Research On Guidance And Control For Space Interceptor

Space interception is an important style of the space operation in future. The design of the system composed of intercept orbit, terminal guidance and attitude control is an important aspect of space interceptor design, it is directly related to interception accuracy and target damaged efftects. Intercep-tor will be failure to hit target because of the orbit calculation errors in the process of orbit intercep-tion, so it is necessary to introduce the feekback control in terminal interception to compensate the orbit calculation errors, that is terminal homing guidance law. In addition, attitude control should be executed to guarantee thrust direction of the orbit control engines to accurate orientation.This paper focus on the design of terminal guidance law, GPS-based attitude determination algo-rithm and attitude controller on the basis of presenting basic principle of interception orbit, moreover, numerical simulation is studied to test the above design.Firstly, the mathematical model of relative motion between space interceptor and target is set up, on this basis, variable structure guidance law and dynamic invers theory-based terminal guidance law are designed.Secondly, in attitude determination of interceptor, GPS-based autonomous attitude determination method is adopted and a new strategy is proposed in this paper, which aligns two groups of baselines on the interceptor. one group called short baselines resolves integer ambiguity since it's shorter than half of the carrier wave, the other group called long baselines determines Euler angle of space inter-ceptor more precisely.Thirdly, in attitude control of interceptor, attitude motion equations are divided into kinemics equations and dynamics equations based on singular perturbation in order to reduce the system to simplify the controller design. The adaptive sliding mode variable structure control law is designed considering uncertainty of inertia moment of space interceptor and outer disturbance torque. The adaptive law on-line estimates parameters to attitude controller.Finally, in the numerical simulation, Pulse-Width Pulse-Frequency(PWPF) modulation is used to modulate the continuous terminal guidance and attitude control sigal into equivalent control signal considering the executing agency of terminal guidance and control system is pulse engines. The nu-merical simulation results show the effctiveness of terminal guidance law and attitude control system.The contributions of this paper are as follows:1. Short baselines which is shorter than half of the carrier wave combined with long baselines is proposed in GPS-based attitude determination algorithm. The contradiction between the integer ambiguity caused by long baselines and the lower measurement precision caused by short baselines is solved.2. The adaptive sliding mode variable structure control law is designed based on Lyapunov sta-bility theory, and solved the robust control problem under the condition of interceptor atti-tude motion uncertainties.3. Considering the continuity of the guidance law and attitude controller, the Pulse-Width Pulse-Frequency(PWPF) modulation is designed as a technical realization measure.