Shiphandling Simulation Application to Waterway Design (1992) / Chapter Skim
Currently Skimming:
4. Shiphandling Simulators
4. Shiphandling Simulators
Pages 31-42
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 31... ...
The primary contribution of simulation is quantitative performance data characterizing the design and operational alternatives being considered. A number of methods furnish data that can be used in the design process: physical models, fast-time mathematical models, and man-in-the-loop simulation.
|
From page 32... ...
, processing of these data, and developing the visual scene are emerging as the dominant costs in marine simulation. COMPUTER-BASED MODEL FOR SHIP BEHAVIOR A simulation model for ship behavior is a computer-resident mathematical model of the waterway and of the dynamic properties of the ship.
|
From page 33... ...
as datum, generates simple rudder and engine commands as specified by the associated transit strategy in an attempt to minimize any deviation between the current location and Me prescribed Back. The simulation obtained by simple pilot models are useful because dynamically feasible swept paths can be defined.
|
From page 34... ...
Although the measures for representing human behavior introduce some variability into the pilot model, they do not achieve any semblance of the full complexity of human pilot behavior that reflects many different styles and levels of effectiveness in shiphandling. To represent the underlying perceptual and cognitive processes involved in detecting and interpreting aids to navigation and vessel traffic, decisions about maneuvering actions, and other operational decisions, much more sophisticated pilot models than exist today would be needed.
|
From page 35... ...
or an array of screens presenting the pilot with a rendering of an actual 180° or a full 360° view. When using these displays, the following interdependent physical factors limit perceived realism: display size, physical field of view, viewing distance (from the eye)
|
From page 36... ...
Docking simulators generally require a larger vertical field than those applied to maneuvering or channel design work. Reasonable depth perception and reduction of parallax error for the simulation scene in relation to a simulator's bridge typically require a screen-to-eye distance greater than 10 feet.
|
From page 37... ...
Because the update rate varies inversely with the number and type of objects arrayed in the three-dimensional space that will be visible or bounded within the scene, simple scenes can be updated at a faster rate than complicated scenes. An elemental shape formed in the perspective view (e.g., a polygon representing a buoy)
|
From page 38... ...
Consequently, no consensus exists among simulation practitioners regarding what levels of fidelity are required to achieve reliable simulation outcomes, or how the requirement might vary with the simulation study objectives. There is considerable interest in the potential of technical representaiions such as electronic charts and real-time positioning displays to substantially augment and perhaps become more important than visual observations.
|
From page 39... ...
Because pilots are integral to shiphandling in confined waterways, inclusion of pilots with knowledge of the design vessel, local conditions, and tug assistance is essential to the simulation process, if the simulation is to have complete credibility with prospective users of the waterway. The pilot views the waterway scene from the bridge directly or, especially in the case of obscured vision, through electronic means including VIIF communications, radar, and electronic aids to navigation.
|
From page 40... ...
It is difficult to evaluate whether or not pilots chosen to participate in a given simulation reflect the average capabilities of local pilots or how their performance may have been affected by simulation conditions or the pilots' sophistication with simulation techniques. LEVEL OF SIMULATION Each simulation facility conducting port and waterway design work uses different simulator components.
|
From page 41... ...
41 o · ~ ca o .e ~ - ~ a: c, - ~ ~~ ca)
|
From page 42... ...
, environmental conditions, and appropriate simulator hardware are selected and installed, the simulation process occurs in three steps. In the preliminary phase, mathematical models of each simulation component are collected, and the various constants are identified (see Chapter 5~.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.