Upper Limb Exoskeleton – ‘AESR’

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Group Design Project
3D Printed Power-Assisted Upper Limb Exoskeleton with Myoelectric Controlled Functions for Stroke Rehabilitation
Group Members
Samuel Gan, Thanh Trung Mai, Erik Meilak, James Milligan, James Nash, Patrick Ng, Matthew Story

Supervisors
Professor Liudi Jiang, Dr. Yi Huang

There are approximately 1.2 million stroke survivors in the UK. Early and effective neuro-rehabilitation is key to reducing disability and increasing recovery rate post-stroke. Various methods of stroke rehabilitation methods and devices have been developed, including robotic exoskeleton systems - orthotic devices with corresponding links to the human joints. Arm Exoskeleton for Stroke Rehabilitation (AESR) was designed and manufactured as a low-cost power-assisted exoskeleton for stroke rehabilitation of the upper limb. The main advantage of the exoskeleton is its low cost, since commercial exoskeletons cost upward of £50,000. Stroke patients often have muscle weakness and lack muscle co-ordination on one side of their body. AESR guides the patient’s weak arm to perform therapeutic motions. The control utilised myoelectric sensors (EMGs) to detect muscle activity as well as inertial measurement units (IMUs). These provided an angular position with the strong arm, and a proportional speed control relative to strength, totalling in a closed loop system that performs better the more effort that is input. Components were optimised using FEA (Finite Element Analysis) and 3D-printed from PLA or ABS material. The connecting rods are made from carbon fibre and the supporting back plate is made from aluminium. Linear actuators powered the movement at the elbow and shoulder joints. Several safety measures were introduced, both mechanical and electrical. Control testing was performed to analyse and optimise its performance while mechanical testing was performed using strain gauges to ensure safety and strength requirements were met.

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