Integrated sliding mode autopillot-guidance for dual-control missiles

An integrated autopilot and guidance algorithm is developed, using the sliding mode control approach, for a missile with forward and aft control surfaces. The integrated controller can account simultaneously for the guidance and autopilot requirements using the additional degree of freedom offered by the dual-control configuration. Based on guidance considerations, the zero-effort miss, encountered in differential games guidance solutions, is used as one of the sliding variables in the proposed control scheme. Selection of the second surface, required due to the dual-control configuration, is based on autopilot design considerations. Restraining the system to the zero-effort miss surface guarantees zero-miss distance, whereas remaining, on the second surface provides a damped response. The performance of the integrated dual controller is evaluated using a two-dimensional nonlinear simulation of the missile lateral dynamics and relative kinematics. The simulation results validate the design approach of using zero-effort miss and the flight-control based sliding surfaces to attain high-accuracy interception in engagements against highly maneuvering targets.