ESP under full brake load

[freddie2020]

Evening,

How does ESP work under full brake load?

Say braking at full force, and then violently turning the wheel right, and the car over steers.

With no braking in this situation the left front will be applied, but if the brakes are already applied - will the system then reduce brakes on the front right to create the desired torque affect to bring the car straight?

[Krikkit]

Yes, however briefly.

[anonymous-user]

road tuned ESP uses a system called "pick low" to ensure stability is maintained above ultimate braking.

Therefore the system will REDUCE total brake force in order to restore stability. This is done for two primary reasons:

1) Frontal impacts are much safer in terms of likely occupant injury profile vs speed than side impacts, Maintain stability generally results in a frontal impact
2) Average drivers are not skilled or expirienced enough to be able to correctly maintain stability under panic / emergency conditions just via the handwheel


These factors mean that road based ABS does not return the absolute shortest possible stopping distance under asymmetric conditions

[freddie2020]

Thanks, was thinking about this whilst playing about in the snow last year on a country road, it was very fun and interesting to feel the ESP work, when you can observe it operate at a lower safer speed and in slippery conditions.

Coming back to the point you made about ABS, I had an accident with a van on the same road where I live. I was doing about 30 mph round a bend.

But, when I steered to avoid, the left wheel was on very slippery wet mud, and the right still on the tarmac. There was almost no braking effect and the car slid as if was on sheet ice.

Is this an example of the ESP choosing stability over ultimate brake force? Cause I think in this situation is actually dangerous. Car used was 09 Golf MK6 GT TDI

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:06

[stevieturbo]

ABS and similar systems on very slippy surfaces....simply do not cope well.

So not really a good scenario to base them on.

[Chris32345]

freddie2020 said:

Thanks, was thinking about this whilst playing about in the snow last year on a country road, it was very fun and interesting to feel the ESP work, when you can observe it operate at a lower safer speed and in slippery conditions.

Coming back to the point you made about ABS, I had an accident with a van on the same road where I live. I was doing about 30 mph round a bend.

But, when I steered to avoid, the left wheel was on very slippery wet mud, and the right still on the tarmac. There was almost no braking effect and the car slid as if was on sheet ice.

Is this an example of the ESP choosing stability over ultimate brake force? Cause I think in this situation is actually dangerous. Car used was 09 Golf MK6 GT TDI

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:06

Would you rather have the right side of the car brake sharply and he left keep going spinning the car out?

[PositronicRay]

Chris32345 said:

freddie2020 said:

Thanks, was thinking about this whilst playing about in the snow last year on a country road, it was very fun and interesting to feel the ESP work, when you can observe it operate at a lower safer speed and in slippery conditions.

Coming back to the point you made about ABS, I had an accident with a van on the same road where I live. I was doing about 30 mph round a bend.

But, when I steered to avoid, the left wheel was on very slippery wet mud, and the right still on the tarmac. There was almost no braking effect and the car slid as if was on sheet ice.

Is this an example of the ESP choosing stability over ultimate brake force? Cause I think in this situation is actually dangerous. Car used was 09 Golf MK6 GT TDI

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:05

Edited by freddie2020 on Sunday 5th January 22:06

Would you rather have the right side of the car brake sharply and he left keep going spinning the car out?

People forget ESP isn't a performance aid.

[RumbleOfThunder]

Max_Torque said:

road tuned ESP uses a system called "pick low" to ensure stability is maintained above ultimate braking.

Therefore the system will REDUCE total brake force in order to restore stability. This is done for two primary reasons:

1) Frontal impacts are much safer in terms of likely occupant injury profile vs speed than side impacts, Maintain stability generally results in a frontal impact
2) Average drivers are not skilled or expirienced enough to be able to correctly maintain stability under panic / emergency conditions just via the handwheel


These factors mean that road based ABS does not return the absolute shortest possible stopping distance under asymmetric conditions

Interesting, thanks.

[freddie2020]

Chris32345 said:

Would you rather have the right side of the car brake sharply and he left keep going spinning the car out?

Now having taken in account what Max_Torque explained it does make sense - thanks for your insight.

My car and the van scrapped along each others sides before stopping, if the right brake had applied full force, could have been a partial or full head on.

I think it was just the extreme, of how I was pressing hard AF on the brake pedal, knowing was good grip on the right, and was like skidding on ice.

I think Max was saying that the ESP / ABS assume no driver input. So a harsher brake on the right wheel, might stop faster but will require some opposite lock, not something all drivers might do, so the systems have to assume worst case situation.

If braking at high speeds with different friction on the front wheels, I can fully understand how the systems are set up to be beneficial.

[stevieturbo]

The systems are generally designed to try and keep a car under control. To not skid, to allow a driver to steer around something etc under most reasonably normal conditions.

Although in a real emergency. most drivers will undoubtedly panic, maybe not apply brakes in a manner where the systems can work effectively, nor have the presence of mind to try and steer around in that panic situation. That's just the reality

But as already said, where conditions are very slippy ( snow, ice etc ), often the systems fall below par in the first place. But then....most average drivers in those conditions anyway...arent going to offer much either. But ultimately if no grip, not a huge amount that can be done.