G meter not moving at all

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froggy47
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G meter not moving at all

Post by froggy47 »

Testing still,

Moto X, Dual160, generic obd,

1) G meter pegged dead center never moves a hair

2) What triggers the upper left display of straight speed & curve speed? Those are working.

Thanks!
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2004 Corvette Z06
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Harry
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Re: G meter not moving at all

Post by Harry »

1) Is this in an overlaid video? In case everything else is fine, I assume acceleration has been reset while driving or calibration has not been done while in the pits. Usually this works automatically, but missing acceleration can happen in one of the above situations. To fix after the fact, select the lap from Lap List and press the Recalculate button. Select Acceleration and adjust the calculated (not measured) lateral acceleration as required. Once back in Lap Details, Revert to the raw video and run the overlay again.
2) These are max and min speeds achieved while driving. Either GPS or OBD based.

- Harry
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froggy47
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Re: G meter not moving at all

Post by froggy47 »

Harry wrote:1) Is this in an overlaid video? In case everything else is fine, I assume acceleration has been reset while driving or calibration has not been done while in the pits. Usually this works automatically, but missing acceleration can happen in one of the above situations. To fix after the fact, select the lap from Lap List and press the Recalculate button. Select Acceleration and adjust the calculated (not measured) lateral acceleration as required. Once back in Lap Details, Revert to the raw video and run the overlay again.
2) These are max and min speeds achieved while driving. Either GPS or OBD based.

- Harry
1) I used +calibrate, +accelerate +brake to search the forum, nothing.

For number 2) it seemed more like max speed straight and max speed on curves, one or 2 min speeds posted

but

they appear 10 times on one lap at different speeds so there is more to this than just one max and one min speed. Some other parameter/sensor is triggering when to display (straight & curve) so I am just trying to understand what makes HLT "decide" this moment of the lap is the time to make the display trigger.

Max straights were 65/69/53/87/93 at different lap times.

Max curves were 47/43/61/18 at different times

One 0 speed (at a stop light)

This is for a "new track" I recorded.


3) I searched some more with fewer +words and found some posts on calibration.

It would be useful to "suggest" a street procedure that would work. For example accel to 20/40/60 (what is suggested?) and brake hard enough just short of abs help(or maybe not that hard?). I have a safe place to do this & good judgement. Does this need to be done EVERY time the phone is moved?

Do both accel & brake have to be "hard" or can I cruise up to say 60, then "panic" brake?

:)
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2004 Corvette Z06
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Re: G meter not moving at all

Post by Harry »

When driving on a track (not downtown during rush hour), you typically either accelerate or brake. This results in a constant up (straight) and down (corner) of speeds. LapTimer calculates the "local min and max positions and speeds" and displays these min / max values some way ahead and behind the respective positions. This allows you to understand the max speed you can go through corners (without watching the changing speedo all the time) and verify the line driven generates high speeds on the following straights.

- Harry
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Re: G meter not moving at all

Post by gplracerx »

Does this need to be done EVERY time the phone is moved?
Yes. Annoying isn't it. You can go to the acceleration display, tap the center and have the option to force a calibration even when standing still. But the yaw calibration will almost certainly be off. Roll and pitch will be off too if the vehicle isn't level when you do this. You can fix yaw after the fact in the g-g plot by rotating the data with respect to the lateral and longitudinal acceleration axes. But that's slow and painful too because, as far as I know, you have to do that for every lap individually.

Throttle calibration is also lost when you switch the engine off.
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Re: G meter not moving at all

Post by gplracerx »

Now if there were a macro to convert an Excel spreadsheet to .hlptrl format, you could fix the calibration after the fact by loading the .csv file into Excel, comparing the accelerometer data to the GPS data and rotating the accelerometer axes to match the GPS data. My programming skills are nowhere near sufficient. C++ or even R would probably be easier if I knew enough.
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Re: G meter not moving at all

Post by froggy47 »

gplracerx wrote:
Does this need to be done EVERY time the phone is moved?
Yes. Annoying isn't it. You can go to the acceleration display, tap the center and have the option to force a calibration even when standing still. But the yaw calibration will almost certainly be off. Roll and pitch will be off too if the vehicle isn't level when you do this. You can fix yaw after the fact in the g-g plot by rotating the data with respect to the lateral and longitudinal acceleration axes. But that's slow and painful too because, as far as I know, you have to do that for every lap individually.

Throttle calibration is also lost when you switch the engine off.
What is your procedure to calibrate? Do you accel hard (full throttle?) How many gears, how fast, brake medium hard, very hard, engage abs hard?

Do we have to go WOT to get the throttle to calibrate? For how long? More than one gear?

For autox events we have to get all this "housekeeping" done in advance, not like doing 5 sessions of a dozen laps each.

THANKS!
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Re: G meter not moving at all

Post by Harry »

froggy47 wrote:
Harry wrote:1) Is this in an overlaid video? In case everything else is fine, I assume acceleration has been reset while driving or calibration has not been done while in the pits. Usually this works automatically, but missing acceleration can happen in one of the above situations. To fix after the fact, select the lap from Lap List and press the Recalculate button. Select Acceleration and adjust the calculated (not measured) lateral acceleration as required. Once back in Lap Details, Revert to the raw video and run the overlay again.
2) These are max and min speeds achieved while driving. Either GPS or OBD based.

- Harry
1) I used +calibrate, +accelerate +brake to search the forum, nothing.

For number 2) it seemed more like max speed straight and max speed on curves, one or 2 min speeds posted

but

they appear 10 times on one lap at different speeds so there is more to this than just one max and one min speed. Some other parameter/sensor is triggering when to display (straight & curve) so I am just trying to understand what makes HLT "decide" this moment of the lap is the time to make the display trigger.

Max straights were 65/69/53/87/93 at different lap times.

Max curves were 47/43/61/18 at different times

One 0 speed (at a stop light)

This is for a "new track" I recorded.


3) I searched some more with fewer +words and found some posts on calibration.

It would be useful to "suggest" a street procedure that would work. For example accel to 20/40/60 (what is suggested?) and brake hard enough just short of abs help(or maybe not that hard?). I have a safe place to do this & good judgement. Does this need to be done EVERY time the phone is moved?

Do both accel & brake have to be "hard" or can I cruise up to say 60, then "panic" brake?

:)
Neither min/max identification nor calibration works off track - all these processes are optimized to work on track. Reducing the requirements / thresholds so it works on public roads would mean it works less reliable on track - which is not an option.

Speed developments on public roads are completely different compared to tracks. You will see a constant speed change up and down and far too many minima / maxima are identified. Min / max speed inserts are shown 4 seconds ahead of reaching the respective min/max position and will remain another 4 seconds until it is completely dimmed again. So the overall visibility is 8 seconds provided no other min/max speed is coming in already (which is not the case on tracks). Autocross tracks raise similar requirements like public streets - I'm aware of this.

To pass the last calibration step you need a hard brake like you do it at the end of a straight on track. On public road, it corresponds to what you name a panic brake ;-) while it is normal on track.

I do not want to change the calibration procedure currently as it will become kind of obsolete in a future version of LapTimer. For street use, I have another app on my roadmap - with completely different requirements.

- Harry
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Re: G meter not moving at all

Post by gplracerx »

froggy47,

As Harry points out, braking works a lot better than acceleration, unless you have an all wheel drive car with lots of horsepower and really good tires. Besides, you might actually be able to brake hard on the way to the starting line from the grid, but they really frown on hard acceleration. Calibration wouldn't be a problem except for two things, you have to rotate the phone 90 degrees to do video, which requires re-calibration. You may have to restart the app if you lose contact with your Bluetooth devices, recalibration again.

I actually had the app calibrate or change calibration in the middle of a run. I wasn't going in a straight line at the time either.

What would be nice for those of us who use ball mounts would be a way to specify the device orientation for calibration rather than have the app determine the orientation after the fact. I'm pretty sure that I can eyeball the orientation of the longitudinal axis as well as the calibration routine.
froggy47
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Re: G meter not moving at all

Post by froggy47 »

Harry wrote:
froggy47 wrote:
Harry wrote:1) Is this in an overlaid video? In case everything else is fine, I assume acceleration has been reset while driving or calibration has not been done while in the pits. Usually this works automatically, but missing acceleration can happen in one of the above situations. To fix after the fact, select the lap from Lap List and press the Recalculate button. Select Acceleration and adjust the calculated (not measured) lateral acceleration as required. Once back in Lap Details, Revert to the raw video and run the overlay again.
2) These are max and min speeds achieved while driving. Either GPS or OBD based.

- Harry
1) I used +calibrate, +accelerate +brake to search the forum, nothing.

For number 2) it seemed more like max speed straight and max speed on curves, one or 2 min speeds posted

but

they appear 10 times on one lap at different speeds so there is more to this than just one max and one min speed. Some other parameter/sensor is triggering when to display (straight & curve) so I am just trying to understand what makes HLT "decide" this moment of the lap is the time to make the display trigger.

Max straights were 65/69/53/87/93 at different lap times.

Max curves were 47/43/61/18 at different times

One 0 speed (at a stop light)

This is for a "new track" I recorded.


3) I searched some more with fewer +words and found some posts on calibration.

It would be useful to "suggest" a street procedure that would work. For example accel to 20/40/60 (what is suggested?) and brake hard enough just short of abs help(or maybe not that hard?). I have a safe place to do this & good judgement. Does this need to be done EVERY time the phone is moved?

Do both accel & brake have to be "hard" or can I cruise up to say 60, then "panic" brake?

:)
Neither min/max identification nor calibration works off track - all these processes are optimized to work on track. Reducing the requirements / thresholds so it works on public roads would mean it works less reliable on track - which is not an option.

Speed developments on public roads are completely different compared to tracks. You will see a constant speed change up and down and far too many minima / maxima are identified. Min / max speed inserts are shown 4 seconds ahead of reaching the respective min/max position and will remain another 4 seconds until it is completely dimmed again. So the overall visibility is 8 seconds provided no other min/max speed is coming in already (which is not the case on tracks). Autocross tracks raise similar requirements like public streets - I'm aware of this.

To pass the last calibration step you need a hard brake like you do it at the end of a straight on track. On public road, it corresponds to what you name a panic brake ;-) while it is normal on track.

I do not want to change the calibration procedure currently as it will become kind of obsolete in a future version of LapTimer. For street use, I have another app on my roadmap - with completely different requirements.

- Harry

Thanks, not asking for changes, I am just trying to understand the what/why/how of the data. Now it is more clear.

Thanks.
Autox & HPDE
2004 Corvette Z06
Moto X/android, Dual 160, generic OBD2
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