Reserch On Development And Performance Analysis Of FAST New Hydraulic Actuator

The 500 m aperture spherical radio telescope(FAST)is one of the nine major scientific and technological infrastructures in China.Its new design ideas and natural geographical advantages make it the most powerful observation ability in the world.As the driving device to control the position and speed of cable net nodes of fast active reflector,the performance of electro-hydraulic actuator affects the observation accuracy of active reflector system.In this paper,aiming at the reliability and stability of the electro-hydraulic actuator in the original fast active reflector system,a new electro-hydraulic actuator applied to the fast active reflector regulating system is developed.In order to verify whether the new actuator meets the requirements of the position and speed control of the cable net nodes on the active reflector,the working condition,dynamic performance and control strategy of the new electro-hydraulic actuator are emphasized The new electro-hydraulic actuator system is simulated.First of all,in order to avoid the shortcomings of the original system,a new type of electro-hydraulic system with servo motor direct drive and closed pump control is designed,and the calculation and selection of relevant system components and the establishment of simulation model are carried out.Secondly,based on the non-linear characteristics of the asymmetric cylinder in the electro-hydraulic actuator,the accurate mathematical and simulation models of the servo motor,hydraulic cylinder and other key components of the fast new electro-hydraulic actuator system are established,and the simulation models of the permanent magnet synchronous servo motor and key hydraulic components are verified.In addition,this paper analyzes the load stability of pump controlled asymmetric cylinder,obtains the unstable working load area of the system,and puts forward the system scheme of using balance valve to improve the stability of the system in the unstable working area.The simulation results and theoretical analysis show that the system works stably when the working condition changes.Based on this,a multi-disciplinary EHA model composed of pump controlled differential cylinder system,motor system and controller is established.The adaptive robust controller is designed for the nonlinear state space equation of the pump controlled asymmetric cylinder system,which provides the guarantee and theoretical basis for the performance analysis of the new actuator system.Finally,the position tracking performance and speed tracking performance of the whole simulation model of the new electro-hydraulic actuator under the designed controller are simulated and analyzed.The results verify the correctness of the simulation model of the new electro-hydraulic actuator.The designed system has high position and speed tracking accuracy and meets the use requirements.