Research Of Staring Imaging Attitude Control

Staring imaging of spacecraft is a new method to observation, compared with traditional method of taking pictures, it can take video which can continuous record message of target and get important information of hot spot or disaster-affected area for people to make decision. The mission of staring imaging requires rapid and high precision attitude tracking which is focused on by the paper. The main work of this paper is listed as following.A model is established with the kinemics and dynamics equation of rigid spacecraft attitude tracking. First, the basic knowledge of quaternion is introduced, and the spacecraft attitude tracking kinemics equation which is described with quaternion is derived. Second, the spacecraft attitude tracking dynamics equation is derived by using rigid mechanics knowledge. Then the orbit information of spacecraft and the position information of target are used to compute the expected attitude angles and attitude angular velocity of spacecraft when it is staring imaging. Finally A torque configuration scheme is developed.A PID method is introduced to design the spacecraft attitude controller. First, the basic principle of PID is introduced and a simple PD controller is designed. There is a numerical simulation for it. Second, to solve robust and saturation problem, another two method, the fuzzy PD method and the robust adaptive method, are proposed. The numerical simulation shows that the method can take effect.To guarantee the spacecraft has a rapid attitude tracking ability. A finite time control method is proposed to guarantee the spacecraft attitude track the given desired attitude in a finite time. First, the basic principle of finite time control is introduced. Second, a terminal sliding mode control method and a homogeneous method of nonlinear system are introduced design the finite time spacecraft attitude controller. Finally, the numerical simulation results show that the two method both can achieve the attitude tracking control of staring imaging, guarantee the closed-loop system converge to a small region of equilibrum point in finite time and are robust against uncertainties and disturbances.To guarantee the spacecraft has a high precision attitude tracking ability. A sliding mode control method is proposed to guarantee the spacecraft attitude track the given desired attitude accurately with uncertainties and disturbances. First, the basic principle of sliding mode control is introduced. Second, a simple sliding mode controller is designed to control the system. To accomplish rapid and high precision attitude tracking simultaneously, a method of finite time adaptive integral sliding mode controller is proposed, the adaptive method is adapted to set the switching gain and estimate bound of the disturbances and parameter uncertainties. Theoretical analysis verifies that the method has the advantages of both the finite time method and the sliding mode method. It can make sure the closed-loop system converge to a small region of the equilibrum point in finite time and are robust against uncertainties and disturbances. Simulation results show the effectiveness and feasibility of the controller.Hardware-in-loop simulation of spacecraft attitude control based on single axis air-bearing platform is performed. First, a brief introduction of the simulation system is performed. Second, single axis air-bearing platform is used to simulate the pitch channel of spacecraft attitude motion, another two channels are simulated by numerical simulation. Finally, the system is carried out to verify the control method proposed, the hardware-in-loop simulation results show the effectiveness and feasibility of these controllers.The work of the paper is a positive help to the research of staring imaging spacecraft. It is also a useful reference to other attitude control problem.