TreadBot

[dragons_fire]

when i first started building this, my intention was to put the battery between the 2 motors inside the red fibreglass. because i wanted lots of capacity, and a higher voltage, i added them to the top. so now i have lots of room insid the chassis.

i will probably make tubes to go around the motors, and hopefully that will help.

I might also cast a lead "brick" to fill in the space between them to make it a little more stable on angles, and for more grip. the only problem is that i will lose some endurance because the motors will need to haul more wieght.

ive been working for the last ten days, but i get the next 4 off, and its raining like crazy here, so i should get some time this weekend to play with it a bit more.

After i get the "interference" problem figured out, i will have a video up here of it driving around. i have written the code for it to speed up, drive, sense obsactles, slow down and then turn and drive that way..

[skimask]

when i first started building this, my intention was to put the battery between the 2 motors inside the red fibreglass. because i wanted lots of capacity, and a higher voltage, i added them to the top. so now i have lots of room insid the chassis.
i will probably make tubes to go around the motors, and hopefully that will help.
I might also cast a lead "brick" to fill in the space between them to make it a little more stable on angles, and for more grip. the only problem is that i will lose some endurance because the motors will need to haul more wieght.
ive been working for the last ten days, but i get the next 4 off, and its raining like crazy here, so i should get some time this weekend to play with it a bit more.
After i get the "interference" problem figured out, i will have a video up here of it driving around. i have written the code for it to speed up, drive, sense obsactles, slow down and then turn and drive that way..

It was recently (today) suggested in another thread talking about unused pins and running motors and getting interference, etc., to occassionally reaffirm your TRIS assignments for all the pins you're using.

In other words, every once in awhile, or whenever you can spare a cycle or two, redo all your TRIS's, keep your inputs as inputs, and your outputs as outputs.

It seemed to help this other person's problem with motors, magnetics, etc., and it's only a slight software change.
Might help you too...

[dragons_fire]

well, i just noticed that thread as you were replying.. i will give it a try when i get home... the motor controller has a reset line on it that needs to be held high, so i used a pin from the pic, so i can turn it on or off if i need too, and i think hte pic is probably going low on that pin..

do i want to make all the unused (almost all of them right now) inputs or outputs?? they arent tied to ground or anything, because they will eventually be used.

and im not too worried about program space (yet), i have 24K words, and im only using about 300 words right now... i would prefer to get rid of as much magnetism and electrical noise as possible by physical means, and not just block it out with programming..

thanks for the help guys

[skimask]

the motor controller has a reset line on it that needs to be held high, so i used a pin from the pic, so i can turn it on or off if i need too, and i think hte pic is probably going low on that pin

Good idea...keep pinging that pin in your program to help force it high if need be.

do i want to make all the unused (almost all of them right now) inputs or outputs?? they arent tied to ground or anything, because they will eventually be used.

Don't really know on that. Almost anyone of them could be causing a problem. One thing is almost for sure though, if a pin is an output, it generally can't cause an interrupt.

i would prefer to get rid of as much magnetism and electrical noise as possible by physical means, and not just block it out with programming..

But the extra programming doesn't cost anything in hardware!

[SteveB]

well, i just noticed that thread as you were replying.. i will give it a try when i get home... the motor controller has a reset line on it that needs to be held high, so i used a pin from the pic, so i can turn it on or off if i need too, and i think hte pic is probably going low on that pin..

You could also try using a pull-up, and keeping the pin as input. If you want a reset, then in the program change it to an output, low, pause as needed, high, then back to input.

[dragons_fire]

i dont really know whats going on... ive been playing with it for a bit this weekend, and something funny is going on..

when i hold the board about 2" above the motors, everything works fine, if its closer, it will start to speed up, and then just completely stop, and wont reset.

if i plug in my serial LCD and keep the board 2" away from the motors, they run fine, but the LCD will work for a bit, then go blank, and then work a bit more, and go blank and then work more.

with the board beside the motors, the LCd will start, go all black, and then come back and the motors will stop. then the lcd will keep displaying the speed variable changing, so somewhere in there, i think the motor reset is being tripped and its not restarting.

heres a tiny bit of my code...





baudLCD CON 32 'baud rate for lcd
lcd VAR PORTF.0 'serial lcd port
motor VAR PORTD.0 'serial motor port
motorreset VAR PORTE.7 'reset pin For motor controller
baudmotor CON 84 'baud rate for motor
LBAK CON 1 'left backwards
LFWD CON 0 'left forwards
RBAK CON 3 'right backwards
RFWD CON 2 'right forward
speed VAR BYTE



start:

High lcd
High motor
High motorreset

SerOut2 lcd, baudlcd,[254,"G",1,1,"Treadbot"] 'display treadbot on lcd in position 1,1

Pause 1000

For speed = 0 TO 80 'speed up motor to full speed
SerOut2 lcd, baudlcd,[254,"G",1,4,#speed," "] 'display speed var on lcd in position 1,4
SerOut2 motor, baudmotor, [$80, 0, lfwd, speed] 'left motor forward
SerOut2 motor, baudmotor, [$80, 0, rfwd, speed] 'right motor forward
Pause 150
Next

Pause 10000
'drive at full speed for 10 sec
For speed = 80 TO 1 STEP - 1 'slow down motor until stop
SerOut2 lcd, baudlcd,[254,"G",1,4,#speed," "] 'display speed var on LCD in position 1.4
SerOut2 motor, baudmotor, [$80, 0, lfwd, speed] 'left motor forward
SerOut2 motor, baudmotor, [$80, 0, rfwd, speed] 'right motor forward
Pause 150
Next

[JohnH]

I built a walking (biped) robot and had trouble with motor noise causing the A/D signals to vary. (I use two A/D inputs to read pots coupled to the legs for position information.) Adding .1uf caps from each motor lead to the motor's case solved the problem.

My motors are the cheaper hobby motors used with the Tamiya double gearbox. If you are using the Pololu serial motor controller they recommend the caps too. I use an analog H bridge and still had noise issues even with seperate motor and logic batteries.

I don't know if it will help you but it is something to try....

By the way, you did an excellent job on the project, I hope it works out.
--John

[dragons_fire]

thanks for the compliment John, i have added the caps across one motor, and just forgot about the other motor. i usually add one from each lead to the case, and another across both leads. its one of those things i picked up from RC cars and planes.

heres a picture of one of my motors ontop of the scroll wheel on my mouse. i cant remeber if i posted it before, but here it is again..



i would like to see a pic of that biped if you have any.. its one thing i want to do eventually. heres a hexapod i made, its kinda the same as the Lynxmotion hexapod.