Writing Product Requirements translating customer words into realizable

Writing Product Requirements translating customer words… into … realizable engineering requirements

Rationale for Requirements • Need to know the target and when you have reached it. • • • Agreement among stakeholders on product requirements before design begins. Allows you to create a budget and schedule for product development. Use requirements to prevent scope creep!

Needs Requirements Customer Needs (subjective – what customer wants) Product Requirements System Requirements Component Requirements Technical specifications (measureable)

Needs Requirements Approach Customer Needs (subjective – what customer wants) 1. Compile a list of needs 2. Organize by attributes (if possible) 3. Prioritize by importance Engineering Requirements A. Define Metrics Specific B. Benchmarking Measurable (units) C. Set Target Values Achievable Results-focused Time-bound

Guidelines for Metrics • • • Each customer need single metric (if possible) Metrics What the product must do (not how it will be achieved) Consider criteria for comparison in marketplace (support the Value Proposition)

Needs-Metrics Matrix

Engineering Requirements Be ready to show Engineering Requirements at Snapshot Day #1!!

Example The noise from the motor shall be quiet enough for an operator to use it for a full 8 hour day. Requirement(s): Noise shall be no greater than 65 d. Ba in any operating condition as measured from the operator’s ear location. Operators: Range 5 th %tile female to 95 th %tile male

Appendix Other info…

Process for Target Specs 1. Create a list of customer needs. (by-product of client interview) 2. Prioritize customer needs (by importance). 3. Prepare a needs-metrics matrix. 4. Compile benchmarking information. 5. Establish ideal as well as marginally acceptable values. 6. Set appropriate target values.

Tips on Selecting Metrics • • • Ideally each customer need would correspond to a single metric, and the value of that metric would correlate perfectly with meeting that need. In practice, several metrics may be necessary. Metrics should be dependent, not independent, variables. Specs indicate what the product must do, but not how the specs will be achieved. Show a table of metrics at first semester Snapshot event!

Tips on Selecting Target Values 5 ways to express target values… - At least X - At most X - Between X and Y - Exactly X - A set of discrete values Validate metrics and target values in your conceptual design review and again in your detail design review!

Summary • • • Requirements are typically established at least twice. Immediately after identifying the customer needs, the team sets target requirements. After concept selection and testing, the team develops final requirements. Final requirements are developed by thoroughly assessing actual techno-logical constraints and production costs. They should be based on rigorous analytical and physical modeling.

Process for Final Specs 1. Develop technical models of the product. 2. Develop a cost model of the product. 3. Refine target requirements, making well documented trade-offs as necessary. 4. Flow down requirements for overall system into sub-systems. 5. Set appropriate values for final requirements.

Helpful References Ulrich and Eppinger, Product Design and Development, 5 th Edition, Mc. Graw Hill, 2012. Hatley and Pirbhai, Strategies for Real-Time System Specification, Dorset House, 1998. Rechtin and Maier, The Art of Systems Architecting, 2 nd Edition, CRC Press, 2000.