| 摘要 |
PURPOSE:To display as much information on the travel direction of a vehicle as possible within a limited display screen by showing a vehicle position on the periphery of a certain ellipse positioned approximately at the center of the screen, in a direction toward the center of the ellipse. CONSTITUTION:CPU finds the current coordinate positions (x), (y) and (z) of a vehicle, and the current bearing theta thereof through a vehicle position recognition section during a travel. Then, an angle of 180 degrees is added to the bearing theta to give the rear bearing alpha of the vehicle. Thereafter, an ellipse with the prescribed values of major and minor axes is assumed on a screen, and peripheral positions xa, ya and za viewed from the origin of the ellipse are obtained by using an expression xa<2>/a<2>+ya<2>/b=1 where y1=x1tan alpha. Coordinates xo and yo resulting from the subtraction of the values xa and ya so obtained from the current position of the vehicle are used to show the center of the screen. Consequently, the display of the vehicle on the screen is always positioned on the ellipse and directed toward the center of the screen. |
