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Old 20th April 2007, 20:23   #1
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Default Electronic brakes. Possible ?

I was wondering with so many advances in automotive technology, why is there no talk about Electronic brakes ? By electronic i mean brakes using electrical motors and wires instead of the conventional mechanical system consisting of rubber hoses and plastic tubes etc.

The clear advantages of this system that i can think right now:

1. It will obviously save a lot of assembly and use of plastic.
2. Instantaneous signal to the wheels.

Maybe some other advantages, which i can't think of right now.

But the question is, if we can have Electronic power steering (which again uses motors and wires instead of the conventional hydraulic system), what is stoppig the automotive world from not using Electronic brakes ?
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Old 20th April 2007, 20:30   #2
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There are already electronic braking - ABS, EBD etc. are all some kind of electronic braking.

However, in many countries there is a legal requirement that steering, braking etc. can't be entirely by wire.
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Old 20th April 2007, 20:37   #3
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What about electronic failures....

I don't mind electronics as a passive system (ABS, EBD). But I don't want to trust something as vital as brakes to chips and wires.
I think I'd feel much safer with a mechanical linkage.

Also in case of a failure of EPS, you can still steer.
In case of Electronic Brake failure, the wall, or a vehicle ahead stops you.

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Last edited by drifter : 20th April 2007 at 20:40.
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Old 20th April 2007, 20:55   #4
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See here the Seimens Electronic Wedge Brake

Siemens VDO’s Electronic Wedge Brake reduces braking distances by up to an average of 15 percent

Siemens VDO has tested a revolutionary braking technology under extreme conditions close to the Arctic Circle. The results show that with the Electronic Wedge Brake (EWB), braking distances on icy roads can be reduced by up to an average of 15 percent. The brake innovation will be ready to go into series production in 2010.
Siemens VDO - Braking Technology

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Old 20th April 2007, 21:04   #5
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One issue might be heat . Heat and electronics dont go hand in Hand. Another thing to consider is that Using an Elecrical/Electronic device for braking is really not that useful as by braking we are losing the momentum gained by the motion of the car and in principle we are wasting the energy . Thus the best use of electronics in Braking would be to gain the lost energy back. That is what the new generation cars (read as Hybrid) like prius does . It uses the energy dissapated by the braking forces to regenerate the batteries . The new versions of BMW's are also going to have some thing similar to recharge the electrical system. This enables the BMW to have an alternator system on Demand so the engine is not taxed having to run the alternator at all times.

ON a different note

If your idea of an elecrical brake was some thing like using the electrical energy to stop the car then it was utilised in a Speed record attempt to stop the car. The brake principle they used was an electromagnet which was designed to slowly retard the speed of the Car using alternate elctromagnetic pulses. It was in principle the other way of the Maglev (Bullet trains of Japan) .

I guess i might have veered off topic so i am going to stop. If you need more gyan on the maglev i think wikipedia has some good reading material
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Old 20th April 2007, 21:15   #6
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Actually Mercedes did introduce Drive-by-wire Electronic braking on the current E-class & last-gen S-Class but after repeated problems they were withdrawn & the cars reverted to/scheduled to revert to Hydraulic systems. Some of the problems were:

1. No linearity in braking, the pedal is like a switch either on or off, no middle position. This make smooth braking quite tricky & irritating.

2. There were reliability issues also & even though Mercedes had built in a backup Hydraulic system the customers were not happy.

The argument for using Drive-by-Wire in cars (ala Airplanes) has been going on for a while but certain rules in Europe make it hard. They have to ensure very high levels of reliability which with the current level of Electronics is proving hard. But rest assured some time in the near future you'll cars with systems like Steering & Brakes etc. being driven electronically.
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Old 20th April 2007, 21:24   #7
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Wasnt there some brake failiure in the SBC equipped mercs and that was just when an electronic module was used to apply the final brake pressure.
Cant even imagine how reliable electronic brakes will be(as of now).

Anyways Peugot was testing these items DCEITE mentioned some time back, But faced problems with ABS systems as the motors used to apply pad pressure weren't quick enough to respond to ABS's needs

PS: ur quick raghav

Last edited by Fuelled : 20th April 2007 at 21:25.
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Old 21st April 2007, 01:22   #8
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electronics can assist braking. but electricals can actually brake the vehicle (e.g. prius, returning the wasted energy to the battery).

another example is locomotives. they use regenerative braking. although they don't always return the energy to the system, rather waste as heat.
(they have dedicated cooling systems for that)

The reason they don't do mechanical braking is that at such high speeds and loads, mechanical brakes will simply break and fail. secondary and tertiary brakes are mechanical i guess.
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Old 21st April 2007, 14:24   #9
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I think what dceite was trying to get across was Brake-by-Wire, not regenerative braking, like in the locomotives or the electric / hybrid vehicles.

Looks like they're still perfecting the technology. And if Mercedes Benz does a recall, you know there's some way to go yet before we see it in our Marutis.
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Old 21st April 2007, 14:36   #10
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^^ Yup Elf is right. I was talking about Brake-by-wire.
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Old 21st April 2007, 15:43   #11
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the problem with by-wire systems is that when they fail its all fail. Zero or 1
When your hydraulic brakes fail(eg fluid leak or vacuum pump failure) you will see that the brakes get very hard. Sit on the pedal and chances are you will stop without a major mishap or something.
In electronics when such a by-wire system fails, its all zero.
Thats why Boeing etc., which have by wire systems have multiple fall back circuits, one fails, second one takes over.
Now a 737 is a multi million dollar machine, and therefore the tolerances etc., they work with are affordable, to make your M800 that reliable, your braking system alone will cost more than a few lakhs.
So mercedes etc., will be the first ones to see such systems, and lesser mortals will have to be content with topping up the brake fluid.

Other factor is, if its not broken, don't fix it.
If with ABS and EBD you can get good braking without unnecessary complications, why do it?
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Old 21st April 2007, 16:52   #12
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Is'nt Drive By Wire- encompassing all features like Brake,Accelration,Gear Shifts and all, Something like a super advanced cruise control..!
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Old 21st April 2007, 17:34   #13
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Quote:
Originally Posted by wolfinstein View Post
Is'nt Drive By Wire- encompassing all features like Brake,Accelration,Gear Shifts and all, Something like a super advanced cruise control..!
No, Drive-By-Wire is the name for the electronic control of any of those functions. This all encompassing concept was a Mercedes concept in their Vision 500 car which even has a joystick instead of a steering. They wanted to integrate the brakes, steering, throttle etc. on Drive-By-Wire.

Here are some pictures of that concept which was shown around '98 and was a sneak peek at the then about to be launched S-class (W220).







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Old 21st April 2007, 18:35   #14
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I don't see why the Brake-by-Wire technology, even with a secondary backup system should cost lakhs. I may be wrong, but it could simply be another wiring harness with duplicated sensors & switches.

Also, it doesn't have to be all or nothing. Not switches. Think potentiometers. And a servo could take care of pedal feedback, with the ABS system coming into play whenever the brakes are stomped on hard.

Methinks it's currently a more political issue than an execution & reliability issue, especially in Europe.
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