Safe Speed Forums

Spinning off from the brake light thread...

We have on most modern cars, sensors on each wheel, throttle position (demand if you like) sensors, all sorts of other sensors. We also have actuators in all sorts of places - means to lift off brakes selectively, means to apply brakes selectively.. on some cars means to impart a steering force via the power steering network.. means to back off - or boost - engine power..

What could be spun off with either solely the addition of software or softweare plus very cheap hardware?

Example.. Once ABS became standard, the addition of just a single transistor and a small bit of software was enough to introduce a crude version of anti-wheelspin, simply by detecting differential rotational speed between driven and undriven wheels and kill the engine ignition until it recovered (miliseconds typically). Ok - not perfect - unburnt fuel etc etc (although these days it is done by sending a "back off" signal to injectors to overcome that problem).

Evolving from the brake light thread, we have detection of rate of change of speed through, eg, engine braking in excess of a predetermined threshold using the ABS sensors to activate the brakelights.

What else?

Tyre deflation warning. Thereby lies a tale.

I filed a patent application on exactly that (tyre delfation sensing by ABS processor software; looking at faster-than-wear changes in wheel speed differentials) some 20 years ago. I couldn't get any interest and never went on to file the full specification.

Now I believe that several manufacturers are actually doing it. Notably BMW on MINI.

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I think Jaguar have done it for a while too!

Other variations on that idea are limiting the car's speed when the temporary spare is fitted (different rolling circumference to the other three)

...and then there's the less than scrupulous manufacturer who, in the 'States, used it to tell that the rear wheels were turning and the front wheels were stationary and the bonnet was up. This lead the car to conclude that it was on a rolling road having its emissions checked so it switched to a "legal" fuel map for the duration of the test

Other than that, my current car alters the delay on the intermittent wipers depending on road speed and I believe some cars alter the radio volume the same way.

I'd like to see a system incorporating a big pressure vessel which meant that the air conditioning pump ran preferentially when the car was on over-run thereby adding a bit of engine braking and not using as much fuel. It would charge the pressure vessel and then this would be released as required. Obviously, on a long, constant-throttle run it would still need to run the aircon pump when the engine was driving the car but I think a useful saving could be made overall. I guess the biggets disadvantage would be the extra refrigerant needed - probably worse for the environment than the extra CO2 of driving the pump!

Hydractive equipped Citroens use various standard sensors (speed, throttle position) along with some extra ones to determine when to switch the suspension to sport mode.

What about automatically flash flash flashing main beam when front wheels are helplessly locked up and the car is careering forward?

using ABS sensors to tell when the front wheels lock?... radical
although of course with ABS you wouldnt be careening anyway.
many cars put the hazards on now.

the active steering systems can just be a software change (depending on steeering actuator used).

lane departure warning systems also make use of signals & actuators from a variety of systems already on the car.

multi stage airbags depending on type & severity of crash.

seatbelt pretensioners linked to ABS/ESP.

i _think_ most modern ABS / ESP systems will have mismatched wheel speed detection, especially important with space saving spares (ick).
i suspect the problem with using it for detecting a flat in the early days was how to indicate it to the driver, which is much easier and cheaper now given the level of integration on modern cars.
the US legislation recently introduced for tyre pressure monitoring are fairly demanding given the cost constraints in automotive, i'm not sure indirect detection is allowed either (?).

Using existing GPS technology and a mobile phone (in a hands-free cradle, of course) wonderful things could be achieved.

Upon detection that you have exceeded the speed limit by a marginal amount, a call would be placed to a government "Fast-track" (pun intentional) department, where friendly staff would perform all the paperwork for you.
You would merely need to supply your bank account details and driving license number, plus your own private pass-phrase (don't want anyone else to claim your fine & points, do we?).

No more speed cameras or talivans needed.


With the addition of some cheap equipment, it would also be possible to detect that a Mars bar or apple has been removed from the Home office approved in-car food container while only the driver seat sensor is "on".
Bingo, call placed, similar routine, perhaps with an extra question concerning the nature of the food consumed, for market reaearch purposes. The government can sell this information to interested parties.

Gosh, I'm feeling really inspired tonight!

(apologies to all for trivialising this excellent thread, I couldn't resist )

Quite a few cars do that but I think the hydractive Citroens went a stage further and had one anti-roll bar droplink replaced with a small hydraulic ram so that in "sport" mode, the anti-roll bar was automatically "stiffened" (by shortening or lengthening the drop link) to level the car up. Only thing is, that's not all that useful other than limiting body roll - it doesnae change the laws o' physics cap'n"!

Exactly. For sheer stasbility, you really can't beat a low C of G, decent aerodynamics and the four wheels as far apart as they can get. I guess that explains why I like big saloon cars to some extent.

Having had a conversation with a mini owning colleague last week (whose tyre pressure light had come on), we tried to figure out how it works. Once he'd got it sorted, the dealer explained that ABS sensing wheel speed differential is exactly how it works; BMW use it too.
The utterance you are looking for is DOH!

there's some good research been done on split roll control.
allowing you to effectively change the front/rear roll stiffness proportion and hence radically shift the handling balance at will.

Yes, it seems to be a common misconception that body roll causes weight transfer to the outside wheels whereas, in fact, it is almost ENTIRELY C of G height that does it and the roll is just an effect.

On 5th Gear last week thay had the new Lexus which can basically drive itself as it won't drive into anything in front and will stay in lane, wake up sleepy drivers etc etc. And I can't tell you how glad I am my old Golf hasn't got anything more sophisicated than an electronic ignition module the size of a fag packet.
As with so many of these great leaps forward they remove more and more responsibility from the driver, which isn't a great thing and how long before driving a car without such trinkets and baubles means you are more likely to be suspected of fault from the off because the other car had them?

Barkstar

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