Enhanced 2-DOF PID Controller Tuning Based on an Uncertainty and Disturbance Estimator With Experimental Validation

In this paper a novel tuning procedure for Two-Degree-of-Freedom (2-DOF) PID controllers is proposed. The tuning methodology is based on an Uncertainty and Disturbance Estimator. As a result, an equivalent 2-DOF PID controller with simpler tuning rules is obtained. One advantage of the proposed method is that tracking performance and disturbance rejection can be accommodated separately in control synthesis. Moreover, the trade-off between disturbance rejection and robustness can easily be adjusted by tuning a single parameter without affecting the desired set-point tracking specifications. Numerical comparisons with well-known tuning methods are performed to illustrate the advantages of the proposed method. Finally, the effectiveness of the proposal is experimentally validated in an open-loop unstable plant consisting of a test-bed quadrotor platform.