Considering that there are time-varying inertia, torque disturbance and unmodeled dynamics in high accuracy
speed control systems, a composite controller consisting of PI controller, compensator based on recursive least square
algorithm with forgetting factor(FRLS), compensator based on extended state observer(ESO) and robust controller is
designed. FRLS is used for identifying time-varying parameters, and ESO is applied for observing errors of parameter
identification and unmodeled dynamics. The stability of the closed-loop system is analyzed. Simulation results show the
effectiveness of the composite speed controller.