Mapping road edges; collision avoidance

To map a road during travel, a vehicle has two data acquisition modules arranged on sides of the vehicle. Each includes a differential GPS (DGPS) receiver and antenna for enabling the vehicle's position to be determined and a linear camera which provides vertical one-dimensional images of an area on the respective side in a vertical plane perpendicular to the road such that information about the road is obtained from a view in a direction perpendicular to the road. A processor unit forms a map database of the road by correlating the vehicle's position and the information about the road. Instead of or in addition to the linear cameras, scanning laser radars are provided and transmit waves downward in a plane perpendicular to the road and receive reflected waves to provide information about distance between the laser radars and the ground for use in forming the database. The database is then used in a collision avoidance system. Equipped vehicles use the database in combination with a DGPS receiver to determine their position and velocity relative to the road. This is broadcast to other vehicles in the area, which compare the received position with their own position and velocity to give a warning of an imminent collision. The database may also include lane markings and road intersection information such as the edges of intersecting roads; this is used to prevent collisions at junctions. Traffic lights may transmit a signal warning of red lights. The GPS system may be supplemented by INS, video cameras, multiple local impulse transmitters, radar reflectors etc. A fully automated traffic control system is also envisaged.