Training simulator for cutter suction dredgers

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Bridge of the cutter dredger with outside view
Generally speaking, dredgers are increasingly equipped with intelligent sensors, digital process visualisation and smart control systems. To be able to make immediate optimum use of these systems, it is essential that instruction be provided in advance. Acquiring experience through trial and error, however, costs time and money. Ever younger crews, the increased advances in automated vessels and alterations to leave times have meant that the demand for training has risen. Training people in understanding the dredging process and the optimal deployment of the operating system in the shortest possible time is reason for dredging contractors to switch to training simulators. Another advantage of simulators is that they enable skills to be developed, without generating any risk to the environment or the process. Training simulators have in fact already been in use in the dredging industry, for a number of years.

Trainer Settings
Thanks to the increase in computing power of modern computers, it is now possible to develop training simulators, at an acceptable cost, which accurately simulate the real life situation. For Société de Dragage International S.A. (SDI), the French subsidiary of Dredging, Environment and Maritime Engineering N.V. (DEME), a training simulator has been developed for cutter suction dredgers.
This simulator makes it possible to select a range of different ship configurations. On each vessel, a range of anchors, cutters and pump impellers can be chosen. In this way, the behaviour of a range of vessels can be experienced in the same environment. The trainer is able to introduce disruptions to the process, which must then be identified and solved by the trainee. In this way, without placing the dredging vessel at risk, it is possible to train for situations, and to repeat the programme, until the problems are adequately solved.

Simulator layout
To give the trainee the feeling of working on a real cutter suction dredger, the noise of diesel engines, winches and cutter have been added. These noises are linked to real-time process events. The acceleration of a side winch, for example, generates the accompanying noise. Vibrations such as those actually felt in reality, are also generated. For this purpose, a 'floor shaker' has been mounted beneath the floor on which the trainee's seat is installed. In this way, vibrations generated by the diesels or the cutter can be transferred to the operator's seat. This includes the heavy vibrations experienced for example when cutting rock. Finally, the outside view from the trainee's position is also simulated. With a viewing angle of 120 degrees forwards, the outside world is displayed, with a view of the anchor booms, side winches, ladder winch and steel cables.
The dredger console is identical to the console mounted on board, but without the navigation section. The automated systems are also identical to those on the new cutter suction dredger, but again are restricted to the dredging process alone. In other words, the complete simulator consists of 4 components:

the replacement for the actual physical cutter suction dredger: the dredge process simulator
an operating console, identical to that mounted on board
automated processes based on computer programs in PLCs and PCs, as also actually installed on board
a presentation of the environment in order to provide audio-visual information, giving the trainee the impression of actually being on board.

Dredge Process simulator
The basis for the training simulator is the dynamic behaviour of the cutter suction dredging process, which must be controlled. This process must therefore also be simulated on the basis of mathematical models. With this in mind, the process has been hierarchically broken down into the following
sub-processes:

movement models, including barge, ladder, cutter head, main spud with spud carrier, auxiliary spud, anchor booms and anchors (including the accompanying motors and hydraulic drive systems)
excavation model for the interaction between cutter head and soil to be excavated
mixture transport for the discharge of the excavated soil
power supply, consisting of diesels and simulated power management systems
environmental model for simulating the caving in of the soil, the influence of water movements (tide, current, wave motion)
auxiliary systems, for example for such as for hydraulics, gland water, flushing and jet systems.

Overview of the dredge process at the trainer's desk
For the most part, these systems consist of standard components such as motors (electrical and hydraulic), diesel engines, pumps, valves, pipes and wires. Using the above systems, all the essential functions of the actual ship are mathematically simulated.
This means that all necessary controls and operations required in reality are delivered to these mathematical models, so that the dynamic response is simulated in accordance with the actual behaviour, in practice.
In other words, the process simulator imitates the behaviour of the actual vessel. The behaviour of the automated systems and actions by the operator are not simulated. Instead, they are actually implemented by the automated system linked to the simulation process, and by the trainee operator.

Interaction with the environment
The excavation of the soil and the caving-in behaviour of various soil types is a key component of the training simulator. For the excavation model, a simplified version of the complex model in use at MTI was designed by the MTI centre. The model has been simplified such that although the behaviour remains present, the precise result is not simulated, saving on computing time. Soil caving-in behaviour, dependent on soil type, has been added to the excavation model.
As a consequence, just as in reality, soil will cave in at points where excavation has been carried out. If not all cut-away soil is sucked up, spillage occurs. The level of spillage is recorded in the caving-in model. Whenever during the return swing, the soil is once again cut away, the trainee will note that a lower torque is required, whilst production levels are maintained.

Training
The training manual produced specifically by MTI/TID and DEME for the training simulator forms the basis for the training programme. The training programme has been designed for employees of different skill levels, enabling them all to broaden and deepen their knowledge.

Conclusion
This cutter simulator was developed by IHC Systems on behalf of DEME. In this process, above all in respect of the layout of the various mathematical dynamic models required, DEME submitted a great deal of process knowledge, and validated the results. The MTI developed a detailed model for the cutting forces, which responds dynamically and in real-time to changing soil types and soil composition. In collaboration with DEME, the Training Institute for Dredging (TID) developed teaching material, to enable the crew to be effectively trained using this simulator. Training includes learning to work with cutter suction dredgers and the optimum deployment of the automated systems.
By adding an outside view, including noise and a 'floor shaker', valuable information is delivered from the environment, which is important in recognising undesired process situations, approaching danger or threatening disasters.
The simulator was successfully commissioned in September 2005, under DEME's motto; "There's no substitute for (simulated) experience"

(Source : P&D nr. 164 from 2005)