Adaptive Oscillator-Based Robust Control for Flexible Hip Assistive Exoskeleton

Abstract

This study aims to develop a wearable robotic exoskeleton to provide walking assistance for elderly and disabled people with weakened skeletal muscles. Our developed hip exoskeleton is powered by two electrical series elastic actuators covering both hip extension/flexion joints. For exoskeleton control, motion intention perception, delivering appropriate force, and flexible human-exoskeleton interaction still remains challenging. To this end, this letter proposes an improved gait synchronizer driven by the only hip angular velocity to synchronize gait phase and further estimate gait features. To adapt to the ever-changing gait, the commanded torque is further modulated with estimated walking states and speed. The sEMG results from six subjects demonstrate its effectiveness on movement assistance, i.e., reducing muscle activation efforts for 4 km/h walking and upstairs.