electronic throttle
in [Toyota]
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From: Bill Putney on 7 Mar 2010 17:18 jim beam wrote: > 2. why would you pump the pedal repeatedly when you're trying to stop > the vehicle? That used to be taught as the proper way to brake in certain situations. Indeed - if it was not a common conception in may people's minds driving today, the word in the context of brakes wouldn't be as well known - by that I mean, if you used the term "pumping your brakes", people don't say to you "What does that mean?" Everyone knows the term because it is ingrained by having been taught as a proper technique (again, in certain situations). Perhaps it is considered by some to be obsolete, maybe because of ABS - but there are cars built today without ABS. ALSO - imagine a person who is suddenly faced with runaway acceleration - I can imagine it being a natural instinct to push the brakes and be surprised that they aren't working to well against the power of the engine, and to take another stab at it (literally) - not realizing that they just used up whatever hope they may have had in the brakes overcoming the power of the engine in having done so. Think of it as being similar to why police often finding shooting victims with a bullet hole in their hands - why? Because it is the natural instinct for a person to hold their hands up in front of their face if someone points a gun at their face. Does it make any sense to a rational person to think that that would help the situation? No. But the mind does "stupid" things in panic situations. Things that Data or Mr. Spock wouldn't understand, but that make sense from a human standpoint. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
From: clare on 7 Mar 2010 17:22 On Sat, 06 Mar 2010 17:08:03 -0800, jim beam <me(a)privacy.net> wrote: >On 03/06/2010 04:59 PM, clare(a)snyder.on.ca wrote: >> On Sat, 06 Mar 2010 12:43:14 -0800, jim beam<me(a)privacy.net> wrote: >> >>> On 03/06/2010 09:41 AM, Jim Warman wrote: >>>> The cross posting sucks.. but you guys seem to like it.... >>>> >>>> Toyota is having trouble... Ford isn't (I'm reading this in a Ford NG and I >>>> work at a Ford dealer). >>>> >>>> Drive by wire throttle is a natural progression (if you can't see where the >>>> future of the automobile is going - I feel sorry for you). It allows for >>>> precise (hopefully) control of any electronic stability features, It allows >>>> for torque limiting when appropirate... reducing the need for other traction >>>> control measures (such as active brake booster application) when >>>> necessary... >>>> >>>> Fords system relies on redundancy... I'm not a Toyota tech so I can't tell >>>> you what they do... Fords system has three inputs..(one of them is inversely >>>> proportional). If the inputs aren't "coherent", the car will remain at >>>> idle... >>> >>> three inputs from the throttle pedal position sensor? >>> >> >> 3 inputs are an absolute necessity for true"fail-safe" systems. If 2 >> inputs dissagree, what do you know, other than that you have a >> problem. With 3 inputs, if 2 agree and one dissagrees, you have a >> pretty good idea which input is wrong. > >yeah, i get that, but where are the three inputs? does any vehicle have >more than one pedal position sensor? > One throttle position sensor of the simplest design (a simple potentiometer) can provide 2 signals - one the inverse of the other. The third input could be as simple as a closed throttle ot WOT sensor switch. If the Throttle position and the _throttle position switch dissagreed about whether the throttle was open or closed (ie - the sensor was open or shorted) the idle position switch would confirm if in fact the throttle was at idle. (or the WOT could confirm if it was at WOT) The idle position switch is the simplest because when you first start the engine the computer could poll the position sensor, and if both sides of the pot did not indicate closed throttle, the switch could be asked for it's "vote". That is your "3 inputs" in it's simplest form. > >>> >>> >>>> >>>> Have we seen problems with Fords drive by wire? A very few, but yes.... No >>>> unintended accelerations have been (AFAIK) documented. >>>> >>>> >>>> "Jeff Strickland"<crwlrjeff(a)yahoo.com> wrote in message >>>> news:hmu1u8$uus$1(a)news.eternal-september.org... >>>>> >>>>> "jim beam"<me(a)privacy.net> wrote in message >>>>> news:fvudnV-hwr-Z6A_WnZ2dnUVZ_rednZ2d(a)speakeasy.net... >>>>>> if you buy all this fear-mongering idiocy that electronic throttle is a >>>>>> problem, and that brakes, transmissions and ignition kill switches can >>>>>> all simultaneously fail causing a driver to lose control, it might be >>>>>> worth auto manufacturers of all stripes to adopt a slightly different >>>>>> implementation of electronic throttle [e.t.] - if not for mechanical >>>>>> reasons, but to shut the idiots up. >>>>>> >>>>>> first, lets understand e.t. functionality: >>>>>> >>>>>> 1. open the throttle when demanded >>>>>> 2. close throttle when demanded >>>>>> 3. allow "demand" to account for additional requirements like >>>>>> a. de-throttle on shifting for automatics, >>>>>> b. throttle appropriate to load at high demand [eg. full throttle at low >>>>>> rpms can choke an engine and significantly reduce output - thus >>>>>> de-throttle until revs support full open] >>>>> >>>>> >>>>> The functionality is even easier than that -- open the throttle plate when >>>>> the gas pedal is pressed and close the throttle plate when the gas pedal >>>>> is released. You can get bogged down in semantics if you want, but the >>>>> functiionality is really that simple Go when the pedal is pressed and stop >>>>> going when the pedal is released. At the end of the day, anything else is >>>>> a variation on pushing the pedal down or releasing the pedal so that it >>>>> comes back up. >>>>> >>>>> When or why one might press or release the pedal has no bearing on the >>>>> discussion. The only thing that matters is the expecation that the car >>>>> goes faster when the pedal is pressed and stops going faster when the >>>>> pedal is held at a mid-point, and slows when the pedal is released. >>>>> >>>>> When the throttle control system does those things, then it is doing its >>>>> job. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>
From: clare on 7 Mar 2010 17:26 On Sat, 06 Mar 2010 23:26:47 -0500, Bill Putney <bptn(a)kinez.net> wrote: >jim beam wrote: >> On 03/06/2010 11:48 AM, Ed Pawlowski wrote: > >>> ...Emergencies do happen and a driver should be competent enough >>> to shift into neutral. >> >> or stomp the brakes - which are three times more powerful than the >> engine,... > >I don't necessarily disagree with the rest of your post, but that part >of your post is definitely incorrect. Have you ever played with your >power brakes while simultaneously pressing the accelerator? Anything >more than one or two initial stabs at the brakes depletes the vacuum >stored in the booster, and with even slight power simultaneously being >demanded of the engine, the vacuum is not enough to directly power the >brakes, much less re-charge the vacuum in the booster. > >People don't believe that, but try it on your car: On a deserted road at >highway speed, stab the brake pedal a couple of times while holding the >gas pedal down a little bit to load the engine slightly (this works >anywhere from slight to WOT throttle). I guarantee you (unless your >brake booster gets its vacuum from something besides the intake vacuum - >like a separate electric motor-driven vacuum pump) that after two or >more stabs at the brake pedal, the braking power will be extremely low - >so low that the engine will have no trouble overpowering the brakes. No >vacuum in the booster essentially equals no brakes. > >Also, once the booster is depleted of vacuum during that experiment, the >vacuum charge in the booster will remain depleted until a second or so >after the throttle is released - IOW - deplete it and continue applying >the throttle (again - doesn't have to be anywhere near WOT) for several >seconds. Every once in a while, while still applying the throttle, try >the brakes again. You will not have any effective braking until *after* >you release the throttle. > >I urge anyone who doesn't believe what I claim above to try it before >commenting. Bill is 100% correct. And as I stated before - IF you are going to attempt to stop a runnaway car with the brakes, make sure you attempt to STOP it, not control it. You have ONE CHANCE. Brake hard - and don't second guess yourself and rekease the brake. He who hesitiates HAS LOST.
From: fred on 7 Mar 2010 17:33 bjn <elvis(a)example.com> wrote in news:hii7p5d6ga5d7ab1s9ok7krqqla85cdki1(a)4ax.com: > On Sat, 06 Mar 2010 10:38:19 -0500, Bill Putney <bptn(a)kinez.net> > wrote: > >>jim beam wrote: >>> if you buy all this fear-mongering idiocy that electronic throttle >>> is a problem, and that brakes, transmissions and ignition kill >>> switches can all simultaneously fail causing a driver to lose >>> control, it might be worth auto manufacturers of all stripes to >>> adopt a slightly different implementation of electronic throttle >>> [e.t.] - if not for mechanical reasons, but to shut the idiots up... >> >>The lawyers, politicians, and news media can convince the public of >>the impossible (failure even a totally fail safe system) any time they >>decide to do it depending on political or monetary motivation. IOW - >>the people and companies who do a good job of designing are going to >>get punished anyway (unless they know how to play the game in a >>corrupt system). There are people in our society whose life goal is >>to make sure that that happens. > > > The problem is that now lawyers, politicians and news media are > driving (no pun intended) solution. The way I see them talking, cars > will wind up with a fail-safe throttle that is more fail-safe than the > controls of a jumbo passenger jet. > I think you'll find that commercial and private airliners go in the exact opposite direction.
From: fred on 7 Mar 2010 17:33
jim beam <me(a)privacy.net> wrote in news:fvudnV-hwr-Z6A_WnZ2dnUVZ_rednZ2d(a)speakeasy.net: > if you buy all this fear-mongering idiocy that electronic throttle is > a problem, and that brakes, transmissions and ignition kill switches > can all simultaneously fail causing a driver to lose control, it might > be worth auto manufacturers of all stripes to adopt a slightly > different implementation of electronic throttle [e.t.] - if not for > mechanical reasons, but to shut the idiots up. > > first, lets understand e.t. functionality: > > 1. open the throttle when demanded > 2. close throttle when demanded > 3. allow "demand" to account for additional requirements like > a. de-throttle on shifting for automatics, > b. throttle appropriate to load at high demand [eg. full throttle > at > low rpms can choke an engine and significantly reduce output - thus > de-throttle until revs support full open] > > if we analyze the above [which is not exhaustive, but representative], > we find that in almost all situations, an e.t. needs to be more closed > than demanded, but seldom, if ever, more open. thus the "solution" to > the fear-mongering might be to have the throttle opened mechanically - > i.e. old fashioned cable linkage, but have the computer control a > closer device. thus, all the above can be implemented electronically, > but whenever the driver lifts their foot, the mechanical closure > cannot be over-ridden. and the throttle can never be more open than > the mechanical throttle command. > > this would not only address the "potential" for a runaway failure > [although how exactly a computer is supposed to fail such that it > won't switch off, disables brakes, disables transmission select, but > still runs its injection code is something i have never seen > explained, even by the most strident "but it must be the electronics" > crowd], but it would also remove the single most annoying thing i have > ever experienced in any vehicle driving experience: chevy's idiot > idea that they need a multi-second delay between foot pedal movement > and e.t movement. anyone that's ever tried to drive a chevy hhr on a > winding mountain road knows what i mean. > Chevrolet's not unique in that regard. The persistant occurance of cars with paddle shifters whose operation have no co-relation to the actual shifting of gears is more of 6the same. At a glance it sounds to me like we're not actually hearing from people who *know* what the problem is yet. Merely seems to be the background noise of the press et all. |