| 摘要 |
<p>Rope movement is detected through a rope movement change quantity at predetermined time intervals and the rope movement quantity is obtained by the accumulated value of the change quantities. When a hook structure reaches a spiral length position, the accumulated rope movement value is reset automatically to zero to update the reference position of rope movement, and measurement error of rope movement is corrected. The hook structure suspension length from the tip of a boom or jib is determined from the rope movement quantity thus obtained, and the hook lift is calculated. The hook lift or hook structure position thus calculated is displayed on a display with reference to a fixed index or pattern and the operator can monitor the behavior of the hook structure on the display. <IMAGE></p> |
