Central High Robotics Team Forum

[the_lies_they_tell]

I want to get this started asap for a few reasons A. it's something to do, B. if it's done now then thats one less thing to worry about when we get deep into robot construction, and C. any freshman members can find out a bit about electronics before we actually do the wiring for the bot.
If the ordering deadline is Wednesday, I kinda need to have a basic plan for it. If you guys give me what you need on it I can do the design.

by the way, are we just goin for the basic lexan sandwich board or are we actually gonna do somethin new?
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Bryant
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Everything burns.....eventually.

[Kronos]

Well, there's that thing from last year...there's a mechanism that contains 3 switches wired to it that allows you to select from 8 different autonomous modes...tha might be useful if you want to select from 8 of anything...autonomous modes, driver configurations (different drivers have different control preferences), and so on. There's also the dealy that has a 3-way switch on it (useful for controlling, oh I don't know...a forklift?)
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Eugene - Robotics Alumnus
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[the_lies_they_tell]

well because we're using the x-box controller, those drive config switches might be handy. But as far as the 3-state switch goes, i don't think we can use that because the arm "forklift" is gonna be raised and lowered to different heights as needed, not all the way up or down.

As far as design goes, I was thinkin of doin a batwing type thing w/ black lexan.
_________________
Bryant
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Everything burns.....eventually.

[Kronos]

No, no, that's not what the 3-way switch is for. The 3-way switch has 3 positions: up, off, or down. This controls whether the forklift should move up, not at all, or down, not where the forklift should be. You can still stop the forklift at any position. I do not know whether we need the forklift to move at variable speeds or not. I do not know whether it is desired that the forklift be able to move down quickly as well as slowly and not just at some medium constant speed. In that case, the forklift would have to be controlled by a joystick or some similar device. I think it should just be up, still, or down since that would make it easier to control, but this is open to debate. Anyone care to chime in with an opinion?

Oh, and what's this thing about using an X-box controller? Who thought of that? I personally don't think it's a good idea. Big joysticks allow for more precise control. Just because we're allowed to use an X-box controller doesn't mean we should. Then again, the drivers may be already very comfortable with an X-box controller. Anyone care to tell me how exactly the robot will be controlled with an X-box controller?
_________________
Eugene - Robotics Alumnus
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Moebius strip no-wear belt drive! (Please see other side for warranty details.)
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God is real, unless declared integer.

[the_lies_they_tell]

Well theres basically an adapter that plugs into the joystick port and allows the use of any usb controller or gamepad. The x-box controller, i suppose, would be programmed and calibrated the same as the joystick. Also if all of the buttons on the controller are programmable then no extra buttons on the control board would be necessary.
_________________
Bryant
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Everything burns.....eventually.

[Kronos]

How exactly do you control a tank drive with an X-box controller? What's the actual control scheme here? Also, I really doubt that every button will be programmable...and my doubts are based in knowledge of the structure of the Operator Interface. You should find appropriate documentation on this and resolve such issues before you make any fancy plans as to what you will do with the X-box controller. Find out which buttons are programmable.
_________________
Eugene - Robotics Alumnus
******
Moebius strip no-wear belt drive! (Please see other side for warranty details.)
******
God is real, unless declared integer.

[the_lies_they_tell]

well seeing as how there are two joysticks on the x-box controller that would basically be used to drive the tank drive in exactly the same way that the two indeendent jysticks would drive it, I don't see that as a problem. Also the usb version of the controller is also certified as a plug and play computer gamepad so 'm pretty sure that most if not all of the buttons can have functions assigned to them. On top of theis, because I'm starting the control board now, if we find that for whatever resn we can't use the x-box controller then it would be a simle matter of plugging in the joysticks...
_________________
Bryant
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Everything burns.....eventually.

[Kronos]

Okay. So here's the difficulty that I perceive. The two joysticks on the X-box controller are positioned much closer together than on the two-separate joystick setup. They are also not as big, and therefore control is not nearly as precise as before. If before you could go from the robot not moving to 5% motor power by a little push of the joystick, now that push will be like 30% motor power. I have a feeling a robot might be hard to control with this setup, and you won't know until you actually have a robot to control.

All of this is not really a problem, because you can switch back to the old-fashioned 2-joystick control very easily. Just make sure you have 2 joysticks handy at the competition (and the code for it!), unless you get a chance to test the robot driving extensively before that.

Now, about all the buttons working or not working...my hypothesis that not all buttons will be functional is based on actual knowledge of the architecture of the Operator Interface and not just pulled out of thin air. Unless I'm mistaken, the adapter connects to your controller and then to the set of 15 pins on the Operator Interface. That's what it adapts between. Now, the way the pins work is that 4 of them (somewhere, you can find which ones) are digital signals, meaning that they can carry a signal of either 0 or 1 (0 volts or 5 volts). These are used for buttons. This only allows for 4 buttons to be functional. There is some way to get 8 of the pins to carry digital signals on some but not all of the ports (ports 2 and 4, perhaps). So it may be that 8 buttons will be functional, but you might not know which ones and how to get this to work until you read the documentation.

Perhaps there are some settings that you need to change to make the controllers work that you won't know about until you have a working robot. Perhaps you'll test it and it'll work fine until you add the arm mechanism. You don't want to be trying to fix this the day before ship date.

Please, read the documentation BEFORE DOING ANYTHING. Trust me, ever since 1999 (the year our school first did Robotics, and I wasn't even here then), saying "I'll do this by guessing and then have time to fix it if it doesn't work" has been a quick route to failure. You need to hit it dead on and get it right the first time.

Wow, that was a long post.
_________________
Eugene - Robotics Alumnus
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Moebius strip no-wear belt drive! (Please see other side for warranty details.)
******
God is real, unless declared integer.

[the_lies_they_tell]

Well I've been back and forth through the adapter manual and it appears that there are modes that can be chosen and each mode activates a different set of buttons along with different axis being assigned to the joysticks on the controller. seeing as we only need about three buttons i think that we'll be fine, if not we switch to classic controllers, no big deal
_________________
Bryant
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Everything burns.....eventually.

[Kronos]

Alright, sounds good. As long as it is convenient to control
_________________
Eugene - Robotics Alumnus
******
Moebius strip no-wear belt drive! (Please see other side for warranty details.)
******
God is real, unless declared integer.