Application of ARMA modeling to the improvement of weight estimations in fruit sorting and grading machinery

Accurate weighting of pieces in different sorts of conveyor belts or articulated chains at fast speed is a key feature in many industrial processes. This paper presents a procedure to improve the performance, whether increasing speed or accuracy, of the load-cell-based weighting subsystem in a fruit sorting and grading machine to achieve an accuracy of ±1 gram at a speed of 20 fruits per seconds. The proposed solution includes a signal preprocessing based on a previous ARMA modeling of the weighting subsystem response plus a power line-noise removal and a simple sample averaging in the plateau. The procedure has been tested off-line using real signals acquired from a prototype machine