[ISO26262]1. Vocabulary(기능안전 용어)

● fualt:

 abnormal condition that can cause an element or an item to fail (root cause of failure)

●Error:

 Discrepancy between (1) a computed, observed or measured value or condition, and (2) the true, specified or theoretically correct value or condition

● failure:

 termination of the ability of an item to perform a function as required (by the user)

● hazard:

 potential source of harm to people

● safe state:

 state of an item without an unreasonable level of risk

● FTTI(Fault Tolerant Time Interval):

 the transient time interval, during which an unsafe behavior is tolerable.

●EOTI(Emerfency Operation Tolerant Time Interval)

 whe a safe state cannot be reached, either directly or timely, or cannot e maintained, the item can transition to emergency operation for providing safety. The timespan in which emergency operation can be maintained without unreasonable risk is called EOTI

● Item:

 system or array of systems to implement a function at the vehicle level 

● system:

 set of components or subsystems that relates at least a sensor, a controller and an actuator with one another.

● component:

 non-system level element that is logically and technically separable and is comprised of more than one HW part or of one or more SW units

●H/W Part

 Portion of a HW component at first level of hierarchical decomposition(resistor, CPU of a microcontroller)

● other technology:

 technology different from E/E technologies that are within the scope of ISO26262

● external measure:

 measure that is separate and distinct from the item which reduces or mitigates the risks resulting from the item

====Types of failue

● Systematic failure

 failure related iin a deterministic way to a specific cause, that can only be eliminated by a change of the design, the design of the manufacturing process, or specification of the maintenance procedures

● random hardware failure

 failure that may occur unpredictably during the lifetime of a hardware element and that follows a probability distribution

====types of random hardware faults

● single point fault

 fault in an element that is not covered by a safety mechanism and that leads directly to the violation of a safety goal

●residual fault

 portion of a fault that by itself leads to the violation of a safety goal, occurring in a hardware element, where that portion of the fault is not covered by safety mechanisms

● dual point fault(multiple point fault)

individual fault that, in combination with another independent fault (other independent faults), leads to a dual point failure(multiple poiint failure)

●latent fault

 multiple point fault whose presence is not detected by a safety mechanism nor perceived by the driver within the multiple point fault detection interval

● safe fault

fault whose occurrence will not increase the probability of violation of a safety goal

● perceived fault

fault whose presence is deduced by the driver within a predefined time interval

●detected fault

fault whose presence is detected by a safety mechanism within a predefined time

====dependent failure

●cascading failure

 failure of an element of an item causing other elements of the same item to fail

● common cause failure

failure of two or more elements of an item resultin from a single specific event or root cause

====