The notion of ISO 26262 Functional Safety Standards was initially tailored for road vehicles under 3500 kg, concentrating on the safety dynamics of cars and passenger vehicles. While motorcycles were not explicitly excluded, the primary emphasis revolved around the safety of four-wheeled vehicles.
Instances like a malfunctioning ABS system in motorcycles elevate the risk to both the bike and the rider, compared to a car. The motorcycle geometry like centre of gravity, wheelbase, Trail, Rake angle makes a big difference in the vehicle dynamics. Also, the responsibility of balancing a stationary motorcycle falls solely on the rider, setting it apart from the controllability of a car in such scenarios. This sparked discussions on need of separate considerations regarding motorcycle safety.
A significant transformation unfolded in 2018 with the unveiling of an updated version of the ISO 26262 standard. This modification expanded the scope of standard from „road vehicles up to 3500 kg“ to „road vehicles excluding mopeds,“ thereby incorporating motorcycles, buses, and trucks into the realm of ISO 26262 functional safety.
- I. Differences in ISO 26262 Guidelines for Motorcycle Functional Safety
- II. Advocating Safety Culture
- III. Re-defined Confirmation measures:
- IV. Hazard Analysis and Risk Assessment (HARA):
- V. Modifications in Vehicle Integration Testing:
- VI. Scope of Safety Validation:
- VII. Impact of the New ISO 26262 Version on Motorcycle Safety:
Differences in ISO 26262 Guidelines for Motorcycle Functional Safety
New Terminologies Introduced
The updated standard introduces several new terminologies to enhance precision and clarity in the realm of motorcycle safety.
— expert rider (who has the skill to evaluate controllability)
— motorcycle
— Motorcycle Safety Integrity Level (MSIL) and
— Controllability Classification Panel (CCP)
Advocating Safety Culture
• Aligned with Part 12, organizations are required to define explicit process and work instructions as part of their Quality Management System (QMS). This entails seamless integration with other standards, including cybersecurity (ISO 21434) and Functional Safety.
• The establishment of measures for continuous process improvement, by taking the lesson learnt from the past ISO 26262 projects that were executed successfully.
• Additionally, empowering the motorcycle safety team with substantial authority ensures proficient execution and adherence.
Re-defined Confirmation measures:
Within the functional safety lifecycle, confirmation measures, comprising reviews, assessments, and audits, play a pivotal role.
Table 1 of Part-12 introduces a re-classification of these measures for the motorcycle sector that will replace the table from Part 2.
• A notable difference is the omission of ASIL D since the highest Motorcycle Safety Integrity Level (MSIL) is mapped with ASIL C. Majority of the work products (except HARA and Impact Analysis) only require I2 level of independence
• Adherence to the independence levels in the table dictates the execution of confirmation measures, encompassing reviews and functional safety audits.
• Certification pursuit mandates a functional safety assessment
Example:
Table 1 – Required confirmation measures, including the required level of independence.
These guidelines serve as guiding principles, to produce a significant influence over processes like Hazard Analysis and Risk Assessment (HARA) and safety validation that are essential in the development of ISO 26262-compliant software and hardware tailored for two-wheelers.
Hazard Analysis and Risk Assessment (HARA):
The process of HARA undergoes modifications, considering the safety in a two-wheeler ecosystem depends on multiple external factors. For instance, rider responsibility and external factors such as helmets, protective gears, and training contributes to motorcycle safety.
A Hazard may result also from the rider’s behaviour and not necessarily from a failure. For example, the motorcycle is not inherently designed to navigate safely through a snowy road unlike a car. If the rider decided to drive in such a situation, he is accepting a higher degree of Risk.
Hence motorcycle-specific hazard analysis and risk assessment emphasize more on rider behaviour for determining the Motorcycle Safety Integrity Level (MSIL) – a motorcycle counterpart of ASIL.
Adapting the operational modes, correct and incorrect vehicle usage, is also crucial for the malfunction analysis of a motorcycle. (E.g. Road Racing, motor cross is not considered as a normal usage).
Part 12 also introduces the concept of using a CCP (Controllability classification panel) which assigns controllability class by considering different results such as evaluation of motorcycle controllability performed by expert riders, motorcycle dynamics, rider behaviour etc. Controllability measures specific to two wheelers like weight shifting, declutch, counter steer are also considered.
Derived from HARA, MSIL serves as the motorcycle counterpart of ASIL. MSIL is also determined based on Severity (S), Exposure (E) and Controllability (C) like the ASIL as per provided in the Table 5 of part 12.
Annex B in the part 12 covers some guidelines for severity, exposure, and controllability adapted for motorcycle usage (E.g. Driver is trained, experienced and in good condition).
Table 5 – MSIL Determination
Example:
Unintended vehicle acceleration at a junction MSIL C: (Case 1)
S=3 Side collision (passenger car into side of motorcycle) at typical main road vehicle speed
E=3 Stopped at traffic light or intersection happens 1 % to 10 %
C=2 More than 90% of the drivers avoid damage by applying brakes, declutch
The mapping of MSIL and ASIL is the key difference here as this mapping is crucial for developing software/hardware components in accordance with the mapped ASIL grade. Also, the derived safety goals need to be mapped to the corresponding ASIL which enables a seamless transition into the product development phase (Part-4), that is still relevant and applicable for motorcycles. Table 6 from part 12 provides this mapping.
Table 6 – Mapping of MSIL to ASIL
Modifications in Vehicle Integration Testing:
The ISO 26262 standard introduces significant modifications in Part-4, focusing on system-level product development for motorcycles. Tables 7 and 8 provide guidelines for implementing functional safety requirements and ensuring correct functional performance, accuracy, and timing of safety mechanisms at the vehicle level for the motorcycles.
• Concerns over rider safety prompt the selection of alternative test methods or the transfer of vehicle integration test activities to other sub-phases
• User tests with normal users as testers are impractical for motorcycles
• Real-life conditions simulated under controlled environments.
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Scope of Safety Validation:
Safety validation covers:
• Controllability, intended use and misuse
• Effectiveness of external measures
• Effectiveness of elements of other technologies
• Assumptions influencing ASIL mapping from MSIL and
• Aspects that can be checked only in the final vehicle
This comprehensive approach ensures a thorough evaluation of motorcycle safety.
Impact of the New ISO 26262 Version on Motorcycle Safety:
The introduction of motorcycle safety gained a positive response in general. While larger Original Equipment Manufacturers (OEMs) were already prioritizing motorcycle safety, smaller players are now intensifying their focus.
The incorporation of advanced systems like infotainment, ABS, and Battery Management Systems in two-wheelers emphasizes the growing importance of functional safety.
With a formal ISO 26262 standard for motorcycles now available, a clearer pathway to ensuring motorcycle functional safety emerges, promising a future of safer motorcycles for all. If you have more questions about safety of motorcycles, feel free to connect with us for further clarification.
Gnanagiri Balasubramanian is a Chief Safety Expert at CYRES Consulting, with extensive experience in both the automotive and medical sectors. A seasoned professional in Functional Safety (ISO 26262), Automotive Cybersecurity (IEC 21434), and Medical Risk Management (ISO 14971), Gnanagiri has a proven track record of guiding organizations through the complexities of developing safety-critical systems, from risk assessment to safety lifecycle management. With a strong consulting background, he is committed to delivering high-quality safety concepts while ensuring compliance with industry standards. Gnanagiri holds a bachelor’s degree in electrical and Electronics Engineering, specializing in microcontroller and SoC safety, and is also a TÜV-certified Automotive Cybersecurity Professional.
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