1. 1 1 Design Objectives Trees AAE 490B Week 2 Lecture 5 AAE 490B Week 2 Lecture 5

2. 2 2 2 Team assignment due next Wednesday/Friday Due Wednesday Prepare a mission statement for the opportunity description handed out in class today Friday Prepare an objectives tree to the mission opportunity statement handed out in class today.

3. 3 3 3 Agenda – Design objectives tree Goal – clarify design objectives and sub-objectives as well as the relationships between them Procedure Prepare a list of design objectives taken from: the design opportunity description or RFP; questions to client; discussion within the design team Order the list into hierarchical form – different level objectives Draw a diagrammatic tree of objectives – branches present relationships that will suggest means of achieving the design objectives

4. 4 4 4 Design Stages & checklist Client statement (Need) Problem definition 1.Clarify objectives 2.Establish user requirements 3.Identify constraints 4.Establish functions Functions? Conceptual Design 5.Establish design specifications 6.Generate alternatives Preliminary Design 7.Model or analyze design 8.Test and evaluate design Design specs?

5. 5 5 5 The Design Objectives Tree Client requirements, user needs, product purpose Facts The client may be uncertain about what he/she wants – or – may assume that the designer absolutely, positively understands what is needed. This is a recipe for disaster if you aren’t careful The client may also want to leave the designer with lots of freedom – that is a good thing, but also a danger What is an objectives tree? A list of design attributes An attempt to clarify and organize client/customer needs and wants taken from a list that contains abstract and concrete requirements – example “safe and reliable” A hierarchical list – move from top level to component levels as shown hierarchy List of attributes organize clarify Attribute = a quality or characteristic of the person, thing or group

6. 6 6 6 Objectives tree How do I begin to generate an objectives tree? Generate an attributes list List begins by doing things as a team – brainstorming about needs and wants Specify what a general statement means – example “safe=low risk to operator” Go back to client with questions Expand and clarify – ask questions like What? How? Why? What? Example – “How do we achieve this objective?” When do I organize the tree? How do I get this ? Wh y is this her e? Provide safe machine

7. 7 7 7 Objectives Tree diagram example Machine must be safe Low risk of operator mistakes Low risk of damage to work piece or tool Low risk of injury to operator Automatic cut-out on overload How? Why? Comments – the fewer levels the better Encourages you to think about means and ends There is no ranking between items – yet This is a team activity

8. 8 8 IED Robot OT: Super Team E IED Robot Versatile Long Endurance Mission Duration System Life All Terrain Indoors Outdoors Varied Payloads Safety Remote Operating distance Long Transmission Distance Autonomous Neutralize devices Detect Camera Capabilities Night Day Field of View Sense IED types Dispose Transport Detonate Economical Cheap To Purchase Cheap To Operate Cheap To Repair Reliability Durability Collin Morgan Aaron Smith Jared Odle Charley Hancock Kibum Kwon Kyle Donahue How? Why?

9. 9 9 9 Dym’s ladder design example “Design a new ladder for electricians or other maintenance and construction professionals working at conventional job sites” What features (attributes) do you want the ladder to have? What do you want the ladder to do? Why do you want it? When you develop design statements, ask: What does that statement mean? How are you going to do that? Why do you want to do that?

10. 10 Dym’s ladder attributes list (page 56) brainstormed and all over the place Should be useful Used to string wire and conduit in ceiling Maintain and repair outlets in high places Replace light bulbs and fixtures Used outdoors on level ground Used indoors on floors with smooth surfaces A folding ladder might work Step deflections should be less than 0.05 inches Must be safe Must meet OSHA safety standards Must not conduct electricity Should be relatively inexpensive Must be portable between job sites Should be light Must be durable Need not be attractive or stylish Should be reasonably stiff A folding ladder might work Could be a step ladder or folding ladder

11. 11 Constructing the tree what the client wants and what the users need Our original brainstormed list contains Goals & Objectives ends we try to achieve by making something happen attributes or behavior the client and system users will find attractive Things that the design “will be” as opposed to “must do” - the “being statements” “Stiff” is a being statement Objectives are also written as statements that “more (or less) of the goal is better than “less (or more) of the goal” Lighter is better than heavier. Objectives help us choose between designs Objectives can be measured somehow Constraints Functions Means or implementation

12. 12 Observations This list has lots of different types of statements Some are statements that can be answered “yes” or “no” “Must not conduct electricity” Ladder must be an insulator but can be from a wide variety of materials – statement means that design choices are fewer Statement should leave open a range of possible design answers “Should be relatively inexpensive” “Must be safe” not how it should be designed to be safe List will be augmented during team discussions List can change with time as design work proceeds List is used as the next step for requirements and QFD

13. 13 Organizing or ordering the objectives tree Organize identified objectives into higher levels of importance and sub-objectives Some statements will be a means of achieving higher level objectives Example – under safe you might have “automatic cut-out on overload” this is a means of achieving safety defined by low risk to operator. Re-write your objectives into ordered sets that group things under the highest level of objectives as possible – e.g. “safe operation”

14. 14 Looking for design constraints Constraints do not appear in the objectives tree Constraints are not objectives We do not design a ladder to meet OSHA standards as an objective so it does not appear in the tree Constraints are requirements, but they are also special restrictions or limitations on a behavior or value of a design aspect of the design performance Stated as clearly defined limits whose satisfaction is either yes or no (binary choice) Ladder is a conductor or it isn’t Step deflection is either less than 0.05 inches or not Constraints restrict the size of the design space Constraints allow us to clearly reject some designs or design components while objectives allow us to choose between alternatives, some of which are better than others

15. 15 Design Functions & Design Implementation defined their place in an objectives tree - none Functions - What the design is supposed to do Actions that the design must perform Functions are “doing” items Implementation or means Ways of executing the functions that the design must perform Items on the attributes list that suggest what the final design should look like – wood or fiberglass It is premature to consider these means in the objectives tree These are solution-dependent items

16. 16 Pruned ladder list minus constraints, functions and implementation Should be useful Used to string wire and conduit in ceiling Maintain and repair outlets in high places Replace light bulbs and fixtures Used outdoors on level ground Used indoors on floors with smooth surfaces Must be safe Must not conduct electricity Should be reasonably stiff Should be relatively inexpensive Must be portable between job sites Should be light Must be durable These items are inappropriate because they are constraints, means, implementations or functions Need not be attractive or stylish A folding ladder might work Could be a step ladder or folding ladder Must meet OSHA safety standards A folding ladder might work Step deflections should be less than 0.05 inches

17. 17 Pruned objectives list Ladder should be useful Used to string wire and conduit in ceiling Used to maintain and repair outlets in high places Used to replace light bulbs and fixtures Used outdoors on level ground Used indoors on floors with smooth surfaces Must be safe (for whom and under what conditions?) Should be reasonably stiff and comfortable for users Should be relatively inexpensive Must be portable between job sites Should be light Must be durable A safe ladder for electricians and others 1)The ladder should be safe 1)The ladder should be stable 1)Stable on floors and smooth surfaces 2)Stable on relatively level ground 2)The ladder should be reasonably stiff 2)The ladder should be marketable 1)The ladder should be useful 1)The ladder should be useful indoors 1)Useful to do electrical work 2)Useful to do maintenance work 2)The ladder should be useful outdoors 3)The ladder should be the right height 2)The ladder should be relatively inexpensive 3)The ladder should be portable 1)The ladder should be light weight 2)The ladder should be small when ready to transport 4)The ladder should be durable How? Answers “what do you mean by safe, marketable, useful … ? As you work into the outline you answer generic “how” questions. Why?

18. 18 Objectives tree lots of work – team exercise Safe ladder for construction Safe Marketable Portable Inexpensive Durable Useful Stiff Stable Indoors Outdoors Right height Light weight Small, transportable Electrical Maintenance Level ground On floors Constraints, functions and implementation means do not appear Added objective heading

19. 19 Where do we end the process? Keep going until you run out of “being” objectives and begin to encounter “doing” items – go about 4 layers deep What do we do with the items removed from the list? Keep functions and implementation for later design phases Put constraints back into objectives tree in an appropriate place, but CLEARLY identified

20. 20 Objectives tree lots of work – team exercise Safe ladder for construction Safe Marketable Portable Inexpensive Durable Useful Stiff Stable Indoors Outdoors Right height Light weight Small, transportable Electrical Maintenance Level ground On floors Added objective heading Must meet OSHA safety standards

21. 21 Summary The objectives tree is a method of generating an ordered list of what the design has to do to meet the client/user needs The objectives tree contains customer attributes that, when ranked and processed, will lead to a set of design specifications for the system to be designed.