Method of weight measurement using moving weigh conveyor

Abstract

A control for a weigh scale associated with a continuously moving conveyor which is capable of mathematically positioning the sample period on each product weight waveform. The control first triggers on a predetermined sensed weight. The control determines a first inflection point on the weight waveform defined as the “maximum positive slope.” Once the maximum positive slope is found, the control begins recording weight samples at a sampling rate. The control checks the weight waveform of sampled weights for a slope which is a first pre-selected percentage of the maximum slope but negative in slope value. This point is determined as the “weight-off-scale” point. When the weight-off-scale point is reached, then the control looks backward through the recorded data of weight samples to find another point which has a slope which is a second preselected negative percentage of the maximum positive slope. This point is defined as the “end sample position.” With the end sample position known, a “start sample position” is determined to fall within, or at the start of, a flat region of the waveform, such that the weight values within a sample period between the start and end sample positions are substantially constant. The weight values within the sample period are then averaged to determine a static weight value.