Feedback linearization speed-tracking control of linear servo system based on sliding mode observer

The rapid precision tracking of speed is required in many high speed and high precision linear servo systems,but it is difficult to control because of the nonlinearity of the system model and the coupling between the variables.The variable processes of the current and speed is relative propinquity in the time scale,therefore the magnetic field directional vector control method cannot simply be used for the static decoupling,otherwise the quality of speed tracking will be damaged by the nonlinear coupling between the current and speed.The feedback linearization method is used to achieve the precision linearization and dynamic decoupling of the permanent-magnet linear synchronous motor(PMLSM) servo system.The nonlinear coordinate commutation and nonlinear feedback are used for decoupling the servo to unattached linear current sub-system and speed sub-system.A sliding mode extended observer is designed to realize the robust observation of the speed,acceleration and unknown load resistance necessary for speed-tracking control.Furthermore,the stability of the speed-tracking control closed loop system constituted of feedback linearization control and sliding mode observer is analyzed using Lyapunov stability theory.Some simulation results show that this control scheme makes the PMLSM servo system have good robust speed-tracking performance.