Direct Thrust Predictive Control of Air-Driven Ducted Fan Based on Composite Nonlinear Prediction Model

The air-driven ducted fan propulsion system has superior vertical takeoff and landing performance. Direct thrust control can further improve the effectiveness of thrust control. A direct thrust prediction control based on model predictive control (MPC) study was conducted for the air driven ducted fan propulsion system . In order to improve Prediction accuracy and ensure real-time performance, Designed a composite nonlinear prediction model (CNPM). CNPM consists of a tracking differentiator (TD), a state variable model (SVM) for driving engine, and a nonlinear mechanism model (NMM) of ducted fan. The tracking differentiator can arrange transition segments for input instructions, improve the dynamic performance of the system, and reduce overshoot. The large-scale state variable model can predict engine state changes based on future inputs, while the nonlinear mechanism model can estimate thrust in real-time based on the predicted and actual engine states. CNPM has high accuracy and real-time performance. A direct thrust control algorithm based on CNPM design model prediction. The simulation results show that the this algorithm reduces thrust overshoot by 30% and shortens the adjustment time from 20s to 5s compared to traditional linearized models. The proposed method can improve the control effect of thrust while ensuring real-time performance.