How to get rid of cogging in recon filters below 8?

Simucube 1
1

I have small MiGe SC1 with Biss-C encoder.

Was playing around with the recon filter in the software to bring a little more ‘bump’ to my racing - mostly iRacing.
I recall MMOS never feeling like this, and that was with my original 10K encoder.
I’ve heard that recon 1 or off should be about the same as MMOs, but anything below recon 8, the notchiness/cogging turning the wheel is bad - you can really feel it.

2

Sounds like you have wrong encoder settings to me.

Never run recon at off unless you want your wheel to feel like crap.
In fact anything below about 5 on the newer Simucube software I do not think it feels as good.

Many many people have settled at 8 on the recon as best setting.

3

mmos was exactly the same. if you dont wanna feel the hacksaw feel of the ffb signal rate especially in iracing u need rcon 8 or 9. but its the same for a 360hz signal imho you never wanna get below rcon 8.

nothing to do with encoder settings. thats just how it is.

4

Recon 8, wow, iRacing signal must be really bad.

5

doesn’t matter which signal. welcome to the real world :smiley:

6

Never used anything above 1, no cogging just more details.
But this is SC2 and AC, apples to oranges.
Wth Mmos on Argon had overall filter at 4% max.
I understand that some may prefer glass smooth feedback, matter of taste, but recon 8 just to get rid of cogging sounds like an overkill and perhaps an indication that something is not right.

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7

not apples and oranges sc2 rcon filter is exactly the same. also got feedback from friends with sc2 u need rcon 8 minimum. otherwise udrive with a hacksaw.

its not overkill people are just used too bad feedback thinking its details but its not.

8

Details and cogging are not the same thing.
Recon 8 kills both.

9

You dont lose any details with rcon 8, rcon 1 is way to low and you feel the ffb signal teeth cogs wathever you wanna call it. it doesnt matter if the game is 360hz ffb or even more rcon1 is unusable. and has nothing to do with how ffb should feel or realism. ( oke some people are used to it and like it but that doesn’t mean they are right or know what they are doing) there are so many people driving tottally crooked settings

where do i say the cogging and detail is the same thing i totally don’t say that.

here i explain it all. and it doesn’t only apply to iracing only. its the same for any race sim also rf2 with 360hz ffb only its less obvious. https://www.youtube.com/watch?v=0KFEn6QB_0o

10

Let me disagree on that and move on.

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11

I have been on recon 9 for a long time and never had the desire to turn it down again.

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12

With the SC1 / SinCos, I have Recon at 8 for most titles.

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13

image

These are my SC1 settings for a Kollmorgen 54K with a Henglster Ad58 Biss encoder at 4.2M. Buttery smooth and no cogging, lots of detail. I have also tuned in the cogging compensation in grantiy, which you can quite easily do outside of game, just follow the instructions in the granity docs.

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14

Nice! I wonder if that’s because of your motor vs the MiGe?

I guess I probably forgot about the cogging as I was too amazed by everything else when first moving to DD wheel?!

No worries!

15

Could be, I went straight to the Kollmorgen when I went Simucube, and I’ve never tried a Mige build so I have no reference point. I do think that a lot of people skip the cogging and ripple compensation step in granity though, which makes a massive difference. If I slowly turn my wheel powered on but not in game, its absolutely smooth, with no notches. Seriously, I would highly recommend everyone take the time to do a cogging compensation pass in granity, it’s really easy and made a big difference for me.

16

For you, it may be easy but, it’s looks like learning a whole new language. I looked at the guide but, I’m lost already. Detecting the cog’s in step-1 yields pretty vague results and how am I to determine the number of poles?

17

@smilen - perhaps you could post a quick link to whatever tutorial/guide on how to do this ‘cogging compensation pass’ in Granity?
That would be really cool to try out!
PM me if you don’t feel like posting on here, but I’m sure many would love to experiment with it.
Thanks!

18

Sure - the guide I used is this: https://granitedevices.com/wiki/Configuring_cogging_torque_compensation
It’s the same guide that shows up on the tuning page when using granity.
Pole count depends on motor - which hopefully you have already configured correctly in granity. You can find that under the MPC setting of the Machine tab in granity (under Motor Paramaters). It should also be listed in your servo motors specifications. It is possible to determine it manually using this method: https://granitedevices.com/wiki/Determining_motor_pole_count
Small and large Mige have a pole count of 8.

Once you know the pole count follow this procedure;

  1. Press in the emergency stop (to disable all power to the motor)
  2. Align your steering wheel to resting position (basically straight - it doesn’t really matter where you start, as long as you know when you get back to that position)
  3. Slowly rotate the wheel, you’ll feel a notch (or step) every slight turn
  4. Count the number of notches as you continue to turn the wheel until you end up where you started (360 degrees)
  5. Divide the step count above by your pole count, and then multiply that by two
  6. For example lets say a small mige had 24 steps; 24/8(pole Count) = 3, Multiply 3 by 2 = 6. 6 is our N value for the TRF1 function
  7. Set TRF1 to Sin(Nx), (In our example above, Sin(6x))
  8. Release the emergency stop (motor now has power)
  9. Set TRA1 to 0.1 and rotate the wheel slowly, still feel cogging? Increase by 0.1
  10. Keep increasing until you feel cogging reduce, then increase again, when that happens reduce by 0.05, fine tune from there
  11. If cogging does not reduce, repeat procedure with negative values, start at -0.1, then -0.2, once you find the setting with least cogging, fine tune in 0.05 increments
  12. Once you find the value that has the least cogging (is as smooth as possible), switch TRA1 to Cos(6x) - (remember 6 is just an example value)
  13. Try with a positive and negative Cos using the value that was smoothest on Sin (or repeat entire procedure)
  14. Pick either Sin or Cos based on whichever is smoothest

Once complete you should be able to rotate the wheel when it is powered on and feel little to no notching in the wheel, it should be very smooth.
You can repeat this procedure for Ripple Compensation - just set a target setpoint (TSP1) and hit SetAbs, this will put the motor under torque (don’t set it too high!). Hold the wheel still under this torque and slowly turn - if you feel any notching (ripple), tune it out using the same procedure as for cogging. On my kollmorgen I was unable to feel any ripple, so ended up not using ripple compensation. I ended up with Sin(12x) and -0.13A as my cogging compensation function (iirc). It will be different for different motors (even of the same brand/model).

Hopefully that’s helpful to some - honestly I’ve just paraphrased the documentation that’s already there, but maybe with specific concrete examples it’s a little more accessible!

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19

Thank you for the detailed explanation. I’ll give it a try and see how it compares.

20

thank you for posting this!