Force Feedback Tweaking Guide for Simbin Games

Julien Regnard v1.0

Disclaimer (a tradition as soon as it deals with hardware): I assume no responsibility for any damage. Don't forget that the energy you spend turning the wheel always end mostly as friction heat and gears ageing. Too strong and jerky FFB will shorten the life of your wheel.

Why
Recently I was lucky to buy a G25, and I wanted to configure FFB in GT Legends for it, as there is no preset for G25. Quickly it appeared that the only thing I could do was to download and test various setups other people did or to change randomly FFB parameters until I was satisfied. As the setups I downloaded didn't solve the problems I had with GTR2 (FFB spikes on every track polygon when turning hard with Porsche) I finally had to change the parameters. This way I finally managed to understand better the role of each FFB parameter in PLR files, and I discovered that the FFB setup accounts for a very large part in the sim. A good setup can make a sim feel more realistic, or easier to drive, and a bad setup can ruin it, or even give the impression the physics model is wrong or limited. There are so many wheels, with different motors, different linearity, different lock-to-lock angle, and so many drivers with different taste that default FFB setups can feel good only for a minority.

FFB is a matter of taste, everyone has it's own setup, I hope this guide will help you to find quickly a setup that fits your taste and your wheel. Personnaly, I wanted to find a setup that feels more like a real wheel (even if it means slower laps) rather than a "magical" setup to go faster.

The most important, steering force:
How the tyres are pushing the wheel through the steering column. With this force you can feel how the car weight is "moving" from one side to the other, and back to front, and road holes, bumps, grass, 3D strips...

This is the most important thing, even more than grip, because this force will warn you before grip is lost, and you will feel where car limits are.

This force countersteers when the car is oversteering, brings the wheel in line when you let it turn.

tyre grip:
In Simbin games, tyre grip is massively exagerated in FFB and added to cornering force, to make the wheel loose when you have lost grip. This helps to understand quickly what are the grip limits of a car, but it often masks very valuable information like slight changes in steering forces.

steering column Friction and Damper:
All steering columns use a steering multiplication, and sometimes a power steering assistance. It helps the driver a lot, and it makes the steering less direct.

Friction and damper FFB allow you to simulate this effect. This is not calculated by the physics engine, just FFB. And it can entirely change how the sim feels !!

This is what gives steering column a mass, some inertia, makes it loose or very reactive, realistic or not. Without friction and damper the wheel is as light as the internal FFB mechanism allows.

additional FFB-candy:

 * brakes vibration: vibration added when you brake. Helps you to feel how strong you brake, as the vibration slows down with car.
 * throttle vibration: vibration added when you accelerate. Helps you to feel how strong you accelerate, as the vibration accelerate with car.
 * steering vibration: vibration added when you turn.
 * strips vibration and force: vibration and force added when a tyre is over a strip, as some strips are not physical objects, but textures generating no forces on tyres.
 * jolts: FFB spikes when you touch another car or a wall.

Low
steering force (steering+grip)

Medium
steering force+ damper+ friction+ strips rumble

High
steering force+ damper+ friction+ strips rumble+ brakes vibration

Full
steering force+ damper+ friction+ strips rumble+ brakes vibration+ throttle vibration+ steering vibration

FFB parameters
For GTL, GTR2, FFB parameters are in each player setup (.PLR files). You can find these files in the folder UserData/*UserName*.

For WTCC Race, FFB parameters are in a .rcs file located in UserData/ControlSet. The file is named like the controller setup you choose in game (for example “Logitech G25 Stick shift.rcs”).

When you change these parameters, don't forget to make a backup copy of your PLR (or rcs) file. If you chose a FFB preset in the game, it will override all changes you made previously in the file.

FFB parameters are at the end of file.

Here is a list of the most important parameters with their role (what I think I understood with some tests and experiments, it may be wrong but is seems to work as expected):

Global parameters

 * FFB Effects Level="4" // Number of FFB effects to use: 0=No Effects, 1=Low, 2=Medium, 3=High, 4=Full, 5=Custom.

If you set it to 1, you just have cornering and grip forces. Other levels activate artificial vibrations. Parameter present in game UI. See 2.B.


 * FFB Gain="0.66000" // Strength of Force Feedback effects. Range 0.0 to 1.0. This is overall FFB strength, parameter present in game.

Steer force (cornering+grip)

 * FFB steer force input max="-11500.00000" // Recommended: 11500 (-11500 if controller pulls in the wrong direction).

This parameter should be changed only if wheel is pulling in the wrong direction. All Logitech wheels have a negative value


 * FFB steer force output max="1.70000" // Maximum force output of steering force, recommendation 0.8 to 2.0

This is the maximum output allowed for steering force.


 * FFB steer force average weight="0.90000" // How much weight is given to new steering force calculations each frame (0.01 - 1.0). Lower values will smooth out the steering force, but will also add latency.

Every frame, steering force you can feel is an average of previous frame force and new calculated force using this weight.

0.01 means new force is 99% previous frame force and 1% newly calculated force.

0.90 means new force is 10% previous frame force and 90% newly calculated force.

Note that it is framerate dependant...this causes FFB to feel different between two computers with different speed!

In rFactor, this way of smoothing steer force was replaced by a framerate independant algorithm.

This is a very important parameter...a lower value will give you smoother FFB with some latency. For example, with 0.30, it will remove the annoying FFB spikes you can feel in GTR2 with Porsche without adding a noticeable latency!


 * FFB steer force exponent="0.75000" // Steering force output "sensitivity". Range 0.0 to infinity. 0.0 to 1.0 = higher sensitivity, greater than 1.0 = lower sensitivity.

This parameter changes the way FFB output is filtered (how the forces increase when you turn the wheel…slower or faster than linearly). Defines how the steering feels (loose or sharp) in the center.

Lower value will give you a sharp steering feeling but will introduce oscillations around center and you will lose details in forces.

Higher values will give you a loose steering in center, but more details in forces.


 * FFB steer update thresh="0.0001500000" // Amount of change required to update steer force/vibe (0.0 - 1.0). Lower values = steering force updated more frequently = lower frame rate.

FFB forces generated by the wheel are updated only if their value has changed more than this threshold.

To get the most accurate FFB, and if you have no framerate issues, this parameter can be set to 0


 * FFB steer force grip weight="0.90000" // Range 0.0 to 1.0, recommended: 0.4 to 0.9. How much weight is given to tire grip when calculating steering force.

This parameters changes the way cornering forces and grip are mixed together.

0.9 means steering force equal 90% grip and 10% cornering. This is a very important parameter. It seems that in Simbin games this parameter is massively exagerated to focus on grip level.

Unfortunately this exageration has a cost: when you lose grip you suddenly lose 90% of forces and it is quite difficult to recover during oversteer as you have only 10% of force to guess what to do.


 * FFB steer force grip factor="0.60000" // Range 0.0 to 1.0, recommended: 0.2 to 0.6. How much of a factor the front wheel grip is on the steering weight.

This parameter changes the weight of front and real tyres in the grip force.

0.6 means grip force is 60% front tyres grip and 40% rear tyres grip.

steering column friction and damper
Friction forces are resistive forces that depend on the forces applied on the wheel (even if the wheel is not turning). The stronger you push, the stronger it resist.

A high friction steering will be easy to turn in straight line or at low speed (in such condition tyres are easy to turn, you need to apply a moderate force to turn the wheel, and so friction resistive force will be moderate).

But in conditions like high speed and strong turns where tyres are more difficult to turn, resistive friction forces will become stronger (as you are pushing stronger on the wheel). Increasing friction is like removing lubricant.

Damper forces are resistive forces that depend on wheel speed...the faster you turn the wheel, the stronger it resist. Like turning something into a thick fluid. Increasing damper is like increasing fluid thickness.

In Simbin games, steering mechanism effect on feel (usually very important, can kill a good sim) is only simulated using these parameters.


 * FFB steer friction coefficient="0.10000" // Coefficient to use for steering friction. Range: -1.0 to 1.0

This parameters defines how strong the steering column friction is.

0.10 means that the steering friction makes the wheel 10% more difficult to turn than the steering force alone.

Higher value give the impression of an old, rusty, non-assisted steering mechanism.


 * FFB steer friction saturation="1.00000" // Saturation value to use for steering friction. Range: 0 - 1.0

This parameter defines the maximum value friction force can reach. (it has to be compared to FFB steer force output max)


 * FFB steer damper coefficient="0.10000" // Coefficient to use for steering damper. Range: -1.0 to 1.0

This parameters defines how strong the steering column damper is. This coefficient is somehow multiplied by wheel speed to give a resistive force.

Higher value give the impression of a heavier steering column that takes more time and effort to move.


 * FFB steer damper saturation="1.00000" // Saturation value to use for steering damper. Range: 0 - 1.0

This parameter defines the maximum value damper force can reach (it has to be compared to FFB steer force output max)

Tweaking FFB parameters
Here is a kind of “strategy” in 5 steps (+2 optional) you can apply to obtain whatever feeling you want from Simbin games force feedback. I only take care of most important parameters to make it shorter.

Start from a simple FFB setup
To keep the process under control, start from a simple FFB setup.

I start from this setup, no vibrations, no damper, no friction, no tyre grip, 1.0 gain, 1.0 exponent.

FFB Effects Level="1" FFB Gain="1.00000" FFB steer force exponent="1.00000" FFB steer force grip weight="0.00000" FFB steer force grip factor="1.00000" FFB steer friction coefficient="0.00000" FFB steer friction saturation="1.00000" FFB steer damper coefficient="0.00000" FFB steer damper saturation="1.00000"

Try it...what you feel is tyre load and cornering forces...of course, the wheel is too light in center, jerky, it moves a lot, but you can feel mass transfer information.

Introduce front wheels grip level
Increase parameter "FFB steer force grip weight". This is the weight of grip information in the forces you can feel. It makes the wheel lighter when you lose grip. Too low and you feel nothing, too high and it kills some info like mass transfer.

If you increase it reasonably, you feel the wheel slightly lighter when understeering. I try to increase it until the wheel becomes as light when I understeer (grip info) than when I oversteer (mass transfer info).

introduce rear wheels grip level. (Optional)
For the moment, grip information you added is 100% front grip. You feel oversteering through mass transfer. This is what happen in real steering and can be enough for wheels with sharp FFB like G25.

If you really want to add rear tyre grip information, you can change parameter "FFB steer force grip factor".

Currently the value is 1.0 It means the grip info added is 100% front grip. If for example you set it to 0.8 grip info becomes 80% front, 20% rear.

If you want a realistic setup, keep it 1.0. If you want more information, lower it.

adjust steering force smoothing to get rid of FFB spikes and feel better car mass.
Az „FFB kormányzati erősségi súlypontja” paraméterrel nyomatok.

Output for current frame = calculated steering force for currentFrame *coeff+(1.0-coeff)*Output for previous frame

It allows to get rid of FFB spikes occuring on tracks polygon limits but introduces latency.

This table shows, for different values of the "FFB steer force average weight" parameter, events which are filtered...this is also roughly equal to the latency introduced.

For example, when parameters value is 0.32, you will not feel anymore FFB spikes that last less than 2 frames. If your average framerate is 50 fps, it means you get rid of spikes lasting less than 2*1/50=0.04s

Note that this is framerate dependant (rFactor changed this algorithm to avoid this dependancy). It means that computers with a higher framerate filter less and less the spikes and have a jerky FFB.

Try to decrease this parameter until you are satisfied with FFB smoothness without being disturbed by latency. FFB overall strength will decrease when filtered but this will be corrected later.

With an average framerate of 60 I use 0.28 to get rid of spikes without any annoying latency. This was very helpful with Power & Glory mod and it allows to have a smooth steering without damper, which is nice because damper may have a bad effect in critical manoeuvers.

adjust steer force output level to compensate for smoothing.
As you noticed, smoothing decreases the level of forces.

Increase slightly "FFB steer force output max" until it feels better...stay in reasonable limit (recommended range is 0.8-2.0)

introduce damper and friction. (Optional)
What you can feel now are forces coming directly from tyres and suspension geometry, reproduced without distorsion.

Steering multiplication mechanism (and power assistance) change dramatically how the steering feel.

They introduce smooth damper and friction forces you can feel all the time when you steer, and moderate tyre forces.

They make tyre forces more present close from center and less strong far from center to give a better feeling of the track.

If you want to simulate the direction column, set these two parameters:

FFB steer damper coefficient : defines how much dampered the steering is. 0.0 is unrealistic, 0.2 is reasonably dampered, 0.4 corresponds to a modern road car assisted direction, heavily dampered.

FFB steer friction coefficient : it should be negative, half the value of damper, to be sure that the wheel moves fast when required by the car movements. For example, if you like damper 0.2, friction between -0.1 and -0.2 gives nice results.

adjust wheel behavior in center.
To adjust wheel behavior in center and change steering sensitivity, change "FFB steer force exponent".

Lower value will give you a sharp steering feeling but will introduce oscillations around center like if a centering spring was used, and you will lose details in forces.

Higher values will give you a loose steering in center, but more details in forces.

Tip: to adjust this parameter, check wheel countersteering behavior...when you heavily oversteer and then the rear is brutally coming back and starts oversteering the other way....wheel should countersteer quickly.

Lower the parameter until you are satisfied with wheel countersteering behavior in such situation.

For information, default Simbin value is 0.75 and you should not go lower than 0.5 otherwise the wheel will oscillate violently around center.

It’s done. Now you can increase FFB Effects Level to turn on all vibrations.