MWB 4 DOF Simulator

Hi @Nick Moxley, I like what you have done. I may well be pinching you're idea do you know the wattage of you're motors? and how have you found them?

Hi @Blame73, It just so happens, I ordered a couple of hall affect pot's from Farnall after looking at @SilentChill page.

http://uk.farnell.com/bi-technologi...hLookAhead&searchView=table&iscrfnonsku=false

Thanks for the the heads up!

More motor testing

Using Solid Works I started designing my rig.

A lot of the builds on here seem to be using server power supply's, I been testing with a couple of old car battery's and an 11A 24v PSU (£10 from eBay) set to 26v as to trickle charge the battery's when in use and it seems to be ok. Got 1580A cold cranking from the battery's alone ⚡️

@MWB,
Have you tested your design in solidworks to see if it will fall down?
lt doesn't look constrained in all positions.

Batteries are good but how you going to combat over draining and over charging the batteries?

Hi @OZHEAT, yes I tested it in SW, took a bit of mucking around to get everything positioned correctly, but it seems stable now. Fingers crossed.
My thinking on the battery's, is that in a car with the engine running the 12v car battery is allways being charged my the alternator and regulated to 14.6v, so you could say that with two battery's connected in series to get you're 24v you could charge them at 29.2v. This would need to be monitored. I have heard of car batteries exploding due to over charging, but I think the biggest danger is the production of hydrogen.



I don't think this will be a problem for me as I'm only trickle charging the batteries at 26v, I did at one point crank that up to 28v and popped one of my IBT-2 boards (max volt 27v).
See earlier in my thread.
I had been testing for a couple of hours with two motors, the batteries were holding up pretty well still had 12.6 V on both and wasn't charging them at that point.
May need to think about a ventilated box to contain an explosion if something did go wrong, but I think the risk is minimal, also in the video above, the battery cell tops are off, I've got them closed, and in a car the battery's always charging with the cells closed.

Started mounting at couple IBT-2 in a box so that I could also mount fan's on the heatsinks

Also got two motors connected to Dirt Rally via Simtools

Hall affects pots turned up from Farnell today!

This is my my bucket seat, and my metal turned up so I've been busy Busy cutting, grinding, welding, filing. I'll pop up some pics later.

Happy New Year everyone!

Struggling with one of my motors so I decided to clean up the commutator.
Gear box grease is pretty grim!!

In order to get to the commutator, I needed to remove both brushes and modify a flat blade to get the two nuts off.

Then the outer case of the motor could be removed.
The commutator doesn't look to bad.

But I cleaned it up anyway, using my drill and 1200 grit, then 2500 grit.

Had one stubborn score! Little more to come off.

All done!

Just needed to scrape out and crap between the commutator tracks.

Then just a good clean up to get rid of any carbon from the brushes and sand paper. I had buzzed everything out before and after with a ohm meter. Hope this works a little better now! I'll let you know how I get on.

So the motor was I little better, but I still have the same problem, I think it's the IBT-2 motor controller cutting out, its meant to be good for 43A but I have my suspicions its not anywhere near that. I know that @SilentChill thinks there crap? Also in SMC3 if I set PWMmax to max will this unnecessarily over work the controller?

I'm not familiar with how the IBT-2 bridge works, but if you set PWMmax all the way up it's essentially telling your driver to turn the fets 100% on. This will trip the current limiters on the MMs on my sim, so I have mine set to 235, but this is only because my drivers are not large enough to drive the motor at 100% without going over rated current. If your motors stall current is less than the motor drivers maximum you shouldn't be having any problems though.

you can check the stall current of your motors by following this procedure:
https://www.xsimulator.net/community/faq/measuring-motor-stall-current.252/

Hi @Tim McGuire, Thanks for the help!
I think I've worked out the stall current, correct me if I'm wrong!

Measuring the ohms across the motor windings accurately will be impossible with a normal multi meter because the value will be to small so, applying a small voltage across the motor and measuring the current is the way to go, then using ohm law (V/IxR) to calculate the resistance. (Motor shouldn't turn when doing this)

So at 2.9V I got 4A (V/A=R) 2.9/4=0.725

The resistance across my motor windings is 0.725 ohms

Motor is 24v so (V/R=A) 24/0.725=33.10

So if I've done this correctly my stall current is 33.10A

But I'm running the motors at 26V

26/0.725= 35.86A

Cool! That seems like a reasonable value for a 24V motor to have. So I think your drivers should be able to handle it if they really are good for 43A. Do you have loads attached to them yet?

I may need some refinement in my settings to squeeze the most out of my controllers. I think I'm unnecessarily pulling to much current through them.

If that doesn't work, it's mm's! I gather there newer technology than the IBT-2. The power chip looks much bigger.