Writing Product Requirements

1. Writing Product Requirements • translating customer words… • into • … realizable engineering requirements

2. 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!

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

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

5. Customer Needs - Example

6. 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)

7. Define Metrics - Example Customer Needs List of Metrics

8. Needs-Metrics Matrix

9. Setting Target Values Competitor Benchmarking Target Values

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

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

12. Appendix Other info…

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

14. 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!

15. 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 yourconceptual design review and again in yourdetail design review!

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

17. Process for Final Specs • Develop technical models of the product. • Develop a cost model of the product. • Refine target specifications, making well documented trade-offs as necessary. • Flow down specifications for overall system into sub-systems. • Set appropriate values for final specs.

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