Position control of Series Elastic Actuator based on feedback linearization and RISE method
Series Elastic Actuator (SEA) is a powerful device in the area of human-machine collaboration, but it still suffers from difficult position control issues, mainly because the variables and order of dynamics become twice that of the rigid one. Therefore, an efficient approach is proposed to solve this problem in this paper. The approach design is divided into two steps: feedback linearization (FL) and robust integral of sign of error (RISE) feedback controller design. Specifically, the dynamics of SEA is first proved to be feedback linearizable in the presence of damping term of motor side. However, FL requires exact knowledge of the system model, and the expression of last channel is too complicated; which make the controller sensitive to uncertainties. Therefore, a RISE feedback controller is adapted to address these issues, and the closed loop stability analysis is established. Simulation results illustrate that the proposed method can achieve the control objective and is robust to parameters uncertainty and matched external disturbance.