In the old days of a cable linkage between the accelerator pedal and the carburetor, my brother had the experience of the return spring breaking. He turned off the ignition and the car stopped. Another option is to put the gear selector in Neutral. If you are truly concerned that the car won't stop, I don't think you will be worried that the engine will overspeed and throw a connecting rod. But then that would stop the engine. I do agree with having an interlock between the brake pedal and the electronic throttle control, but technology can't replace good driving skills.
Yes but..good driving skills may include keeping the brake pedal depressed while giving the vehicle some gas when starting up on a steep hill so it won't roll backwards. Thus, the interlock firmware needs to be intelligent and not override the throttle the instant both both pedals are activated.
bdcst; Some vehicles have 'hill start assist' that maintains braking for a short time to allow time to press the accelerator. Rolling backward was more of an issue when the clutch pedal was also present. Some drivers have the (bad habit) of 'two-foot' driving; one foot on the accelerator and one foot on the brake; poor mileage, poor acceleration, brake pads wear out quickly, the driver following can't tell riding the brake pedal from actual braking.
I would think manual transmissions would be exempt from this measure. Other reasons (besides starting uphill) could exist that the operator might want or need to press brake and accelerator at the same time.
The manual transmission is about the operator having control of power delivery rather than the machine having control over it. Drivers who prefer manual transmissions are generally going to be of a higher skill level and less likely to forget that there are numerous ways to stop unintentional acceleration - and the clutch pedal is right next to the brake. (Yes, I've been using manual transmissions on a wide range of vehicle types for over 30 years. I started very young.:))
I can see why the automakers are on board with this. It's a simple, cheap, technical solution to an ongoing problem. It's also going to be one more big hassle for competent drivers who have occasional need to do things slightly "outside the box". The first thing I would do if I bought such a vehicle is bypass the brake actuation sensor.
I can think of three main occasions for applying the brakes and throttle simultaneously. Starting on a hill with a stick shift is the obvious one. The less obvious ones are drying the brakes after driving through water, and increasing traction when one wheel is spinning on ice or gravel and the other is on bare pavement. In such a situation, with an open differential, a bit of light braking will sometimes slow the spinning wheel enough that enough torque will be transferred to the wheel with traction to get the vehicle moving.
There may well be some techinical problems with drive-by-wire systems in which a malfunction could cause the throttle to stick open, but the bottom line is that all these "stuck throttle" cases come down to operator error. Most of the time, the driver is frightened or feeble-minded and accidentally reacts to unwanted movement by pressing the wrong pedal to the floor. Even a brake-throttle interlock is not going to prevent that problem, which has been around as long as there have been automobiles with throttle pedals.
Even if the throttle genuintely sticks, however, a competent driver should be able to use the brakes to stop the vehicle and stall the engine. A brake system on a light vehicle can generally absorb 10 times the power that the engine can put out, albeit for only a short time before overheating. A hard brake application will always stop the vehicle. The trick is to brake hard and not give the brakes time to overheat.
On a modern vehicle, turning off the ignition switch generally closes the fuel solenoid, which is also certain to stop the engine. On older vehicles, an engine may keep running at high speed even with the ignition off, but once the brakes have brought the RPMs down, the engine will stop if the ignition is off.
The real problem with "stuck throttles" is incompetent drivers. The smarter we make the cars, the dumber the drivers seem to get. It reminds me of the old adage that as soon as you invent a fool-proof device, nature will come up with a smarter fool.
Very well put, D.Sherman. There are numerous reasons to use the brake and throttle simultaneously (some were also mentioned by ChasChas and I have had more come to mind).
It just makes the auto makers "look good" in the media's eyes if they "do something" about their problems even if it forces us all to drive like feeble-minded, unskilled drivers. It also makes their attorneys happy.
Not really. While a manual transmission obviously requires hill holding skill for even the mildest incline, steep roads will even cause an automatic to roll backwards as the idle speed does not produce sufficient torque through the converter. First hand knowledge, don't ya know. :-) But either way a gas/brake interlock has to be smart and tolerant or it'll be an annoyance at best and dangerous at worst.
I think that trying to get to feature to work in software and co-exist with times when you might want to depress the throttle and brake is an exercise in futulity.
The 'safety' feature needs to exist apart from the normal throttle, brake and gear shift controls. We already have plenty of experience providing this type of safety system.
I am amazed that auto manufacturers haven't had to do what industrial equipment makes have had to do--- install a big red e-stop (panic) button. When we still had mechanical keys we effectively had this.
Now that electronic 'keyless' systems have been in wide use, we have lost the method for shutting down a misbehaving system and this current condition was bound to happen.
It seems somewhat unfair that Toyota's acceleration problem got so much press when it was first examined, but when the cause was not found to be a software or electrical issue the media was mute. If the driver doesn't panic there are plenty of methods to disengage power by shifting into neutral or turning the car off. Adding this additional method to cut power in drive by wire systems wouldn't add any additional hardware, and would remove power even if the driver panics.
I agree with you, tekochip. Although there was a fair amount of media coverage when the Secretary of Transportation made his pronouncement, it paled by comparison to the amount of coverage the story got when it orginally broke.
This whole controversy is just plain dumb. A simple shut-off switch operated by the brake pedal to turn off power to the injectors would solve it- All the manufacturers would need to do is use the stop light switch on the brake pedal to power a relay that killed electricity to the injectors and fuel pump when activated- no more issues. Period. A $5 solution. What's all the fuss about?
Chuck_IAG, On calling this "this whole controversy" "just plain dumb", I think you've missed the point many of us are making: We want the engine to function normally when the brake is pressed. That is what accomplishes the effects we are describing. It is all part of being a skilled driver rather than an unskilled one. You might benefit from reading and thinking through some of the described methods listed.
A shut-off for injector power that is triggered by the brake pedal would defeat all of these advanced driving methods.
I think it's a mistake to overthink this, but engineers are great at doing just that. It may be an effort to ensure continued employment. Simply placing one's foot on the brake to flash the brake lights could be considered inelegantly simple, but it works and that's how it's done. You don't need an accelerometer to verify that the car actually is slowing down (preventing false light flashes) and volumes of code in the ECU. Just do it and be done with it. Simple.
Same way with the acceleration/brake override.
All the conversation about how the user is at fault reminds me of the IT gurus who say that unless the PC shows the same fault when they look at it, it never happened to you either. Sometimes you just can't replay all the pertinent details of the event to reproduce it; that doesn't mean it didn't happen, just that you don't know what all the variables were.
I'm sure someone could come up with some "elegant" solution that requires crossing your fingers when applying the brakes to kill the fuel supply, along with an onboard camera to detect the finger-crossing and 2 million lines of code to interpret the gesture. Sound better guys?
I wish to express my outrage at the lies contained in this report!
In its investigation NASA found examples of throttle sensors that had grown Tin wiskers that shorted out the pot's leads effectively indicating a full throttle command. The web link to the NASA paper is here: http://nepp.nasa.gov/whisker/reference/tech_papers/2011-NASA-GSFC-whisker-failure-app-sensor.pdf
This is an example of an undesirable side effect typical of every human endeavor. In this case the desire to eliminate lead from solder has resulted in a proliferation of tin wiskers causing no end of trouble in electronic circuitry.
I would question the use of carbon potentiometers for this critical throttle control application. D.C. voltage applied to a carbon pot makes it go noisy rather quickly . I'm not aware of a single carbon volume control pot, which by the way is normally only subject to A.C., that I've owned that hasn't got noisy within 10 years of use. We're talking about blow your speakers type noisy.
In one report on the Audi runaway problem, the engineer was able to readily reproduce the runaway problem caused by alternator noise wreaking havoc with the controller CPU when the battery's impedance rose at high temperature extremes.
It's obvious to me that both of your mentioned reports were written by the industry friendly mandarins of NHTSA and NASA. These do a major disservice to the hard work of some honest engineers, who take due diligence seriously, especially when people's lives are at risk.
Lighten up, "cookiejar." Your indignation about this matter is very selective. On one hand you refer to the "industry friendly mandarins of NHTSA and NASA." On the other, you cite a NASA pdf file to make your point about tin whiskers. The fact is, NHTSA's final report cited tin whiskers on pages 46, 48, 69 and 74 (those are the pdf page numbers), proving that it was aware of the issue. In the end, though, the report concluded that the tin whisker effect is not dangerous. Its conclusion was that it would have been impossible for tin whiskers to cause the Toyota vehicles to accelerate out of control. As I noted in the story, the Secretary of Transportation emphatically stated that the verdict was in: "There's no electronic-based cause for unintended high-speed acceleration in Toyotas. Period," he said. For this story, we also talked to the Center for Automotive Research and Consumer Reports. Reports by the National Academy of Sciences and by Edmunds.com have reached similar conclusions. If you can demonstrate that tin whiskers were the cause, I strongly suggest you call Edmunds, which offered a prize of $1 million to anyone who could demonstrate "a novel cause for unintended acceleration." If all these people are in on some kind of conspiracy, it must be a whopper.
To see NHTSA's final report, go to the following page and click on the link that says "NHTSA Full Report":
No sane engineer would waste his time and money trying to collect the $1million prize for finding the problem with Toyota throttle controls. Firstly, the lawyers would have made it impossible to collect with the fine print. Secondly, how would you find the intermittent vehicle, let alone the intermittent fault without total access to the technical documentation? It would take one a long time to get familiar with the technical hardware and software details. I guarantee you that Toyota would not be particularly friendly to you. Let's face it, your life would be destroyed if you are shown to be a whistle-blower. It's human nature.
In the 70's I owned a Ford farm tractor which had the standard issue Ford lap-belt seen in all Ford vehicles. What disturbed me was that whenever I went over the very bumpy plowed sections of the field, the lapbelt would release by itself. Closer examination of the construction showed the hinged cover folded back so its ends were flush with the back face of the belt buckle. What was happening was that the fat in my stomach (6'4" 175lbs at the time) when I was pushed into the buckle would push the cover out and release the belt. I could demonstrate this release mechaism by simply leaning into the belt buckle. I wonder how many people died wearing this belt, and were recorded as seat belt not buckled. Oh the humanity! When I contacted Ford, they asked me to mail in the belt. The new belt I then bought had the back wrapped around the side avoiding the problem. So Ford engineers obviously knew what was happening and had quietly fixed the problem.
You mentioned "tin whiskers" and I have some recent experience supporting this hypothesis. For several years, I've been 'rebuilding' 2001-03 Prius accelerator assemblies. A dual-pot encoder, when they become "noisy" the control computers detect this and trigger a safe-home mode. This caused the vehicle to behave as if a big-hand was holding the vehicle back.
The replacement accelerator assembly cost ~$500 not counting labor to install. So Doug Schaffer figured out how to rebuild the encoder and I carried this on when he went to China. A simple process, we used a Dremel tool to remove the cover and clean the contacts and surfaces. Reassembled using JB Weld epoxy, it was a cost effective solution. But eventually with the low volumes, I stopped doing this. Then I read the 'tin whisker' papers from GSFC.
I still had a number of 'broken' encoders so following the procedure described in the papers, verified the broken ones had similar characteristics. Then using a 9 V battery to 'burn out' the tin whiskers, I retested them and their failure symptoms were gone.
Modern encoders are Hall effect devices, not dual-pots, so the tin whisker threat is significantly reduced. Furthermore, the older 2001-03 Prius are going out of service and the data suggests these problems were limited to the first year or two of production. The 2003 model year encoders haven't shown similar failure rates. Regardless, 'burning out' the tin whiskers turned out to be a simple and effective solution.
The gas pedal sensor has been called a potentiometer, and now a dual-pot encoder in these posts. A 'pot' or potentiometer is not an encoder. Does someone know the exact nomenclature of this device ? The encoders that I am familiar with are optical = led's and a rotary grating.
I find it telling that Toyota was still using carbon pots for the critical throttle position sensor, while at that time the whole automotive industry had long abandoned carbon pots for digital encoders for the volume control of their car radios, because pots were too noisy.
Not that other sensors aren't susceptible to analogous disturbances.
A couple of months back I took a new Toyota Sienna for a test drive. After all, it's the only van "recommended" by Consumers Reports. I found it very difficult to control its speed. Even on a flat smooth and level road, with my foot braced against the center console, the car would slow down and speed up by itself making driving tiring. When I engaged the cruise control, everything settled right down. As you may expect the saleslady with me denied there was anything wrong. Apparently she gets these paranoid test drivers all the time. My hunch was a throttle control problem - still.
How does one go about checking 280,000 lines of code? One immediately thinks of Microsoft Windows, which gets updated ("corrected") weekly. A car manufacturer doesn't have this luxury.
Today's development cycle is highly cost and time constrained. How often have you heard the announcement, "Well, it seems to work. Let's get it out into the field." Further tests are costly and would rob our lead in the marketplace. Then when problems develop in the field, it's always the "stupid users" fault. Wouldn't it make sense to design with the "stupid user" in mind? We can blame it all on human nature's tendency to pass the buck and blame the victim.
Let's just give a thought to how many of our electronic devices have failed in some way in the last 10 years. Couldn't most of those failures been avoided by better design? Same old - same old lousy engineering. We're all human after all.
The mentioned dual-pedal-application fix, and the many posters problem with it preventing intentional dual pedal use when needed could be remidied by having a timer delay in the software coding, say requiring 3-5 seconds of continuous dual pedal application to trigger the shutoff. That would allow the occasional valid use of dual pedals that is occasionally useful, and yet maintain the shutdown feature when it is really needed.
What gave me a clue that something else was going on was none of the cleaning swabs were coming out with observable debris. The wear surfaces did not show pitting or other visible defects. But we knew opening and cleaning seems to clear the symptom.
Hind-sight, I suspect tin whiskers which are all but invisible unless using a microscope were shedding and falling into the various wiper areas. Whatever it was, it was not visible to the naked eye.
The NASA GSFC paper pointed out that VOMs would detect the resistance anomalies but were not enough to 'burn' the whiskers. I could see as the encoder was advanced, the resistance would drift. So I tried the GSFC approach, apply enough voltage to 'burn out' the whiskers.
I simply used a 9V battery in all combinations of the six pins while cycling the encoder. I didn't bother with trying to monitor the current to detect the 'whisker burnout.' Regardless, retesting the encoder shows the resistances were now linear with displacement.
There may be some aspect of carbon traces that I'm unaware of but the absence of debris on the cleaning swabs was pretty telling.
TIN WHISKERS!!! As an engineer in the electronic components industry, our products are specifically EXCLUDED from the ROHS mandate BECAUSE of the TIN WHISKER "problem". Our products are installed in designs that are as close as your local telephone pole, and as far away as the orbiting satellites, etc. The industry has recognized the potential for failure inherent in the use of these parts, where the TIN WHISKER migration is a definite possibliity. By the way, this phenomenon is not only limited to non-PB solder, but there is also a well-documented history of silver migration, which engineers & designers MUST be aware of when manufacturing electronic products.
Here's another solution looking for a problem. I do not like idea of putting this on every car in the universe simply because a few people fail to hit the correct pedal. I am tired of seeing this panic everytime a problem like this hits the news. Yes, its unfortunate that someone gets hurt or killed, but life is full of risk.
Besides - If we are still in the land of the free and home of the brave, (not sure about that anymore).. I would really like to retain the option to hold the brake and roast the tires. OR - at least know that it is still possible even if I'm too much of an old fuddy-duddy to actually do it.
I have had this problem on my 2010 Subaru on occasion. It is not an electronic problem but is an unintended consequence of crash safety which dictates a constrained foot area. Because crash safety dictates a wider bell housing bump in the floor pan, the accelerator must be positioned leftwards from it's historical location (read 1960's American cars). In fact the accelarator and also the brake pedal are so far left on my car (and Toyota's that I have tried) that it is actually painful to hold the brake pedal when stopped. On occasion I haven't moved my foot far enough left to completely remove it from covering the accelerator when stopping. To exacerbate this problem, the Subaru, like many other cars with ABS and power brakes has a very mushy brake pedal. The brake has almost as much travel as the accelerator. So unlike cars with a rock hard brake pedal, when braking if the right foot is covering both pedals, both pedals will travel sufficiently to increase torque from the engine while applying brakes.
I do not agree with the NHSTA that some electronic fix is necessary. The NHSTA should require that brake pedals be "hard" when operational with or without power assist or ABS. Then the two pedals, brake and accelerator will have different tactile feedbacks.
In addtion the NHSTA should require that the placement of the pedals not cause undue stress on the foot and leg when using the brake. In other words the accelrator and brake pedals should be moved slighty to the right.
Having the engine not accelerate on a stick shift while braking would make downshifting nearly impossible on a manual transmission vehicle where the right foot is used to operate the brake and throttle simultaneously.
I hope they include a mechanic's override. They like to hold the brake and rev to check for bad motor mounts, a weak brake, sputtering fuel problems, erratic spark, muffler noise, etc.
And keep it off our airplanes - we still plan to hold the brakes, rev and check the mags or minimize roll in a short field by checking if we have full power without moving and then let 'er go like a slingshot.
Especially at local John Wayne Orange County Airport (SNA). The short 5600 foot runway and steep noise abatement climb makes SOP for airliners: Position and hold / Full power with brakes / Takeoff roll. Not an issue in my C150 but still have the runup and mag check, of course !!
After over 45 years of engineering, how do I go about checking someone else's system with 20,000 lines of code?
Let me explain my technique on a simple system - one digital input from a sensor and one digital output. Using a SPREADSHEET I would generate the usual family of waveforms - sine, square, triangular, noise etc. of the broadest frequency range making sure that a family of values would go well into clipping and overload. You want to generate every value that can be coded on all the available bits.
Then I would output my sets of waveform values to a file and use a simple program to convert them into the digital input format of the system under test. The digital output of the system I then convert with another small program into a format the spreadsheet could accept and then plot.
On my spreadsheet I would have graphs of the system input waveforms and graphs of the system output waveforms. This software test method is analogous to testing an audio amplifier for performance under all frequencies waveforms and levels, including of course overload.
Multiple inputs and outputs are handled similarly. Analog input simulation is handled by D/A converters and analog outputs by A/D converters.
To be honest, there hasn't been a single system that I've tested in this fashion that hasn't shown some expectantly erratic behavior. In many cases it has lead to much simpler and elegant coding, because you actually see what your program is doing. The big secret to this method is that you deliberately test every single value including overloads. Don't forget to test common mode and normal mode input values and noise.
I get a real kick out of seeing bazaar software behavior. And of course, a great sense of satisfaction of having contributed to a truly robust system once the problems are licked.
This is fixing the wrong thing. The machine isn't broke, the drivers are. You can stand on the accelerator and brake pedals on a 600 hp Corvette and it won't 'override' the brakes. You can also turn off the key...(I know the steering locks, but that's better than headon at full throttle into whatever is in the way.) And why does the steering lock? Another answer to trying to fix stupid. This proposed fix will create problems for those mechanics, read drivers, and others who know the difference between the pedals on the floorboards of whatever they are driving.
Steering DOES NOT LOCK, unless you remove the Ingnition Key.
The Key removal activates the 100% mechanical spring loaded steering column lock - has been that way since 1966 !!!
On vehicles with automatic transmission it is further impossible to remove the key if the car is not in PARK - if it can be it is a DESIGN DEFECT and would have to be corrected under FMVSS.
On vehicles with a "STOP/START" button there are no clear rules as of yet how to stop EVERY vehicles in the same way.
No mater how many millions of line of CODE you examine there always is the random occurence that may be as rare as a win in lottery - but it CAN happen!
How many times in your life have you pressed this or that key on your computer key board, and the intended or expected event did not occur ?
In case of a car you are betting your and other persons life that such desired event will happen 100% of the time under all possible combinations of conditions....
The alternative is to LEARN how to drive and buy only vehicles where you as a driver have 100% control over the output buy you providing conscious and intended input.
The NHTSA basically took your master decision out of the loop and now you are only allowed to "suggest" to the vehicle what you would like it to do - i.e. drive by wire - and IF the vehicle decides to obey you, it might, if it does decide it knows better (ABS, ESC, etc.) then it will ultimately DO WHAT IT WANTS and will disregard your input.
When driving a manual, a useful technique is heel/toeing where you apply the brake and blip the throttle so you get a clean downshift. This "solution" would preclude doing that. It would make downshifting in low-friction conditions more dangerous, because the revolutions of the engine & transmission couldn't be matched as well. Then again, manuals seem to be going the way of the dodo these days...
Kind of 37 seconds ago. Enthusiast cars are already chipped and or driven with the laptop hooked up to the car's computer. The rest drive Camry's and step on the gas when they need to employ the BRAKE. OBTW saw the Google autonomous Prius driving itself on public roads with humans on board, now that's cool.
I cannot beleve some of the posts on this site. Turning you car OFF will not lock the steering wheel the car must be in park for it to lock. Try it in you drive way someday start you car put it in drive and turn it off and see if you can lock the wheel. Make sure the brake is on at all times. As for driving with both feet which is a pet peeve of mine I think that would take a lot off drivers off the road itself. This is knee jerk reaction by the goverment and a very poor soultion at that. Fixing the problem and educatioing the public about what to do is whats needed.
I think it's a bad idea. I say that as both an auto enthusiast and former automotive engineer. It's kowtowing to the lawyers and the safety lobby. It's another reg that adds cost to the vehicle. Cost that the beancounters offset by sourcing more stuff from China or other LCC's.
I lump this idea in the same bucket as tire pressure monitoring. I call that bucket "trying to engineer away stupid." Besides, who came up with pushing both pedals? Pushing both pedals to the floor is only what brainless, completely inept operators do when they panic. Why not have a big red E-stop button in the car is you must. You know what preproduction prototypes and mules have to prevent such problesm? That's right, a big red emergency stop switch. It's obvious and it's universal.
This idea kills the cable throttle, although I'm not sure anybody uses one anymore. Personally, I think drive by wire is crap, especially with a manual trans. Of cours they don't build many manuals anymore because "American's don't want them" which is code for "we don't want to build them because they cost more to build and require a stronger driveline since they can't be torque managed as effectively" but that's another argument.
I do agree that there are some situations where you need to push both pedals although you probably wouldn't use WOT at the same time as the brake. Limited traction scenearios such as snow or mud come to mind. A trained driver may also use throttle and brake at the same time with a FWD car in an understeer condition.
Finally, and most important, what about burnouts? They need to include a way to disable this silly feature for burnouts. Or else maybe include a switch that would use the factory ABS pump as a line lock?
I have to harken back to the 1970's when this same agency had their last "deadman" idea. The bright idea at that time was to make it impossible for you to start an automobile if the seat were cccupied but the seat belts weren't fastened. I can remember being out on a business trip with my boss and having to have both of us lift our bottoms off the seat to trick the car into starting. That lasted until someone yanked the plug on that "brilliant" safety feature. It lasted one model year.
Can we ever be "safe enough"? Not to a "safety engineer". This is often brought upon us by greivng parents whose child was killed or maimed by a accident. I detest the adjective "tragic" or Tragedy because it is so over used as to be meaningless. These folks become crusaders, attach themselves to some mindless politician and get another bad law passed to keep the attorneys and cops busy. If our Legislators concentrated on the Economy, the loss of manufacturing industries and on jobs instead of these "feel good" laws we wouldn't be in the economic mess we're......even if we can't save every soul, there is a point where a line must be drawn.
The unintended acceleration accidents around here happened when the accelerator was depressed while thinking they were pressing the brake - a panic situation.
I remember watching a guy come shooting through a car wash door and down a ravine - wasn't hurt. He thought he was cramming the brake down - hard!
One snowmobile driver broke a throttle cable and temporarily hooked the brake cable to the throttle to get home (the cables were alike on these older machines). He didn't get out of the parking lot and he smashed into a car - he said it was impossible to prevent no matter how he tried to tell his brain to think differently - wasn't hurt.
So when your brain has it's mind made up, sometime you just have to ride it out.
I agree that the real usefulness of this systems is pretty negligible, ChasChas. I think the automakers like the idea because it gives them a legal leg to stand on in these cases. Unfortunately, the situation you describe -- wherein the driver stands on the accelerator while assuming he/she is on the brake pedal -- won't be remedied by this. The electronic control system can tell if you're pushing on the brake, but it has no way of knowing if you're just confused.
For guys engaged in a stop light "grand prix," a brake-throttle interlock would prevent the ability to rev the engine up in its torque band while taking slack out of the drive train before launching. Yeah, I can already hear the comments of wasting gas, tires, stressing the car, etc., etc., but hey, it's fun and besides, I like to check my reflexes when the stop light changes. But, all kidding aside, all these fixes are crutches for incompetent drivers, and are subject to failures that may leave the hapless driver and car exposed to injury and damage because the expected safety feature (crutch) didn't function. As the old saying goes, you can make anything fool-proof, but not damnfool-proof.
The very first thing that the NHTSA should do is forbid the sale of any car that does not have a positive means of shutting off the engine. That very specificly would not involve any computer in the shutoff process. I am talking about switching off the ignition power and probably the injector power as well.
The very stupidest thing ever done in a car was to have one button for both start and shutoff. IT may be OK for a light, but it is a very poor choice for a vehicle. I have had instances of throttle sticking wide open, and switching off the ignition saved my hide every time. But in a car where the only option was to task the computer to switch off the engine, and the computer deciding thatit had to keep the engine running because you were in motion, would be a disaster in progress.
So I must conclude that either the NHTSA is not thinking very well, or else they have been paid to ignore the situation. Either way, the lack of a positive engine shutoff means is an inherently unsafe condition.
Reminds me of the old saying - Find a way to idiot proof it and all they will do is invent a better idiot...
Cars, and a lot of other stuff in life, are a potentially dangerous object that we have gotten used to and complacent with. And we live in a society where everything is someone elses fault. How long until one of these "throttle cutoff" devices fails on someone traveling on the expressway in high speed rush hour traffic and causes a multicar pile-up? All of these proposals need to be examened with a large dose of pessimism before they are foisted off as the next quick fix.
I still think the problem is there are too many loose nuts behind the wheel.
This device could be hazardous for high performance track driving. It is standard practice to blip the throttle under braking to accomplish downshifting a couple of seconds before corner entry. A decisive turn in under braking rotates the car to quickly line up to the corner apex. Brake release and throttle application transfer weight to the rear wheels and stop the rotation. Without throttle response, a spinout is probable.
Hopefully, if this device is imposed upon us, it will be user selectable, like the ESP (electronic stability program) in my Audis. The ESP inhibits my inputs when going quickly; thankfully it can be turned off for track driving.
Regarding the effect of BTO on race driving, Toyota has sent us this: "If the brake is pressed first, followed by the accel pedal, BTO does not engage. This allows for hill starts...Also, for those double-footed drivers, BTO won't engage because the system can differentiate between intentional accel pedal input and a stuck pedal. If the APPS detects accel pedal movement, it assumes the pedal is not stuck and the driver is intentionally pressing both pedals."
I sure hope you are right that there is a method of turning it off. There are times during maintenance when I will intentionally have one foot on the accelerator and another on the brake. In addition, years ago my parents' car (1980 Buick Century) had some problem where the engine would die if you didn't keep giving it gas. When you stopped at an intersection, you had to keep giving it gas. (The problem was finally determined to be caused by a failure with some useless government mandated equipment on the car.)
Jack, I remember well what you've described here. I had a 1977 Olds Cutlass with the same problem. The problem was the catalytic converter in its early years. Until the vehicle was warmed up, it would balk whenever I stepped on the accelerator. It made for some very exciting turns into oncoming traffic.
Actually, Charles, the culprit in this case was the EGR valve on a 1980 Buick Century. I've known more than one person who bypassed the thing when their cars got old enough to be able to avoid the annual inspections.
It's not really the EGR valve, but it is part of the emissions controls system. After you romp on the gas, or after a long run on the highway the system will hold the idle high for a few seconds to help cool down the catalytic. Back in the days of carburetors there used to be a whole host of valves and solenoids to control coasting, so at least this part of the system has gotten a little simpler.
THis relates to the comment about the big red emergency stop buttons on machines: not only are they a dedicated stop system, but in addition, for all of my controls engineering career, there was a rule that they had to work in spite of any failure of the controls logic. To clarify that, it means that the stop function must have priority above all other functions. OF course, that can be quite inconvenient and even messy, which is why most machines also have "stop" buttons that are not "emergency stop" buttons. MOst of those machines are much less dangerous than cars, so why not assure that there is a means available to shut off a car?
On the other hand, for those drivers unable to differentiate between an accelerator pedal and a brake pedal, perhaps they could be fitted with a twist-grip throttle like a motorcycle has. That might help them remember the difference. Of course, the most effective method would be to remove their driving privaleges permanently the first time that mistake results in an accident. That penalty could help folks pay closer attention to what theyare doing while at the wheel.
William K: Although I'm sure you're joking about a twist-throttle, please note that motorcycles have had a handlebar-mounted engine kill-switch for longer than I've been riding (40-plus years). It's not a bad idea to add one to autos. I'm now teaching my teenager to drive, and I'd LOVE to have one!
As mentioned by others, this should not simply ask the computer to stop the engine, it should directly stop the ignition and/or the fuel feed. How well do you think the NHTSA-proposed system will work if the throttle-control motor becomes seized (yeah, that'll never happen), or if the computer gets a hair across its electronic tuchus?
I like the idea of a kill switch. Last weekend my daughter rented a Toyota and the accelerator seem somewhat strange in that below 60 mph it seem to have somewhat of a mind of its own. At times, it felt was speeding up then all of a sudden slow down. Kind of a strange feeling.
As a matter of fact, I have had a throttle control motor freeze on me, or at least, it stopped controlling and left me at a 70+ MPH "idle". I was able to control the car with the brakes, even though it was a "360" engine. The vehicle was a developmental one, and the control motor assembly was made by a company in Goshen, Indianna. The gearbox locking problem came from a case of pitch-line runout in the gear trains. If I could figure that out, why couldn't anybody else spot the problem?
Those cars did have regular ignition system switches so the racing engine could always be switched off. Nobody would have driven them if that had been under computer control.
The only safe electrical throttle controller that I have seen used a PWM driven solenoid to open the throttle valve, and if the power was switched off, the throttle would snap shut. The designers of that package even used redundant springs to assure that the throttle would close. So reloiable control is possible, but not cheap.
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