Robust control of DC motors based on disturbance estimation

Unmodeled disturbances always exist in physical servo systems and degrade their tracking performance. In this paper, a practical method named robust control based on disturbance estimation is proposed and integrated for high-accuracy motion control of a dc motor. A finite-time disturbance observer (FTDO) for the unmodeled disturbances is designed and disturbance estimation is used to compensate the unmodeled disturbances via a feedforward cancellation technique. While robust control ensures the global robustness of the proposed controller. Moreover, the controller theoretically guarantees a prescribed tracking performance in the presence of various uncertainties via a novel Lyapunov function, which is very important for high-accuracy control of motion systems. Simulation results show that the proposed controller can estimate disturbances of the load accurately and present the high-performance nature of the proposed control strategy.