Can Magnets Really Prevent Car Crashes? Debunking the Myth

[M_Navas]

I'm trying to imagine parallel parking with such magnets. It would be...exciting.

you just gun it and the other cars will automatically move out of your way :P

 

[cesiumfrog]

you just gun it and the other cars will automatically move out of your way :P

If they're that strong, you're going to have to start worrying about polarity, whether they flip over and attract crushingly. Go with external airbags.

I posted earlier

Might have missed the edit. Anyway, you do want to use doppler range+rate-finders to trigger the external airbag deployment. Not something that depends on being switched on (by a driver whose negligence and human-error is already in issue), and not something triggered solely by range (since unnecessary deployment is expensive: interior airbags already cost ~$2000ea to replace).

External airbags might be the opposite of SUVs: any potential safety improvement is shared with, rather than wholly at the expense of, the other party.

 

[M_Navas]

Nah you did not miss the edit, in the edit I just changed the terminology from CAR to INFILTRATING OBJECT because I realized you wouldn't have to use it for just cars

 

[M_Navas]

also, I am aware there would need to be more factors in the airbag and not just having an object in a sensor but I don't really feel like getting into that lol

and for the doppler it would need to be something relatively sensitive due to cars like the prius not making much sound at all when they drive

 

[GRB 080319B]

You want to invent regenerative collisions?

My question was whether or not it would be physically possible to design such a system; I have no aspirations to invent such a system.

Are we having so many accidents that you figure it's viable to extract energy from them?

My question was whether or not it would be physically possible to design such a system, not whether or not it would be a viable option.

 

[DaveC426913]

You know, I just thought of another giant flaw in the magnetic bumpers concept:

For every repulsive interaction, there is going to be an attractive interaction somewhere else.

Say you give all cars powerful N-poles on their front and rear bumpers. Great. All cars repel each other as long as they are oriented bumper-to-bumper.

But those magnets also have S-poles. One car approaching another from the side will actually be attracted, worsening side-impact accidents!

 

[Hurkyl]

Meh - it would just force you to maintain safe following distance. To be effecive, these magnets would only need to have a substantial effect at a distance of perhaps 5-10 feet.

I agree. The trouble is, several feet of your car, both in front and behind, are invisible. "Keeping a safe distance" becomes many times harder when you can't tell where your car ends.

Even at a paltry 20 MPH, the normal recommended safe distance is what... 60 feet, give or take a couple?

 

[bp_psy]

Are head on collisions that common? I think this would just make other kinds of collisions more probable, especially rear end collisions.

 

[DaveC426913]

I think this would just make other kinds of collisions more probable, especially rear end collisions.

What is "this", and why would it make collisions more common?

 

[Pythagorean]

You know, I just thought of another giant flaw in the magnetic bumpers concept:

For every repulsive interaction, there is going to be an attractive interaction somewhere else.

Say you give all cars powerful N-poles on their front and rear bumpers. Great. All cars repel each other as long as they are oriented bumper-to-bumper.

But those magnets also have S-poles. One car approaching another from the side will actually be attracted, worsening side-impact accidents!

But with a 3D car, you could probably just face all the N-poles out, even on the sides

 

[pallidin]

And the cost to equip ALL cars like this are what?

Also, don't forget that we would also have to replace the iron-pole parking meters, lest we are unduly attracted.
And, how much environmental ferrous waste material do you want to clean off your car bumper each day?

Just a bad idea.

 

[DaveC426913]

And the cost to equip ALL cars like this are what?

Also, don't forget that we would also have to replace the iron-pole parking meters, lest we are unduly attracted.
And, how much environmental ferrous waste material do you want to clean off your car bumper each day?

Just a bad idea.

With all those S-poles - each, powerful enough to deflect other cars at several feet distance - pointed inward, the car will tear itself apart!

 

[ax3111]

I like threads like this, where a sophomore high school student can actually understand what's happening.

What I think could happen is that the magnets can be off all the time when driving, but turn on when the relativistic velocity between the car and another car exceed a certain point. This would cause cars driving on the highway to not be bumping off of each other, and it would also cause cars to not attract each other.

 

[julz]

Bringing this thread up as I had a thought about this.

What if, instead of putting an electro-magnet in front of the car, we put one at the four sides of the car, and kept them off until another car gets too close.
The magnet that would be in the right direction would then be turned on, thus a collision
could happen from almost any direction.
It would be possible to calculate the other car's distance using, for example, a laser.

However, I still think that it might be an unecessary cost and that we'd better think
about computer-driven cars, controlled by a master server. But that's another subject ;)

 

[cesiumfrog]

What if, instead of putting an electro-magnet in front of the car, we put one at the four sides of the car, and kept them off until another car gets too close. [..] However, I still think that it might be an unecessary cost and that we'd better think about computer-driven cars, controlled by a master server. But that's another subject ;)

Even if that could work, it would require the other car to have the same system before it could ever prevent collisions. (External airbags don't have that disadvantage.)

The same goes with controlling cars by a master server: aside from having a single point of (total catastrophic) failure, it implies needing to convert every vehicle simultaneously (and still, how will the central system know whether a kid has run onto the road somewhere). Better to start converting cars bit by bit. Today they already have automatic collision-avoidance breaking, and some cars can automatically lock on to the speed limit (until the driver puts an overriding pressure on one of the pedals). A few not only have parking range-finders but completely automated parking (systems that take complete control of steering and forward/reverse speed with awareness in all directions). Add a system to automatically lock onto the center of the lane unless the driver exerts a little steering pressure to override it. Improve the collision-avoidance detection systems. Start connecting these systems together and to the GPS (at first just to more intelligently predict hazards, later to start automatically leading into traffic turns etc), and later add systems to attempt automatic communication with other vehicles (at first just for better hazard management, although this could also be useful for measuring and routing around traffic congestion, but this potentially permits the same crazy traffic negotiations as a centralised system). So at each stage the vehicles can coexist with human driven vehicles, but eventually will build up the statistics to show that minimising human driver involvement minimises road death tolls.. in time you'll find legislators promoting disallowing manual control on public roads. Then, when your car is no controlled by its occupants, you'll have it drop you off at the door and go park itself, and you'll start to lease it out to work as a taxi while-ever you're in one place for a few hours.. The transport paradigm can shift.

 

[pmcleod]

too bad for anyone with a pacemaker i guess...

 

[lortech]

Everyone,

I Always have had some what of a accurate prediction of future events but often, do not follow up on them. Now the magnet idea would not fly as one user had suggested.

One idea that WILL happen in the future is cars WILL be in constant communication with each other. Each car will know the precise location of the next car via GPS location and through the use of physics and trig formulas built into the car computers of the future, the cars will not collide with each other for example, at a intersection. First generation cars will send visual/audio reports to the driver of a impending crash at a intersection then, its up to the driver to avoid the accident. Next generation, will possibly pulse the brakes and then, apply the brakes to avoid accidents.

All this technology, if proven, will substantially reduce car accidents in the future as long as the rf signals are not jammed or compromised.

The technology to a curtain point, has been proven on US army tanks. The driver of one tank can put the tank into follow me mode, and the tank behind him will follow the lead tank on the same path and spacing.

 

[DaveC426913]

One idea that WILL happen in the future is cars WILL be in constant communication with each other. Each car will know the precise location of the next car via GPS location and through the use of physics and trig formulas built into the car computers of the future, the cars will not collide with each other for example, at a intersection.

True, but...

First generation cars will send visual/audio reports to the driver of a impending crash at a intersection then, its up to the driver to avoid the accident.

This will not happen. By the time a bona fide risk of collision is identified, it is far too late to warn the driver and expect them to do anything about it. Any collision prevention will have to be computer-controlled.

 

[Redbelly98]

too bad for anyone with a pacemaker i guess...

Or a credit card or ATM card. Okay, not as bad as for the pacemaker, but annoying nonetheless.

 

[brookehogan]

it would just repel the other car forward into another car causing a chain reaction of cars repelling each other...also, this would in no way save the passengers from sustaining damage, it might save the car but based on the laws of inertia the repulsion of the car would have the same effect on the passenger as an actual accident...


http://awesomeparents.com/blog

 

[xxChrisxx]

As nice as this discussion is. Why on Earth would we need magnets and GPS to do it?

The S class already has the basic tools to do the job anyway. Adaptive cruise control, Radar sensor and conventional brakes. If it tracks an obect on a collisions course with a relative speed above a certain amount, the brakes will be applied.

It also has a system that mean you slam on it alters the braking force for you on gentle braking, not so much you get rear ended but enough so you don't crash. In the event of 'panic braking' ABS and brake assist systems work to reduce any collision speed.

Not totally foolproof yet but better than magic magnets and expensive satellites.

 

[MikeCB]

Hi, new here.

So let's say a car and truck were on collision courses with these magnetic bumpers equipped, wouldn't the trucks bumper field be higher than the cars? If so i could imagine the car being repeled downward and into a flip, at which point the car would pulled towards the trucks bumper, because once the car goes into a flip it exposes its metal parts to the trucks bumper field.

Did that make any sense? If so, does it work (in theory)?

 

[Redbelly98]

Welcome to PF.

Hi, new here.

So let's say a car and truck were on collision courses with these magnetic bumpers equipped, wouldn't the trucks bumper field be higher than the cars?

Not necessarily. That would depend on the strength of the magnets, which could be made the same for both cars and trucks.

If so i could imagine the car being repeled downward and into a flip, at which point the car would pulled towards the trucks bumper, because once the car goes into a flip it exposes its metal parts to the trucks bumper field.

Did that make any sense? If so, does it work (in theory)?

It is possible, in theory, that the cars lighter mass would make it prone to doing this.

 

[DaveC426913]

wouldn't the trucks bumper field be higher than the cars?

Not necessarily. That would depend on the strength of the magnets, which could be made the same for both cars and trucks.

He means wouldn't it be physically higher, i.e. as measured from the ground .

i could imagine the car being repeled downward and into a flip, at which point the car would pulled towards the trucks bumper, because once the car goes into a flip it exposes its metal parts to the trucks bumper field.

You raise an excellent point that should have been obvious earlier. The two magnets interacting would only bring the car to a stop if they were properly aligned and the vehicles were constrained to narrow paths. In all other case the magnets will still repel each other, true, but in a highly unstable way, not unlike bouncing a ball on top of another ball. And the momentum will be preserved.

The most dramatic and common effect would be to put the car(s) into a spin and thus completely out-of-control.

And yes, magnets that powerful will strongly attract the metal in the car, meaning the cars will slam back together.


I was foolish to think this idea had some merit. Anyone who has played with a couple of magnets, trying to balance then and bounce them off each other will know that it is a useless feat. They will spin and collide.

 

[Redbelly98]

He means wouldn't it be physically higher, i.e. as measured from the ground.

Oh! Thanks for clearing that up

 

[odmart01]

This is clearly not going to work out

 

[Jayanco]

The car magnet idea might not work, but I'm new to this and you all have sure made my brain work. :)

 

[abhishek ghos]

some mechanism which can measure the speeds of incoming cars, send signals, pulls up breaks and activates some magnetic repulsion, saves the day for two cars onto each other but there are other objects which can be a problem.
but the idea is cool and should be used in the time to come...

 

[ElCuabnito]

What if we lay out a thin layering of magnets around the bottom portion of the car, said layer would have a positive charge. And the we could modify the magnets by connecting them to the cars power so that the strength of the magnetic would be directly affected by the speed and power exerted by the car. We could also attach small sensors on separate areas of the magnetic layering so that if scrap metal does get attached to a section, then the power to that area would go to 0 and the scrap metal would fall off.

 

[Drakkith]

What if we lay out a thin layering of magnets around the bottom portion of the car, said layer would have a positive charge. And the we could modify the magnets by connecting them to the cars power so that the strength of the magnetic would be directly affected by the speed and power exerted by the car. We could also attach small sensors on separate areas of the magnetic layering so that if scrap metal does get attached to a section, then the power to that area would go to 0 and the scrap metal would fall off.

I believe page 1 explains the why the basic idea simply isn't feasible. The rest of the thread kind of hammers it in.