WINNER
Design Excellence Award

Powered Lower Limb Exoskeleton

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Design Excellence Award, Group Design Project
Design and development of a low cost lower limb exoskeleton for stroke physiotherapy
Group Members
Jonathan Howard, Claire Pinington, Ryan Tan, Eugene Teoh, Joseph Wainwright, Johnathan Yeo

Supervisors
Professor Liudi Jiang, Dr. Andrew Chipperfield

Powered exoskeletons have been developed for use in the medical industry in order to assist with patient rehabilitation. Using exoskeletons reduces rehabilitation time, while improving muscle function by allowing rehabilitation exercises to start earlier by providing an assistive force during movement. This support allows patients to undertake physiotherapy exercises they would otherwise lack the strength for. Strokes are one of the largest causes of disability; with over 600 thousand stroke patients living with a disability in the UK and 72% experiencing lower limb weakness. Current exoskeletons available for use in rehabilitation and medical fields are extremely expensive, in the region of over £100 000 at minimum, and so are unavailable for use on patients with the NHS.

The aim of the project was to design and build a low cost lower limb powered exoskeleton which is capable of assisting patients with walking and physiotherapy within a budget of £1600. Mechanical joints were developed around motors that were able to provide rotational movement of both the knee and hip joints. Interviews were conducted with stroke physiotherapists to help identify end user requirements. Prototype joints were computationally designed and then 3D printed to help identify improvements that could be made. The final joint designs were manufactured out of aluminium and lightweight carbon fibre rods were used to provide structural support of the mechanical frame. Attachment to the patient was achieved using knee and hip straps, while an additional ankle support was included to avoid ankle drop during patient rehabilitation.

The exoskeleton was controlled using accelerometer sensors attached to a physiotherapist’s leg; the patient’s leg, which the exoskeleton was attached to, would then track the leg movements of the physiotherapist through movement of the exoskeleton. This allowed the physiotherapist to directly control the movements of the patient’s leg. Low cost sensors were combined with a cheap and user friendly microcontroller that controlled the movements of the exoskeleton. The exoskeleton was able to accurately track the full range of knee movements at low speed and the majority of hip movements.

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