Chapter 2

The Process of Design

Design Process

The 12-Step Design Process is:

1. Define the Problem2. Brainstorming3. Researching and Generating Ideas4. Identifying Criteria and Specifying Constraints5. Exploring Possibilities6. Selecting an Approach7. Developing a Design Proposal8. Making a Model or Prototype9. Testing and Evaluating10. Refining11. Creating or Making12. Communicating Process and Results

Define the ProblemAt this phase of the project, the problem is identified and defined.

Discussion of problem:

• Disposal and rechargeable batteries have been used to power everything from cellular phones to computers. The Hubble space telescope depends on batteries to power its electronics during night orbits.

• Because the space craft has been in service for 18 years, the batteries have come to the end of their service life.

• Example of solution: A new battery design that will replace existing batteries and thus extend the life of the spacecraft as well as provide more power for future instrument packages.

http://www.nasa.gov/mission_pages/hubble/servicing/series/battery_story.html

BrainstormingEach team member contributes his or her unique ideas in order to generate solutions to the problem.

Nickel-cadmium batteries

Lithium ion polymer batteries

Researching and Generating IdeasUsed to discover prior implemented solutions to particular design problems.

Currently, the Hubble space telescope is using nickel-hydrogen batteries.

Courtesy of JupiterImages/Plainpicture

Identifying Criteria and Specifying Constraints

Detail what you intend to do and the imposed limitations.

The battery must:• Not exceed 460 lbs• 36" x 32" x 11"• Min. of 75 amp-hours• Deliver 24 volts

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Exploring PossibilitiesExploring all possible solutions. (This phase requires attention to detail.)

• Lithium ion polymer batteries varies from 2.7 volts (discharged) to 4.23 volts (fully charged).

• Have to be protected from overcharge by limiting the applied voltage to no more than 4.235 volts per cell used in a series combination.

Courtesy Jim B. MacDonald

Selecting an Approach

Perform an assessment and then choose a design path.

I don’t really think this is the right way to make an assessment.

Courtesy of JupiterImages/Workbook Stock

Developing a Design Proposal

Create a clear documented description of the design.

Background: During Hubble’s sunlight (or day) orbit, the solar array panels provide power to the electrical components and charge the batteries. This supplies enough power to support Hubble during its night orbit.

http://www.nasa.gov/mission_pages/hubble/servicing/SM4/main/index.html

Making a Model or Prototype

With the design proposal completed, a model or prototype of the solution is constructed.

http://www.nasa.gov/mission_pages/hubble/servicing/series/battery_story.html

Testing and Evaluating

The model or prototype is tested to determine how well the design meets the criteria set earlier in the project.

Courtesy of Aiolos, www.aiolos.com

RefiningAny problems and/or concerns indicated in the testing phase are addressed in the refining phase.

Courtesy of Workbook Stock/JupiterImages

Creating or Making

At this point in the process, the design is sent to production.

Courtesy of Z Corporation

Communicating Process and Results

At this point in the process, the final documentation is prepared.