Sliding mode variable structure control for tank servo system based on disturbance observer

A two-loop control approach using the disturbance observer (DOB) as inner loop and the sliding mode variable structure control (SMVSC) as outer loop was proposed to deal with the external disturbance, the uncertainty of inner parameters existed in the tank gun servo system. Through analysis, the robustness and performance of the DOB system in the name of two-degree-freedom, DOB compensates large perturbation and uncertainties by designing an adequate low pass filter, further the chattering of SMVSC can be reduced. Also SMVSC eliminates the DOB's error, and satisfies the tracking performance. Finally, the approach is used in the tank gun servo system. Computer simulations show that the tracking accuracy is much better and the control system has strong adaptability and robustness.