Platoon running control system

A platoon running control system which is able to recognize the position of a vehicle within a platoon and to appropriately respond to a change, for example, when another vehicle leaving the platoon. If the vehicle is not in a platoon running mode, a communication control ECU assigns an ID = 1 to the vehicle, and a vehicle control ECU operates the vehicle in an auto-drive mode based on a signal such as from a magnetic sensor or a CCD camera. During platoon-running mode, a light receiver receives data including ID information from a preceding vehicle, and the controlled vehicle is assigned an ID according to a rule in which the ID of the vehicle = ID of the preceding vehicle + 1. Then, the vehicle starts platoon running using data from the preceding vehicle. When the system received information that the preceding vehicle will leave the platoon, platoon-leaving data is transmitted to the vehicle, which then transmits such data to the following vehicle. The vehicle changes its ID to 1 when it does not receive any more data from the preceding vehicle. In a case where its ID has been changed to 1 from 3 or greater, the vehicle accelerates so as to re-form the platoon.