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 Post subject: Re: Cars cars cars
PostPosted: July 11 18, 5:03 pm 
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lukethedrifter wrote:
ABS isn’t gonna keep you from driving into the back of another car.

But there is technology now that actually will do that! Automatic emergency braking.


Last edited by Arthur Dent on July 11 18, 5:16 pm, edited 1 time in total.

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 Post subject: Re: Cars cars cars
PostPosted: July 11 18, 5:09 pm 
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Arthur Dent wrote:
lukethedrifter wrote:
ABS isn’t gonna keep you from driving into the back of another car.

But there is technology now that actually will do that now! Automatic emergency braking.


Almost bought a Subaru Forester that had it.


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 Post subject: Re: Cars cars cars
PostPosted: July 11 18, 8:53 pm 
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Arthur Dent wrote:
IMADreamer wrote:
Also of note, ABS actually makes you stop slightly longer than a well executed brake without ABS. Well that was true a few years back, maybe not with new systems as cars have made a massive jump in safety technology in the last 5 years or so.

Unless you are on a surface like gravel where locking up the wheels is actually the fastest stop, I don't think that's true. Or at least it's not for ordinary drivers. With ABS, a simple hard stomp on the brakes will get you minimum stopping distance or close to it. But the main point of it is to keep you in control -- the stopping distance impact is like 20% or something.



Your qualifier about ordinary driver may be what holds that together, but there is a reason most race cars do not have have ABS. If you think about the sheer physics behind it ABS is essentially turning the brakes on and off at a high rate, meaning that during the stop the brakes are not working all the time, or at least 100%. If you have a good driver with a feel for the car braking to the threshold of most effective braking will stop shorter than ABS.

A lot of weekend worry drivers who track a car will remove the ABS fuse or disable it via computer when they go to track days.


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 Post subject: Re: Cars cars cars
PostPosted: July 11 18, 9:22 pm 
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IMADreamer wrote:
Your qualifier about ordinary driver may be what holds that together, but there is a reason most race cars do not have have ABS. If you think about the sheer physics behind it ABS is essentially turning the brakes on and off at a high rate, meaning that during the stop the brakes are not working all the time, or at least 100%. If you have a good driver with a feel for the car braking to the threshold of most effective braking will stop shorter than ABS.

That kind of old timey logic is basically wrong. High speed speed precision independent control of each wheel brake gives massively more control than a human with a single pedal could possibly achieve. Turning the brakes on and off at a high rate is optimal because maximum control is not achieved by simply locking up the brakes with a lot of force. To stop fastest, you want to dynamically monitor the braking action at each wheel and apply the precise amount of force that slows rotation while keeping out of a skid. This will be a different amount of force at each wheel and each moment in time requiring high speed feedback control. The pulsing is a way to achieve that by modulating the average amount of pressure applied.

Dunno about the race rules in general but to the extent it’s not present, I think it’s mostly because it is banned for being too effective. The braking software put in consumer vehicles isn’t good for racing, but that implies race optimized software not human-only control.


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 Post subject: Re: Cars cars cars
PostPosted: July 12 18, 7:56 am 
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lukethedrifter wrote:
ABS isn’t gonna keep you from driving into the back of another car. You saw some nice gams, didn’t you?

LOL, no, not this time. There've probably been times that should've caused me to wreck but just got lucky.


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