Trajectory Optimization of Continuous Descent Approach (CDA)by a Gauss Pseudospectral Method

Aiming at optimizing trajectory problems of linear continuous descent approach (CDA)of the aircrafts with a constant gliding angle,a Bolza optimal control problem (OCP)is converted into a nonlinear programming problem by the Gauss pseudospectral method under different flap states of aircrafts,resulting in an optimized time of CDA trajec-tories.A dynamic model of CDA is established,where state variables of flight position and control variables of trajectory angle are determined,and performance measure of minimizing landing time is proposed.B737-800 aircrafts are selected for a case study.GPOPS algorithm is used to optimize trajectory via the Gauss pseudospectral method,within the landing areas and flying areas and the position of top of descent (TOD)and the curve of speed control are determined.Compared with other algorithms for computing CDA trajectory,the Gauss pseudospectral method has several advantages.This stud-y analyzes the approaching state of 1 7 CDA trajectories and 1 traditional trajectory in landing areas.The results show that compared with traditional stepped approaching trajectory,the landing time of CDA trajectory computed by Gauss pseudospectral method decreases by 1 6.67%.Simulation results verified that the CDA trajectory optimized by Gauss pseudospectral method can reduce landing time and improve accuracy of track forecast and efficiency of flight control sys-tems.