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post #1 of 19 Old 02-16-2015, 09:05 PM Thread Starter
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A request for assistance in gathering data

I'm hoping this won't come up dry as usually happens but here goes: there are some smart phone accelerometer aps available for free. I'm hoping that several people will download and do some panic braking in order to share the data. I asked on another group also but no dice as yet, excepting that one person observed that he questioned how valid would be the data, given different mounting, etc.

So, there are two things:
1) Can anyone speak to the technical problems in using these aps on various phones to gather comparative data?

2) Will some of you please do some hard braking (hard as possible) from 45 mph to stopped and report the graphs?

It would be most interesting and potentially useful if we had some average numbers with which to compare. When someone is questioning the effectiveness of their brakes, information as to braking performance could point to whether their brakes are typical or less effective.

We plan to do a series of tests when Mike has time to bring his stock Gen1 and hope to have data for comparison as follows:

1) Stock Gen1 with standard pads.
2) Gen1 with 250 Ninja master cylinder
3) Gen1 with 320 EBC rotor and 250 Ninja master
4) Gen1 with 320 EBC rotor and stock master
5) Gen1 with Gen2 front rotor and SV650 caliper
6) Gen1 with Gen2 front rotor, SV650 caliper and 250 Ninja master (same as my bike)

I would like to compare to a stock Gen2 and to try a Gen2 front caliper on the Gen1 but am dissuaded by the need to fabricate the adapter when will definitely not be running the Gen2 caliper. It would also be interesting to try the SV caliper with the 320 EBC rotor but, again, the adapter plate fabrication is too much for simple curiosity since won't be running that combination either.

I do recall that some were running the SV+ 320 so maybe someone will offer data?
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post #2 of 19 Old 02-16-2015, 10:40 PM
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Why not perform stopping distance tests from known speeds?

Just askin'!

Otherwise, how do the smart phone accelerometers work? Integrated/differentiated GPS position readings vs. time? Bolt-on accelerometers?

Just wonderin'!

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post #3 of 19 Old 02-16-2015, 11:09 PM Thread Starter
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Stopping distances from various speeds is the back up plan but the little I did with an accelerometer on my phone showed a graph which offered more information since it accurately displayed the deceleration profile and allowed one to identify the deceleration rate between speeds. That should remove some of the problems with speedo variations (mine & Mikes have been corrected for speed while most have not).

I'm also interested in the use of the technology since is seems to offer more information and simpler as not requiring measuring, etc. When doing simple comparisons, we'd put some objects in the tank bag, then run up to speed and nail the brakes at a predetermined point. When stopped an object would be dropped to the roadside level with the foot peg, then repeat.

I'm not much better informed regarding the phone ap but as recall I had to have GPS on and that they use the phone's built in accelerometers. I tend to expect that the younger types will be more aware of this tech and hope that we can work out whether the use is reliable.

I need to get my ap out and play with it to get up to speed again but not now as Rupert the house rabbit is bugging me for treats so will get no peace. :-)

Have a look and let me know what you think of the aps.
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post #4 of 19 Old 02-17-2015, 03:50 AM
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Quote:
Originally Posted by Normk View Post
I'm not much better informed regarding the phone ap but as recall I had to have GPS on and that they use the phone's built in accelerometers. I tend to expect that the younger types will be more aware of this tech and hope that we can work out whether the use is reliable.

I need to get my ap out and play with it to get up to speed again but not now as Rupert the house rabbit is bugging me for treats so will get no peace. :-)

Have a look and let me know what you think of the aps.
No speaka "aps," Normk!

Did not realize cell phones (all?) are equipped with accelerometers.

Differentiating distance vs. time gives speed (as our GPS receivers do); the second derivative, the rate speed changes, should yield acceleration. Reckon that's a doable do with a GPS receiver, but . . . unsure whether all cell phones have GPS receivers.

Regardless, intriguing possibilities and interesting subject Normk; thanks for raising it.

--------------------------------

Back to measuring stopping distances, looks like using a GPS receiver to set the approach speed might be more accurate/convenient than using even a calibrated speedometer. While measuring distances is a drag, if distinguishable markers could be laid down and left in place for each trial, only one measurement from the starting point of the tests would be required.

The motorcycle magazines still use stopping distances when testing motorcycles, perhaps because this measurment has become a "convention," even though more precise and accurate measurement techniques and instrumentation are available.

=============================

Way leads onto way!

At least, SOME cell phones, apparently, have built-in accelerometers:

http://www.engadget.com/2012/05/22/t...rometer-works/



---------------------------------------
======================

Just speculating; an on-board accelerometer (piece of hardware) may be more useful than GPS location-vs.-time differentiation to determine acceleration, because . . . the "Z," or vertical, component is the most difficult and least accurate of the axes determinable from navigation satellite ephemera; a geometric fact-of-life. Z-axis uncertainties may degrade acceleration data synthesized from GPS positioning information . . . DISCLAIMER: Speculation only, I have no evidentiary basis for the concept.

Last edited by Damocles; 02-17-2015 at 04:29 AM.
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post #5 of 19 Old 02-17-2015, 12:21 PM Thread Starter
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You have very proficiently outlined the picture. The last several models of smart phones which we have had have accelerometers. I understand that they are used for many phone functions. I do have to get back to playing with the one I tried a year or so ago because not certain that it also uses GPS. My dad has dementia and we are looking at various changes to their house to distracted from this somewhat so please excuse the increased level of confusion on my part. :-)

If you have time, try one of the phone aps and see what you take from the experience. I would be appreciative of the perspective.



Quote:
Originally Posted by Damocles View Post
No speaka "aps," Normk!

Did not realize cell phones (all?) are equipped with accelerometers.

Differentiating distance vs. time gives speed (as our GPS receivers do); the second derivative, the rate speed changes, should yield acceleration. Reckon that's a doable do with a GPS receiver, but . . . unsure whether all cell phones have GPS receivers.

Regardless, intriguing possibilities and interesting subject Normk; thanks for raising it.

--------------------------------

Back to measuring stopping distances, looks like using a GPS receiver to set the approach speed might be more accurate/convenient than using even a calibrated speedometer. While measuring distances is a drag, if distinguishable markers could be laid down and left in place for each trial, only one measurement from the starting point of the tests would be required.

The motorcycle magazines still use stopping distances when testing motorcycles, perhaps because this measurment has become a "convention," even though more precise and accurate measurement techniques and instrumentation are available.

=============================

Way leads onto way!

At least, SOME cell phones, apparently, have built-in accelerometers:

http://www.engadget.com/2012/05/22/t...rometer-works/



---------------------------------------
======================

Just speculating; an on-board accelerometer (piece of hardware) may be more useful than GPS location-vs.-time differentiation to determine acceleration, because . . . the "Z," or vertical, component is the most difficult and least accurate of the axes determinable from navigation satellite ephemera; a geometric fact-of-life. Z-axis uncertainties may degrade acceleration data synthesized from GPS positioning information . . . DISCLAIMER: Speculation only, I have no evidentiary basis for the concept.
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post #6 of 19 Old 02-17-2015, 12:56 PM
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My farting about with GPS has shown that the lag time that the unit has with respect to changes n speed would make it less than optimal for trying to measure rapid changes in acceleration or speed.

I take great pride in my insistence in sticking with a dumb phone, but I do have a 7" Galaxy tablet that has accelerometers in it. I'll see if there is an app for it that might be useful and fiddle a bit.

My front brake is not working optimally at the moment and I need to do a rebuild. If feels a bit crunchy and I suspect things are a bit grungy down in the caliper. I could combine the rebuild with some data gathering.

"It'll help keep me off of the bar stool," Tom said experimentally...

Tom

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Last edited by Tom Schmitz; 02-17-2015 at 01:43 PM.
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post #7 of 19 Old 02-17-2015, 01:43 PM
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This seems to be a good app for Android devices.

I'm going to have a go at it.

Tom

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“She went out slowly. The way she did it hadn’t been learned at business college.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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post #8 of 19 Old 02-17-2015, 02:52 PM Thread Starter
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Please, please do a before and after for your brakes. That will serve both you and us in separate ways: we will benefit from the contrast and you will benefit from being able to delay getting off the stool a bit longer.



Quote:
Originally Posted by Tom Schmitz View Post
My farting about with GPS has shown that the lag time that the unit has with respect to changes n speed would make it less than optimal for trying to measure rapid changes in acceleration or speed.

I take great pride in my insistence in sticking with a dumb phone, but I do have a 7" Galaxy tablet that has accelerometers in it. I'll see if there is an app for it that might be useful and fiddle a bit.

My front brake is not working optimally at the moment and I need to do a rebuild. If feels a bit crunchy and I suspect things are a bit grungy down in the caliper. I could combine the rebuild with some data gathering.

"It'll help keep me off of the bar stool," Tom said experimentally...

Tom
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post #9 of 19 Old 02-17-2015, 03:11 PM
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Quote:
Physics Toolbox Accelerometer



This accelerometer app measures and displays a graph of G-Force vs. Time(s) that can be exported in an e-mail as a .txt attachment with comma separated values (csv). G-Force and acceleration measured in the x, y, and z dimensions are displayed separately on the graph, and the total vector sum is displayed digitally.
Who could ask for anything more?

Just a guess, but . . . I imagine precise orientation of the accelerometer platform (the cellphone, tablet, whatever) with respect to the bike's axes, especially the axis of forward motion, will simplify data collection and analysis.

Disclaimer: I have a dumb phone.

Great marketing idea: Offer for sale a GPS receiver with accelerometer and app built-in.

WAIT! It's been done already! (At least, it WAS done, at one time.):

https://www.sparkfun.com/products/retired/9838

Last edited by Damocles; 02-17-2015 at 03:15 PM.
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post #10 of 19 Old 02-17-2015, 03:32 PM
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Damocles -

I'm still learning about this but orientation is critical, it would seem.

There are two programs I have tired so far. The first would display X, Y, Z, pitch, roll, and yaw. It seemed overly complicated and, as far as I could tell, couldn't record data and save it to a file.

The one I chose will show X, Y, and Z and total G force, where X is to the right and left, Y is up and down, and Z is forward and backward IF you are holding the table facing you and oriented vertically. The definitions change with respect to the earth if you change the tablet's orientation, of course.

The app can display none or all of the axes and can record at command. Once the recording is stopped it will prompt for a file name, which it saves in CSV format. Irrespective of what is displayed it records all data.

The bugaboo is that I have to figure out some way to mount it to rigidly mount it to the bike in a vertical position. That would be best, but I suppose most any other way could be made to work. I'll have to look and see what RAM offers by way of a mount.

Tom

Tom [email protected]

“She went out slowly. The way she did it hadn’t been learned at business college.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.
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