? What is ASIL?

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ASIL refers to Automotive Safety Integrity Level. It is a risk classification system defined by the ISO 26262 standard for the functional safety of road vehicles. The standard defines functional safety as “the absence of unreasonable risk due to hazards caused by malfunctioning behavior of electrical or electronic systems.” ASILs establish safety requirements―based on the probability and acceptability of harm―for automotive components to be compliant with ISO 26262. There are four ASILs identified by ISO 26262―A, B, C, and D. ???????? ?? represents the lowest degree and ???????? ?? represents the highest degree of automotive hazard.

?????? ???? ?????????? ?????????ASILs are established by performing hazard analysis and risk assessment. For each electronic component in a vehicle, engineers measure three specific variables:

? Severity (the type of injuries to the driver and passengers)

? Exposure (how often the vehicle is exposed to the hazard)

? Controllability (how much the driver can do to prevent the injury)

Each of these variables is broken down into sub-classes.

?? Severity has four classes ranging from “no injuries” (S0) to “life-threatening/fatal injuries” (S3).

?? Exposure has five classes covering the “incredibly unlikely” (E0) to the “highly probable” (E4).

??Controllability has four classes ranging from “controllable in general” (C0) to “uncontrollable” (C3).

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All previous variables and sub-classifications are analyzed and combined to determine the required ASIL. For example, a combination of the highest hazards (S3 + E4 + C3) would result in an ASIL D classification.

Example:? A vehicle speed indicator on the dashboard display fails. It’s possible the indicator could show no information at all (i.e. it’s set to zero all the time) or it could display the wrong speed.

- In the first case, ?????? ?????????????????????????????? ???? ???????? ????????, since a driver could easily perceive the failure and then drive more cautiously. That scenario could be classified QM.

- In the second case, the failure is less obvious to the driver (e.g. it indicates 55 Km/h when it should indicate 65 Km/h), but ?????? ?????????????????????????????? ???? ?????????? ???????????????????? ????????????, so this scenario could be classified ???????? ?? or ????????-??.

? By contrast, say the driver’s brakes fail during a high-speed operational situation in crowded streets. This would have a serious effect on the driver’s ability to control the vehicle, and there is a chance the driver or others could get badly hurt as a result. This risk would be classified as ???????? ?? in this case

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