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February 25th, 2016, 10:08 PM   #11
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KTM accuses Honda of cheating

Quote:
Originally Posted by Dr No View Post
Semantics, but I'd reword that.

The only way the engine presents a signal to the ECU is via the CPS. Which it (supposedly) samples at 200Hz.



Now ignition timing doesn't need 1rpm resolution, nor do most maps nestled in thr ECU, but to suggest a the imprecision of a 200Hz sampling rate can hide 100rpm is stupid.

The main thing is that the sampling rate for the rev limiting loop is 200 Hz. The consequence of that, along with the non-linear way in which it's done, is that the regulation of RPM is a bit rough and that's all the article is saying I think.

How do they actually sense RPM by the way? I'm assuming there... I've worked with closed-loop digital control systems but not in automotive applications.

And what's the CPS?

This part is gobledy goop though:

Quote:
As a result, the ECU isn't sampling every single revolution when the engine is at the rev limit. At 500 RPM, a Moto3 engine is spinning 225 times per second, and if Bom is correct, and the engine speed is being sampled a much less than 200Hz, then the ECU will be having to average out the signal to calculate the engine speed.
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Last edited by Cool Blue; February 25th, 2016 at 11:29 PM.
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February 25th, 2016, 11:24 PM   #12
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500 RPM would be 8.3 times a second...so yeah that's gobeldy gook.
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February 26th, 2016, 12:22 AM   #13
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Quote:
Originally Posted by Cool Blue View Post
The main thing is that the sampling rate for the rev limiting loop is 200 Hz. The consequence of that, along with the non-linear way in which it's done, is that the regulation of RPM is a bit rough and that's all the article is saying I think.

How do they actually sense RPM by the way? I'm assuming there... I've worked with closed-loop digital control systems but not in automotive applications.

And what's the CPS?

This part is gobledy goop though:
CPS = Crank Position Sensor. Hall effect trigger on the crank.
From that you get an rpm and crank position, so you can fire the ignition when you need to; adjust the injector pulse etc.
I suspect that the rpm signal (which is piss easy to measure) is probably separate to in the 200Hz sampling channel. The ignition and fueling maps, which will depend on the 200Hz rate, don't really need a resolution of 1 rpm. No use, well, tedious/laborious/expensive in the extreme to create that level of accuracy. So if they are a little sketchy at high rpm, it's not really going to affect much.
What does matter is the rate of change of rpm. If you can accurately model that, you can predict when to start pulling spark out and winding down the fueling for a soft limiter. Do this gear by gear and you'll be getting there.

(Edit: err, we're pretty much saying the same thing )
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February 26th, 2016, 01:06 AM   #14
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Ah ok, thanks. I figured it might be a proximity sensor on the crank that you were referring to but I wasn't sure. In that case, for sure it will be converted to RPM on a different channel and at a much higher sampling rate. They might even have some silicone real estate allocated to a hardware counter to do that asynchronously and update a register every pulse.
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March 11th, 2016, 12:31 PM   #15
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So here it is CONFIRMED!!! No Breach of Moto3 Rev Limits by Honda in 2015
https://motomatters.com/news/2016/03...reach_of_.html

Honda out engineer KTM as suspected.
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March 11th, 2016, 12:39 PM   #16
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Quote:
Originally Posted by evo9 View Post
So here it is CONFIRMED!!! No Breach of Moto3 Rev Limits by Honda in 2015
https://motomatters.com/news/2016/03...reach_of_.html

Honda out engineer KTM as suspected.
NO breach?


"...although there had been overshoots of the rev limit, these were very small and very brief."

"The time it took between the moment the ECU identified that the rev limit had been breached and the point at which it started to cut the ignition was long enough for their to be a very brief overrun of the allowed rev limit. These were, however, only "modest and temporary"."

13,501=breach=cheating.

'CONFIRMED'
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March 11th, 2016, 01:06 PM   #17
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Quote:
Originally Posted by Jumkie View Post
NO breach?


"...although there had been overshoots of the rev limit, these were very small and very brief."

"The time it took between the moment the ECU identified that the rev limit had been breached and the point at which it started to cut the ignition was long enough for their to be a very brief overrun of the allowed rev limit. These were, however, only "modest and temporary"."

13,501=breach=cheating.

'CONFIRMED'

Jum I work in the automotive industry. I currently have a fleet of MB Sprinters. A few years back, corp said to cap top speed @ 65 MPH. Guess what! They all peak at 66 MPH then stabilize at 65 MPH. When I was doing this back in the 90's on early electronic class 8 trucks, the results were the same.
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March 11th, 2016, 01:07 PM   #18
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Quote:
Originally Posted by Jumkie View Post
NO breach?


"...although there had been overshoots of the rev limit, these were very small and very brief."

"The time it took between the moment the ECU identified that the rev limit had been breached and the point at which it started to cut the ignition was long enough for their to be a very brief overrun of the allowed rev limit. These were, however, only "modest and temporary"."

13,501=breach=cheating.

'CONFIRMED'

So this is where compared to the rest of the paddock?
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March 11th, 2016, 01:25 PM   #19
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Quote:
Originally Posted by evo9 View Post
Jum I work in the automotive industry. I currently have a fleet of MB Sprinters. A few years back, corp said to cap top speed @ 65 MPH. Guess what! They all peak at 66 MPH then stabilize at 65 MPH. When I was doing this back in the 90's on early electronic class 8 trucks, the results were the same.
I'm just clowning around bro. But technically, 1 rev over is breach.

I remember there was also a big snafu with the Yamaha R6 claims of revs, turned into a big brouhaha.
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March 11th, 2016, 01:29 PM   #20
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Quote:
Originally Posted by Cool Blue View Post
So this is where compared to the rest of the paddock?
Fuck if i know, good question. However, the bloke said it was "modest and temporary", I guess that makes it ok? So....make of that what you will. Kinda reminds me of when I was a younger buck and talked a honey into a little action, I told her, just the tip honey, as in like modest and temporary.
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