Automatic current control of magnet cranes for steel plate yard automation

Abstract

This paper presents an automatic current-control method for magnet cranes for thick steel plate yard automation. In moving the steel plates from stack to stack or from stack to shipping truck, it is difficult to lift the correct number of steel plates because the dimensions of the stacked steel plates are in general different, and their other parameters are not completely known and may even vary in a nonlinear fashion. In this paper, recursive form flux equations are first derived for the thick steel plates, and a current equation is then determined for the magnet coil. Based on these equations, an adaptive current predictor is developed to exert the right amount of current on the magnet, so as to lift the correct number of steel plates. When the initial trial with this current fails, a current tuning method is introduced to adjust the current and lift the correct number of plates. The developed magnet current controller has been successfully tested on data obtained from the storage yard at the Pohang Iron & Steel Co. (POSCO). (C) 1998 Published by Elsevier Science Lid. All rights reserved.