Multicontact Safety-Critical Planning and Adaptive Neural Control of a Soft Exosuit Over Different Terrains.

Abstract

Many previous works on wearable soft exosuits have primarily focused on assisting human motion, while overlooking safety concerns during movement. This article introduces a novel single-motor, altering bi-directional transfer soft exosuit based on impedance optimization and adaptive neural control, which provides assistance to the lower limbs using Bowden cables. This innovative soft exosuit integrates control barrier functions into the impedance optimization, allowing multiple safety constraints to be considered simultaneously, enabling the system to adaptively learn the impedance of the human ankle joint by analyzing the measured interaction forces at the ankle joint, so that the updated reference trajectories comply with safety requirements. To effectively track the updated reference trajectories, we have introduced an adaptive neural controller based on the integral barrier Lyapunov function. This controller is designed to perform the control task under strict safety constraints. The stability of this control approach is meticulously demonstrated through extensive Lyapunov analysis. In contrast to traditional soft exosuits designed purely for assistance, the key advantage of this technology is its ability to adapt to different terrains while ensuring the safety of human movement during assistance. Through experimental testing, we obtain average tracking errors of 0.0062, 0.0062, and 0.0063 rad for flat, grass, and gravel surfaces, respectively, demonstrating the effectiveness of the proposed strategy.