| Focusing on the rendezvous of libration point orbit,considering many constraints,character of uncertainty,the multi-constraint robust autonomous trajectory planning and control method for the rendezvous of libration point orbits are studied by using symplectic algorithm,hybrid series,Lyapunov-Floquet theory,character vector space,differential method and prescribed performance control theory and method.The main research work includes:(1)The fast calculation of invariant manifolds.In the process of designing lowenergy orbits,energy matching with the invariant manifold of the libration point orbit is required in real time.In order to solve the energy dissipation and low calculation efficiency of traditional numerical integration methods,a new method is proposed.The simulation represent that the proposed method with high accuracy,small energy error and high calculation efficiency compared with the traditional methods.(2)Based on the inverse dynamics method and invariant manifold connected is studied,we studied the low-energy and low-thrust transfer orbit of Earth-moon L2 libraton point orbit.The dynamic model of CRTBP in the geocentric polar coordinate system is derived,the optimization conditions of the transfer orbit are established,and an inverse dynamics method based on the mixed series is proposed.The Gaussian pseudospectral optimization method is used to realize the optimal design of low-thrust transfer orbit for the Earth-Moon restricted three-body problem system.The effectiveness and fastness of this orbital design method in deep space small thrust and low energy orbit optimization design are verified by simulation,which provides new design ideas and approaches for deep space mission spacecraft on-orbit and fast orbit design.(3)Research on the optimal control method based on Lyapunov-Floquet theorem.Aiming at the stable problem of the libration point,a libration point orbit stationkeeping control method is proposed.This method uses the transfer matrix of the timevariant dynamic equation.The Lyapunov-Floquet theorem is used to transform the timevariant motion equation into a time-invariant system containing the original equation state transition matrix.Using the two-point boundary value problem to solve the Floquet multiplier in order to reduce the amount of calculation.Finally,the LQR optimal control method is used to solve the problem.The optimal control realizes the station-keeping,which ensures the accuracy and the robustness of the tracking spacecraft.(3)Research on the control method of character vector space of the orbital intersection of libration point.In view of the uncertain factors in the process of the non-cooperative target rendezvous at the libration point orbit,the real trajectory deviates from the designed nominal trajectory,and the high-precision rendezvous cannot be achieved.A control method based on character vector space is proposed.The relative motion equation is linearized along the nominal trajectory,the eigenvalues and eigenvectors of its Jacobian matrix are obtained;Using the eigenvalues and eigenvectors to design the character vector space controller,and using the generic algorthim to optimize the controller parameters avoiding repeatedly adjust the parameters.The simulation representd that a high-precision autonomous rendezvous trajectory with disturbance of the libration point achieved.(4)In this paper,the libration point rendezvous and docking with a non-cooperative target is investigated based on the high-order integration-chain differentiator and prescribed performance control theory.Just knowing the relative position states,we propose a control law for spacecraft rendezvous during the terminal phase.Firstly,the differentiator is used to estimate the relative velocity states of the two spacecraft,and a mode-free prescribed performance controller is designed,which makes relative motion states of the two spacecraft asymptotically converge to the desired state within the prescribed boundaries.Then the Lyapunov function is used to prove the stability of the system when there are disturbances in the relative motion states.This method is closed-loop control and is independent of the model parameters.Thus it is easy to be employed online.Simulation results show that even though there exist uncertainties such as unknown disturbances and navigation and guidance errors,the proposed control law can achieve high-precision,real-time control of the spacecraft when tracking the non-cooperative target,and shows strong robustness. |
