Serial Elastic Actuators Torque Control Approach Based on Active Disturbance Rejection Control

Serial Elastic Actuator (SEA) system attracts much attention recent years in robotics research. The control methods for SEA is studied especially considering the unknown and time-varying dynamic load. Most methods are based on the predetermined nominal dynamics of the SEA system. However, imperfect dynamics and time varying reference torque make the torque tracking problem difficult. In this paper, the Active Disturbance Rejection Control (ADRC) method is proposed to solve the above problems. The dynamics of SEA is simplified by considering the dynamics of load as the unknown disturbance. An Extended State Observer (ESO) is designed to identify the model uncertainties. The control framework could observe and reject the disturbance effectively. Finally, the effectiveness of the ADRC based torque controller is verified and compared with traditional cascade PID controller by using MATLAB/ADAMS Co-simulation, especially considering the case that SEA is implemented in a vertical plane which makes the dynamics much more complicated.