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

In this paper, a human-machine shared stability control strategy is proposed for a walking-chair robotwith human in the loop. We consider the human in the loop as the torso of the robot and human movement asdisturbance control to the system stability. Then the safe input regions for joints are given based on the zeromoment 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 stateleaves the safe region, a safe control is determined according to the safe input set and the human input, whichchanges with the different system states. The control input is determined to be the combination of the humaninput and the safe control. Smooth transition from human input to snapped safe input is achieved so as toguarantee the rubust of the stabilitiy control. Simulation is done to analyze the influence of human input onsystem stability. The results show that the strategy increase the system stability with human in the loop.