Research On The Static Test Error Of Four-point Piezoelectric Dynamometer

Due to the excellent test performance,piezoelectric dynamometers are widely used in thefield of precision testing of force loads.With the improvement of the requirements of the vector force measurement accuracy and the continuous development of the test and automatic control technology,higher requirements have been put forward for the test accuracy of the piezoelectric dynamometer.However,the measurement error of the piezoelectric dynamometer varies with the position of the loading point,and excessive errors even occur on some loading points.Therefore,it is of great significance to study error of piezoelectric dynamometer and obtain methods for improving accuracy.In this paper,the four-point piezoelectric dynamometer is taken as the research object.Based on the analysis of the testing principle,structural characteristics and force analysis of the dynamometer,the main error sources of the dynamometer are summarized.The main errors of the dynamometer are analyzed in detail.Through calibration experiments,the static performance indicators of the force measuring units and the dynamometer are obtained.From the dimension parameters,installation angle,sensitivity,fulcrum force and other aspects,the differences between the four points of the dynamometer are studied,and the sensitivity stability and its variation rule in the test are analyzed.The influence of calibration algorithm and assembly error on the test are analyzed,and the error transfer function is established.The method to improve the measuring accuracy of the dynamometer is studied.The mechanical model of the dynamometer is improved,the output model of the dynamometer in the area is established,and the maximum change signal function is proposed as the optimization target.Through selection,optimization of arrangement order and error distribution,etc.,the influence of differences among four pivot on the output of dynamometer is reduced.Simultaneous legislation and amendments are proposed to more accurately calibrate the sensitivity of dynamometer.The calibration of the dynamometer is performed in the area,and the results show that in the calibration of Z direction,the test errors of the joint legislation and the revised method are reduced by 71.5% and 56.5% respectively compared to the holistic method;in the calibration of X direction,the test error of the correction method is relatively reduced by 36.3% compared to holistic method.