Investigating Functional Redundancies in the Context of Vehicle Automation - A Trajectory Tracking Perspective

TL;DR

This paper explores how functional redundancies in vehicle actuators can enhance safety in automated driving by enabling fault-tolerant trajectory tracking, demonstrated through a model predictive approach for over-actuated vehicles.

Contribution

It introduces a fault-tolerant trajectory tracking method for over-actuated vehicles, analyzing how redundancies can compensate for actuator degradations within safety constraints.

Findings

Redundancies can compensate for certain actuator failures.

Degradations at physical limits cause significant trajectory deviations.

Small steering angles may be critical under certain conditions.

Abstract

Level 3+ automated driving implies highest safety demands for the entire vehicle automation functionality. For the part of trajectory tracking, functional redundancies among all available actuators provide an opportunity to reduce safety requirements for single actuators. Yet, the exploitation of functional redundancies must be well argued if employed in a safety concept as physical limits can be reached. In this paper, we want to examine from a trajectory tracking perspective whether such a concept can be used. For this, we present a model predictive fault-tolerant trajectory tracking approach for over-actuated vehicles featuring wheel individual all-wheel drive, brakes, and steering. Applying this approach exemplarily demonstrates for a selected reference trajectory that degradations such as missing or undesired wheel torques as well as reduced steering dynamics can be compensated. Degradations at the physical actuator limits lead to significant deviations from the reference trajectory while small constant steering angles are partially critical.