AccuForce torque ripple developing after 30-45min

[Shovas]

This is about an extremely well used original AccuForce V1 that I've had and used continually since 2015. Don't worry if you're thinking about getting a new AccuForce. They're tanks and well supported by SimXperience (see Berney's snipe post right after my original post) for how well they support their product. They're great.

Solved: The encoder cap (and therefor the encoder board/sensor hard-mounted inside the cap) on the rear of the motor had tiny amounts of play and was likely getting knocked out of calibration by vibrations from ffb. My DIY solution was to secure the cap. My choice was a rather generous length of packing tape (because of its stickiness and robustness) that stretched along the sides of the motor and over the cap to hold it down (from moving in and out possible) and to prevent it from rotation and up/down/left/right movement. This solution will likely deteriorate over time and I will need to come up with a new solution. A possible option at that time would be a few dabs of hot glue. I hope this helps other AccuForce owners in the future.

[Solved] AccuForce V1 2015 - torque ripple develops

I've been experiencing progressively strong torque ripple (or cogging or bumps when rotating the wheel) that seems to occur simply with usage about 30-45min after powering on and using. The problem is actually strong enough that it affects the ability to input rotation accurately to drive cars.

Has anyone else experienced this and do you have a solution?

I originally thought it was due to in-game car crashes that sent the AF wheel flying around (I let go) causing some kind of miscalibration / out-of-alignment issue. Maybe due to the brushed motor design??

But the problem seems to be occurring within 30-45min of powering on and using the wheel regardless of how the wheel is used.

I was recommended by SimXperience support to power off the wheel for 30sec and power back on. I've tried longer periods (ie. over night) - no luck. I also found SimCommander's device "Reset and Calibrate" helped somewhat/sometimes. Neither of these fixed the issue completely.

I've tried restarting SC, updating SC, reapplying device defaults, power cycling the AF, power cycling the computer, etc. nothing has worked yet.

The problem is severe enough that I'm considering a new wheel and, I hate to say it, because SimXperience is a good company otherwise, but if I did have to do that it probably wouldn't be with SimXperience again.

If I can solve the problem myself I'd remain a happy SimXperience customer.

For background, it's an AF V1 I've had since 2015, so I have gotten my bang for buck out of it, but it is a shame it's developed this kind of issue. It feels like something that should be fixable.

Really appreciate if anyone can help me solve it.

Thanks

 

[Neilski]

Hmm, sort-of sounds like an overheating issue but you're saying it's independent of how hard the wheel is used for that 30-45 minutes, so possibly not (or maybe it's a component that warms up the same amount
regardless of what the wheel is doing - e.g. a voltage regulator on a logic board).

You say overnight isn't enough, but I'm still getting the impression that the problem does go away (only to show up again after another 30+ minute session), so how long does it have to be off for before the issue clears itself?

Stepper motors are a bit different from "normal" motors, which is probably playing a role in how the problem is manifesting.
Do you have enough electronics knowledge and kit to monitor the current on one or more of the main wires to the motor? If you own or could borrow an oscilloscope and check how the waveform looks at the start and then when the problem shows up, it might give the manufacturers a clear pointer to the cause.

 

[blekenbleu]

I've been experiencing progressively strong torque ripple (or cogging or bumps when rotating the wheel) that seems to occur simply with usage about 30-45min after powering on and using.

This is totally a guess: the AccuForce motor has been described as a hybrid stepper, which means that
it is basically two steppers sharing a single shaft, with one rotated half a cog from the other:

If any solder joint or connection in one motor winding and its driver circuity in the controller is cracked, corroded
or otherwise intermittent, then you could be experiencing cogging by half the motor.
Two "easy" ways to troubleshoot:

1. swap motors and controllers between yours and a known good, see which the issue follows
2. hook a current probe and oscilloscope on power wires between motor and controller

 

[Shovas]

You say overnight isn't enough, but I'm still getting the impression that the problem does go away (only to show up again after another 30+ minute session), so how long does it have to be off for before the issue clears itself?

You're right. If I leave it powered off long enough when I first start it up it's smooth again but develops the problem over the next 30-45 minutes.

 

[Shovas]

I'm in touch with SimXperience support now and sending photos and videos. They think it's the optical encoder getting dirty or something.

 

[Shovas]

Two "easy" ways to troubleshoot:

1. swap motors and controllers between yours and a known good, see which the issue follows
2. hook a current probe and oscilloscope on power wires between motor and controller

Thanks, that visual and explanation was fascinating.

Unfortunately, I don't have an extra motor or an oscilloscope. Guess I'll just wait to see what SimX support says.

Thanks anyway

 

[blekenbleu]

I don't have an extra motor or an oscilloscope

PC sound card oscilloscope

 

[Shovas]

An update,

I've been trying everything possible on my end to diagnose and solve the issue. It's out of warranty so why not. I just have this deep feeling it's something very fixable.

I suspect it is vibrations upsetting the encoder. So, last night I did the least invasive, but most incredible hack job for such a nice piece of equipment, and used wide packing tape to 'secure' the encoder cap as it had very tiny play I noticed under gentle handling - I suspected vibrations may be moving it around and causing it to get out of calibration.

So, to summarize, the wheel powered up and felt incredibly smooth. I started ACC and everything felt very smooth. About 5-10 minutes in a very small amount of torque ripple became apparent (say 5% of max I've ever felt) but still very enjoyable. About 30min later, and now in GTR2, I noticed a bit more torque ripple (say 5-10%) but again still very enjoyable. About 30m later, and now in Race 07, I noticed slightly more torque ripple (say 10-15%) but still enjoyable. 1h30m later in GTR2 I had an abnormally sharp in-game car crash and I wasn't holding the wheel very tightly and that's when I noticed a jump in torque ripple (say 15-20%) but still tolerable, a little annoying, but very livable (not as enjoyable as before though).

To be clear, this result, 15-20% of the aggressive torque ripple from the last test, is actually a much better result than I think I would have gotten if I hadn't secured the encoder cap. Without that change, I would have expected unplayably aggressive torque ripple by the end of the testing. I believe the tape securing hack job has improved the situation for now, at least until it deteriorates and no longer securely holds the encoder in place.

Update (July 2023): I wanted to highlight for the above that a more secure/permanent cap mounting solution (ex. hot glue) would probably have alleviated even the minor torque ripple noted.

All that said, I need to repeat a couple more extended sessions to confirm securing the cap is actually helping.

If it is helping, I will try to think about how better to secure the cap and see about reducing vibrations and movement through my wheelbase which is hard-mounted on an Obutto R3volution but there is still some play (and I can only bolt in on 2 front bolts so the rear has up and down play).

For those interesting, here are some high quality, well lit photos and videos of my unit while I've been investigating:

https://1drv.ms/u/s!AqWsLwV2vzN8qjF-UVGltpqJchsd?e=5kJA6u

I haven't cleaned anything up so I don't think it's likely lubricant contamination is the cause. Regardless, I used compressed air on the encoder housing (which looked spotless to my eye) just to be sure.

 

[Shovas]

I'm mainly tracking this over on the iRacing forums where Berney (owner of SimXperience) frequents and I'm able to get his input so I'll try to keep this updated, too.

 

[Shovas]

This is about an extremely well used original AccuForce V1 that I've had and used continually since 2015. Don't worry if you're thinking about getting a new AccuForce. They're tanks and well supported by SimXperience (see Berney's snipe post right after my original post) for how well they support their product. They're great.

Updated the post to be clear this is about an old well used, V1 AccuForce from 2015, that has started to develop issues, and not about new AccuForce V2s.

 

[Shovas]

Good: Second extended multi-hour session resulted in 5-10% torque ripple by the end which is still great (better than the last session) and very enjoyable. It indicates to me that the fix to secure the encoder is working and vibrations are likely the issue.

Still need to repeat an extended session at least once more to be have a decent level of confidence in the root cause.

 

[blekenbleu]

photos and videos of my unit

Thanks for those; photo 12 of 18 shows a round, rear encoder black plastic cap separated from its mount with ears
screwed to the back of the motor (photo 14 of 18), which appears to be of a different (blue) plastic.
Having neither forced nor disassembled my encoder, its cap and mount appear to be all of the same black plastic, molded or glued together...

Updated the post to be clear this is about an old well used, V1 AccuForce from 2015, that has started to develop issues, and not about new AccuForce V2s.

Thanks for the updates; so far as I can determine (mostly based on scrutinizing Sim Racing Garage videos),
motors are unchanged from V1 to V2, rated 1.8 degrees per step (or 200 steps per rotation), while encoders
are 1000 per rotation, giving firmware 5 increments per motor step (0.36 degree) to tune out cogging.

I'm mainly tracking this over on the iRacing forums where Berney (owner of SimXperience) frequents and I'm able to get his input so I'll try to keep this updated, too.

Based on his 30 Sep response in the SimXperience forum (I'm not an iRacer),
perhaps he unaware that your encoder has one of those earlier two-part snap-together encoder housings..

 

[Shovas]

Thanks for the info, your context is very informative.

Definitely watched Barry on SRG a bunch to tear this down. He didn't cover taking apart the encoder on the V1, though, although he did on the V2.

Berney has seen those photos and videos and I did describe how they snap together and separate so I think he's aware. He even mentioned that if I really wanted to try to fix it myself that I should try minimal hot glue to of the cap to the base. I might try that later on.

Regarding "5 increments per motor step (0.36 degree) to tune out cogging", is this too much or enough to tune out cogging altogether? Is it the reason I feel very, very subtle "bumpiness" even when perfectly calibrated?

 

[blekenbleu]

He even mentioned that if I really wanted to try to fix it myself that I should try minimal hot glue to of the cap to the base. I might try that later on.

Would doing that to your encoder preclude non-destructively disassembling it in the future?

Regarding "5 increments per motor step (0.36 degree) to tune out cogging", is this too much or enough to tune out cogging altogether? Is it the reason I feel very, very subtle "bumpiness" even when perfectly calibrated?

5 increments per step precludes perfection.
With a nearly new DIY V2, solidly bolted by its 4 front motor mounts and naked rim directly attached,
cogging is fairly clearly felt when slowly turning that rim while driving the Skid Pad mod in Assetto Corsa
with these settings:

Otherwise, cogging may be mostly masked by road effects.
The AccuForce Pro motor housing mounting scheme pretty much unavoidably introduces a spring constant,
which combined with a lot of rotational inertia in the steering assembly may introduce confounding resonances.

 

[Shovas]

Would doing that to your encoder preclude non-destructively disassembling it in the future?

Yes, it wouldn't ruin the cap and would be outside the cap. Just a drop of glue, I would think.

5 increments per step precludes perfection.
The AccuForce Pro motor housing mounting scheme pretty much unavoidably introduces a spring constant,
which combined with a lot of rotational inertia in the steering assembly may introduce confounding resonances.

This 'spring constant', what do you mean by that?

I was rewatching Barry's review with the 5 testers again and one of them mentioned something like a 'centering spring' or spunginess to the strength of the wheel. I think I know what he's talking about it. It's like the forces don't have enough "solidness" behind them. It's hard to explain. I could say they don't have enough strength behind them but that's not true, either, it's like there's something in the force that feels elastic or something like that.

 

[blekenbleu]

This 'spring constant', what do you mean by that?

Right, you have a V1 with rigid wheel base.
The V2 Pro motor housing stock mount is less than rigid;
the wheel can bounce a bit, particularly if the steering shaft is extended.

it's like there's something in the force that feels elastic or something like that

Some cars have peculiar suspension settings, including excessive toe-in that I typically reduce to nearly zero.
I generally prefer a fair amount of self-centering and dialed as much caster into my real track cars as was possible without tearing things up too much.

 

[Neilski]

Glad to hear things are improving!
The pics seem to show a damaged/broken retaining clip, but it's hard to believe that that could make much difference, once the screws are secured. The fact that the behaviour has changed at all with the tape on is rather puzzling, for the same reason. It might indicate that there's some rubbing going on, where there is meant to be perhaps only a "nearly but not quite touching" setup? Or perhaps the motion of the encoder housing relative to the motor is purely to due to the shaking of the whole assembly.
The screws are clearly going to prevent any significant net movement (relative to the motor), but perhaps a little bit of flexing is occurring, and thus accentuating the torque ripple. Whether or not the glue would have the same (damping?) effect as the tape is tricky to predict...

 

[Shovas]

Update: I've put in two more sessions and am pleased to report no more than 0-5% torque ripple which results in a very good experience and makes for very enjoyable use. During driving, you almost forget it's there. It does increase with the strength of the ffb (eg. mid corner high ffb strength) so it's noticeable there but it doesn't detract too much from the experience. I wish it wasn't there at all but what can you do.

I have quite a bit of confidence now that even the tiny bit that the encoder/cap was able to shift (honestly like a millimetre if that) resulted in the torque ripple issues.

Now that I've got that more secure, I'm not experiencing the unplayably aggressive torque ripple that was developing before as I used the wheel in a session.

 

[Shovas]

Glad to hear things are improving!
The pics seem to show a damaged/broken retaining clip, but it's hard to believe that that could make much difference, once the screws are secured. The fact that the behaviour has changed at all with the tape on is rather puzzling, for the same reason.

I noticed the broken clip, too. Definitely hard to believe such little play (under 1mm I think) could cause such a problem but apparently...

The flaw in that cap design is the screws only screw in the base of the cap and the other half of the cap (with the encoder hard mounted inside) snaps on to it so it doesn't benefit from the rigidity of the screw mounting.

It might indicate that there's some rubbing going on, where there is meant to be perhaps only a "nearly but not quite touching" setup?

I eyeballed shaft encoding plate thing vs the encoder board for just that thought but I was pretty sure it had decent clearance.

Or perhaps the motion of the encoder housing relative to the motor is purely to due to the shaking of the whole assembly.

This is what I think is happening.

The screws are clearly going to prevent any significant net movement (relative to the motor), but perhaps a little bit of flexing is occurring, and thus accentuating the torque ripple. Whether or not the glue would have the same (damping?) effect as the tape is tricky to predict...

Good point about the glue. I've done so much disassembling and reassembling I'm not too enthused about messing with the tape as long at works. I'll have to do it eventually as it will deteriorate but until then I should be able to enjoy driving.

 

[Neilski]

The flaw in that cap design is the screws only screw in the base of the cap and the other half of the cap (with the encoder hard mounted inside) snaps on to it so it doesn't benefit from the rigidity of the screw mounting.

Oh boy, yes indeed. I checked the pics again and I see what you mean - rather questionable design!

I noticed the broken clip, too. Definitely hard to believe such little play (under 1mm I think) could cause such a problem but apparently...

Regarding the amount of play, if it's flexing in a way that moves the optical head radially relative to the encoder disc, no sweat. If it's moving in the other direction - along the circumference of the disc - then I think 1 mm is a pretty big deal indeed, given the size of the disc. From the pics, I'd hazard a guess that the distance from the optical head to the shaft is around 15 - 20 mm. With a 1000 step encoder (as mentioned above), 1 mm of movement is in the ballpark of 10 steps or 3°.
Glad you've more or less nailed it now!