| Gravitational wave is a new way and means for human beings to explore and understand the universe.It is also an effective verification of Einstein's general relativity.Space gravitational wave detection is a hot topic in recent years,which is mainly based on the principle of laser interference.Laser light is emitted from a spacecraft,and then returns after being reflected by the surface of the test mass(TM)on another spacecraft.The returned signal interferes with the local signal,and the phase measurement of the interference signal is completed by the measurement system.Then the existence of gravitational waves is detected.As the reference datum of the laser interferometry system,the inertial sensor is one of the most important parts of space gravitational wave detection device.One of its main functions is to use the cage and vent mechanism(CVM)to ensure that the TM is safely and reliably fixed in the electrode housing during the launch phase.After the satellite enters orbit,the TM is released into space with high positioning accuracy and extremely low residual velocity.It can be captured by the electrostatic control system.This paper mainly focuses on how to control the CVM to realize the precise position and velocity control of the TM.1.In this paper,in order to control the hysteresis system of piezoelectric actuator unit in the CVM,the hysteresis was analyzed and modeled;NEXLINE piezoelectric linear motor was selected as the research object in this paper.The control system of the piezoelectric linear motor was composed of closed loop control based on fuzzy adaptive PID control algorithm and feed compensation based on polynomial fitting hysteresis model.The piezoelectric actuator was driven by DC voltage amplification circuit,and the grating ruler inside the motor was used as the feedback element.Based on FPGA and DSP,the whole closed-loop system was built and tested.The results prove that the controller designed in this paper can self-adjust the parameters to make the output displacement of the piezoelectric linear motor meet the expected goal when the initial parameters of PID controller are 0.2.Based on the adhesion force model,the relationship between the residual speed of the TM and the parameters of the CVM was derived,and a model of the CVM was established.An improved cuckoo search algorithm was proposed in this paper to identify the model.The simulation results show that the improved algorithm can improve the accuracy and success rate of identification.The success rate is increased from 86 % to nearly 100 % in the simulation experiment.The relationship between the parameters of the CVM and residual velocity is obtained by using the derived residual velocity of TM,which can establish the evaluation system of residual velocity on system parameters.3.A high precision force and displacement measurement system is designed to ensure the status of the TM.The displacement sensor of the CVM was designed by using resistance strain gauge and bridge circuit,and the calibration experiment was carried out to prove the performance of the displacement sensor.The designed displacement sensor has a nonlinearity of ± 0.4228 % and a precision of ± 0.8832 %,which basically meets the high precision requirements of the cage and vent mechanism for displacement. |
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