Derived Requirement (glossary)

Constraint stated during the design activities which arise as a result of the selected solution (for example, a necessary mean or resource related to a technology, or an interface between two components of different sub-systems). (Faisandier 2011 (expected--not yet published))

Source

Faisandier, A. 2011 (expected--not yet published). Engineering and Architecting Multidisciplinary Systems. TBD: TBD.

Discussion

Scott Jackson comments:

This definition is not wrong: it is just a very narrow definition of derived requirements. I suggest the following two:

"Those characteristics typically identified during synthesis of preliminary product or process solutions and during related trade studies and verifications." (INCOSE Glosssary of terms -1998)

However the best definitions have to to with the hierarchical nature of systems. The following is adapted from Wasson (2006):

"a lower level performance based sibling action decomposed from an abstract parent requirement. The decomposed sibling action constitutes satisfactory accomplishments of the parent action."

In short a derived requirement is any requirement that occurs at one level below the parent requirement on the system hierarchy. The derived requirement may be mathematically determined from the parent requirement. For example, the energy that a brake must absorb in a car can be determined from the weight of the car, the speed of the car, and the required stopping distance.