Guaranteed-cost active disturbance rejection control for uncertain systems with an integral controller

Guaranteed-cost active disturbance rejection control (ADRC) for uncertain systems is investigated in this study. Firstly, an integral action is introduced in the framework of ADRC to measure and reduce the tracking error. Then, a robust stability condition is presented, and a quadratic cost function where the tracking error is appearing explicitly is used for ADRC performance assessment. The cost bound is formulated by linear matrix inequality and optimised to obtain controller parameters. Full-dimension extended state observer is used, and thus, the proposed strategy is applicable to an uncertain system that allows relative-degree varying or right-half-plane zero. Finally, the validity of the proposed method and its advantages is demonstrated through the simulations of comparative examples and experiments on a motor speed control system.