Study On Dynamic Calibration Method And Law Of Dynamic Characteristics Changing With Load For Multi-axis Force Sensor

In scientific experiment and industrial production,the requirement of dynamic measurement accuracy of multi-axis force sensor is getting higher and higher.Whereas,the dynamic characteristic of stain multi-axis force sensor is poorer and is affected by different working conditions,so,it is of great significance to study the dynamic characteristic of stain gauge multi-axis force sensor.Accordingly,the dissertation mainly studies the dynamic calibration method of the strain gauge multi-axis force sensor and the common law of the influence of the end load mass on the dynamic characteristic of the strain gauge force sensor,so as to provide reference basis for the sensor selection and tooling design under different working condition and provide an alternative method for dynamic calibration of multi-axis force sensor under working conditions.In the research of dynamic calibration method,the design criteria of full rank condition of different excitation signals'combination are firstly summarized for typical mixed excitations,based on which the mixed impulse and step excitation loads are to be applied to the sensor,then the input load identification method of mixed excitation is proposed to obtain the dynamic input of each channel of the sensor under mixed excitation condition,and last simulation and experiment of dynamic calibration of multi-axis force sensor by mixed excitations are carried out.Meanwhile,simulation and experiment of dynamic calibration of multi-axis force sensor by unit excitation are carried out for comparison between different dynamic calibration methods.According to the sensor dynamic calibration experimental data,identification method and frequency response calculation method,the frequency response curves of each channel of the sensor under different dynamic calibration methods are obtained,and the availability of the hybrid excitation method is demonstrated by comparing the experimental results of mixed excitation and unit excitation calibrations;at the same time,the frequency response curves derived from the unit step excitation method and the mixed step excitation method,as well as the mixed step excitation method and the mixed impact excitation method,respectively,are analyzed and compared,and the application suggestions of the different dynamic calibration methods are accordingly provided.In the study of the influence law of the end load mass on the dynamic characteristic of the sensor,the cascade model of the end load plus sensor and the normalization method are adopted for numerical simulation.The influence law of the normalized mass of the end load on the dynamic characteristic of the sensor and the lumped-parameter law model of the variation of the normalized natural frequency and the normalized resonance peak of the sensor with the normalized end load mass with sufficient stiffness is summarized.Then,based on ANSYS finite element simulation,the influence of the normalized mass of the end load on the normalized natural frequency of the sensor is studied.Thirdly,the dynamic calibration experiments of the variable end load mass are carried out on the direction of Fx and Fz of the sensor,and the effects of the normalized mass of the end load on the natural frequency and resonance peak values were analyzed.Finally,by comparing the simulation results of the lumped-parameter model,the ANSYS simulation results and the dynamic calibration results of the sensor with varied end load,the common influence law of the end load mass on the natural frequency of sensor is obtained:when the stiffness of end load is large enough,the sensor's normalized natural frequency decreases with the increasing of the normalized mass of the end load;the relation between the quantitative model of the variation of the actual sensor natural frequency with the end load mass and the lumped-parameter model can be fit by 1^st-order function,which reveals the quantitative common law of the sensor dynamic characteristic varying with its end load to a extent.Accordingly,it can provide a reference basis for the strain force sensor selection,tooling design,and dynamic estimation under different working conditions.