Scenario consistency

Internal consistency

A scenario is internally consistent if all the modes are explicit, and the selected modes are in the design scope (namely, they comply with the operational rules) .

Exceptional scenario

A scenario is exceptional if it is not consistent, namely, if it is either ambiguous, or the selected modes do not comply with the rules.

Example

The Torrey Canyon accident involved an exceptional scenario, due to the scenario ambiguity.

Assuring the scenario consistency

  To ensure that the operator's intentions communicate with the machine, the effective scenario should be consistent, implying:

• Explicit modes: All the modes should be defined in the requirement specification
• Mode selection: The operator may be able to select them using a scenario Selector
• Check internal consistency: The activity Selector should check if the effective scenario is consistent
• The activity Selector should generate an alarm if the scenario is not consistent.

Related topic

Updated on 09 Jan 2017.