Data-Driven Iterative Tuning Based Disturbance Observer Control for Variable Stiffness Compliant Actuator

This paper presents a data-driven iterative tuning based disturbance observer control for the variable stiffness compliant actuator(VSCA). Aiming to improve robustness of the control system for the VSCA after stiffness adjustment, the proposed method realize fast tuning of the perturbation observer parameters based on the principle of iterative feedback tuning, which depends on the input and output data. The mathematical model of VSCA is developed, including the analysis of static stiffness model and dynamics model. The step response experiments is carried out to identify VSCA's transfer function under different excitation currents. A function <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</tex> is constructed with disturbance observer control loop for the second-order delay system. By iterating the parameters in the function L, the disturbance rejection of controller which suffer from changement of stiffness is improved. The effectiveness of the proposed control method is simulated and verified through the simulink module of MATLAB.