Transcript Part I
The Design Process Abstraction & Synthesis Part I by Prof. Bitar Needs Assessment & Problem Formulation Homework #1 Need / Idea Perform Market Research HW#1 Customer Requirements Brainstorm / Perform Technical Research Product Specification Needs Assessment & Problem Formulation Abstraction & Synthesis Homework #2 Research Prior Art Brainstorm Possible Solutions HW#2 Perform Value Analysis Viable Options Apply Constraints Preferred Solution Abstraction & Synthesis Example Design Problem We like to have candles in the windows of our house, especially around the Holidays. The candles we currently have are plug-in, with long cords. Some are turned on manually, while others have a sensor to automatically turn on, when it gets dark outside. We have 12 windows with candles. …and everything was fine until …? Romeo ! (alias: Candle Kitty) “The Masked Marauder” Romeo has a bad habit of going from window to window, knocking down candles, breaking bulbs and getting tangled in cords… My solution? Not acceptable OK, I need your help… The Customer Requirements Explicit – Cat Safe – Look Nice – Different Colors – Automatic Implicit – Low Cost – Reliable / Durable – Low Maintenance Formal Brainstorming Session “The Idea Trigger Method” Phase 1: Phase 2: Phase 3: Idea Generation Phase Idea Trigger Phase Compilation Phase Brainstorming Session “The Rules” No Holding Back No Boundaries No Criticizing No Dismissing No Limits No Restrictions Phase 1: Idea Generation Take a few minutes to write down (list) your ideas on a piece of paper. Identify possible solutions. Identify possible features that the candles should have. Identify as many areas of concern as you can think of. Wild and crazy ideas are OK! Phase 2: Idea Triggering Now, as ideas are shared, eliminate duplicates from your list. If you think of anything else, write it down on ANOTHER sheet of paper. These are the new ideas triggered from the previous ones. This process can be repeated as often as necessary until all ideas are exhausted. Phase 3: Compilation Compile a list of all the ideas and begin to discuss the feasibility of each. Identify key areas of concern. Identify practical solutions. Identify a set of product requirements. A Possible List of Customer Requirements Safety / Durability – – – – – Heavy Base Unbreakable Bulb or LED Secure to Window Sill, Sash or Window Pane No Cords Low Voltage Aesthetics – Traditional Look – Interchangeable Color Bulbs or LEDs – Flickering Option Low Operating Cost – – – – Long Battery Life (Efficient) Rechargeable Solar Rechargeable Photo Sensor or Timer Researching Existing Products “The Prior Art” http://www.lightsforalloccasions.com/ http://www.sillites.com/photos.php U.S. Patent & Trade Office – Quick Search – Solar Powered Candle More Prior Art - Dissected Possible System Block Diagram Photo Sensor Solar Cell Charge Controller Rechargeable Battery Mode Selection Drive Circuit Flickering Control LED Technical Research Areas Solar Cells – Availability, cost, size, shape, output voltage, output current, silicon types, spectrum sensitivity. Charge Controllers – Voltage Regulation, Current Regulation, etc. Rechargeable Batteries – NiCad, NiMH, Other?, Overcharging & Under-voltage Concerns, etc. Drive Circuits – Transistor, Voltage Regulator, DC/DC Boost Converters, Charge Pumps, etc. LED’s – Colors, Voltage Levels, Current Requirements, Intensities, Illumination Angles, etc. Photo Sensors – Types, Interface Requirements Analog and/or Digital Processing – op amps, digital logic chips, microcontrollers A Practical Approach Start with the Distributors – www.digikey.com – www.mouser.com Then the MFG’s Data Sheet Repeat this process for each block or component in your diagram. Begin to consider the interfaces between blocks. Picking one aspect: LED’s Questions to Answer What LED’s are available? – Colors? Sizes? Shapes? What are the key LED specifications? What is the proper way to power an LED? How much do they cost? What companies manufacture LED’s? What companies distribute LED’s? How much energy is required for this application? Colors Infrared Red Orange Yellow Green Blue Violet Ultraviolet White Voltages Ranging from 1.6V to 3.2V depending on color (assuming a constant current of 20mA) Agilent White LED Spec. Sheet LED Specifications – Curves ! Max. Forward Current vs. Voltage Check: 20mA @ 3.2V (Typical) LED Specifications – Curves ! Relative Luminous Intensity Wavelength (nm) LED Specifications – Curves ! Spatial Radiation Pattern Check Viewing Angle !! LED is Chosen Block Diagram is Modified Photo Sensor Solar Cell Charge Controller Rechargeable Battery Mode Selection Efficient Drive Circuit Flickering Control White LED 3.2V @ 20mA (worst case) Here’s another… What about the Battery? (To Be Continued…) In the meantime, you come up with a list of questions.