0000000000334848
AUTHOR
Geir-arne Moslått
showing 7 related works from this author
Motion Control of Hydraulic Winch Using Variable Displacement Motors
2020
The paper II is excluded from the dissertation with respect to copyright. To compete in the open market of the offshore crane industry, it is imperative for the manufacturer to continuously improve crane operability. In this context, the crane operability is expressed by means of a so-called weather window. The weather window is computed from the crane characteristics in combination with that of the vessel and the payload to be handled. It returns a set of boundaries for when it is accepted to perform a planned lift, mainly in terms of current sea-state and wind. The most important crane operability characteristics that enter into the computation of the weather window are maximum wire veloc…
A Control Algorithm for Active/Passive Hydraulic Winches Used in Active Heave Compensation
2019
Abstract The most common active heave compensated offshore cranes have hydraulic winch systems. This paper investigates an active/passive hydraulic winch system with variable-displacement motors and variable-displacement pumps. The paper addresses the challenges when the active motors are set with a low displacement. The active motor displacement is shown to have significant impact on the dynamics of the closed loop hydraulic system. The classical control strategy for this type of system do not address these challenges and will in certain situations have significantly reduced performance. Therefor, a new control method is presented that utilize the variable displacement of the pumps and mot…
A Digital Twin for Lift Planning With Offshore Heave Compensated Cranes
2020
Abstract This paper presents a state-of-the-art digital twin of a hydraulic actuated winch that is used for heave compensation in offshore applications. The digital twin is used as part of a larger simulation model that involves all necessary components to perform lift planning and, subsequently, determine the corresponding weather window. The winch simulation model is described and verified by means of full-scale measurements. In addition, a set of acceptance criteria are presented that should be used whenever verifying digital twins of heave compensating winches that are to be used for lift planning.
Modeling of Friction Losses in Offshore Knuckle Boom Crane Winch System
2018
This paper presents a method for friction modeling in a hydraulically actuated multi motor winch system of an offshore knuckle boom crane. The method is based on a combination of a model of the variable displacement axial piston motor based on measurements from the sub supplier, and combined with a model of the remaining friction loss obtained from measurements on the full system.
Performance Improvement of a Hydraulic Active/Passive Heave Compensation Winch Using Semi Secondary Motor Control: Experimental and Numerical Verific…
2020
In this paper, a newly developed controller for active heave compensated offshore cranes is compared with state-of-the-art control methods. The comparison is divided into a numerical part on stability margins as well as operational windows and an experimental validation of the expected performance improvement based on a full-scale testing on site with a crane rated to 250 metric tons. Such a crane represents the typical target for the new control method using a combination of active and passive hydraulic actuation on the main winch. The active hydraulic actuation is a hydrostatic transmission with variable-displacement pumps and variable-displacement motors. The new controller employs feedf…
DESIGN OPTIMIZATION OF VERTICAL PIPE HANDLING SYSTEM
2012
Master's thesis Mechatronics MAS500 - University of Agder, 2012 Konfidensiell til / confidential until 01.07.2017
Practice for determining friction in hydraulic winch systems
2020
This paper presents a method for estimating friction in hydraulic active heave compensated (AHC) offshore winches. The method is a two-step approach where the first step is to model the friction loss in the hydraulic motors based on data from the sub-supplier. The second step requires real-life testing, where the remaining friction losses in the winch system is identified and modeled. In this context, a practice is characterized by obtaining a friction loss estimation with the highest possible accuracy over the widest possible range of operating conditions with a limited amount of experimental work. The method benefits from the use of parametric models, sub-supplier data, and real-life meas…