Approach Guidance for Rendezvous of Non-cooperative Targets Based on Onboard Trajectory Planning

An approach guidance method based on onboard trajectory planning is proposed for the rendezvous of non-cooperative targets with terminal position and velocity constraints. Firstly, a convex optimization problem for the rendezvous trajectory is established and discretized. To simplify the gravity model in the convex optimization, a reference gravity sequence is generated by solving a sequence convex optimization problem, and stored for onboard utilization. Then, according to the thrust characteristics of the spacecraft, a two-stage guidance strategy based on trajectory planning is developed. In the first stage, the rendezvous trajectory is solved through a fuel consumption minimization problem with the terminal position and velocity constraints. In the second stage, the rendezvous trajectory is generated by minimizing the terminal position error and considering the terminal velocity as a constraint. The switching strategy of the two guidance stages is also given. Finally, the proposed approach guidance method is simulated for rendezvous missions of non-cooperative targets. The results show that the planning algorithm has good computational performance, and the guidance method is applicable to the rendezvous of maneuvering targets.