Abstract
Spreaders and lifters of cranes are usually controlled to stop when their trolleies are stopped. Despite the adequate control, however, the swing of the lifters does not vanish, and is considerably large due to the free suspension of the lifters from the ceilings through pullies with two wires. It is therefore important to measure the attitude of the lifters on-line in order to suppress the swing by another adequate control.
As one approach there is an image processing method which measures the attitude by tracking a mark on the lifter with a camera. This, however, requiring much cost in the equipment and maintenance, the paper proposes a maintenance free automatic measurement system, which enables an accurate on-line measurement of the attitude of the lifters. For realizing the system, the lifter system is modeled by a linear dynamic one of a double pendulum and a Kalman filter is used. To extract the information on the swing of the lifter, one servo-type accelerometer is mounted on the lifter.
