A New Control Algorithm for the Grab-Swing Elimination in the Automatic Operation of Travelling Cranes

Abstract

In the automatic operation of travelling cranes the velocity of a trolley must be controlled so that the swing of its grab just vanishes when the trolley has arrived at a goal position. This paper describes a new control algorithm for such a grab-swing elimination. In this control algorithm the total travelling distance is divided into halves. In the first half, the trolley may be run with any velocity pattern and a program control scheme is employed. The swing angle of the grab and the actual velocity of the trolley are measured and stored into a data memory in the controller. In the latter half, both the trolley velocity and the grab swing-angle are controlled with a linear feedback control scheme. The stored data are read out from the data memory in the“last-in first-out”mode and used as the reference signals. This algorithm has been implemented on a microcomputer and used to control a crane model of 1m high and 2.5m long. The maximum swing angle remained at the goal position was ±3 degrees.