Abstract
Due to the increasing elderly population and the growing demand for healthy ageing, there has been a surge of interest in wearable assistive technologies to support mobility and balance. Some elderly people who fear falls tend to get excessive and continuous support from hands-operated devices (such as canes and walkers), which may lead to user passivity, diminishing motor engagement and potentially hindering neuromuscular adaptation. During balance recovery following assistance, the user's effort still remains critical to prevent over-reliance on assistance, so the concept of assist-as-needed (AAN) should be incorporated into the design of assistive devices. In this paper, we proposed an adaptive compliant support strategy based on variable admittance control for the wearable walking assistive device. The compliance of the RSL's linear actuator is modulated by a nonlinear damping term to provide both soft support to encourage user effort under small perturbation, and strong support to resist larger perturbation. Support effectiveness was first evaluated through simulations under disturbance and subsequently investigated in a physical prototype to discuss the practical effect of the proposed strategy. This work aims to enhance the safety and adaptability of wearable assistive devices to provide compliant and suitable support.
