fly by wire throttle

Free Open Source Firmware project discussion forum. Post your Free Open Source firmware projects here!
Post Reply
johnd
DIP8 - Involved
Posts: 23
Joined: Tue Jun 24, 2008 8:21 pm

fly by wire throttle

Post by johnd »

HI, Iam new to this forum is anybody working on a flyby wire throttle controller --and if not why not --nearly all cars use them now and all cars will have them without exception in next 2-4years
with correct control of them you can do lots of other things apart from just follow what the throttle pedal tells it to.
like boost control, traction control, cruise control ,can be linked to gear box for better shifting ,especially down shifting etc etc
my field is using ecus and have fitted most of the leading makes over last 15years--not making them ,so i understand from the users end what I want from an ecu
Last edited by johnd on Tue Jun 24, 2008 9:00 pm, edited 1 time in total.
User avatar
Fred
Moderator
Posts: 15431
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: fly by wire throttle

Post by Fred »

I'm interested in some sort of throttle plate control, but at the least it will be labelled with "to be used with dual butterflies only" or similar. It would be very nice to obtain a more linear throttle response electronically, and of course it is easily the best way to do traction control by a country mile etc etc.

No one is working on one yet, as you have to have the cake before you can spread the icing on it ;-)

I hope that answers your question :-)

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
johnd
DIP8 - Involved
Posts: 23
Joined: Tue Jun 24, 2008 8:21 pm

Re: fly by wire throttle

Post by johnd »

thanks for the reply
It is a myth about fly -by wire that they can do silly things --providing you use same protocols as std ecus --two tps sennsors wired independantly on the edal and measuring voltage in opposite directions and two on the motorised unit --if they dont agree on either the pedal end or the throttle itself ,then a fault is logged and the power is cut to throttle motor --it then shuts under the spring tension in the motor unit .
User avatar
Fred
Moderator
Posts: 15431
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: fly by wire throttle

Post by Fred »

johnd wrote:It is a myth about fly -by wire that they can do silly things
I've been writing software for nearly 20 years and I can tell you emphatically that silly things can always happen. That code that is supposed to handle a failure could behave wrongly because of some third party memory corruption from a bad pointer in a random part of the code etc. So, liability IS an issue, but provided that it is for a specific purpose and someone misuses it according to the documentation etc then it shouldn't be an issue anyway. Certainly when I'm home in little old NZ, no American can sue me, so the chances of being sued at all are slim to none.

But no, not a myth. All software can always contain bugs, and I don't have a testing team to ensure that it doesn't unlike OEMs and motec etc etc etc.

That's not to say you can't patch my released system and build your own with it included though :-)

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
johnd
DIP8 - Involved
Posts: 23
Joined: Tue Jun 24, 2008 8:21 pm

Re: fly by wire throttle

Post by johnd »

I have been confusing std eucs for some years now fitted with FBW units ,even to the point of fitting stand alones in piggy back with std ecu ,but with most of other parts of std ecu disconnected ,and the worst i have seen a FBW unit do is to be sluggish or a time delay in opening ,or not open to desired value ,never ever manged to get one stick fully open -- yes I have had them close down and not open again --but never fail in a dangerous way --but i take your point and understand what you are saying .
As i have said before I am not an elctronics guru --but if you are telling me that its not possible to get a comparitor chip to be consisitant when it only has to look at 2 pairs of what are basically tps sensors then I would be worried about the coding or quality of the senssors used .I know from trying to back engineer that the OE units will throw a wobbly if the sensors are not with 0.1v of each other (and impedance/resistance must be very close as well),
so if you even get a dirty connector on std unit it can go fault and just close down,but never do the nasty thing.the std ecu also precheck vlaues of these pots and wiring every time you turn the car on and recalibrate themselves on every start-up.
most modern eus do the smae with the map sensors -and std tps -you turn the car off but ecu stays partially turned on for up to 2 mins to check its claibrations --ie atmospheric pressure +tps zero point
User avatar
Fred
Moderator
Posts: 15431
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: fly by wire throttle

Post by Fred »

I'd like to say "my code is flawless" but I'd be an arrogant fool to say that :-)

Reality is that bugs are a real possibility, and while the chances of one affecting such a system in a dangerous way are slim to none if well designed and tested, it could still happen. It only takes one wrong pointer variable to cause random memory corruption.

On the Lexus V8 you will find a 70mm throttle with a stepper motor and second plate. It is used for traction control in OEM configuration but like modern bikes, standard mechanical throttles are in series with it. In this way you have a double fail safe if you like. I may one day reassemble my stepper and try to use that system on my vehicle. I think it is a winner for traction control (Which i desperately need) so I'm keen to try it. But that is a while down the line for sure.

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
User avatar
jbelanger
LQFP144 - On Top Of The Game
Posts: 387
Joined: Sat Feb 23, 2008 8:58 pm
Contact:

Re: fly by wire throttle

Post by jbelanger »

Even with redundant sensors, if the code commands WOT, then the throttle will be fully open and if it's due to a code error or a glitch or whatever and not the desired effect, then you're screwed.

As Fred says, creating perfect code is very difficult and time consuming and proving that it is perfect is almost impossible. There are ways to minimize the consequences of unwanted behaviour but all this is not trivial. So the option of the dual throttle remains the safest but it will not allow for cruise control or blipping the throttle on downshifts (and this last one would also require transmission control).

Jean
User avatar
Fred
Moderator
Posts: 15431
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: fly by wire throttle

Post by Fred »

jbelanger wrote:So the option of the dual throttle remains the safest but it will not allow for cruise control or blipping the throttle on downshifts (and this last one would also require transmission control).
The cruise control can be done with an oversized idle valve (the bosch ones are quite big).

As for blipping, I'm not sure I want to have any part in taking the fun out of driving! YOU should drive your car, not a PC, and blipping properly takes a little bit of skill. I'd like to be able to demonstrate that, and I'd like those that can't do it to not be able to. If it's auto/SVG/etc then sure, but I think thats a WEEEEE bit outside our scope here ;-)

I've driven one of those flash late model BMWs with the SVG box (solenoid manual with solenoid clutch and ecu control) and it SUCKED, hard driving was brutally harsh and not overly fast and slow driving was "learner smooth" (read rough!). It needed feedback or something. The downshift blipping was cool though, but as I said, I prefer to do it myself DIYefi ;-) lol.

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
GrowlingandBiffo
QFP80 - Contributor
Posts: 56
Joined: Sat Apr 26, 2008 7:42 am

Re: fly by wire throttle

Post by GrowlingandBiffo »

Are any new cars still made with throttle cables?

The only Fly by Wire safety issues we can recall are Volvo, in the US of A when their cars suddenly took off and hit something but this was traced to pilot error.

If you try and "blip" the throttle, when stationary, in a modern lorry it will not rev very high. This stops bored and stoopid drivers from pretending that they are racing..

Perhaps all ecu's will have this as an option so you can let the kidz borrow the car, or will it be std to reduce emissions, and save fuel.

Race cars are faster with Fly by Wire, which is why they stated to use them..

http://www.vems.hu/wiki/index.php?page= ... reThrottle
User avatar
Fred
Moderator
Posts: 15431
Joined: Tue Jan 15, 2008 2:31 pm
Location: Home sweet home!
Contact:

Re: fly by wire throttle

Post by Fred »

GrowlingandBiffo wrote:If you try and "blip" the throttle, when stationary, in a modern lorry it will not rev very high. This stops bored and stoopid drivers from pretending that they are racing...
Interesting, but no good for a mean sideways launch now is it ;-)
Perhaps all ecu's will have this as an option so you can let the kidz borrow the car
Good point, valet mode with this would be perfect!

From the VEMS "Another ECU LOL" page a good link on autospeed : http://autospeed.com/cms/article.html?&A=1025

Fred.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!
Post Reply