Siemens VDO announces brake-by-wire system
Electronically-controlled mechanical brake systems developed by eStop, a company acquired by Siemens VDO Automotive
earlier this year, look poised to replace traditional hydraulic brake systems for many applications.
In this system, each wheel is independently controlled by an intelligent braking module, combining a 12-volt
electrically actuated "wedge brake" mechanical system and electronic sensors monitoring movement and force.
Eliminating the hydraulic system of pipes, brake cylinders, brake boosters and antilock control units lowers vehicle
weight, increases reliability, and reduces maintenance requirements. In addition, the system eliminates the need for a
separate parking brake. Overall, the system should open up some new packaging opportunities for the car designer.
Siemens expects the system to see production in this decade.
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Reader Comments (Page 1 of 1)
Motorin' 10:49PM (12/18/2005)
I was reading C&D's latest sport sedan article to see how the new Saab 9-3 with the turbo V6 fared. Oddly enough, note C&D's BMW 330i review.
http://www.caranddriver.com/article.asp?section_id=15&article_id=9993&page_number=10
"...Then the ABS lamp lit. We tried to execute one stop on our high-desert test road and nearly executed a 360 spin at 70 mph instead (thus, our braking number is from a previous test). Shortly thereafter several airbag-malfunction warnings lit up. Maybe it was just a coincidence..."
I just don't think the automotive world is quite ready for 100% electronic brakes or steering (yet?).
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the friendly grizzly 10:49PM (12/18/2005)
More dog-lick engineering from the Germans. No thanks. (And yes, I'd feel the name no matter what country this over-complex nonsense came from).
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Eric Bryant 10:49PM (12/18/2005)
As an electrical engineer, and as one who has dealt with one too many brake problems on older cars, I say "bring it on".
It's interesting that people will complain about brake-by-wire on cars, and yet have no problem hopping on an airplane. It's also interesting that a failure on a hydraulic brake system will be met with plenty of excuses, while a failure on any sort of electronic braking system is obviously just more proof that electronics suck and can't be trusted.
Auto IT, the "wedging" action of this system is little different than the servo action of drum brakes. While the system wouldn't work as well in reverse, it'd still work fine.
Andrew, feedback is a major problem with X-by-wire systems. I'll also be interested in seeing how they handle that problem. It'll likely involve an actuator on the brake pedal.
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Motorin' 10:49PM (12/18/2005)
"It's interesting that people will complain about brake-by-wire on cars, and yet have no problem hopping on an airplane."
Oh, I'm a nervous flyer too...the triple seven's all digital cockpit raises eyebrows. haha. Sadly, most people don't know much about a lot of the products they use either which is why they don't have a problem with things until something goes wrong. Still, I think the airplane manufacturers are slightly more thorough since they've got more experience with integrating high tech avionics into planes with a lot of federal/customer oversight. Plus, even they mess up designs every now and then too. The auto industry hasn't yet proven that they can get the simple electronics systems operating correctly.
My point isn't that electronics are evil...I'm a programmer and gadget freak extraoirdinaire. Of course, that also makes me privvy to how electronics can go wrong. Still, I'm just saying that I personally don't think the by-wire tech is suitable for cars yet, especially observing the problems car manufacturers are having with the more advanced electronic systems already in vehicles. Then there are the other haptic/feedback aspects as well.
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mickster 10:49PM (12/18/2005)
Acceleration by wire? Okay-if there is a failure, there's always neutral...but Brakes by Wire? Scares the living $*# out of me. And removing the mechanical parking brake? Now there's 0 backup if there's an electronics failure...and what about a false brake signal--this is not a good use of technology if you ask me!
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required 10:49PM (12/18/2005)
mickster, brakes by wire is no worse than having your hydraulic line burst, or lose the brake fluid, etc..
I am sure there will be safety features put in, so that if you lose one wheel's braking abilities, the other three will compensate (coupled with 4-channel ABS and wheel spin sensors, it should be able to keep the vehicle under control)..
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Justin Hollabaugh 10:49PM (12/18/2005)
It is natural to worry about changes to one of the most important safety system on the automobile. Plenty of people couldn't believe anyone would trust something like a hydraulic system when the the mechanical system of levers was pretty reliable. Hydraulics were once a new concept.
Fast forward to today and I see (and understand) the same types of fears. Fortunately the worst case scenario for a brake by wire failure is complete loss of electrical power to the braking system. In such a failure the brake system would return to it's default state, which would be brakes on (hence no seperate parking brake needed... turn off the car, brakes lock...).
Admittedly, cruising along at 70mph and having your brakes lock up is probably not going to be fun but when you think of electronic failures a sudden failure at highway speeds is probably even less likely than a hydraulic failure... which for all intents and purposes is on average: never.
My concern comes from a driving enthusiast stand point. Throttle by wire and brake by wire remove two feel inputs a driver has. This further isolation from the road may not fly well on small sports cars.
For the average vehicle though a sophisticated brake by wire system is likely to be far superior in terms of safety and performance than traditional hydraulic systems.
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Kianoosh 10:49PM (12/18/2005)
That's an amazing technology! I'm sure they've made the design fail safe to ensure in case of any failure system will be still safe to get the car off road.
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mickster 10:49PM (12/18/2005)
Hi required,
At least with brake fluid there are dual reserves such that if one half fails, you lose only 2 of 4 brakes.
Again to Justin's point, at 70MPH with an electrical loss, perhaps the idiot behind me won't recognize that I am massively braking (since there are no brake lights) and will rear end me or worse.
I also agree that this takes the control out of the enthusiasts hands, but so does ABS, Stability Controls, power steering, power brakes, etc.
Heck, I even worry about the patented Bose (yes the speaker company) electronic suspension...
I work in electronics manufacturing (major Japanese camera manufacturer) and I know that even the simplest systems can fail. Looking at the Toyota Prius-of which I am a big fan-and the problems it is already having with sudden stalling at speed-and I fear this system in the next decade. Add to it, Mercedes many electronics failures in the E & S (I know one guy who had his S600 suspension fail-due to electronics and it had to be flatbedded and he got a brand new replacement from Mercedes due to the damage and for the inconvenience); If Mercedes & Toyota are having such problems (and yes, I know Mercedes is in deep trouble on the quality front) what's going to happen to the average car with such technology?
Of course I just flew for the 6th or 7th time on a Boeing 777 to and from Tokyo, and fly on 757 and 767's all the time, as well as the hydraulically controlled and plagued 737, so I am already relying on Fly-by-wire and also so-called "proven" technology with failures...
Anyway, technology may be made to make things easier, but often it is much worse than what it replaces...
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Motorin' 10:49PM (12/18/2005)
Ever since Mercedes started hyping the brake-by-wire concept with steering by-wire, I've been a huge skeptic of both. Especially after having an electrical failure in my car earlier this year...on a rainy day...on the highway. This is important since my car has electrical power steering and also the cascading failure started a minute after one of the wheel sensors failed which initialy left me cruising with no ABS or stability control. Once the whole system went and I muscled/limped the car off the highway, the entire car was dead. If you tried to restart the car, you'd get nothing but flashing/twiching guages and displays...an epileptic nightmare. The total electrical failure was traced back to a bad ground, while I guess the wheel sensor helped kick the whole ordeal off. After that incident, I'm even more inclined to reject the brake by wire concept. Having no ABS, traction control, wipers, or power steering on a rainy day was bad enough...I'm glad brakes weren't on that list too.
Not only that, I'm pretty sure Siemens makes the ECU for my vehicle's engine and boy does that engine management system suck monkey nuts. After tons of software revisions, the engine still doesn't run quite right under some circumstances.
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Motorin' 10:49PM (12/18/2005)
...oh, but I will also admit that I don't recall the drive-by-wire throttle system becoming erratic as the other systems were failing, but of course I pulled off of the highway and parked at a gas station VERY quickly. Still, the drive-by-wire throttle in my car isn't always very pleasant when the electrical system IS working. The engine response isn't always predictable, especially when just trying to tap the gas. I'm not totally sold on the by-wire revolution. I can easily understand how it's nice for packaging and space usage for designers, but I'm not sold on it from a safety standpoint when used for steering and brakes as the complete system rather than assistance. Losing throttle control isn't pleasant, but not as much of a problem.
I still get a little nervous when riding in my friend's E500 sometimes, but the calming factor is that it's a big Mercedes so crash survivability would be pretty good. haha
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Andrew 10:49PM (12/18/2005)
Not having ABS in my car, my view is a bit skewed, but my biggest concern would be loss of feedback. How are you supposed to be able to feel what the tires are doing when you apply braking, and how much force you're giving?
Also, what kind of lag times are going to be involved? You'll probably never need to have instant acceleration for safety, so throttle-by-wire isn't a major safety concern I suppose, but there are times where that fraction of a second can make a difference in impact force if you're panic braking.
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Auto IT 10:49PM (12/18/2005)
Follow the link and it says, "As the wheel turns the wedge effect is automatically intensified", which seems to mean that the spinning disc rotor "pulls" on the pad and thus the wedge, forcing it further into the gap and therefore increasing the braking force.
So, what happens when you start rolling backwards down a hill, and brake, and the rotation means the wedge effect is automatically de-intensified?
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Just give us an option 10:49PM (12/18/2005)
My 05' Envoy has throttle by wire, its a bit weird. Especially when your a real "driver" not just a person with a car :) I wish they would give an option (switch) which would make the throttle by wire linear. Same with all future "by wire" technology.
Im not that concerned with SUV's and sedans but when sports cars starts using these "by wire" stuff I really hope they give use a switch
For MOST people it does help, but it would be nice for an option for us "drivers"
A must for every modern car is a master "engine off" mechanical switch. JUST in case the Embedded Windows XP (or vista?) OS Blue Screens. LMAO
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