| Due to the limited load capacity of spacecraft and the great complexity of the space environment,it is very easy for the spacecraft to lose their original functions because of exhaustion of fuel or some other faults,which will lead to the failure of space missionsThis paper mainly studies the optimal guidance and control of spacecraft and the attitude control method of underactuated spacecraft.The main innovations and contributions are as followsFirstly,for the optimal guidance and control of spacecraft,an optimal guidance method which can satisfy the six terminal constraints of velocity and position is proposed.Aiming at the spacecraft with controllable thrust direction,we establish the motion dynamics model of the spacecraft and then the corresponding optimal control problem.We transform the optimal guidance problem into the optimal control two-point boundary value solvability problem,which is solving the forward backward differential equation(FBDEs).Then we reduce the dimension of the FBDEs and the number of unknowns.For the problem that the classical New method is sensitive to the initial value,a hybrid algorithm based on Quantum particle swarm optimization and damping Newton method is selected to reduce the sensitivity of initial value for the algorithm.The feasibility of the algorithm is verified by simulationFor the attitude control problem of underactuated spacecraft,the spacecraft with only two fly wheels can not achieve three-axis attitude stability control when the total angular momentum of the system is not zero.In this paper,we proved that the spacecraft can achieve attitude stability along a certain inertial axis when the total angular momentum of the system is not zero.Tsiotras model is used to derive the target attitude of the spacecraft when the body angular velocity is zero.Then based on the linearized system state space model and the system’s characteristics of unknown model parameters but known structure,we get the approximate optimal LQR controller which is based on the data by the idea of optimal control theory and adaptive dynamic programming method.In the process of controller design,it can be completely independent of the mathe-matical model of the system.The numerical simulation shows the feasibility of the attitude stability scheme and the effectiveness of the control method. |
