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Combined G Anomaly?

 
Old 04-13-2019, 09:27 PM
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Beantown Kman
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Default Combined G Anomaly?

I just returned from an event at VIR. While comparing data from the event between two different drivers in similar cars with similar setups (but one is on slicks and the other is on R compounds) I saw a curious pattern while looking at combined G. One driver's data shows these jagged traces. Do any of you have any thoughts as to what might explain this?

FYI this is through Turn 1 at VIR.


Combined G through Turn 1 at VIR

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Old 04-13-2019, 11:28 PM
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GPS accelerometers vs actual?
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Old 04-14-2019, 12:54 AM
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Smoothing setting?
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Old 04-14-2019, 09:35 AM
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Both.
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Old 04-14-2019, 10:58 AM
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Originally Posted by Matt Romanowski View Post
GPS accelerometers vs actual?
They both appear to be using the same CombG math channel that uses GPS Lat and Lon Accel. How do you choose the "actual" accelerometers? Is one preferred over the other?

Originally Posted by Der ABT View Post
Smoothing setting?
Where do I find this?
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Old 04-14-2019, 09:27 PM
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Originally Posted by Beantown Kman View Post
They both appear to be using the same CombG math channel that uses GPS Lat and Lon Accel. How do you choose the "actual" accelerometers? Is one preferred over the other?

Hard to say, Looks to me like GPS derived, versus accelerometer derived. But you say they're both the same.

Where do I find this?
See attached pic. Click on the channel properties by clicking on the channel, then filtering.
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Old 04-15-2019, 09:41 AM
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Thanks Peter!
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Old 04-15-2019, 03:07 PM
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Beat me to it. Thanks peter
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Old 04-15-2019, 03:09 PM
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Originally Posted by ProCoach View Post
See attached pic. Click on the channel properties by clicking on the channel, then filtering
Be willing to bet the smoothing (filtering) value is not the same for each test.
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Old 04-15-2019, 09:37 PM
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Here's how to check the match channels themselves A and B are where to click so you can check. Look at C to find what channels were used and D to see if there is a filter on the math channel.
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Old 04-17-2019, 08:51 PM
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I checked the Combined G math channels for both cars/tests. They are identical with respect to all of their settings and formulas.

The formula for the math channels used is: sqrt(GPS_LatAcc^2+GPS_LonAcc^2)

Any other thoughts or suggestions?
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Old 04-17-2019, 08:55 PM
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Originally Posted by Beantown Kman View Post
I checked the Combined G math channels for both cars/tests. They are identical with respect to all of their settings and formulas.

The formula for the math channels used is: sqrt(GPS_LatAcc^2+GPS_LonAcc^2)

Any other thoughts or suggestions?
That formula is incorrect. Your syntax is not right.

Should be sqrt((GPS_LatAcc^2)+(GPS_LonAcc^2))
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Old 04-17-2019, 09:28 PM
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Originally Posted by Beantown Kman View Post
I checked the Combined G math channels for both cars/tests. They are identical with respect to all of their settings and formulas.

The formula for the math channels used is: sqrt(GPS_LatAcc^2+GPS_LonAcc^2)

Any other thoughts or suggestions?
What are the two loggers? Is the GPS set at the same logging rate?


Originally Posted by ProCoach View Post
That formula is incorrect. Your syntax is not right.

Should be sqrt((GPS_LatAcc^2)+(GPS_LonAcc^2))
His formula is fine and the syntax is correct. PEMDAS.
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Old 04-18-2019, 08:23 AM
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[QUOTE=Matt Romanowski;15781406]What are the two loggers? Is the GPS set at the same logging rate?

The logger with the smoother traces is a AiM MXL2. The logger with the more jagged line is a SoloDL. I do not know how to check the "logging rate" of the two devices.

Am I reading too much into this?? When comparing CombinedG one stood out to me as being so irregular that it made me question what caused it to look like that. Is it possible the logger itself is not mounted firmly enough in the car?
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Old 04-18-2019, 08:29 AM
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[QUOTE=Beantown Kman;15782113]
Originally Posted by Matt Romanowski View Post
What are the two loggers? Is the GPS set at the same logging rate?

The logger with the smoother traces is a AiM MXL2. The logger with the more jagged line is a SoloDL. I do not know how to check the "logging rate" of the two devices.

Am I reading too much into this?? When comparing CombinedG one stood out to me as being so irregular that it made me question what caused it to look like that. Is it possible the logger itself is not mounted firmly enough in the car?
The logging rate of the logger is in the setup. Unless someone changed it, they should both be 10 Hz.

The smooth one is using more of the available grip all the time. That is really what you want to know.

It could be mounting. I would look at the whole lap and other test sessions to see if it was a problem before I went about trying to fix it.
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