Air-Breathing Combined Power Flight Vehicle Trajectory Optimization Method Based on the Aerodynamic Surrogate Model

The aerodynamic characteristics of air-breathing combined power flight vehicle change drastically with flight conditions during wide envelope. Using traditional trajectory optimization methods based on aerodynamic linear interpolation model, results show that the control variables and state variables change greatly with poor smoothness, which cannot meet working conditions of air-breathing dynamic model and make it difficult for control system design. In this paper, based on Hp adaptive pseudospectral method, the response surface surrogate model is put forward to gain smooth aerodynamic data, solving problems in the aerodynamic linear interpolation model. Results of ascent trajectory optimization of the Rocket-Based Combined Cycle power flight vehicle show that the angle of attack control changes smoothly and has small absolute value of the first derivative during the flight, and trajectory is relatively smooth, which provides ideal working condition for engine. Meanwhile, trajectory simulation using obtained optimal control variable is achieved, which shows small difference and further verifies the feasibility of the aerodynamic surrogate model.