# String stability and a delay-based spacing policy for vehicle platoons subject to disturbances

## TL;DR

This paper introduces a delay-based spacing policy for vehicle platoons that ensures all vehicles follow a common velocity profile and remains stable under disturbances, especially useful for hilly terrains.

## Contribution

It presents a novel delay-based spacing policy combined with a disturbance string stability concept and a control design approach in the spatial domain.

## Key findings

- Guarantees all vehicles track the same velocity profile.
- Ensures disturbances do not amplify through the platoon.
- Validated through simulation results.

## Abstract

A novel delay-based spacing policy for the control of vehicle platoons is introduced together with a notion of disturbance string stability. The delay-based spacing policy specifies the desired inter-vehicular distance between vehicles and guarantees that all vehicles track the same spatially varying reference velocity profile, as is for example required for heavy-duty vehicles driving over hilly terrain. Disturbance string stability is a notion of string stability of vehicle platoons subject to external disturbances on all vehicles that guarantees that perturbations do not grow unbounded as they propagate through the platoon. Specifically, a control design approach in the spatial domain is presented that achieves tracking of the desired spacing policy and guarantees disturbance string stability with respect to a spatially varying reference velocity. The results are illustrated by means of simulations.