Hino Motors Ltd unveiled a monitor system for trucks to display a bird's eye view of the vehicle in color, as well as its surroundings, captured with four identical cameras.
The system was demonstrated at the 40th Tokyo Motor Show, which is open to the public from Oct 27 to Nov 11, 2007.
The monitor normally displays an image shot with three cameras mounted on the front and both sides of the vehicle. When the driver puts the shift lever in reverse, the image on the screen is switched over to the one shot with the cameras on the rear and both sides.
The display screen is divided into three areas. When an object moves in any of these areas, the system warns the driver by causing that area to blink in red or by sounding an alarm. Schedule for product launch has yet to be decided.
The system employs CCD cameras that have a high resolution of about 3 Mpixels, frame rate of 30fps and viewing angle of 140°. The front and rear cameras both cover the display range of about 5m, while the range covered by each of the side cameras is about 2.5m.
Based on the images supplied from the side cameras, the system "can determine the distance with an error within about 10cm," said a demonstrator from Hino Motors. The electronic control unit (ECU) provided for image processing is a product manufactured by Denso Corp.
Hino Motors' system is equipped with an algorithm used for detecting the movement of an object. This algorithm prevents the erroneous detection of stationary object by factoring in the relative speed between the vehicle and the object.
But there are still many problems to be tackled. For example, the system will "erroneously respond to a tree if it is being blown strongly in the wind," the demonstrator said.
Another major challenge is to simplify distance calibration depending on the mounting position of the camera. At present, the distance calibration is performed based on a white line drawn at a certain distance from the vehicle.
Compared with the case of cars, trucks have a wider variation in camera mounting position because a truck usually has many derivatives provided with accessories that differ from model to model. Therefore, cost-effectiveness is reduced if calibration is performed using the reference line at the time of production.