Sim Racing servo ffb systems : OSW & Bodnar

your posts are way way to long & I'd switch off about 1/3 in or even send me to sleep ,
anyhow good luck if you ever design/build your own ffb system
( no offence etc, I know your a good guy )

 

Been trying to keep up with the posts here but keep getting lost!
Anyhow off tomorrow to Leo's to collect my new Simsteering setup, first few batches of the new system are now available and really looking forward to it.
In the last few weeks I've spent a lot of time researching all the options, OSW/AF/Bodnar and for myself as an engineer ( although only boring renewable energy technology!) it came down to the quality of components, design and British engineering that convinced me to splash out on this system.
I expect I will be asking a lot of questions in the next few days re FFB setup in RF2 etc so thanks in advance!

 

You're always full of interesting info DrR1pper, though between your incessant editing and verbosity and Adrian's inability to read for 4 mins while still (apparently) disagreeing with a lot of what he hasn't read it can be a difficult conversation to stay interested in.

All this stuff about inertia though, and how quickly a wheel can reach x rpm, seems somewhat unrelated to the application of simracing where someone's actually holding the wheel.

I would have thought nearly all the torque you feel will be at low rpm or even at rest. The times you're holding the wheel lightly will also be the times lower simulated forces are produced (on straights, for example), while the much heavier forces generated during cornering will be generally accompanied by a couple of taut and slightly sweaty arms trying to put the wheel in the intended position, especially with motors like these. Those strained shoulders and forearms are going to add a lot of inertia to the system, making wheel-only response times meaningless.

In practical terms, are you likely to encounter 200 rpm while holding onto the wheel in a driving situation? I don't know (and I mean that literally), but if the answer were "no" it would completely invalidate your assertion regarding a 200 vs 300 rpm motor. And that's not attacking anything you've said or looking for an argument; I just think the demands of the application need to be assessed before assuming bigger (and faster) is better.

 

lol, I've successfully forgotten more than I know about tech specs etc of servo systems etc, I used to be lectured on it for hours on end a few years ago, I avoid getting involved now, plus mostly irrelevant for sim racing anyhow

I understand if it all seems new & exciting though to some as this tech is filtering into our hobbies ( which is a great thing ) & some like to take as much subject matter as poss
( all the irrelevant stuff) around in circles , nothing really can be done with this information for someone choosing a ffb system ( except basic stuff like Nm options )
build quilty of a unit -price will usually be a measure of this -very simple
.....hands on trying them out is the key ( or carefully listing to some ones fairly trusted who has tried + some one like Barry's review & forth coming ones etc )

if you were to check back on a lot of the posts though some of it is nonsense a lot not applicable ( to sim racing) & some keeps getting repeated mostly by people who have never even tested or calibrated hands on these types of systems ( or in fact have ever owned one )

that's why it totally bores the socks of me & I don't really read

no harm done though I guess & very easy for me just to skim passed etc


p.s anyone local to me can nip in when I'm setup with OSW ( small & lg midge ) + bodnar
do a blind test then I'm sure you'll want to forget about 400 pointless statistics jumbling around in your head ( if yr at that stage yet? )

ps lazza I disagree with what I've not read as I'm pretty sure I'd disagree if I'd had read anyhow -but disagreeing without reading is simply faster lol

I'm quite interested in people's actual reason for buying & which ( or not bothering to buy )
pics of maybe OSW builds and settings , marks7 1st impressions of his bodnar when he gets up and running this weekend, anyone discovering new configurations for the OSW maybe,
any perceive differences ( & how subtle ) of differences between different systems
.....actual hands on factual stuff like this,
to much interia? ..then go and drill some bloody holes in your steering wheel or cut your finger nails to reduce rotational weight

 

A few pages back someone commented that someone from the SimX community had been given a 36V psu to test with their AFPro and supposedly found it made it more powerful/responsive but still not enough to match the bodnar/OSW. Understandable, since the bodnar/OSW still have at least 33% higher peak voltage (thus peak speed also) and higher peak torque (e.g. +23% for bodnar).

At the very least, it confirms there is still a performance difference to be gained with increasing the peak voltage potential (and thus peak speed potential) for the AF Pro.

But you can also look at this from the other side and ask, if peak speed which is related to peak voltage doesn't matter, then why does the bodnar/osw motors come with at least 48V psu's? Why not 36V or even 24V?

Also, there are two videos on the previous page that judging by eye alone (so large possibility of error ofc) i think demonstrate how quickly the steering wheel mass can suddenly accelerate up to peak speed of the motor before you know it or can do anything about. I mean, human reaction time is what, 200ms average in the best of us in the most convenient test scenario, whilst acceleration time to peak speed (for the AF Pro for example with only 13Nm peak output) i measured to be less than 100ms. I also remember being unable to stabalise the steering wheel properly from the constant snapping violently left or right motion from the ffb when driving when i last tried Adrians bodnar for a few hours, which wasn't even at full torque. All you could do was generally go along with it whilst trying to steer it's average position in the direction you desire, which is what i see from the videos in the previous page. And the few times i crashed, the wheel would snap out of my hands, one time cutting my hand up as there were bare spiky soldering points on the steering wheel electronics.

But i understand where you're coming from Lazza. If we could grip the wheel in such a way that ensured maximum resistance in either direction, so the wheel could not accelerate as fast, then surely the peak speed would not be attainable for the electric motor in a short enough time period before some reverse direction ffb signal works on canceling out the impact it has had on steering wheel mass's momentum.

However, being the imperfect creatures that were are, I think there are (many) times/instances where the peak speed can easily be reached in way less than 0.1s. For example, when the ffb torque output from the motor suddenly aligns with the direction that you were applying torque to the steering wheel that only just before was opposing the momentum direction of the ffb wheel. The combination can significantly rise the net effective torque acting on the steering wheel mass that will in turn accelerate it up to peak speed far quicker than even the hands-free scenario of just the motor doing the work on the steering mass.

do you see where i'm coming from? This is also why i said increasing the peak voltage X% amount can give up to X% more torque perceived.

 

Will that power add-on thing from Ollie help to increase torque or rpm?

Also, in your personal opinion, do you think the small MiGe + IONI Pro without the power add-on will be capable of enough rpm (or x torque @ x rpm or whatever) to avoid the issues that apparently plague the Accuforce (relatively speaking of course)?

 

I noticed this too, and even occasionally get it with my current wheel although I can stop it because they wheel isn't powerful enough to overcome me. This is just wrong. However, if the motor is NOT the weak link in the chain, then wouldn't this problem be attributed to the game/sim or even possibly the "middleman" software between the game and physical motor rather than the actual motor? Or maybe it's a problem that cannot be properly rectified until the entire FFB philosophy of video games changes (I think Leo Bodnar was the one who wrote about this)?

 

Well...this kind of motor is used in machine tools, industrial robots etc...I`m not sure, but maybe these kind of stuff is a little bit an overkill for simracing applications?

 

If you're talking about the "sim-pie" thing, if it increases the peak current output to motor then it will increase the peak torque output possible from the motor. If it provides a higher peak voltage output then it will allow the motor to run up to a higher peak speed. Simply put, for a specific motor, pairing it with a PSU/Drive combo that can supply it with more voltage will result in more speed and proportionately so. So generally speaking, double peak voltage = double peak speed.

So if this "Sim-Pie" will allow the IONI Pro to go above 55V (pos), then yes, it will increase peak speed/rpm. If it can also make increase the IONI Pro's peak current above 18A (pos), it will also increase the peak torque possible with the motor.

If the Sim-Pie can and does do the above, then it will make the FFB feel stronger and more responsive. But whether it's needed or not, especially for the small mige, i can only tell you that i think it's enough. Enough peak speed and peak torque, that it'll rattle your brains out. I mean, IONI Pro + small mige is capable of more than what the bodnar wheel is able to output already and in my experience that was already plenty powerful. Your appetite for level of strength, violence and responsiveness of ffb however may be larger than mine.

At the very least, i think IONI Pro + small mige is a good starting place. Ofc though, going with another psu+drive combo with more peak voltage will naturally make even the small mige more powerful. Perhaps sim-pie can do that or not. You'll have to research it.

Being able to stop it is due to as you say, the motor not having enough peak power output = peak torque output x peak speed/rpm. But as you're surmising towards the end there, yes, it's all wrong/bad anyway but that's another story and one we've discussed at length already in the past.

 

In some ways, but it seems like in some cases where you have decently high sustained forces (long chains of corners, but certain cars on certain ovals too) you'd either need something bigger or more than just air (my assumption) cooling it if you wanted to replicate true forces.

Anyway, with inertia earlier there were questions about the inertia of the different motors, and that was pretty quickly dismissed because the wheel itself adds a lot more. Now if I'm using a 20+Nm wheel, have been using it for a while, and I'm heading into a high speed corner where I know I'm going to encounter some high forces... I'm not holding that thing with my fingertips. So without knowing figures it seems system inertia is going to skyrocket and 0.1s to full RPM seems unlikely.

And, that 0.1s is full force. 100% output. I can't see why you'd suddenly encounter that sort of force from 0 (let alone a value in the other polarity) except in certain situations where just like real life you'd take your hands off the wheel. Chances are a spike to full force will just be an addition to the quite strong force I'm already feeling, so it'll give a jolt but it won't start spinning to full speed because I'm already pushing against it. Will I then get a sudden force in the opposite direction? Maybe to 0, maybe slightly opposite, but nothing near full force. So for the driving I personally do, I can't see any torque dropoff above a decent figure (150rpm? 200rpm?) being an issue.

However, something I forgot that Paul mentioned (much) earlier was drifting, where you do want the wheel spinning quickly all by itself. So let's say you decide 300rpm isn't quite quick enough (I suspect it might be close, but haven't measured/timed videos) so you want 600rpm. Assuming the wheel limit can be set that high, is there any reason these motors can't push the (unloaded) wheel that fast? If there's hardly any torque at that speed it doesn't matter - you're not holding it - and when you grab it it's back to square 1 and ready to output full power. Right? (and in drift videos I see guys catching the spinning wheel with half a hand sometimes... I don't think there's a whole lot of torque involved)

Finally, skimming over the video in the OP again all those wheels look lifeless. It's almost like just a centering spring unless they start to lose the back end, then it kicks the other way. Is that an iRacing thing? (sorry to get sim vs sim - just curious why these high powered wheels tend to look more tame than my g27...) To be honest it's a bit hard to judge because half the drivers have the "oh no, I'm understeering - turn moooar!" mentality.

 

The kind of motor used is not the determining factor of how the ffb will feel. What determines the ffb performance of a motor is how it's driven (i.e. its PSU+Driver combination driving the motor). Because the higher the peak voltage and peak current the PSU+Driver can deliver the motor, the higher the peak speed and peak torque of the motor will be. And it's the combination of peak motor torque and peak motor speed/rpm that determines how you will "feel" it will perform, i.e how powerful the ffb will "feel".

Imagine you had the bodnar sim steering system but swapped out the 48V-10A (=480W peak power) PSU driving it for a 12V-10A (=120W peak power = 75% less) PSU. The motor is still the exact same "industrial grade servo motor", it can still output up to 16Nm (due to the same 10A peak output) but when you come to experience the ffb it can deliver with this less powerful psu, the ffb experience would most certainly not be the same. In fact, the power you would "feel" from the ffb wheel would be 4x weaker and the peak torques you "feel" as if coming from the motor will "feel" 4x weaker, so much less that the AF-Pro, even with it's lower 13Nm peak torque output would undoubtedly "feel" more alive and higher in torque output than it.

It's the same reason why if you compared the T500RS to say the CSWv1/CSR-Elite ffb wheels, even if you reduced the (effective) motor peak torque output from the motor of the t500 to match the CSW/CSR-e, the T500 feels more powerful. Why? Because the motor (+gearing ratio it uses) allows it to go up to a higher peak speed. So if you were to compare the static torque output (i.e. by holding the wheel in a stationary/static position and measuring the pure torque output from the motor) it would be the same as for the CSWv1/CSR-E. But when the steering wheel of the T500RS is at peak speed/momentum and you try to stop it just as quickly as trying to stop a CSWv1/CSR-e wheel when it's at peak speed/momentum, you will need to use a lot more torque with the T500RS to do bring it to rest as quickly. This is due to simple momentum theory.

Case in point, when i made the upgrade from CSR-Elite to T500RS, i honestly thought the T500's peak torque output form it's motor was 100-200% higher (i.e. 2-3x higher) than my CSR-E. But as i've since been told, the T500RS's peak effective torque output from its motor is actually only 20-25% higher (i.e. 1.2-1.3x more). The reason for the perceived higher motor torque output was in fact due to the T500 having a higher peak speed/momentum.


[HR][/HR]
side-note: I say "(effective) motor peak torque output" when comparing the the T500RS to CSWv1/CSR-E because even if their static torque outputs were the same, due to different gearing/transmission ratios the torque output from the motors will not be the same. Point is, it's the effective torque output on the steering shaft/mass that matters here and not the true amount of torque output from the motor. But when comparing DD wheels, we don't need to make this distinction because they already have the same gearing ratio (of 1:1) so their effect and true motor torque outputs are the same, hence we just say motor torque output.

 

Agreed. That aspect of speed and power only affect the "feel" of the ffb when the wheel manages to sort of run away with itself. But i think you'd be surprised how quickly and often that happens in practice when you get up to these high torque motors with as you rightly say such low overall system inertia. And the higher the peak torque, the faster it can reach peak speed. So for the AF-Pro outputting its peak torque of 13Nm, it takes only 0.1s but then for a 28Nm peak motor with the same steering wheel shaft inertia as the AF-Pro's, it would take less than 0.05s due to having double the acceleration rate.

hmm...you make a good argument here and i don't doubt you that there is going to be a limit of peak speed at which any higher for sim racing use would produce no detectible difference in the ffb experience because there isn't enough time for the steering mass to reach a higher speed in practice. But i can't shake the feeling it's not less than 150rpm or 200rpm because 150rpm is what the AF Pro already has and as mentioned earlier, someone has tried a 50% higher voltage AF Pro and found it felt more powerful/stronger. Using that higher peak voltage psu would not increase the peak torque, so we know it can't be due to change in torque. But we know to increase it's peak voltage supply is to increase a motors peak speed possible.

When i measured/timed it, it took less than 90 degrees rotation (though could have been less) for the AF Pro steering wheel mass to accelerate up to its peak speed of 150RPM in less than 0.1s. As you rightly said, this was at full torque as well so if when drifting the ffb output is less than peak torque (which i think may or may not be optimal...never tested myself), average speed will be less too ofc.

 

disagree !


only joking , out of interest what ffb wheel do you use lazza ?

 

Why does it matter if you use an Argon, IONI Pro, or non-Pro IONI if all you gotta do is "throw" a more powerful PSU in the mix?

I'm clearly not understanding the difference between A. the Argon/IONI-P/IONI, B. SIM-ple, and C. a PSU and how they're related and affect eachother.

 

Some guy on some forum said that:"Servo motors maintain their rated torque to about 90% of their no load RPM. Stepper motors lose up to 80% of their maximum torque at 90% of their maximum RPM." Can this have effect to AF's feel?

 

I wonder if there is a cost effective surgical procedure available to reduce some mass ( bone&flesh) from our hands ?
this would help to further reduce rotational inertia, especially applicable for sim racers with large hands

could be the next big thing in sim racing ?

 

yes , sorry I mean no

I'll change that to I concur

good post by the way

 

What he's said is generally correct. But is it relevant here? I don't think so. It is true that stepper motor torque output falls dramatically and much earlier on in it's speed range than non-stepper motors but this usually occurs when speed exceeds at least ~5 RPS = 300 RPM. So the stepper motor of the AF Pro should not suffer a torque drop off because i've measured its peak speed to be 150RPM.

Steppers characteristically suffer from a lower speed point where torque output begins to fall drastically because of they're design. Steppers are designed to be used in their stepper fashion first and foremost and they they achieve the ability to perform open loop position control is to have many many stator poles. Way way more than non-stepper motors. The disadvantage of this is vs a motor with way less stator poles is that in order to achieve the same rotation speed, each pole must alternate many more times per rotation than in non-stepper motors. Couple the fact that cramming so many more poles in means less space per pole to many as many windings, etc, and wire must be thinner, etc, means the stepper motor has a lower peak speed that it can maintain/sustain its rate torque output at.

But again, this usually only takes effect when the rotation speed is at least ~5 RPS = 300 RPM if not higher. And the higher the peak voltage supply to the motor, the higher the speed point before this effect kicks in (i.e. the higher the peak speed can/will be....just like for non-stepper motors...why/how? Because all motors in principle are driven exactly the same way).

As an arbitrary stepper torque-speed curve example, see here:

 

So to drive a motor you need a driver/controler and a PSU. The choice in PSU dictates the amount of peak voltage and thus peak current that the driver/controller can draw from. The driver/controller is what actually controls the amount of current supplied to the motor at any moment in time. However the driver/controller for design reasons will have limits on how much current it can draw from the PSU and/or feed to the motor without itself burning out, so there exists a voltage/current limitation there as well.

I believe the IONI driver/controller is rated for up to 55V 15A pos = 412W rms, IONI Pro at up to 55V 18A pos = 500W rms and Argon (which i believe is both a driver/controller and a PSU under its hood if i'm not mistaken) up to 19A pos (though i think some have gone up to even 26A pos) and i'm not sure about the voltage but have read its description page stating it can power up to 1500 Watts.

 

Oh I got it now, thanks again. So the SIM-ple effectively raises what the IONI/IONI-P can handle from the PSU or does it raise what the PSU itself can output?