Brake enhancer for emergency stopping

I am trying to find the best substance to spray on a tire to increase the static friction between the tire and the road, so a vehicle can stop faster in an emergency.
This is for a human controlled vehicle with a computer controlled collision advoidance system (including cameras, range finders, etc.).
The idea is to put a small canister of "spray" in the wheel-well of each braking wheel. When the computer detects that the vehicle cannot stop soon enough to avoid a collision, it will release the spray onto the tire, making the tire more "sticky" and decreasing the stopping distance.
I am thinking that a combination of some kind of grit and adhesive might work best, especially since it may be needed most when the road is wet or icy. But it should also help if the road is dry.
Some criteria:
1. The substance could either spray on the tire, or on the road directly in front of the tire.
2. Should be cheap. Experience has shown that people will pay a big premium for comfort, but not much for safety.
3. Should work on wet, icy or dry roads. It doesn't have to work perfectly, or in all conditions, but it must never make the situation worse.
4. Does not have to be reusable. It can be a "one shot" deal, and then you have to replace the canister.
5. Should not damage either the tire or the road. Since it will only be deployed in an emergency, some mild damage could be tolerated, but the vehicle should be able to drive away.
6. The substance could be ejected by a gas (freon/CO2) or by an explosive (like is used in airbags). Or it could not even be a spray, it could be an adhesive or grid embedded in a fabric, that deploys like a strip of tape that wraps around the tire.
This project is still in the brainstorming phase, so please let me know if you have any ideas of how best to do this.
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Bob wrote:

You should be asking this question in automotive fora, but I think the answer would be that there is no such substance.

An existing ABS system would be able to do the same thing--so far none has.

Good luck.

Forget the robotics--the search for that magic fluid would be a life's work in itself.
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--John
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I respect your idea but I think the best posible way to stop a car in the shortest distance possible with the best handling posible will be a mechanical solution instead of a chemical solution.
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snipped-for-privacy@gmail.com wrote:

Do you have any particular ideas in mind? I would like to hear them.
In modern vehicles the stopping power is limited by the friction in the tire-road interface. So any improvements fall into one of two categories:
1. Increase the tire-road friction 2. Something else
In the second category, I thought of a system that would fire a piton into the road surface, and then reel out a cable that would slow the vehicle. There are several disadvantages to this: It would damage the road surface (although much less than the damage to the vehicle if the collision was not avoided), and the deployed cable would be a safety hazard if not removed immediately. So the driver could not just detach from the cable and drive away.
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Bob wrote:

Drag chute, retrorocket, all kinds of ways to do this if your vehicle is at Bonneville with no other traffic for miles around. Now, consider your piton--the 18-wheeler behind you hits it, blows out a tire, control of the vehicle is lost, and instead of smashing the front end of your SUV on the Pinto in front of you you get clobbered from behind by 20 tons of liquid oxygen or whatever he's hauling.
You need to make up your mind--do you want to work on a robotic system or an alternative to convetional braking systems? They are different fields of expertise.
--
--John
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There are a couple of additional points to be made. I'm in agreement with much of what you write, and addressing my comments to the OP.
First, passenger car tires are not optimized for road gripping. Other factors, such as service life under non-optimal conditions -- road surface, temperature, inflation pressure -- take precedence. For example, most (but not all) DOT legal tires sacrifice dry road grip for all weather serviceability. IOW, they are designed to minimum traction requirements rather than maximum. At the other extreme, racing tires have fewer such limitations or aspirations. Even there, traction is finite. At any given finite grip level, it is possible to require more road gripping than is available, which is the fundamental problem to solve in racing. Inertia is an immutable (apparently) law of physics, and physics (or Newtonian kinematics at least) still apply.
Second, no amount of after-the-fact wishing will clear the anti-freeze or diesel oil from under your tires. Too fast for conditions is simply that: too fast for conditions. Until the anti-gravity/anti-inertia machine is ready for everyday use, you'll have to rely on something else. The only truly safe speed is zero; anything above that carries some foreseeable risk and thus requires mature assessment and mitigation.
Without squashing the well-intentioned thoughts, you need to get outside the box, to over-use that tired and tiresome phrase. The problem to be solved is not how to temporarily improve grip, but to obviate or at least minimize the need.
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Mike Young wrote:

Even zero requires mature assessment and mitigation. Park in the middle of an unlighted Interstate late night in heavy fog and turn your lights off and it won't be too long before something moving too fast for the conditions finds you.

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Yes, inertia is not your friend here. Alas, I haven't attained true masslessness yet. My thinking obviously remains rooted (!) in our Newtonian reality.
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Mike Young wrote:

Street tires have many differences from racing tires. Street tires trade absolute grip for a lot of warning. They make noise and start to slip (increasing slip angles for one) while still providing a large portion of their grip. This allows normal drivers to detect that they are pushing it, and back off. Racing tires maintain full grip as long as possible. Then they lose it all at once. Unless you are trained and experienced at this, and paying 100% attention, the sudden loss of grip at the end is startling.
The key is that this OP's fundamental idea is not very realistic.
--
Pat



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DRIVE SLOWER, the you wont need it

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"two bob" <4> wrote:

The phrase you are looking for is maintain proper control of the vehicle at all time.
--
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Bob wrote:

You've gotta think outside the box.
One word. Rockets.
Just imagine. Your cruising down the street at an unsafe speed, made unsafer still by the dark of night and an illegal amount of alcohol in your system. Then, without warning, little Susie jumps out from behind a parked car chasing her little red ball! "Who the hell plays with little red balls anymore?" you think as you slam on your breaks, but it's too late...or is it? Fortunately for little Susie, your safety conscious wife talked you into spending a little extra on the new Rocket Actuated Breaking In Emergencies System. Within milliseconds, a thousand pounds of thrust shoot forward from emergency rocket thrusters, previously concealed under your headlights, bringing your car to a screeching halt. You didn't flatten little Susie, it's a miracle! Of course, she now has burns over ninety-percent of her body, and the force from the blast gave you a concussion so bad you'll be a coma for the next 6 months, but hey, you're both still alive! Isn't technology wonderful? Just remember, you can't bake a cake without breaking a few eggs.
Now go, and invent the world into a safer tomorrow!
Chris
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Chris Spencer wrote:

Minor nit--that's less than half a g on most cars--conventional brakes can do better.

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... and thereby continue to fight the eternal, losing fight with inertia. My anti-gravity machine, once perfected, will obviate the need. You see, it is not gravity that is our enemy, but simple inertia. Once you learn to bend its will, to free yourself of its surly bonds, you'll find that wheels are not only unnecessary, but are entirely symbolic of a childish understanding of the world around us, inherited without challenge from our Neanderthal past. Reinvent the wheel? Let's do it one better. Do you remember George Jetson zipping around in his briefcase car and stopping on a dime? That day is coming.
Until its release, continue to exercise prescience, or at least commonsense. Operate machinery within their limitations. Inching limitations forward is an impermanent solution. Bending, or eliminating, them is forever.
Y'all think I'm a Crackpot, don't ya? You'll see. Now fast approaching Alpha testing...
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Mike Young wrote:

Lacking an antigravity machine, or at least control of inertia, there are other issues. For example, a rocket engine generating 80,000 pounds of thrust for .07 second will stop a 2000 pound vehicle moving 60 mph in 3 feet (all numbers approximate), killing all the occupants in the process.
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Sorry for the double-quote, but I somehow missed the original post. But just for the record, yes, I am absolutely positive you are a crackpot. I give you another year or two before you start blaming your failure to bypass the laws of physics on a government conspiracy to persecute you personally and cover up the alien flying saucers that would prove you right. Around the same time, you'll start CAPITALIZING your TEXT in random PLACES to add EMPHASIS and thereby demonstrate all the CLASSIC symptoms of the net.kook.
,------------------------------------------------------------------. | Joseph J. Strout Check out the Mac Web Directory: | | snipped-for-privacy@strout.net http://www.macwebdir.com | `------------------------------------------------------------------'
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J. Clarke wrote:

Can you recommend a particular forum?

Not true. If you throw sand on an icy road, you can stop faster. So clearly such a substance exists: sand. But I am looking for something that also works on non-icy roads.

I am not sure I understand what you mean. Are you saying that an ABS does not decrease stopping distance? That is a suprising assertion.
The system I am envisioning would work in addition to an ABS. Brakes work using friction between the brake pads and the drum or disk. But in modern vechicles that is not what is limiting stopping power. The limit is the friction between the tire and the road.

Well, it doesn't have to be a fluid. One idea I thought about was to deploy small spikes, like children's jacks, but smaller, so they would embed in the tire but not far enough to puncture it, and made of very rigid material, like tungsten-steel. As the tire rotates, they would poke into the road surface, and increase the friction. This would work better on softer road surfaces (such as asphalt) and less well on hard surfaces (concrete), but we have a lot more asphalt roads than concrete. The vehicle's computer should have information about the road surface, and could choose not to deploy under some conditions.
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Bob wrote:

Just look in all of them with "automobile", "car", "racing", etc in the title until you find one that is busy and seems to have people with technical knowledge.

If you throw sand on a non-icy road then you do _not_ stop faster. You are asking for an all purpose substance. If you find, patent it, and do even a half-assed job of marketing it you will become remarkably wealthy.

I am saying that if your magic substance existed an ABS system could decide when to apply it.

Yup.
This is how a studded snow tire works. They work very nicely on ice but they don't work as well as non-studded tires on dry pavement.

Doesn't work that way in the real world.

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On Sun, 20 Nov 2005 16:16:37 -0500, "J. Clarke"

Don't they put some kind of high-friction goo-stuff on those huge back tires and/or the road just in front of the tires on dragsters? (this is to insure greater acceleration rather than greater decelleration, but it's effectively the same thing) A possible problem with this might be a conflict with "should be cheap" as in drag racing they're always willing to spend substantial money to make the difference between winning and losing.

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they burn off a layer of rubber...
wrote:

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