Crane control with active heave compensation

US8235231B2 · kind B2 · utility

Assignee

• LIEBHERR-WERK NENZING GMBH · AT

Inventors

• Klaus Schneider · Hergatz, DE
• Oliver Sawodny · Stuttgart, DE
• Joerg Neupert · Stuttgart, DE
• Tobias Mahl · Stuttgart, DE
• Sebastian Kuchler · Böblingen, DE

Key dates

• Filing date: May 20, 2009
• Grant date: Aug 7, 2012
• Expiry date: May 12, 2030

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B63B2017/0072
• WIPO field: Handling
• WIPO sector: Mechanical engineering

Abstract

The present invention represents a procedure for compensating the heave movement of offshore cranes. The dynamic model of the compensation actuator (hydraulically operated winch) and the load hanging on a rope are derived. Based on this model, a path-tracking control unit is developed. To compensate the movement of the ship/watercraft caused by waves, the heave movement is defined as a time-varying disturbance and is analyzed with respect to uncoupling conditions. With a model expansion, these conditions are satisfied, and an inversion-based uncoupling control law is formulated. To stabilize the system, an observer is used for reconstructing the unknown state by means of a force measurement. Furthermore, the compensation efficiency can be improved by predicting the heave movement. There is proposed a prediction method in which no ship/watercraft models or properties are required. The simulation and measurement results validate the heave compensation method.