Attitude Takeover Control Of Serviced Spacecraft Based On Cellular Satellites

With the development of space technology,more and more attention has been paid to the advantages of cellular satellites with standardized interfaces compared with traditional satellites in on-orbit assembly technology,on-orbit maintenance and attitude taking over tasks.In this paper,the attitude takeover control problem based on cellular satellite is studied.The quantized attitude control scheme,the prescribed performance control scheme and the differential game-based distributed control scheme are designed respectively.Firstly,a quantized backstepping adaptive attitude control scheme is designed to solve the problems in the attitude takeover task,such as the limited communication between the computer cellular satellite and actuator cellular satellite,the unknown inertia of the combination body and the limited torque output capability of the actuator.Hysteresis quantizer is used to discretize the control commands of computer cellular satellite and therefore reduce the communication frequency and transmission volume.For the limitation of input saturation,the auxiliary system along with Nassbaum function is employed to expand the dimension of system and adaptively adjust the outer-level coefficients.In the meantime,an adaptive controller is designed based on the backstepping design idea,and the nonlinear dynamics and environmental disturbances including the unknown inertia matrix are estimated by the adaptive estimation law,and then eliminated by the robust control comprised of hyperbolic tangent function structure.Then,according to the requirements of steady state and transient state performance of attitude takeover control,a prescribed performance control scheme based on finite time extended state observer is designed.The restricted tracking error is mapped into free space and the corresponding transformation error dynamics is deduced.A finite time extended state observer is designed to estimate the attitude angular velocity information and the total disturbance-like term containing nonlinear internal disturbance and environmental disturbance torque in the transformation error dynamics.On this basis,a prescribed performance controller is designed with the transformed error as the feedback information to ensure that the attitude quaternion and attitude angular velocity tracking errors are always within the preset boundary.Finally,a distributed attitude takeover control scheme based on differential game is presented.The attitude takeover control problem is transformed into a differential game problem.With the help of reinforcement learning,the coupled HJB equation was solved by policy iteration,and the value function is approximated by the value function approximation method in the solution process,and the updating law of the weight vector was derived by the concurrent learning algorithm from the perspective of parameter identification.Finally,the optimal control strategy for each cellular satellite is obtained.In addition,the tracking differentiator technique is used to estimate angular acceleration information to eliminate the necessity of information exchange among cellular satellites.The numerical simulations of the above three control schemes are carried out,and the simulation results verify the effectiveness of the strategies.