Robust controller design for the cooperative control of lower extremity rehabilitation robot

In this paper, a robust controller design approach is proposed for Lower Extremity Rehabilitation Robot (LERR) with automatic gait adaption. Based on the developed LERR dynamic model, the robot system is first decoupled into three independent second-order integral sub-systems using invertibility decoupling method. Then a robust PID controller is proposed for each sub-system to deal with the uncertainty in the robot system modeling by converting the PID controller design problem into a mixed H2/H∞ static output feedback multi-objective optimization problem. The adaptive control method is further investigated for a compliant gait trajectory planning. The performance of the designed controller is finally verified in the MATLAB-Adams co-simulation environment to show the effectiveness of the proposed robust control approach. © 2014 SERSC.