| Passive electric-hydraulic servo system is also known as Electro-hydraulic load simulator or Electro-hydraulic load simulation turntable. It’s a Hardware-in-the-loop simulation equipment which can simulate loads of bearing system and do performance test to ensure the performance under laboratory conditions. It overcomes the defect of the physical field test, what’s more, it has good controllability and low destructibility, and can do many tests which will be convenient for recording and analysis data. Passive electro-hydraulic system is composed of two parts: loading module and loaded module(bearing module). The two parts are connected via a rigid shaft, and the force signals and angular displacement signals is respectively applied to the loading and bearing module, at the same time, the system achieves the closed loop control by using its own sensor of each module. Passive electro-hydraulic servo system has force/position coupling features, which reduce the rapidity and accuracy of the system. With load simulation towards high frequency and high precision, how to eliminate the surplus torque disturbance and improve the performance of simulator becomes a critical issue and catch the attention of researchers at home and abroad.In this paper, traditional methods of disturbance compensation which based on the angle of distance compensation is broken. Surplus force of system is regarded as the force/position coupling of loading module and loaded module, by the angle of decoupling, a synchronous structure decoupling method is come up which adopts duplex servo motor and stems from structure decoupling. Passive electro-hydraulic servo system is considered as a single input double output servo system, mathematical model of loading module and bearing module is established, the principle of force/position coupling is analyzed. On the strength of the system’s performance requirements, the structure of duplex servo motor is designed and optimized. Duplex servo motor has a double entry structure, consists of two motors, the motor of two nested within each other, so the duplex motor has a poor sealing condition. Take advantage of the finite element analysis software, the sealing property is analyzed, and the suitable seal form and its pre-compression is chosen. The model of passive electro-hydraulic servo system is built and its control performance is analyzed by using simulation software, then the model of passive electro-hydraulic servo system which adopts duplex servo motor is also built and its control performance is analyzed. By comparison, the new method of synchronous structure decoupling method which adopts duplex servo motor is confirmed to be effective. Then experiment platform of system is set up, experimental studies of new method’s effectiveness is done. The decoupling degree depends on the synchronization accuracy of duplex servo motor’s synchronous motor and bearing motor. With the aid of experimental platform, study of surplus torque experiment of two motors under synchronous state is done. The experimental results provide experimental support for synchronous control which used in synchronous structure decoupling method that adopts duplex servo motor as loading device. |
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