Spacecraft Autonomous Rendezvous Maneuver And Attitude Tracking Control For On-orbit Servicing

With the rapid development of space technology, the structure and cost of spacecraft are more and more complex and expensive, respectively. In order to reduce the cost of on-orbit spacecraft and extend the servicing time, on-orbit rescue and repair for the target spacecraft have been obtained increasing focuses.During the on-orbit servicing implementation, the servicing spacecraft and target should achieve autonomous rendezvous and dock to each other, then on-orbit a series of operations will be performed. Hence, spacecraft autonomous rendezvous and docking(RVD) is one of the most significant techniques for on-orbit servicing. Spacecraft autonomous rendezvous and docking includes rendezvous role and docking role, which refers to orbital maneuver and attitude maneuver respectively. This thesis will make a detailed analysis and investigation for the multi-objective control problems of RVD, and present a series of systemic methodologies to solve these design problems in each stage of RVD.Considering the non-circle orbit for target spacecraft, we extend the classical Clohessey Wiltshire(C-W) equation to the case that the orbit of target spacecraft is non-circle,where the nonzero orbital eccentricity is described as the model uncertainty.During the stage that the Chaser moves from the initial position to the aimed position, a periodic data transmission mechanism from sensor to controller is presented.Considering saturation nonlinearity of actuator, limited-thrust and limited quadratic performance, an observer-based multiple-objective control law is presented to guarantee the task of orbit rendezvous to accomplish.During the relative position holding of Chaser and Target, the orbital maneuver is regarded as an output tracking control issue. A periodic data transmission mechanism from controller to actuator is presented, based on which a multiple-objective robust output tracking control problem with limited-thrust, limited quadratic performance and H∞ performance index is addressed. A linear matrix inequality approach is developed to make performance analysis for the orbit closed-loop control system in the relative position holding. Sufficient condition is established for the existence of the proposed state feedback control gain and it is shown that the proposed controller has disturbance-attenuation performance.For the determination problem of relative orbit in RVD, a sliding mode observer algorithm based on variable structure control theory is presented. There exists constraint that traditional robust H2 and H∞ filters can only handel bounded-energy disturbance and can only apply for exact system model, whereas sliding mode controller is completely robust to matched model uncertainty, nonlinearity and input disturbance. A new type of proportional and derivative sliding mode observer is developed, which can generate the exact estimation for both relative motion state and sensor fault.For attitude control systems during servicing spacecraft docking, an adaptive backstepping controller is designed to solve the high-precision attitude control problem. In the developed approach, by using adaptive mechanism, the upper bounds of external disturbance and actuator fault can be estimated. Based on the estimation information, the state-feedback controller is synthesized to stabilize the resulting fault system. Compared to sliding mode variable-structure controller, the proposed control scheme here can avoid the chattering phenomenon resulted from the switched term in sliding mode controller.