Gangway control system and method

Abstract

The present invention relates to a control system and a corresponding method suitable for controlling a gangway structure gangway, crane or similar suitable for transferring personnel or goods to or from a floating structure such as a sea vessel relative to a fixed or moving landing point. The system including global position measurement of the position of the floating structure and the position of the landing point, and thus a first relative position between the floating structure and the landing point, and a control unit configured to move the gangway relative to the landing point. The system also includes a local position measurement unit positioned at or in relation to the distal end of the gangway being configured to measure a second relative position between the landing point and the gangway distal end, the local position measurement unit being connected to the control system unit so as to communicate the second relative position to the control system unit. The system is configured to adjust the first relative position based on the second relative position resulting in a corrected reference signal, the control unit being configured to adjust the position of the gangway so as to position the gangway distal end to the desired position relative to the landing point.

1 - 7 . (canceled) 
     
     
         8 . A control system for controlling a gangway structure on a floating structure to a desired position relative to a fixed or moving landing point, the control system comprising global position measurement system providing a measurement of the global position of the floating structure and the global position of the landing point, and based on these being configured to calculate a first relative position between the floating structure and the landing point, and a control unit configured to move the gangway relative to the landing point, the system also including a local position measurement unit positioned at or in relation to the distal end of the gangway being configured to measure a second relative position between the landing point and the gangway distal end, the local position measurement unit being connected to the control system unit so as to communicate the second relative position to the control system unit, the system being configured to, based on the first and second relative positions, to provide a combined data set representing the position error measured by the local position measurements unit and to adjust the first relative position based on the second relative position resulting in a corrected reference signal, the control system being configured to adjust the position of the gangway based on the corrected reference signal so as to position the gangway distal end to the desired position relative to the landing point. 
     
     
         9 . The system according to  claim 8 , wherein the corrected reference signal is derived by a combination of first and second relative position, wherein the combination of the first and second measurement provides a closed loop system. 
     
     
         10 . The system according to  claim 8 , wherein the bandwidth of the communicated second relative position is filtered so as to correspond to a predetermined bandwidth range of the gangway movements. 
     
     
         11 . The system according to  claim 8 , wherein the second relative position is added to the reference position of the landing point, thus biasing the reference position. 
     
     
         12 . The system according to  claim 11 , wherein the second relative position is added to the first reference position of the floating structure, thus adjusting the global position data. 
     
     
         13 . The system according to any of the previous claims, wherein the second relative position is measured using an imaging device configured to recognize a feature on the landing point. 
     
     
         14 . A method for controlling a gangway on a floating structure, the gangway comprising a global positioning system measuring the global position of the floating structure, and the gangway with a distal end configured to be positioned in a predetermined position relative to a landing point, the landing point having a known global reference position, the method comprising:
 providing a first relative position between the floating structure position and the landing point position;   measuring a second relative position between the landing point and the predetermined position of the distal end of the gangway relative to the landing point;   calculating a combined data set representing the position error based on the first and second relative positions and adjusting the first relative position based on the second relative position; and   controlling the distal end of the gangway on the floating structure into the predetermined position based on the adjusted first relative position.