Research on Integrated Control Method of Coaxial High-Speed Helicopter/Engine Based on Power Prediction Feedforward

To effectively meet the high-quality engine control requirements of coaxial high-speed helicopters with variable rotor speed, a novel integrated control method based on power prediction feedforward is proposed. Firstly, an integrated simulation platform of high-speed helicopter/engine is established to reveal the maneuvering characteristics of coaxial high-speed helicopter and the dynamic response of the variable-speed turboshaft engine under various flight conditions. It consists of a simplified coaxial high-speed helicopter model and a variable-speed turboshaft engine. Secondly, an optimal selection method based on random forest is employed to determine the optimal input variables for the demanded power prediction model, which is established through a mini-batch gradient descent neural network. Then, a high-order filter for gas turbine acceleration is designed to further suppress high-frequency interference without losing the low-frequency characteristics of gas turbine acceleration. Finally, the integrated control method based on double feedforward of demanded power prediction is proposed and validated through digital simulation under various typical flight conditions. The results demonstrate that the integrated control method based on double feedforward of demanded power prediction decreases the overshoot and sag of power turbine speed by more than 17.5% and 25.3% in multiple modes, which significantly enhances the dynamic quality of engine control system and enables the swift output of integrated coaxial high-speed helicopter/turboshaft engine system.