Control system for a lifting device
US8125173B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | May 22, 2007 |
| Grant date | Feb 28, 2012 |
| Priority date | — |
| Expiry date | Oct 4, 2028 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66D3/18
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A control system for a lifting device in which a load moves up or down or maintains its position by a rope that is wound up or down by the rotation of a servo motor. It includes a device for measuring a force, a first controller, a second controller and a switching device. A total force that is applied at the lower part of the rope caused by a force for controlling, the mass of the load, and the acceleration of the load is measured. The first controller, based on the measured force computes the direction and the speed of the servo motor, and outputs a signal to it. The second controller determines a stable condition using Popov's stability criterion. The switching device replaces the first controller with the second controller when the value that is measured by the measuring device becomes less than a threshold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.