Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: BANE on February 23, 2008, 09:20:03 PM
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hello, i need some help and advise on making a mill controller. I'm using three 12vdc motors (small mill) and want to control them using a joystick I got out of a airplane controller (two potentiometers, X & Y). Everything is going to analog and farley simple. I want to have to motors speeds vary on how far the joy is pushed. I'm guessing that i would have a series of transistors and diodes or H-bridge. I can make to pots control the motors in only one direction. I need help on how to make it where i get control both directions and proportional speeds.
check out pics ;)
bane
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well with a microcontroller you would take an ADC of the joystick pots, and generate a PWM to the H bridge based on the resistance of the pots
Like if the ADC was 122 ( of an 8 bit conversion) thats halfway so you would give a PWM of 50%
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I'm trying to build something simular to this, only use my joy instead.
http://www.hobbyengineering.com/CatEKMOT.html (http://www.hobbyengineering.com/CatEKMOT.html)
any idea what the schematics might look like?
bane
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I'm trying to build something simular to this, only use my joy instead.
http://www.hobbyengineering.com/CatEKMOT.html (http://www.hobbyengineering.com/CatEKMOT.html)
any idea what the schematics might look like?
bane
http://info.hobbyengineering.com/specs/DIY-k166.pdf (http://info.hobbyengineering.com/specs/DIY-k166.pdf)
datasheets man! Its all in there
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ha, just as you posted that i just came back to say i found it! :D. only it was a different website
thanks!
bane
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You know the more I look into this, it would be cheaper and easier to use my microcontroller and a H-bridge :D
bane
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You know the more I look into this, it would be cheaper and easier to use my microcontroller and a H-bridge :D
bane
hmmm that sounds familiar ;)
well with a microcontroller you would take an ADC of the joystick pots, and generate a PWM to the H bridge based on the resistance of the \
and it would be cheaper
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2 servo's man. replace the pots of the servo with the joystick and solder your motors on instead of the old ones. you still might need to use transistors/mosfets to beef up the controller board
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2 servo's man. replace the pots of the servo with the joystick and solder your motors on instead of the old ones. you still might need to use transistors/mosfets to beef up the controller board
sounds good .... in theory
the pots would have to match and there might be other problems that will pop into my head tomorrow
good night US east coast! ;)
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So if that would work, i would have to modify the servo to handle 9.6v or does it matter since im replacing the motors?
Another thing, I would have to generate a pulse simular to what a microcontroller would do only with out it.
bane
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the circuit in the servo can only hold up to 7.2V ( really supposed to be 6V)
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I know, but can you modify it?
bane
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I would stick to using motors personally, ideally stepper motors. You would need a controller mcu to use it properly but it would mean that you can work on making it computer controlled at a later date without having to setup encoder etc..
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I have three stepping motors I got from a print/scanner. I guess its worth a shot, however, the motors that i got only have 4 pins, most of the stepping controllers that i've seen require at least 5 pins..... any ideas? I have a microcontroller and if I could get three stepper controllers it wouldn't be to hard to make. Just a thought, i have the BOT BOARD II w/ BASIC ATOM 28 pin, I could even control it using a PS2 controller... sweet!
any suggestions where to get three cheap stepping motor controllers (4 pin)?
bane
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those are bipolar motors.
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a lot of normal motor full-bridge ic's can control stepper motors. Also you can use darlington driver ic's or just h-bridge type set up with mosfets. Its better to build your own than buy an expensive driver
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is this the type?
http://www.hobbyengineering.com/H1143.html (http://www.hobbyengineering.com/H1143.html)
if so, they seem pretty cheap to me :D
But, no idea how the schematics would look. :-\
bane
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i just found this.
http://www.electronicsinschools.org/page.php?ps=2&p=11 (http://www.electronicsinschools.org/page.php?ps=2&p=11)
i still don't know how to set it up to control a bi-polar using microcontroller though.
bane
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the uln 2003 seem ideal. I'll see if i can find a diagram for using it with a stepper motor, i saw one last week.
You will probably need one of the darlington arrays for each stepper. They are easy to use with a microcontroller
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Thanks, i would appreciate it :). He is a pic i found google, i'm guessing i'd make something similar.
(http://bono02.files.wordpress.com/2007/07/stepperx.jpg)
bane
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I'd recommend using potentiometers with knobs instead of your joystick idea.
This way you can get much easier and more precise/repeatable control over the motion.
Easier to interface, too.
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Well I was thinking that i would use the joy with a microcontroller to operate. I would have the microcontroller control the H-bridges. I don't know much on getting the microcontroller to take direct readings from a pot, but i know theres code for the PS2 joy. Besides, i think it would be fun. :D
bane
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it would be simple analog to digital conversion for the pot
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but wouldn't that mean that I would have to get some kind of convertor of some sort = $$$$. PS2 controller = $20.00
i have to amit, i dont know to much about this but it seems more logical to me :\
bane
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microcontrollers have built in analog to digital ,no extra $$$ needed