Re: OT - Anyone tried this stuff

peter wrote:
Graham Hodgson <ttgmh@xxxxxxxxxxx> writes
peter wrote:
In 1988 I went on a Porsche driving day at Donington where one of the
activities was braking without ABS (those that had ABS had the fuse
removed to disable it.)
You drove at a steady speed (50 mph or similar) and when you passed a
marker cone you stood on the brakes and attempted to stop before running
down a line of pedestrians (more cones) placed at the absolute minimum
distance away for that particular speed.
Tiff Needell first demonstrated that it was possible and then gave us
quick instructions in emergency cadence braking...as I'm sure you know,
you jam on the brakes till they lock and then pump furiously till the
car stops. It is very counterintuitive, even though you know in advance
what you have to do, it goes against your natural instinct to push the
pedal as hard as possible and keep it there.
By the end of the hour most of our group had got within a metre or so of
the braking distance but that could have been due to the increased grip
of the massive amount of rubber we left on the track in our combined
efforts!

The rubber on the track would help, but what state were your tyres in?
50p shaped? How about the brakes themselves? And this is what I mean
about learning. A human can adapt brilliantly when well educated. If you
went 1 step further and had to swerve around an object 25m into braking
what would be the outcome?

AAMOF the second (no ABS) test of the morning was driving at a fixed speed towards some cones (representing a pedestrian stepping out into the road) braking at a marker cone, swerving to the right to avoid the "pedestrian" then swerving to the left to avoid a "box" of cones (representing a truck coming towards you) back onto your side of the road.
If you didn't get maximum cadence braking at every opportunity there was no way to complete the test without decimating the cones.
Many humiliating spins into the scenery followed.
There was also a timed slalom and an auto-test along with an evaluation by a race driver of your performance around the racetrack over a couple of laps.
Modesty prevents me from mentioning who got to take home the champagne for best score. <Huffs on nails and polishes them on shirt>

Heh, on my rally day there was no champagne to take home, but my nails were nicely shining...

This is the very real problem that auto engineers have with regards to
control systems. Giving authority levels to different systems, or
generating 1 large very complicated system. It's a tricky balance; the
systems have the potential to have a finer tuned control over the car -
but they don't *know* why the driver is doing what they are. They have
to try to recognise the problem from the braking/accelerator/steering
inputs. The human on the other hand knows *exactly* what they are trying
to do - they can see the problem. Their problem is one of knowing what
to do to get out of the problem.

Look at F1 drivers: Rubens is bemoaning the differences in the TC
software on the Honda to the Ferrari. He's trained his mind to expect
the TC to act in a certain manner, to assist at a certain time. With a
different system he's got to retrain his mind. From what I can tell he's
used to just booting it at the apex and letting the TC sort itself out,

Reminds me of a recent experience...with a history of driving hundreds of thousands of spin free miles in cars without traction control (mostly in cars renown for their ability to throw themselves backwards towards the scenery)...I'm driving my M3 in the wet up a slightly inclined dual carriageway curving very gently to the left. Accelerating hard at full throttle passing though 70 mph everything is fine, what can wrong? the road may be wet but I've got traction control! Then the road surface changes to what is obviously a less grippy surfaces, the back tyres light up and before you can say "oh ***" I'm going sideways and looking out my side window to see where I'm going!

It could have been a more grippy surface: The slip angle you had on the original surface might have generate 2000N laterally at the front, and then changing onto the higher grip it suddenly jumps to 2500N causing a spike in the yaw acceleration - back end comes around. I guess it depends on when the spin was initiated - front or rear wheels hitting the change in surface. If it was a slippier surface I'd have expected you felt a small amount of sliding at the front through the steering wheel, but that would have happened very quickly prior to the rears hitting the surface. Sounds more like a yaw control issue, and I'm not sure how clever BMW are on using TC for that (I think this is how TC gets used in F1 cars during corners).

You know that thing where folk say everything goes into slow motion, its true....I seemed to have enough time to wizz the steering wheel to full right lock to catch the first slide, then full left lock to catch the second tank slapping slide to the left...didn't manage to catch the third unfortunately but miraculously ended up neatly parallel parked about 6 inches from the curb facing the wrong way down the road.

Sounds vaguely familiar, except it was a 205 rather than an M3, and it was a roundabout rather than a bit of dual carriageway.

After all those years of "subconsciously" learning the limits of a car and keeping within those limits...I gave up the decision making to an electronic system and nearly paid a high price for it.

Worse still, on some systems a well trained driver such as you ends up confusing the system. Went to the dynamics open day at MIRA back in '99. They had one of their test drivers demonstrating a yaw control system on a 7 series down the wet straights. He turned it off, went down and performed an emergency lane change, having to skillfully catch the back end a few times before carrying on in a straight line. He turned it back on, performed the lane change and turned the steering as you expect many would - system worked great. Left it on, performed the lane change, tried to catch it like he did in the 1st case and we performed a graceful pirouette after a few tank slaps. Very enlightening. Obviously the system works great for most of the population who might panic somewhat and wheel the steering around, but those who know slightly better than to really wang the wheel around and think that they might have to catch it going the other way would be in trouble.

--
Graham

Make a little birdhouse in your soul...
.