Re-entry Trajectory Planning And Tracking Control Based On Height-velocity Profile

The lifting re-entry vehicle is gradually becoming a hot research topic in aerospace filed in recent years of its advantages of fast speed,long range and strong manoeuvrability.The development of this technology will have deeply impact on the future military developing strategy and defence system construction.In the re-entry process,the re-entry vehicle constrained by heat flow,dynamic pressure and overload,the design of re-entry trajectory and the design of the trajectory tracking control law are the key to the successful completion of the re-entry mission.Re-entry reference trajectory planning and tracking control law is studied for the Common Aero Vehicle(CAV)in this work,the main contents of this paper are including:1)In the aspect of re-entry trajectory planning,proposing a method of directly planning the re-entry reference trajectory in height-velocity profile.The path constraints will be transformed to the lower boundary in height-velocity profile by setting angle of attack profile and the maximum allowed path constraints values in advance,and the re-entry reference trajectory can be obtained by searching the increment of the lower boundary.The path constraints are satisfied because the increment is bigger than zero,and the terminal constraints can be satisfied by adjusting the magnitude of the increment.2)Proposing a trajectory design method can be satisfied additional geography constraints based on the improved artificial potential filed method.Assuming that the re-entry vehicle existing a potential filed during the re-entry process,the target and way point generates attraction force,no-fly zone generates repulsion force,the magnitude and direction of resultant force in potential field can be calculated,the heading angle corridor can be obtained by the direction of resultant force,the additional geography constraints can be satisfied by combine the heading angle corridor and bank angle reversal logic.Because of the heading angle corridor is determined by the direction of resultant force rather than the magnitude,therefore there is only need to confirm the relative relationship of attraction coefficient and repulsive coefficient,the algorithm of satisfied additional geography constraints is transformed to single parameter solving problem by pre-setting attraction coefficient or resultant coefficient,effectively simplify the solving method,and prompt the calculate efficiency.3)Using active disturbance rejection method design the trajectory tracking control law.On the previous condition that the velocity is the independent variable,the purpose of tracking the longitudinal trajectory can be realized by tracking altitude or flight path angle.Using the active disturbance rejection method design altitude tracking control law,the purpose of trajectory tracking is realized by compensating the disturbance observed by extended state observer.And combine the online trajectory design method which is using the latest generated trajectory as the nominal trajectory eliminate the accumulated error of last period,it can efficiently prompt the accuracy of the re-entry guidance algorithm.The results of the Monte Carlo simulation show that the above algorithm can effectively complete the re-entry guidance mission.