An optimal type-1 servo control mechanism for flight-path-rate-demand lateral missile autopilot

This brief proposes an optimal type-1 servo scheme for autopilot design for a class of rear-controlled, flight-path-rate-demand, guided, lateral missiles. The rear-controlled missiles pose significant challenges in the autopilot design due to their non-minimum phase (NMP) characteristic and open-loop instability. The control objective is to design a flight-path rate demand, two-loop, lateral missile autopilot minimising the initial undershoot in the time response (due to the presence of NMP zero). An existing linearised model of a rear-controlled missile has been considered in this paper. The proposed scheme employs a reduced-order observer for generating some of the states of a missile that are difficult to measure in practice. The LQR principle has been used to find the optimal feedback gains based on the given time-domain performance criteria. An exhaustive Matlab simulation study has been carried out to demonstrate the effectiveness of the proposed autopilot scheme in achieving the desired control objectives. The simulation results suggest that the optimal type-1 servo scheme performs better than the conventional frequency-domain design methodologies.