Which is the best Direct Drive motor? Simucube developers will find out

Simucube 1 News
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I understand the reason why some DD wheel suppliers choose to show torque-charts are shown, they serve a dual-purpose, from my humble point of view.

Be assured though, those tests are not required for DD wheels based on Simucube1/IONI or Simucube2 controllers and related servos design, more so for SC2 with it’s silent, smooth and efficient passive-cooled design concept.

As I have stated quite a while back when these first appeared, Stall-torque is meaningless really in a sim-environment, peak-torque is really what matters, as we never enter extended stall-conditions in racing-sims, where one might exceed the mechanical time-constant of the servos, forcing torque-deration. At least not with in-runner servos with their much higher thermal-mass.

Out-runner servos is a different proposition, the higher torque capacity/weight/size comes with the disadvantage of a significantly reduced area for the stator, which causes big challenges for ripple-control algorithms, as well as the challenge getting the heat out of a servo, very often requiring active cooling. Fan-noise will be dependant on the quality and size of the fan.

So whilst out-runner style-servos are great for lightweight torquey equipment, higher-end precision position-based CNC Automation equipment are all using in-runner style servos due to their superior smoothness wrt significantly reduced ripple-torque due to a large stator-area (by design) and thermal management properties, reduced ripple allows for much greater positional accuracy, vs the out-runner style servos.

Guys, there are very good reasons an industrial drive-controller supplier like Granite Devices went with in-runner servos over other types: quality, reliability, absolute the best in positional accuracy, smoothness and other factors, are only a few key differentiators.

SC2 is in-runner and passive cooled, by far the best current DD wheel on the market, from my initial testing. More later after longer seat-time.

Cheers,
Beano

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To me it seems as thermal throttling to stay within safe operating temperature, but without known fan characteristics (fan speed) and overall sound characteristics if those aspects are interesting things to the user. The product seems to have fan control algorithm that has “steps” as the stall torque also decreases in “steps”. In anycase, this picture is needed/useful for the mfg engineering work, not so much to the end-user provided that the product’s torque output does not (in normal conditions) behave as a function of the temperature of the parts inside the product -> thermal throttling in normal conditions. According to Brion the wheelbase should have linear torque output with the exception of the end to end travel bumb stops where torque is little bit lowered after some time which is unlikely to concern the users as a feature.

In our opinion the aspects that matter for the drivers (and what aspects we have used in our product design ) are smoothness, low cogging, low ripple, high torque response rate, and high motor efficiency which enables passive cooling (and lower power consumption) and low noise.

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So SC2 is now using in-runner type of motor, then how about small / big mige on SC1 ? I only know they are servo type, are they also in-runner type ?

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And about the heat generation in Fanatec DD testing video, I still remember it shown as around 60℃ under stress test, with two motor stick together and twist in opposite direction I believe.

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They are in-runners too :wink:

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Wrt the stress-test, one doesn’t know the torque applies to those servos under test, it could be 5nm or 2.5nm or 12.5nm…

Unless those are done against a set criteria, it doesn’t prove /disprove anything.

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I have recently done some thermal time constant experiments and math on SC2 motors.

Assuming passive cooling in room temperature, SC2 Sport motor can keep full 100% torq for 4,5 minutes and Pro/Ultimate for 6 minutes before torque begins to throttle at all.

Best thing here is that the torque will stay constant before it’s beginning to reduce. This is significant characteristic as it ensures linear and consistent force feedback. In practical racing, there is no such long periods of peak torque, so it is unlikely that torque would start throttling at all.

I hope this helps!

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Thanks for this response @Tero… :slight_smile: Very powerful and strong motors…

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Except for maybe oval racing?

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That might be the toughest case for wheel. I have plan to study & test that kind of driving too.

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What is max speed at 48v on the new motors?

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All SC2 motors can reach speed of at least 5 revs/second. Max torque depends on speed, graphing the data is work in progress.

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How is the inertia? Are they (sport/pro/ultimate) easy to spin when dead like some of the super premium direct drive servos? Not really sure if that matters but I do remember reading some of those premium servos were easier to turn and smoother when dead vs the miges

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Thanks Tero,

Can top speed be slowed down via software?
If I remember correctly back in the early days of OSW 200rpm was deemed ideal top speed?

Beano chime in if you remember this.

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The Fanatec does run daily cool but I have run it up to 89c in my running on the Beta Model I have… that being said it does have an internal fan to keep things cool… it stays pretty quiet but not always.

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Hi Joe,
I always considered 200-300rpm to be the ideal-range envelope, but the only way I could control mine back then was by either psu/voltage selection or servo choice…subsequent testing has confirmed (for iRacing at least) that it covers the preferred range

The new SC2 Ultimate will have an actual slew-rate filter to support speeding up or slowing down the servo to your preference, giving another layer of control over the ffb feedback behaviour. Tero can tell more about that one, but I am damn excited to get my hands on the new beta FW with added filtering, what I saw on that list was exciting :slight_smile:

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Hi Beano,

That sounds AWESOME!
Getting the overall speed lower is something I always wished we could do.
I will end up with an ultimate. I will let you crash test dummies work out the bugs first! :slight_smile:

No film of the Giant falling on the ice this trip to see the boys in Finland? LOL

Talk soon,
Joe

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Can’t remember out of my head, I think it would be good idea to add this info into product specs among other things asked here. They’re on our backlog :slight_smile:

Beano is right, there will be new filters to fine-tune speeds to user preferences. Filters will be somewhat experimental at start, and their characteristics will be fine-tuned based on user’s feedback.

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Will we be able to adjust speed on all 3 SC2 models?
It would be very good if we can. It makes things safer when in nasty accidents.

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At least slew rate limit is adjustable for all models.

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