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Voice of the Engineer (VOE) Function Trees

Voice of the Engineer (VOE) Function Trees. Fall 2012-1. Functions (VERB NOUN pairs). Start with ranked groups of needs Create a list of functions that need to be accomplished to meet those needs VERB NOUN pair (support load, apply torque, store data, etc.) Does it need: Power

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Voice of the Engineer (VOE) Function Trees

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  1. Voice of the Engineer (VOE) Function Trees Fall 2012-1

  2. Functions (VERB NOUN pairs) • Start with ranked groups of needs • Create a list of functions that need to be accomplished to meet those needs • VERB NOUN pair (support load, apply torque, store data, etc.) • Does it need: • Power • Information • User interface • Supports • Enclosures

  3. Step 1: Formulate – Identify Core Functions Shopping carts That leaves us with… Function 1: Handle Products Function 2: Transport Products

  4. Step 2: Assume – Identify the subfunctions which Each Primary function must achieve Next, identify the further details or subfunctions that the shopping cart needs to provide. Focus on WHAT the shopping cart needs to do, in order to provide the functionality of each primary function.

  5. Step 2: Assume – Identify the subfunctions which Each Primary function must achieve • Function 1: Handle Products • Support Products • Contain Products • Protect Products • Function 2: Transport Products • Translate products • Stop moving • Rotate products

  6. Step 3: Chart - Function Tree in Graphical FormDescribe HOW you plan to meet your shopper’s need:

  7. Step 4: Execute – Fill in the details of the function tree, and articulate the interface specifications

  8. Constraints There might be other things that have to be met that are not functions -cost limits -production methods These constraints can be listed alongside the functions

  9. Functions interrelate • Flow of power (mechanical, electrical) • Flow of information (signals, sensors, actuators) • Flow of material (water, widgets)

  10. Example

  11. Functions (focus of brainstorming) • Brainstorming focuses on ways to achieve the functions

  12. Brainstorm on • Shopping cart handle

  13. Brainstorm on • Obtain direction information from user

  14. Specifications • Objective • Can be measured • Practical (test costing $10,000 won’t work) • Need to be measured • Complete - Relate to the customer needs

  15. Needs vs. Metrics • Metrics translate needs into objective things that can be measured. • “I need it to be light” • Product and battery but not charger must have a mass <= 1.5kg • This allows you to objectively see if a design meets the customer needs • One metric may meet more than a single need • House of Quality

  16. Specifications cover all needs • “House of Quality” • Some needs are covered by more than one metric • Some metrics cover more than one need

  17. House of Quality bicycle shock From Ulrich and Eppinger

  18. Metrics also can protect you • What if the customer is unhappy with the thing you produce which meets all the specifications (list of metrics)

  19. Non-standard metrics • “The system needs 3 different diameter wheels” • Yes/no • Spread in diameters • “The product must instill pride in the user” • Subjective • Focus groups/ surveys

  20. Caution! • Try not to spec. your project so that: • It is impossible (no solutions) • It requires costly exotic materials (unless needed) • There is only a single solution • It requires too much time to analyze or build • It requires fabrication processes that we don’t have access to • It is exceedingly dangerous or risky • It is not challenge at all • It’s ok to have 1 or 2 “reach” specs but not all of them • Specifications can drastically change the outcome

  21. Simple initial hand calculations • It’s very easy to set up an “impossible” set of metrics to be met • Weight: < 0.01 g • Volume: > 10 m^3 • Load carrying capacity: > 10 kN • Engineering analysis will help you determine a reasonable set of specifications

  22. Exercise • Mass of shopping cart: < 2 kg • Is this a reasonable spec?

  23. Shopping cart initial analysis • Load bearing capacity • Mass of cart • Frictional losses • Power consumption • Refueling times • Cost • Can you come up with a design that you can show will meet the specifications you list?

  24. Negotiation • What if you agree to meet an impossible specification? • How do you deal with creeping elegance? • What is creeping elegance? • Types of customers that you may have to manage.

  25. Next week • Continue specifications

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