Motion Reference Unit (MRU)

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Heave compensation systems have the ability to compensate the movement of a ship. This occurs by measuring the movement by means of MRU (motion reference unit) acceleration sensors. The data is relayed to the main controller that uses the information to control – depending on the type of AHC - a hydraulic motor connected directly to a winch (RAHC), a variable pump (PAHC) or a proportional valve (LAHC). These components power the winch so that the load hangs idle relative to the fixed world (i.e. the drilling rig or the seabed).