Attitude Control Technology Of A Small Video Satellite

With the low-cost and agility of its attitude control system and the continuity of video observing technology, Small Video Satellite(SVS), as a new research field in recent years, could complete continuous observing mission towards the targets on the ground. Its main on-board mission in the normal mode is to observe the targets on the ground or in the space in a long time and continuously. In this paper, the attitude control technology was studied deeply and some useful concrete technology was developed according to the characteristics of the actuators. The main work of this paper is listed as the following.The tracking error was analyzed from the kinemics and dynamics function. The sources of SVS tracking error were analyzed from the dynamics equations and kenimatics equations. Then the relationship between those sources and errors were analyzed and deduced.The compounded thrusters system & flywheels control strategy based on the double switching hyper-spheres was developed. According to the observing time-span of SVS, it request that the satellite can response the command of the desired attitude in a short time in the first tracking phase. Then the respective disadvantages of flywheels and thrusters applied on the satellite were analyzed by simulating results. To conquer these problems, the new control strategy, utilizing both flywheels and thrusters, named as"double switching hyper-spheres strategy"was proposed and analyzed detailedly.Then a single-axis simulation and three-axises simulation with this strategy were developed and their results demonstrated its fesibility and validity. The phase-plane time-optimal control and PWPF modulating theories were improved in order that those can be used in the inchoate tracking control of the video satellite. Base on the optimal control theory, the phase-plane time-optimal control law was employed to eliminate the initial bias of the attitude error with the small thrusters system. In order to enhance the agility of the small thrusters system, the PWPF modulating theories was also employed. The simulation results demonstrated the fesibility and validity of both theories.The sliding-mode control and nonlinear robust adaptive control theories were improved to be used in the stable tracking control of the video satellite. A"Feedforward Compenstaion & Error PD & Sliding Mode"control law was proposed to resolve the stable tracking control problem under the condition of inertial uncertainty and disturbance uncertainty. To prove its stability, the Lyapunov method and a simulation were both utilized. Another nonlinear robust adaptive control law was also developed, the Lypunove stability theory and Barbalat lemma were cited to prove its stability of the controller and the uniform boundedness of the estimated parameters. The simulation results show that this nonlinear robust adaptive control law could complete the high-precision tracking/staring mission.The physical simulation platform of satellite single-axis attitude control based on the single-axis air-bearing table was designed and the singal-axis physical attitude control simulation of vedio satellite was completed.A physical simulating & validating satellite singal-axis attitude control platform with singal-axis air bearing table was designed and constructed. With this platform, the SVS attitude control technology proposed in this paper was demonstrated.The work of this paper gives a reference scheme for the the development of SVS attitude control system, and shows the preferable application value for the satellites having the attitude tracking mission.