摘要
Purpose-Thruster point assembly mechanism(TPAM)of the electric propulsion system allows to adjust the thrust vector,sothat the thrust vectorisdirectedtothesatellitecenterof gravity(COG)during the satellite on-orbit working period.In this way the impact of disturbance torque caused by deviation of the thrust vector from the satellite COG during thruster ignition can be decreased.Therefore,the control accuracy of satellite is influenced directly by the control accuracy of TPAM.On the other hand,the on-orbit application of TPAM is restricted to the on-orbit computer resource.Therefore,the purpose of this paper is to design a control strategy for TPAM,and the strategy should not only be able to control the TPAM precisely but also be easily implemented by the on-board computer.Design/methodology/approach-First,the structure and work principle of TPAM are discussed,and the mathematical model based on D-H coordinate system is built for it.Then the fitting methods are utilized to design the control strategy of TPAM.Absolute position fitting-based control strategy and relative position fitting-based control strategy are designed,and the least squares algorithm is introduced for parameter selection.Findings-Simulations and tests are provided for the TPAM.Compared with the state-of-the-art PD controller,the proposed control strategy shows smaller overshoot and more simple realization.The experiment results are matched with the simulation results and both the experiment and simulation results show the validity of the proposed control strategies.Practical implications-The designed control strategies can be used for the TPAM of some satellite’s electric propulsion system.Originality/value-The mathematical model of the TPAM based on D-H coordinate system is given.The absolute position fitting-based control strategy and relative position fitting-based control strategy are proposed.Compared with existing methods,the two control strategies have more simple structure and smaller amount of computations.Furthermore,the relative position fitting-based control strategy achieves high precision with simple structure.
