High-Precision Measurement of Spreader's Sway in Transfer Cranes Based on Detection of Camera Attitude

Abstract

From the viewpoints of safety operation and efficiency of transfer cranes, spreaders (suspended from the trolleys) are controlled to stop as quickly as possible when the trolleys are stopped. It is therefore important to measure the sway of the spreaders accurately. For this purpose, a CCD camera has been used which was attached on the bottom of the trolley. However, the accuracy of the measurement was insufficient because of the deflection of the camera axis from the vertical line. The paper thus first considers the real-time measurement of the deflection in the camera attitude (against the vertical line) based on the analysis of the dynamics of the girder system and strain gauges attached on the girder, and next presents a high-precision measurement of the sway of the spreader.