Mosfet converter-fed position servo system with sliding mode control

Sliding mode control is an effective means to keep a system insensitive to parametric variations and disturbances. In the conventional sliding mode control applied to position servo systems, the sliding mode regime is restricted near the origin, and therefore insensitivity cannot be ensured throughout an entire response. This paper presents a new method in which a sliding curve is used instead of a straight line. The sliding curve is defined in such a way that in general the system responds following a max acceleration curve, then a max speed curve and finally a max deceleration curve. Experimental results confirm that the new method can keep the system robust completely throughout a transient response, which demonstrates the advantage of the proposed sliding curve over the conventional sliding mode strategy.