Electronic/electric control for accelerator

Does anyone know of a manufacturer that makes electric or electronic controls for the accelerator pedal to control the carb opening, rather than using a cable.
 
Hi Mike / Steve,

I prototyped a 'fly-by-wire' throttle control a while back which used a radio control type servo. The servo was a ball-raced unit with a 5kg pull and very fast acting. Remember that when you crack the chokes by hand, eg blipping the throttle, the revs out of gear climb instantly so the the servo has to be extremely fast.

I used a PIC micro controller, reading an analogue to digital converter that read the pedal position from a potentiometer (variable resistor). Once read, the processor generated a variable pulse width modulated signal that was used to directly drive the servo.

A mock-up was contructed and tested on a rig, but was never fitted to Roy's 500bhp Mk1 GTD. Mainly because we are always busy tinkering with some other bit of the car.

One very important thing to consider when attempting things like this is SAFETY!!.
SAFETY 1st! - SAFETY 2nd!! and even SAFETY 3rd!!!.

With this in mind I incorporated several failsafes including -
1)checking that the choke position, also read via A/D from injection throttle position sensor, matched the desired position, IF NOT, CUT IGNITION!

2)throttle pedal switch and choke closed switch - If foot off throttle, then choke closed switch should also be sensed, if its not within 0.0x seconds, then again CUT IGNITION!

3)are inputs within expected range - i.e. - if the sensor on the throttle pedal fails - make the system fail safe!

etc, etc, etc.

A fully programmable/mapable throttle will allow different drivers to have different setups. Or a softer setup for road use as opposed to track use. Or how about a limit on available throttle for letting 'novice' drivers 'have a go'?

The options go on and on and I know some would/will consider this sacrilege but each to their own I say. We get pleasure in devising / developing the car for mainly track work - who knows - we might even fit it one day!!
grin.gif
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best wishes


ps - one final thought - fit a receiver and a power servo rack and you've got one hell of a radio controlled car!! - anyone fancy a ride??

[ February 28, 2003: Message edited by: Paul Thompson ]
 
Fly by wire is used on some mass produced passenger cars with EFI.

I've not seen any electric system for a carb though.

Have you looked at the hydraulic throttle systems available?
There was a thread on this a while back, and I haven't seen any updates lately. here is the thread:
web page
 

Jim Rosenthal

Supporter
This would be rather complex and if it failed to function as desired the results could be really disastrous. I am not even sure the hydraulic linkage would react fast enough for you to double-clutch as one ought to be able to. Here's a thought, though: instead of the standard free cable, which is usually a skinny little affair, sometimes without a sheath, how about using a sheathed low-friction cable? some of these are available from Teleflex Morse and if you don't bend them too tight, they move as fast as you want. Also, there are 'cables' I have seen where they actually consist of a sheath packed end to end with ballbearings and prelubed. These are very low friction and react quickly with no lag or slack. Whether they are still around or have been superseded by the Teflon ones I don't know.
There are some throttle control devices which are electronic for marine engines, but I don't know if they react quickly enough for a car. They are made by Mathers and I think Teleflex-Morse. Have fun.
 

Howard Jones

Supporter
A cable can be made to work very well but you will need to use the very best low friction type. I did my GTD with a cable about 12Ft long that cost 50USD and my own design linkage. This system has no responce delay whatsoever and uses a holly double spring setup. Iwould note that I am using a 750 doublepumper. This is a area that took me four completely different types of setups before I came up with the one I liked. But the bottom line is You can use a 'morris type' cable, Morris is not the best manufacture as far as friction goes, and have a very smooth throttle with quick responce. Look for your cable at a industrial cable maker, airplains, heavy equipment, that will make it to lenght with your desired ends on the cable. I used rod ends on both ends and would recomend them. Oh and a little longer is better if it is to achieve gentle radius bends in the cable. Also after leaving the sidepod run the cable up the front of the engine instead of back and up between the exaust along side the bellhousing. This is a shorter run and much less heat to deal with. Reverce the direction of pull with a bell crank and you got to basic idea. Take your time with this, the feel of the throttle is very important.

[ March 01, 2003: Message edited by: Howard Jones ]
 

Robert Logan

Defunct Manufactuer - Old RF Company
MoTeC have done a lot of work for Ford Australia (I think) and others (Saburu, I think is one of them) in this fly by wire and the only coments I have herd that are negitave are the level of current that the servo drags to give a quick response. The major car firms throughout the world are working on high voltage circuits (48 volts) and this will be necessary with all these techonological improvements (or are they). I am sorry but I was brought up on the KISS principle and sometimes things go to far.

Best wishes etc,

Robert
 
The new Ford Falcon (Australian BA model) has fly-by-wire throttle control. It is a mass produced car targeted at the average budget car buyer... so availability shouldn't be a problem.

From a safety perspective, I can't imagine that it would have made it to production if ALL the bugs hadn't been fully ironed out.

From a throttle reaction perspective, they are used on a highly acclaimed sports version of this car (+300 HP) with no complaints from the media yet. In fact, the bottom end version of the car won Australian's most prestigious automotive award, with throttle feel being a factor in most reports.

But it is a very new model, so it may not be easy to find just yet. If you are a purist though, you can at least say that its a genuine Ford part
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Fly by wire throttle would appear to be atractive for a paddle shifter (up/down) setup. Could provide throttle blips, etc.
 
The new Ford F150 will have fly by wire and the GM 8L Crate Engine is setup for fly by wire as well. I haven't had the opportunity to look in to other Models too closely, but the throttle cable as we know it is fading away quite quickly from OEM use.

Jim
 

Fran Hall RCR

GT40s Sponsor
All new G.M engines by the end of the next three years will be fly by wire throttle or ETC as its officially named.
I test them all at work!!

[ March 01, 2003: Message edited by: Fran Hall ]
 
Fran,
Of the new systems that you have seen does the motor directly drive the throttle shaft? Are they stepper motors (digital) or servo (analog)? I would guess stepper to keep costs down.

Thanks
Gary
 
The marine electronic throttle controls are too slow for automotive purposes. (Mathers,
Teleflex,Twin Disc, etc.)
Most have a built in shift actuator, and a throttle delay, which won't allow shifts at high RPM's due to the possibility of gear damage. These are servo controlled, and operate at snail speed.

Bill
 

Jim Rosenthal

Supporter
BMW and MB use fly-by-wire. This seems to be to be more compatible with automatic transmissions than manual shift. I would imagine the FBW software can be configured to blip the throttle or at least match revs- Ferrari and Porsche do this on their paddle-shift cars, they may even be using similar software. But like Robert says, there is such a thing as making things too complex.
Howard is on the money about Morse cables; there is a VERY wide variation in quality, durability and degree of friction. The best I have seen are Teleflex Xtreme- they use a splined Teflon-Delrin inner core, and the contact area is reduced AND is very slippery. Like you say, Howard, gentle large-radius bends are key to prevent binding. Longer is better. If I were using this kind of cable, I would try to find a standard length that would work, because it would then be easy to replace. They do have a limited life, they usually go at the ends or where the jacket is near something hot. Greasing them regularly and swapping them end-for-end occasionally helps them live longer- much easier on a car than a boat where you may have to fish the cable through fifteen or twenty feet.
Congrats on your engine startup, Howard, wish we had audio here...it's a snowy wet day in Maryland and it would sure cheer things up.
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The MB fly by wire has proven to be a bit "finnicky",,,, the actuator is mounted directly to the throttle body and controls idle speed, cruise control,traction, and throttle control.

The problem is that heat has a tendancy to eventually cause problems with them,,,,,and replacements are in the 1 thousand dollar & up range.

You can buy ALOT of replacement throttle cables for a grand!
 
Many thanks for all the input. I checked out the hydraulic unit that Alain rercommended and that seems like a good practical alternative at a reasonable cost. I think I will go with that to start with. It would be fun to develope a fly by wire system. I looked at the possibility of using two Selsyn motors, but they are AC units; however, it could be done with a little work.
There appears to be many possibilities and alternatives. Will have to work on it to see what can be done.
 
My e39 BMW M5 has a fly-by-wire throttle, the official reason being that the eight throttle butterflies would make the pedal too heavy. This also allows the traction control and stability control systems to override the driver's inputs (+cruise control is fully electronic).

The e46 M3 also has the system, and the clutchless-manual version does use this to blip the throttle to rev match downshifts.

I participate in two M-car forums and so far noone has reported any problems with the throttle - I can understand people's reservations though!! A manual cable pull which breaks the servo throttle linkage might be an idea... I guess the race-car guys will have a fuel cut off pull already.

Having different throttle maps is cool - the BMW system offers a "sport" map which features earlier response relative to pedal position when you press the sport button.

ciao

Ian
 
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