Simulated Voyages Using Simulation Technology to Train and License Mariners (1996) / Chapter Skim
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7 Simulation and Simulator Validity and Validation
7 Simulation and Simulator Validity and Validation
Pages 158-172
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From page 158... ...
As a result, some simulator facilities use either a number of models to meet the specific application needs of training sponsors or adjust their models to simulate a different type or size vessel. If these adjustments are not correct, the resulting trajectory predictions will be inaccurate, regardless of the quality of the algorithms used to generate them or the apparent validity of the simulation.
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From page 159... ...
The accuracy of trajectory prediction models available to drive a simulation can be compared with the level of fidelity specified by the training analysis as necessary to achieve training objectives. The accuracy of trajectory prediction, for instance, is less important in courses where vessel maneuvering behavior is not an instructional objective than in courses where maneuvering is required to achieve the goal of certain learning situations or is the primary instructional objective.
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From page 160... ...
To build and improve confidence among mariners, training sponsors, and marine licensing authorities, there are strong pressures to use the highest level of realism possible. Nevertheless, it is possible to alter the mathematical trajectory prediction models to accentuate certain vessel maneuvering behavior, for example, as an instructional technique to assist a trainee in becoming aware of this behavior.
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From page 161... ...
It is generally assumed that the database is technically advanced enough to give accurate simulations of ship maneuvers in deep and unrestricted waters. The simulation of ship dynamics for shallow-water effects, anchoring evolutions, and ship-to-ship interactions are less technically advanced.
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From page 162... ...
If procedures could be developed to allow the public access to existing proprietary data without disclosing the source, simulation design might be significantly improved with a minimum investment. Manned Models Physical models provide a simple approach to training in the understanding and application of the hydrodynamics of ship motion in deep water and close-in operations, including docking and coming alongside, maneuvering in shallow water and near banks, and in ship-to-ship operations.
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From page 163... ...
CURRENT PRACTICE IN VALIDATION As noted in Chapter 2, commercial air carrier simulators are evaluated and validated at a particular level, depending on their application, for a range of operating conditions. Generally, a commercial air carrier simulator represents a particular aircraft model with a cockpit arrangement specified by the operator.
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From page 164... ...
This process continues on an iterative basis until the test mariners are satisfied, or until the operations personnel indicate that no more changes can be accommodated. This iterative model validation process represents the state of practice in the industry, but it is not endorsed by the committee.
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From page 165... ...
There may be several reasons why a facility operator makes field adjustments in the mathematical models. First, in using the model there may be anecdotal indications that the accuracy and fidelity of the maneuvering behavior are different from those needed to achieve training objectives.
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From page 166... ...
To teach basic shiphandling in deep-water operating conditions, moderately accurate ship hydrodynamic models may be adequate. High accuracy and fidelity in hydrodynamic, channel, and harbor models are important for shiphandling training for conditions of shallow water, confined water, and small underkeel clearances.
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From page 167... ...
If manned models are used for licensing assessment, validation will be needed to ensure that models produce faithful vessel behavior. Objective and Subjective Validation The approach to validation of marine simulators or simulations might follow the commercial air carrier industry's approach of including objective with subjective evaluation.
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From page 168... ...
An Approach to Validation of Ad Hoc Models and Modifications There are strong reasons to discourage ad hoc creation or field adjustments of mathematical models using software within some simulators because field adjustments almost invariably introduce uncertainties and unanticipated inaccuracies. The commercial air carrier industry requires that all modifications to a simulation be documented and that the simulator be re-evaluated after modifications are made.
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From page 169... ...
For simulator and simulation standards, there are numerous parties at interest, including facility operators, shipping companies, unions, pilot associations, port authorities, regulators, maritime academies, training schools, and the mariners themselves. To be effectively implemented, the simulator and simulation standards must be based on a consensus view.
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From page 170... ...
Currently, simulations are initially validated by the manufacturer, then validated by the facility operator through use of subjective "test mariners." Often, facility operators continue to periodically modify simulations after the initial validation. This practice of continually modifying simulations can result in inconsistent training programs, as successive classes may be conducted with different simulations.
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From page 171... ...
An approach to simulator and simulation validation might follow the commercial air carrier industry process, which relies on both objective and subjective validation. The objective validations could include development of a "realism rating" based on an assessment of factors such as image portrayal and predicted ship trajectories.
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From page 172... ...
172 SIMULATED VOYAGES Hays, R.T., and M.J. Singer.
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