Stability Control for a Walking-Chair Robot with Human in the Loop

Abstract

In this paper, a human-machine shared stability control strategy is proposed for a walking-chair robot with human in the loop. We consider the human in the loop as the torso of the robot and human movement as disturbance control to the system stability. Then the safe input regions for joints are given based on the zero moment point(ZMP) criterion. The control inputs to the system are defined according to the safe input regions. When the system state stays in the safe region, the control input select the human input. When the system state leaves the safe region, a safe control is determined according to the safe input set and the human input, which changes with the different system states. The control input is determined to be the combination of the human input and the safe control. Smooth transition from human input to snapped safe input is achieved so as to guarantee the rubust of the stabilitiy control. Simulation is done to analyze the influence of human input on system stability. The results show that the strategy increase the system stability with human in the loop.