Research Of Multi Stage Vibration Isolation And Orientation Integrated Control Method For Satellite

With the development of aerospace missions,the optical payload demands higher attitude accuracy and stability of satellite.But the imaging quality of the optical payload is severely affected by both low and high frequency vibration produced by satellite components such as flexible appendages and attitude control actuators.To provide an ultraquiet environment for optical payload,this dissertation mainly studies vibration isolation of control moment gyro(CMG)and vibration and orientation integrated control of Stewart platform.At first,the geometry structure of CMGs in pyramid configuration is analyzed and a truss envelope structure is designed.To isolate the vibration caused by CMGs,a CMG vibration isolation unit is design and the dynamic model of the unit is built,by frequency domain analysis,the CMG vibration isolation unit shows a good three-axis decoupling characteristic and high frequency vibration attenuation characteristics.Then,the CMG vibration isolation unit is used on satellite and the dynamic model of the whole satellite is built.The numerical simulation shows that the CMG vibration isolation unit can improve the stability of satellite attitude more than an order of magnitude.In order to further improve the attenuation ability of the vibration caused by CMGs and effectively utilize the truss envelope structure,the truss structure is transformed.A part of struts in the truss structure is replaced by spring damping strut and active-passive integrated vibration isolation control strut based on the disturbance characteristics of pyramid-type CMGs,the dynamic model of vibration isolation truss structure is built.The dynamic characteristics of truss structure is analyzed,which shows the active vibration control can effectively reduce the harmonic peak at low frequency and does not affect its high frequency response characteristics.Then the whole satellite simulation with vibration isolation truss structure is carried out,the truss structure keeps stable and the shape variable is small in the whole simulation,and it satisfies the requirement of attitude control as well as improves the stability of satellite attitude.Secondly,vibration and orientation integrated control method of Stewart platform is studied and analyzed to improve the imaging quality of optical payload.Two kinds of orientation control method is proposed depending on the difference of measurement information,then,considering about optical payload rapid orientation after a large-angle attitude rapid maneuver with a satellite,the whole satellite attitude control loop is designed.Meanwhile,a calculation method of path planning function is proposed to solve the problem that satellite may show a bad controller reaction to large-angle attitude rapid maneuver.Next,the relationship between the stroke precision and the platform pointing precision,the limit of the platform's movement ability and the influence produced by measurement error on the control accuracy with different control methods are analyzed.Finally,the effectiveness of the whole satellite control loop is verified by numerical simulation without considering attitude control actuator.Then the CMGs with truss structure are used as actuator,the simulation results are compared and analyzed,which show that the pointing accuracy and stability of payload is greatly improve and a ultraquiet environment for optical payload is provided by using the vibration and orientation integrated control platform.