1st Feature Speed Test

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

Checking the Results

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)