Research On The Absolute Dynamic Torque Calibration Method Based On Inertia Acceleration

Torque is a key index for evaluating the dynamic performance of transmission components in the transmission system.By measuring the torque of each rotating component,it is helpful to scientifically evaluate the transmission efficiency of the entire power mechanical transmission system.In industry,torque measurement is generally carried out by means of torque sensors.Torque sensors are widely used in the detection of output torque and power of rotating power equipment such as motors,generators,and internal combustion engines,as well as in production monitoring and quality control.To ensure the accuracy and reliability of torque measurement,the torque sensor needs to be calibrated regularly.At present,the status quo of absolute torque calibration is mostly static calibration in the laboratory,and the method of cantilever beam plus weight is mainly used for calibration in the measurement laboratory.In terms of dynamic torque calibration,there are problems such as insufficient calibration range,imperfect calibration methods and lack of standards,which cannot meet the current and future measurement needs in various fields.Therefore,it is of great theoretical and practical significance to carry out research on dynamic torque calibration technology.The purpose of this paper is to study the dynamic torque calibration system and its key technical issues,and establish an absolute large-range dynamic torque calibration system to realize the absolute dynamic calibration of the large-range dynamic torque sensor.The specific research contents are as follows:Since the absolute dynamic torque calibration system is mainly realized based on the inertia acceleration method,this paper firstly conducts a detailed theoretical derivation and in-depth analysis of the inertia acceleration method principle.This paper starts with a single-degree-of-freedom undamped free torsional pendulum system,and analyzes the ideal dynamic characteristics of torque during torsional pendulum motion;then gradually increases the system conditions,and analyzes the dynamic characteristics of torque in damped system,sinusoidal excitation system,and multi-degree-of-freedom system,respectively.And compared with the ideal situation,the corresponding theoretical error is analyzed.Through the analysis of the single-degree-of-freedom sinusoidal excitation damping system,the relationship between inertia torque and damping torque for absolute dynamic calibration is given,which provides theoretical support for the subsequent design of the motor sinusoidal excitation absolute dynamic torque calibration system.Through the application of the transfer matrix method in the multi-degree-of-freedom system,the error formulas of the torque sensor to be calibrated and the circular grating at different positions of the shaft system are deduced,and three torque sensors to be calibrated,the circular grating and the standard inertia module in the system are given.The optimal shafting distribution structure of the main components provides a theoretical basis for the subsequent dynamic standard torque error analysis.In order to improve the measurement accuracy of angular acceleration in the dynamic torque calibration system,aiming at the problem of the pendulum center offset in the dynamic torque calibration system,a time-domain progressive sine fitting angle measurement error compensation method is proposed by analyzing the eccentricity error and inclination angle error caused by the eccentricity and inclination of the shafting during the measurement of the swing angular displacement.The pendulum center offset parameters of the shafting are obtained using the method,and the angular acceleration error,gravitational torque error and moment of inertia error when the pendulum center offset exists in the shafting are analyzed respectively,so as to obtain the optimal position of the swing center,so that these errors can be obtained.The impact on torque calibration is minimized.The experimental results show that the method can effectively compensate the angle measurement error and provide high-precision angular displacement measurement data for the subsequent measurement of the angular acceleration and the moment of inertia.In order to improve the measurement accuracy of shafting moment of inertia and the calibration accuracy of dynamic torque in the dynamic torque calibration system,this paper proposes the measurement method of moment of inertia based on modal decomposition and the calibration method of dynamic torque respectively.Firstly,the traceable solution model of the moment of inertia of the free t orsion pendulum damping system is derived;Then the application of EMD and VMD in the free torsion pendulum system is discussed.A free torsion pendulum moment of inertia measurement method based on E-VMD is proposed,and the effectiveness of the method is verified by experiments.The experimental results show that this method can effectively improve the accuracy of moment of inertia measurement.By discussing the application of EMD and VMD in motor sinusoidal excitation system,a dynamic torque calibration method based on E-VMD is proposed to improve the accuracy of dynamic torque calibration.A set of absolute dynamic torque calibration system(referred to as ME-DTC system)is built based on the inertia acceleration method in order to realize the dynamic loading and calibration of large-scale sinusoidal torque.The torque loading of this system is realized by controlling the dynamic output sinusoidal torque of the excitation motor,which can complete the sinusoidal dynamic torque calibration of multi-frequency and multi-range.Different from the vertical shafting structure in the existing research,this system adopts a horizontal shafting structure,which can improve the torque output efficiency of the excitation motor and help to achieve large-scale dynamic torque calibration.In this paper,a calibration experiment with an amplitude of 300 N·m and a frequency of 10 Hz is taken as an example,the specific steps and result analysis of the dynamic standard torque generation are given,and then the dynamic standard torque is used to calibrate the torque sensor and give Calibration error analysis,and finally gives the dynamic standard torque uncertainty analysis of ME-DTC system at different frequencies and different amplitudes.The experimental results show that the relative uncertainty of the amplitude expansion of the traceable sinusoidal dynamic standard torque generated by the ME-DTC system is less than 0.5%(k=2),which can meet the absolute dynamic torque calibration requirements of the large-range torque sensor,and solve the problem.The problem of insufficient calibration range of the existing absolute dynamic torque calibration method.