Electronic Throttle Rules

[Greg H]

Reading over the rules FAQ I came across this one.
Throttle Body for Traction Control (http://www.formulasae.org/forums/formula/dispatch.cgi/rules/docProfile/100085/d20051109192815/No/3.5.4.3%20TB%20for%20Traction%20Control)

In this case, the team wants to have a second throttle body that allows less air to pass through for traction control purposes. Since the air can only be reduced electronically, they approved it for safety.

Using the logic that electronic throttle control is only outlawed for safety reasons, it should be possible for a dual system to work completely electronically. All a driver would need to do is depress a lever with their heel to open the mechanical TB to full and use the actual pedal to do the throttling electronically. Should the electronic TB fail, all a driver would need to do is raise his heel to shut off all air to the engine.

Basically, I'm saying that this is not a violation of the intent of the rule if the rule is only in there for safety reasons. If the intent was to prevent an advantageous electronic TB over a mechanical one, than it would be in violation. Any thoughts?

[Greg H]

Reading over the rules FAQ I came across this one.
Throttle Body for Traction Control (http://www.formulasae.org/forums/formula/dispatch.cgi/rules/docProfile/100085/d20051109192815/No/3.5.4.3%20TB%20for%20Traction%20Control)

In this case, the team wants to have a second throttle body that allows less air to pass through for traction control purposes. Since the air can only be reduced electronically, they approved it for safety.

Using the logic that electronic throttle control is only outlawed for safety reasons, it should be possible for a dual system to work completely electronically. All a driver would need to do is depress a lever with their heel to open the mechanical TB to full and use the actual pedal to do the throttling electronically. Should the electronic TB fail, all a driver would need to do is raise his heel to shut off all air to the engine.

Basically, I'm saying that this is not a violation of the intent of the rule if the rule is only in there for safety reasons. If the intent was to prevent an advantageous electronic TB over a mechanical one, than it would be in violation. Any thoughts?

[HenningO]

I think it's a good idea, but something that probably could get banned pretty quick if someone managed to work properly.

The question, from a safety point of view, is wheter a driver who suddenly realizes that the throttle has jammed remembers to "lift his heel" before it's too late?

I wouldn't say it's a problem, but I can imagine the judges might do it.

I would suggest a design where the first 25% of the pedal stroke operates the mechanical throttle and the last 75% of the stroke operates the electronic throttle. So if the electronic one fails, the car would still be driveable.

[HenningO]

But on the other hand, it seems like a solution like that wouldn't comply with this:

http://www.formulasae.org/forums/formula/dispatch.cgi/r...629/No/3.5.4.2%20ETC (http://www.formulasae.org/forums/formula/dispatch.cgi/rules/docProfile/100083/d20051109183629/No/3.5.4.2%20ETC)

[Michael Royce]

Henning O has it correct with his second posting.

In the spirit of allowing teams as much design freedom as possible, we tried allowing ETC a handful of years ago. However, based on what we, in the industry know about what it takes in terms of redundancy, etc. to ensure safe systems, we had to call it off after a couple of years. Even with only a couple of teams wanting to use ETC, the effort we required of our industry ETC experts to review and approve the designs BEFORE the events, was just too much. Checking "simple" mechanical (cable or rod) systems is tough enough.

I cannot see a rules change on this particular area. So I don't think it is worth people spending a great deal more time on the subject.

However, it is gratifying to know that some people are reading the FAQ's posted on the official SAE website.

[Ben Beacock]

In the reponse to the original request (the two throttle bodies in series) it was noted that "car must be equipped with a carburetor or throttle body" and that it infers a singular item. If I have two (or more) throttle bodies, is the car not still "equipped with a carburetor or throttle body"? If there are multiple airbags in a car, I could say that it is "equipped with an airbag", meaning that it has at least one.

If the rules say that it "must be equipped with one carburetor or throttle body" it would be definitive.

I don't mean to poke holes in anything, I just bring it up for discussion since I find the 'legalese' of motorsports very fascinating.

[markocosic]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">The question, from a safety point of view, is wheter a driver who suddenly realizes that the throttle has jammed remembers to "lift his heel" before it's too late? </div></BLOCKQUOTE>

One could argue that "drive by wire" is fine but "stop by wire" or "steer by wire" are not.

Assuming your driver isn't stupid and that you have installed a killswitch, the design of the throttle doesn't matter - if it sticks, you kill battery power/ECU power/coil power/fuel pump power/fuel injector power/alternator feed(by pressing one dirty great button on the steering wheel) and all is well. Doesn't really matter who the driver is if the brakes or steering fail. (bar downshifting/picking a friendly bit of hay to crash into...)

Running that past the rules committee in itself might not be too bad (it appears to meet the intent of the rule) BUT I suspect their hands are tied for other reasons - INSURERS!

There's a tendency (especially in the USA; this is the land where the barman is liable if he serves you a beer assuming you're not stupid enough to drive afterwards and you then kill somebody whilst driving home drunk) to assume everybody is stupid when calculating risks/apportioning blame. IF something were to go wrong, "we've banned all by-wire controls for safety reasons" is a way to show you've taken all reasonable steps to prevent injury. "We've mandated killswitches and ASSUMED that our drivers aren't stupid" wouldn't go down so well in court - that assumption means you're suddenly liable, and if I were in their (the rules committee) shoes I wouldn't want to take that risk - would you?

[Marshall Grice]

Obviously parallel TB's should be illegal, but how can two TB's in series be allowed in one case(ETC only reduces incoming air) and not in another(mechanical TB only closes when foot is lifted, ETC does everything else)? Seems obvious that you just say the ETC is for traction control and that you've just implimented an "foot adjustable" algorithm.

[Akos]

You can always build an electronic version of the governor found on most briggs and stratton engined lawn mowers. This way you don't need two throttle bodies. I think it will still satisfy the intent of the rules when it comes to having a mechanical way of closing the throttle.

This way you still have a mechanical throttle for most of the operation with the electronics only for tc purposes.

My $0.02

[Bryan Hagenauer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by markocosic:
Assuming your driver isn't stupid and that you have installed a killswitch, the design of the throttle doesn't matter </div></BLOCKQUOTE>

Have you never seen a stuck throttle occur?

Anyone who was at Detriot in 2004 did, and knows that the killswitch thought process may be overcome by the get-the-hell-out thought process. Luckily in that case the car was stopped by something at low speed. I've also seen pictures of scenes posted here due to stuck throttles.

You can call a driver stupid all you want, but that's not going to protect him and others from injury.

[markocosic]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Have you never seen a stuck throttle occur?
</div></BLOCKQUOTE>

Yes - personal experience (albeit on two wheels) that I don't wish to repeat!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Anyone who was at Detriot in 2004 did, and knows that the killswitch thought process may be overcome by the get-the-hell-out thought process. </div></BLOCKQUOTE>

Wasn't there. :-(

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You can call a driver stupid all you want, but that's not going to protect him and others from injury. </div></BLOCKQUOTE>

I'm not so sure - would say it depends a lot on what you implement?

After the stuck throttle experience even my road-car got a "machine tool" style killswitch (green to start and latch the power relays; so much as breathe on a big red switch to drop out the power relays; green lights up with engine off, red glows gently with engine on). Worked a treat the last time it ended up on its roof and I'd say if there were a dirty great button on the steering wheel marked 'stop' a driver would hit it pretty quickly!

Most FSAE cars seem to look something like this one:
http://web.mit.edu/cosic/www/FSAE-UK-2005/target79.html
(with the button to start them and a little switch to stop them) I'd agree with you there in that most drivers wouldn't be too keen to fumble about for a pissant little toggle switch whilst trying to control the machine.

[Greg H]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Marshall Grice:
Seems obvious that you just say the ETC is for traction control and that you've just implimented an "foot adjustable" algorithm. </div></BLOCKQUOTE>
Right on Marshall.

About stuck throttle:
About an hour after I wrote this first post we went out driving last year's car. The throttle was stuck wide open (due to a jammed second return spring meant to prevent such a thing http://fsae.com/groupee_common/emoticons/icon_smile.gif ) and the first thing that the driver did was shut off the kill switch. I agree that not everyone will instantly make that decision, that's why I suggested this device in the first place. It's a means to put a mechanical safeguard on an electrical system that should make it feasible for teams to run "throttle by wire" in a safe manner.