Control System, Joystick mod?

[Jordan A.]

Ive sent to FRC twice now and havnt gotten an awnser, perhaps the question isnt deemed worthy of an awsner or they just havnt gotten to it, either way. We are looking to make a control system thats pretty simple, tank steering with a single joystick. However not the one on the IF web site (its got some issues)

To use our system and avoid trig we would need to rotate the handle of the joystick 45 degrees on its base, it would be reattached and in no way be electrically altered. I read the rules that said alterations to the joystick was not allowed. I was fine with that but then I saw this: http://www.chiefdelphi.com/pics/bin/..._robot_arm.jpg

Does that not count as a joystick mod? and would ours? Or was this is violation of the rules? Some solid awnsers would be nice.

-Jordan

[jonathan lall]

Not remembering (or reading) certain parts of the rules, I'm not sure, and kind of doubt this would be allowed, but the joysticks use standard serial ports, so couldn't you just not use FIRST's sticks altogether?

But wait before you jump for joy; I'm too lazy to read the rules to see, and I highly doubt that you're allowed to use other joysticks (if you think about it, it makes tonnes of sense), especially since you can't alter their sticks. Just a thought, and a way to increase my post count

I wouldn't use that kruddy picture as an argument with a judge, though. Go trig.

[Nate Smith]

Per the AHL, you can use any 15-pin(read: not USB) joystick...and as far as modifying the stick, if i'm reading correctly, you want to take out the 2 screws holding the grip onto the rest of the joystick and rotate it. Unfortunately, with the design of the internal parts of the joystick(mainly the stick that the grip mounts to), there's no easy way to rotate the grip. Why not just create a mount that holds the entire joystick at a 45?

[CaptainPlaid]

It has always been my understanding that control systems are pretty much unlimited. (That's why I work on them I guess, less rules to keep track of) You can basically use anything that is controlled by you that will plug into a 15-pin joystick port. As far as modifiying the CH joysticks I am not sure. However, you can go buy any joystick that is not USB and use that and modify it as you wish. Just make sure the pin outs are the same as the CH or you have to change up the programming.

[bigqueue]

Originally posted by jonathan lall
Not remembering (or reading) certain parts of the rules, I'm not sure, and kind of doubt this would be allowed, but the joysticks use standard serial ports, so couldn't you just not use FIRST's sticks altogether?

How about using the sticks as they are but simply "adding on" your own grip in a way that it slips over the existing one.

The top switch could remain, and the only issue would be with the trigger switch which would have to be fabricated into the new grip.

Heck..just use potentiometers and make a joystick from scratch from wood.

There are many ways to skin the cat.

-Quentin

[Jordan A.]

Some good ideas thanks.

Nate, that could happen but then the driver would have to twist* his wrist 45 degrees and that would be uncomfortable.

We want to cut the base of the stick itself, and rotate and re attach.

Basically if you rotate it and assign each side to an axis it works out a perfectly for single joystick tank steering. Only problem is it can be a bit sensitive, but we can fix that with some slow zone in the center.

*edit: I was caught by the censor, apprently I used a bad word (ill give you a hint it rhymes with bock)

[Greg McCoy]

Are you sure that you can't do what you want to do in the software without trig?

[Jordan A.]

Greg, pretty sure. We drew out a chart for our math teacher and asked him if he could find a formula but he couldnt, and this is a guy who has his masters in mathematics from the University of Waterloo...

[bigqueue]

Originally posted by Jordan A.
Greg, pretty sure. We drew out a chart for our math teacher and asked him if he could find a formula but he couldnt, and this is a guy who has his masters in mathematics from the University of Waterloo...

I might be missing something, so please disregard this should I be in left field.

Have you looked at the white paper on the Innovation First website?

Look at this and see if it helps:

One Joystick Tank Drive Whitepaper
http://www.innovationfirst.com/FIRST...ickControl.pdf

Good luck,
-Quentin

[Greg McCoy]

Yeah, I think our team was trying something similar to that out, and I think it works pretty well. I haven't been working on the software a whole lot lately though, so I may be way off too.

[bigqueue]

Originally posted by Greg McCoy
Yeah, I think our team was trying something similar to that out, and I think it works pretty well. I haven't been working on the software a whole lot lately though, so I may be way off too.

Oh, we tried it and ot works fine.....it's just that our "chosen drivers" are two-stick people (as opposed to the coder who is a "one-stick" guy)...so we will NOT be using it.

-Quentin

[Adam Krajewski]

Constants are a blessing. It's often easier to use a look-up table of values than to try and do complex calculations on-board. And even if you could, factors such as mechanical imperfections (it's never a programming problem ) render perfect theoretical calculations imprecise in actual practice.

Adam

[Jordan A.]

Quentin, I mentioned in my origional post about the Innovation First program but I said IF

I talked to our driver today and he was totaly planning on using two so it shouldnt be an issue.

Still was a fun concept to play with.

[Greg McCoy]

What's wrong with the Innovation First code? As far as I know it works fine. Even ironing out some bugs would be way easier than taking joysticks apart and doing it differently with your own code. I don't understand how that would help anyway.

[Wayne Doenges]

According to the rules last year you couldn't modify the joysticks. Team 234 should have been told that they had to change there control.
Someone on Team 234 said that they "held their breath" everytime a judge stopped by. But they won the innovation awards, so it must have been legal.
We would like to use a glove to control part of our robot but some of the things we want to use are not in the AHL. But than again, I didn't see a backpack listed last year.
We can't get FIRST to give us a good answer and we don't want to "hold our breath" when a judge walks by.

Wayne Doenges