PSM - a techy question

[pikey]

Right, how does PSM work?

I know what it does (sort of), but HOW does it work? I'm looking for answers for these two questions:

1. detecting the slide/need for intervention. How? Gyroscopes? Smell in your pants?

2. bringing the car back on track. It seems to brake the individual wheels - how does it actually do this? I mean for me to brake the car, I press a pedal which brakes all 4 wheels - so how can it do it for just 1 wheel?

Thanks

[BliarOut]

The factory manual describes the function perfectly. 56MB PDF download

The PSM equipped cars have a four channel hydraulic system with speed sensors on each wheel. There are rotation rate sensors, steering wheel sensors, lateral acceleration sensors and a booster pump... It's an impressive system.

Well worth the download

[JP.]

pikey said:

Right, how does PSM work? I know what it does (sort of), but HOW does it work? I'm looking for answers for these two questions: 1. detecting the slide/need for intervention. How? Gyroscopes? Smell in your pants? 2. bringing the car back on track. It seems to brake the individual wheels - how does it actually do this? I mean for me to brake the car, I press a pedal which brakes all 4 wheels - so how can it do it for just 1 wheel? Thanks

PSM uses sensors placed around the car to monitor the direction, speed, (yaw velocity speed of rotation around the vertical axis) and lateral acceleration of the car, it then calculates the actual direction of travel and applies braking to individual wheels if the car over or understeers beyond a set slip angle.

[pikey]

Wow!

.. and its such a small button!

That's pretty impressive! I have it kicking in often when playing and have wondered how it "just knows".

Its speed of operation is what gets me. Obviously not running on a Windows o/s then!

[maxxuk]

No, if it was running on windows, your car would often stop for no apparent reason, and then start back up again, equally for no apparent reason. And your PSM would probably put you in a ditch somewhere. DOH !!!