Trade study
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Atrade studyortrade-offstudy,also known as afigure of merit analysisor afactor of merit analysis,is the activity of amultidisciplinaryteam to identify the most balanced technical solutions among a set of proposed viable solutions (FAA 2006). These viable solutions are judged by their satisfaction of a series of measures orcost functions.These measures describe the desirable characteristics of a solution. They may be conflicting or evenmutually exclusive.Trade studies are commonly used in the design ofaerospaceandautomotivevehicles and thesoftwareselection process (Phillips et al. 2002) to find the configuration that best meets conflicting performance requirements.
The measures are dependent on variables that characterize the different potential solutions. If the system can be characterized by a set ofequations,one can write the definition of the trade study problem as: Find the set ofvariables,xi,that give the best overall satisfaction to the measures:
- T1= f1(x1,x2,x3.....)
- T2= f2(x1,x2,x3.....)
- T3= f3(x1,x2,x3.....)
- TN= fN(x1,x2,x3.....)
Where Tjis a target value and f(...) denotes somefunctionalrelationship among the variables. Further, the equality between the target and the function may be a richer relationship, as will be developed below. If the equations arelinear,as in the production volume example used as a starting point below, then this problem is solvable usinglinear programmingtechniques. Generally, one or more of the targets is not fixed at a specific value, and it is desired to make these T values as large or small as possible. These are generally referred to as cost functions, and the other measures are treated asconstraints.
If the situation was as described above, formal optimization or linear programming methods would work totally. However, in practice, needed information is:
- Uncertain
- Evolving - new information is being developed that affects the trades
- Bothqualitativeandquantitative
- Comes from conflicting sources - insystems engineering,many people have some of the information needed; no one person has it all.
- The best choice comes from a team, building a sharedmental modelof the situation.
See also
[edit]References
[edit]- FAA, System Engineering Manual Version 3.1, Section 4.6, Trade Studies, Federal Aviation Administration, 2006,[1]
- Phillips, B. C. and S.M. Polen, Add Decision Analysis to Your COTS Selection Process, Crosstalk, April 2002
- Ullman D.G. and B.P. Spiegel, Trade Studies with Uncertain Information, Sixteenth Annual International Symposium of the International Council On Systems Engineering (INCOSE), July 2006.[2]