Item Definition

When you analyze a vehicle system's functional safety, you first need to understand the item's functionality and define the boundaries of the item. In our example, the item is the lane assistance system.

Looking at the lane assistance system architecture,

you can see that the item boundary was drawn to include three sub-systems:

Camera system
Electronic Power Steering system
Car Display system

Your job in functional safety is to further refine the system to take into account potential malfunctions. To ensure functional safety, you might end up adding additional subsystems or elements to the original system architecture provided to you.

In general, the item definition will mention which systems are part of the item as well as any other information known about the item such as:

Functional concept of the product, which describes what the item is supposed to do; recall that functional safety engineering involves analyzing what happens when the system malfunctions, and the item does not do what it is supposed to do. So it is important to understand the product's purpose.
Operational and Environmental Constraints
Legal Requirements
National and International Standards Related to the Item
Records of previously known safety-related incidents or behavioral short-falls

Quiz: Lane Keeping Item

Lane Assistance Item

QUIZ QUESTION: :

Check your understanding of the lane assistance item by matching terms

ANSWER CHOICES:

Term A	Term B
Responsible for measuring the torque provided by the driver and then adding an appropriate amount of torque based on a lane assistance system torque request
Responsible for detecting lane lines and determining when the vehicle leaves the lane by mistake
The name of the item under consideration in the functional safety module
Functionality that vibrates the steering wheel when the driver drifts away from center by mistake
Functionality that turns the steering wheel back towards the center of the lane if the driver starts to drift away from center

SOLUTION:

Term A	Term B
Responsible for measuring the torque provided by the driver and then adding an appropriate amount of torque based on a lane assistance system torque request
Responsible for detecting lane lines and determining when the vehicle leaves the lane by mistake
The name of the item under consideration in the functional safety module
Functionality that vibrates the steering wheel when the driver drifts away from center by mistake
Functionality that turns the steering wheel back towards the center of the lane if the driver starts to drift away from center