Motion control of hydraulic winch using variable displacement motors
The results of using the new proposed controller have been positive and indicate significant potential for improving capacity and performance.
Geir-Arne Moslått
PhD Candidate
The disputation will be held digitally, because of the Corona covid-19-situation. Spectators may follow the disputation digitally – link is available below.
Geir-Arne Moslått of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled “Motion Control of Hydraulic Winch Using Variable Displacement Motors” and will defend the thesis for the PhD-degree Wednesday 16 December 2020.
He has followed the PhD-programme at the Faculty of Engineering and Science, with spesialisation in Engineering Sciences, scientific field Mechatronics.
Geir-Arne Moslått has followed the Industrial Ph.D. scheme, where a company - in this project National Oilwell Varco - collaborates with a university - in this project the University of Agder - or university college on a doctoral project. The doctoral project is carried out by an employee and must be of clear relevance to the company’s activities..
Summary of the thesis by Geir-Arne Moslått:
Motion control of hydraulic winch using variable displacement motors
The target was to better utilize the active heave compensated offshore cranes and increase the weather window for offshore lifting operations.
This was done by analyzing and measure losses in the hydromechanical system and by investigating new control strategies.
Crane-data investigated
Several cranes with lifting capacity up to 165 tons have been investigated, and measurements have been taken to identify hydromechanical and volumetric losses in pumps and motors.
Additionally, the remaining friction in the winch system has been investigated.
This has been documented in three published articles:
- "Modeling of friction losses in offshore knuckle boom crane winch system"
- "A model for torque losses in variable displacement axial piston motors"
- "Practice for determining friction in hydraulic winch systems".
A new control strategy
The gathered data from measurements have been used to identify parameters in the developed loss models and implemented in a digital twin simulation model, which has been used to test a new control strategy.
The results from the new controller testing have resulted in two papers:
- "A control algorithm for active/passive hydraulic winches used in active heave compensation"
- "Performance Improvement of a Hydraulic Active/Passive Heave Compensation Winch Using Semi Secondary Motor Control: Experimental and Numerical Verification".
A significant improvement potential
The results of using the new proposed controller have been positive and indicate significant potential for improving capacity and performance.
The work with making and verifying the digital twin resulted in the last paper:
- "A digital twin for lift planning with offshore heave compensated cranes"
which was published in Journal of Offshore Mechanics and Arctic Engineering.
Disputation facts:
The trial lecture and the public defence will take place online, via the Zoom conferencing app (link below)
Vice Dean for Research, Professor Andreas Prinz, Faculty of Engineering and Science, University of Agder, will chair the disputation. Head of the Department of Engineering Sciences, Professor Geir Grasmo, Faculty of Engineering and Science, University of Agder, will chair the trial lecture.
The trial lecture at 10:15 hours
Public defence at 12:15 hours
Given topic for trial lecture: “Hydraulic piston motors for crane winches: Mechanical design principles, controllability, challenges in the low speed range”
Thesis Title: “Motion Control of Hydraulic Winch Using Variable Displacement Motors”
Search for the thesis in AURA - Agder University Research Archive, a digital archive of scientific papers, theses and dissertations from the academic staff and students at the University of Agder.
The thesis is available here:
https://hdl.handle.net/11250/2711317
The Candidate: Geir-Arne Moslått (1987, Fredrikstad) Masters degree in mechatronics UiA (2012) Master thesis: «Design Optimization of Vertical Pipe Handling System”
Opponents:
First opponent: Associate Professor Bernhard Manhartsgruber, Johannes Kepler University, Linz, Austria
Second opponent: Associate Professor Per Johansen, Department of Energy Technology, Aalborg University, Denmark
Associate Professor Sverre Lunøe-Nielsen, Department of Engineering Sciences, University of Agder, is appointed as the administrator for the assessment commitee.
Supervisors were Professor Michael Rygaard Hansen, UiA (main supervisor), Associate Professor Damiano Padovani, UiA and Manager Software and Automation Anders Meisfjordskar, NOV - National Oilwell Varco (co-supervisors)
What to do as an audience member:
The disputation is open to the public, but to follow the trial lecture and the public defence, which is transmitted via the Zoom conferencing app, you have to register as an audience member.
We ask audience members to join the virtual trial lecture at 10:05 at the earliest and the public defense at 12:05 at the earliest. After these times, you can leave and rejoin the meeting at any time. Further, we ask audience members to turn off their microphone and camera and keep them turned off throughout the event. You do this at the bottom left of the image when in Zoom. We recommend you use ‘Speaker view’. You select that at the top right corner of the video window when in Zoom.
Opponent ex auditorio:
The chair invites members of the public to pose questions ex auditorio in the introduction to the public defense, with deadlines. It is a prerequisite that the opponent has read the thesis. Questions can be submitted to the chair, Vice Dean for Research, Professor Andreas Prinz at e-mail andreas.prinz@uia.no