Active Vibration Isolation Controller Design Based On Stewart Vibration Isolation Platform For Spacecraft

With the progress and development of science and technology,the requirements for performance and precision of the spacecraft is higher and higher.The previous rigid spacecraft have been unable to meet the needs of contemporary.Modern spacecraft have large flexible attachments such as antennas and solar cells.The movement of the flexible attachments produces low frequency micro-vibration which affect the performance and accuracy of high-precision instruments on the spacecraft.For the micro-vibration on spacecraft,the multi-degree of freedom isolation method is generally adopted.For low frequency vibration,active vibration isolation control is generally adopted.The Stewart isolation platform is adopted in this paper.Combined with active vibration isolation control method,the vibration isolation control of high-precision instruments on flexible spacecraft is carried out.This paper mainly studies the following aspects:The dynamic model of the platform obtained by Newton-Euler method is adopted.Voice coil motor is used as the actuator of vibration isolation platform.Based on the development of current technology,the working environment of the platform and the characteristics of the platform itself,two reasonable assumptions are made.The dynamic model of vibration isolation platform and the voltage balance equation of voice coil motor are simplified by assuming.It provides an effective mathematical model for controller design.In consideration of the ideal voice coil motor,that is no disturbance and uncertainty in the voltage balance equation.When the upper bound of platform interference exists,an active vibration isolation controller is designed for the known and unknown upper bound.Based on the strong robustness of sliding mode control to external disturbance and system uncertainty,a sliding mode active vibration isolation controller is designed.An adaptive sliding mode isolation controller is designed to estimate the upper bound of the disturbance.Finally,The control performance of the designed controller is verified by simulation.Uncertainty and interference terms are added to the voltage balance equation of voice coil motor.The simplified platform dynamic model and the voltage balance equation of voice coil motor are integrated into an augmented dynamic equation.When the upper bound of external disturbance is known,the backstepping sliding mode vibration isolation controller is designed by combining the backstepping method and sliding mode control.When the upper bound of external disturbance is unknown,an adaptive backstepping sliding mode vibration isolation controller is designed based on backstepping sliding mode vibration isolation controller with adaptive algorithm.Finally,the control performance of the two controller is verified by simulation.