Study On Rendezvous Trajectory Optimization And Guidance Method Based On Inverse Dynamics

When the engine thrust is low,the pulse assumption will produce a relatively large error,then study of low-thrust orbital maneuver problem is necessary and meaningful.However,continuous low-thrust orbital maneuver problem is quite complicated.The nonlinearity of the low-thrust trajectory model is very strong,and it is very difficult to find the trajectory in the form of analytic solution directly,which greatly increases the challenge of space missions.To obtain the optimal or suboptimal trajectory to meet the constraint conditions quickly or even in real time,this paper applies the inverse dynamics to study the continuous low-thrust spacecraft trajectory optimization and rendezvous guidance method based on high order polynomial.The main results of the paper are as follows.A rapid optimization model of low-thrust spacecraft rendezvous trajectory based on inverse dynamics is proposed,which realizes the fast off-line design of rendezvous trajectory at task design stage.1)By introducing the basic principle of hpadaptive Radau Pseudo-spectral Method briefly,the autonomous rendezvous trajectory optimization model based on hp-RPM is established.2)By introducing inverse dynamics,a rapid optimization of rendezvous trajectory based on high order polynomial is established.3)Taking the minimum fuel consumption as index,and taking the polynomial coefficient as optimization variables,then the Sequential Quadratic Programming algorithm is used to optimize the continuous low-thrust spacecraft rendezvous trajectory quickly.The simulation results show the proposed algorithm can greatly improve the computing speed under the premise that the fuel consumption is only a small increase compared with hp-RPM and the calculation accuracy is high enough.A closed-loop guidance method for nominal rendezvous based on inverse dynamics is proposed,and then a closed-loop guidance method for deviation rendezvous based on radar-based relative navigation filter is realized.1)The closedloop guidance method for low-thrust spacecraft rendezvous based on inverse dynamics is designed and verified by simulation.The results show that the method is very efficient,and the computational time is less than 1s.2)Considering the deviation factors in the actual rendezvous process,a relative navigation Extended Kalman Filter based on the rendezvous radar measurement is designed,and then a closed-loop guidance method for deviation rendezvous based on inverse dynamics is proposed.It can be seen from the simulation results that the method has high terminal control accuracy and relative navigation accuracy.3)The Monte Carlo process of the closed-loop guidance method for deviation rendezvous based on inverse dynamics is simply modeled.The simulation results show the method has high terminal control accuracy and navigation accuracy.The optimization of obstacle avoidance rendezvous trajectory based on inverse dynamics is studied,and an adaptive method for obstacle avoidance rendezvous trajectory optimization is proposed.1)An obstacle avoidance constraint model is established,which realized a rapid design of obstacle avoidance trajectory.If taking the convergence solution obtained without considering the collision constraints as the initial value of obstacle avoidance trajectory optimization,the feasible optimal rendezvous trajectory can be generated quickly.The speed of the algorithm is fast and the stability is high.2)The obstacle avoidance constraint model is improved,which realized the adaptive partition of the constraint discrete points,and then an adaptive model for optimization of obstacle avoidance rendezvous trajectory is established.3)The simulation results show,the algorithm can improve the trajectory of the collision avoidance constraint,and the computational efficiency of the algorithm is improved compared with that of the unmodified one.When comparing with the case of a single obstacle,the computational time increases due to the increment of number of valid constraints needed to be dealt with in the case of multiple obstacles.With the development of electronic propulsion technology,low thrust orbits could be widely used in the future space missions.In this dissertation,from the view of space missions,the method of trajectory fast-design and real-time guidance for rendezvous based on inverse dynamics using continuous low thrust are studied,conclusions of this dissertation may have some reference value.