How does ESP work?

[matthewm1965]

Can anyone explain how the ESP system works?
It does a marvellous job of keeping the back end in a straight line through the snow.
I have driven other cars with traction control, but they just cut the engine power when it senses wheel slip. I get the impression that the MB system is more sophisticated than this? Does it have clutches in the diff to lock or reduce drive?
It doesn’t prevent the back wheels from locking when the auto box changes down when driving on ice. It would be nice if I understood how it works.
Thanks
Matt

 

[television]

In the car around the rear seats there is a pendulum device, so if the car suddenly slews, then a signal is sent to the BAS braking system, where engine power may be reduced and the brakes applied to one or more of the wheels to bring the car back to where it was before the slew. The advantage of the system is that it does not need thinking time,,it happens instantly, and known as ESP

 

[S80]

So because it happens before you realise it, that's like it happenning in the future - hence the name

 

[edz649]

So because it happens before you realise it, that's like it happenning in the future - hence the name

Can it predict when we are going to get more snow??

 

[whitenemesis]

In addition to the yaw sensor Malcolm mentioned the car monitors the wheel revolutions, via the ABS and the steering angle, throttle position. The electronic stability programe then adjusts the engine power and applies brakeing to individual wheels to regain stability.

What it cannot do is change the laws of physics, there are limits!!

 

[matthewm1965]

In addition to the yaw sensor Malcolm mentioned the car monitors the wheel revolutions, via the ABS and the steering angle, throttle position. The electronic stability programe then adjusts the engine power and applies brakeing to individual wheels to regain stability.

What it cannot do is change the laws of physics, there are limits!!

I didn't realise it could apply the brake to individual wheels..... That is clever!

 

[television]

I didn't realise it could apply the brake to individual wheels..... That is clever!

If you look inside any ABS pump you will see the four electric solenoid valves,, one for each wheel. These can open or close with the signals from the various parts in this circuit on the car, in many ways it is an extension of ABS where the existing circuitry has been added to,, the first was BAS and fitted to car as from around 1996 and then ESP that became standard in 1999

 

[Lisa Jayne]

So what is the difference between ESP and ASR? Sorry if it is a dumb question but I am blonde :Oops:

 

[television]

So what is the difference between ESP and ASR? Sorry if it is a dumb question but I am blonde :Oops:

ESP is what we have talked about,, ASR is Acceleration Skid Control

Take a look here at all of the MB systems
http://www4.mercedes-benz.com/e/home/innovation/recentdevelopments/safety/fahrzeug/asr.htm

 

[bigasotonuk]

Hi,
Whilst we are talking about ESP, is there any way of "completely" turning it off, as it has been mentioned (on other forums) that the dash switch doesn,t completely disable the system, and when you have the car rolling road tested there is a mode that should be selected (selected by STAR computer maybe or selected within dash menu in later MB's)to get accurate readings on the rolling road.
Any one know the answer?

 

[whitenemesis]

Yes there is a "Dyno" mode that totally disables ESP. I just can't find the link.

I seem to remember that there is some issue with using it for normal driving, as in it will revert to "normal" if the car is driven (as opposed to tested on a rolling road).

 

[bigasotonuk]

Hi,
I seem to remember reading something like this before, but it was before I had my AMG and my C230K doesn,t have it so to be honest wasn,t that much interested at the time.
If you come across or recollect where you read this I would appreciate any info.

 

[television]

You could pull the ESP module out,,then it will be completely disabled

 

[whitenemesis]

Still searching for the Dyno mode but here's some background info

 

[bigasotonuk]

You could pull the ESP module out,,then it will be completely disabled

But wouldn,t this disable the ABS and BAS as well?

 

[Alex Crow]

In addition to the yaw sensor Malcolm mentioned the car monitors the wheel revolutions, via the ABS and the steering angle, throttle position. The electronic stability programe then adjusts the engine power and applies brakeing to individual wheels to regain stability.

What it cannot do is change the laws of physics, there are limits!!

there is one more sensor, the lateral acceleration sensor. and yes, esp is a very effective and useful system - and as big a leap forward as abs was in my opinion. if anyone cares to test their esp they could try going ridiculously fast into a corner, putting full welly down exiting a roundabout or hooning around on a snowy carpark. they will find that when they crash, they do it facing forward

 

[matthewm1965]

Still searching for the Dyno mode but here's some background info

That's a good description of the system, just what I was looking for. Thanks.
According to that, it should prevent rear wheel lockup when decelerating on ice.
Arn't these cars good!!

 

[television]

But wouldn,t this disable the ABS and BAS as well?

It depends on the car some have 3 modules

 

[bigasotonuk]

Yes but surely each of these systems provide an input to the others, disable one you disable the other two, or am i misunderstanding something.

 

[whitenemesis]

In vehicles with engines 111, 112, 113, 605, 606, 611, 612, and ESP
the BAS function is integrated in the ESP control module
In models 163, 168, 203, 209, 215, 220 the BAS function is integrated in the ESP control module.

ASR is also integrated into the ESP control module