Set-Point Algorithms for Active Heave Compensation of Towed Bodies

Abstract

Active heave compensation is a technique used in marine applications to attenuate undesirable wave motions between a load and its host vessel. Motion attenuation is often achieved by reeling in or reeling out a cable tethering the load to the host vessel in response to the host vessel’s heave motion. Most applications of active heave compensation are single degree-of-freedom systems which only operate vertically. In order to apply active heave compensation to towed bodies – which experience significant multiple degree-of-freedom disturbances – a “set-point algorithm” is required which determines the length of tow cable that should be reeled in or reeled out in response to external wave motion. This thesis proposes, implements, and assesses four different set-point algorithm approaches in experimental and simulated environments.