Custom motor driver for FFB Wheels

Here's an frankenstein hoverboard build. Main obstacle in post before was that it's mount was not good enough. 

Ordered SK16 smooth rod holder and it's freaking great! This mount is way stronger than just taking a clamp directly on motor, like big stepper or mige.

There's one big problem though. My motor's kind of a knockoff. It's stator is half the size of all other hovers...
So very little torque and very much heat.

Other problem is in pulley. One on the motor is drilled and filed to be able to be glued on the motor. Pulley on the encoder as well, needed to make 6mm hole from 5mm. Well, they are both woobly and there's encoder misalignment there. Since motor has 15 poles this is a BIG problem, or at least I think so.

Well for now I think that real motor will be great. Can't be certain about cogging. Other guys here told that there is little cogging, not as good as real servo. Need a 3d printed pulley to print a real mount to the back of the motor.

For now here's a little video of driving. Just ignore all squeaking and noise, it's coming from pedals, chair and fans all around. 
Motor is silent as long as you keep road noise setting in assetto corsa down. At 15% motor Really starts vibrating. But it's good I guess, it should do that if road noise is present.

Here's a picture of step log performance with tyre still on. HILARIOUS (better than actual performance, 20 amps was shoved into the motor expecting to get something out of it. Motor barely handles 4 amps on open air)

This project should be changed to both steppers and servo now :)

Testing was done on 150 Watts 48 V supply, trimmed to 38 V. Strength in Nm should be between 10 and 15, but this is just a guess. Motor is Large Mige 130st-M15015 with 2500 ppr / 10000 cpr encoder.

Didn't reveal stepper electronics yet, but you can see the driver for brushless motors (servos) on the right side. Powered with 2 supplies, one high voltage for motor and other is 12 V Pc power supply.

This is as close as you'll get to OSW without Argon or Ioni. That's why MMOS was used. 10 for effect filters, 0 for overall filter,, no additional effects. 0 on everything in assetto corsa, gain on 100%, 75% in game (to avoid clipping).

Some rally carnage as well, breaking some desks

If anyone ever wondered how would force feedback look on graphs here's a nice representation

MMOS will be tested as well against OpenFFB. This one might get very interesting :)

Smooth Boi enters the game

And with it the support for 3 phase BLDC, AC Servo permanent magnet, Hoverboard, RC Drones, Mige, whatever more name you can think of brushless motors.

This is hoverboard motor btw

Well, all before this was just empty talk without any info on actual strength of the boi. Time for a reveal:

This has been long overdue :)

But finally it's here, testing and driving

Well the title says everything.

Forcefeedback is really good now, compared to what it was before (don't think that it was bad before with 12 Volts power supply, now it's just very good). Everything is snappier and Stronger. Cogging is also reduced because of that new closed loop current control.

Higher voltage gives more headroom for faster rotation. This means that you still get feedback even when counter steering the force from the game. With 12 V, at some point you hit a brick wall and you can't push enough juice into motor to keep FOC running.

This also means that the wheelbase can murder you. Stronk boi is really really fast now and that boi can punch you really hard.

Here are step log results, from wheelcheck

Wheel mounted

No wheel

12V with wheel 

(this chart is flawed, 1080 degrees were in mmos and 900 in wheelcheck, however there is no big change, line may get a little steeper but it won't come close to -5000)

Stay tuned for some stronk boi video action!

Usable force should be about 5 Nm in this moment. Electronics start having a mental breakdown above that level.
This is the reason why wheel started feeling bad at higher forces. Current control is actually very good until 5 Nm. After that there are huge deviations, we are talking about 20 - 40 % difference in expected output vs reality.
Notchiness is still there. I won't even try removing it until full 12.5 Nm are extracted from the wheelbase. Strength is the priority

Edit : The noise in the previous demonstration videos is because of the bad current control. Motor starts squeaking above 5 Nm. If filmed at 5 Nm that there would be no squeaking noise.

Did some Nm testing. At 25% strength wheel was able to lift a 2 liter bottle at 12 cm from center of the shaft. That is about 2.4 Nm. Don't have concrete results yet but that should be about 10 Nm at full strength. For now.

Turns out that bts7960 is not up to the task for closed loop current control. I made another diy bridge and current control now is much better. Current control is still not perfect. But good news is that torque unevenness is much Much better now. Didn't have a lot of time to calibrate it properly. This also solved the problem with fast rotation. Now the strength when steering quickly is not reduced. In fact if I didn't know that the problem existed I'd never notice it.

Notchiness is still there. However below 50% strength or 5 Nm you can only feel the "tip" as a notch. Everything between steps is butter smooth.

Driving with now improved wheel was a blast. Everything below 5 Nm is a meme. It is just not strong enough. 5Nm to 7.5 Nm is good. 7.5 Nm to 10 Nm is really strong. At 7.5 you feel road texture and it is the sweet-spot. More than that and you start struggling to make corrections. But it's too much fun to drive at 10 Nm.

In summary:
- Notchiness got lowered by let's say 70%
- Speedy corrections and rally driving is not reducing strength anymore
- 7.5 Nm is the sweetspot

Flux weakening will be one of the next research steps. It reduces torque and increases power consumption but greatly increases rotational speed. However I'm still not sure if it affects notchiness between steps. If it breaks FOC which is used right now then there's no other solution but to use power supply with more than 12 Volts.