Methods for determining the mass of objects in motion using a one-component strain-gauge dynamometer

Increasing accuracy of weight-in-motion measurements is considered. Mass of moving objects is calculated through the measurement of unsteady force with the help of one-component strain-gauge dynamometers. It is shown that existing methods of dynamic weighing enable the measurement of non-stationary forces with an uncertainty exceeding 10 %. Such high error is related to the fact that, with higher speed, the accuracy of dynamic load measurements becomes more dependent on dynamical characteristics of the one-component strain-gauge dynamometer. New methods of dynamic load measurement eliminating the systematic error related to the dynamometer’s own dynamics have to be developed to increase mass determination accuracy. Two methods for weight-in-motion measurement of the mass of loads moving on the sensitive platform of a one-component strain-gauge dynamometer at high velocities are developed. Mass determination is carried out over a wide frequency range of the dynamometer, including the natural frequency. In order to apply the first method, only the dynamometer readings in the vicinity of the given point of time for calculating first and second time derivatives of the readings and the dynamical parameters of the dynamometer determined in laboratory conditions are required. To use the second method, it is necessary to first determine the natural frequency of the dynamometer with a platform, and then the frequency of the platform with the moving load. Then, measurement data obtained through methods one or two are used for calculating the mass. Average error in determining the mass using the first method was 2.8 %, and using the second method – 4.1 %. At the same time, the error did not exceed 6.0 %. The developed technology for determining the mass of moving objects can be implemented in weighing hardware for the use in many areas of industry, trade, agriculture and other.