Two-Degree-of-Freedom Controller Design Based on a Data-Driven Estimation Approach

Data-driven control design is a method to create and tune controllers directly from the initial experimental data without a mathematical model to be controlled. Tracking and disturbance suppression are necessary to control real systems. A two-degree-of-freedom (2DOF) control system is effective to simultaneously enhance the performances of both. This study proposes a direct data-driven tuning method for the controller parameters of a 2DOF control system using only one-shot initial experimental data without mathematical modeling of the controlled object. The proposed approach improves the tracking and disturbance suppression performances by utilizing an estimation method in which the sensitivity function and the closed-loop transfer function are identified after updating the parameters in the time domain. Specifically, the closed-loop response and control input are estimated after updating the parameters, realizing efficient control system design because the control performance can be evaluated prior to implementation. To validate the effectiveness of the proposed method, a simulation for a mechanical system and an experiment for motor control are performed. The proposed method can estimate the response and control input of a 2DOF control system after updating the parameters by offline computations. The optimal control parameters can be obtained to enhance the tracking and disturbance suppression performances.