| With the development trend of large diameter and high resolution of space optical load,the suppression effect of space micro-vibration on its imaging quality is increasingly prominent.Therefore,a large number of ground tests are needed to test the imaging effect of space optical load in the micro-vibration environment.Vibration source is a recognized difficulty.After investigating and analyzing the characteristics of micro-vibration in space and a large number of test data of micro-vibration in orbit and on the ground,a simulator that can reproduce the characteristics of micro-vibration in space is proposed to be developed,which can be used as the source of micro-vibration in optical load ground test.Firstly,the mathematical model of the simulator is established by using the theory of dynamics,and the analytical expression of the natural frequency of the system is derived by using the principle of virtual work and the newton-euler equation.According to the in-orbit micro-vibration test data of the fifth aerospace research institute and Japan aerospace development group,the design index of the simulator is determined,and compared with similar equipment indicators at home and abroad,so that the design index is reasonable,feasible and advanced,and can cover the needs of in-orbit micro-vibration.According to the system model and design index,the optimal configuration parameters and the maximum axial stiffness of the simulator are solved while the axial stiffness is guaranteed.Secondly,according to the configuration optimization for the design of the parameters,the structure of micro vibration simulator was designed and the simulation analysis,based on the platform components,single axis actuator(include the design of the spring piece,the motor selection and the structure layout)of the actuator was optimized,make every parts can satisfy the design index,and the whole machine has carried on the finite element analysis,the simulation results show that the machine 6 order fundamental frequency of 3.4 Hz,the seventh fundamental frequency 356 Hz,meet the bandwidth requirements.The suspension system is designed according to the load carrying capacity in the design index,and the specific design is carried out to ensure the gravity unloading function,leveling function,frequency requirement and strength requirement of the suspension system.Then,for the research of the control strategy,the paper puts forward a kind of based on the transfer function of closed loop iterative control algorithm is verified,and the algorithm are verified by the simulation to the design of space micro vibration control precision maximum error is only 1.54% of the simulator,and solving the simulator in selected the ability to work under the driving force of voice coil motor satisfy the design index.The hardware equipment selection of the control system is completed to ensure that it can meet the control requirements of the micro-vibration simulator.In the Twincat software system developed by beifu company,the code of the control algorithm is written and the control interface is built based on PLC language,which can meet the control requirements of various working conditions during the micro-vibration test.Finally,the performance test of the single shaft exciter is carried out to ensure that it can cover the proposed design indexes and meet the requirements of the whole machine assembly.For the frequency range of control error exceeding the allowable range,two methods are adopted to solve the problem.One is to carry out one or two iterations,and the method is proved to be effective at low frequency range.Second,in the case of high frequency band(255Hz,320Hz),it is still unable to reduce the control error by multiple iterations.By taking into account the phase difference,the calibration matrix is re-determined,and the updated transfer function is used for control,the problem is solved and the error meets the requirements.The experimental results show that the designed space micro-vibration simulator satisfies the design criteria. |
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