Multiobjective optimization of Fuzzy Logic Scheduled Controllers for missile autopilot design

This paper describes the design of a Fuzzy Logic Scheduled Controllers used for side-slip velocity control of a missile autopilot design. A multi-objective evolutionary algorithm is used to determine the membership function distribution of the fuzzy trajectory controller within an outer loop control system. Scaling factors of the FLC inputs and outputs for each required demand are obtained by using a polynomial fit for a large range of multiple velocity demands (1g,5g,10g,15g-lateral acceleration equivalent). The design meets mulitple objectives related to closed loop performance such as: steady state error, overshoot, settling and rise time. Multiple solutions are obtained simultaneously by using nondominated sorting for forming the Pareto front, combined with a reference point approach to incorporate preference information into the GA to direct the search towards feasible desirable areas which satisfy specific values of the objectives. Simulationn results are presented showing the fuzzy gain surface and extreme models in the multiple model population.