2.3.3 Mounted Device
In MME system, the positioning system of eyepoints should be required. It is often to use magnetism position and bearing system for virtual reality system according to the high accuracy and responsibility, but it has shortcomings such as the small coverage (one transmitter covers the area of which radius is 1.5 meters, so we need more than 4 transmitters for typical sized bridge mockup; 6 meters X 6 meters) and data transmission is wired. The latter one will be cleared easily by using radio data communication system.
The positioning system is very important to utilize MME system, and the performance of MME system is dependent on accuracy and responsibility. Roughly speaking according to our investigation,, requirements of these performances are 1 mm for position accuracy and higher than 20 Hz for responsibility.
MME system needs eyepoints positioning and separation visual system that means to separate visual images on the same screen for each other.
There are two methods to separate images at different eyepoints, one is a time sharing system and the other is a polarization system. These systems are not useful for human operation to mount on body, but it is necessary to do in the update technology.
So it will be better when the load such as the weight of glass, etc. is smaller. Because of this reason, we should take the polarization system, but this system will be able to provide only two channels at once. This is not enough for bridge team training and/or survey.
Here the time sharing system will be adapted to separate visual system. The performance required for the time sharing system will be discussed later on.
2.3.4 Computing System
Typical computing system in Ship-handling Simulator consists of 3D visual calculation, maneuvering, control of navigation instrument and controller. Here, we will focus discussion on the 3D visual calculation, and illustrate as flow-chart in Fig.8.
We propose the new algorism of Visual system for Ship-handling simulator, pseudo-position system mentioned above and image correction system.
Here we design the mockup for the containership as the example of the conventional vessel using pseudo-position system, introduce image correction system and time sharing system.
Fig.8 Flowchart on MME system
(1) Pseudo-position System
The concept of this system is described above, hereby the actual example is presented using Container ship.
○ Her width is approximately 25 meters, and
○ her wheel house's is width 15 meters.
○ Simulator space is where it is able to set cylindrical screen of which radius is 7 meters.
We can make a space for 6 meters width wheel house and 2 meters width wing, and the rest space or the minimum distance from wing to the screen will be 2 meters. In case of wing operation, the screen distance is only 2 meters, but in case of normal operation it is 7 meters. The difference of screen distance affects the brightness of image, but we can adjust this problem using image correction system mentioned later on.
So the relationship between real bridge and mockup size is as follows.
○ Wheel house zone is 6 meter width.
○ Jump zone is between 3 meters and 10.5 meters which are real scale,
If the person moves through Jump zone that is the connection between wheel house and wing on the simulator, the image jumps from the point at the distance 3 meters from center of bridge to the point at the distance 10.5 meters.
(2) Image Correction system
Not only the distortion of image but also the brightness is effected when the person moves in the bridge. MME system is able to get the eyepoints position, so we can correct not only distortion of image but also the screen brightness.
Image distortion will be able to be corrected to calculate by 3DCG using eyepoints, and screen brightness is affected by the distance between eyepoints and the point of screen, and by the screen reflection characteristics.
The screen reflection characteristics are affected by the type and by the materials of the screen, and the distortion will be described by next equation.
We are able to calculate θ and Γ from the position of eyepoints Pe, and screen reflection characteristics Φ(θ) shown as example in Fig.5 are described by LUT (Look up Table) in calculation. We can correct brightness dividing by calculated reflection characteristics D(Pe,φe).
(3) Synthesizing system
Supporting views for plural members' eyepoints, typically we use the time-sharing system. The time-sharing system is operated so that the views are drowning each one frame.
If the numbers of members are 4 persons, then we divide 4 times. Refreshment is required higher than 20 Hz according to our investigation, then we need the computer performance that the images can be drawn 2O X 4 = 80Hz.
It should be confirmed that the projection system have high-speed performance and the reminder of brightness, so we choose the projection system that has a higher performance.
We studied the basic performance of MME system in former paper,, and we got the fruitful conclusion for MME system. In the case of fixed eyepoint system with small distance, there is a problem that it is easy to grasp relative motion because of finding the pixel motion according to the image resolution, but we got a conclusion that it was very useful to use the movable eyepoint system for resolving former problem.
In this paper, we proposed a new system MME system including pseudo-position system and image correction system which will be able to make a good reality in visual scene not only to correct image distortion, but also to correct the brightness of images. Also we had an example of design to establish a new system, there are some future problems, one of which is load of operator according to taking glass of time sharing, etc., but we certainly believe that MME system will contribute for simulator training and/or research in near future.
 Susumu Toya, Hiroaki Kobayashi and Syoichi Senda, "Basic Study on Analysis of the Function in Bridge Team", Proceedings in 11th INSLC, pp.139-146, 2000
 Yasuo Arai, Hiroaki Kobayashi, Makoto Endo, Masanori Endo, Hiroyuki Mizuno, Shiro Arai, Masanori Tsugane, Syoichi Senda, Shin Murata and Tomoki Oku, "A Study on the Systematic Validation of Ship-Handling Simulator's Function Corresponding Nautical Missions", Conference Proceedings MARSIM2000, pp.97-112, 2000
 Masaki Umatani and N. Kohguchi, "On Distance Cognition and Its Learning Effect on the Sea and Bridge Simulator", The Journal of Japan Institute of Navigation, Vol.104, ISSN 0388-7405, pp.47-54, 2001
 Yasuo Arai, Taro Minamiya and Shigeyuki Okuda, "Basic Study on the 3D Visual System for Multiple Eye Points", The Journal of Japan Institute of Navigation, Vol.107, ISSN 0388-7405, pp.55-60, 2002
 Yasuo Arai, Taro Minamiya and Shigeyuki Okuda, "Basic Study on the 3D Visual System for Multiple Eye Points", The proceedings of INSLC12 (CD), 2002
 Masatoshi Endo, "Survey of New Technology and its Application on Ship Maneuvering Simulators", NAVIGATION, Vol.150, ISSN 0919-9985, pp.33-38, 2001
 Hiroaki Kobayashi and Akiko Uchino, "On the Human Characteristics Concerning Visual Information", The Journal of Japan Institute of Navigation, Vol.91, ISSN 0388-7405, pp.255-261, 1994
Yasuo ARAI graduated from the Faculty of Engineering, Osaka University in 1969, and holds a Bachelor's degree (Engineering). He is a professor of Marine Technical College. He is a director of Japan Institute of Navigation, a vice chairman (Area Representative of Asia and Pacific Ocean) of International Marine Simulator Forum, a member of Ship Handling Simulator Research Committee of Japan Institute of Navigation, the Society of Naval Architects of Japan, and the Institute of Electronics, Information and Communication Engineers. His major fields are Marine Education and Training, radio navigational aids, nautical instruments and simulation technology