EE15N: The Art and Science of Engineering Design Lecture 6: Models and Prototypes

1. EE15N: The Art and Science of Engineering DesignLecture 6: Models and Prototypes • Announcements • Due at Midnight Tonight: First Writing Assignment & Weekly Meeting Notes • Due next week: Morph Chart (considering alternative designs). Prototype/model/proof of concept (Optional) • Mathematical Modeling • Models vs. Prototypes vs. Proof of Concept • Design of Models & Prototypes • Introduction to Modeling • Example: Mathematical Modeling of a Step Ladder

2. Five-Stage Descriptive Model Client Statement Problem Definition Conceptual Design Preliminary Design Mathematical models are used here Detailed Design Final Design Design Communication

3. Models • What is a model? • A miniature representation of something • A description of something (e.g. an atom) that cannot be directly observed • A mathematical description of something • Many types of models • Words • Drawings or Sketches • Physical Models • Computer Programs • Mathematical Formulas

4. Mathematical Models • What is a mathematical description of something for design purposes? • Mathematical representation of the behavior of real devices or objects. • Used to predict behavior in different settings • Used to determine performance/avoid failure • Used to create design specifications

5. Questions Regarding Models • Goals: Why do we need a model? • What do we want to find with this model? • Background: What data are we given? • What can we assume? • Predictions: What will our model predict? • Are the predictions valid? • Can we verify the model’s predictions? • How should we develop this model? • What are the appropriate physical principles we need to apply? • Results: Can we improve the models? • How will we use the model?

6. Building a Mathematical Model • Abstraction • Identify the phenomena to be emphasized, i.e. what phenomena must the model capture • Scaling • Scale the magnitude or size of quantities in the model to match the level of abstraction • Lumped Elements • Determine what parts of the object can be considered together to simplify the problem

7. Example: Mathematical Model of a Ladder Rung • Components of the model • Free body diagram of ladder • Model for ladder rung with a given force • Design and optimization based on model • Design criteria • Design considerations • Design tradeoffs

8. Models vs. Prototypes • Similar but with two distinct differences • Intention • Testing Environment • Prototype are working models of designed artifacts. They are tested in the same operating environment. • Models represent some devices or processes. They are typically tested in controlled environment.

9. Proof of Concept • Targeted Model • Used to test whether a new concept, or a particular device or configuration, can be shown to work in the manner it was designed. Proof of Concept Model Prototype

10. To Prototype or Not Prototype? Decision to prototype or not depending on a number of factors: • Size and Type of Design Space • Cost of building a prototype • Ease of building that prototype • Role that a full-size prototype might play in ensuring the widespread acceptance of a new design • Number of copies of final artifact that are expected to be made or built

11. You decide to build a model and/or protocol; now what? Questions to ask Who will make it? How will it be made, and from what? Where will parts/components come from? How can it be built safely? How much will it cost?

12. Group activity For your project, how would you use each of the following during the design process: - Model - Prototype - Proof of concept

13. Today’s Speaker Jeff Karras Levensohn Venture Partners