pic: Mini-Arm - Controller [Archive]

nuggetsyl

25-02-2004, 22:23

so is that used to control your arm during the match? or simply as a mini mock up of your arm?
that is how we control the arm that way it makes it easier for the driver. Trying to drive this arm with a joystick would be toooooooooo much.

Max Lobovsky

25-02-2004, 22:26

so you actually control the real arm by moving the model arm? Do you use encoders or what to measure its placement?

mightywombat

25-02-2004, 22:31

nuggetsyl

25-02-2004, 22:31

we use pots to mesure where the robots are is

shaun

Ryan Foley

25-02-2004, 22:33

that is one of the coolest things I have ever seen. Great job 25!

nuggetsyl

25-02-2004, 22:34

Pots are most likely used. We did the same thing last year and it works sooo nice, as long as you have the time to tune the code to react correctly to the movement in the model. I am curious. How did you guys do it? Is it as simple as finding the difference between the actual and the requested pot values, dividing by a constant and adding the signed int to 127? I'm still working on code for a model, right now we are using joysticks and probably will for competition but its a project of mine.... How do you do it?
well i am sorry i can not answer that not because i do not want to but because that would have to come for one of the kids programing it rob or bharat. Programing the robot is something i can not do but i am sure once one of the guys see this the will tell all,

uvabrad825

25-02-2004, 22:44

that is truly awesome...

pras870

25-02-2004, 22:47

I must say, that is a genuine idea. I thought about making a potentiometer to create a control for our elevator and/or arm elbow, but it was not nearly as engenious as this. Reminds me a lot of a boat throttle now that I look at it :cool:

Sscamatt

25-02-2004, 22:48

i saw one of those last year...i thought it was like the coolest thing...great job! (i want one)

nuggetsyl

25-02-2004, 22:55

i saw one of those last year...i thought it was like the coolest thing...great job! (i want one)
wow which team had one

Nick Fury

25-02-2004, 23:03

I would like to see a wiring diagram of your controller if you happen to have one.....perdy please?????

nuggetsyl

25-02-2004, 23:18

I would like to see a wiring diagram of your controller if you happen to have one.....perdy please?????
crap on me right now i do not have one but i can get you one for the nj reagional

Greg Needel

25-02-2004, 23:25

we have a control for our arm also that uses pots to control height.....ours is a little simpler as in we are using 1 knob but we have stops at the common heights ie. top of the goal, hanging height....so it takes the guess work away from the drivers

Rich Wong

26-02-2004, 13:52

that is how we control the arm that way it makes it easier for the driver. Trying to drive this arm with a joystick would be toooooooooo much.

Just this Control component has a lot of award potential!

Good luck!
:)

Bharat Nain

26-02-2004, 17:11

Pots are most likely used. We did the same thing last year and it works sooo nice, as long as you have the time to tune the code to react correctly to the movement in the model. I am curious. How did you guys do it? Is it as simple as finding the difference between the actual and the requested pot values, dividing by a constant and adding the signed int to 127? I'm still working on code for a model, right now we are using joysticks and probably will for competition but its a project of mine.... How do you do it?

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

Adams High Man

26-02-2004, 21:44

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.

Alaina

27-02-2004, 16:23

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

KenWittlief

27-02-2004, 16:56

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

Aignam

27-02-2004, 18:09

so whos car is now missing its headlight switch and knob? it looks like its off a VW.
Shhhhhh. Big Mike hasn't noticed yet...

eugenebrooks

28-02-2004, 01:15

How did you guys do it? Is it as simple as finding the difference between the actual and the requested pot values, dividing by a constant and adding the signed int to 127? I'm still working on code for a model, right now we are using joysticks and probably will for competition but its a project of mine.... How do you do it?

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.

Mike Schroeder

28-02-2004, 01:51

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

Aignam

28-02-2004, 08:36

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.
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.

steven114

28-02-2004, 10:34

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

Bharat Nain

28-02-2004, 10:36

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:

Swan217

28-02-2004, 10:44

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

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:

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)

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.

steven114

28-02-2004, 10:47

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.

Joe Ross

28-02-2004, 11:09

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/showthread.php?t=10706 Unfortunately, I can't seem to be able to dig up any pictures of it.

eugenebrooks

28-02-2004, 19:16

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.

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.

Pierson

28-02-2004, 20:05

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

Our team made a very similar arm controller and yes... our programmers and electricians were having way too much fun with the pot jokes.

Arefin Bari

28-02-2004, 22:58

wow which team had one

SPAM ... team 180... from stuart, FL had that arm... i am not sure if anybody else did... also i am wondering what is truck town thunder doign this year.. there was a picture where they showed half of their controller... should i guess that there will be something like a small arm model to control their arm...

http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=6183&direction=DESC&sort=date&perrow=4&trows=3&quiet=Verbose