AAU logo

Ketelsen, Søren

Søren Ketelsen

PROJECT TITLE: Electro-Hydraulic Linear Drive for Offshore Applications with Focus on Energy Efficiency and Dynamic Characteristics

PhD period: 2018.07.01 – 2021.06.30.
Section: Fluid Power and Mechatronic Systems
Research Programmes: Efficient, Intelligent and Reliable Fluid Power Technology
Supervisor: Torben O. Andersen
Co-Supervisors: Lasse Schmidt and Morten Kjeld Ebbesen, University of Agder
Contact Information

Collaborator: University of Agder, Norway.
Funding: SFI Offshore Mechatronics, Norway.


Linear hydraulic actuation systems are used in a wide variety of applications in the offshore industry, e.g. for actuating crane manipulators. The energy efficiency of such systems is typically in the range of 30-50%. The low efficiency can be related to how systems have evolved. System cost, robustness and performance have been the driving forces for years, leading to energy inefficient resistance based valve control being the preferred concept.
However, as cost of energy is of increasing importance to the end user, alternative designs are required.

The main objective of the PhD research is to investigate how pump controlled hydraulic cylinder drives suitable for offshore cranes can be designed. The drive system should be characterised by:
- Improved energy efficiency due to decreased throttle related losses
- Possibility of energy recuperation
- Good dynamic properties 
- High degree of scalability
- Passive load holding functionality to comply with safety regulations

Based on a systematic system topology investigation including a state-of-the-art review and dynamic simulations, the fundamental drive layout for detailed investigation is determined.
An extended model including thermo-energetic behaviour is formulated to obtain insights into how the drive should be designed to ensure oil temperatures being within recommended range.
Advanced control functionality both on drive and system (crane) level is developed. This may include oil temperature control, varying/adaptive drive stiffness control and path optimised tool center control.

The developed drive system is experimentally tested on a scaled crane manipulator and performance is compared to conventional valve controlled systems.


Publications in journals and conference papers may be found at VBN.