Sim Racing servo ffb systems : OSW & Bodnar

Thanks, fixed that.

I saw it in an OSW wiki page that holding torque was written for the rated torque values instead of rated torque. So I thought they were the same but you're probably correct. I'll change the chart to "rated" instead of "holding".

EDIT: I don't know if this is official from MiGe themselves but it's listed as "holding" here, not "rated". LINK TO MiGe PDF. I guess I'll hold out on changing it in my chart for now.

Ya, that sounds odd. Does the fact that all three ("small" and both "mediums") are essentially the same motor, but with more amps/power pumped into the "mediums", mean that the rpm and peak torque increases but the rated torque doesn't? Or should all the torque parameters/specs increase when given more amps/power?

EDIT: In the PDF link provided above, they both are shown as 10 Nm...Hmmm...

Ok that adds to the confusion. How is the guy from the iRacing forums selling the "big" MiGe with the IONI drive if the IONI is so weak?

If the Argon maxes out when reaching the "medium-small" MiGe's official rated specs, then what about people using the "big" MiGe and/or overamped small MiGes?? I thought the Argon was the one with more than enough power to drive all these to their full potential and it was only the IONI that wasn't?

EDIT: I just came across the following with regards to someone asking if it's worth getting the "big" MiGe over the "small" one

source --> https://marcushwang.wordpress.com/2015/01/18/my-mmos-sim-wheel-project/

Ok, now I'm even more confused. It says - like you said - the Argon can't support enough power in order for there to be a difference between the "big" and "small" MiGe. WTF? So people have been wasting their money all this time getting the "big" MiGe? What about all the youtube videos claiming upwards of 30 Nm? Then it get's even more confusing as he says that this will change with the IONI? I thought the IONI could handle even less max power than the Argon? This is getting VERY frustrating due to all sorts of inconsistencies everywhere regarding information.

If that's the case then would one of the "medium" MiGes be the best out of all models? It has 25 Nm of torque which should easily reach the "big" MiGe's 30 Nm with a bit of overamping (people even safely overamp the "small" MiGe's 20 Nm to 27 Nm) yet it has the lower rotor inertia which can possibly provide better FFB "quality"/clarity/detail and response times...So would either of the largely ignored "medium" MiGe models actually in-fact be the best MiGe motor for simracing?



Last question. Let's say there are two motors. They both have a peak torque of 30 Nm but one's rpm is 1500, the other's is 2500. Is the motor with 1500 rpm superior since it can output the same amount of torque but doesn't need all those rpms to do so? An example of this would be both "medium" MiGes where both specs look absolutely identical other than rpm...

 

http://www.indiadiesel.com/images/TORQUE_SPEED_CHARACTERISTICS.jpg

peak torgue goes down as speed increases.

Power limit of servo controller (IONI/Argon) comes into play in high engine speeds. With ioni it starts to limit torgue earlier than with argon, And with AF's 240W it happens much earlier.

 

Nice find, looks legit from the MiGe manufactures but i see even further confusion. If you look at page one, they explain how their motor naming system works. The first 3 numbers after the M represents the "rated torque". So for 130ST-M10015, the 100 represents a rated torque of 10.0Nm. But if you check every motor in the pdf, you'll find that the 3 digits in the motor name matches with what they call the "holding torque" of the motor....except for on page 18 where the torque still matches up but is not called the holding torque but the instead the rated torque. It's a mess. The Alibaba page i showed earlier ilists it as the rated torque and usually stuff like this when sold on alibaba is sold by the manufacture directly. So not really sure what to believe it is now, lol. Some motors do have the same value for holding and rated i guess.

But there has to be something different about the stator coil windings or else the line-to-line resistance and inductance values should be the same. What could be happening is that the higher rated current motors are using slightly different coil winding material which would explain the difference in resistance and inductance spec. For instance, the resistance and inductance of the stator windings need to be lower in order for higher safely sustainable rotation speeds to be possible and we can see this is the case between each motor (by their "rated speed"). At the same time, lowering the resistance also means the motor will produce less heat for the same amount of current. Thus the safe amount of current that the motor can safely take (i.e. rated current) up to its rated speed (i.e. 0 RPM to rated RPM) can be higher. Hence we see an increase in the peak torque and/or rated speed of the motors.

Now, that all being said, rated stats tell us what the manufactures has found the motor can safely operate at continuously without damage or rather premature failure. But there is still an intermittent region of performance they can operate in. One stat all manufactures provide for this is the Peak torque which is the maximum stall torque the manufactures deem safe to operate the motor at for short periods/bursts of time. So it's not as if you can't make the smallest mige output torques like the biggest mige, because you can but the question becomes for how long and what is the risk of permanent damage. The speed limit for the motor however is a bit more determined by limiting factors such as stator coil winding resistance and inductance.

Well, it will work but you will just loose top speed. So for example, all the Mige's are rated at 220V. Now if we take the big mige (130ST*-M15015) and pair it up with the IONI and provide it 9.5A, we can still get to output its rated/holding torque (whichever of the two it actually is) of 10Nm. But the IONI can only output up to 52V and not the full 220V that the MIGEs are rated at which means the motor will not be able to deliver the 10Nm all the way up to 1500 RPM (in the case of the 130ST*-M15015). It will probably be around (52/220* 1500=) 350 RPM that it can maintain and output of 10Nm instead which equates to 5.8 rev/s (only double that of the AF Pro). Using an Argon on the other hand will allow the motor to run 10Nm all the way up to 1500 RPM = 25 rev/s. Perhaps 5.8 rev/s is enough to avoid the AF Pro issue or maybe it's not. Safest bet would be the argon ofc but it's a bit of a leap in price ofc.

Ah, yes, sorry. You'll most likely never find yourself reaching the rated speed of any of the motors with your hands still attached to the wheel, so i guess the argon is still perfectly fine to use with the big mige.

Like i said above, you can and will get the 30Nm, it just can't be sustained to the rated speed of the motor due to a lack of voltage to drive the current at higher RPM's. But with the rotation speeds you can expect to see in-game, it's likely not to be an issue.

So if price is no issue, i would get either the 130ST*-M10015*or 130ST*-M15015 with an argon. The bigger brothers of these two are just higher speed potential...so high i doubt you'll encounter or want to encounter them.

When you put it like that, yes, i think the medium is best overall.

I think you know the answer to this now.

 

About the rotor/motor inertia: inertia difference of small and big mige = (8,3 kg*cm^2,) equals 37 grams on the rim of 30 cm diameter steering wheel.

 

+1

 

about 20 to 30 of us chipped in some dosh to have an OSW built ( another Iracing memeber is putting it together ) to send into Iracing
HQ, I hope Iracing will improve its ffb
( Iracing ffb is pretty good already & it's only my opinion that rf2's is better other opinions may differ etc)

 

just dot reading through some of these long posts,

remember for sim racing the motor dose not have to rotate that much or spin,
they are moving in small amounts in one direction
against constant resistance & being held relatively still

the speed these servo systems ( I state system because it's important that it's a full servo system -the actual motor is only a part of it ) are incredibly good at applying forces , dropping it off quickly changing direction many times per second , applying a constant force and still being able to deliver subtle detail above, low latency immediate response with no fallout, heatfade
very low chance of clip ( Clipping is a problem for users of low to mid range wheel & that includes the AF, never really hear bodnar or OSW users mention clipping etc )



think of it in terms of hifi, a great setup will consist of a good quality amplifier with good quality speakers, good media

media =ffb from sim
amp = controller circuits (& decent psu)
speakers = motor

a good hifi setup will play music & should deliver good clarity across all volumes, not "rumble" or loose clarity when a lot of multiple sounds are present ( lots of bass/acoustic together etc) -the quality will still be pleasing to the ear , no distortion at higher levels
( "clipping" ) , perform very well on bass as well as acoustics


don't get hung up on rpm, Nm, volts & how hot the sausages are ,
going full servo system is ultra high end
like receiving £3000 worth of award winning Yamaha Amp with a decently matched set of B&W speakers ...lovely


p.s a bit off topic but I just hate cheap nasty sound systems , they are everywhere, they are like a pain in my ears lol
it's the same with bad ffb

 

Dr.R thank you so, so , so much for picking apart all my questions 1 by 1. Many others may have just written 1 vague response (if even replying at all, lol) rather than addressing all my questions and concerns individually. Man, thank you so, so much.


I'm starting to really get a grasp of things...and a much clearer idea of what to buy...

Ok, so the IONI and Argon can both provide the full 25 or 30 Nm of torque but it's just that the more powerful one (argon) can reach a higher rpm before not being able to apply that torque amount anymore...However, the rpm that this happens at with the Argon is probably so high that it's irrelevant for us simracers. Ya?

There is no point in getting the "medium-big" MiGe because it is identical to the "medium-small" other than 2500 rpm VS 1500 rpm which is practically pointless for simracing and you'd probably never want that speed anyways as it's probably unrealistic and no sim would/should ever be outputting that speed anyways (except maybe a crash or something). Ya?

If 30 Nm was the max I ever wanted. Then at first I thought I'd rather choose the "medium-small" over the "big" and just overamp it by 5 Nm to the "big's" 30 Nm. However, the "big" also has 15 Nm of holding (or rated) torque VS the medium's 10. How much difference does that make? Does it even make a difference because, once overamped from 25 Nm to 30 Nm, will that overamping also increase the holding/rated torque to around 15 Nm? Or will that still be at 10 Nm despite being overamped?


I'v pretty much narrowed this down to the "medium-small" and the "big". Pretty much down to those two.

37......GRAMS???!!! Is that how much the 40-ish % increase from the small/medium to the large essentially is?? That sounds insanely minute, I mean so minute that it seems absolutely irrelevant to simracing even to the most hardcore of the hardcore.

 

According to my calculation, yes. It was surprising for me too.

Here is equation i used if someone wants to check it for mistakes: mr^2 = J -> m = J / (r^2)
.........................................................................................................-> m = 8,3 kg*cm^2 / ((15 cm)^2) = 0,0368 kg

m = mass
r = radius
J = moment of inertia

Yes 37 g is probably irrelevant escpecially with the forces we speak about.

 

No worries.

You got it.

2 for 2.

Sorry, you make a very good point. For the additional 5Nm higher sustainable rated/holding torque and peak torque, the big is better. It will give you more head-room to overamp in effect.

 

I doubt 37 grams would even make a difference with an AF, or heck even a CSW v2 or T500RS. I mean, 37 grams is probably like the weight of one button on the wheel, lol. It's astonishing that those specs are so much looked at considering the performance of the machine and how unbelievably minute 37 grams, or even 100 or 200 is compared to the outright performance of the wheel. It would be like 1 car having 535.00000 HP and another car having 535.01154 HP. Basically pointless.

But will the "medium", overamped by 5 Nm (to match the "big's" 30 Nm), also have it's rated/holding torque raised when overamped (to approx. 15 Nm to match the "big's")? Or does the rated/holding torque stay the same (10 Nm) - even though overamped - and therefore only the peak torque rises?

 

Yeah and that sounds right and all but then i remember hearing people saying they can notice a slight difference in ffb responsiveness between different rotor inertia's (e.g. lenze vs mige which is around 4x smaller) but for all we know it could be placebo, etc. But there has to be an advantageous reason for less rotor inertia even if only outside sim racing use because it really seems to be the main if not only spec-wise differentiator between the $200 and $1000 motors. Or perhaps it's only important for industrial application uses. I'm still a little hesitant to brush aside all possibility of its relevancy to sim racing use though despite the good and sound logical argument korva has put forth.

Good question and it should stay the same. The reason is that the rated/holding torque which is what the manufactures deems to be the safely maintainable amount of continuous torque output is really determined by the motor size in combination with aspects such as how thin the coil wiring is as the thinner it is the greater number of winding loops you can get in the same space which is great as it then increases the magnetic field strength of the stator for less current but thinner wires also increases the wires resistance which means it warms up more so you have to lower the current, etc, so either way you end up with the same sort of net limitation. But there are also other trade-offs if you go with bigger wires, etc, so it's all a compromise. As you can see on the pdf you provided too, the M150XX's are ~13% longer, 25% heavier and the rotor inertia is 43% larger too, suggesting there is more permanent magnet mass on the rotor as well as larger stator surface area, etc, all culminating is a larger magnetic field strength = more torque for the same amount of current.

Overamping can seem a little misleading too because the motor will only draw as much current as it needs at any one moment in time. So what overamping really means is how high you set the upper limit of available current that the motor can draw (or rather that your controller can deliver to the motor). And as with any motor, overamping above the manufactures rated recommendation causes the motor to operate outside of its continuous region and into it's intermittent region or even higher depending on how much you've "overamped". To know whether an overamp is safe or not requires physically testing the motor and from the sounds of things, people seem to have managed to get the small mige to safely use overamps values/targets that allow them to achieve periodic 100% ffb outputs of 27Nm whilst in sim without their motor failing. So who knows how much higher you might be able to get with the medium or big mige motors (that is if it's even desirable to do so).

 

There is also difference in encoder resolution. Lenze 16384 and Mige 10000.

 

True, but surely that can't be the reason for the cost difference.

edit: woops, forgot the big weight difference differentiator that is actually pretty considerable when comparing the 30Nm peak lenze vs mige, 9.5kg vs 14.4kg. If the motor were part of an industrial robotic arm assembly, i can see how the lighter it is the considerably better for speed and control of it all and hence the significant price premium. For an ffb wheel...can't see it being so relevant.

But then that leaves me pondering why the hell OSW has the lenze on it's list of motors to choose from in the first place.

 

Also Lenze problably is not made in china.

 

lol, good point but there surely must be more to it than that...right?

Again, or else why even put it on the OSW list of motors to recommend people choose from? Either the OSW creator doesn't realise there is no difference or there is a noticeable difference hence why it's on the list of options to choose from or some people just don't like buying s*** made in china and the creator is simply helping provide alternative options for those peeps who prefer (possibly) western manufactured alternatives even if it means getting ripped off?

 

Difference between lenze and big mige was equal to 91 grams on steering wheel.
I don't know could that be felt in some way, but definetly not worth the price difference alone. Not for me atleast.

 

Spinelli

are you ordering an OSW too? ( sorry I've not read the long posts ) if so which Mige ?

you know I've ordered the 30Nm ( large Mige ) ,
I'm also thinking of adding the small Mige motor too so I can test/compare etc

 

re. country of manufacturing , there are a lot of branded companies re-labelling these Chinese imports (& charging a much higher price)

my pals in engineering & will not touch them for their robotics ( their budgets are very high & go very expensive to cover themselves etc )
saying that they've never tried or tested them

I've not heard of anyone yet having trouble ( sim racing )

p.s there are some enthusiasts that seem to be trying to get their hands on every suitable servo motor going to try out on their OSW setup - all seemingly with a different view of what's best
( although I guess ...best for them )

 

Seems to me you guys are overanalizing the problems.
There are dozens of people who already have realised the OSW in the way descripted by Beano.
As Adrianstealth et al. mentioned, simwheel application is really easypeasy for this kind of motors, you really need just one number: the torque constant.
Rated constat torque and rated current is meaningless because you'll never ever run the motors at 1500 rpm 10 Nm continously for years.
So, if you are budget tight like me, small MiGE IS your motor of choice because:
1. torque constant is 2.2 Nm/A, this means that with IONI and a 48V 12.5A power supply you can safely run the motor with ffb torque peaks higher than 25 Nm (and even more). Others medium MIGE have smaller torque constant so, to reach the same peak torque you need a bigger power supply or the ARGON.
2. Smaller MIGE is easier to configure in Granity software ( basically input some data copied from the tutos and you're ready to go). Others are never been used so you need to find THOSE numbers by yourself: not that the procedure is overcomplicated, but, especially if you're not an expert, **** happens.
3. If you want absolutely the Bigger MIGE to reach 30 Nm peak, iONI alone is not enough because of the smaller torque constant.
4. If you want the Lenze for I don't know why, and you want to reach 30 Nm peak IONI alone is not enough because of the smaller torque constant.

Also rated rpm at rated voltage is a nearly useless number because no OSW need to use full rpm, even ARGON applications are software limited at 300 rpm max and this doesn't limit the accelearation.

Read the Beano tutorial in the other thread, order all the materials and start soldering.
I already have all the materials excluding the steering wheel, and I have spent at the moment less than 800 €.