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Why FFB in Simulations Does Not Work – By Leo Bodnar

Why FFB in Simulations Does Not Work – By Leo Bodnar

Force Feedback guru Leo Bodnar has published a very interesting article on Google Docs, explaining while the Force Feedback simulation in current simulations using current wheels falls short of being realistic.

Leo is very much a man in the know, having designed both software and hardware Force Feedback solutions, including a popular plugin for rFactor.

In the article, Leo explains why the current FFB simulation can’t be solved by more powerful or more smooth wheels as the underlying approach how FFB is handled by the current hardware & software is fundamentally flawed.

It’s not all bad though as Leo does not just criticize but also points out a possible solution for improvement. If you´re into the topic of Force Feedback and sim racing physics, make sure to not miss out on his excellent article.

  • Gregory Evans

    I never considered the wheel to be an actual simulator itself. Although now that makes perfect sense.

  • Sponts

    Funny, I have been thinking about this myself. I agree with his mechanical ideas but software wise I don’t think it makes that huge of a difference. What sim wheels really need is what Leo sort of suggests – real car like hydraulic power steering with torsion bar and steering axle with each end simulating wheel movements/forces to a point and that’s the only thing that should be changed in software, option to allocate both front wheels to 2 motors separately.

  • Vapaaneuvos Johannes Rojola

    Thats it then. Does this now mean that everything we play is crap? And I just bought iRacing for one year 🙁

  • lovretta

    No, it doesn’t. Have you actually read and understood the article?

  • Hompe

    Cool to see you bought iracing Rojola 😉  lets meet up online someday

  • Vapaaneuvos Johannes Rojola

    Gotta get in touch with you! 🙂

  • Justin ForzaBarça D’Cruze

    SUPERB article.

  • Hompe

    Go to myRacing -> myRacers and you will have a friend request 😉

  • Noel Hibbard

    I must be missing something. Whouldn’t the wheel lose center with his proposed design?

    Also, when I enter a turn with a real car I turn the wheel how ever much I think I need to (mainly from memory) and then I feel the forces in the wheel to get a feel for how much traction I have and make small changes to maintane front grip. This artical makes it sound like you enter a turn thinking, “Oh boy this turn is going to take 10lbs of force to get around”. Then he goes even farther to say that if a car had a limp wheel you wouldn’t be able to drive it. Well there are actually cars with tons of power stearing almost to the point that all forces on the wheel are masked and guess what, they are still drivable because you can still feel the gforces on your body to know if you are maintaining grip. This is where simulaters fall short. Lack of gforces. This is why FFB is so important. This new force concept sounds promicing, I just don’t see how you are going to totally throw out the polling of raw wheel possision. 

    • DrR1pper

      How do you get the steering wheel to the desired position in a real car? By applying a force/torque to the steering wheel that changes the momentum state of the steering wheel such that it attains the designed position at the desired moment in time.

  • Noel Hibbard

    Ah… I think I get it now.. The sim tells the wheel what pos to be in. Hmm.. That sounds interesting!

  • John G. Hill

    I think it’s all a matter of fooling the brain. That’s how real life simulators work.  You pitch backwards and forwards and your brain thinks it’s braking and accelerating.  (This only works if you are in an enclosed environment, otherwise the brain detects it’s pitching forward and backwards)   The first time I played Race Pro, (after playing Forza for years) I was amazed how the game worked with my FFB wheel.  When the car hit bumps on the road, my wheel would jerk at just the right amount, fooling me that the wheel was going up and down in relation to the size of the bump, basically fooling my brain.  It may not have been perfect, but it was a huge improvement over what I had experienced before.  It will get better.  I have a Fanatec now, and will go iRacing any day now.

  • Noel Hibbard

    The problem with the motion cockpits is they can only simulate 1g. That isn’t bad for simulating a road car on street tires, but race cars go well over 1g.

  • svizzy

    from my point of view the best method is in the middle of both. but thats impossible to realize. in the real world imput and output works at exactly the same time. there isn’t one thing first and then the other it’s happening seamlessly together.

  • Marco Conti

    I bet my wife would love that.

  • Silly(c)One

    That’s not the issue with SimGForce style motion cockpits, which are based on the principles of proprioception (http://en.wikipedia.org/wiki/Proprioception).
    Actually, with a good wheel (Fanatec, Frex, StarForce 7000, etc) and a proprioception-based cockpit design, you can fool your brain pretty well, with the wheel FFB taking care of the front of the car while the actuators take care of the back of the car, especially in 3DOF designs.

    Take a look at http://www.x-simulator.de/forum/ for more information about motion cockpits from 2DOF to 6DOF.

  • Silly(c)One

    But I agree with Leo about how wrong is the FFB working… We just got used to that difference in behaviour between a real car and a sim wheel. In order to have a more “real” experience, one has to focus on immersion.
    Motion cockpits help a lot, as big screens, projectors, triple screen and 3D setups, and anything that gives one a closer feeling to a real car, like a button box, or a dashboard, a handbrake for the rally fans, hell, even a fan for the open-wheelers maniacs… Whatever helps your brain not to think about something to be more focused on the moment and forget the fact you’re actually in a simulation…

  • mykem

    While there’s some thruth and solution in the article, the opinion for most part seems rather dated.  If you look at the more recent sims and that I mean non-gMotor2 derived- iRacing, nKar, to some extent Live for Speed or even Gran Turismo 5, the FFB accounts for how the front tires behave.  I have to quote AeroMechanical (from NGR Forum) who gave a great explanation of how iRacing FFB feels (this pre-dates ver. 2.0):

    “The best way I can think to put it is that iRacing feels a little more ‘rubbery’ if that makes sense. Pneumatic trail or whatever. There is a certain amount of springy play in the steering wheel around the area where the tire wants to follow its self aligning force. It gives the impression better that what I’m doing is applying force to the wheel rather than simply turning it. It really is just an impression thing though.”

    Exactly what Leo’s plugin for rFactor tries to replicate (and although for most part it’s an improvement over rFactor’s default FFB and to some preferable over Real Feel, however, the inherent lmitation of gMotor2’s FFB still persists).  And while it is an impression rather than something more palpable, it is a step closer than where we were.

  • Niels Heusinkveld

    Fundamentally all sims (iracing, lfs, gmotor based) work with FFB wheels in the same way and when using realfeel or leoffb, there is just as little (or much) immitation done by the gmotor games as in all the other games!

  • Remco van Dijk

    I don’t think that FFB wheels need to be changed at all.

    Steering a car is simply making the tyres push the car sideways, or more accurately make the tyres exert a force onto the road surface. The road surface will push back (Newton’s Third Law), and the car will turn. In order to make the tyres exert a force onto the road, you will have to turn the wheels, and in order to turn the wheels you have to turn the steering wheel. Hence, there is a direct relation between steering wheel rotation and force exerted by the tyres.

    The tyres push against the road surface, the road pushes back, and through the suspension and steering rack this reaction force ends up in the steering wheel, as a counterforce to your steering. Hence, turning the wheel requires force, as Leo argues.

    This is what a race sim should do: continuously calculate the forces on tyres, suspension and steering rack, and feed the resulting force to the steering wheel giving the wheel resistance when you want to turn it. When you turn the wheel, these forces change, which needs to be calculated by the sim and then the new resulting resistance of the steering wheel needs to be fed to the steering wheel’s FFB system.
    Hence, depending on the position of the wheel the resistance of the wheel and with that the force needed to turn it will change. So IMHO it is perfectly fine to communicate position from the wheel to the sim and the sim communicating back the resistance of the wheel correspoinding to that position. I see no need to turn FFB wheels into force measuring devices.

    • Anonymous

      Just because most sim racers are used to force feedback wheels does not make it right or good. Hyper Stimulator has know for many many years that FFB is false and Leo’s article confirms this, that is why Hyper Stimulator has never made a FFB wheel. They are the best wheel around for real feel steering and brake and pedals – Just ask anyone who owns one their opinion or get feedback from the scores of real racing car drivers that use them. No force feedback but by far more realistic and responsive than any FFB wheel on the market. Go to http://www.hyperstimulator.com to see the product. 

  • Peter Munkholm

    I guess the target never was to make FFB realistic, since in a real car, much less is felt through the steering wheel. Adding layers of FFB to the wheel, that tries to signal what you would feel on your body cannot be easy.
    If the above is the case and intent behind the force emulation, then Mr. Bodnar’s approach is not representative for those simulations.
    Indeed for his approach to work and tell the driver as much about the state of his car, the driver would need to use a full motion simuklator platform.

  • Big Ron

    Don´t know, what sense this discussion make. As long as it feels good and supports to control the virtual car, it doesn´t matter if its physically correct or not.

    It worked quite well for years and now someone tries to convince us, that it doesn´t? Come on.

    That it isn´t as correct as a real car can be understood by an idiot. But that´s not what FFB is made for.

  • Ed Luna aka eddiespag

    Thank you Leo for this article contribution, and to your many other contributions that many of us sim racers use on the hardware front.

    I wonder what sim racing will look like ten years from now?  Software and hardware can go in so many directions from this point forward based on discoveries that are both scientifically based and calculated guesses and then interpreted into creations.  Some philosophies will involve a dedicated commitment to go into a said direction, and sometimes will also require a cooperation and leap of faith by both parties (soft & hardware developers) to make it a reality. 

    Many of you have posted respectfully good and intriguing points of view that I actually enjoyed reading…you know, ‘Chesterfield Armchair sitting, having a cup of favorite roasted/brewed coffee’ kind of stuff.  Stimulating kind of stuff. 

    Our sport of sim racing it seems to have some definite specific needs that real world driving/racing doesn’t require for sure.  Sim driving does require some slightly different cues and/or increased.  For example, sound.  I won’t get into these because some of you have already explained or know why, but the crux of it comes from the five senses.

    Oh, Mr. Bodnar… (as I slam on my sim brakes to the floor with not a trace of brake fade, and with total Gilles Villenueve wheel lock-up and white tire smoke!)  You did what!!?  “I have designed and built a number of FFB systems completely from scratch, 10 times stronger and faster then consumer ones, with lower intertia, lower friction, two orders of magnitude, and higher force control accuracy.  They can respond to force commands and send position data to PC up to 1,000 times a second.  Smooth and powerful…” (text slightly edited and condensed)  I do hope that all of this will not be abandoned, real world realism be damned!  So I would ask that you would please continue (or reconsider) working with Mr. Todd Cannnon at CST at put one of these masterpieces out.   If not, then please have that ‘cooperation and leap of faith’ collaboration with someone like Mr. Gjon Camaj/ISI to go in this new direction.  Years from now many of us will be forever grateful, like we are to that persistent Thomas guy…the light bulb fella.   🙂  

  • Noel Hibbard

    Exactly. In a real car you don’t get much feed back from the wheel. If you disable power stearing you get a little more feed back but it still isn’t something you use that much for gadging front grip. About the only time you can real feel a lightness in the front wheels is when you fully lock the front while trying to turn. What we really rely on in real life is in your butt and I don’t see that becoming afordable in sims anytime soon. At least not a system that is truely convencing.

    So FFB in sims is really an added feedback that isn’t real used that much in real life to compensate for the lack of other feedback you get in real life (gforce).

  • Brooke Derry

    Well thought out article!   A very interesting point about setpoint and feeding back from that based on pressures input to the controller.  It makes too much sense!!!

    Make this Leo!  You have the brains!

  • Silly(c)One

    You have much more feedback from the wheel of a real car than you think, mate…

    Try it sometimes, concentrating on your hands while driving in real life… Even with powersteering.

    On the PC, though, in DiRT2 for example, FFB was extremely well done as I could feel my front wheel loosing grip only through the wheel (that was before I built my 2DOF motion cockpit)

    Leo’s article is very nice, but also very theorical and utopist… It’s not so bad, Leo, relax 😉

  • Silly(c)One

    Also in real life, your butt is cushioned for comfort, loosing a lot of the feedback that we have in motion cockpit.
    In real life, as you said, it’s the Gforce on your whole body that your brain interprets, and that’s how we trick the brain with the principles of proprioception.

  • Silly(c)One

    Immersion, immersion…

  • Hofstee

    If I understand correctly, he’s basically describing realfeel if it had more positional feedback.

    However when I drive with realfeel, it feels like driving on soap and I cant control the car anymore.

  • Bernard Richard Ubba

    Oh but it magically works with one of *his* products, doesn’t it.