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Ditch Drive-, Brake-, and Steer-by-Wire?

Posted March 11, 2010 7:27 AM

Toyota is actively recalling hundreds of thousands of vehicles and retrofitting or replacing floor mats, gas pedals, and brake assemblies. Jerry Flint, a longtime auto industry pundit, suggests that the problem might not be with the mechanical parts, but rather that software bugs are to blame for runaway acceleration and braking problems. He suggests going back to mechanical throttles and braking systems. Do you think he's right or is he off his rocker arm assembly?

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#1

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 9:37 AM

Well, the whole reason that throttle-by-wire was adopted was in response to government mandates for higher fuel economy.

What better way to curb the lead foot and conserve fuel than taking control of the throttle?

Taking control of the throttle, particularly during cruise phase optimizes performance based on road condition demand.

Going back to mechanical linkages would surely fix the software bugs, but I am not convinced that Mr. Flint has considered the ramifications of downgrading corporate fleet average economy dictated by government CAFE standards.

A better question to ask would be if the government would be willing to relax CAFE standards to accommodate safety?

The answer is clearly no and additionally, US Senators are basking in the limelight of grilling Toyota so that they can appear to be the champions of the people. "Never waste a crises", I believe were the words uttered by our leaders.

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#18
In reply to #1

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 3:38 PM

Well, the whole reason that throttle-by-wire was adopted was in response to government mandates for higher fuel economy.

That is just plain wrong. Decades ago, I consulted with Ford on training engineers for the oncoming marriage of electronics and mechanics. Like it or not, many systems that were purely mechanical decades ago are now electromechanical: brakes, traction control, stability control, suspension, engine control, transmission control, etc.

Throttle-by-wire is not there mainly for fuel economy, nor is fuel economy primarily dictated by government. (People buy Priuses not because they are told to buy them by the government.) Comparable (model-by-model, i.e., Corolla-Civic, Camry-Accord, etc) Hondas get the same fuel efficiency as Toyotas but use mechanical throttles.)

Long before the recent mandates, throttle-by-wire was implemented. Throttle-by-wire is there mainly for easier, less costly integration of traction control and stability control systems, (in both it is advantageous to be able to take over throttle control from the driver) and other car systems. These systems sell well in luxury cars on their own merits. Because of volume sales they are now so cheap that the manufacturers are not screaming about having to have stability control on all US cars by 2012.

Some other reasons for implementing throttle by wire:

  • Automatic throttle matching (including "blips") in manumatics for upshifts and downshifts is best accomplished with throttle-by-wire.
  • Likewise for seamless shifts in ordinary automatics.
  • Throttle response, especially just off idle, can be better tailored to driver preference with throttle-by-wire.
  • Hybrid system power transfers are more smoothly accomplished with throttle by wire.
  • 4-6-8 engine systems (which people buy because they are crazy because they see value in them, not because the government requires them to do so) are best implemented with throttle-by-wire.
  • Cruise control is cheaper to implement with throttle-by-wire.
  • As engine compartments become more jammed-packed, a smooth cable run is more difficult to achieve.

The slight subtleties that can be achieved by throttle-by-wire over direct control have negligible effect on fuel efficiency. The driver, if he asks for immediate full throttle must get it -- there is virtually no difference in throttle response for large magnitude changes -- and the vast majority of drivers could not tell you if their car is by-wire or by-cable. (The public would not accept things like electronically dictated "pulse and glide" techniques that can have a measurable effect on fuel economy.) The subtleties (like wonderfully smooth off idle response in a Lexus) have no measurable effect on fuel efficiency.

It's about cost, driver feel, integration, etc, etc. with fuel economy being very far down the list: compare by-wire with comparable by-cable cars and you will find no difference in fuel economy.

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#19
In reply to #18

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 9:12 PM

Your arguments are a little scattered, but let's stick to the point. The word "whole" was a little too general on my part. So, it's maybe not the whole reason, but for passenger cars the big driver for developing the technology was improving gas mileage and emissions. Early adaptations of ETC (Electronic Throttle Control) were implemented primarily for the ability to gain control of the intake air supply (something not possible for Engine Management Controllers previous to ETC).

The early versions were not as well received because they did (in a small way) annoy drivers by overriding some driver inputs. This led to refinements in the technology as we have today, which is pretty much invisible to the driver.

As the technology advanced, stability control, shifting, and other benefits were taken advantage of and further developed. Those systems worked hand in hand..

I still contend the kick start was a means to improve performance of the vehicle and meet tightening fuel economy and emission standards. Your argument was mostly that present advantages were the drivers and many of these functions followed the development of ETC.

That doesn't preclude leveraging other advantages along the way of development. That's a given.

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#20
In reply to #19

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/14/2010 4:58 AM

Your arguments are a little scattered, but let's stick to the point.

Sorry you had a hard time following along. The point of my post is that your statement "Well, the whole reason that throttle-by-wire was adopted was in response to government mandates for higher fuel economy." was, and is, flat wrong.

The reason I responded to your post was because there is already plenty of incorrect info circulating (because of the Toyota debacle) and adding more drivel does not help anyone.

The Wikipedia article on ETC is essentially correct:

  • ETC facilitates the integration of features such as cruise control, traction control, stability control, and precrash systems and others that require torque management, since the throttle can be moved irrespective of the position of the driver's accelerator pedal. ETC provides only a very limited benefit in areas such as air-fuel ratio control, exhaust emissions and fuel consumption reduction, working in concert with other technologies such as gasoline direct injection.

You can read through a couple editions of the Bosch Automotive Handbook, and see that your hypothesis is wrong. The 1993 edition (the third) was from the relatively early days of EMS (the Bosch nomenclature for ETC). In the introductory paragraph about the system, they mention only "performing such tasks as torque reduction for electronic traction control (ASR)". They go on in a later paragraph to say that "EMS can perform various functions to enhance driving safety, convenience and engine management. After several paragraphs describing the uses of EMS in safety, convenience and comfort, they make one final statement re engine management: "Development is being carried out to adapt EMS to effect other engine related improvements (e.g., for improved fuel consumption.)"

So clearly, as I said, it was safety, convience, and comfort that were the drivers. In 1993 uses for the very slight effects on emissions and even slighter effects on fuel economy (beyond those that can be met by conventional cruise control) were still in the future.

So you have the development cycle backwards.

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#22
In reply to #20

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/14/2010 10:37 AM

Maybe I do have it backwards, but I am not so sure...

ETC Development

Also, read the first sentence of this article:

ETC Development

You can just as easily find contradicting sources, too, so it is not so "clear".

However, just as saying that the 'whole reason' is technically incorrect, so is saying that 'flat out wrong' is incorrect. They are both too broad a statement.

As for traction control, early and even recent versions of traction and stability control relied on applying braking to individual wheels. This was done on cars without ETC. Porsche 911s are a good example of this. Traction and stability control was not dependent on ETC, although, the two systems are merging as the systems mature.

I kind of see the argument as being a little petty. I stated that the sole reason was economy, you stated that economy had nothing to do with it (i.e., flat out wrong). I contended that the 'whole reason' was a poor choice of words on my part. The truth seems to lie somewhere in the middle and in 100 years from now it won't even matter. :-)

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#23
In reply to #22

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/14/2010 5:27 PM

I kind of see the argument as being a little petty.

I'm glad you were able to admit that. My own arguments, however, are profound, insightful, and reality-based. No... seriously, I agree that the argument on both sides could be considered petty.

My reaction to your original post has more to do with politics and tone than specifics, perhaps. ABS, ETC, traction control, stability control, and rollover control were all developed outside of government control, and were offered first on luxury and luxury-sports cars (and re rollover control, a luxury crossover SUV, the Volvo XC90). Very large numbers of people gladly paid $1000 or more extra for ABS in the early days, and ABS soon became a high profit item, with development costs having quickly been spread out over a large number of vehicles. Only after stability control has shown itself to be cheap to implement has the legal requirement to implement it on all US cars in 2012 come about. That requirement is no more onerous than the existing CAFE standards have been, which have been both easy to meet and easy to game: The German companies just pay the fines, GM hypes flex fuel (which makes a 15 mpg SUV appear to be a 45 mpg vehicle). Simple.

So although one can theorize that more efficient cars will be less safe, and that therefore, the CAFE standards should be relaxed, in practice is is hard to make that case. When fuel economy peaked in the mid eighties, deaths did not skyrocket. Since the fleet fuel efficiency peak in the 80's, the ton-mpg efficiency has improved dramatically, from 24 to 45. But death rates have not skyrocketed in that period.

A very easy way for manufactures to improve fleet fuel economy is to sell fewer SUVs and trucks. That would have a beneficial effect on safety, because is it primarily in collisions of two different masses of vehicle that the smaller car loses. Deaths caused by SUVs and trucks smashing into normal-sized cars have gone up in proportion to the numbers of heavy vehicles on the roads, and full-sized pickups have driver death rates that are about the same as the smallest cars (which are more dangerous than mid-sized cars). Get the pickups and truck based SUVs off the roads and death rates would drop, and the fleet fuel efficiency would improve.

Reverting to mid eighties ratios (25% trucks) from today's (50% trucks) would improve both safety and fuel efficiency but, sadly, leave rednecks and sociopaths with less ability to bond with their perceived brethren.

Your original post seems to suggest that car makers were forced into using ETC, because of oppressive government control over an area in which you may think -- I'm jumping conclusions in all this -- should be free-market based. But economy and emission control over the last couple of decades have been very nearly "no brainers" for manufactures selling into the US market. In 2004,when the Camry had ETC and the Accord did not, the Accord was significantly more fuel efficient, by about 8%, a very large margin in this market. (4 cyl. Camry: 24 mpg combined; 4 cyl. Accord 26 mpg combined). It's only at the lunatic fringe of the market (Prius, Insight, etc) where anything new and potentially challenging has been done -- and neither the Prius nor Insight were built to improve CAFE numbers.

How's that for a rambling rant? You're right... this is shaving points pretty fine, and in 100 hours (let alone 100 years) this will not matter much.

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#24
In reply to #23

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/14/2010 7:51 PM

Part of my point was that government CAFE standards generated changes to vehicles to meet the tightening standards (both good and bad). Manufactures simply looked for the most economical pathway to get to market under those regulations.

I think the smog pump was a good example of the auto industry's reaction to standard changes.

ETC can be a win-win situation in this sense (unlike a smog pump). It can subtly control the throttle to maximize fuel consumption and it can improve shifting loads on the transmissions as well as open the door to more refined safety measures like stability control.

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#2

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 2:53 PM

I have to agree, the electronic controls are there to boost economy and reduce pollution. I have driven electronic controlled cars for two decades and had little problem and certainly no out of control accelerations. I do find the electronics in the rest of the car a bit much, such as stability control and antilock brakes. I believe people should just learn how to drive their cars properly.

What I can not understand though is why can't the driver just shift the car into neutral or switch of the key off to cut power to the engine. Certainly the electronics do not over ride these. All cars I have looked at has the power for the fuel pump and the power to the injectors directly interrupted by the key switch.

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#3
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Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 3:12 PM

"What I can not understand though is why can't the driver just shift the car into neutral or switch of the key off to cut power to the engine."

Doing that will be the last thing on almost everybody's mind when the situation unexpectedly happens. Never underestimate the power of adrenaline and how adversely it impacts cognitive thinking.

Also, bare in mind that the cases you hear about on the news are the spectacular ones. The rest are far less dramatic and some form of driver corrective action probably prevented the mishap from making the breaking news segment.

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#6
In reply to #3

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 11:41 PM

I for one, have had the sudden acceleration problem, in a 1974 f 100 pickup truck. due to previous owners wrenching, the acelerator cable was not properly attatched to the carb and block. When i stopped at a traffic light, the motor mount broke and the engine hopped forward a few inches, pulling on the accelerator cable, throwing thr throttle wide open. I stomped the brakes,hit park and killed the ignition key before i went 3 feet forward, back tires screaming. 302 v8 slightly hotrodded. People just can not drive these days. I could make millions, watching my mirror and hitting my brakes when i see people behind me driving and tailgating, looking the other way.

After being rear ended a few times, I got fed up with tailgaters in louisianna, and hung a 5 foot long 8 inch oak log off the back of my truck for a bumper, swinging back and forth, held on by some very strong arborist rope.

Had an 83 datsun diesel king cab, which basically came factory with no rear bumper. This was an improvement from factory, so i was allowed to use it without police complaint. and they wouldnt even drive behind my truck. I had fun with it, changing bumper stickers. "if you must tailgate me, please check seatbelt, insurance, and iq" "whats in your bumper, got oak,yet?" Glued a little tigger figure onto the log, "back off or bounce off" "if you dont get the picture, heres your sign" " ever see a car that hit a tree? want one" "fast and furious, meet slow and serious" I had fun with it. I am about to hang a log off my truck here, theyre getting on my nerves again. gotta check with state police first, but it should be ok.

anyway on the car problems now, i wonder how much the car owners current income and economic status increases the likelyhood of "sudden acceleration" or stopping problems. I bet broke toyota owners are now more likely to have problems than financially stable owners.

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#11
In reply to #3

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 9:43 AM

I had the same problem with a new Tempo. After we got the damaged fenders and grill fixed, my daughter had it happen to her. After we got the damaged fenders and grill fixed, we sold the !!!!!!! car. We never had the problem again. Neither one of us had any intention of shutting down the engine, since it also drives the steering pump, which at the time of the incidents, was the biggest concern, trying to avoid hitting what was in our path!

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#4

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 3:23 PM

I have always found it strange that engineers, and politicians, have all of these facts, figures,and numbers to justify that what they did is better and good. Yet the common person just has his pocket book math and personal experience of what works and what doesn't to determine what is better or worse. If his pocket book math says its costing him more he will always believe it over what any engineer or politicians math may say otherwise.

Just the same is true of his personal experiences. If they tell him that something is worse he too will take that it is worse and have no regards for what the engineers or politicians say about him being wrong for thinking that something new is not better than what it was in the past. There are countless engineers and politicians saying that all this safety and mileage related crap is better and more cost effective. Yet there are countless millions of average people who have reasons based on personal real life experiences and costs saying that not all of these marvels of technical engineering are worth it but are rather in many ways are steps backward in performance, cost, comfort, and general usefulness.

Much of the improved fuel mileage hype is seen as crap by far too many. Some cars did get better but countless others where already there a long time ago that have been forgotten or excluded in the numbers for some very convenient reasons. Too many of us average nobodies still do have or did have vehicles, some of them built over 30 years ago, that ran consistently as high of numbers with lower overall operating costs than what the new so called high efficiency vehicles of the last decade plus get in real life driving conditions.

I for one do not need a certified dynometer readings to know my old pickup had far more power and better fuel mileage than what my newer one has now. Don't get me wrong, I like my big Red Ford but I hate its lack of power and the far lower fuel mileage it gets in comparison despite being much more aerodynamic and efficient or significantly heavier than what it replaced. My pocket book and my experiences tell me its true and I still have no reasons to believe otherwise. I also do not need certified tests to know that my friends car gets the same average mileage as a new Prius in the same realistic driving conditions despite being late 1980's Chrysler tech. He grins, brags about it, and shows it off every chance he gets!

I hear engineers saying that cars are getting bigger. WTF? Really? Where are the Cadillac cruise ships of yester year? Or the land yacht Lincolns of days past? What about the battle ship sized Buick's we rode around in as kids? Where did all of the old Pontiac yard barges and oil rig sized Oldsmobile's go? How about those Ford wagons that could seat four fat guys in the front seats alone? And those bus like conversion vans that could carry a little league team along with three adults comfortably? Where did the stadium sized Chrysler Imperials and Chevy Impalas disappear too as well? Non of these got bigger, only the small imports did. The larger half of the vehicular sizing and improvement equations seem to always get left out for some convenient reason.

The full size cars of today would not even be considered the middle size class that was in effect when these American monsters of metal represented the normal sized family vehicles of the day. The biggest SUV's out there are still far short of the conversion vans that where around 20 years ago. The real sad part is most of those old monsters got about the same real life fuel economy as the new stuff that replaced them does now, and some where even better.

Vehicles got bigger and mileage got better my ass. They only got bigger if you don't include the biggest that where already here decades before and those had key switches that actually shut things off. Plus the gas petal was attached the actual throttle mechanism and all the brakes had direct physical connections from the driver to the wheels. They didn't need to hide crappy engineering and poor design behind computers and code systems back then. Engineers and politicians be dammed, too many of us paid for the fuel back then and kept track of those numbers and to this day still do. Our pocket books and experiences just tell us something is not right with what we have now and no engineer or politicians facts, figures, or charts will make us believe otherwise.

Some things did greatly improve over the years, just not things that they feel the need to keep telling us are improvements.

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#14
In reply to #4

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 10:41 AM

Tell it to my dad with his 9 mpg Chevy C20. I'll keep my 32 mpg Ranger thanks...

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#29
In reply to #4

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 12:17 PM

In the spirit of Point-Counterpoint, I'll offer this not to tcmtech, but to people who appreciate science and engineering.

Although tcmtech's thoughts may not be exactly mainstream , there are loads of people who share his disdain for science and engineering. Anti-science and pseudoscience are both on the rise.

I'm a member of SAE and have had Ford and Volvo as clients, but have never worked for Toyota. Nevertheless, like most automotive engineers, I acknowledge that Toyotas are, in general, extremely well-engineered. Did they screw up with their throttles? Only science and engineering can answer that, because only through science and engineering can you know whether their cars are significantly different than others. Having an appreciation for science and the application of statistics, I can say yes, they are different, and yes they screwed up. Toyotas lead the list for claims re unintended acceleration, with more than 4 times the number of claims of the next worst manufacturer. These claims have been coming in for several years, so it is unlikely that (before now) people are just "getting on the bandwagon" and over-sensitive to Toyotas vs the other brands, and therefore over-reporting incidents. Did Toyota distort the truth re throttle problems? It certainly appears so, because their claim that this is all new to them and a recent phenomena, is not true: the first NHTSA investigations were in 2002, I believe.

This has little to do with throttle-by-wire as a concept, however, because it has been used for over two decades now, and only Toyota is having problems. In general, the safety advantages associated with throttle-by-wire outweigh the potential disadvantages. There are no true brake-by-wire cars (in which there is no mechanical-hydraulic connection between foot and disc caliper) But if the OP is referring to ABS, traction control etc, in which the brakes can be applied automatically, then there is a clear and obvious advantage to these systems that has been demonstrated both statistically and by dramatic improvement in vehicle dynamics. (The insurance companies who give you a discount for this stuff are not being paid off by Bosch and Denso.)

(As a hypothetical example of the scientific vs anti-scientific views:) If your Toyota bursts into flames when you turn on the radio, does that mean all Toyotas are bad? Engineers and scientists would claim that you can't say without doing the science and statistics. The uneducated common man tcmtech praises might say "Yes, all Toyotas are bad because mine burst into flames when I turned the radio on." The uneducated common man may believe in Santa Claus, and no one can dissuade him, because he doesn't have the educational basis for making scientific determinations.

That is not necessarily a bad thing for that individual. Fat, dumb, and happy. What's wrong with that? It sure beats worrying.

On the other hand it can be a bad thing for the rest of us. There are too many people (in my view) who, like tcmtech, believe that the law is for others, and not for them. So, like tcmtech, they are willing to violate the emission laws (by removing all emission control equipment, as he has proudly claimed elsewhere) for what they perceive as personal gain. The number of uneducated rednecks who do this is very small however, and many do not live in highly-populated areas, so the damage to the environment is probably unmeasurably small. In a large city, however, the effects of high concentrations of NOx (more than half of which comes from motor vehicles, depending upon the city) are damaging to the health of the very young, the very old, asthma and emphysema sufferers, (and others, to a lesser extent we can assume.)

So while I don't buy into the noble redneck anti-science, pseudoscience view of things, many people do. I am not writing to those people -- they are lost, in my view. Nothing I say will convince them, because they operate out of blind belief rather than out of science and rationality. It's like arguing with the perpetual motion freaks -- which I have done enough to see that only 1 out of 50 will even change their views slightly.

To the others, who actually have a clue re science and engineering, I can say (and they can easily verify) that yes, engines have gotten much better (in every respect other than simplicity) in the decades since emission controls were implemented. Output per liter is far higher, output per pound of engine is higher, BSFC is much better, and on the whole-vehicle basis, mpg-ton has gone from 24 to 46 between 1985 and now (which is from the combined factors of engine development, better transmissions, slight improvements in aerodynamics, lower rolling resistance tires, the influence of hybridization on the overall fleet averages, and higher vehicle density -- i.e heavier vehicles with lower frontal area). To these people, (the scientific types) I'd say pick up the most recent issue of Motor Trend, which traces the history of the best-selling cars through the last 5 decades, and which confirms that every aspect of performance has improved. To confirm that the fleet average weight has gone up, either 1. look around you, or 2. read the actual numbers, (either in the quite good Motor Trend article or in Wikipedia and 1000 other places on the web). Since the mid eighties, average vehicle weight has gone from about 3200 lbs to over 4000.

The people who think that cars were highly-efficient in the old days are, generally, either completely ill-informed and too lazy to become informed, or part of the anti-science redneck crew, who do not have the capacity or desire for understanding the science. Even though it is simple to find road tests of old small cars, the intellectually lazy will not do so, preferring to live in a fantasy of the "good old days." In this old test of the Corvair Monza, the Mustang and the Barracuda, (scan down to page 93) at a constant 60 MPH, these smallest Detroit cars got 16 - 18 mpg, even though they only weighed about 3000 lb, (roughly 800 lb less than a typical mid-sized car of today). To the fantasy crowd, tests like these make no difference, nor are the highly-repeatable EPA tests valid for them.

Science and engineering types who take the time to compare the EPA mileage figures with real world results, find that there is a very high correlation. (Go to the EPA site an compare owner results for the Prius with the tests.) Prius owners, when averaged out, get essentially the same numbers that the EPA gets. (This is true for most other models as well, when the sample size is large enough to be meaningful.) Science and engineering types will always value EPA dyno tests, which are extraordinarily thorough and repeatable, over the BS that anti-science types spew.

So, to those people with intellectual curiosity and a little background in science and engineering I say: Look it up. You will find that what tcmtech claims has no basis in science. Nor, to his credit, does he claim that his figures have any basis in fact. He says "I have always found it strange that engineers, and politicians, have all of these facts, figures,and numbers..." Engineering and science rely on facts, figures, and numbers. To these scientific types I would also say, (getting back to the thread topic) research the use of throttle by wire, etc, and you will find that these systems are (in general) very positive things, and that most manufacturers who use such systems (essentially all of them do now in various models, and some, like Suburu and Mazda have used throttle by wire on most of their cars for a long time).

Politicians and engineers are not getting together to see how much they can screw people over with their facts and figures. Most of the these improvements have been driven by the market, and most are things that people have willingly paid extra for on luxury cars first, and then eventually trickle down and become less expensive.

To the others I say -- sure, trash engineers and scientists... loads of people do. If Santa Claus exists for you, and if you think your HHO device is doubling your fuel efficiency, that's fine -- just don't offer it for sale and then cry when the FTC shuts you down.

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#5

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/11/2010 11:35 PM

I hate to be the one with a bucket of cold water (actually I don't, but I'm a polite Canadain), but going back to throttle cables and linkages will not eliminate any problems. Do you not remember cables breaking, sieizing up or fraying and slipping as well as return springs falling off and ice forming on--well those in warmer climates may not have had that problem?

One thing has to be clear that Canadian equipment on Toyotas such as floor mats are different than US ones. Canadian ones are thinner and of a different rubber compound due to the need to operate in a more diverse climate. That is why the floor mat issue is an American issue. Thick floor mats can cause problems, I had an Escalade that the owner turned the floor mats over so tht the rubber side was up and they got stuck under his gas pedal and caused the gas pedal to jam open. Fortunately he had the foresight to put it in neutral.

As for shutting a car off or putting it in neutral. Nobody thinks of that in an emergency. Tests have shown that using the brakes as hard as you can will stop a vehicle from 120 kph (about 70 mph) with the throttle wide open. The only thing is you only get once chance since the engine isn't producing much vacuum. If you have the presence of mind to put it in neutral the engine still does not produce vacuum so the one shot at braking still applies. After that how fast you stop will depend on how scared you are, because you will need plenty of force on the pedal to stop the car.

If you try to shut it off, many people will have trouble getting from run to off without going all the way to steering wheel lock. In addition, with the car off, you loose power steering and revert back to very high effort steering. One other point that makes shutting things off difficult is that many cars are now push button and the button has to be held for three to five seconds before the car shuts off when in gear.

I am not convinced that the acceleration issue isn't mechnical as I've seen the component on a work bench and can see a couple of different ways that it could fail. I'm not a software engineer or an electrical engineer so I can't comment on how those componets could be compromised.

The biggest and most multi-faceted problem in this issue is political. Toyota had set itself up as better than anyone else in the world. They have now shown that they are not. Worse yet is the idea that Toyota is only the first company to have a problem like this. With the growing complexity of automobiles the risk of a serious flaw gows exponentially.

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#7
In reply to #5

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 2:31 AM

I intend to use at least one of these reported events as training. I work with electric drive off highway vehicles. With these vehicles the primary means of slowing the truck is the retard system which is regenerative.

Standard procedure if you are going too fast as you go over the ramp is to apply the service brake as if you want to stop the vehicle. Feathering the brake will only overheat it.

The same goes for Prius or other passenger vehicles. One (Pruis) event was reported in Australia a couple of days ago and when the copper involved instructed the driver how to use his brakes, despite them already being overheated, the vehicle started to come under control enough for the copper to utilise bis own vehicle brakes to complete the stop.

Your mention of the correct use of brakes is why I've given you a GA.

Every day I see drivers (especially of automatics) abusing their brakes. When I'm coming home from the Coalfields I see a row of brake lights illuminated all the way down the range (12% gradient). Dropping down a gear seems to be impossible for many "drivers".

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#9
In reply to #5

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 5:51 AM

I dissagree slightly with your comments:-

On my Mitsubishi, I get between 3 and 5 brakings with good help from the booster before its empty.

So if you pump the pedal (not needed with ABS!, you will empty the reservoir quickly.

But if you stay on the pedal as hard as you can, you won`t empty it (unless you have vacuum leaks or some other unfixed problem of course!)

Diesel & Turbo diesel and most/but probably not all petrol turbo cars have a separate vacuum pump that actually works better at high revs......useful in such cases!!

On some cars its part of the alternator (at least on the ones that I have looked at!!)

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#10
In reply to #9

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 7:02 AM

Most passenger cars suffer from underrated brakes. While the vacuum is one issue, brake fade from excessive heat quickly compounds the the problem to the point where the brakes act at a fraction of their capacity. Under extreme duress, drivers tend to apply huge amounts of brake pressure due to adrenalin rushes, which help to overcome some of the loss of vacuum, but brake fade is another matter.

That issue exists with the brand new brakes. Worn or partially worn brakes aggravate the issue further. When brakes heat up the brake fluid actually boils inside the caliper.

Under ideal conditions, the brake rotors should act as a heat sink and the pads as a heat shield.

It always amazes me when I look at all these passenger cars and see these tiny little rotors and the tendency for people to ride those brakes. Small brakes, worn pads and rotors, and bad driving habits all contribute to the problem.

I guess another issue is that people really could not be bothered to really learn about driving defensively. We have reached a stage where one of the more important car buying criteria is the number of cup holders, the radio and entertainment center, interior comfort, color, status, and the ability to run over pot holes and rubbermaid trash cans without feeling them.

People just want to exert the minimal effort, without thinking of what happens inside the box, to get from point A to point B in the greatest style and comfort that their money can buy. Most people can't even change their own tire.

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#25
In reply to #10

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 1:47 AM

In my field of work electronic throttles have been around for quite a while and before that air throttles were used. Cable throttles haven't been on big gear for 40 years at least.

The keyswitch can't turn off the control power until the vehicle has stopped moving. This feature was introduced to protect operators from themselves, preventing the selection of angel gear.

There is however a killswitch, accumulator backed hydraulic brakes and steering and spring applied park brake to complete the safety package. None of these things exist in the average passenger car.

Lack of these items make the idea of a push button start in the "Windows" style look a bit dodgy.

Having laid out the kind of safety features that are part and parcel of Off Highway Vehicles, I now have to say the hardest thing is getting the operators to use the gear correctly. If operators who must be assessed as competent for each piece of gear they drive can't get it right, we probably can't expect too much from Joe Motorist.

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#26
In reply to #25

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 6:46 AM

I think the idea of a reset or kill switch in a car is going to meet two hurdles.

1. There is the issue of accidental engagement of the kill switch while driving. Yes, there will be lawsuits the moment someone accidentally hit is and causes an accident. Where do you locate it so that it can be easily accessed, yet not accidentally engaged by the driver or an irate passenger. Then there is training to use it (remember, lowest common denominator). Control-Alt-Delete syndrome.

2. From a marketing perspective, who would want to buy a car with a kill switch? It implies that the car isn't safe in the first place and they had to install a backup safety device incase of a catastrophic system failure or a HAL moment. At least that is the perspective of the buying public.

I think the first manufacture that installs a kill switch sill see their sales killed because the perception is that the manufacture is admitting guilt of a dangerous or unpredictable system in the car.

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#27
In reply to #26

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 7:57 AM

I ran across this last week

Special Report: Tomorrow's Car

See All Special Reports »

[1]

2 Next »

Toyota Applies the Brakes

The company hopes a "smart pedal" will help defuse criticism.

By

Kristina Grifantini

Full article

Thursday, March 11, 2010
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#28
In reply to #27

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 8:03 AM

I got a little tangled up in the formatting

so I'll post my comments here

The smart pedal seems to be in effect a kill switch

the omission [in the original designs] was the real fucq up

the alarms & faults are the hardest part of coming up with a comprehensive truth table

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#33
In reply to #28

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 7:45 PM

Hill start logic etc is certainly not new and you have to wonder why it took a crisis to bring these catch up changes.

The side effect may be to eliminate left foot braking (or at least the effect of it), the hidden villain in all this.

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#35
In reply to #27

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/16/2010 12:36 AM

Interesting article, as is the Popular Mechanics one linked to it. This is a proud moment for Toyota -- bringing out technology today that BMW had 22 years ago!

One would hope they come up with something better to call it than "smart pedal." Invites questions like "How friggen smart are these people if it took them so long to figure out that the brakes should override the throttle?"

Let's me see if I have the history right.

  1. There is no problem. Bad drivers.
  2. Whoops, it's the floor mats: here are some wire ties.
  3. Whoops, it's our sticky throttle pedal. This shim might help.
  4. Whoops, we forgot to include an override. Our pedal used to be dumb.
  5. Whoops, we should not have used Windows 95 for system control. We were going to upgrade to Millenium Edition, but it cost too much.
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#32
In reply to #26

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 6:22 PM

Well put.

The key switch has worked well as a kill switch and so long as it isolates the power it is a case of, "If it ain't broken don't fix it".

If soft controls continue to be installed (and customers continue to buy them) kill switches or seperate isolators may be the only solution.

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#8

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 4:58 AM

There are I'm sure many explainations for crazy things happening involving electronics. Just one intermittent ground connection can drive even the most experienced tech nuts. This is where we are today. I guess we could call it progress. What do you suppose will happen next after sudden acceleration problems?

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#13
In reply to #8

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 10:24 AM

What do you suppose will happen next after sudden acceleration problems?

Sudden stopping problems?

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#12

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 10:13 AM

Speaking as an embedded/real-time system programmer:

I may be giving people way too much credit, but I find it slightly hard to believe that all these loss-of-control events involve people not applying the obvious solution. Note that very many new cars have electronic ignition and entry systems, which implies control by software or firmware. Thus, you might have to ask permission of someone's software just to turn your car off.

We are told in our entry-level computer science courses that there is no such thing as a correct program. Even "hello world" can fail a rigorous mathematical or logical proof. I remember seeing electronic power switches making their way into consumer electronics, and not appreciating it one bit. Didn't anyone learn from "The Ultimate Computer" Star Trek episode??? How the hell is Kirk supposed to save the ship/planet/Federation if he has to ask the computer for permission to turn it off?

Automatic stability control is okay, but it'd be nice to be able to disable it temporarily. Electronic fuel efficiency control is acceptable, and heck, I don't even care anymore if it robs me of the last 10% of engine power - I'm not going to race my car. Hook the lights, radio, wi-fi, head up display, to a logic circuit - fine with me. Even electronic braking is something I can live with.

But I require an emergency mechanism to remove power from the device with 100% reliability! I am not willing to trust my software to provide a fail-safe when my life is on the line, and I'm not about to trust anyone else's.

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#15
In reply to #12

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 11:38 AM

"I am not willing to trust my software to provide a fail-safe when my life is on the line, and I'm not about to trust anyone else's."

Obviously, you don't fly, drive, take public transportation, rely on emergency medical aid and so on.

You would be amazed at what's around you that is a safety critical device. Beyond aircraft and transportation, but even these contain subtle devices that we take for granted. Do you look both ways every time you cross an intersection that is green? I try to look, but many times you can't see left or right well enough to be certain that nothing is coming nor can you tell if the light has malfunction for the other driver.

If you have an electronic controller in your oven, chances are you rely on embedded controls from blowing up your kitchen when you engage clean mode in your oven. Ever open an oven door when it is in clean mode? The resulting in-rush of oxygen causes a rather spectacular explosion.

Truth is that we rely on life critical software more than we think.

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#16
In reply to #15

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 11:58 AM

You are right, of course. I don't trust anyone else's software to preserve my life, but I usually don't have a choice about it. I would have liked to have been in on the discussions where it was decided to start putting software in control of power or similar essential systems. Who knows, I might have been persuaded that it was a good idea.

Of course, software isn't the only source of failure in a system, and sometimes there really isn't a choice about putting a CPU on life-support duty. But there needs to be a damn good reason to do so, because software is generally the most complicated and frail part of most systems.

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#17

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/12/2010 2:52 PM

my response is here.

Chris

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#21

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/14/2010 6:07 AM

I have had two related problems, but with BMW's.

In about 1970 a spring disengaged whist I was at a police check point in Zambia and the engine went to full throttle - embarrassing but safe as it was in neutral.

In the UK I had another secondhand BMW but with a solenoid activated throttle that eventually decided life wasn't interesting enough and would race and loiter at will (its).

The solution was to cut out the electronic control and instal manual twin webers, which turned out less hairraising and more fuel efficient.

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#30
In reply to #21

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 4:07 PM

I shall reply to myself.

The failsafe we have on our cars is the foot operated clutch, and if that failsafe fails we turn the ignition off.

Automatics aren't for real drivers, they're for people like that .... who parked, (I thought) then reversed at high speed with one arm on the steering wheel and the other hand clamped to his ear, just as I jaywalked behind him.

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#31
In reply to #30

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 4:58 PM

The ratio of automatic to manual transmissions is completely reversed in the US compared to Europe.

Come here and try to get a rental car with a stick.

We'll take Visa, Mastercard, American Express, but no sticks.

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#34
In reply to #31

Re: Ditch Drive-, Brake-, and Steer-by-Wire?

03/15/2010 11:14 PM
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