Design and Implementation of an Electro-optical Tracking Servo System Via Composite Nonlinear Control Approach

In a typical electro-optical tracking system, two types of controllers are used for acquisition and tracking modes. This leads to the problem of mode switching. The direct switching of the parallel channels might result in an unstable system, or in a system with small stability margins and, therefore, producing large transient error. This paper proposes a composite nonlinear control scheme which can perform all the above functions to shorten the settling time by reducing the overshoot caused by the integrator, without degradation of other performance specifications. This control law not only increases the speed of closed-loop response, but also improves the settling performance.