Like your FFB strong? Think again..

Niels_at_home

Reiza Studios
Heyas,

I've been around this simracing scene now forever and it seems the vast majority of folks like to run very high force feedback settings. Then you often read claims how great it feels and how they can even feel the effect of flies building up on the windscreen through these FFB settings (sarcasm = on). Some even feel when the coffee is done in the kitchen (sarcasm = still on)..

Force Feedback talk
Good sims will use complex physics engines to calculate the force feedback. Part of the feel is the tires, part is the suspension geometry, and this all changes with steering angle and things like how much weight (load) is on the tires.

If you'd only feel the tire part of the force feedback, the forces would be near ZERO by the time you've applied the optimum steering angle to get maximum grip. Thats just how tire physics (pneumatic trail) works, give or take some margins. Counter intuitive eh, but its often near true!

Suspension geometry usually adds a chunk of force, but still it is higly likely that the force you feel in a racing car drops off after a certain amount of steering and by the time you've applied the optimum steering angle for max grip, force through the steering wheel might be about half of the maximum.

That means when the steering goes light in a racing car, you might not be understeering at all, you might be right at the maximum grip levels!

Problems with sims
Even when your favourite sim has good tire and suspension physics, that doesn't mean your wheel (G25, Fanatec, Thrustmaster etc) will behave properly. The physics engine will just calculate a torque or a steering rack force, perhaps during a lap this value is between 0 and 5000 Newtons.

At some point the sim will have to tell your FFB steering wheel what force it has to apply. You can imagine there is some scaling required. Ideally the 0 .. 5000Newton that occur on the track should be the range where your FFB wheel responds between 0% and 100% of its capable force.

This scaling is NOT DONE AUTOMATICALLY by iracing / LFS / rFactor&Realfeel !! You have to scale this yourself. In iRacing and LFS its the force feedback strength in the menu, with rFactor&Realfeel there is the realfeelplugin.ini 'Max Force' entry to adjust.

When you scale the forces down too much, you get weak force feedback. When you don't scale them down enough, you're asking more from your wheel than it can do, so at some point the forces will be trimmed. This is called 'clipping'. If your wheel has a maximum of 100, you can't make it do 200. So anything you ask from it above 100, you won't feel a difference.

First chart: Scaling the force feedback

ffb1.png

The blue line is how a good simulator might calculate the force feedback strength versus your steering wheel angle. It is what it *wants* your FFB wheel to do.

Lets say proper scaling means you have to run the ingame FFB strength at 20% which is not uncommon at all. In this example, 20% strength matches the maximum occuring force feedback of the physics engine to the maximum feedback your wheel can put out.

If you'd use 100% ingame FFB strength, you would only have a small part of the desired curve fit below that line. That is bad.


Second chart: Results
ffb2.png


This chart is the results; what YOU feel on your wheel. You can see that running 100% FFB strength tries to make your wheel 5x stronger than it really is. It just can't do it, so you feel the red line. Apply steering, forces max out *very* quickly, and as you steer more, the force stays maxed out. It hasn't got the power to follow the desired dotted line. This is what many simracers do probably without knowing it. The force feedback isn't detailed at all, its almost on/off.

The green line is what you get with proper scaling. It follows the desired shape exactly, but now with the maximum occuring force nicely matched to your wheels maximum deliverable force.

Now why does 100% still feel stronger than 20%, despite the maximum force being the same? At 100% you have to grip the wheel like mad because any slight bump or minimal steering will result in maximum force. Once you're steering, the forces are mostly constant, but going near straight you feel strong jolts left/right as micro bumps / steering inputs cause these forces. Wheels setup like this are often unstable and will oscillate when you let go of the wheel on the straight. For some reason lots of folks think this feels good.

So how do I set this up correctly then?
Thats the hard part. Even on the same car if you change the car setup (caster, downforce) the numbers will change. On a flat street circuit the values will be different than in a fast banked oval.

Realfeel with rFactor is the easiest, you can drive the car on a track, look at the telemetry, and the 'Steering Arm Force' that you see in a hard corner is your desired Realfeel.ini "MaxForce" entry. Don't look at short spikes of force, go for a sort of average force you see in a fast bend.

With other sims its a matter of getting a feel for what your wheel can do. Once you know what its maximum strength feels like, lower the ingame FFB strength until you clearly are below this maximum force. Then add force slowly until you get to the point where it seems saturation occurs. I can't help much, the FFB strength will typically be between 1% and 100% :S. Try the maximum force in a steady corner, because on a straight, the sudden left/right jolts of too strong force feedback will make it feel subjectively stronger than it is.

Conclusions?
Current wheels like the G27 are fairly weak; they can't really deliver a strong force. It is very easy to try and ask too much from the wheel. It might also lead to overheating and faster wear!

I've tried to show you what force feedback scaling does and how running too strong force feedback settings can numb down the detail you feel, even when it *seems* like the effects are nice and strong.

Everybody is free of course to use whatever setting they like, but at least this shows that people running very high FFB strengths claiming they get lots of detail and a good feel for the car, are wrong from an objective point of view.
 
There's a FAQ on LFS forums suggesting to set the FFB in the Logitech profiler to 101% or more - because having it under 100% gives reversed FFB readings. Is this true?

Values below 100% does not give reversed FFB readings from lfs, but cranking the value over 100% makes the ffb do the smaller forces around the center of rotation better, like the logitech profiler isn't linear until set over 100% value
 
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To explain the problem, Mizoo who made an FFB card, can make telemetry screen of FFB effects with the Leo Plugin. Mod used DRM, car BmwM1...With his card used...

With Relative strength of FFB effects= 1.1 and Road bumps feeling on the wheel=0.4 and FFB in Rfactor 100%, in the screenshot 100% of the force=10 000

testcs.png


You can see that all the effects are used. With an Happ motor and the AMC we can have enough force on the wheel...

With strength of FFB effects= 5.2 and Road bumps feeling on the wheel=5.2 recommended by the Team DRM...For the Logitech wheels etc...

testht.png



We loose a lot of effects...
 
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There's a FAQ on LFS forums suggesting to set the FFB in the Logitech profiler to 101% or more - because having it under 100% gives reversed FFB readings. Is this true?

Having read this thread I changed my logitec profiler to 100%. The steering went very strange in iracing... like there was a super fast sterring rack and a very strange end to the travel at like 90 degrees... horrible.
Read your post Bullhorn and changed it back pdq, all good now.

I dont understand the graphs above at all....
George
 
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George: the values on the graph are the force values sent by the games (time on X axis), positive value is a force to the left, negative one is to the right direction.
+/-10.000 is the max value that can be used by the game (DirectInput constant), all above is "clipped".

Changing the FFB strength in rFactor option doesn't change anything, it's just that the clipping value will be lower (there are such graphs on my thread).

Note: it's totally hardware independent, valid for any steering wheel.
 
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Yesterday, I did some tests with Game Stock Car demo, here is the FFB monitoring result (track curitiba):
testcm.png


As you can see, clipping is present with the default setting, the realfeel configuration file has to be modified to avoid this (increasing the MaxForceAtSteeringRack value).
 
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More to the point how many people have NO idea how to set their Logitech Profiler and actually have it running While in rFactor for instance. To high a FFB Strength is why so many have breakdowns with their wheels.
IMHO you MUST set your BASE line in the Global and NOT allow the game to change anything and then every other profile made AFTER that point will be a percentage of the Global base.
The FFB varies with mod to mod as well and this is also rather frustrating , this is actually why I have several real Feel Control ini files that I swap in and out depending on what mod I am using at the time.

For instance my FFB Global is

Overall Effect Strength = 115%
Spring Effect Strength = 50%
Damper Effect Strength = 150%
Enable Centering spring = 50% (ticked)
Steering Wheel Deg of Rot = 900
DO NOT allow Game to control Settings
Why because GTR will make a setting and then LFS will make a setting and pretty soon you have an unmanageable mismash.
This is why you create individual profiles based on the Game played.

rFactor settings

Use special FFB Device Settings (ticked)

Overall Effect Strength = 75%
Spring Effect Strength = 12%
Damper Effect Strength = 150%
Enable Centering spring = 20% (ticked)
Steering Wheel Deg of Rot = 900

Use Special Game settings and allow game to adjust settings.
Then select the Steering wheel in the profiler and edit the Axis Properties to 100% Sensativity 0% Deadzone and 100% Range.
Later set the Deg of lock in rFactor and make damn sure that the sensitivity is 100% in rFactor with 0% speed sensitivity on the steering axis.

If you have issues with the Accelerator then drop the Sensitivity to 0% with 10 % Deadzone and 100% range
I use a Hydraulic load cell mod I made to my G27 and can run the brake at 100 0 100 and rarely lock the brakes,depending on the Mod.
The combination of these settings and reel feel I can literally feel little bumps and ripple strips and the steering goes light when I lock brakes and or get the car very light or airborne even, too high a FFB settings can contribute to sensory overloading of the driver and also poor vehicle control as a result of trying to fight the wheel.
My driving has improved dramatically since I have employed the above settings.
 
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I'm sorry but your settings are a good example of how not to set your Logitech G2x wheel up from a sim point of view. Overall strength might benefit a bit from more than 100% but as soon as you use >100%, you must lower in game FFB or it will start to clip.

Tweaking your game FFb strength, say you find 50% in game FFB strength to maximize the use of your FFB wheel without clipping. If you then set your logitech panel to 120% overall strength, your in game strength has to be lowered to 41.7% (50 / 1.2)!! Don't mistake increasing the overall strength with an increased center 'feel'. Perhaps you're just causing clipping in a different way.

Damper effect at 150% can be silly depending on the game. Most sims don't even use the damping, but previously with iRacing that would have completely destroyed any feel. Logitech wheels feel damped on their own so typically no damping is required.

This would be a normal logitech setup:

Overall Effect Strength = 100%
Spring Effect Strength = 0%
Damper Effect Strength = 0%
Enable Centering spring = 0% (ticked or unticked doesn't matter)
Steering Wheel Deg of Rot = depends on the car you're driving.


Ideally you'd go for no clipping but the G2x type wheels are very weak in FFB. With GSC we kinda deliberatly added clipping as it would just feel better to the majority of players. Others are free to tweak the realfeel max force value for a seemingly weaker FFB without clipping. :)
 
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Yes, LFS, realfeel & leoffb plugins don't use damper and spring effects, adjusting them has no effect.

As you said, G2x is really not powerfull enough, you have to choose between having all magnitude of force feedback but with really soft feeling, or increase the strength and having lot of clipping. That's why we (stef bord, me and others guys on RFR forum) use more powerfull steering wheel (based on arcade material) and, trust me, that makes a lot of difference (niels, you know what I mean with your servo driver ;)) !

And, be carefull, decreasing the in game FFB strength doesn't avoid clipping, it just decreases the maximum force value (it set the device gain, Direct Input terminology), clipping is still present.
Example: effect strengt set to 64% in rfactor (with stock settings):
testcz.png


And with 100%:
testfm.png
 
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And, be carefull, decreasing the in game FFB strength doesn't avoid clipping, it just decreases the maximum force value (it set the device gain, Direct Input terminology), clipping is still present.

Yes indeed, for rFactor / GSC / Realfeel, you want to adjust the realfeel.ini MaxForce value, higher value = less clipping. Lower the setting in the game and you will still get clipping as Mizoo perfectly showed. :)
 
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Niels, THANK you for the ability to always aim to be as real as possible, and then share your knowledge with the rest of us!
I bought the Game Stock Car only because of the video's you have on your youtube channel, and it has not dissapointed me ;)

But I have to say Thank you and Damn you at the same time. THANK you for be part of a great sim, and you seem to set realistic over speed, in terms of steering wheel rotation, stick shift instead of paddle etc. But DAMN you (and Remco) for making me a DIY addict. After seeing you guys drive with DIY equipment, and especially you 'Game Stock Car Driver Camera' Video "forced" me to make my own loadcell pedals. (Offcause, Sarcasme is VERY much on right there! ;) ) The Pedals have been gold so far, and adds so much to the realistick feeling, and a little to speed perfomance.
Its just my girlfriend who doesnt like the time, space and money I use on the now ongoing cockpit project.
But then again, who have asked her, about her feelings? ;)

Now this thread once again show your great technical insight (and Mizoo's too it seems), and that it very informative info. I myself have been struggeling in the aim to get the real feel of the wheel, cause I have never felt the G25 to be real. In real live I race in a Classic 66 Mustang hardtop, a historic 87' Reynard Formel 2000 and can sometimes be found at drifting events. I have tried to feel how it should feel, but have never felt it with the G25.
I know the G25 is just a hobbyist wheel, and way to underpowered to deliver something just near the real steering wheel forces (especialle for the formel car with downforce and no power steering), but its not force I have been aiming to reach, I now it cant be done with a low budget wheel, but its the Feel of the wheel I wanted, being able to drive with the feeling I get through my fingertips.
Now I know why I havent been able to do so, and now I just CANT WAIT to get off work, and get home and try for myself :)

Thank you so much Neils and Mizoo, you guys helped me out a lot right there.

Mizoo: You are saying you and some of your friends drive with some arcade material based, but more powerfull steering wheels.
Do you have any pictures of them, you could link to? Sorry, but as said before, Im now a DIY addict ;)

Once again, thank you guys for taking the time to share you knowledge with the rest of us! :)

Kasper Stoltze
 
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Values below 100% does not give reversed FFB readings from lfs, but cranking the value over 100% makes the ffb do the smaller forces around the center of rotation better, like the logitech profiler isn't linear until set over 100% value
Is this for LFS only? I am always using 101% for almost all games for as long as I can remember. Picked it up once and have never adjusted it (with exception of one game).
 
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Thanks for the answer. I'm pleased I managed to understand that much! On the auto-scaling, it seems to me this is analogous to producing music, where with production software you can define a frequency envelope within which the signal is scaled. Applying that idea to the driving wheel, if you want the raw linear signal as a default, fine, but as an advanced option it seems to me some sort of logarithmic envelope would give the driver a tighter, more comfortable wheel for zero newton straights, while still producing the much tighter feel at 5K newtons, without ever resorting to clipping.

More like compression or limiting used in mastering music where the quitest passages are made louder and the louder passages quiter which creates a clipping effect and destroys the dynamics and air of music.You can tell when this effect is on by the muddy ,messy,distorted quality of the production and by looking at your metres.With over compressed music,they hardly move.All in the name of being louder on the radio.Progress?What progress?
 
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