Safe Speed Forums

sorry. this is wrong.

Active Cruise Control is a radar based extentions of Cruise Control.

There are systems in development that aim to do collision avoidance & collision mitigation but they are 10+years out (in my opinion) and fraught with legal complications.

Electronic Brake Assist is current technology already on many vehicles.

I haven't heard of any radar-based systems currently on the road. I understood they were all still under development.

Regardless of why the system got confused, the fact remains that the car took away my control and performed a potentially dangerous manouvre.

I think the radar based systems will be worse. If you need to steer around an obstacle then the last thing you want is a computer automatically applying the brakes and using up all your available grip.

Again, ABS should prevent this being a problem. I suspect the point of ABS is widely misunderstood, indeed I wouldn't have understood it myself if I hadn't happened to see a programme on TV where they explained it.

As I understand it, ABS is NOT intended to stop you in less distance, what it's designed to do is to allow you to continue to steer under full braking. In an emergency in an ABS equipped car, you should simply apply the maximum force you can to the brake pedal, allow the ABS to do its job, and steer to do the best you can to avoid, or reduce the severity of, the accident (this technique is known as "stomp and steer"). There are some situations where ABS will actually significantly increase your braking distance, e.g. loose gravel, and my car manual specifically advises that you should leave a greater distance from the car in front because of this.

Example link for further information:
http://autos.msn.com/advice/article.asp ... 01&src=GBT

Not so much that, the ABS takes care of that.
The biggest worry is if there's an obstacle moving into your path and you're at such a distance away from it that you will never be able to stop in time, so your only hope is to maintain your speed and steer around it - that way you'll be past it before it gets into your path. But, if the system applies emergency brakes you'll take longer to intersect the path of the obstacle, allowing it more time to get into your path, so chances are that even though you've swerved out you'll still hit it.

Cheers
Peter

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I disagree with the comments that ABS will make everything OK.

On any given surface, the car has a fixed amount of grip. Grip is needed for braking and steering (and accelerating, but that's irrelevant here). If you are using some of your grip for braking (intentionally or otherwise) then you have less grip available for steering and cannot change direction as quickly.

I believe that in an emergency situation, the driver should use their judgement whether to try and steer around the obstacle or stop in front of it. ABS will allow you to steer and brake at the same time, but neither the steering nor the braking will be as effective as if you had done one or the other.

Oh yes. Applying ABS brakes during limit-of-grip cornering is very very strange. It feels like brake failure.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

And for a real "I want to crawl under the dashboard and pretend this isn't happening" feeling try using ABS on gravel!

Regarding the brake assist business, I suspect we're confusing two different systems here.

Current technology used by several manufacturers is to analyse the behaviour of the driver in order to decide whether they are in a big hurry to stop or not (ie how quickly they go for the brake pedal, how hard they press it, how white their knuckles go etc). If the system decides that they are attempting an emergency stop then it "tops up" the braking force being applied, up to the limit of traction as dictated by the ABS system.

As far as electronic aids go I think this is a fairly logical idea, and doesn't really compromise much. If the driver decides to let go of the brakes he can do etc.

But the next step is to use radar (or whatever) to detect objects in the path of the car and brake to avoid them. That's a whole new can of worms and I see very little benefit. It isn't going to react any quicker than an alert driver to (say) a car emerging from a sideroad as it can't begin to react until the hazard is already in it's path, whereas the driver will already have seen the other vehicle set off or fail to stop - either way he would be well ahead of the machine. Perhaps if you fall asleep on the motorway it will prevent you shunting the car in front, and defer the accident for a few seconds until you veer out of your carriageway and hit something harder.

I can't really see many workable scenarios where this sort of system would give any tangible benefit, and as mentioned above it could be a massive hindrance if it decided to brake in a situation where the correct reaction was to accelerate out of trouble.

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Ticketo ergo sum : I scam therefore I am!

Very interesting Paul, but I think I'd rather not explore that! Maybe it was an experiment on a closed circuit?

Best wishes all,
Dave.

Yes. It was.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

my apologies... i misread the opening snippet. now i see where the radar stuff is coming from.

i wasn't aware of the bosch system which appears to pulse the brakes (once presumeably) to alert the driver to an impending impact situation.

collision mitigation & collision avoidance is a long way out still (5-10yrs) and will take alot of time to become mainstream (10yrs).
i don't think radar alone is reliable enough, the system i've driven uses LIDAR and there's alot of clever video based stuff around too.

That explains it, I always wondered why other drivers braked so hard on seeing a speed camera...

I wouldn't object to a radar-based "collision alarm" (like the ones that ships have), as long as the actual braking was left down to me.

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“For every complex problem, there is a solution that is simple, neat, and wrong.” - H. L. Mencken

ACC in effect does this already.. it only has authority to demand a small amount of decel. (0.2ish?). most systems will bong at you when they know they're screwed.

Try hard braking on a snow covered surface in an ABS equiped car - any road in the midlands after a light snowfall - gritting cover is pathetic. Find a nice strieght bit with no possible hazards (including vehicles behind) and try an emergency stop....

That simple test will be enough to make you extend 2 seconds to at least 10.

JT is quite right. ABS on gravel, including newly surfaced roads, is virtually useless, as it is on virgin snow. I once almost put a brand new 735i off downhill in a forest at some speed. It was the first ABS car I had owned and I was at a Welsh Rally School giving some tuition on a course. I took my Beemer up onto the stage with a couple of the students. All very embarrasing, but at least I didn't actually go off. Got it very sideways by throwing it and changing down harshly then back on the power for huge sideways. The students thought I had intended to do it.
What you need with ABS is an 'off' switch.

And sufficient understanding of the way ABS interacts with different road surfaces to know when to use the off switch, and when to leave well alone...

...still, for those who DO know the differences, there's always the fuse box

Surely the best "active safety" is the driver themselves? I fear this sort of technology is dumbing down the art of driving. The best safety feature in the world is too look as far down the road as possible and to plan ahead. Couple that with good concentration and reactions and I believe you have got the worlds best safety system. Its also fully interchangable between cars and the best bit is its available now. Not in 5 years or 10 years but it every driver in the land should be capable and have it 'as standard'.

Too much reliance on technology and crash protection is making some drivers complacent.

Yes I generally agree very strongly with that. The only bit I'm doubtful about is where you say it is available now. I'm not sure we could get all drivers into that happy state immediately. I rather fear it would take some time, but I'm sure that's the way we should be trying to go, and without further delay.

Best wishes all,
Dave.

wheres the balance then??

ABS.. a trained driver can do better.
power steering? masks road inputs and feedback from the tyres... and it could fail.
ESP.. a good driver won;t get into that situation anyway
Brake booster ?
TC...

all strictly speaking are 'extra' to the function of vehicle + driver.

some of these are only considered the norm because they are known trusted technologies... and the ones that aren't wll become so over about 20years.

Yes it was perhaps a little hopeful in reality to expect everyone to be able to drive like that immediatly, but in theory at least, all drivers should have and be practicing what I said everyday. It should be the basics of driving, but of course I realise it would take time for some people to get upto that standard.



Good question, and I'm not sure of the answer. However, as with speed cameras are we not looking at 'unintended consequences' again? Taking ABS, the technology is great, but do you think perhaps that some drivers drive closer and faster in the knowledge that ABS will 'sort it out' if all goes belly up? In theory of course we should all be driving exactly the same as before, just with an added back-up of ABS. But don't you think that some people rely on this techology now, rather then it been an additional benefit?

New technology in itself is not a bad thing if its is merely an additional driver aid, but its the effect on the behavoir of drivers who have a lot of technology that concerns me.