Adaptive filters in load cell response correction

Abstract

Abstract The load cell is a prime example of a sensor in which the measurand contributes markedly to the response parameters. The load is an important part of the inertial parameter, which means that the characteristic poles defining the response vary with the applied load. Thus, a simple linear filter with fixed roots can only be valid at one load value. In this paper we discuss the development of an adaptive digital filter which is able to adjust the real and imaginary parts of the complex roots of the cell response in accordance with the applied load. There is often a residual noise problem after the frequency response correction and this is also amenable to an adaptive filter approach. The technique is established by theoretical analysis and is justified by means of simulation and experimental results. It proves extremely effective with normal precision load cells and, even with other highly resonant structures, dramatically reduces the setting time. These methods introduce the possibility of manufacturing smart load cells that display no signs of resonance in their response.