From the magazine – Royal IHC envisions a future where dredging vessels can operate largely autonomously and remotely from the shore. The development of “assisted autonomy” for hopper dredgers is already underway, where the system takes control of certain operations under human supervision.
This article originally appeared SWZ|Maritime’s February 2024 dredging special. It was written by Jeroen Peters, manager Engineering Systems at Royal IHC, jdpa.peters@royalihc.com, and Jacco Osnabrugge, manager R&D Systems at Royal IHC, j.osnabrugge@royalihc.com.
The maritime industry is seeing a trend towards increased autonomy and application of decision support systems in vessel operations. It is a trend that can provide a solution to the crew shortage. It also offers the opportunity to further improve efficiency and safety on board.
Currently, many developments in the maritime industry focus on taking over control of the vessel from the human crew, and making ships increasingly autonomous. As there is a wide variety of ship types and operations, the development of maritime autonomy has a broad spectrum.
At the moment, substantial focus is directed towards ships that are used to perform a dangerous, dull or dirty task because it is expected that these applications will provide the best business case on the short term. Examples of ships that do these kinds of tasks are autonomous minesweepers, survey vessels, ferries and tugs.
Alongside the industry organisations such as IMO, IMCA and classification societies are paving the way for rules and legislation.
Drivers for autonomous ships: safety and seafarer supply
A main driver for autonomous ships is an increase of safety, an estimated 75 to 96 per cent of marine casualties is attributed to human error (Rothblum, 2000). It is expected that the number of accidents is decreased when autonomous control is introduced.
Another driver is related to the supply of seafarers, a study predicts that there will be a shortfall in maritime officers by 2026 (BIMCO and ICS, 2021). When certain tasks can be performed from shore, this will enable mariners to perform their job closer to home, possibly making the job of maritime officer appealing to more people.
Autonomous vessels could therefore partly be a solution to close the gap between seafarer supply and demand. When tasks need to be performed that require focus for longer periods of time or processing of large amounts of information, autonomous and decision support systems are deemed to provide a higher operational consistency and efficiency.
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Evolution of dredging automation
The development of advanced dredging and sailing automation systems for hopper dredgers made significant steps in the last decades. In the early 1990s, the first integrated dredging control systems (DCSs) were developed and implemented on board by Royal IHC, allowing for centralised control of the dredging process from a single desk.
Subsequently, in the later part of the 1990s, dynamic positioning and dynamic tracking (DPDT) systems were introduced to automatically control the vessel’s position and speed with high accuracy during dredging, adapting for trail forces and large draught variations (IHC Systems 1996).
In 2006, the one-man operated bridge was introduced, making it possible for both the sailing and dredging process of the hopper dredger to be controlled by one person (IHC Holland 2007).
In the following years, artificial intelligence (AI) based automation systems were introduced for optimising the dredging process (Osnabrugge et al. 2013 and Mourik et al. 2015). Featuring an adaptive and integrated control approach of the dredging process increasing the loading production during dredging up to fifteen per cent, while at the same time reducing the fuel consumption per m3 dredging production by a similar number.
In 2018, Royal IHC started the development of a high-level control system, called “Mission Master”, to further increase the level of autonomy and efficiency of hopper dredgers.
Assisted autonomy with the Mission Master
The Mission Master works closely with different automation systems for both the sailing and dredging processes of a hopper dredger to achieve a semi-autonomous workflow. It is integrated with Royal IHC’s in-house developed automation systems, such as the DPDT System, which controls the propulsion and thrusters, and the DCS with dredging assist functionalities for controlling all the dredge equipment.
Furthermore, it is integrated with path planning and collision avoidance technology. The figure above gives a system overview of the Mission Master.
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Mission Master’s operational framework
The Mission Master operates at automation level A2 – Human delegated, as per Bureau Veritas Guidelines for Autonomous Shipping (October 2019). This means that the system performs actions, but a supervisor remains on board to confirm decisions.
The supervisor interacts with the Mission Master through a human-machine interface (HMI), which displays all important vessel and project parameters. The HMI also provides a chart view of the working area with the Mission Master’s decisions and intentions. The supervisor can confirm or reject decisions and take over manual operation at any time.
Advice from the system, such as dredge paths, can be easily modified and settings can be customised to the specific desires of the supervisor. The figure shows an example of the Mission Master HMI.
DCS with Dredging Assist
The Mission Master executes the mission by assigning dredging tasks to the DCS. These tasks include lifting the suction pipes out of the saddles, moving the gantries overboard, lowering the suction pipes and placing the drag head at the sea bottom.
During the execution of these tasks, the required dredge and jet pumps are activated while taking care of the desired valve configuration and auxiliaries. All these tasks are executed fully autonomously, but the critical tasks must first be approved by the supervisor before execution starts.
During the dredging process, automatic controllers such as dredge pump, drag head visor and loading control are activated. Feedback is provided to the Mission Master regarding the equipment’s state. Information is utilised to control the drag head’s position relative to the seabed height using the winches.
The approach for the unloading functionality is similar to the dredging functionality, providing autonomous ability to unload soil through the bottom doors, the rainbow nozzle, or a connected hose. Currently, only autonomous unloading through the bottom doors has been developed.
The system controls the bottom doors, jet pumps and jet valves in predefined sequence(s). Approval of the supervisor is requested for starting and for proceeding through the different stages. The system determines when the hopper is empty and initiates ending the sequence accordingly upon approval. At the end of the sequence, the equipment is automatically set ready for transit.
Because the supervisor can take over manual operation at any time, special attention is given to seamless transition between autonomous control and manual operation and vice versa. This requires the system to recognise all the process states of the dredge equipment accurately, also in manual control in order to get a smooth transition to automatic control.
Also read: SWZ|Maritime’s February 2024 issue: Dredging, a strategic industry
DPDT
In parallel with the dredging tasks, the Mission Master executes the mission by also assigning sailing tasks to the DPDT system. Mission Master DPDT tasks include transits to and from dredge and disposal areas, following the dredge and disposal paths calculated by the dredge path planner.
During the transits, feedback is provided regarding the status of the task, such as the estimated time of arrival at the dredge or disposal area. To execute the transits, a feasible route is generated, which is then translated into waypoints for the DPDT system. Speed set-points are commanded to control the desired vessel’s speed at the desired location in accordance with the dredging process.
Dredge path planner
Dredge path planning software has been developed, allowing the hopper dredger to optimise for dredging production and fuel consumption. During mission planning, the system calculates optimal dredge and disposal paths within the allocated area, taking into account weather conditions such as current, waves, and wind.
Measurements related to dredging production are stored specifically linked to the drag head’s position. This incorporation allows the inclusion of previous dredge cycle information in the dredge path planner. With each dredge cycle, more information becomes available, further optimising the dredge path planning.
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Collision avoidance
A collision avoidance module, utilising AIS, radar and vision sensors, incorporates the functionality to adjust the planned route to ensure compliance with the Convention on the International Regulations for Preventing Collisions at Sea (COLREGs) or local regulations.
Also taking into account the manoeuvrability of the vessel affected by hopper load and environmental forces. The initial implementation will be an advisory system to validate that the planned routes are realistic and in accordance with regulations. In a next version, the collision avoidance rerouting waypoints are interfaced to the DPDT system where it can be executed after supervisor approval.
Enhancing functionality and user experience
The Mission Master has been tested on a full mission hopper dredger simulator to identify any potential issues that may arise when installed on board a real vessel, see the picture above.
Simulating the complete mission in a realistic operational environment allows for verification and testing of the Mission Master’s proper functionality across various scenarios. The simulator has proven to be a valuable tool in the design process of the Mission Master, as the ability to comprehensively test interacting systems has already resulted in numerous design improvements.
Additionally, the user experience of the system can be evaluated and finetuned. Feedback from skippers and supervisors is gathered to determine necessary feature additions or modifications. The goal is to deploy and start testing and validating the Mission Master on a real hopper dredger soon.
Picture (top): The Mission Master tested on a full mission hopper dredger simulator (all pictures by Royal IHC).
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References
- BIMCO, ICS (2021), Seafarer Workforce Report, The global supply and demand for seafarers in 2021
- IHC Holland (2007), “One-Man-Operated Bridge”, Ports and Dredging, Vol. 167, 14-21
- IHC Systems (1996), “IHC Systems and LIPS supply a new integrated Dynamic Track Keeping system on the Pearl River”, Offshore Visie, Vol. 13, No. 3, 18-19
- Mourik R. and Osnabrugge J. (2015), “Expected future applications of artificial intelligence on dredgers”, Proceedings of the Western Dredging Association and Texas A&M University Center for Dredging Studies, Dredging Summit and Expo 2015, Houston, USA
- Osnabrugge J. and van den Bergh P.M. (2013), “Optimising manpower and reducing fuel consumption while increasing dredging production”, Conference Proceedings WODCON XX, Brussels, Belgium
- Rothblum A.M. (2000), Human Error and Marine Safety, Maritime Human Factors Conference 2000, Linthicum, USA, 2000
