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  #11  
Old 10-01-18, 14:54
kano nordie kano nordie is offline
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I just wish I could understand even a little of what you are doing?
John
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  #12  
Old 10-01-18, 15:31
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grahamb grahamb is offline
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I'm trying to keep it simple John.

ADC is an Analogue to Digital Convertor, it basically converts the voltage from the attached sensors, in to numbers that the program can then work with.

So for a 16bit ADC, it can provide values from 0 to 65535, for voltages from 0 to 5V, in 65535 steps (.07629mV resolution). The ADC board I've chosen has four inputs on it, so the Pi can read each input independently of the other.

This will be more than sensitive enough to measure the movement from the suspension.

I'm working on some macros in Excel, to analyse the data captured by the Pi. They provide 0-10-20-30-40-50-60 times, max speeds, max altitudes so far. Pretty basic, as its more about verifying the data captured at the moment.

Last edited by grahamb; 10-01-18 at 16:12.
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  #13  
Old 10-01-18, 17:27
webby webby is offline
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I am glad you are keeping it simple.......!
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  #14  
Old 11-01-18, 06:39
kano nordie kano nordie is offline
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Quote:
Originally Posted by webby View Post
I am glad you are keeping it simple.......!
Still beyond the comprehension of "village" folk like me
In your "spare time" perhaps I can persuade you to to check over my paddle shift and very basic info download
John
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  #15  
Old 12-01-18, 10:51
bladeyboy bladeyboy is offline
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Nice project, Graham. I am planning something similar for next season.
But you are way ahead of me. Currently I just have a pile of Pi zeros, GPS modules, accelerometer modules, gyroscope modules, temperature modules, ultrasonic modules, and whatever other sensors I could think of.

Are you powering it from a battery?
Are you starting and stopping logging automatically?
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  #16  
Old 12-01-18, 13:11
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Quote:
Originally Posted by bladeyboy View Post
Nice project, Graham. I am planning something similar for next season.
But you are way ahead of me. Currently I just have a pile of Pi zeros, GPS modules, accelerometer modules, gyroscope modules, temperature modules, ultrasonic modules, and whatever other sensors I could think of.

Are you powering it from a battery?
Are you starting and stopping logging automatically?
Its so easy to acquire parts isn't it I've just put mine in to a https://www.modmypi.com/blog/introdu...raspberry-pi-b transparent Modmypi modular case so its a bit safer to lug around and test.

I've been running it from a 6000mAh battery I bought from Tesco for £12. It claims to give 2.5A output, but I've been seeing lightning symbols on the screen as the HAT is energised, which indicates under voltage on the Pi3, so today I'm running it off a USB cigar lighter charger in the car, which claims is also rated at 2.5A.

I've been writing a new control loop algorithm this week, to allow it to close/open files automatically as the speed drops to zero and climbs above zero, and I'll test that out next week. This week has been about collecting data, and checking it for accuracy etc.

I've yet to find a HAT that does all the jobs, ie gps, gyro, gprs, adc, but I'm still looking. As it is, this will need two HATs stacked, hence the modular case.
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  #17  
Old 12-01-18, 18:44
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Excel Macros are now working. This is the data captured in the tow car today.
The macro searches for speed=0, then finds when speed starts to rise, and at the point where the acceleration ends, it gives a summary of the 0-60 times in 10mph increments.


Worksheet: capture_2018-01-12-12-51-13
Log file contains 7286 samples
Captured in 727.9 seconds

Max speed reached before deceleration 77.1
[Data rows 3597 to 3706 ]
0 - 10 - 20 - 30 - 40 - 50 - 60 (0-60)
0 0.6 0.6 0.8 0.8 1.3 1.3 5.4


Max speed reached before deceleration 76.1
[Data rows 4417 to 4579 ]
0 - 10 - 20 - 30 - 40 - 50 - 60 (0-60)
0 0.6 0.5 0.8 0.8 1.3 1.2 5.2
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  #18  
Old 14-01-18, 21:01
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The ADC HAT card is now working and samples at 10hz. I'll hook the suspension pots to it this week and see how the data looks.
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  #19  
Old 14-01-18, 23:29
jouhar jouhar is offline
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I am not sure you will get any meaningful suspension data at only 10 samples per second - if I were doing this project I would want to sample suspension movement at a minimum of 50 Hz or if that wasn't possible, I would write some code to interpolate between readings and get a much smoother data set. I could be wrong though.....

Having said all that, you are doing a great job with low cost items and it's an interesting thread to read. Best of luck with it !
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  #20  
Old 15-01-18, 08:40
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At 12bit resolution, the board will support 240hz, so as I've 4 channels to record I could sample at 60hz

#12 = 12 bit (240SPS max)
#14 = 14 bit (60SPS max)
#16 = 16 bit (15SPS max)
#18 = 18 bit (3.75SPS max)

However, I don't know yet if the pi, interpreting python, will run at that speed, so I may have to look at compiling the code or changing to something like C#

Last edited by grahamb; 15-01-18 at 09:21.
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