A linear parameter varying control methodology for reduction of helicopter higher harmonic vibration

Abstract

Vibration in helicopters can have a significant impact on their utility, maintenance, weight, performance, and cost of operation. This thesis focuses on the design of a vibration reduction controller that is effective throughout the flight envelope of the helicopter, in spite of variations in vibration levels and dynamics with flight condition. Analysis of a UH-60 Black Hawk helicopter modeled in the Rotorcraft Comprehensive Analysis System (RCAS) aeromechanical simulation environment indicates that the steady state vibration levels and the helicopter dynamics depend primarily on the advance ratio. Two baseline vibration controllers are developed, specifically the Continuous Time Higher Harmonic Controller (CTHHC) and an H[subscript of infinity] based controller, over a range of advance ratios. The unique controller developed in this thesis uses the Linear Parameter Varying (LPV) synthesis method, which provides performance and stability guarantees over the advance ratio parameter space. The three controllers are evaluated in the RCAS environment at fixed and maneuvering flight conditions. The results indicate that the full envelope controller designed using the LPV method exhibits increased performance over the CTHHC and H[subscript of infinity] controllers.