A Cyber-physical Approach for Emergency Braking in Close-Distance Driving Arrangements

In addition to fuel/energy savings, close-distance driving or platooning allows compacting vehicle flows and, hence, increasing throughput on congested roads. The shorter the inter-vehicle separation is in such settings, the more the benefits. However, it becomes considerably harder to guarantee safety, in particular, when braking in an emergency. In this article, we are concerned with this problem and propose a cyber-physical approach that considerably reduces the stopping distance of a platoon with inter-vehicle separations shorter than one vehicle length (i.e., 5 m) without sacrificing safety and independent of the road profile, i.e., whether on a flat road or in a downhill. The basic idea is to implement a cooperative behavior where a vehicle sends a distress message if it fails to achieve an assigned deceleration when braking in a platoon. This way, other vehicles in the arrangement can adapt their decelerations to avoid collisions. We illustrate and evaluate our approach based on detailed simulations involving high-fidelity vehicle models.