Lower body exoskeleton for walking gait assistance and performance augmentation using compliance controlled actuators
Successful motor rehabilitation after stroke or traumatic brain/spinal cord injures requires ahighly intensive and task-specific therapy-based approach. Currently many patients with thesetypes of pathologies are confined to wheelchairs, which results in a sedentary lifestyle causingother critical secondary health conditions and increased dependence on a carer. Increasingevidence has shown that locomotor training can reduce the incidence of these secondarypathologies, but the physical effort required from patients and the cost, time and intensive load onthe physiotherapists involved in these regular locomotor walking exercises is such that there is poorcompliance. A new range of intelligent assistive machines may offer an alternative and moreefficient solution to promote motor rehabilitation recovery and obtain a better understanding ofhuman motor control required for these subjects.This thesis reports on the complete development from design, and construction to the testingand performance analyses of a new "human friendly" 10-degree of freedom lower bodyexoskeleton for walking gait assistance and also generic human force augmentation. The twinwearable legs are powered by 20 braided pneumatic Muscle Actuators (pMAs); a new, low mass,high power to weight and volume actuation system. In addition, the pMAs produce a muscle-likecontact, taking advantage of their inherent nature which weakens linearly as it contracts and assuch can be considered a soft and biomimetic actuation system. The combination of a highlycompliant actuation system, with a lower level embedded control system which senses hip, knee,and ankle position, velocity, acceleration and force, produces powerful yet inherently safe operationfor patients. This capacity to "replicate" the function of natural muscle and inherent safety isextremely important when working in close proximity to humans particularly those suffering adisability. These actuators are driven from a developed novel power energy source that hasexcellent autonomy potential.An integrated system comprising all the components in a pMA controller networkarchitecture of interconnected microcontrollers (uCs) and a highly advanced wireless interfacehas been developed to control the actuators and provide sensing, communication and monitoring.Using this topology, it has been demonstrated how the structure, low level control system andactuators can be combined to generate a variety of walking gaits or strategies needed for a highlyflexible/low weight clinically viable rehabilitation exoskeleton. Further more, the application ofthis technology in an advanced rehabilitation centre with active partial body weight support over atreadmill with automatic position and velocity control demonstrated that is has the potential togreatly improve the therapeutic approach and rehabilitative protocols for paraplegic patients andneurologic injured users. This novel powered locomotor trainer aims to promote motor recovery,reducing this effort to a tolerable level encouraging higher levels of exercise, improved secondaryhealth care and to obtain a better understanding of human motor walking gait.
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