Need Analysis
Needs arise from things like:
- Safety and quality of life
- Product or system improvement
- Commercial incentive
- Personal experience
- Scientific advances
We do a need analysis to express why the project exists.
Recognizing Need
- We articulate need as an expression of dissatisfaction with the current situation (problem statement)
- We do not express need as a solution
- By determining need, you can now move towards the development of a specific design goal
Problem Definition
Structured framework for defining the problem
- Problem statement → big picture / goals
- Objectives → functional requirements
- Constraints → restrictions
- Criteria → how do we choose a design?
Problem Statement
- A problem statement is a brief ideal response to need assessment
- Very broad and neutral (just touch on the problem we have)
- Divide a problem in function and design goals
Function and Goals
- Description of the functions and goals the solution should have
- Talks about what the solution does not how
Design Specifications
- Objectives
- Constraints
Objectives
- Use functions and goals to develop objectives
- Quantifiable expectations of performance
- Should be unambiguous and have units (quantifiable)
Constraints
- Required design and performance parameters
- Reject designs that do not satisfy the constraints
- Types
- Yes/No constraints
- Equality constraints
- Inequality constraints
- One sided inequality constraints
- Two sided inequality constraints
Objectives and Constraints
- Specs / performance parameters should not be an objective AND a constraints, its one or the other.
Objectives can often be recast as constraints, and the other way around.
Criteria
- These are attributes of the design that are used to choose a specific design option
- Criterion should be unambiguous, concise, specific, quantifiable and independent of each other