In or relating to crawlers

Abstract

A dual-mode crawler unit for traversing a generally tubular target, the unit comprising means for effecting a hand-over-hand action along the target and also means for effecting a driven action along the target, the unit comprising two or more traversing units, the units being directly connected to each other by one or more linear actuators.

What is claimed: 
     
         1 ) A dual-mode crawler unit for traversing a generally tubular target, the unit comprising two or more traversing modules which can effect a hand-over-hand action along the target and also a driven action along the target, the units being connected to each other by one or more linear actuators. 
     
     
         2 ) A unit as claimed in any  claim 1 , in which the modules comprise drive means selected from: rollers, tracks, wheels, thrusters, rolling support means, bristle drive or the like for effecting a driven action along the target. 
     
     
         3 ) A unit as claimed in  claim 1 , in which the modules comprise clamps for effecting a hand-over-hand action. 
     
     
         4 ) A unit as claimed in  claim 3 , in which the clamps are capable of moving toward and away from each other along the target. 
     
     
         5 ) A unit as claimed in  claim 1 , in which there are two sets of driven rollers, tracks or wheels separated by a linear actuator, and in which each set of driven rollers or tracks is capable of supporting and propelling the unit/tool along the target without the other being in contact with the target. 
     
     
         6 ) A unit as claimed in  claim 1 , comprising a roller, track or wheel capable of rotating the unit about the tubular target. 
     
     
         7 ) A unit or tool as claimed in  claim 2 , in which the drive means are movable between a retracted position and an engaged position. 
     
     
         8 ) A unit as claimed in  claim 1 , including thrusters for traversing the target and/or for keeping the unit concentric with the target during movement. 
     
     
         9 ) A unit as claimed in  claim 1 , including sensors for keeping the unit concentric with the target. 
     
     
         10 ) A unit as claimed in  claim 1 , including capability to adjust clockwise or anticlockwise rotation bias. 
     
     
         11 ) A unit as claimed in  claim 1 , which incorporates a sensor for giving its rotational position, either absolute, or relative to a datum. 
     
     
         12 ) A unit as claimed in  claim 1 , where a control system is used to automatically adjust clockwise or anticlockwise bias to maintain a desired rotational position or path on the target. 
     
     
         13 ) A unit as claimed in  claim 1 , where the modules include clamps for effecting hand-over-hand action comprise clamps and the clamps include a set of overlapping fingers forming an aperture, which retain the target when the clamps are opened, and centralize the target as the clamps are closed. 
     
     
         14 ) A unit as claimed in  claim 1 , including an on-board electrically driven HPU. 
     
     
         15 ) A unit as claimed in  claim 1 , including a module for cleaning the target. 
     
     
         16 ) A unit or tool as claimed in  claim 15 , in which the module cleans the target by scraping and/or rotating brushes and/or water jetting. 
     
     
         17 ) A unit or tool as claimed in  claim 1 , including a sensor or inspection module. 
     
     
         18 ) A unit as claimed in  claim 1 , including a set of subsea thrusters to enable the unit to swim, so to position itself around the target when in water. 
     
     
         19 ) A subsea bi-directional crawler unit for traversing a generally tubular target, in which the unit includes capability to monitor and correct rotational position, the unit comprising a sensor for providing absolute or relative rotation to a target and the ability to actively rotate the unit. 
     
     
         20 ) A crawler unit comprising a frame with a generally central roller set, a pair of lateral roller sets being provided on or by each side of the frame and being movable from an open position in which the frame can be positioned on a tubular target with the central roller set engaged, and a closed position in which the lateral roller sets are closed around the target and engage thereon.