Study On The Influence Of End Load On Dynamic Characteristics Of Strain Gauge Force Sensor

Strain force sensors are widely applied due to their better static characteristics.But,their dynamic characteristics are poor due to their low natural frequency and small damping ratio;and,under working condition,the sensor tooling of support mechanism and end load will further reduce its dynamic characteristics,and thus increase its dynamic measurement error.Therefore,in order to evaluate the dynamic measurement performance of the strain force sensor in application or correct the dynamic measurement error,it is not only necessary to study the dynamic characteristics of the sensor itself,but also to study the influence of the tooling on the sensor dynamic characteristics.The dissertation thus mainly studies the influence of the end load on the dynamic characteristics of the sensor,and analyzes the variation rule of the sensor dynamic characteristic with the end load through simulation and experiment.In the simulation,first,the simplified model of "force sensor + end load" is built by cascaded mass-spring system,and its transfer function is derived;then,normalized structural characteristic parameters are introduced to characterize the end load,normalized dynamic characteristic parameters are introduced to characterize the dynamic characteristic of the sensor with end load,and accordingly numerical simulation of the sensor dynamic characteristic varying with the end load are conducted by MATLAB.By fixing the structure parameters of the sensor and changing that of the end load,the variation rule of the normalized dynamic characteristic parameters of the sensor is analyzed;by simultaneously changing the structure parameters of the sensor,the consistency of variation rule of the sensor normalized dynamic characteristic parameters is analyzed based on the coefficient of variation.The simulation results show that,the normalized dynamic characteristic parameters of the force sensor all change with the normalized mass,stiffness and damping of the end load regularly;and that,the variation of the normalized dynamic characteristic parameters with the end load is hardly affected by the mass and stiffness of the sensor itself,but only affected by the sensor damping ratio.Based on the simulation data,BP neural network is used to establish the model of the sensor normalized dynamic characteristic parameters varying with the sensor damping ratio and the end load structure parameters.In the experimental research,a strain multi-axis force sensor ATI-mini45 is taken as an example,dynamic calibration experiments for the sensor with mass-variable end load are conducted,and the dynamic response data of the sensor under different end load is obtained.Aiming at the multi-modal and dense modal of the sensor dynamic response,the piecewise integral iteration method is adopted,to obtain the modal parameters of the sensor under different end load weight conditions;then,the variation rule of the modal parameters with the end load weight is compared with the simulation results and the established neural network model.The results show that the variation rule of the actual sensor dynamic characteristics is basically consistent with the simulation results;whereas,because the parameters of the sensor itself and the end load itself are unknown,the quantitative difference between the experimental results and the simulation modeling results is tentatively analyzed.In general,the research results reveal the common characteristics of the sensor dynamic characteristic parameters varying with the end load.