Classic 2 Dof - Stuck with electronics!! argh

Hi All

My first proper post, just wanted to give a brief intro and say a huge thank you to everyone contributing to this great site as building a motion platform has been a dream for many years.
The potential in VR (have bought rift DK1 and 2 and looking forward to VIVE and CV1) and the fact that i moved to a bigger house last year has finally made it the right time for me to look at this properly.

last project was a virtual pinball cab (widebody williams replica) with 47 inch screen, shaker motor, contactors for force feedback, Cree lighting and all the works.



After soldering and wiring this rats nest i thought an audrino and MM 2 dof sim seemed straight forward enough but despite reading a ton of posts and spending a ton of time trying different board and wiring combo's i cant seem to get the basic electronics up and running here.

i started sourcing parts around xmas time so was lucky enough to grab a couple of motion dynamics 12v dc motors with 60:1 boxes whilst they were still on UK ebay.
other than that i have:

modified HP DPS-600PB PSU's
Arduino Uno R3
MotoMonsters
Bourn Pots 6639: 5kohm 1W continuous turn 340 degree

Current wiring config as per linked H bridge guide, soldering not perfect but acceptable i think:



Power light on MM working but no output voltage on A1/B1 and A2/B2
Motors are working when connected directly to PSU so no prob there but for some reason i cant get any motion through ard and MM at the moment.
Have uploaded SMC3 code and set to correct port.
Win 7 port settings: BPS: 115200, bits: 8, parity: none, Stopbits: 1, Flow contrl: None

Feeback reading in SM3utils seems to have a mind of its own with a sine like reading and turning pot does nothing.



Have tried multiple MM's and also ordered another official Ard incase that was the issue. No movement with any of em.
I thinking maybe i have the wrong pots or judging by all the issues people are having with the MM's my 4 samples are all knackered.

If anyone has any suggestions about why i cant get motion then this would be greatly appreciated as its getting very frustrating and ive about run out of ideas.

Many Thanks, Paul.

A picture tells a thousand words , or a video of your wiring and setup. Just to make sure you have it all wired correctly.

From your list it looks like it should work fine and out of 4 MM's you would of got some kind of movent on at least half of the board in one direction. Although i did have 3 which were totally DOA out of 12.

Yep Sorry have the images issue sorted

The MM in the pic has not been connected to a motor yet hence no heat sinks. Im guessing i should still get a voltage reading from A/B when manually turning pot.

Your pot feedback needs to go straight to the Uno and then from the uno to the MM


edit: sorry its the picture i thought it was going straight to the MM but the brown wires goes down into pin9

Yep, ive checked the wiring over and over and solder/checked all 4 MM's i have... pretty damn sure its all correct.

Im sure im being dumb somewhere but im stumped at the minute.

The pot instructions have no indication of what is neg/pos etc on term 1,2 and 3.
does it matter what goes where? ive tried several combinations and have voltage going to pot but not sure if it might be causing an issue.

Ok in SMC util you need to set it to 20hz and raise your max limits to 150 or so, put PWMin to 0 and PWM Rev to 0 and I would set PWMmax to about 150 to start with. And then reverse polarity on your motor see how that does May do nothing but worth a try

@paulg100 when feedback gets out of range SMC3 disables motors for protection. your motors are all off. get your pot at the middle point and then press the off button to make it on again so you can have motion again.





and your interface settings should look like this with different com port com9 from your pic


and for your pots you should refer you seller or if you have a multimeter take some mesurements to find the "runner" usually its the middle pin

Yes it does !!! take a picture of your pot looking at the pins normally the top 2 close together are for power and the feedback is the bottom one like at the bottom of a traingle

top 2 pins are for power the bottom one is the feedback pin. Pin 1 is Ground Pin 2 Is output and Pin3 is positive

Great big thanks for the quick reply's guys,

will have a quick play around before bed and report back tomorrow,

If it works let us know before you go to bed else I wont sleep tonight worrying

Ha @SilentChill i think your having enough sleepless nights worrying about your own 6dof by the looks of it!! great project btw.
this 2dof is a trial to move on to a 6dof after, maybe the AC, VFD route we will see..

Anyway, SUCCESS!!
Everything was leading me back to the pots as they had a mind of their own with no control no matter which way i wired them..
So i was passing a maplins earlier (rip off prices i know!) and stopped by and picked up a cheap 10k pot to try.
Hooked it up and BINGO, everything is working.
Sooo.. the pots i bought are not suitable, or damaged from miss wiring?

So i need to order a couple of quality suitable pots, i did a fair bit of searching before buying the ones i did but there seems to be many different
ones everyone is using,
Can anyone recommend a suitable pot (UK availability) that is knowen to work well? not to bothered about the price as long as they work properly.

cant believe the amount of wasted time and head scratching ive done due to these damn pots! Thanks for the help so far.

@paulg100 good to hear you got things working.

from FAQ's

http://www.newark.com/webapp/wcs/st...d=10194&st=6127V&pageSize=25&showResults=true

and from farnell http://uk.farnell.com/webapp/wcs/st...5001&langId=44&storeId=10151&gs=true&st=6127V

OK great, thanks for the how to link, must of missed that one.

thanks for the help all, now on with the build until the next road block

I recommend the hall effect pots they work really well not had one fail in 9 months. They aren't that expensive either.

OK thanks will order some 10k hall effects today