1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Like your FFB strong? Think again..

Discussion in 'Sim Racing Hardware' started by Niels_at_home, Jun 30, 2011.

  1. Niels_at_home

    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

    [​IMG]
    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
    [​IMG]

    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.
     
    • Like Like x 14
    • Beer Beer x 3
  2. Alex Ball

    Alex Ball
    Web Nerd

    I think you may be confusing Strong force feedback for Badly Setup force feedback. In a real car the forces on the wheel can be high, but I agree they don't pull from side to side on the straights etc.
     
  3. Niels_at_home

    Niels_at_home
    Reiza Studios

    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 highly 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 favorite 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 / Live For Speed / 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 in game FFB strength at 20% which is not uncommon at all. In this example, 20% strength matches the maximum occurring force feedback of the physics engine to the maximum feedback your wheel can put out.

    If you'd use 100% in game 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 sim racers 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.
     
    • Like Like x 1
  4. Andrew Bortz

    Andrew Bortz
    GoldenBortz

    Will give this a try, have been running as you said 100% for all 3 force feedback settings for F1 2010.I just hope this doesnt knock my performance in game :cool:Thx for the advice.
     
  5. Knut Omdal Tveito

    Knut Omdal Tveito
    Premium Member

    Thank you for sharing this Niels and great to see you around the forum. I've noticed this weird FFB when I accidentally reset the FFB settings to default (high) setting or running mods with high FFB force, now I know why:good: Another effect is that the FFB also becomes less smooth at high forces as you can feel the teeth engage (for wheels with gears at least).
     
  6. This is a great article and should be stickied somewhere in the forums. I've been running my steering wheel at what I imagine is far below optimum force, but I like it that way. I remember running all forces at 100 in F1 2010, when I started, and, while the steering wheel rocking left and right in the menu was an annoyance, I liked the feeling of a heavy and slightly erratic wheel. I don't know why. The steering wheel would literally move the whole table, it was crazy.
     
  7. Brilliant, Brilliant, Brilliant! Really clear and understandable explanation of FFB resolution and the clipping effect of running too high a FFB setting! Thank you Niels... Brilliant :) I will sticky this thread now :)
     
    • Agree Agree x 1
  8. Interesting read :thanks:

    netKar PRO has a built in display that shows FFB strength, and it shows if you get clipping, so that's quite helpful.

    Other than that, I haven't really noticed it in other games, mostly because I'm pretty clueless.
     
    • Like Like x 2
  9. Yeah i agree with this.
     
  10. Although I know that in a real car the drop off in steering force indicates an approach to optimum slip angle (tried it out first hand in my daily driver and a go kart) I'm skeptical if this can be said for simulations, at least from all the simbin games from which I have the most experience. From what I've felt you quickly get understeer when you push it like this in the sim and that is of course if you have things scaled right which I'm quite sure that I do. This makes sense because it's really the only "edge" you can feel. You can feel a real car through the wheel and through the seat, when you approach optimum slip angles and the steering force drops off these two inputs conflict at least for someone inexperienced. The dropoff in steering force is telling you you're running out of grip but the seat is telling you you're just getting started. When driving a sim you only feel the wheel. If I was designing the force feedback I would make it behave intuitively like what the feeling through the seat gives you in the real deal and in my experience this is how it is in the sim. Still, it's possible that it's not the force feedback model itself but the car models that provide this feel through suspension geometry. I realize that isn't really the focus of the article as clipping poses a much bigger problem, I just don't want people cranking on their wheels based on this and then wondering why they're in the gravel trap.
     
  11. I think you guys are missing the point here somewhat...... What he is saying, by setting your FFB to a high setting, you are lifting the ceiling of the outputs beyond the wheels effective working range. If you have an effective range from 1 to 10 and use all your range, I.E. 10 in the first 50% of the signal, the second 50% will be lost as the wheel cannot go above 10 but the software in effect is asking it to :) Its got nothing to actually do with what 'feels' correct, Neils is trying to help people get the most amount of feedback from the wheel, not replicate a 'true' feel of the car, thats just not possible imo
     
    • Like Like x 1
  12. Alex Ball

    Alex Ball
    Web Nerd

    Gotcha :)
     
  13. Niels_at_home

    Niels_at_home
    Reiza Studios

    Heya, I'm not entirely sure I know what you mean? Yes any racing car will have heavier steering than a G27 class wheel can give us. That is why I suggested in the post to match the maximum FFB that occurs in the physics engine to the maximum capable output of the wheel. This way changes in force feedback from corners and bumps will be in the range of what your wheel can reproduce, giving you the most feedback, sadly not at the absolute strength you'd feel them in a racing car.

    You can increase the subjective strength of the force feedback but you're always limited to the low maximum force from the G27 class wheel, so when you keep adding FFB strength, you get the clipping I described, which might fool the user into thinking its heavier, but its just as heavy, but reaches this heavy steering at much less wheel rotation, with a huge amount of fidelity lost.

    Oscillation is often something FFB wheels do in some cases, definitely much more when you run too strong settings. Sadly this is kind of impossible to get rid off..
     
  14. A Brilliantly written and bang on the money article, clear, concise and 100% correct advice. Great article...... Nuff Said :wink:
     
  15. Awesome, enjoyed reading that and Im now gonna go out and do a bit of trial and error. Love the way its wrote to be easily understood and the charts helped a lot.
     
    • Agree Agree x 1
  16. great article, thanks for making an otherwise fuzzy topic clear.
     
  17. I'm not better Now :)
     
  18. Hey, that was pretty good. I never really understood how the ffb settings work and now you've gotten me one step closer. I guess the next step would be to really pay attention to changing them in game.
     
  19. A brilliant, clear and helpful article. Thanks a lot... I'm off to try and optimise my FFB experience. :)
     
  20. Omer Said

    Omer Said
    Weresloth Staff Premium Member

    Fantastic article, really useful for me thanks!