safely performed by paraplegics on static ergometers or recumbent tricycles. In this work, different FES cycling systems were developed for clinical and home use. Two design approaches have been followed. The first is based on the adaptation of commercially available recumbent tricycles. This results in devices which can be used as static trainers or for mobile cycling. The second design approach utilises a commercially available motorised ergometer which can be operated while sitting in a wheelchair. The developed FES cycling systems can be operated in isotonic (constant cycling resistance) or isokinetic mode (constant cadence) when used as static trainers. This represents a novelty compared to existing FES cycling systems. In order to realise isokinetic cycling, an electric motor is needed to assist or resist the cycling movement to maintain a constant cadence. Repetitive control technology is applied to the motor in this context to virtually eliminate disturbance caused by the FES activated musculature which are periodic with respect to the cadence. Furthermore, new methods for feedback control of the patient’s work rate have been introduced. A one year pilot study on FES cycling with paraplegic subjects has been carried out. Effective indoor cycling on a trainer setup could be achieved for long periods up to an hour, and mobile outdoor cycling was performed over useful distances. Power output of FES cycling was in the range of 15 to 20 W for two of the three subjects at the end of the pilot study. A muscle strengthening programme was carried out prior and concurrent to the FES cycling. Feedback control of FES assisted weight lifting exercises by quadriceps stimulation has been studied in this context

Master of Science

thesisIncreased demand for powered wheelchairs and their inherent mobility limitations have prompted the development of omnidirectional wheelchairs. These wheelchairs provide improved mobility in confined spaces, but can be more difficult to control and impact the ability of the user to embody the wheelchair. We hypothesize that control and embodiment of omnidirectional wheelchairs can be improved by providing intuitive control with three degree of freedom (3-DOF) haptic feedback that directly corresponds to the degrees of freedom of an omnidirectional wheelchair. This thesis introduces a novel 3-DOF Haptic Joystick designed for the purpose of controlling omnidirectional wheelchairs. When coupled with range finders, it is able to provide the user with feedback that improves the operator's awareness of the area surrounding the vehicle and assists the driver in obstacle avoidance. The haptic controller design and a stability analysis of the coupled wheelchair joystick systems are presented. Experimental results from the coupled systems validate the ability of the controller to influence the trajectory of the wheelchair and assist in obstacle avoidance

介助者の自律駆動規範モデルを用いた介助用車いすの補助動力制御

関西大

Design Principles for FES Concept Development

© Cranfield University 2013. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner.A variety of pathologies can cause injury to the spinal cord and hinder movement. A range of equipment is available to help spinal injury sufferers move their affected limbs. One method of rehabilitation is functional electrical stimulation (FES). FES is a technique where small electrical currents are applied to the surface of the user’s legs to stimulate the muscles. Studies have demonstrated the benefits of using this method and it has also been incorporated into a number of devices. The aim of the project was to produce a number of designs for a new device that uses FES technology. The project was completed in conjunction with an industrial partner. A review of the literature and consultation with industrial experts suggested a number of ways current devices could be improved. These included encouraging the user to lean forwards while walking and powering the device using a more ergonomic method. A group of designers were used to produce designs that allowed the user to walk with a more natural gait and avoided cumbersome power packs. The most effective of these designs were combined to form one design that solved both problems. A 3-dimensional model of this design was simulated using computer-aided design software. Groups of engineers, scientists and consumers were also invited to provide input on how a new device should function. Each of these groups provided a design that reflected their specific needs, depending on their experience with similar technology. Low level prototypes were produced of these designs. A group of designers were also used to design concepts for a functional electrical stimulation device based on an introduction given by industry experts. Each of the designs was presented to experienced professionals to obtain feedback. A set of guidelines were also produced during the project that instructed how to create the designs

Stroke-related Changes in Neuromuscular Fatigue of the Hip Flexors and Functional Implications

Objective: The aim of this study was to compare stroke-related changes in hip flexor neuromuscular fatigue of the paretic leg during a sustained isometric submaximal contraction with those of the nonparetic leg and controls and to correlate fatigue with clinical measures of function. Design: Hip torques were measured during a fatiguing hip flexion contraction at 20% of the hip flexion maximal voluntary contraction in the paretic and nonparetic legs of 13 people with chronic stroke and 10 age-matched controls. In addition, the participants with stroke performed a fatiguing contraction of the paretic leg at the absolute torque equivalent to 20% maximal voluntary contraction of the nonparetic leg and were tested for self-selected walking speed (10-m Walk Test) and balance (Berg). Results: When matching the nonparetic target torque, the paretic hip flexors had a shorter time to task failure compared with the nonparetic leg and controls (P \u3c 0.05). The time to failure of the paretic leg was inversely correlated with the reduction of hip flexion maximal voluntary contraction torque. Self-selected walking speed was correlated with declines in torque and steadiness. Berg-Balance scores were inversely correlated with the force fluctuation amplitude. Conclusions: Fatigue and precision of contraction are correlated with walking function and balance after stroke

Fatigue in Children and Adolescents with Duchenne Muscular Dystrophy

Fatigue was recently reported to be the largest predictor of poor health-related quality of life (HRQOL) in children and adolescents with Duchenne muscular dystrophy (DMD). The objectives of this thesis were to describe fatigue from patients’ and parents’ perspectives and to explore associations of patient characteristics with fatigue in children and adolescents with DMD using a multicentre cross-sectional study design. Eligible patients and their parents were identified via the Canadian Neuromuscular Disease Registry and received mailed paper questionnaires. Children and adolescents with DMD experienced greater fatigue compared to healthy controls from published data. Fatigue was a significant issue in children and adolescents with DMD across all disease stages. Sleep disturbance symptoms, depressive symptoms and functional ability were associated with fatigue. Physical activity level was not associated with fatigue. These findings warrant future research aimed at understanding the determinants of fatigue and developing therapeutic strategies to reduce fatigue and improve HRQOL

Development and assessment of novel methods of exercise testing during treadmill gait in incomplete spinal cord injury

The main study of this thesis monitors changes in cardiopulmonary fitness, peak voluntary force and CAR of the quadriceps and hamstring muscles, and lower limb BMD in two incomplete SCI subjects who participated in a 20-week BWS treadmill training (BWSTT) programme. The main outcomes of the BWSTT study were: a substantial improvement in performance parameters (training work rate, peak work rate (WRpeak) and the distance walked in 15 minutes), an overall increase in VO2peak and peak heart rate (HRpeak), a substantial decrease in ?VO2/?WR and a decrease in the VO2 and HR associated with a step increase in work rate. Accurate identification of an LT, tVO2, and the voluntary peak force and CAR was not established. An increase in lower limb BMD was not identified in the subject who was 2 years post injury. However, encouragingly an increase was shown in the trabecular BMD of the right and left tibia of the subject who was 14.5 years post injury. A novel non-robot-assisted treadmill IET which incorporated nonlinear, equally smooth increases in both speed and gradient was also developed and assessed. The benefits of BWSTT in those with an incomplete SCI have been highlighted in this thesis. It has also been shown that cardiopulmonary exercise testing can potentially be utilised in this population. Whether or not the IETs assessed throughout this thesis provide a true indication of the subjects’ actual cardiopulmonary capacity is debatable due to limitations in their gait pattern and lower limb muscle fatigue. Therefore, the accurate detection of an LT and tVO2 may be key to determining improvements in cardiopulmonary fitness in this population. It is therefore suggested that further study in a larger subject group be carried out to determine the repeatability and reliability of the outcome measures obtained