TreadBot

[dragons_fire]

this is the new robot im working on, the wheels were turned on my busy bee 10x18 and the plastic parts were "milled" on an 8" drill press with a compound vise.

http://i163.photobucket.com/albums/t...o/IMG_7966.jpg
Just a mock-up of the PCB and parts to make sure everything will work where it was designed to work.


http://i163.photobucket.com/albums/t...o/IMG_7965.jpg
Battery installed. its a 7.4V 730mAh li-poly pack.


http://i163.photobucket.com/albums/t...o/IMG_7963.jpg
Wheel detail. wheels roll on dual bearings. magnet for RPM sensor and sensor mounted. as a size reference, those are 4-40 screws.

[ZOB]

Cool stuff , what microcontroller are you using? Just starting to get into pic chips , post more pictures as you progress!

[dragons_fire]

im using a PIC18F6585.

Heres a couple pics of it with the board and components mounted..

the first pic is one of the motors on top of a scroll wheel on my mouse.
http://i163.photobucket.com/albums/t...o/IMG_7988.jpg

Ultrasonic sensor, PIC, SD card reader/writer, and 2-axis accelerometer
http://i163.photobucket.com/albums/t...o/IMG_7995.jpg

front view of ground clearance and ultrasonic sensor
http://i163.photobucket.com/albums/t...o/IMG_7999.jpg

[dbc1218]

Nice compact setup, I like it. What motor controller are you using?

[dragons_fire]

Originally Posted by dbc1218 Nice compact setup, I like it. What motor controller are you using?

im using a Pololu Micro serial motor controller. its supposed to do 2 motors at 1A each. works good, but im having some kind of interference problems that im working on...

[dbc1218]

I have that same controller and a low-voltage dual serial motor controller form pololu as well. Have not used them in a bot yet have a project in the works. I've had some problems with the low-voltage dual serial controller when I used it last. It would be working fine and then just stop the motor, not just turn off and let the motor coast to a stop, the motor would jerk and then it be done. Don't know what it is, tried it on a bunch of motors and it did the same thing. I think I'll be able to use it though.

[dragons_fire]

Originally Posted by dbc1218 It would be working fine and then just stop the motor, not just turn off and let the motor coast to a stop, the motor would jerk and then it be done.

thats exactly my problem, i copied the code out of the book to slowly speed up and then slow down, adn as it gets up to about 1/4 speed, everything just stops. i have an LCD display hooked to my PIC and it keeps counting, so the PIC is still running. when i move the motors out to about 2" away, everything works great, but as soon as i move it close again, it just shuts down.

[dbc1218]

When I did it I was only running one motor with the sample code. I had a bunch of the tamiya size motors, the ones that go in the planetary gearbox, one of them ran fine every time, but the others all did that same thing. I tried a bunch of different capacitors but nothing seemed to work. By the way what type of capacitor are you using on the motors? I might post some thing on pololu's forum, see if I can get some answers.

[dragons_fire]

mine seems to work fine with one motor too... but when i add the second one in, it just freezes... im using 50V .1uF caps....

[keebler303]

It sounds like the motors you are using are too big. Those r/c motors i think will pull a lot more than one amp when you give it the juice. might be something to check before you get too involved in troubleshooting.

Matt

[dragons_fire]

the controller isnt overheating, and im pretty sure the motors arent too big... heres a pic of the motor,
http://i163.photobucket.com/albums/t305/dragons_fire_photo/IMG_7988.jpg and they are rated,
50mA @ 6V, Producing 30.7 oz-in of torque with a stall current of 533ma.
they do draw a little more than 50mA each, but its not too bad... the controller is rated up too 1A for each motor. so maybe it doesnt sense a load on it and its shutting down.. i dont know if it does that, but it could be a possibility...