read more: FFB Tweaks

[Stereo]

I've worked with x4fab to add a new feature to the Custom Shaders Patch (as of 0.1.51) and the description is fairly brief so I thought it's worth going into a bit more detail about what this does.

Gyro Implementation

[ ] Active check to enable
Strength 25% adjust effect strength
AC has an "Experimental Gyro" FFB effect whose purpose was adding gyroscopic effects to the steering. It never lost the experimental tag and all it's generally recommended for is damping down oscillations on direct drive wheels.
This is that, developed slightly further based on my understanding of the nature of gyroscopic forces. I have a pretty solid case for making this change, and I believe this force exists in actual cars, and AC's original experimental gyro does not.

The developed version still suits the purpose of damping oscillations, but more importantly it decouples the body from the front wheels - so if the front wheels are pointing in a direction and the body moves around them, no gyroscopic precession happens, and no force is generated. Concretely, what we're talking about here is oversteer - on the original experimental gyro, the force acts counter to self-alignment during oversteer. With this new implementation, self-alignment is allowed to occur freely, or, if the oversteer is so quick that the wheels can't self-align, it'll actually push in the direction of alignment.

25% is simply equivalent to the original force multiplier used on experimental gyro when merging it with other FFB forces. Ultimately, the same as the other amplification ffb effects like road and slip effect, the slider is available to magnify it if your hardware's limitations are obscuring the effect.
As of CSP 0.1.53 the strength slider is outdated. A calculation using the suspension geometry now provides the right precession-based force for each car.
The description is a little bit misleading; this replaces "Experimental Gyro" so disabling it is superfluous, if this is Active, experimental gyro is not. Still, it won't hurt to disable experimental gyro and be certain it's off.

Now that I've said what the intent is, I will also note the following: this changes FFB in pretty much every dynamic situation. It's not just an improvement for drift cars or for vintage cars that oversteer constantly; any time the car moves around on the tires it feels slightly different from before. To me, it's a positive change, it's clearer what the car is doing, and I have heard similarly positive comments from testers. Nonetheless, I am not omniscient, I have not driven all these cars in real life, it's up to you to decide whether it improves your game or gives you better sim feeling the rubber or what. Modifying games to improve the FFB is a fine tradition starting with some extremely thorough efforts in rfactor1, and this is no different (maybe a bit easier to install).

I will note that it slightly increases max forces when cornering so if you have stuff set up to barely clip, you'll need an adjustment downward in global ffb mult.

Range Compression

Range compression 100% - 100% is the "default off" of this effect
[ ] Range compression assist - check to convert cars' "steer assist" into range compression.

New FFB Tweak available as of 0.1.53. The name comes from the audio world, where dynamic range compression means bringing up the quiet sounds while leaving loud sounds at their original volume. This is a much more second derivative friendly version of the Gamma effect.

The percentage is straightforward: Set it to how much you want to multiply small forces. Or adjust it in sync with your overall gain if you want to maintain the level of small forces and change large forces. For example, 200% compression + 50% gain = original 100% on small forces, larger forces decrease. If you're curious, the curve at the point of maximum force is simply the inverse, 200% compression will cause large forces 50% of the original delta in force. But in combination with 50% gain, you're moving the original maximum force downward and the ceiling before the game clips is much higher.

Think of this like power steering: you only want it to assist the heavy forces and give you maximum feel of the light forces.

This is very much an "adjust to taste" thing, it operates smoothly enough that you're safe running it upward of 300%, and I have seen IRL data indicating that manufacturers effectively go as high as 600% in power steering systems, when they want to bring 20+N forces down to a comfortable 2-3N.

Steer assist is a built in per-car feature of AC that applies a gamma function to that car's FFB. If you check Range compression assist, then FFB Tweaks will calculate an appropriate range compression adjustment, and disable steer assist. This should give you a far more normal FFB feeling (no weird bumps around center) while retaining the original goal of giving high downforce cars enough low-speed FFB to be drivable.

 

[RasmusP]

I'll try to summarize your brilliant post into non-technical language:
A belt wheel like Thrustmaster or older Fanatec has a rather small motor with low "input to output lag", but the belt and "gearing" (disks + belt, not necessarily a gear) adds damping/friction/latency.

So if the ffb signal is hovering around the center, the little motor will follow that signal pretty accurately, but the steering wheel won't really move in the same way due to the "external", mechanical "brake" of the belt system.
Which means the ffb motor itself won't overshoot much and will stay in the center pretty well.

Compared to that, a DD wheel has very low mechanical friction so the output will follow the motor very closely.
However the bigger motor adds more latency/overshoot in the ffb motor itself.
The bigger difference though:
The filtering/damping/articifical friction is done via the motor, not via an external system.
So the ffb motor itself won't follow the ffb signal accurately enough to stay calm in the center.

The big DD has way more plus points than the difference regarding oscillations between DD and belt driven, so we all want to use a DD.


The question I'm having in my head since about two years:
Would it make sense to implement a mechanical brake system into a DD wheelbase and apply things like damping/friction/inertia not via the motor control?

I love the straight line feel of the TS-PC with its mechanical resistance that's higher when starting to turn but becomes lower, when doing fast, big steering inputs.
It's the only plus point against any DD though.

 

[oskan]

How much range compression were you using with the gyro enabled?
For me, the "new" gyro always only calmed the wheel down, like it should.
But range compression adds "gain" so when using values above the neutral 100%, you need to lower the gain to not get oscillations.
The effect is pretty massive. If my wheel is not oscillating at all when driving straight and taking my hands off, even 110% range compression can make it instantly oscillate wildly on straights.

You're then countering this via the moza ffb curve (which is an awesome feature imo).

I would recommend to lower your gain, put range compression back to 100%, enable the new gyro and then boost the first 2 points of the ffb curve a little bit to make the center tighter and go in a smooth, almost straight line towards 100% in the curve.
Move the first point a bit around until your straight line feel is tight and the wheel is moving a bit when taking your hands off and maybe even starting to oscillate, but bit wildly/violently.

My experince is the opposite, the csp gyro increases ffb and and 100+ range compression lowers it. Again talking about the downforce monster F2004. I only drive F1 cars so don't know how it feels on other cars.
I agree on range compression increasing the oscillation though. I guess that's because it's increasing the small forces which is the cause of oscillation. Now I'm using it at 100% and lowering the FFB instead.
Increasing the friction in Moza software also helped with oscillations.

 

[RasmusP]

My experince is the opposite, the csp gyro increases ffb and and 100+ range compression lowers it. Again talking about the downforce monster F2004. I only drive F1 cars so don't know how it feels on other cars.
I agree on range compression increasing the oscillation though. I guess that's because it's increasing the small forces which is the cause of oscillation. Now I'm using it at 100% and lowering the FFB instead.
Increasing the friction in Moza software also helped with oscillations.

The gyro might increase oscillations due to latency/overshoot, but it's meant to be an additional damper against the ffb from the road.
"Increase of ffb" can also be similar to the Moza friction slider. More resistance in your hands, but less oscillation. I'd need to test this to confirm though.

About range compression though:
The first post of this thread explains it. (I cut down the text and underlined a few words)

Range Compression

Range compression 100% - 100% is the "default off" of this effect
[...]
New FFB Tweak available as of 0.1.53. The name comes from the audio world, where dynamic range compression means bringing up the quiet sounds while leaving loud sounds at their original volume.
[...]
The percentage is straightforward:
Set it to how much you want to multiply small forces.
Or adjust it in sync with your overall gain if you want to maintain the level of small forces and change large forces.
For example, 200% compression + 50% gain = original 100% on small forces, larger forces decrease.
If you're curious, the curve at the point of maximum force is simply the inverse, 200% compression will cause large forces 50% of the original delta in force.
But in combination with 50% gain, you're moving the original maximum force downward and the ceiling before the game clips is much higher.

 

[Deleted member 197115]

Overshot with DD wheels is there even without Gyro, reason they are usually tweaked with extra dampening, friction, and low latency filters on servo side.
One of the reasons Kunos created "their" gyro is to overcome that issue, copied improved version into ACC as "dynamic damping" and from what I can tell Reiza is trying to mimic in AMS2 something similar with their damper which is also implemented as Constant force effect. Could be wrong but looks like R3E is on the same path with their overhauled few years ago FFB.
"Corrected" gyro feels great but completely missing that dampening effect that calms down overshot and makes SAT wheel realignment smoother instead of jerky shoulder dislocating snapping.
Kudos to modders for finding and fixing the error in the original implementation, but in its current form it's practically unusable for DD owners, leaving us with not ideal but at least serviceable stock Gyro, or no Gyro at all.
Which is fine, at least belt wheels drivers are happy, it's not all about us.

 

[mclarenf1papa]

I'll try to summarize your brilliant post into non-technical language:
A belt wheel like Thrustmaster or older Fanatec has a rather small motor with low "input to output lag", but the belt and "gearing" (disks + belt, not necessarily a gear) adds damping/friction/latency.

So if the ffb signal is hovering around the center, the little motor will follow that signal pretty accurately, but the steering wheel won't really move in the same way due to the "external", mechanical "brake" of the belt system.
Which means the ffb motor itself won't overshoot much and will stay in the center pretty well.

Compared to that, a DD wheel has very low mechanical friction so the output will follow the motor very closely.
However the bigger motor adds more latency/overshoot in the ffb motor itself.
The bigger difference though:
The filtering/damping/articifical friction is done via the motor, not via an external system.
So the ffb motor itself won't follow the ffb signal accurately enough to stay calm in the center.

The big DD has way more plus points than the difference regarding oscillations between DD and belt driven, so we all want to use a DD.


The question I'm having in my head since about two years:
Would it make sense to implement a mechanical brake system into a DD wheelbase and apply things like damping/friction/inertia not via the motor control?

I love the straight line feel of the TS-PC with its mechanical resistance that's higher when starting to turn but becomes lower, when doing fast, big steering inputs.
It's the only plus point against any DD though.

Thanks, though you did leave in technical terms (damping, friction, inertia) that aren’t what I was talking about. Main thing was actual motor torque response time, which would only be affected by damping or inertia (and the former is relatively small with belt wheels, latter probably about the same as a DD, maybe less). It’s primarily an electrical thing, not really mechanical. And overshoot etc is a result of how PIDs are parametrized, so it’s still a software thing, not something inherent to a DD wheel.

Overshot with DD wheels is there even without Gyro, reason they are usually tweaked with extra dampening, friction, and low latency filters on servo side.
One of the reasons Kunos created "their" gyro is to overcome that issue, copied improved version into ACC as "dynamic damping" and from what I can tell Reiza is trying to mimic in AMS2 something similar with their damper which is also implemented as Constant force effect. Could be wrong but looks like R3E is on the same path with their overhauled few years ago FFB.
"Corrected" gyro feels great but completely missing that dampening effect that calms down overshot and makes SAT wheel realignment smoother instead of jerky shoulder dislocating snapping.
Kudos to modders for finding and fixing the error in the original implementation, but in its current form it's practically unusable for DD owners, leaving us with not ideal but at least serviceable stock Gyro, or no Gyro at all.
Which is fine, at least belt wheels drivers are happy, it's not all about us.

Response to the end of Rasmus’s post and to Andrew’s - the correct fix is really just for wheel driver PIDs to be parametrized better (less overshoot, built-in wheel inertia measurement for proper compensation, etc). I think there’s quite a bit of innovation left in that area, and IMO it shouldn’t be the sim’s responsibility to fake its output signals so that wheels don’t have issues with it (assuming the outputs are realistic of course).

Also Andrew, SAT is a specific thing with tires (and only one component of the overall steering force), not sure if you actually mean SAT or if you’re just talking about torque snap back, which is a usually a function of bad user settings (not enough friction/damping/inertia. People tend to run way less than actual measurements of these quantities) or a bad car in the sim. Best to use a different term to describe it if it’s not actually SAT.


Another fun test people can do is see what oscillation is like with different steering wheels attached. Different inertia on the column changes the frequency of the system, so you get much more violent and fast oscillation without a wheel than if you attach a large wheel. Ideally the driver would have an option to measure the load inertia and adjust its controller parameters accordingly (as to optimize its response).

 

[Deleted member 197115]

Also Andrew, SAT is a specific thing with tires (and only one component of the overall steering force), not sure if you actually mean SAT or if you’re just talking about torque snap back, which is a usually a function of bad user settings (not enough friction/damping/inertia. People tend to run way less than actual measurements of these quantities) or a bad car in the sim. Best to use a different term to describe it if it’s not actually SAT.

May be there is different term, but this is what we used in OSW/SC group for quite long time, doesn't mean it's correct.
When tires regain traction after slide, wheel tends to violently realign which can be quite brutal at high torque settings, yes, extra damper can slow it down, but it also affects overall wheel response and dampen details. Which is why gyro was preferred method to deal with this condition.
GamerMuscle whether you like him or not had that old video explaining effect of Dynamic Damping (ACC Gyro).

 

[mclarenf1papa]

but it also affects overall wheel response and dampen details

Not in an unrealistic way though, was my particular point. Since AC doesn’t model any damping/friction/inertia internally, it needs to be added via the driver for realistic response. Of course, that will feel less “detailed”, but it’ll be more accurate (and happy side effect is lower oscillation).

SAT in the context of a car is tire FY*pneumatic trail (ie the amount of steering torque from the tire alone, irrespective of steering geometry). Around peak slip angle, SAT goes to ~0 (or even negative, ie pro rotation) and the primary steering torque is created by mechanical trail*tire FY. Hence distinguishing actual SAT from overall steering torque can be important depending on conversation context.

 

[Deleted member 197115]

Isn't that increase of the steering torque is the result of SAT, i.e. tires trying to realign with the direction of car travel? At least in layman terms.
And simulating "realistic" FFB as in respect to real life steering rack forces and dampening is futile exercise as we do not get G and SOTP forces in our sim rigs to get the full picture, so exaggerated FFB is the only sensory input we get, in addition to visual feedback.
Of course we all can have different opinion on that, but that is common trend all sim developers follow implementing FFB.

 

[mclarenf1papa]

Isn't that increase of the steering torque is the result of SAT, i.e. tires trying to realign with the direction of car travel? At least in layman terms.

Not necessarily, SAT near optimal slip angle is very low; on a car with any mechanical trail (caster trail), the force from that will be much higher than SAT near peak slip (and probably much higher than SAT in general). Below that, you get a mix of SAT and FY*mech trail. Snapback is generally the tires going through their peak torque slip range (slightly before FY peak as it's before SAT drops off, but FY is also near peak).

And simulating "realistic" FFB as in respect to real life steering rack forces and dampening is futile exercise as we do not get G and SOTP forces in our sim rigs to get the full picture, so exaggerated FFB is the only sensory input we get, in addition to visual feedback.
Of course we all can have different opinion on that, but that is common trend all sim developers follow implementing FFB.

There are a lot of opinions about this, but part of the problem you'll run into is that not using actual steering torques will also not realistically limit certain things. Sims are generally too easy to drive with a hyperactive DD wheel, and I don't buy that people need all of that feedback to supplement not having G forces; people are very fast with G27s or even mouse and keyboard. Niels Heusinkveld has mentioned this a few times as well, real steering helps the driver much less than what your typical sim racer might set their wheel to. I get that it's nice to have additional feedback, but it should be done through more appropriate channels (buttkicker, etc) IMO. Leave the stuff accurate that you can actually make accurate, or if you're going to deviate, deviate all the way, don't make it "sort of rack forces, sort of not". Without appropriately-set damping/friction/etc, wheel speeds and peak torques can get way higher than would be possible in real life (which you mention as an "issue" re: snapback and oscillation). So it's a bit of just getting what you're asking for when you begin to deviate from the real system.

I get the premise, but real cars are designed very specifically around steering behavior, so making that no longer align to real life is also changing the accuracy of the sim model. e.g. (in the other direction), it's hard to drift a car with a g27 when it has accurate tires because the g27's peak torque is too low to spin the wheel quickly enough. That's artificially making the car drive differently as you need to put in different inputs to get the same output as someone with a realistic wheel.

IER goes through the trouble of modeling the power steering for our client cars, as differences in the steering vs the real car can make it feel as though it drives very differently.