Assessing the safety benefits of CACC+ based coordination of connected and autonomous vehicle platoons in emergency braking scenarios

TL;DR

This paper evaluates the safety advantages of CACC+ over traditional CACC in emergency braking scenarios for autonomous vehicle platoons, using simulations to analyze collision probabilities, expected collisions, and impact severity.

Contribution

It introduces a comparative analysis of CACC+ versus CACC for safety in emergency braking, highlighting the benefits of multi-predecessor information utilization.

Findings

CACC+ reduces collision probability compared to CACC.

Using CACC+ decreases expected number of collisions.

CACC+ results in lower collision severity.

Abstract

Ensuring safety is the most important factor in connected and autonomous vehicles, especially in emergency braking situations. As such, assessing the safety benefits of one information topology over other is a necessary step towards evaluating and ensuring safety. In this paper, we compare the safety benefits of a cooperative adaptive cruise control which utilizes information from one predecessor vehicle (CACC) with the one that utilizes information from multiple predecessors (CACC+) for the maintenance of spacing under an emergency braking scenario. A constant time headway policy is employed for maintenance of spacing (that includes a desired standstill spacing distance and a velocity dependent spacing distance) between the vehicles in the platoon. The considered emergency braking scenario consists of braking of the leader vehicle of the platoon at its maximum deceleration and that of the following vehicles to maintain the spacing as per CACC or CACC+. By focusing on the standstill spacing distance and utilizing Monte Carlo simulations, we assess the safety benefits of CACC+ over CACC by utilizing the following safety metrics: (1) probability of collision, (2) expected number of collisions, and (3) severity of collision (defined as the relative velocity of the two vehicles at impact). We present and provide discussion of these results.