Intro to Physical Computing Fall, 2003 Jeff Feddersen
MPJA has little 5V motors for 39¢ a piece for orders of 5 or more.
Some old friends visited over the weekend. Anna, the girl, was fascinated with all my electronics junk. I taught her how to solder and she wired up some potentiometers and speakers for me. She was into making LEDs turn on, and before long she had set up a circuit where she could vary the brightness of the LEDs with a variable resistor. She's only 9 but made as much progress in a few hours as I had made in my first week in this class.
She asked me whether I enjoyed playing sports. I said, 'Not really.'
Thinking about the final project - here are some ideas (I suppose I should be farther along than at the brainstorm stage, but, oh well):
My hesitation with all of these involves my concern that they aren't original or interesting enough.
The robots described above have been done before, and the 'music' stuff is only interesting if the output sound is actually good music.
Generating tones based on environmental variables is basically the same as listening to a modem at slow speed or listening to static hiss on the radio.
There needs to be some algorithm that translates, for example variations in temperature, into a chromatic scale.
Youth is the time spent discovering the rules of life. Maturity is knowing the corollaries and exceptions.
These 'ant' robots from MIT are pretty cool, but I don't think I could build them, at least not in the next few weeks.
The more I collaborate with people, the more I come to realize that I'm bad at it. I think I'm destined for hierarchy, either as a grumbling minion, as a hapless middle-manager, or ideally as a tyrannical dictator. I would make a good dictator - I'd have way more edicts and decrees and stuff than anyone else. Although looking at tyrants in the past, it seems like fluency in a foreign language would be required, particularly Spanish.
I ordered 32 motors (6 5VDC 15° stepper, 6 12VDC 3.6° stepper, and 20 regular 5VDC motors). I'm leaning toward the millipede-style robot. I don't want to use an existing design or pre-built components (other than the motors), I'd rather come up with all the design and construction myself. The Head shuold have some kind of turning ability, but the body segments should be 'dumb' and just follow the head. I want it to walk rather than roll (walk and roll, baby!) and having loads of little legs should help the balance issue The image on the right is my current idea for powering the legs, similar to how the motion of the main piston on a steam engine is converted to rotational motion, except I want to go in the other direction: rotational to linear. Whereas on a train, the open slot on the arm is at the pivot attached to the wheel, in my idea, the open slot is at the pivot that is fixed to the body.
The tricky part (one of the tricky parts) will be to sequence the leg motion on each body segment so that those at the apex of rotation are supported by those at the nadir. Otherwise, the body segment will move more than the legs and the robot won't walk forward.
I don't know why I bought a bicycle. I never ride the thing. It's too much trouble to carry up and down three flights of stairs.
If I make the legs shorter than the height of the body, then the body segment will drag once per rotation, guaranteeing that the legs move up and forward without pushing the robot backwards.
I can't figure out whether it would be better for the left and right legs on each segment to walk in parallel or out-of-phase.
This is beginning to look like a series of cams more than anything else. Maybe I should just use those.
Scott Clifford is a really swell guy. He would never go on a murderous rage because of something he read in this blog.
For the head, I could put two photosensors on either side, and have them trigger legs on the opposite side so that it follows a light source - light on the left would make the right leg move, turning the head toward the left.
Got some Girl Scout cookies. Mmm, Thin Mints.
Each motor will need 5V, so do I have one central battery at the head or have each segment use its own battery? If I pass a single voltage down all the segments, there will be a 5V drop at each motor. If I use a AA battery on each segment, that will only be 1.5V per motor - not enough to power it, unless I use a capacitor to store power and release it as needed. Or I could use a 9V battery on each segment. I don't want it to go too fast, though. I could use gears to reduce the RPMs, I guess.
I'm ready to do the lab assignment,
P-Comp is clearly focused on programming more than electronics. I would rather have one class devoted exclusively to electronic circuits, and another that goes into midi, max/msp, etc.
Another idea: a 3D mouse. Imagine the rubber grip from a bicycle handle oriented vertically in a box. Springs from all directions keep the grip steady. Flex sensors are attached so that they can detect pulling/pushing, movement left and right, and up and down. They can also detect twisting around the three axes. This wouldn't be too useful for regular applications, but could be useful in 3d environments.
Finally tried Tom's stepper motor exercise. Kind of a pain when you don't know the order of the 6 wires. I got the gist of it, and got motion without resorting to any fancy Darlington transistors, just 2n2222, thank you very little.
A few weeks ago, for my Spatial Design class, I did a study of how horses run, specifically looking at Muybridge's famous photographs
I've gotten a few emails with complaints about some of the stuff I've written in these journals.
Not about the technical stuff, just about the various random thoughts I've put down.
Seiko Epson (I didn't know Epson was a Japanese company) has made the world's smallest flying robot. It's remote-controlled, so not a fully-independent autonomous robot, but with wireless communication as good as it is, it's reasonable to imagine a bug with its brains on the ground.
Another idea is to create a musical language that is understandable by both machines and people - something between the hiss of a modem and English.
I bought two of those flex sensors, which turn to be made by... Abrams Gentile Entertainment - not sure if that's a joke. They also make mediocre cartoons.
Option Explicit dim noteVar as integer Public Sub Main() call putpin(26,0) do noteVar = (getadc(15) * 2) + 36 if (noteVar > 96) then noteVar = 96 end if debug.print cStr(noteVar) loop End SubI've got arithmatic on my side.
I don't have a stinking midi cable! But what if... I were to just stick random wires into the jacks? Okay, you talked me into it.
I accidentally nudged my rather delicate setup and now the pulsing has changed, as though two or three frequencies are passing in and out of phase. It doesn't seem to matter whether the midi connector is grounded (pin 2), which tells me I've done something wrong, but it's all very harmonious
Now I know I've done something wrong. If I pull out all wires to pin 14 and com 1, I still get the same harmonious pulsing, which means it's a function of the electronics not anything else. Still, I was able to vary the tone with the variable resistors.
The sound has two measures: f# (half note) c# (half note) - f# (quarter) f# (quarter, one octave up) f# (quarter) c# (quarter)
Although the music was pleasant, I shut off the BX, but the keyboard kept playing the same sound. I pulled out the wires, and it kept playing. I must have set it up on some sort of oscillation. The keys still work, so I can jam along with the groove.
For eons, people have enjoyed mapping the musical scale to the color spectrum.
You can get comparable results by multiplying the original frequency by 1.1 to get it in terahertz.
The abundance of red and green in the chart has to do with the fact that our eyes are most sensitive to those two colors, not because of any bias on the part of the spectrum. Color is, of course, entirely subjective.
These are the numbers that, when multiplied by 240 (ie are transposed up by 40 octaves) map onto the spectrum of visible light. Other notes, such as middle C would need a different multiplier, in this case, 2^41. Douglas Adams' number, 42, would be the exponent of the multiplier for the octave below middle C. Maybe that's what he meant by saying that 42 was the answer to the question of the universe.
The above is based on standard tuning. Other tunings wouldn't make much difference. When multiplying by 1.1 trillion, small differences get magnified, but not enough to matter here.
F is an interesting note in that it happens to match exactly with the upper and lower ranges of frequencies of visible light.
That could be a coincidence, but I wouldn't be surprised if our brains use some sort of hardwired math that results in the spectrum of sound and color having the same bounds, albeit separated by many orders of magnitude.