Mode Switching and Smooth Motion Generation for Adaptive Cruise Control Systems by a Virtual Lead Vehicle

The adaptive cruise control system maintains the appropriate distance to the lead vehicle when a lead vehicle exists, otherwise, it maintains the desired speed. These two objectives may be achieved by having two controllers, one for each objective, and a control mode switching logic. Introducing the virtual lead vehicle, however, only the distance control algorithm is used and the structure of the system can be significantly simplified. The speed and the location of the virtual vehicle are given by the control system according to the current situation. Smoother responses are achieved by the virtual lead vehicle scheme compared to the conventional mode switching scheme. The virtual lead vehicle scheme also generates smooth reaction for the host vehicle when the lead vehicle cut out or a vehicle cuts in from a side lane.