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Active heave compensation : ウィキペディア英語版 | Active heave compensation Active heave compensation (AHC) is a technique used on lifting equipment to reduce the influence of waves upon offshore operations. AHC differs from Passive Heave Compensation by having a control system that actively tries to compensate for any movement at a specific point, using power to gain accuracy. ==Principles== The purpose of AHC is to keep a load, held by equipment on a moving vessel, motionless with regard to the seabed or another vessel. Commercial offshore cranes usually use a Motion reference unit (MRU) or pre-set measurement position detection to detect the current ship displacements and rotations in all directions.〔(【引用サイトリンク】url=http://www.scantrol.no/scantrol-ahc-4 )〕 A control system, often PLC or computer based, then calculates how the active parts of the system are to react to the movement.〔(【引用サイトリンク】url=http://www.oilonline.com/default.asp?id=259&nid=37173&name=Active+heave+compensation+comes+of+age+subsea )〕 The performance of an AHC system is normally limited by power, motor speed and torque, by measurement accuracy and delay, or by computing algortithms. Choice of control method, like using preset values or delayed signals, may affect performance and give large residual motions, especially with unusual waves. State of the art AHC systems are real time systems that can calculate and compensate any displacement in a matter of milliseconds. Accuracy then depends on the forces on the system, and thus the shape of the waves more than the size of the waves.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Active heave compensation」の詳細全文を読む
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