Re: pic: Mini-Arm - Controller
 

Just this Control component has a lot of award potential!

Good luck!
:)

Re: pic: Mini-Arm - Controller
 

We used a Axis control code. It wasnt too easy to program this thing. Basically we used the difference between the pots and set the speed accordingly. Also this thing has been programmed with a lot of safety measures. It also has a timer set, so incase we get stopped by anything, it multiplies the speed forcing movement. Ask if anything else :D

Re: pic: Mini-Arm - Controller
 

Yea, i was origionally going to make a mini-arm to control ours, but then i decided to write inverse kinematics code! Unfortionatly, we ran out of time to actually TEST our robot, but it looks very hopeful. This way, we can control our 3 joint arm using 1 joystick. We can tell it to go anywhere in x-y space.

It was interesting to write, because i had to make my own integer trig library.

Re: pic: Mini-Arm - Controller
 

814 did the same thing last year with their stacking arm.
We won leadership in controls at Sacramento for it.

Re: pic: Mini-Arm - Controller
 

so whos car is now missing its headlight switch and knob? it looks like its off a VW.

Re: pic: Mini-Arm - Controller
 

Shhhhhh. Big Mike hasn't noticed yet...

Re: pic: Mini-Arm - Controller
 

We control a single rotating arm with a similar setup. The drive
to the motor is derived from the difference of the values returned
by the pots. This produces a torque on the motor that is proportional
to the error. The result, if you increase the gain to get good precision,
is a harmonic oscillator. If you run in to that, you add a damping force
derived from speed of the arm, calculated by reading its position on two
(or more) successive radio packet cycles between the OI and the RC.
The arm then behaves as a damped harmonic oscillator. With well
chosen damping it won't oscillate at all. Use quality pots that do a good
job of maintaining continuity as they are turned.

Re: pic: Mini-Arm - Controller
 

oh i have noticed, its just that my car is so pathetic that needing a pair of pliers to turn my headlights on doesnt change much ;) (good thing this is a joke or else i would be pretty mad my cars headlight knob was gone)

Re: pic: Mini-Arm - Controller
 

Funny story about this. The team was at the Bristol-Myers Squibb shop, and I kept hearing the programmers on our team and the BMS tradesmen talking about "pots", and I couldn't count the times I heard them make references to the "pots", since we were programming the arm. It took me most of the day to figure out that "pots" were potentiometers. Then everything started making sense. Alas, clarity.

Re: pic: Mini-Arm - Controller
 

You wouldn't believe how many pot jokes were flying around while we were making our arm controllers... :p

Re: pic: Mini-Arm - Controller
 

Sometimes, we even forgot which pot was hooked up to which part, and we used to upload the code and wonder what went wrong. Thank God for the "Kill Switch" :ahh:

Re: pic: Mini-Arm - Controller
 

Oh we'd believe it - I'm sure that it does on almost every team that uses pots. It gets much worse when you break one of them and someone accuses you of "smoking the pot" :rolleyes:


Don't feel bad - my blinker stopped working the other day. It still lights, but it doesn't "blink." It's quite interesting having to changing lanes or attempting to complete a Michigan Left turn while actuating a turnsignal by hand!!!

Note: Yes, I do even make the "blink" sound myself too.

Re: pic: Mini-Arm - Controller
 

Yeah, we actually did smoke one of them. I accidentally hooked the wires up backwards, so that ground and power were next to each other (that's what I get for not having the right colors of the thin wire I was using!)
When I turned it all the way to one side, it started to glow red and smoke came pouring out. We quickly pulled the power :)

Amazingly, it still worked for a while, then it crapped out.

Re: pic: Mini-Arm - Controller
 

I think team 308 was the first to do an arm about this, all the way back in 2000. Here is a thread about it: http://www.chiefdelphi.com/forums/sh...ad.php?t=10706 Unfortunately, I can't seem to be able to dig up any pictures of it.

Re: pic: Mini-Arm - Controller
 

A potentiometer has been called a pot since the early days of radio.
I have been asked for the "thingamajig" for the arm measurement,
to which I replied the proper way to ask for the part is: "Dr. Brooks,
I would like you to give me the pot." The teenagers in the shop thought
it was very funny. The nine dollar Bournes pots from digikey, very
good for continuity as you turn them, are, of course, smooth pots. In
our shop everyone was careful wiring them, so no one smoked the pot.