ISO 23793-1:2024 高度道路交通システム — 自動運転のための最小限のリスク操作 (MRM) — Part 1:フレームワーク、直進停止と車線内停止 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.

A list of all parts in the ISO 23793 series can be found on the ISO website.

Introduction

A minimal risk manoeuvre (MRM) is the fallback function of an automated driving system (ADS) used to achieve a minimal risk condition (MRC) which is a stable, stopped state (see ISO/SAE PAS 22736).

In a scenario where the dynamic driving task is being performed by the ISO/SAE Level 3-5 ADS, an event which prevents the ADS from continuing the dynamic driving task can occur. Examples of such events include:

• a) for ISO/SAE Level 3-5 ADS, the failure of the ADS, automated driving component(s) or other vehicle component(s);
• b) for ISO/SAE Level 3 or 4 ADS, the risk that the ADS exits its operational design domain (ODD);
• c) for ISO/SAE Level 3 ADS, the failure of the fallback ready user (FRU) or passenger to take over the dynamic driving task when the ADS issues a request to intervene.

In response, the ADS initiates an MRM function to provide enhanced safety for all passengers and other road users. The MRM function selects the most appropriate MRM type to reduce the risk (taking into account the subject vehicle state and traffic conditions) and eventually stops the vehicle through vehicle control. In addition to longitudinal control, lateral control can be added for certain MRM types.

The MRM is not a system, but rather a functionality within an ADS."MRM" and"failure mitigation strategy" appear similar in that both functions stop the vehicle in response to an adverse event for ADS operating at Level 3 to 5 automation. However, they differ in that the MRM is a function of an ADS, whereas failure mitigation strategy is a vehicle function designed to automatically bring a vehicle to a stop when it has been incapacitated.

"MRM" and"object and event detection and response" (OEDR) based collision mitigation and avoidance systems such as a"forward vehicle collision mitigation system" (FVCMS) sometimes behave similarly, as they try to minimize the collision risk. However, they also differ in their purposes: collision mitigation and avoidance systems consider impacts with external objects during normal operations, whereas an MRM tries to stop the vehicle in order to limit risk under abnormal conditions (such as ADS system failures or violations of ODD conditions) by decelerating the vehicle. OEDR-based collision mitigation and avoidance will be executed independently of and in parallel to MRM.

This document can be used to define the MRM function of ADSs such as motorway chauffeur systems (MCS) (ISO/TS 23792-1) or low speed automated driving (LSAD) systems (ISO 22737).

1 Scope

This document addresses the minimum requirements for minimal risk manoeuvres (MRM), which are the response of an ADS to perform automated fallback to reach a minimal risk condition (MRC).

This document specifies the classification framework for MRMs. The classification framework establishes the concept of MRM operation, classification of different MRM types, and basic principles of the decision-making process to decide which MRM type can be performed based on the situation.

This document also specifies the minimum requirements of the control strategy and test procedures for the two simplest types of MRM: straight stop for type 1 and in-lane stop for type 2.

The scope of the MRM described in this document covers minimum requirements for ADS performance during MRM action, from initiation to termination, aimed at achieving an MRC. MRM action-specific safety requirements for robust system design, such as those specified in ISO 26262 and ISO 21448, are not within the scope of this document.

The MRM described in this document are intended to be used on light-duty vehicles equipped with Level 3-5 ADS.

The scope does not include methods for detecting ADS failures and the decision-making process to initiate an MRM. This is because there are numerous cases that can initiate MRMs, and there is no general agreement on classification of those cases in the industry.

2 Normative references

There are no normative references in this document.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography