Computers in cars....

[Gilly]

Back to the point in question, I have no ESP, no TC, no ABS and only mechanical power steering.

And I love it

I much prefer it being me and the machine. I suppose if I'm ever in a situation where TC or ABS would have saved me/my car I might feel differently.

Also, to cover the emergency stop/brake point, I've had to perform one once in over 4 years of driving when a young asian guy drove out of a side street doing ~25 or 30mph. He looked left and didn't bother looking right

Of course you can plan for such an eventuality, but on a 40mph road there are other more pressing things to worry about, like the traffic you can see and the stationary cars on either side of the road...

 

[The_Dark_Side]

Originally posted by Gilly
Back to the point in question, I have no ESP, no TC, no ABS and only mechanical power steering.

personally id rather have all the toys and have the option to switch them off depending on my mood.

 

[Simon]

Originally posted by The_Dark_Side
still none the wiser
ABS doesnt know what surface your driving r

I think this is the problem, it cannot use different modulation rates on different surfraces like it really needs.

Most ABS modulation systems will be setup for damp, clear tarmac.

 

[Gilly]

Originally posted by The_Dark_Side
personally id rather have all the toys and have the option to switch them off depending on my mood.

I wouldn't have been able to afford the clio with them. It was a different car with, or the Cup without.

I'd rather go without completely than not have the ability to switch them off...

 

[The_Dark_Side]

Originally posted by Simon
I think this is the problem, it cannot use different modulation rates on different surfraces like it really needs.

Most ABS modulation systems will be setup for damp, clear tarmac.

but surely it just applies full braking effort until it senses a wheel lock,then releases it.then as soon as the wheel starts to rotate again it tries once again to re-apply full braking effort.

the only difference driving on snow/ice would make would be this process would happen a lot faster+more frequently.

id still dispute that a human being could stop a non ABS car any quicker than the same vehicle WITH ABS.

i still understand an ABS systems job is to perform the same task as a human driver cadencing only a lot faster.

 

[The_Dark_Side]

Originally posted by Gilly
I wouldn't have been able to afford the clio with them. It was a different car with, or the Cup without.

I'd rather go without completely than not have the ability to switch them off...

thats questionable IMHO.

however there is the argument that the type of car you have may have its handling ruined by the extra weight involved.

 

[CaPtBlaCk]

Originally posted by Simon
I think this is the problem, it cannot use different modulation rates on different surfraces like it really needs.

Most ABS modulation systems will be setup for damp, clear tarmac.

So how is it setup?

The wheel is either locked or not. The idea behind ABS is to slow the road wheels without them actually locking. This is also equal to the amount of brake force applied at the pedal by the driver. Therefore the same loss of friction would be experienced by the driver of a non ABS equipped vehicle, so why would his reaction time and cadence braking be any more affective?

I think some of the theory went on the fact that on snow and gravel you want the wheel to actually lock. However this was used as a marketing ploy by Audi many years ago, I think they stated that at the time they were the only manufacture to offer an on/off switch for the ABS. Obviously such a good sound idea that the deleted it from the spec a few years later.

 

[Gilly]

Originally posted by The_Dark_Side
thats questionable IMHO.

Its completely irrefutable

 

[Simon]

Originally posted by The_Dark_Side
but surely it just applies full braking effort until it senses a wheel lock,then releases it.then as soon as the wheel starts to rotate again it tries once again to re-apply full braking effort.

This is its problem, if you stamp on the brakes you are asking for them to lock up as it is a shock to the system, when the abs comes back in it will again be like stamping on the brakes.

This is why you need different modulation rates for different surfaces in an ideal world. Its all control system stuff. You need modulation with a much more gentle reapplication of braking on surfaces with poorer grip.

 

[The_Dark_Side]

Originally posted by Gilly
Its completely irrefutable

if cost wouldve prevented you from buying your car then thats a fair point.
however all things being equal i just dont think the safety systems intrude on the driving experience noticeably.

 

[The_Dark_Side]

Originally posted by Simon
This is its problem, if you stamp on the brakes you are asking for them to lock up as it is a shock to the system, when the abs comes back in it will again be like stamping on the brakes.

This is why you need different modulation rates for different surfaces in an ideal world. Its all control system stuff. You need modulation with a much more gentle reapplication of braking on surfaces with poorer grip.

still not with you.
the system you describe with its more gradual reapplication of pressure may indeed stop the car quicker than current ABS systems.
however i still feel that either of these ABS systems would at worst stop as quickly as a human being without ABS

 

[moss]

This is quite an interesting test of ABS carried out a few years back

http://www.veta.se/abs66ice.htm

also read this...

From my physics course I seem to remember that maximum braking efficiency occurs just before the wheel stops rotating and then begins to skid or slide. I don't think a non-ABS car would stop sooner on a dry surface with the wheels locked and almost certainly an ABS car will stop better on contaminated surfaces unless the driver is very skilful.
J.A.P., Esher


Drivers are not skilful enough, they just believe they are. In the UK alone, more than 90 per cent of all accidents are caused by human error and it's a sad fact that current basic training standards aren't up to the job of ensuring safety on the road. You are correct in your understanding about when braking is at its most efficient - just prior to the wheels locking. Manually braking like this in an emergency, however, is one of the hardest things to learn. It is known as threshold braking, whereby a driver generates the maximum braking force just prior to wheel lock-up. The sensitivity and cool head required for this are expert-only qualities.
Most drivers faced with an emergency will simply stand on the brake pedal, which does two things in a non-ABS car. First it removes all steering control and second, on anything other than a dry, smooth surface, or freshly fallen snow, it increases the braking distance. By repeatedly stamping on the brake pedal (cadence braking), drivers can mimic the effect of ABS and retain steering control, but again this is a technique that requires expert tuition and much practice and it is never as efficient as ABS.

Best by far is a modern ABS system with electronic brake force distribution, which uses wheel sensors and a computer to measure how near to lock-up each wheel is. It then modulates the brake line hydraulic pressure around the point of lock-up, maintaining almost maximum stopping power to each wheel while retaining steering control. In a critical emergency, braking distance is often academic; it is the ability to steer round a hazard that can save the day, yet few drivers understand this or how to use their ABS brakes to enhance safety.

Being honest I have no real opinion on either side, Im just curious to which is proven to be better.

 

[The_Dark_Side]

Originally posted by moss
By repeatedly stamping on the brake pedal (cadence braking), drivers can mimic the effect of ABS and retain steering control, but again this is a technique that requires expert tuition and much practice and it is never as efficient as ABS.

my point exactly.
still havent seen anyone explain why they seem to think this is incorrect as yet.

 

[Bear]

Only have ABS and PAS on my car. I wouldnt go without PAS as its great for parking and there is plenty of feel in the steering not to be a problem. ABS I dont have a problem either, I regularly drive my car in a very spitirted manner and have yet to trigger the ABS in anger. The only time I have ever triggered the ABS was when I was driving down a steep hill and was braking to stop at a junction and the left wheel went over a man hole cover and obviously locked up on it.

 

[Jonnycoupe]

Originally posted by The_Dark_Side
still none the wiser
ABS doesnt know what surface your driving on.
if your wheel is still turning under braking then you're braking,if not the ABS system releases and tries again.
as for gradually,i was always lead to believe this happens in fractions of a second.

my understanding has always been that ABS does exactly the same as a driver cadencing does with 2 exceptions.
the ABS system becomes aware of a locked wheel infinitely quicker than a human driver could ever be,and it "pumps" the pedal faster than a driver can.

if the wheel locks up then i fail to see how a human driver can stop it either

The modulation threshold needed on snow for just enough brake pressure to slow but not lock the wheel simply isn't achiveable on most ABS control systems, down to ECU or speed sensor issues. So when the modualtion takes place the wheel will lock up again, unlike the road where you still get limited pressure to *** claiper to slow and not lock the wheel, the ABS again backs of the pressure in hope to regain grip and again TRYS to modulate the braking as to prevent wheel lock, it cant though as the pressure required to slow the wheels is simply too low on ice for the ABS.

This is happening to all four wheels usually and you hence end up with a 50:50 split of time with the car slowing due to locked wheels or rolling resistance on the snow. You better off locking up fully than spending 50% of the time locked and 50% simply rolling'. The feeling when you have no braking or locked wheels on wet leaves isnt nice, been there got the T shirt.

 

[Jonnycoupe]

Originally posted by The_Dark_Side
[B
id still dispute that a human being could stop a non ABS car any quicker than the same vehicle WITH ABS.

i still understand an ABS systems job is to perform the same task as a human driver cadencing only a lot faster. [/B]

Its all to do with design limits.

A ABS system will be setup such that the modulatioon applied isnt likely to lock the wheel again. So we have a situation where OEM want there cars to contol wheel lock-up even if the poorest low spec tyres have been fitted by the owner. Most car will have better spec tyres that this design spec, so the grip threshold limits have increased, there is now a margin that can be exploited to slow the car faster with higher modulation pressures and hence braking force at the wheels.

A driver with the remarkable human AI and knowledge processing will learn the limist of the car, and will be able to break to a point much closer to the threshold of the grip, a good driver will know how much he can brake before the wheel are likely to lock, whereas ABS test are simple foot to the floor jobs. If the wheel lockas at any point we are losing braking effciency. NOW IF the driver locks up he can candance brake, he will be modulating the pedal to exhibit much closer control to the tyre grip limits, where as the ABS will be applying 'Fortune Remould safe pressure'.

Hence ABS will take longer to stop in most sitautions with a good driver, its simple the benefit the ability to learn new stuff that makes the human excel. Can you imagine the differce now if you use high performance soft compund tyres

 

[Lashout_UK]

As far as I'm aware, ABS will not stop you faster in situations where there is no grip at the wheels, such as in snow - BUT - it will stop yourself killing you if you lock up the front wheels and plough into a wall, by releasing the brakes faster than you ever could - IF you could even get as far as taking your foot off the brakes when sliding.

I also agree with The_Dark_Side & Moss on their points about ABS simply being a hideously effective, automated method of Cadence braking.......

 

[Jonnycoupe]

I also agree with The_Dark_Side & Moss on their points about ABS simply being a hideously effective, automated method of Cadence braking....... [/B]

But on the flip side technical data and design limits mean that its only this for those of limited driving ability/car maintainace.. it good for them as they have no ability to candence brake using there own brains.

As 90% fall into this catergory then your right, its is effective. Particularly the ability to steer, whether most people possess the ability to steer in a crisis situation is debatble.

I didn't used to like ABS, I had experience it on a 2 Rovers. However im yet to get my Honda to lock up even in very wet conditions with low tyres, so its doesnt really fuss me too much that its there, as the control system it employs seems advanced enough to not hamper spirited driving.

 

[The_Dark_Side]

Originally posted by Jonnycoupe

very informative my friend...

so if i have this right,your saying almost all of the ABS systems in use at the moment "get it wrong" in certain situations right?

this means only a few prestige marques have systems that are more effective than a human driver responses can be.

this kinda answers flibsters original question.

if the above systems are beneficial to 90%(your figures) of drivers ,then we arent going to have many manufacturers willing to spend the daft amounts of money it takes to design a car for that market place.
if only 10% of drivers are capable of exploiting such a car,then an even smaller percentage of them again are likely to be able to afford it too.

point answered,thread closed.