Development of a Compact Lower-Limb Exoskeleton for Walking Assistance: A Case Study

Abstract

Lower-limb exoskeletons are an effective means to provide paraplegic and hemiplegic individuals with the ability to walk upright. A lot of studies about lower-limb exoskeletons have been developed to assist the impaired populations. However, the existing devices are still too technically complex and expensive for practicality. In this paper, a compact lower-limb exoskeleton for walking assistance is developed, in which a steel-cable actuator is specially designed. In order to accomplish the different tasks presented to gait generation, a control method with multiple stages is employed. In this approach, four basic states and seven intended motions are designed for the finite-state machine. In addition, the reference trajectories of these intended motions are presented and fitted by a modified first-order polynomialfitting method. Preliminary motion tests of the exoskeleton with three healthy subjects are performed. The results verify the effectiveness of the system design and the gait-generation approach proposed in this paper. The overall exoskeleton system is compact and the corresponding operations are convenient and reliable.