基于滑模鲁棒算法的超低频主动隔振系统

摘要

An ultra-low frequency vibrational noise isolation apparatus from external vibration can be a critical factor in many fields such as precision measurement,high-technology manufacturing,scientific instruments,and gravitational wave detection. To increase the accuracies of these experiments, well performed vibration isolation technology is required. Until recently the cold atom gravimeter has played a crucial role in measuring the acceleration due to gravity and earth gravity gradient. The vibration isolation is one of the key techniques in the cold atom gravimeter. To reduce the vibrational noise caused by the reflecting mirror of Raman beams in the cold atom gravimeter, a compact active low-frequency vibration isolation system based on sliding-mode robust control is designed and demonstrated. The sliding-mode robust control active vibration isolation method is used to solve the vibration problem of Raman mirror in the cold atomic gravimeter. The purpose of vibration control is that the controller enables the system to be at zero state as the system states are away from the equilibrium due to vibration disturbance. In this system, the mechanical setup is based on a commercial passive isolation platform which only plays a role at higher frequency. A sliding-mode robust control subsystem is used to process and feed back the vibration measured by a seismometer which can measure the velocity of the ground vibration. A voice coil actuator is used to control and cancel the motion of a passive vibration isolation platform. The simulation and experiment results of vibration isolation platform show,on the one hand,that the vibration noise power spectral density decreases by up to 99.9%, and that the phase noise in cold atom interferometry produced by vibration decreases by up to nearly 85.3% compared with the results of the passive vibration isolation platform. On the other hand, compared with the lead-lag control method, the vibration noise power spectral density decreases by up to 83.3% and the phase noise in cold atom interferometry produced by vibration decreases by nearly 40.2%. Therefore,the sliding-mode robust control has the advantages of less tuning parameters,strong anti-interference ability,and more obvious vibration isolating effect.%振动噪声的有效隔离是冷原子重力仪的关键技术之一.为了减小冷原子重力仪中拉曼反射镜的振动噪声,研制了一套紧凑型低频主动隔振系统.其原理是利用滑模鲁棒控制系统处理和反馈由地震仪采集到的振动信号,利用音圈电机控制和消除被动隔振平台的运动.在0.1—10 Hz频域范围内,滑模鲁棒控制系统的残余振动噪声功率谱密度比被动隔振平台最大降低了99.9%,比超前滞后补偿控制方法最大降低了83.3%.滑模鲁棒控制算法还具有整定参数少、抗干扰能力强等特点.