Extended-State-Observer-Based Tracking Control for Motor-drive Systems with State Constraints and Unknown Disturbances

In order to address the state constraints of the motor-drive systems (MDS) with the unknown disturbances, a funnel control strategy based on extended state observer (ESO) is proposed. The unknown disturbances (modeling error, nonlinear frictions and unknown disturbance torque) and unknown speed in the MDS were estimated by a time varying gain ESO, which has better transient behavior of the estimations. The original system was transformed into a constrain-free system by two funnel variables, and then the evolution of the position tracking error in a funnel region and speed in a constant boundary were achieve by a dynamic surface control. Furthermore, the feasibility conditions of virtual control laws in barrier Lyapunov function (BLF) were removed. The convergence of the closed-loop control system was illustrated by the Lyapunov theory. Simulation results verify the effectiveness of the proposed funnel control method.