Daniel Hagen

• Dalal, Anurag; Hagen, Daniel; Robbersmyr, Kjell Gunnar & Knausgård, Kristian Muri (2026). Fast 3D Foundation Model Initialized Gaussian Splatting. 2026 6th International Conference on Electrical, Computer and Energy Technologies (ICECET). doi: 10.1109/icecet65726.2026.11633076. Full text in Research Archive Show summary

  This paper introduces a fast method for high-quality 3D Gaussian Splatting (3DGS) reconstruction without traditional Structure-from-Motion (SfM). The proposed approach leverages 3D Foundation Models (3DFMs) for camera pose and pointcloud initialization, then jointly optimizes both camera poses and Gaussian primitives using a depth-guided loss function. This enables fast convergence even from rough initialization with as few as 50-60 input views. To further improve reconstruction quality in sparse-view scenarios, an MLP-based pose refinement module is introduced alongside depth-guided supervision from the foundation model. Extensive experiments on Mip-NeRF 360, Tanks and Temples, and RobustNeRF demonstrate that the proposed method achieves competitive reconstruction quality (23.61 dB PSNR, 0.19 LPIPS) while reducing training time to approximately three minutes per scene. The proposed method produces ready-to-use 3DGS models at a fraction of the time required by existing pipelines, making it suitable for near realtime applications in robotics, VR, and autonomous navigation.

• Hagen, Daniel & Østerholt, Lars (2026). Distributed embedded digital twins for real-time coordinated operations: framework and proof-of-concept. Proceedings - European Council for Modelling and Simulation (ECMS). ISSN 2522-2414. 40(1), p. 267–276. doi: 10.7148/2026-0267. Full text in Research Archive Show summary

  This paper presents a distributed Embedded Digital Twin (EDT) framework for real-time coordinated multi-machine operations. An EDT integrates a real-time mathematical model, state estimation through sensor fusion, and control on the machine's own industrial embedded hardware, forming the intelligent system that drives the physical asset. In the proposed distributed architecture, each machine maintains its own EDT and shares state information with neighbouring machines over a deterministic industrial fieldbus, enabling coordination without central servers or middleware. The framework is demonstrated through a proof-of-concept in which a vessel EDT and a crane EDT execute on separate Beckhoff industrial PCs connected via EtherCAT, performing coordinated heave compensation. The crane EDT is benchmarked against an experimentally validated plant model, and the intra-IPC real-time performance is characterised. Future work will extend the framework by fusing EDT predictions with real sensor data from a physical system.

• Langås, Even Falkenberg; Aalerud, Atle; Nyberg, Svein Olav Glesaaen; Zafar, Muhammad Hamza; Hagen, Daniel & Sanfilippo, Filippo (2026). Predictive Human Trajectory Classification in Industrial Settings with Transfer Learning and Data Augmentation. IEEE Access. 14, p. 47071–47084. doi: 10.1109/ACCESS.2026.3677599. Full text in Research Archive Show summary

  The successful realisation of Industry 5.0 relies on seamless collaboration between humans and robots in shared workspaces. This paper investigates predictive human trajectory classification (HTC) in a factory setting to enhance safety, productivity, and adaptability in human-machine environments. Using a state-of-the-art light detection and ranging (LiDAR) system with reflective mirrors to extend the field of view, motion data are collected across a 26 m ×20 m indoor industrial floor. Human trajectories are classified to predict workstation transitions using a stacked long-short term memory (LSTM) network. To address the challenges of limited real-world data, transfer learning is applied by first training the model on synthetically generated trajectories. The paper compares a traditional stochastic method, specifically the Ornstein-Uhlenbeck (OU) process, with a modern learning based method, represented by a timeseries generative adversarial network (TimeGAN). Further on, the algorithm is fine-tuned on the real-world dataset. The comparison shows that in data-scarce scenarios, OU outperforms TimeGAN in most metrics. The LSTM model trained on OU-based data and real-world data shows an overall accuracy gain of 4.8 percentage points compared to training on real-world data only. It is able to classify the goal workstation three seconds in advance with an accuracy of 95.6%, demonstrating the potential for predictive models to improve workplace operations by reducing stall time, optimising workstation readiness, and reducing the need for traditional safety cages.

• Østerholt, Lars; Gundersen, Are; Zhou, Jing & Hagen, Daniel (2025). Real-Time Markerless Vision-Based Control of Knuckle Boom Cranes via Embedded AI. International Conference on Control, Mechatronics and Automation. ISSN 2837-5114. 2025. doi: 10.1109/iccma67641.2025.11369496. Full text in Research Archive Show summary

  This paper presents a load-handling system for a knuckle boom crane, integrating edge-AI-based computer vision, real-time control, and Screw theory kinematics. Utilizing YOLOv6-N for object detection and a camera-driven control system, the approach enables payload navigation in industrial environments without external markers. Key contributions include a markerless vision-based framework, real-time PLC implementation for control, and experimental validation of autonomous navigation across four distinct landing zones, demonstrating robust performance in dynamic settings. All without the need for external infrastructure. The system’s design minimizes setup complexity and enhances adaptability to diverse conditions.

• Dalal, Anurag; Hagen, Daniel; Robbersmyr, Kjell Gunnar & Knausgård, Kristian Muri (2025). ScatteringSplatting: Capturing Minute Details Using Deep Learning-Aided Gaussian Splatting. International Conference on Control, Mechatronics and Automation. ISSN 2837-5114. p. 547–554. doi: 10.1109/iccma67641.2025.11369605. Full text in Research Archive Show summary

  3D reconstruction in scattering media, such as underwater or foggy environments, presents significant challenges as well as substantial opportunities. Recent advances in novel view synthesis and accurate 3D reconstruction have enabled applications across diverse domains—from ecosystem monitoring and virtual observatories to underwater inspection and exploration using autonomous underwater vehicles and remotely operated vehicles. While Neural Radiance Fields excel at capturing environments with complex lighting effects, their long training times can limit practical applications. In contrast, 3D Gaussian Splatting offers a faster and more explainable alternative for 3D reconstruction and novel view synthesis. The proposed ScatteringSplatting method integrates volumetric rendering with 3D Gaussian Splatting to efficiently reconstruct underwater and foggy scenes. It explicitly separates the scattering media effects, handled via a multi-layer perceptron, from the 3D object geometries processed through Gaussian Splatting, and uses a unique loss function and effective culling of Gaussians to remove unwanted floaters. The primary advantage of our approach becomes evident when generating detailed views, particularly in rendering precise textures and small objects, such as fish. Our method achieves average PSNR, SSIM, and LPIPS scores of 28.91, 0.905, and 0.149, respectively, on the SeaThru-NeRF dataset.

• Dalal, Anurag; Hagen, Daniel; Robbersmyr, Kjell Gunnar & Knausgård, Kristian Muri (2025). Evaluating the effect of image quantity on Gaussian Splatting: A statistical perspective. Computer Vision and Image Understanding. ISSN 1077-3142. 263. doi: 10.1016/j.cviu.2025.104575. Full text in Research Archive Show summary

  3D reconstruction is now a key capability in computer vision. With the advancements in NeRFs and Gaussian Splatting, there is an increasing need on properly capturing data to feed these algorithms and use them in real world scenarios. Most publicly available datasets that can be used for Gaussian Splatting are not suitable to do proper statistical analysis on reducing the number of cameras or the effect of uniformly placed cameras versus randomly placed cameras. The number of cameras in the scene significantly affects the accuracy and resolution of the final 3D reconstruction. Thus, designing a proper data capture system with a certain number of cameras is crucial for 3D reconstruction. In this paper UnrealGaussianStat dataset is introduced, and a statistical analysis is performed on decreasing viewpoints have on Gaussian splatting. It is found that when the number of cameras is increased after 100 the train and test metrics saturates, and does not have significant impact on the reconstruction quality.

• Zhu, Mingda; Eidsvik, Johannes Arnesen; Landsverk, Ronny; Hagen, Daniel & Zhou, Jing (2025). Rapid Model-Based Design and Real-Time Digital Twin Integration: An Offshore Robot Case Study. Proceedings of the IEEE International Symposium on Industrial Electronics. p. 1–6. doi: 10.1109/isie62713.2025.11124748. Full text in Research Archive Show summary

  The rapid advancement of digitalization has led to the widespread adoption of digital twins across various industries. While digital twins have demonstrated significant potential in many applications, challenges remain in their implementation, particularly in real-time control. Therefore, this paper addresses the challenges by proposing a DT-based method for fast prototyping of real-time control in medium-scale industrial robots, leveraging rapid model-based design. With Speedgoat and the User Datagram Protocol communication protocol, the proposed approach enables real-time data exchange and control execution. The effectiveness of the method is demonstrated through four case studies by utilizing the Comau robot at the Norwegian Motion Laboratory.

• Zhu, Mingda; Han, Peihua; Landsverk, Ronny; Strandene, Jan Christian Bjerke; Hagen, Daniel & Zhou, Jing (2025). A Data-driven Approach to Payload Heave Motion Prediction under Irregular Waves, IEEE Industrial Electronics Society Annual On-Line Conference (ONCON). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798350357981. doi: 10.1109/ONCON62778.2024.10931669. Full text in Research Archive Show summary

  Effective handling of the payload with an offshore crane is critical for ensuring safety and efficiency in the offshore operation. Accurate modelling of payload heave motion is essential for safeguarding transportation and improving feedback control for active heave compensation. Traditional kinematic modelling fails to account for the nonlinear dynamics of waveinduced motion. This paper proposes a data-driven method,leveraging real motion data from the Norwegian Motion Lab, to predict payload heave positions based on ship heave positions. Extensive experiments are carried out using a diverse dataset under various sea states, and the proposed method is evaluated against three methods from different disciplines. The results demonstrate that the data-driven approach outperforms the compared methods, showing a better overall performance across multiple wave scenarios.

• Hagen, Daniel; Hansen, Katrine Als; Holmen, Jonas & Hansen, Michael Rygaard (2025). Real-Time Simulation-Based Control of an Electro-Hydraulic Flexible Manipulator. Actuators. 14(2). doi: 10.3390/act14020080. Full text in Research Archive Show summary

  This paper presents the modeling and control of a flexible single-boom crane manipulator using a high-fidelity real-time simulation model. The model incorporates both electro-hydraulic actuation and flexible-body dynamics, with the flexible boom represented via the lumped parameter method. A systematic tuning and validation procedure ensures that the model accurately replicates the physical system’s dynamics, achieving an eigenfrequency accuracy of approximately 97% and a piston-position deviation within 1.2% of the overall stroke length in final tests. The real-time simulation model is utilized in both open-loop and closed-loop control schemes to investigate whether simulated data can reduce dependency on sensor feedback compared to a benchmark controller. While the simulation-based controller alone does not match the fully sensor-based closed-loop accuracy, the simulation-based feedforward improves performance by 83% compared to the standard model-based velocity feedforward. Additionally, integrating the real-time simulation with sensor feedback enhances the benchmark controller’s performance by approximately 16%. These findings highlight the potential of combining real-time, nonlinear simulation with conventional sensor feedback to enhance the control of electro-hydraulic flexible manipulators.

• Dalal, Anurag; Hagen, Daniel; Robbersmyr, Kjell Gunnar & Knausgård, Kristian Muri (2024). Gaussian Splatting: 3D Reconstruction and Novel View Synthesis: A Review. IEEE Access. 12, p. 96797–96820. doi: 10.1109/ACCESS.2024.3408318. Full text in Research Archive
• Hagen, Daniel; Mæland, Martin; Skotterud, Tarjei; Hermansen, Martin Dahlseng; Haij, Husam Zain Mohammed & Wad, Martin Sauar (2024). UiAbot: A Versatile Autonomous Mobile Robot Platform for Research and Education. IEEE Conference on Industrial Electronics and Applications. doi: 10.1109/ICIEA61579.2024.10664856. Full text in Research Archive Show summary

  This paper presents UiAbot, an innovative autonomous mobile robot platform developed at the University of Agder to bridge the gap in hands-on robotics education. Using cost-effective sensors and the Robotic Operating System with the Navigation Stack, this internally developed platform facilitates advanced autonomous navigation, surpassing predecessors such as the TurtleBot3 in flexibility, functionality, and affordability. Integrated into master courses and research, the UiAbot demonstrates its effectiveness as an educational and research platform, showcasing the impact of open source technologies in democratizing robotics research and enhancing educational methodologies in autonomous systems.

• Sterk-Hansen, Alexander; Saghaug, Bjørn; Hagen, Daniel & Aftab, Muhammad Faisal (2024). A ROS 2 and TwinCAT Based Digital Twin Framework for Mechatronics Systems. International Conference on Control, Mechatronics and Automation. ISSN 2837-5114. p. 485–490. doi: 10.1109/ICCMA59762.2023.10374978. Full text in Research Archive Show summary

  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 proposed 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.

• Langås, Even Falkenberg; Bukhari, Halima Zahra; Hagen, Daniel; Zafar, Muhammad Hamza & Sanfilippo, Filippo (2024). Inclusive Digital Twins with Edge Computing, Cloud Communication and Virtual Reality to Achieve Remote Human-Robot Interaction. In NN, . (Eds.), 12th International Conference on Control, Mechatronics and Automation (ICCMA). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798331517519. p. 323–329. doi: 10.1109/ICCMA63715.2024.10843896. Full text in Research Archive Show summary

  Digital twins, advanced robotics, edge computing, and immersive technologies have come together to create novel solutions that increase flexibility and operating efficiency. This work is motivated by the need to harness these advancements to develop a robust architecture that supports edge intelligence and real-time remote monitoring and control. The aim of this work is to define a comprehensive framework for digital twins of complex mechatronic systems. The framework enables seamless connection between the physical environment and a virtual representation accessible from remote locations. Key components of the framework include the Robot Operating System 2 (ROS 2) for robot control, Node-RED for data processing and edge communication, a Message Queuing Telemetry Transport (MQTT) broker for cloud-based communication, and a virtual reality (VR) application for immersive interaction. A case study is presented to demonstrate the framework’s capabilities. Through the VR application, users can interact with a digital twin of a mechatronic system consisting of a collaborative robot, a programmable logic controller (PLC), a conveyor belt and numerous sensors. The user interface lets the operator manipulate the robot and monitor sensor data in real-time. Latency is measured to validate the performance of the framework, resulting in a mean latency of around 116 ms.

• Landsverk, Ronny; Zhou, Jing & Hagen, Daniel (2024). Antiswing Control and Trajectory Planning for Offshore Cranes: Design and Experiments. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. 45(4), p. 115–126. doi: 10.4173/mic.2024.4.1. Full text in Research Archive
• Landsverk, Ronny; Zhou, Jing & Hagen, Daniel (2023). Antiswing Control and Trajectory Planning for Offshore Cranes. Proceedings of the Annual Conference of the IEEE Industrial Electronics Society (IECON). ISSN 1553-572X. doi: 10.1109/IECON51785.2023.10312101. Full text in Research Archive Show summary

  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 openloop 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.

• Rasmussen, Ingeborg; Kvalsvik, Sigurd; Andersen, Per-Arne; Aune, Teodor N. & Hagen, Daniel (2022). Development of a Novel Object Detection System Based on Synthetic Data Generated from Unreal Game Engine. Applied Sciences. 12(17). doi: 10.3390/app12178534. Full text in Research Archive Show summary

  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.

• Hagen, Daniel & Padovani, Damiano (2020). A method for smoothly disengaging the load-holding valves of energy-efficient electro-hydraulic systems. Proceedings. doi: 10.3390/IeCAT2020-08478. Full text in Research Archive Show summary

  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 improved greatly the energy efficiency and motion control in comparison to state-of-the-art, valve-controlled systems typically used in mobile or offshore applications. The passive load-holding function was realized by two pilot-operated check valves placed on the cylinder ports, where their pilot pressure is selected by a dedicated on/off electro valve. 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 are disengaged to enable the piston motion using closed-loop position control. Such a sudden variation in the piston position that is triggered by switching the load-holding valves can increase up to 4 mm when open-loop position control is 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 switch the pilot-operated check valves. The proposed experimental validation of this method eliminates the piston position’s drop highlighted before and improves the motion control, mainly when operating the crane in open-loop. Theses outcomes benefit those systems where the kinematics amplifies the piston motion significantly (e.g., in aerial platforms) increasing, therefore, the operational safety.

• Hagen, Daniel; Padovani, Damiano & Choux, Martin Marie Hubert (2020). Guidelines to Select Between Self-Contained Electro-Hydraulic and Electro-Mechanical Cylinders, 15th IEEE Conference on Industrial Electronics and Applications. Institute of Electrical and Electronics Engineers (IEEE). ISSN 9781728151687. p. 547–554. doi: 10.1109/ICIEA48937.2020.9248373. Full text in Research Archive
• Hagen, Daniel; Padovani, Damiano & Choux, Martin Marie Hubert (2019). A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency. Actuators. 8(4). doi: 10.3390/ACT8040078. Full text in Research Archive
• Hagen, Daniel; Padovani, Damiano & Choux, Martin Marie Hubert (2019). A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 1: Motion Control. Actuators. 8(4). doi: 10.3390/ACT8040079. Full text in Research Archive
• Hagen, Daniel; Padovani, Damiano & Choux, Martin Marie Hubert (2019). Design and Implementation of Pressure Feedback for Load-Carrying Applications with Position Control. In Huhtala, Kalevi; Tikkanen, Seppo & Uusi-Heikkilä, Janne (Ed.), The Sixteenth Scandinavian International Conference on Fluid Power, SICFP19: Proceedings. Tampere University of Technology. ISSN 9789520313029. p. 520–534. Full text in Research Archive Show summary

  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 feedback 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 proposed “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.

• Hagen, Daniel; Padovani, Damiano & Choux, Martin Marie Hubert (2019). Enabling Energy Savings in Offshore Mechatronic Systems by using Self-Contained Cylinders. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. 40(2), p. 89–108. doi: 10.4173/mic.2019.2.2. Full text in Research Archive
• Padovani, Damiano; Ketelsen, Søren; Hagen, Daniel & Schmidt, Lasse (2019). A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability. Energies. 12(2). doi: 10.3390/en12020292. Full text in Research Archive
• Hagen, Daniel; Padovani, Damiano & Ebbesen, Morten Kjeld (2018). Study of a Self-Contained Electro-Hydraulic Cylinder Drive, 2018 Global Fluid Power Society PhD Symposium (GFPS). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9781538647851. doi: 10.1109/GFPS.2018.8472360. Full text in Research Archive Show summary

  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.

• Hagen, Daniel; Pawlus, Witold; Ebbesen, Morten Kjeld & Andersen, Torben Ole (2017). Feasibility Study of Electromechanical Cylinder Drivetrain for Offshore Mechatronic Systems. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. 38(2), p. 59–77. doi: 10.4173/mic.2017.2.2. Full text in Research Archive Show summary

  Currently, there is an increasing focus on the environmental impact and energy consumption of the oil and gas industry. In o shore 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 o shore vertical pipe handling machine. The scope of this paper is to investigate the feasibility of a commercial o-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 o shore 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.

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• Hagen, Daniel; Eide, Marcus; Liland, Tollak & Aftab, Muhammad Faisal (2026). Mobile Manipulator with Passive Mechanical Coupling for Autonomous Object-Handling. Full text in Research Archive
• Bergsjø, Leonora Onarheim; Hagen, Daniel & Hansen, Michael Rygaard (2025). Hva om serviceroboter blir helsepersonells nye beste venn? doi: https:/www.uia.no/om-uia/senter-og-nettverk/senter-for-e-helse/arrangementer/arendalsuka_sako.html. Full text in Research Archive
• Hagen, Daniel (2025). Rapid Model-Based Design and Real-Time Digital Twin Integration: An Offshore Robot Case Study. doi: 10.1109/isie62713.2025.11124748. Full text in Research Archive
• Hagen, Daniel (2024). UiAbot: A Versatile Autonomous Mobile Robot Platform for Research and Education. Full text in Research Archive
• Hagen, Daniel & Padovani, Damiano (2020). A method for smoothly disengaging the load-holding valves of energy-efficient electro-hydraulic systems. Full text in Research Archive
• Hagen, Daniel (2020). Guidelines to Select Between Self-Contained Electro-Hydraulic and Electro-Mechanical Cylinders. Full text in Research Archive
• Hagen, Daniel (2019). Design and Implementation of Pressure Feedback for Load-Carrying Applications with Position Control. Full text in Research Archive
• Hagen, Daniel (2019). WP 1.4 – Electrical and Electrohydraulic Linear Actuators. Full text in Research Archive
• Hagen, Daniel; Padovani, Damiano & Ebbesen, Morten Kjeld (2018). Study of a Self-Contained Electro-Hydraulic Cylinder Drive. Full text in Research Archive
• Hagen, Daniel (2018). Study of a Self-Contained Electro-Hydraulic Cylinder Drive. Full text in Research Archive
• Hagen, Daniel (2018). Study of a Self-Contained Electro-Hydraulic Cylinder Drive. Full text in Research Archive
• Hagen, Daniel (2017). Optimal Selection of Drivetrains in Offshore Mechatronic Systems. Full text in Research Archive
• Hagen, Daniel (2020). Improving Energy Efficiency and Motion Control in Load-Carrying Applications using Self-Contained Cylinders. Universitetet i Agder. ISSN 9788271179854. Full text in Research Archive Show summary

  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.

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