Lower body exoskeleton for walking gait assistance and performance augmentation using compliance controlled actuators

Costa, NRS

Abstract

Successful motor rehabilitation after stroke or traumatic brain/spinal cord injures requires a
highly intensive and task-specific therapy-based approach. Currently many patients with these
types of pathologies are confined to wheelchairs, which results in a sedentary lifestyle causing
other critical secondary health conditions and increased dependence on a carer. Increasing
evidence has shown that locomotor training can reduce the incidence of these secondary
pathologies, but the physical effort required from patients and the cost, time and intensive load on
the physiotherapists involved in these regular locomotor walking exercises is such that there is poor
compliance. A new range of intelligent assistive machines may offer an alternative and more
efficient solution to promote motor rehabilitation recovery and obtain a better understanding of
human motor control required for these subjects.
This thesis reports on the complete development from design, and construction to the testing
and performance analyses of a new "human friendly" 10-degree of freedom lower body
exoskeleton for walking gait assistance and also generic human force augmentation. The twin
wearable 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-like
contact, taking advantage of their inherent nature which weakens linearly as it contracts and as
such can be considered a soft and biomimetic actuation system. The combination of a highly
compliant 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 operation
for patients. This capacity to "replicate" the function of natural muscle and inherent safety is
extremely important when working in close proximity to humans particularly those suffering a
disability. These actuators are driven from a developed novel power energy source that has
excellent autonomy potential.
An integrated system comprising all the components in a pMA controller network
architecture of interconnected microcontrollers (uCs) and a highly advanced wireless interface
has 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 and
actuators can be combined to generate a variety of walking gaits or strategies needed for a highly
flexible/low weight clinically viable rehabilitation exoskeleton. Further more, the application of
this technology in an advanced rehabilitation centre with active partial body weight support over a
treadmill with automatic position and velocity control demonstrated that is has the potential to
greatly improve the therapeutic approach and rehabilitative protocols for paraplegic patients and
neurologic 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 secondary
health care and to obtain a better understanding of human motor walking gait.

Citation

Costa, N. Lower body exoskeleton for walking gait assistance and performance augmentation using compliance controlled actuators. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Aug 17, 2021
• Additional Information: Funders : Escola Superior de Tecnologia e Gestao of the Institute Politecnico de Leiria;Fundasao para a Ciencia e a Tecnologia (FCT); Projects : Programa Operacional Ciencia, Tecnologia, Inovacao;Programa Operational Sociedade de Informacao
• Award Date: Nov 1, 2008