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Finite time motion control for a launching platform based on sliding mode disturbance observer

A kind of launching platform driven by two permanent magnet synchronous motors which is used to launch kinetic load to hit the target always faces strong external disturbance such as the air current impulsion which would degrade their tracking accuracy greatly. In this article, the position control problem of a launching platform with strong disturbance is studied based on the finite time control technique. A sliding mode disturbance observer is proposed to observe the disturbance, based on which a finite time control technique is proposed for position loop. Rigorous mathematical analysis is given for the closed-loop system performance in the presence of disturbances. The experimental results show that this method not only makes the position tracking error of the closed-loop system converge faster but also makes the boundary of steady-state error smaller than that of the conventional proportional–integral–derivative control scheme and sliding mode control scheme, which means the closed-loop system has stronger anti-disturbance property.