Design of a gait assistant exoskeleton for individuals with lower limb impairments

Abstract

The goal of the research was to investigate the design of a gait aid that could help individuals with lower limb impairments to support the rehabilitation of the walking function in individuals with certain types and classes of lower limb impairments.

After reviewing different types of lower limb impairments, it was established that in many cases this is a non reversible condition that renders muscles in the legs useless either by physically impairing them or by severing the control mechanisms that allow them to be flexed and relaxed at will. This review process was important in validating the concept of the gait aid as at present a cure for this condition is not available.

The research used the analysis of human gait and bipedal robotic gait to develop the concept of an exoskeleton based on a telescopic knee, which could be integrated with an appropriate control system in which the user provides a control input via the crutches. This unique approach to restoring the walking function can be seen as one of the most representative contributions of the project, alongside the methodology developed to analyse the movement profiles and the comparison in between the generated trajectories. The results of the research are a full analysis of the proposed system together with a ¹/₄  scale model of a single leg incorporating a telescopic knee. 
The initial assumption that an exoskeleton could replace wheelchairs as the main stream aid for mobility in this population also had to be completely revised based on the user centred approach and changed into a different one in which a wheelchair contains the exoskeleton that can detach itself and allow a short stroll nearby the wheelchair.

The wheelchair would then contain the bulk of the energy storage and anything else that is not absolutely necessary for the exoskeleton in order to minimise the weight of the structure. The development of the full size exoskeleton was declined in favour of a therapeutic approach whereby the exoskeleton design procedure is used to investigate an application for a robotic therapeutic rehabilitation device for the lower limbs. This research have been used to extend that initial concept to that of a full-scale machine to be used for the rehabilitation of the lower limbs while employing a control strategy integrated within a telehealth environment.

Finally twelve papers have been produced¹ taking into account both projects put together, in fact although the dissertation only discusses that part of the research pertinent to the exoskeleton and how it led to the NeXOS project, it is in many ways easier to understand the research efforts of the past six and a half years as just one big project.

¹The complete text of the papers can be found on Appendix C and digitally in the accompanying DVD-ROM.

Date of Award	Oct 2006
Original language	English