Publications

2023

1. 

   A ROS 2 and TwinCAT Based Digital Twin Framework for Mechatronics Systems

   A. Sterk-Hansen, B.H.H. Saghaug,  D.Hagen, and 1 more author

   11th International Conference on Control, Mechatronics and Automation (ICCMA 2023), 2023

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   This paper presents a digital twin framework as a first step towards developing digital twin-based control systems for autonomous lifting and load-handling operations. The pro- posed digital twin framework has been divided into three main parts: a) a real-time control and simulation environment using TwinCAT 3 running on a Beckhoff embedded PC with EtherCAT Fieldbus, b) a ROS 2 interface (middleware), and c) a virtual environment using the state-of-the-art game engine software NVIDIA Isaac Sim. The investigated case study demonstrates that the proposed architecture offers scalability and forms a promising baseline for further developing a general-purpose digital twin development platform suitable for developing autonomous control systems for various mechatronics systems and applications.

   @article{AlexBjorn2023,
     author = {Sterk-Hansen, A. and Saghaug, B.H.H. and D.Hagen and Aftab, M.F.},
     city = {Grimstad, Norway},
     journal = {11th International Conference on Control, Mechatronics and Automation (ICCMA 2023)},
     title = {A ROS 2 and TwinCAT Based Digital Twin Framework for Mechatronics Systems},
     year = {2023},
   }

2. 

   Antiswing Control and Trajectory Planning for Offshore Cranes

   R. Landsverk, J. Zhou, and D. Hagen

   49th Annual Conference of the IEEE Industrial Electronics Society (IECON 2023), 2023

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   Safe handling of heavy payloads in an offshore environment requires careful crane maneuvering to avoid collision with obstacles and other equipment. The residual swing from a hanging payload can ultimately lead to danger and high cost failures if not properly dealt with. This paper investigates an open- loop control method for eliminating the payload swing for hanging loads on offshore knuckle-boom cranes. A trajectory tracking method is designed for payload swing suppression for open-loop control and based on the iterative learning algorithm. It is shown that the proposed anti-swing control method guarantees asymptotic convergence of the swing, the angular velocity, and the angular acceleration of the payload using Lyapunov techniques. The simulation results show the superior performance of the proposed anti swing control method.

   @article{ronny2023,
     author = {Landsverk, R. and Zhou, J. and Hagen, D.},
     city = {Marina Bay Sands, Singapore},
     journal = {49th Annual Conference of the IEEE Industrial Electronics Society (IECON 2023)},
     title = {Antiswing Control and Trajectory Planning for Offshore Cranes},
     year = {2023},
   }

2022

1. 

   Development of a Novel Object Detection System Based on Synthetic Data Generated from Unreal Game Engine

   I. Rasmussen, S. Kvalsvik, P.-A. Andersen, and 2 more authors

   Applied Sciences, 2022

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   This paper presents a novel approach to training a real-world object detection system based on synthetic data utilizing state-of-the-art technologies. Training an object detection system can be challenging and time-consuming as machine learning requires substantial volumes of training data with associated metadata. Synthetic data can solve this by providing unlimited desired training data with automatic generation. However, the main challenge is creating a balanced dataset that closes the reality gap and generalizes well when deployed in the real world. A state-of-the-art game engine, Unreal Engine 4, was used to approach the challenge of generating a photorealistic dataset for deep learning model training. In addition, a comprehensive domain randomized environment was implemented to create a robust dataset that generalizes the training data well. The randomized environment was reinforced by adding high-dynamic-range image scenes. Finally, a modern neural network was used to train the object detection system, providing a robust framework for an adaptive and self-learning model. The final models were deployed in simulation and in the real world to evaluate the training. The results of this study show that it is possible to train a real-world object detection system on synthetic data. However, the models showcase a lot of potential for improvements regarding the stability and confidence of the inference results. In addition, the paper provides valuable insight into how the number of assets and training data influence the resulting model.

   @article{syntetic2022,
     author = {Rasmussen, I. and Kvalsvik, S. and Andersen, P.-A. and Aune, T.N. and Hagen, D.},
     doi = {10.3390/app12178534},
     issue = {17},
     journal = {Applied Sciences},
     title = {Development of a Novel Object Detection System Based on Synthetic Data Generated from Unreal Game Engine},
     volume = {12},
     year = {2022},
   }

2020

1. 

   A Method for Smoothly Disengaging the Load-Holding Valves of Energy-Efficient Electro-Hydraulic Systems

   Daniel Hagen, and Damiano Padovani

   Proceedings, Jan 2020

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   A novel self-contained, electro-hydraulic cylinder drive capable of passive load-holding, four-quadrant operations, and energy recovery was presented recently and implemented successfully. This solution greatly improved energy efficiency and motion control in comparison to the state-of-the-art, valve-controlled systems typically used in mobile and offshore applications. The passive load-holding function was realized by two pilot-operated check valves placed on the cylinder ports, where their pilot pressure was selected by a dedicated on/off electrovalve. These valves can maintain the actuator position without consuming energy, as demonstrated on a single-boom crane. However, a reduced drop of about 1 mm was observed in the actuator position when the load-holding valves were disengaged to enable the piston motion using closed-loop position control. Such a sudden variation in the piston position that was triggered by switching the load-holding valves could increase up to 4 mm when open-loop position control was chosen. For these reasons, this research paper proposes an improved control strategy for disengaging the passive load-holding functionality smoothly (i.e., by removing this unwanted drop of the piston). A two-step pressure control strategy is used to build up pressure before disengaging the pilot-operated check valves. The proposed experimental validation of this method eliminates the piston position’s drop highlighted before and improves motion control when operating the crane in open-loop position control. These outcomes benefit those systems where the kinematics amplify the piston motion significantly (e.g., in aerial platforms) increasing, therefore, operational safety.

   @article{hagenLHV2020,
     author = {Hagen, Daniel and Padovani, Damiano},
     doi = {10.3390/iecat2020-08478},
     journal = {Proceedings},
     month = jan,
     pages = {36},
     publisher = {MDPI AG},
     title = {A Method for Smoothly Disengaging the Load-Holding Valves of Energy-Efficient Electro-Hydraulic Systems},
     year = {2020},
   }

2. 

   Improving Energy Efficiency and Motion Control in Load-Carrying Applications using Self-Contained Cylinders

   Daniel Hagen

   Doctoral Dissertation at the University of Agder 283, Jan 2020

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   Because of an increasing focus on environmental impact, including CO2 emissions and fluid spill pollution, inefficient hydraulic systems are being replaced by more environmentally friendly alternatives in several industries. For instance, in some offshore applications that have multiple diesel generators continuously running to produce electricity, all hydraulic rotating actuators supplied from a central hydraulic power unit have been replaced with AC induction motors containing a variable frequency drive and gearbox. However, hydraulic linear actuators are still needed in most load-carrying applications mainly because of their high reliability associated with external impact shocks. Moreover, their force capacity is higher than that of their linear electromechanical counterparts. Valve-controlled linear actuators (cylinders) supplied from a centralized hydraulic power unit are standard in offshore load-carrying applications. In addition to the advantages mentioned above of hydraulic linear actuators, they have, nevertheless, a number of important drawbacks, which include: 1) a high level of energy consumption due to significant power losses caused by flow throttling in both the pipelines and valves, 2) reduced motion performance due to the influence of load-holding valves, 3) high CO2 emissions and fuel costs related to the diesel generator that supplies electricity to the hydraulic power unit, 4) significant potential for hydraulic fluid leakage because of many leakage points, 5) demanding efforts with respect to installation and maintenance, as well as 6) costly piping due to the centralized hydraulic power supply. The work presented in this dissertation and the appended papers are devoted to replacing inefficient hydraulic linear actuation systems traditionally used in offshore load-carrying applications with more environmentally friendly solutions. Two alternative technologies are identified, namely electro-mechanical and electro-hydraulic self-contained cylinders. The feasibility of replacing conventional valve-controlled cylinders with self-contained cylinder concepts is investigated in two relevant case studies.

   @article{hagenPhD2020,
     author = {Hagen, Daniel},
     journal = {Doctoral Dissertation at the University of Agder 283},
     title = {Improving Energy Efficiency and Motion Control in Load-Carrying Applications using Self-Contained Cylinders},
     year = {2020},
   }

3. 

   Guidelines to Select Between Self-Contained Electro-Hydraulic and Electro-Mechanical Cylinders

   D. Hagen, D. Padovani, and M. Choux

   15th IEEE Conference on Industrial Electronics and Applications, Jan 2020

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   This research paper presents guidelines on how to select between self-contained electro-hydraulic and electromechanical cylinders. An example based on the motion control of a single-boom crane is studied. The sizing process of the different off-the-shelf components is analyzed in terms of design impact when replacing a traditional valve-controlled hydraulic cylinder. The self-contained electro-hydraulic solution is the best choice when a risk for high impact forces is present, when the required output power level lies continuously above 2 kW, or when installation space, weight, and cost are critical design objectives. However, the electro-mechanical solution is expected to show more controllability due to the fact that it has higher levels of drive stiffness, and energy efficiency as well as lower system complexity. This solution also requires less effort to control the actuator’s linear motion accurately. All of these factors result in a more straightforward design approach.

   @article{Hagen2020,
     author = {Hagen, D. and Padovani, D. and Choux, M.},
     doi = {10.1109/ICIEA48937.2020.9248373},
     journal = {15th IEEE Conference on Industrial Electronics and Applications},
     title = {Guidelines to Select Between Self-Contained Electro-Hydraulic and Electro-Mechanical Cylinders},
     year = {2020},
   }

2019

1. 

   A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency

   D. Hagen, D. Padovani, and M. Choux

   Actuators, Jan 2019

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   This research paper presents the second part of a comparative analysis of a novel self-contained electro-hydraulic cylinder with passive load-holding capability against a state of the art, valve-controlled hydraulic system that is typically used in load-carrying applications. After addressing the control design and motion performance in the first part of the study, the comparison is now focused on the systems’ energy efficiency. It is experimentally shown that the self-contained solution enables 62% energy savings in a representative working cycle due to its throttleless and power-on-demand nature. In the self-contained drive, up to 77% of the energy taken from the power supply can be used effectively if the recovered energy is reused, an option that is not possible in the state of the art hydraulic architecture. In fact, more than 20% of the consumed energy may be recovered in the self-contained system during the proposed working cycle. In summary, the novel self-contained option is experimentally proven to be a valid alternative to conventional hydraulics for applications where passive load-holding is required both in terms of dynamic response and energy consumption. Introducing such self-sufficient and completely sealed devices also reduces the risk of oil spill pollution, helping fluid power to become a cleaner technology.

   @article{Hagen2019d,
     author = {Hagen, D. and Padovani, D. and Choux, M.},
     doi = {10.3390/act8040078},
     issue = {4},
     journal = {Actuators},
     pages = {78},
     title = {A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency},
     volume = {8},
     year = {2019},
   }

2. 

   A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 1: Motion Control

   D. Hagen, D. Padovani, and M. Choux

   Actuators, Jan 2019

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   This research paper presents the first part of a comparative analysis of a novel self-contained electro-hydraulic cylinder with passive load-holding capability against a state of the art, valve-controlled actuation system that is typically used in load-carrying applications. The study is carried out on a single-boom crane with focus on the control design and motion performance analysis. First, a model-based design approach is carried out to derive the control parameters for both actuation systems using experimentally validated models. The linear analysis shows that the new drive system has higher gain margin, allowing a considerably more aggressive closed-loop position controller. Several benefits were experimentally confirmed, such as faster rise time, 75% shorter settling time, 61% less overshoot, 66% better position tracking, and reduction of pressure oscillations. The proposed control algorithm is also proven to be robust against load variation providing essentially the same position accuracy. In conclusion, the novel self-contained system is experimentally proven to be a valid alternative to conventional hydraulics for applications where passive load-holding is required.

   @article{Hagen2019c,
     author = {Hagen, D. and Padovani, D. and Choux, M.},
     doi = {10.3390/act8040079},
     issue = {4},
     journal = {Actuators},
     pages = {79},
     title = {A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 1: Motion Control},
     volume = {8},
     year = {2019},
   }

3. 

   Enabling Energy Savings in Offshore Mechatronic Systems by using Self-Contained Cylinders

   D. Hagen, D. Padovani, and M. Choux

   Journal of Modeling, Identification and Control, Jan 2019

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   This paper proposes a novel actuation system for an offshore drilling application. It consists of three self-contained electro-hydraulic cylinders that can share and store regenerated energy. The energy saving potential of the proposed solution is analyzed through a multibody system simulation. The self-contained system demonstrates superior energy efficiency compared to the benchmark system representing the state-of-the-art approach used today (i.e., valve-controlled cylinders by means of pressure-compensated directional control valves and counter-balance valves, supplied by a centralized hydraulic power unit). Due to the power on demand capability, the cancellation of the throttling losses, and the opportunity to recover energy in motoring quadrants, the self-contained system consumes 83.44% less energy without affecting the system’s performance.

   @article{Hagen2019a,
     author = {Hagen, D. and Padovani, D. and Choux, M.},
     isbn = {10.4173/mic.2019.2.2},
     issue = {2},
     journal = {Journal of Modeling, Identification and Control},
     pages = {89-108},
     title = {Enabling Energy Savings in Offshore Mechatronic Systems by using Self-Contained Cylinders},
     volume = {40},
     year = {2019},
   }

4. 

   Design and Implementation of Pressure Feedback for Load-Carrying Applications with Position Control

   D. Hagen, D. Padovani, and M. Choux

   Sixteenth Scandinavian International Conference on Fluid Power, Jan 2019

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   This research paper presents the design and implementation of pressure feedback on a hydraulically actuated single-boom crane operated in closed-loop position control. It is well known that systems with pressure compensated proportional valves in combination with over-center valves tend to induce instability, especially when the external load is overrunning (e.g., while lowering a load). However, in some applications pressure oscillations arise also with resistant external loads (e.g., while lifting a load). Hence, a pressure feedbac k capable of stabilizing the system functioning in both operations using the pressures from both actuator chambers (i.e., piston-side and rod-side) is proposed and compared against the conventional solution using only the rod-side chamber pressure. The investigation demonstrates that the implementation of a propos ed "inverse valve dynamic" algorithm is needed in order for the control valve to stabilize the system when introducing the piston-side pressure in the pressure feedback. With this new method, the experimental tests demonstrate a satisfactory reduction of the pressure fluctuations in closed-loop motion control and a good position tracking (the average position error while lowering the load is reduced by almost 90% compared to the original system without pressure feedback). Finally, simulated results show that the proposed pressure feedback allows for potential energy savings of about 50% when lowering the load.

   @article{Hagen2019,
     author = {Hagen, D. and Padovani, D. and Choux, M.},
     city = {Tampere, Finland},
     journal = {Sixteenth Scandinavian International Conference on Fluid Power},
     title = {Design and Implementation of Pressure Feedback for Load-Carrying Applications with Position Control},
     year = {2019},
   }

5. 

   A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability

   D. Padovani, S. Ketelsen, D. Hagen, and 1 more author

   Energies, Jan 2019

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   Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost efficiency and power applications below five [kW]. Therefore, there is the need of developing more flexible systems adaptable to multiple applications. This research paper offers a contribution in this regard. It presents an electro-hydraulic self-contained single-rod cylinder with passive load-holding capability, sealed tank, capable of recovering energy, and scalable up to about eighty [kW]. The system implementation on a single-boom crane confirms its feasibility: The position tracking error remains well within ±2 [mm], oscillations are limited, and the overall energy efficiency is about 60 [%] during actuation. Concerning the passive load-holding devices, it is shown that both vented and non-vented pilot-operated check valves achieve the desired functioning and can hold the actuator position without consuming energy. Additional observations about the size and the arrangement of the load-holding valves are also provided. In conclusion, this paper demonstrates that the proposed self-contained cylinder can be successfully extended to several practical applications, especially to those characterized by overrunning external loads and the need of securing the actuator position.

   @article{Padovani2019,
     author = {Padovani, D. and Ketelsen, S. and Hagen, D. and Schmidt, L.},
     doi = {10.3390/en12020292},
     issue = {2},
     journal = {Energies},
     title = {A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability},
     volume = {12},
     year = {2019},
   }

2018

1. 

   Study of a Self-Contained Electro-Hydraulic Cylinder Drive

   D. Hagen, D. Padovani, and M. K. Ebbesen

   2018 Global Fluid Power Society PhD Symposium (GFPS), Jan 2018

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   Self-contained electro-hydraulic cylinders that can be powered just by an electrical wire will be popular in the coming years. Combining electrical-drives and hydraulic cylin- ders exploits some excellent properties of these two technologies and enables flexible implementation. To fully benefit from such a drive solution, there is the need to develop electro-hydraulic cylinders capable of operating independently as opposed to standard hydraulic systems that are connected to a central power supply. Therefore, this paper presents a numerical investigation of a self-contained electro-hydraulic cylinder with passive load- holding capability. The corresponding dynamic model is proposed and used to predict the system behavior with a view to future implementation. The simulations show the proposed drive guar- antees proper functioning in four-quadrant operations.

   @article{Hagen2018,
     author = {Hagen, D. and Padovani, D. and Ebbesen, M. K.},
     city = {Samara, Russia},
     doi = {10.1109/GFPS.2018.8472360},
     journal = {2018 Global Fluid Power Society PhD Symposium (GFPS)},
     title = {Study of a Self-Contained Electro-Hydraulic Cylinder Drive},
     year = {2018},
   }

2017

1. 

   Feasibility Study of Electromechanical Cylinder Drivetrain for Offshore Mechatronic Systems

   D. Hagen, W. Pawlus, M. K. Ebbesen, and 1 more author

   Journal of Modeling, Identification and Control, Jan 2017

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   Currently, there is an increasing focus on the environmental impact and energy consumption of the oil and gas industry. In offshore drilling equipment, electric motors tend to replace traditionally used hydraulic motors, especially in rotational motion control applications. However, force densities available from linear hydraulic actuators are still typically higher than those of electric actuators. Therefore, usually the remaining source of hydraulic power is thereby the hydraulic cylinder. This paper presents a feasibility study on the implementation of an electromechanical cylinder drivetrain on an offshore vertical pipe handling machine. The scope of this paper is to investigate the feasibility of a commercial off-the-shelf drivetrain. With a focus on the motion performance, numerical modeling and simulation are used when sizing and selecting the components of the considered electromechanical cylinder drivetrain. The simulation results are analyzed and discussed together with a literature study regarding advantages and disadvantages of the proposed solution considering the design criteria of offshore drilling equipment. It is concluded that the selected drivetrain can only satisfy the static motion requirements since the required transmitted power is higher than the recommended permissible power of the transmission screw. Consequently, based on the recommendation of the manufacturer, avoidance of overheating cannot be guaranteed for the drivetrain combinations considered for the case study presented in this paper. Hence, to avoid overheating, the average speed of the motion cycle must be decreased. Alternatively, external cooling or temperature monitoring and control system that prevents overheating could be implemented.

   @article{Hagen2017,
     author = {Hagen, D. and Pawlus, W. and Ebbesen, M. K. and Andersen, T. O.},
     doi = {10.4173/mic.2017.2.2},
     issue = {2},
     journal = {Journal of Modeling, Identification and Control},
     pages = {59-77},
     title = {Feasibility Study of Electromechanical Cylinder Drivetrain for Offshore Mechatronic Systems},
     volume = {38},
     year = {2017},
   }