The goal is to make a xylophone-playing robot that is so cool.
Randy is compelling everyone to follow a formalized design process for this project. Here is what we've concocted:
What any design must satisfy in order to be acceptable.
- Hits keys
- Able to play at least 3 keys simultaneously
- Microcontroller-driven (i.e. does not require full computer)
- At least as cool as something made 90% out of wood
Things that a design should do. This will aid in selecting which concept to build. In order of importance:
- As cool as possible
- Preferrably makes a tukkatukkatukka sound as it runs
- Many simultaneous notes
- Fast time between notes, different or repeated
- Ability to control a wide volume range
Function decomposition and concept ideation
Based on the requirements, the problem is broken into a few abstract functions that it must perform. For each function, many means of performing that function are suggested.
|Hits keys||Hammers, Rocks, Linear drive|
|Drives key hitter||Clutch, Motor, Gravity, Springs, Electromagnet, Solenoid, Explosive, Rocket, Ion propulsion, Railgun, Coilgun|
|Returns key hitter||Springs/elastics, Motor, Electromagnet, Ion propulsion, most anything that could also be a driver|
By combining one option for each function, concepts are created.
|Hammer||Clutch||Springs||Mechanism would be similar to a Selectric typewriter: drive would be running constantly, each hammer would clutch onto the drive in order to hit the key.|
|Hammer||Spring||Motor||Spring would allow for a fast but uncontrolled strike, then motor would return it.|
|Rock||Gravity||Motor||Drop something on the keys, then pull it back up.|
|Linear||Gravity||Railgun||Drop onto the key, then shoot it back up in the air!|
- All concepts need a little bit of fleshing-out; a quick sketch of the mechanism will do.
- We might want more concepts than just those listed above.
- Concepts are scored in how well they meet the selection criteria.
- Typically, one concept is chosen as the "reference"; other concepts are ranked as better (+1) similar (0) worse(-1) in each criterion.
- Take rank times importance, sum for each design; higher is better.
- Exact score is not important - this is in inexact process - but the top ranked designs are the ones worth pursing.