Abstract:

Two closed-loop near optimal guidance schemes, which are based on sampled-data optimal feedback control and pseudospectral trajectory reconfiguration, are studied and proposed for long-range rendezvous with finite thrust. They are defined respectively as the fixed sampling period(FSP) feedback and adaptive sampling period(ASP) feedback schemes according to different sampling period. Firstly, the dynamics model and fuel-optimal guidance problem are described. Combining the characteristics of the dynamics model with the pseudospectral method, a computational efficiency refinement method with the reduced state parameters, is proposed to improve the efficiency of trajectory optimization. Starting from the sampled-data optimal feedback control theory, the control command for closed-loop guidance can be updated and fed back continuously through successive trajectory reconfiguration using sampled data. The Simulation results indicate that the algorithms can not only supply excellent near optimal solution for practical mission, but can manage numerical errors, disturbances, and the J2 perturbation. Furthermore, the adaptive sampling period guidance scheme is not only more autonomous, but it has a better convergence for guidance accuracy with higher computation and fuel expense. Consequently, a favorable decision should be made for two schemes in application.