Determination of Parameters of Second Order Integration Model for Weighing Scales

Abstract

Abstract. Paper presents physical background of the second order integration model for laboratory weighing scales. Moreover, method of identification of the model's parameters is described. This method enables determination of parameters for both static and dynamic characteristics of the object. On the base of the determined model, the weighing scale control algorithm may be optimised. As a result, due to this optimisation, the weighing process may be significantly shortened, what is especially important from the point of view of the laboratory equipment's functional parameters. IntroductionLaboratory weighing scales operate in a strictly controlled environment. This environmental control covers mainly the temperature, humidity and vibrations [1]. For this reason, running costs of the laboratory are significant. As a result, it is highly required to shorten the time of weight measurements in order to increase the efficiency of operation of the weighing laboratory. Time of single mass measurement on laboratory weighing scale is connected with its dynamic characteristic. This characteristic is determined by the mechanical construction of the weighing scale as well as by its control algorithm. Whereas optimisation of the mechanical construction is problematic, due to stiffness and robustness requirements [2], the possibilities of optimisation of the weighing scale's control algorithm still seem to be significant.For optimisation process oriented on the control of laboratory weighing scale, the most important issue is the proper determination of both static and dynamic transfer functions, as well as function's parameters. Moreover, especially in the case of high resolution weighing scales, nonlinearities of these characteristics can't be neglected. As a result, development of the mathematical model for dynamic of a weighing scale requires both detailed analyses of physical processes and careful identification of the model's parameters on the base of experiments.