Stable Crawling Policy for Wearable SuperLimbs Attached to a Human with Tuned Impedance

A control algorithm that allows a human model to crawl using a pair of supernumerary robotic limbs (SuperLimbs) is presented. The human model and SuperLimbs are coupled by a compliant harness. This work is inspired by the need for wearable robotic systems that can support workers engaged in fatiguing tasks. The walking policy is developed based on Lyapunov analysis. The volume of the region of attraction (ROA) of the system is used to quantify robustness and identify the optimal harness compliance. Simulation experiments are used to verify the performance of the algorithm. The presented formulation allows us to guarantee stable locomotion under nominal conditions and define robustness against modeling error and perturbations. This study is also the first, that the authors are aware of, to address cooperative crawling between a human and a wearable robotic system with state feedback.