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Page last modified 23:53, 18 Jul 2009 by internetscooter
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User:Internetscooter > Scooter Computer > 1st Feature Speed Test

1st Feature Speed Test

From $1

    First feature is a speed calculation based on wheel speed. Internally it is measured in metres per second and is triggered by a reed switch, which triggers an interrupt. Th first test is to see how fast we can measure and check a few things out like if debouncing is needed (i.e. handling reed switch noise).

    The Test

    To do the test I placed a magnet on the lathe spindle and a pickup on the slide. I then could adjust speed and distance between pick-up and magnet.

    The Results

    The results are as follows:

    103 rpm = reads 8.4 km/hr
    630 rpm = reads 50.9 km/hr
    1209 rpm = reads 97.8 km/hr
    2432 rpm = reads 197.3 km/hr (using last rpm with 2 magnets)
    It had no problems with a gap up to 10mm (did not test for bigger gap)

    Checking the Results

    PICT1379.JPG

    Wheel circumference = 1.345 metres

    1209 rpm = 1.345 metres x 1209 rpm = 1626.1 metres per minute

    1626.1 metres per minute = 97566 metres per hour = 97.6 km per hour

    Actual reading was 97.8 km/hr

    With two magnets 1216 rpm = 196.3 km/hr. Actual reading was 197.3 km/hr

    Conclusions

    Success!

    • The Scooter Computer can easily calculate high speeds up to 200 km/hr (possibly more but I ran out of rpm on the lathe)  
    • The expected real gap between sensor and magnet when fitted on scooter should not be a problem with sensitivity
    • There is a slight difference between lathe rpm and speed reading (unknown who is wrong*)
    • Internally there are no problems with processor speed calculating speed every revolution
    • No problems with sensor bounce

    * lathe is like to be wrong as the rpm reading varies while it is running by 2% (i.e. rpm is not 100% constant)

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