Apparatus and method for controlling speed in cooperative adaptive cruise control system

A cooperative adaptive cruise control (CACC) system that is provided in a subject vehicle to control a driving speed of the subject vehicle, comprising:

• a communication unit configured to receive vehicle information including position and driving information from neighboring vehicles using V2V (Vehicle to Vehicle) communications and to receive messages from infrastructure using V2I (vehicle to infra) communications;
• an information collection unit configured to collect vehicle information of the neighboring vehicles and vehicle information of the subject vehicle using sensors provided on the subject vehicle;
• and
• a control unit configured to select a target vehicle for being followed by the subject vehicle based on the vehicle information of the neighboring vehicles acquired by the communication unit, and to control the driving speed of the subject vehicle based on speed information of the selected target vehicle,
• wherein the control unit is configured to select the target vehicle by:
• selecting vehicles that travel in the same lane as the subject vehicle as a first group of potential vehicles of interest;
• selecting, from the first group of potential vehicles of interest, vehicles that exist within a predetermined distance as a second group of potential vehicles of interest, wherein distance is measured by at least one of the V2V communication, the V2I communications and the sensor provided on the subject vehicle;
• selecting, from the second group of potential vehicles of interest, vehicles in which a difference between speed information received by the V2V communication or the V2I communication and speed measured by the sensor is within a predetermined value as a third group of potential vehicles of interest;
• and
• selecting one vehicle in the third group of potential vehicles of interest as the target vehicle to be followed by the subject vehicle.