ROBUST, GAIN-SCHEDULED AUTOPILOTS FOR MISSILES

THE FUNCTION OF MISSILE AUTOPILOTS IS TO MAINTAIN STABILITY OF THE AIRFRAME OVER THE PERFORMANCE ENVELOPE, PROVIDE ADEQUATE AIRFRAME RESPONSE FOR THE GUIDANCE SYSTEM AND REDUCE SENSITIVITY OF GUIDANCE PERFORMANCE TO VEHICLE PARAMETER VARIATIONS AND DISTURBANCES. THE AUTOPILOTS MUST BE ROBUST TO PREDICTABLE VARIATIONS IN PLANT PARAMETERS ABOUT SOME OPERATING POINT AS WELL AS ACTUAL UNCERTAINTY (WHICH MAY BE SMALLER THAN THE PREDICTED PARAMETER VARIATIONS) IN THE AIRFRAME CONTROL DESIGN MODEL. THESE PROBLEMS ARE APPROACHED FROM TWO DIRECTIONS INTHIS PROPOSAL. THE FIRST INVOLVES THE APPLICATION OF U-SYNTHESIS TECHNIQUES TO DESIGN SEVERAL AUTOPILOTS FOR A GIVEN FLIGHT ENVELOPE. THESE DESIGNS WILL EMPHASIZE ROBUSTNESS TO PARAMETERS THAT VARY AS A FUNCTION OF TIME AND MODELLING UNCERTAINTIES IN THE CONTROL DESIGN MODEL. THE SECOND DIRECTION OF THE RESEARCH IS TO DIRECTLY DESIGN FOR A SINGLE AUTOPILOT FRAMEWORK WHICH SCHEDULES AS A. FUNCTION OF SEVERAL VARIABLES. THREE NOVEL APPROACHES TO GAIN-SCHEDULING ARE PROPOSED FOR DESIGN. THESE ARE: ROBUST, GAIN-SCHEDULED, STATE-FEEDBACK WITH QUADRATIC STABILITY; STATE-SPACE U UPPER BOUND USING OBSERVERS AND STATE FEEDBACK; AND D - K ITERATION WITH A GAIN SCHEDULED STRUCTURE. THE GOAL IS TO DESIGN MORE ROBUST, BETTER PERFORMING FOR THE ENTIRE FLIGHTENVELOPE.