Sim Racing servo ffb systems : OSW & Bodnar

nice. Can you link the thread (again) please.

 

Regarding rpm, power, etc. what are your thoughts about the following:

Regarding some other concerns:
Ok, so unless I misunderstood you, all MiGe simracers, regardless of model, are limited to no greater than 300 rpm? If so then the goal for the maximum potential is to have tour desired peak torque @ 300 rpm, correct?

With regards to your #3:
Can you use the IONI but just use a better PSU and then be able to achieve 30 Nm @ 300 rpm?

P.S. I didn't realize the "big" and "medium" MiGes required more power than the "small" when running at the same peak torque... Great to know, thanks.

 

Regardless of the answer to that question, is it necessary?

You don't need 30Nm to keep the free wheel turning 5 times/second, and the chances of you noticing the difference between (say) 10Nm and 30Nm when you're either 1) catching the wheel at that speed, or 2) still trying to hold onto the wheel at that speed, seem minimal. (note: I don't think 2 would happen)

It really is easy to get so caught up in numbers that you lose focus on the application. 300rpm is still overkill, which is presumably why it's been set as the limit. Not a "that'll do for now" limit, but a "we're simulating a car steering wheel, there is no need for more".

 

But 300 rpm can only be for 0.1 seconds or something. It's basically to have quicker and more powerful speeds for very short reactions and twitches and stuff for more FFB accuracy and detail. I don't care if my wheel does or does not do full rotations at 300 rpm, I'm not looking to chop my fingers off but 300 rpm for 0.1 of a second or whatever is a different story, I'd imagine.

I'm going to be ordering one soon. All yesterday I thought the "medium-small" MiGe was easily the winner. Then this morning it looked like it was better to just go for the "big". But now it seems like the "small" is best because A. we're all limited to 300 rpm (regardless of MiGe model) and B. at any given peak torque and rpm (e.g. 30 Nm @ 100 rpm) the "small" MiGe is actually easier to power (requires less power to achieve the same torque and rpm) than the "mediums" and the "big".

So I thought I finally had my mind made up 3 different times in the past 24 hours, lol.

 

I'm curious about this 300 RPM soft-cap. Led, what is the purpose of going with the argon over IONI then?

So, I just found out that the bodnar is actually powered by nothing more than a 48V, 10A, 480W output psu which means peak rpm at the same 13Nm limit of the AF Pro is only twice as fast as what the AF Pro can sustain 13Nm at. I'm thinking now that whilst RPM played a role in the observed difference (e.g. in the comparison vid...neglecting the profile/setting issues that were found on the AF), it's in combination with the difference in peak torque that was why the bodnar/osw ffb felt more distinct and responsive for those comparing (i.e. the bodnar and OSW's are driven more powerfully).

When he puts it like that, you may as well go with the small. It'll actually be more efficient too since the mediums are designed to have higher rated speeds but to achieve that they had to have the stator winding wire thicknesses increased. That means for the same volume of space to play with, they had to decrease the number of winding loops which decreases the magentic field strength potential for the same amount of current. So to boost the magnetic field strength back up to match the 10Nm rating, the motor requires more current hence the lower (i.e. less efficient) torque coefficient (Nm/A) values with the bigger motors. But as Led explained well, you're never going to need to attain these speeds nor want to, even the small mige's 1000 RPM is nuts for sim use. I think you'll be more than happy with 27.5Nm peak torque with IONI + small mige as well.

So with IONI (@600W...25% more than bodnar's) and small mige, 10Nm can be sustained for up to 6.3 Rev/s (378 RPM). 20Nm will be 3.1 Rev/s (189 RPM) and 27.5Nm 2.3 rev/s (137 RPM).

Yeah, my bad, lol.

And thanks for shedding light on all this Led.

Edit: Actually, IONI can take up to 52V and 15A which is pretty massive 780W. With 15A limit, you can drive the mige all the way up to 33Nm, lol. Peak sustainable speed at that would be 2.5 rev/s (149 RPM).

But whether it's safe to do so...know anyone who's ran/running their small mige's to 33Nm?

 

There's a lot of misinformation in this thread. No time to correct everything, but here are two points:

- 300 rpm is already way overkill, even for a crash. Think about it, that's 5x 360 degrees in a second. Or basically full lock (900 degrees) in half a second. However, you can set it higher in Granity if you really want it.

- The current used in the IONI and in the Argon is measured in peak of sine. The torque constant used in the motors however is in rms (root mean square). So you need to take the current of the IONI/Argon and divide it by 1.414 before you multiply it with the torque constant of the motor to get your maximum torque value.

 

Yes but don't you need those high torque / high rpm capabilities for fractions of a second? For e.g. 300 rpm for 0.1 sec? Isn't that part of what is needed in order to be able to output as much FFB quality/detail and fidelity as possible?

Great, so we're back to "square 1".

 

Yes, of course it is. I was referring to another post here, stating that you need to reach 1500rpm for the sim to feel realistic. That statement is completely wrong. The sweet spot for a realistic maximum rotation speed is somewhere between 300 and 400 rpm. 400 rpm being in my opinion already unrealistically fast.

By the way, one of the reasons why a stepper motor sort of makes sense for simracing, is the fact that we don't want the high rpm, that servo motors are capable of. That said, the speed of the Accuforce seems to be too low (comparable to a CSW V2)

 

Does that mean that instead of 33 Nm with 149 rpm you get 33 Nm / 1,414 = 23 Nm with 149 rpm?

Is the conclusion that with IONI small mige is best option and with Argon there is no reason not to take big mige other than price?

 

Spinilli

Great ! You'll love it I'm sure which ever option you order, get your order in there's a bit of a wait you know

Don't loose sleep about specs -if they were to all half in performace for sim racing these beasts will still blow everything else away

I've been running my bodnar with vibration unit right next to it (mounted on my rig), nice addition
Thinking of cadding a housing for the servo which includes a bracket for a butkicker
( not so critical for rf2 , but iracing ffb does not have any engine frequency vibration through the ffb )

 

Ah-ha. So that's the reason why the argon option exists? Max torque with IONI for the small mige will be a max torque of 23Nm, where as the Argon with a peak of 20A (or rather 14A rms) can produce 31Nm?

For the IONI then, using a 48V 10A rms powersupply = 480W, at 23Nm that's up to 458 RPM. Sound right?

edit: I'm confused by the Argon description page here: http://granitedevices.com/digital-servo-drive-argon

You see a graphic showing "20A peak output" to the motor and assuming it's peak of sine then it's 14A when calculating the peak torque output with 2.2 Nm/A = 31Nm. But then further down it says 11A continuous and 16A 1 second peak, both peak of sine suggesting the continuous and peak torques are actually 17Nm and 25Nm only. Can you shed light on this please?

 

The normal Argon firmware has 16A peak of sine. The OSW special version firmware allows for 19A peak of sine.
Now regarding continuous and peak currents, you need to understand that those servo motors are built for 24/7 kind of operations. The max continuous current is just that, the current at which the Argon will survive a permanent abuse. The same with the motors, when you see a stall torque figure, that's the torque the motor will be able to keep permanently without going too hot (however "too hot" can mean north of 140+C° for those motors).

For the OSW use, we basically put the same value for continuous and peak current and thus peak and stall torque is also the same (simracing is like early retirement for those industrial parts). For the Argon with the Lenze, that's 19A peak of sine, which results in around 20Nm. With the small MiGE you can reach 29.5Nm. But it seems that the MiGE starts running hot at those levels.

 

good post Danalm

just had an email from Ollie concerning his custom board & power delivery ( refers to the large Mige I have on order )
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at the moment, nothing out there (for the kit/price range etc) is powerful enough to run the large MiGE to 30 N.m. The Argon is capped at circa 19A but the IONI Pro currently at 18A is being developed by Granite Devices to exceed that in the near future. I’m also working on integrating Granite Devices external power stage to SIM-ple which would allow for currents up to 30A.
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anyone really after high power , Ollie's new add-on power stage can be added to a system at a later stage ( to run to peaks of 30Nm )
not sure if I'll have any interest in this , but I'll no doubt order one just out of curiosity

the add-on will also come with some chimpanzee hormone supplements for the user to inject into biceps on a bi-daily basis so absolutely everything is covered, plus rotation interia is 22.2 to the power of 5 ( which includes modulation )

 

Nice. So 10.6A rms from IONI and 13.4A rms from Argon, translates to 23.3Nm and 29.5Nm for the small mige? IONI states max wattage to be 500W (is this correct?), thus 23Nm peak torque can be sustained up to 207 RPM? But wiith Argon's 1500W limit, 29.5Nm can go up to 485 RPM (but you mentioned it's soft-capped to 300 RPM anyway and for the IONI also?). So the argon is simply the one to go with if you want higher peak torque from your motor.

edit: made some corrections to the above numbers and...

Sorry, with the IONI Pro Adrian just mentioned at 18A pos (12.7A rms), that would make the IONI capable of 28Nm with the small mige (with the same ~207 RPM limit).

Ofc, at these levels of torque, higher sustainable rpm's is not only dangerous but meaninless since the overiding sense of power will come from the torque itself providing massive amounts of rotational acceleration when in the 20-30Nm range.

Interestingly, going with the motor with higher torque coefficient (e.g. the smallest mige) whilst better at producing higher peak torque for the same peak current, it does so by also trading in the maximum speed at which it can sustain a torque output.

For example, pair the Mige and Lenze with the IONI Pro. The Mige can go up to 29Nm and the Lenze only 20Nm but the lenze can go up to 286 RPM whilst the Mige only 198 RPM which is quite close/similar to the AF Pro's 176 RPM limit. The issue boils down to the limit of voltage supply to the motor with the IONI that is limited to ~50V. Pair either motors with an Argon however and the sustainable speed can easily surpass 300 RPM.

All that being said, even with the similar speed limit, the Mige with IONI Pro is still capable of more than double the torque output of the AF Pro and since the overall power of the motor is a combination of torque x speed, the detail in ffb will still be at least twice as good as the AF Pro ofc.

For comparison, the bodnar's 480W psu and 1.6 Nm/A torque coefficient allows for a sustainable torque output up to 290 RPM (pretty much the same as the 300 RPM soft-capped limit with Argon driven OSW motors). Compare that to the AF Pro's 176 RPM limit which is nearly half.

 

If the big MiGe requires more power for the same torque and rpm as the small MiGe, and the IONI is already limited, then wouldn't the small MiGe actually be capable of more power (torque and/or rpm) than the big MiGe if it's connected to the IONI since the IONI is the limiting factor rather than the motors?

 

yes. So IONI Pro (peak 18A pos = 12.7A rms) with small mige will get you a peak torque 28Nm (pretty much the same as Argon at 29.5Nm). And if IONI Pro can truly output up to 52V to motor, then peak power available is 660W. Translates to peak speed of 225 RPM. Only benefit of pairing Argon with small mige is peak speed possible is around 486 RPM but as has been mentioned by the guys above, both Argon and IONI are limited to 300 RPM in software anyway.

However, I believe the peak speed (which translates to peak power) past a certain point may matter less here though because the torque range is so much larger (going up to 30Nm).

If i were you, i'd go with IONI Pro + small mige.

 

been waiting to long for some laser cut plates of an f1 wheel I've cadded,
also not ordered moulding kit I was going to experiment making the handles for it -will be a super steering wheel when done but putting it off for the winter now

in the meantime I've gone for a quick easy cheap solution & ordered a fanatic f1 rim, ( 99 euro ! )
what I'll have to do :


scratch PCB , remove display ( cut out of PCB as its all one unit inside )
solder in new wires ( to existing buttons & shifter micro switches)
drill some holes add 3 to 4 rotary's
wire all to bodnar circuit ( I have a few of these in my expanding stock of sim gear lol )
remove fanatic logo on front
cover with carbon finish
remove fanatic QR & drill/attach monkey servo QR
no need for display as I use VR (& pretty sure VR will be common place anyhow)

makes for a cheap & simply solution for a kick ass f1 fully functioning wheel
I'll maybe sell it when my own one gets going again, those fanatic ones feel nice though

 

noticing this OSW firmware is being improved all the time,
on the hardware whilst any make/model complete industry grade servo is totally top notch
there are perhaps ( for sim racing ) some only just noticeable differences in "feel" between different systems & servo motors

so I'm very interested in doing some comparisons etc

I'm very tuned into my bodnar, I'll have a OSW built/running soon using large midge ( & interchangeable to small Mige's) I'll run this for about a month on my rig

next year I may be on the look out for kollmorgon 54g servo to build based on OSW
(hoping to get one through trade for best cost as these are expensive)

new OSW firmware coming soon, as this is open source and being driven my sim racing enthusiasts even the crunched down custom circuits ( as in Ollie's kit ) offer pretty much all the adjustability that would be required for sim racing ( & more )
so I'm trying to keep up to date with software updates / features etc

 

Can you explain what that means? What's different in this kit compared to what most people get in their OSW kits?

 

his custom circuit " SIM-ple for IONI" (he calls it) is a custom motherboard with consolidation features, minimises wiring & simplifes the build ( & makes it more economical as features that will never be needed for sim racing are left out )

I think this also avoids the need for the disco board ( as the only chips that are needed are on the main custom board)
all adjustablilty (possible for sim racing) are maintained though I understand

bear in mind servo systems (in this sense) are equipped to do many many industrial operations , weight detection , jogging with detection etc all this is not needed for sim racing, I assume all these other features have been excluded

the custom bodnar board was crunched down even more thus alot of the adjustability in the OSW (which is a lot & perhaps a lot more than we need ) are not possible in the bodnar system unless a new board is fitted
( which is what Leo is about to release, maybe due to the OSW adjustablilty ) , this is my interpretation of recent events anyhow