How much force on the steering column/how much feel?

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fiohaa
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Joined: 19 Apr 2012, 21:18

How much force on the steering column/how much feel?

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so i recently got to try the Caterham F1 simulator.
i was very surprised at the virtually non existent level of force feedback coming through the steering wheel:

- hardly any weight transfer feedback (i.e when in oversteer, wheel was very weak in pulling other way)
- Zero feedback through wheel for locked wheels under braking
- generally very light steering
- ridiculous snap oversteer - no feedback that the rear slipped, and when it did the car would do violent pirouettes at low speed
- they were using Rfactor Pro software

Just as a footnote, I was about half a second off Petrov, obviously have to take into account setup/fuel loads etc... but shows I was in the ballpark - and the only reason I was 'good' was due to playing sim racing games on the PC. I play rfactor and other driving simulation games, and rfactor has the worst of the tyre/physics/feedback models - it cannot cope with slip angles and the physics breaks down. The Caterham F1 simulator drove 100% exactly like a poor Rfactor F1 Mod....(hence why I was good in their sim because I was totally familiar with it!)

the engineers insisted that it was 1:1 with the real car, and based on measurements they'd made to find what steering forces were acting, and explained the lightness of the wheel and lack of feedback by saying that because the car is heavily aero dependent on grip and not mechanical (obviously true) but that this manifested itself in lighter than expected steering.

i dont believe them. yes ive never driven an actual f1 car, but just from common sense, from how the drivers react on tv, and from experience in some decent racing cars, i would expect the driver to be getting some good feedback through the steering wheel, and for the wheel to 'self right' in oversteer situations, as well as weighting at higher speed and some rolling resistance at low speed, and feedback if you were to lock front wheels.

the impression i got frankly was that the caterham engineers have clearly never driven a race car and seemed to be convinced that the data they'd put into their simulation models to give feedback through the wheel seemed to be accurate - to me it felt like a below average Rfactor mod (google it). And, as a footnote, they were indeed using Rfactor Pro.

im of course aware that info coming back to the driver isn't just through the wheel (g forces, through your bum, inner ear balance, visual) but the characteristics that i'd expect to come through the wheel itself were not present.

can anyone here comment on this?
what kind of varying forces would be going through the wheel?
does anyone have any technical knowledge on what kind of feedback the driver might be experiencing in terms of forces?

i just find it very hard to believe that what i experienced in the sim was 1:1 correlated with the car, as they insisted.
If it is 1:1, then F1 drivers aren't driving off feel at all, but visual cues and memory! (of course they aren't!)

silente
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Joined: 27 Nov 2010, 15:04
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Re: How much force on the steering column/how much feel?

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Typical numbers for forces trasmitted to the steering wheel by the tyres could vary much depending on steering geometry.

Another thing i am not well informed about is how formula 1 cars use power steering.

I have anyway a bit of experience in modeling vehicles (physics) in rFactor and i can tell you that, although it is not as good as other softwares, it could became very very good when the model is properly build. And in that cases, you feel the car very well and it´s normally "easy" to drive it (and you can recognise when it is starting to drift, when you lock a wheel, etc)

The big issue about "feeling" is that is not only dependant on the fact that Real car data acquisition = simulated car data acquisition. I had some experiences where the big picture correlation with a real car was very good but still the driver couldn´t "feel" the car when driving.

This depends a lot on tyre modeling of course, but also very much on the force feedback implementation and also on other car factors that initially you would probably not think to.

i write something and will deal again about that here, if you want to take a look :

http://drracing.wordpress.com/

Anyway, a think i know for sure is that, when you really build up a good model in a simulator (also rFactor), then also feeling should normally be quite good (at least on the steer).

Jersey Tom
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Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: How much force on the steering column/how much feel?

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F1 steer systems have considerable power assist, do they not? I wouldn't expect the steering to be overly heavy. Nor would I expect the steering to give you "oversteer" feedback. If you light up the rear wheels and break them free - why would you expect that to come through the front tire feedback?

In any case, rF Pro to my understanding is a good bit more modular than rFactor. You purchase it not so much as a turn-key solution as much as something where you can rip out say the damper model if it isn't good enough for you, put in your own. I would imagine many teams would take that approach with their own "guts" of the sim and just use rF Pro to wrap it all together and make use of the visualization engine. Point being, I wouldn't write it off as being as poor as rF not knowing what the customizations are.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

krisfx
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Joined: 04 Jan 2012, 23:07

Re: How much force on the steering column/how much feel?

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Surely if it was that bad the drivers would say "This isn't anything like the car"

You're never going to get 100% realism with a simulator, because as you explained there's no "feel"

There will always be a big difference between the real thing and the sim.

autogyro
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Joined: 04 Oct 2009, 15:03

Re: How much force on the steering column/how much feel?

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krisfx wrote:Surely if it was that bad the drivers would say "This isn't anything like the car"

You're never going to get 100% realism with a simulator, because as you explained there's no "feel"

There will always be a big difference between the real thing and the sim.
What point is there then?
Just acurately simulate a 250F Maserati and watch all of then spin off.

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turbof1
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Joined: 19 Jul 2012, 21:36
Location: MountDoom CFD Matrix

Re: How much force on the steering column/how much feel?

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If I remember correctly, during 2010 testing caterham, back then cosworth lotus, had no power steering. Their testdriver had to drive that car in the wet. He said that it was enormously exhausting to drive the car without steering assistance, claiming he would not have been able to run full race distance.

Also, Trulli claimed that his power steering was never properly, complaining about it for 2 seasons. Strangely though, Kovelainen never did.

Tells me 2 things if we throw the above info (which truly was an enjoyment to read btw): that caterham has very bad and weak feedback between the simulator and on track data, and that power steering itself takes quite a bit away from the feeling.
#AeroFrodo

autogyro
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Joined: 04 Oct 2009, 15:03

Re: How much force on the steering column/how much feel?

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It isnt just the power steering it is the high levels of downforce, which force the fitment of powerful power steering in the first place.
I should think it is very difficult to achieve any decent feedback from steering in the real car let alone positive self centering or meaningful data for a sim.
IMO the downforce rules cornering and the driver is just along for the ride in most cases.
Point and hope.

Greg Locock
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Joined: 30 Jun 2012, 00:48

Re: How much force on the steering column/how much feel?

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Unfortunately unless you know how much boost they use it is impossible for the average joe to decide whether it is a realistic effort level. I must admit the comment about mechanical vs aero grip does not fill me with confidence, perhaps they were having a lend, to be charitable.

Rule of thumb for a road car is that the assist varies between 0 on centre at any appreciable speed, to 10-20 times as much as the steering wheel adds, when parking. Typical values at typical speeds at 0.5g would be around 5. So very little of the effort needed to steer the road wheels in a corner is supplied by the driver.

Tommy Cookers
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Joined: 17 Feb 2012, 16:55

Re: How much force on the steering column/how much feel?

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Greg Locock wrote: Rule of thumb for a road car is that the assist varies between 0 on centre at any appreciable speed, to 10-20 times as much as the steering wheel adds, when parking. Typical values at typical speeds at 0.5g would be around 5. So very little of the effort needed to steer the road wheels in a corner is supplied by the driver.
interesting !

having done most of my driving before power steering I have long thought that it has its dangers
because it hides from the driver how much cornering force is being generated
(agreed fwd cornering has other tricks with manual steering)
powers biggest job is to hide from the driver the effects of 100-300 hp going to the steered wheels
another is to hide the scrub related disproportionately to tyre width
(steering was light in European-sized cars when tyres were less wide)
is steering load/'g' a formal requirement now ? (as in aircraft certification for 60 years)

there must be a big difference between ideal steering geometry for manual steering (ie not designed for stationary use)
and geometry for power steering, this having a large scrub radius to allow steering movement with the vehicle stationary ?
(30-50 million manual steering cars must have been made with geometry dictated by commonality with power steering ?)

F1 doesn't do parking, and used manual steering with high DF and wider tyres than those current ?

comment please, GL !

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strad
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Joined: 02 Jan 2010, 01:57

Re: How much force on the steering column/how much feel?

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I'm thinking that an F1 car does not have variable power steering.
If that is true then you need power assist equal to the stiffest resistance encountered..That being high speed with tons of downforce on the front tires. Seems to me the power needed then would feel like way too much at slow speed.
hmmmm
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss

Greg Locock
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Joined: 30 Jun 2012, 00:48

Re: How much force on the steering column/how much feel?

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Tommy Cookers wrote:
powers biggest job is to hide from the driver the effects of 100-300 hp going to the steered wheels
another is to hide the scrub related disproportionately to tyre width
(steering was light in European-sized cars when tyres were less wide)
is steering load/'g' a formal requirement now ? (as in aircraft certification for 60 years)

there must be a big difference between ideal steering geometry for manual steering (ie not designed for stationary use)
and geometry for power steering, this having a large scrub radius to allow steering movement with the vehicle stationary ?
(30-50 million manual steering cars must have been made with geometry dictated by commonality with power steering ?)

F1 doesn't do parking, and used manual steering with high DF and wider tyres than those current ?
To be honest on the Falcon we went 100% PAS 23 years ago, it just didn't make sense to compromise the majority of cars sold for the sake of few people who didn't want PAS.

Every study we've ever done say that the people who buy cars are not interested in high steering efforts. So the trick is to retain feel while providing enormous assistance.

Modern cars tend to run very little scrub compared with cars in the sixties, where 100 mm was not unusual in the uSA, although of course the 2CV had 0mm. The advantage of large scrub is that if you don't have the brakes on the tire can roll as you turn the steering wheel. The disadvanatge is that the lazy person who foot brakes while parking is not going to be able to turn the steering wheel!

But - just because buyers prefer light steering doesn't mean it is the only solution. On the farm we had one tractor with PAS, everything else was manual steer. Same with trucks. Sure, you have to use your muscles, but it isn't impossible.

There's no legislative requirement for Nm/g, I'd be very much opposed to that. The 'optimum' curves are non linear and speed dependent and vehicle dependent.

Tommy Cookers
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Joined: 17 Feb 2012, 16:55

Re: How much force on the steering column/how much feel?

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thanks for that !

fiohaa
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Joined: 19 Apr 2012, 21:18

Re: How much force on the steering column/how much feel?

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http://www.youtube.com/watch?v=B41LTCxiTYk

this is what i expected from the caterham sim. Tons of kick back, heavy steering at speed.

This was absolutely NOTHING like the caterham system. NOTHING.
So looks like Red bull engineers clearly agree with what I would have expected.

maybe thats why Caterham aren't doing well, clueless engineers.

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