Space High Quality Microgravity Active Vibration Isolation Control

A well-designed space microgravity environment is an important guarantee of microgravity science experiments. However, the actual microgravity acceleration level of space station is far from ideal due to various disturbances. For this reason, the active vibration isolation technology of the microgravity has been firstly researched, verified and applied on the space shuttle and space station by the developed countries such as the U.S. and Canada.Along with the progress of Chinese manned space project step by step, there will be a lot of space microgravity science projects researched experimentally in the station in the near future. To provide the ideal space microgravity environment for the space science experiments, the space microgravity active vibration isolation system and the matched controller based on PID control technique is designed by Center for Space Science and Applied Research, Chinese academy of sciences. However, the active vibration isolation system based on the application of model compensation and PID technology is difficult to achieve ideal performance of vibration isolation because of its obvious coupling, nonlinearity, and uncertainties.Focusing on this problem, the physical structure, dynamic model and control objectives of the microgravity active vibration isolation system are discussed firstly in this dissertation. The contradiction between the dual targets of position and vibration isolation is discussed subsequently. In the meanwhile, the nonlinearity and multivariable coupling property of the controlled objects is concluded.Secondly, in accordance with the requirement for position starting and locking of the system, the displacement controller based on ADRC (Active Disturbance Rejection Control) technique were designed successively. And then, the vibration isolation controller is designed by combining the microgravity control loop with the displacement loop. As a result, the vibration isolation ability of the control system is improved significantly. And furthermore, the contradiction between the dual targets of the system is alleviated by means of cooperation of two loops and transition of the microgravity control loop. Thereby, the optimization of control performance is ensured. After that, According to different requirements in different work stages of the vibration isolation system, the comprehensive control scheme based ADRC was proposed.At last, the proposed ADRC scheme is compared with the existing PID scheme. The numerical simulations in the presence of system uncertainties and disturbances demonstrate the remarkable superiority of the proposed controller in terms of the position accuracy, rapidity, robustness, as well as the vibration isolation ability.