Spring Turkey


Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 12

Obligatory Fat Albert reference:
Randall: Mushmouth, you're like p-comp on Thanksgiving.
Mushmouth: Whabat dobo youbou meabean?
Randall: No class

If I do the centipede robot, I could either make the segment wheels always turn together, relying on the head to pull them in the right direction, the way an 18-wheeler relies on the cab to turn. Or, I could have the segment wheels turn separately, based on a signal that's passed down from the head (right wheel to turn left, and vice versa). But that would mean each segment turning on its own, and the whole thing would move diagonally. Maybe I could just reduce the power sent to the one wheel rather than cut it off during a turn.

Tom Servo

Whatever I make will need to do something interesting, and one possibility is to have the ability to navigate a maze. So I need some component that can act as sonar or radar. I have a sensor (I think IR) and I want to see what values I get.

With the sensor grounded and in pin 13, I use the following basic code:

Sub main()
	call delay(0.5)
	call putPin(26,0)
		debug.print cstr(getADC(13))
end sub
Values fluctuate between 0 and 3.
Passing my hand in front of it moves the range from 0 to 10.
Covering the sensor with my thumb changes the range from maybe 10 to 35.
Covering the sensor with my hand changes it to 200 to 350.
Covering it with a battery changes it to 500 to 580.
I can't get values higher than that. This tells me it must be sensing frequencies outside the range of visible light, since my thumb was more transparent than my hand, and a solid battery was more opaque than that.

By multiplying the ADC value by 10 or so, I have a decent obstacle-detector. Low numbers mean the path ahead is open, higher numbers mean something is in the way. But I have only one. If I had two I could put one on each side to have all the navigation ability in the hardware. I like that idea. Relying on programming always feels like cheating. I could code the BX to turn the bot randomly left or right whenever it detects an obstacle, but that would lead to problems in box canyons.

Walking Chair

Just ordered a bunch of sensors of various types to help with the obstacle-detection. The little components are always cheaper in bulk so I always end up getting 10 instead of just 1 or 2. I hope I use this stuff next year. I'm blowing a lot of money on this class. But I think it was Thomas Edison who said, "To invent, you need a good imagination and a pile of junk." So I'm working on my pile. In Honor of Philip K. Dick, I call it my "Kipple Chest".

Mecha Leg

The image on the left is from www.zzz.com.ru, a good site for robotics and other stuff of that nature. A recent article detailed the D-9, essentially a remotely-operated bulldozer outfitted with machine guns, built by the US and used by the Israelis against Palestinians.
The leg is part of a mecha design that I may try to integrate in my final project. The advantage is that separate beams are used for weight-bearing and propulsion.

Idea: holiday lights that can change color. Instead of home-owners having to change strings of lights for Halloween, Christmas, or whenever people put up lights, just have one string with one red, one green, and one blue extra-bright LED clustered once per foot or so. A control box at one end of the string allows you to set all lights to, e.g. white (full RGB), pink (R100% G80% B80%), yellow (R100% G100% B0%), etc. That would make money.
But actually, strings of lights would have to ru on AC. AC LEDs exist, but they're expensive and clunky. It looks like they use a DC converter in the base, while the LEDs are still DC.

If I do any kind of narrative or documentary work (especially for kids) at ITP, I want to do something on 'Sea Monsters'. There are so many crazy creatures living at the bottom of the ocean, and kids would be totally into that, particularly if there are good photos.

Matt Slaybaugh
ms171 at nyu.edu