Malte von Benzon

Aalborg University

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Co-Authors

Fredrik Fogh Sørensen

Aalborg University

Simon Pedersen

Aalborg University

Jesper Liniger

Aalborg University

C. Maï

Aalborg University

Sigurd Klemmensen

Aalborg University

Kenneth Schmidt

Aalborg University

Jérôme Jouffroy

University of Southern Denmark

Morten Eggert Nielsen

Aalborg University

Rasmus Olsen

Energinet (Denmark)

Mathias Marley

Norwegian University of Science and Technology

Cooperative Institutions

Aalborg University

University of Southern Denmark

Norwegian University of Science and Technology

Technische Universität Ilmenau

University College Lillebaelt

Maersk (Denmark)

Ifremer

Centre Hospitalier Intercommunal Toulon-La Seyne-sur-Mer

Université Savoie Mont Blanc

Renewable Energy Systems (United Kingdom)

Author Statistics

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Experimental Filter Comparison of an Acoustic Positioning System for Unmanned Underwater Navigation

IFAC-PapersOnLine (2022)

Fredrik Fogh Sørensen Malte von Benzon Simon Pedersen Jesper Liniger Kenneth Schmidt

The demand for Unmanned Underwater Vehicles (UUVs) for various operations has increased. Automating these operations requires good knowledge of the location of the UUV. This study investigates the filter lag in the commercial low-cost Underwater GPS Explorer Kit, a short baseline (SBL) from Water Linked. Furthermore, different filters are designed in an attempt to minimize the filter lag. Minimizing the lag is beneficial for real-time navigation, as delays have a negative impact on stability. Three different filters are designed; a model-free simple moving average (SMA) filter, a Kalman filter (KF) based on a constant velocity motion model, and lastly, an unscented Kalman filter (UKF) based on the non-linear model derived from the robot's dynamics. A large filter lag is found in the original filter; however, it can be concluded that a model-based filter with knowledge of the system dynamics can be used for minimizing the filter lag.

Phase lag

10.1016/j.ifacol.2022.11.328

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Citations (2)

Internal Model Control for AUVs with Output Time Delays and Input Disturbances

IFAC-PapersOnLine (2023)

Simon Pedersen Jesper Liniger Fredrik Fogh Sørensen Malte von Benzon Morten Eggert Nielsen

Autonomous Underwater Vehicles (AUVs) are increasingly being used for offshore inspection tasks. This paper investigates how navigation using Simple Internal Model Control for Proportional-Integral-Derivative Control (SIMC-PID) operates in a realistic offshore environment with waves and ocean current acting as input disturbances while the available underwater sensors introduce time delays on the output signals. First, the time delays are determined by investigating available absolute positioning sensor systems. Then, a model of the AUV and the external disturbances is established. The model-based SIMC-PID controller is tuned and examined based on acceptable disturbance rejection while tolerating the dominant time delays. Two simulation case studies show that the heave controller, in both cases, struggles to stabilize in 0 to 8 meters depths, while the surge and sway controllers tolerate the Doppler Velocity Log case (DVL) acceptably. Short Baseline (SBL) shows unacceptable performance in 0 to 15 meters depths. It is concluded that the simplicity of the SIMC-PID controller is an advantage and, therefore, useful when time delays are relatively small, but more advanced techniques must be applied for larger delays such as those introduced by SBL systems.

Internal model

Dynamic positioning

10.1016/j.ifacol.2023.10.375

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COALA - A Novel Approach to Offshore Tubular Inspection and Cleaning

Sigurd Klemmensen Rasmus Olsen Kristian Turner Fredrik Fogh Sørensen Malte von Benzon

Marine growth is a significant challenge in the offshore industry, as it contributes to increased wave fatigue on assets, especially small members such as risers, and conductors that transport oil and gas, are vulnerable to the effects of marine growth. Standard solutions used to clean marine growth are time-consuming and highly operator-dependent. This work aims to develop a solution for cleaning and inspection that will increase operational efficiency. Based on a series of design criteria, a new solution called COALA is designed and built. First, it was tested in a controlled environment at SubC Partner, and after redesigning based on the fast prototype, it was deployed for an offshore validation campaign. This campaign was conducted to obtain learnings from an operational environment to further improve the design. From the operational environment test, it was shown that the COALA is approximately 70 % more efficient in cleaning off marine growth compared to standard ROV solutions. It was also found that the COALA is able to inspect the member by performing one pass of a member. The COALA obtains a Technology Readiness Level of 6, meaning that it is tested with success in an operational environment.

Operational efficiency

10.1109/oceanslimerick52467.2023.10244571

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Citations (2)

Towards Autonomous Subsea Maintenance on Offshore Structures with Unmanned Underwater Vehicles

Simon Pedersen Jesper Liniger Malte von Benzon Fredrik Fogh Sørensen C. Maï

Subsea

Intervention AUV

10.1109/oceans51537.2024.10682312

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Stabilization of a ROV in Three-dimensional Space Using an Underwater Acoustic Positioning System

IFAC-PapersOnLine (2019)

Simon Pedersen Jesper Liniger Fredrik Fogh Sørensen Kenneth Schmidt Malte von Benzon

In subsea applications there are an increasing demand for Remotely Operated Vehicles (ROV's). This study examines a BlueROV2 inspection ROV prototype for autonomous operation in three-dimensional space. This study describes the ROV modelling, identification, control development and closed-loop simulations and experiments. The main transmitter applied for the navigation is an Underwater Acoustic Positioning System (UAPS) which acts as an underwater GPS unit. The transmitter introduces a dominant output time delay which is handled by a smith predictor. The results show that the smith predictor does not handle the time delay well, probably because the time delay is time-variant. Online identification of the time delay is proposed as a potential solution for minimizing the impact of the time delay variations over time.

Subsea

Remotely operated vehicle

Identification

Smith predictor

10.1016/j.ifacol.2019.11.037

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Citations (20)

Automatic Control of a Remotely Operated Vehicle for Shallow Water Near-Structure Operations

Malte von Benzon

10.54337/aau715854697

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Optical and Acoustic Imaging Comparison in a Controlled Underwater Environment

Fredrik Fogh Sørensen C. Maï Malte von Benzon Simon Pedersen Jesper Liniger

Accurate sensing of objects in the marine environment under varying environmental conditions can be performed using a variety of sensing modalities; acoustic methods (sonar) dominate due to the inherent high transmissivity of sound in water, but visual sensing (cameras) are also valuable tools, that are, however, more affected by turbidity and lighting. In this work, the operational limits with respect to turbidity, lightning, and target object distance, of these two main sensing modalities are compared in a controlled underwater environment, embodied by two off-the-shelf commercial products, chosen for high-measurement resolution and ease of integration, in the form of a high-frequency forward-looking imaging sonar and an infrared and color stereo camera, which is additionally assisted by a laser line reference. It is shown that the stereo camera yields high fidelity measurements up to a turbidity of 1 FTU at distances up to 1.7 m, whereafter clouding of the image renders the sensor unable to calculate object distances and dimensions. The sonar is unaffected by the additional turbidity up to the upper test limit of 6 FTU.

Stereo imaging

Turbidity

High fidelity

10.1109/oceanslimerick52467.2023.10244506

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Citations (1)

On Marine Growth Removal on Offshore Structures

OCEANS 2022 - Chennai (2022)

Simon Pedersen Jesper Liniger Fredrik Fogh Sørensen Malte von Benzon

Marine growth is a severe problem to offshore structures causing additional weight, increase in surface area, and roughness resulting in larger wave loads. Historically, the offshore Oil & Gas (O&G) industry has removed the marine growth by divers and in recent years by remotely operated vehicles (ROVs), while the offshore wind industry typically handles the problems by oversizing the structures instead of investing in cleaning campaigns. This paper describes the problems associated with marine growth to offshore structures, how it is currently being addressed by the O&G and Wind industries, respectively, and which potential solutions can be improved or introduced in the future. It is concluded that improvements within the design, automation, and instrumentation for ROVs can decrease the cost of marine growth removal substantially. It is predicted that the development of ROV technologies will drastically improve the marine growth removal processes.

Offshore construction

Marine technology

Marine industry

10.1109/oceanschennai45887.2022.9775498

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Citations (10)

Fault Tree Analysis of Sensor Technologies for Autonomous UUV Navigation

IFAC-PapersOnLine (2022)

Fredrik Fogh Sørensen Malte von Benzon Simon Pedersen Jesper Liniger C. Maï

Autonomous unmanned underwater vehicles (UUVs) are increasingly used for inspection and cleaning tasks. While automating these tasks could greatly reduce the cost, it requires reliable feedback from position and surroundings. Both internal effects and different physical properties affect sensors, resulting in inaccurate feedback if not handled correctly by the navigation system. In this study, an overview of these effects and properties are examined for the most common sensor technologies used for underwater navigation. A fault tree analysis (FTA) is conducted to get knowledge about how the sensor faults, as a result of these effects, affect automated near-structure and off-structure missions, respectively. Moreover, experiments are carried out with a high-resolution sonar and stereo camera to compare the measurement accuracy at different distances. The sensor comparing test shows that cameras can, in some cases, be insufficient to use as the only sensor for obstacle avoidance. It is concluded that the sensor criticality is case-specific; in general, especially faults on attitude feedback are severe for an acceptably-working navigation system and should therefore have high priority when selecting the robotic sensors.

Obstacle avoidance

Tree (set theory)

Position sensor

10.1016/j.ifacol.2022.10.474

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Citations (3)

Incipient Fault Analysis of Thruster Propellers from Offshore Operations

Malte von Benzon Fredrik Fogh Sørensen C. Maï Simon Pedersen Jesper Liniger

10.1109/oceans51537.2024.10682342

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