Creating steering that feels alive
Creating steering that feels alive
(OP)
Cars such as the original Lotus Elan, the Ferrari F40, the early non-assisted NSX come to mind when I think steering feedback. The sort of feedback that has the steering wheel wrigling and writhing with nuances of info from the tires and road. The more I look into the subject the more it's made to seem like a black art to come up with that sort of steering feel. Just copy another car that has characteristics you like and hope for the best.
I have looked at alignment specs and such but you can't really draw conclusions soley on that. I understand the effects that pneumatic trail and the various offsets in the steering axis has in a static case, however are there other aspects to this sort of feel that are dynamic? Say from shocks transfering loads around (since no road is perfectly smooth) and changing the steered wheels P trail? Or maybe the force vector of the road against the tire acting around the steering axis varying direction slightly with oscillations of slip angle? Both of which can be connected so maybe a combination. Or maybe something else entirely?
I would just like to hear what some of those in the know have to say about it.
I have looked at alignment specs and such but you can't really draw conclusions soley on that. I understand the effects that pneumatic trail and the various offsets in the steering axis has in a static case, however are there other aspects to this sort of feel that are dynamic? Say from shocks transfering loads around (since no road is perfectly smooth) and changing the steered wheels P trail? Or maybe the force vector of the road against the tire acting around the steering axis varying direction slightly with oscillations of slip angle? Both of which can be connected so maybe a combination. Or maybe something else entirely?
I would just like to hear what some of those in the know have to say about it.





RE: Creating steering that feels alive
Now if you want "feed back" --- come take a spin in my Mini Cooper!
Rod
RE: Creating steering that feels alive
RE: Creating steering that feels alive
I should proof my posts, but I often forget.
Rod
RE: Creating steering that feels alive
But yeah, a large proportion is tires.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Creating steering that feels alive
RE: Creating steering that feels alive
RE: Creating steering that feels alive
Norm
RE: Creating steering that feels alive
OP- Yes tuning the steering feel and tire development go hand in hand.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Creating steering that feels alive
RE: Creating steering that feels alive
I'm inclined to think that BMW's system (epicyclic in the column) offers the best chance of good feel, yet I've been told that this is not borne out in practice.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Creating steering that feels alive
RE: Creating steering that feels alive
Engineering has always been my love, but it ended up being my second career...
RE: Creating steering that feels alive
RE: Creating steering that feels alive
There are several almost insurmountable obstacles to getting this done. BTW: Hurrah for the use of the term Haptics, because this science is the key to a feeling objective in vehicle control (and not just road vehicles).
First, it is determined that only a fraction of vehicle evaluators are skilled enough to sense a road feel candidate. This is not an issue of training, but a skill brought to the table by a person who developed the skill at an early age (usually before 12 years old). Like certain eye reaction skills, you have it or you don't. This layer is a problem in vehicle development if the managing director does not have it (or worse the marketting and financial side of the business doesn't as a group, too).
Secondly, A vehicle in the hands of a proper evaluator must have steering and body controls "Que"d for an exemplary bandwidth. This is often misconstrued by controls people because its absolute bandwidth, not relative bandwidth. This means that the DC coherence and gain (via cross correlation of 4 signals), must be just as adequate as the 12 Hz bound. Too often, friction and damping become sacrificed for cost and quality reasons: Either the vehicle is good at low mileage and deteriorates at high mileage, or the other way around.
Thirdly, The presence of "prime" roadway signal (certain traits of transient aligning moment) can not be understated. A "good" set of tires is not enough with perfect body and steering control components. There are very important traits of a "Great" road feel tire. These factors are multiplicative: Any one sacrificed trait lowers the performance. One can not be used to augment another. The use of steady state properties to produce a candidate development tire can send you down a less than optimal path (so to speak) for road feel.
Forthly, A road feel evaluator can be tested on laboratory machinery to ascertain their evaluation skill ability. Its a visual as well as a haptic (feeling) response. Thus, machinery to produce various levels of multiply correlated movement and touch sensations is already in existence. (One in particular is in Canada: its a desireability for flying, too, you know).
Fifth (I'll take a pint, thankyou), it should be expected that a high powered, high frequency steer controller can do better than manual steering because the compromises made to maneuver at all speeds are too degrading of good or great road feel vehicle systems. You need some wattage for this.
Sixth(ly?) It is too often found that race car teams with multiple drivers can not use identical chassis and tire setups because the drivers do not bring the same feeling skill levels to the track. This becomes maddenly obvious when using one car amongst several drivers during testing sessions.
Lastly, a good experiment to run requires a roadway paved with a graduated level of lateral coarsness and a driver whose vision is restricted to eliminate path visualization.
This recognizes the ability of most good track racers to read the roadway as it evolves during a race. The chassis and tires read it, the driver reacts to it.
Oops, one more: The current problem with roadway simulators for roadfeel simulation and study, is the unacceptable screen delay of the visual field generator. Sure, an average "displacement" control driver will says it seems real. A "feel" driver will tell you its not even close. Many simulators showing F1 skits are driven by novices who wouldn't recognize the difference between an F1 and a Buick anyways. They just take the creator's word for it that its a Ferrari. Some of us also know that the Buick is wrong, too.
That's my spewage for the week...
RE: Creating steering that feels alive
I don't quite see why somone who works on Playstation simulators for a motorsports degree is acclaimed as the expert on steering feel, perhaps TCAir could enlighten us rather than insult us?
But nice rant anyway. I'd add that we have to calibrate systems that can account for production variation. For instance, if you take 20 nominally identical torsion bar systems and measure the boost curves you quickly realise that while the general shape of the curve of boost force vs SWT is meaningful, any funny little humps and dips that you put in (especially for friction compensation) will not be meaningfully present in most of your production population. Now add in the changes in upstream and dowsntream friction between different cars, and as they age. etc
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Creating steering that feels alive
"Thirdly, The presence of "prime" roadway signal (certain traits of transient aligning moment) can not be understated. A "good" set of tires is not enough with perfect body and steering control components. There are very important traits of a "Great" road feel tire. These factors are multiplicative: Any one sacrificed trait lowers the performance. One can not be used to augment another. The use of steady state properties to produce a candidate development tire can send you down a less than optimal path (so to speak) for road feel. "
What are some of these "important traits" that make a great road feel tire?
RE: Creating steering that feels alive
I'll settle for a good explanation for why I can hardly keep the car in any arcade simulation on the road at any speed, but can go half a dozen autocross events in a row, of several runs each, without hitting a single cone. I know it's got something to do with "feel" and feedback.
Norm
RE: Creating steering that feels alive
My experience with racing car games is that the 'driver' and the 'car' exist in slightly but disconcertingly different time zones. When the 'driver' makes an input there is a significant time delay before that input is seen on the scree
All those electronic calculations don't occur instantaneously, adding up to a lag which is enough to make the 'car' difficult to drive when you first start learning the game (and you crash a lot). With practice you subconciously adapt to the inbuilt delay and get somewhat faster with more control.
However, when you get substantially 'better' at the game (so you think) and the precise timing of 'events' gets more and more critical to improving your 'lap time', I think the subconcious tries very hard to make the inputs and outputs meet in real time and you then start to go backwards. At this point you start crashing a lot, again.
This delay is IMO the reason why even very good racing simulations are ultimately unsatisfying...
RE: Creating steering that feels alive
The physics model, in even the most sophisticated simulators, is a heavily streamlined version of the real thing. Typically arcade style games use 3 dof (dof=machine state variables) and a whole bunch of fudge factors, while professional simulators use maybe 25 dof, and a lot of lookup tables. These approximations are necessary in order to get the thing to run in real time.
To get the sort of results that I work with my models have hundreds of dof, and elaborate tire models that still bear (in many respects) only the crudest resemblance to the real thing, and likewise our steering hydraulic model is a very linearised model, same for the shocks. From that model I can accurately predict steering feel and handling, up to about 0.4g, and handling up to the limit with a great deal of extra effort. The downside is that the model will only run at say 1% of real time speed, in batch mode, ie not wasting cpu running the graphics.
The other issue of course is that in a game you only get limited feedback. On the other hand racing drivers claim to get some benefit from them.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Creating steering that feels alive
I'm sure there's a lot in what you're saying, and I understand that the game physics model must needs be a rather crude over-simplification of the almost infinite complexity of reality.
The lack of any meaningful feel (with a simulator steering wheel, not a pad like the kids use, because I'm old...) or other non visual feedback whatsoever is of course not going to make things any easier, but I'm sure the game lag isn't a figment of my imagination.
My road car has more immediate response than any game I've yet played, and my race kart's reactions are indistinguishable (by me) from being instantaneous (game lag is very noticable once you realise it's there). My race kart is much easier to drive than any virtual reality car I've tried...
The game lag creates a negative feedback, i.e. 'driver' sees a 'car / track' problem, driver reacts to problem (taking X time), electronics process driver reaction (more time), driver reaction appears on screen by which time driver is overcorrecting with the overcorrection still to come down the pipeline.
The driver now has to correct the overcorrection, but can't really tell when the correction is sufficient because the extent of the problem is not evident at the time the correction must be made. The 'car' ends up in a virtual 'tank slapper' of ill timed corrections and often 'crashes'.
In my experience these games need to be played with some degree of accurate pre-emption, maybe not too disimilar to driving a ferociously powerful but laggy turbo car...? It can be overcome of course, my PB at the virtual Forza version of the Nordscliffe is 6'18", but I 'died' at least a hundred times to do that. In the real world I'd have only died once...
Sorry, getting way off topic.
RE: Creating steering that feels alive
Now, on the other hand, a few years ago I tried my had at one of the aircraft, flight simulator, combat games. My favorite "ride" was a Messerschmidt BF 109G...Racked up some 200+ "kills" in it and only got shot down a few times. That was fun for a while, but it became boring and with my new PC, all the "flight simulator gear" is not compatible. It was a great time waster.
Rod
RE: Creating steering that feels alive
For the record it was an in house built sim, and not a PlayStation game. I wish it was a PlayStation game, would have been a lot easier. This unit has been used to verify steering settings for cars on the road today, you might even be driving one. Where the slight for a motor sports degree came from I will never know. For the record, BSME, and I am in the Marine field now. EIT and currently studying under a PE.
Please think twice before you post an attacking message.
Engineering has always been my love, but it ended up being my second career...
RE: Creating steering that feels alive
cibachrome's response is very accurate. The only point of contention is the OEM's knowledge.
Every single point was a problem to overcome in the project. We did an SUV vs a sports car.
I think it would qualify as a Buick.
Engineering has always been my love, but it ended up being my second career...
RE: Creating steering that feels alive
Yeah, well thanks for that non-insult. Try again.
As to Playstation simulators, that's just industry slang. Any HiL system with a steering wheel gets called that. This is part of the abstract " In this paper, a real time steering simulator will be presented to emulate the behavior of automotive steering systems. The re-configurable steer- by-wire simulator allows for the emulation of steering systems..."
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.