| 摘要 |
<p>Apparatus for measuring the length of a moving elongate element (1), such as a cable, comprises first and second rotative members (2), (3), rotatable by frictional contact with the element. The second member (3) responds to changes in the velocity of the element (1) to a differing extent to that of the first member (2). The rotation of each member is measured by detectors (11), (12), and data fed to a microprocessor (13) which compares the rotation of the two members to give an indication of the amount of slippage between one or both members and the element (1). The slippage is taken into account in determining the length of the moving element.</p><p>The differing response to changes in velocity can be achieved by the second member (3) being of a different inertia to that of the first member (2). Alternatively the members frictionally contact the element to a different extent.</p> |
