Research On Control Technology For Spacecraft Integrated Power/Attitude Control System

As a function integration solution for spacecraft, the integrated power/attitudecontrol system (IPACS) can meet the energy storage and attitude control requirementssimultaneously by controlling and steering energy storage device. It can not onlyovercome the shortcomings of chemical batteries, i.e., the shallow depth of discharge,the low specific energy, etc., but also reduce the overall weight and size of spacecraftand increase the payload capacity significantly. While the control technology of theintegrated energy storage and attitude plays a key role to the IPACS, several controlmethods are studied in this thesis in consideration of the engineering practical issue. Themain results of this dissertation are summarized as follows:The general nonlinear IPACS dynamics model for spacecraft is derived andthe spacecraft attitude tracking control law with asymptotic stabilization, whichcan help to implement the function of IPACS preliminarily, is proposed. In themodel the power/attitude flywheel is introduced as the actuator and the modifiedRodrigues parameters (MRPs) are chosen to describe the attitude kinematics of thespacecraft. Combining with the reference attitude of the spacecraft the attitude trackingequations are derived to design the control law.Considering penalties on both the attitude tracking error and the controleffort, an optimal nonlinear feedback control law with asymptotic stabilization isproposed for the IPACS. By the means of perturbation analysis and zero dynamics thegeneralized tracking error system is transformed into a feedback equivalentJurdjevic-Quinn (J-Q) type of system. Then utilizing the characteristic of the J-Q typeof system the specified Lyapunov function satisfying the asymptotic stability and theHamilton-Jacobi-Bellman equation simultaneously is successfully found, which leads tothe stabilized optimal nonlinear feedback control.An adaptive control law for IPACS is designed with actuator uncertainties.Both the attitude tracking error and the function of the IPACS can be greatly affected bythe uncertainty of the actuator. Utilizing the Lyapunov method a parameter adaptationlaw is derived. And by introducing the smooth projection algorithm, the effectiveness ofthe IPAC law is guaranteed, i.e., the singular situation of the adaptive law can beswimmingly avoided with the smooth projection algorithm.A simulation system for a satellite in a near-earth orbit is provided to test theproposed IPACS control laws. In order to validate the function of the IPACS, a seriesof task is designed, including tracking a target fixed on the earth, pointing to the sun,providing a long term power consuming and a random impulse power requirement, andthe battery charging task.