Optimal low-thrust trajectory design and robust tracking control for spacecraft rendezvous

In this work, a low-thrust, fixed time, fuel-optimal constrained terminal approach direction rendezvous strategy is presented for spacecraft near elliptic orbit accounting for nonlinear differential gravity. There are two aspects in the approach presented: generating a optimal trajectory and tracing that trajectory. The optimal low-thrust trajectory obtaining minimum energy and given terminal approach direction is generated on-line according to the Geometric Hermite Interpolation. A feedback tracking control law based on robust control technique is employed to track the normal trajectory. The numerical simulation demonstrated that the current control strategy, with appropriate choice of parameters, can reduce fuel consumption effectively in the presence of bounded disturbances, and easy to implement.