Design and Optimization of Low Impact Shift Control Strategy for Aviation Transmission Power System Based on Response Surface Methodology

Abstract

The utilization of a variable-speed power system significantly improves the forward flight speed and cruising range of the helicopter. Nevertheless, the shock of speed and torque during the shift process brings stability and safety problems that cannot be ignored. Thus, swift and stable shift control is a key issue in the research on aviation power systems. This study focuses on the design and optimization of low-impact shift control strategies for a variable-speed power system, which involves multiple control variables, long adjustment times, and uncontrollable risks due to the nonsteady state. A comprehensive power system model that integrates the engine, a two-speed dual-clutch transmission system, and the main rotor was proposed. By selecting the engine fuel flow, friction clutch hydraulic pressure, and rotor pitch angle as input signals, regression fitting models between the input signals’ starting time points and speed or torque shock were obtained using Response Surface Methodology (RMS). The interaction effect of multiple time series was analyzed, and four kinds of low-impact nonlinear programming multi-objective optimized models for speed or torque are proposed. The results indicate that the P values of the RMS fitting models at upshift and downshift are less than 0.0001 and 0.05, respectively, which are highly significant and can effectively predict the shift dynamic response; under the optimized upshift and downshift control strategy, the speed and torque shock are reduced by 5–10%.

Keywords

• helicopter
• variable speed transmission
• gearshift strategy
• RMS