Measuring Stride

In order to compute the distance travelled, we need to calibrate the relationship between speed and stride. In this experiment, the runner needs to do multiple runs of the same a distance at various steady speeds. On each run, the micro:bit will measure the running time and the number of foot strikes.

Find a running track!

Find a location where you can run at least 20m at a constant pace. A good example would be a run between the free-throw areas on a basketball court. It is important that the runner is able to enter, run through, and leave the track at a constant speed. If you are able to find a longer distance and run steadily over that distance, the results will be better. In the original Puma calibration, the runner had to run a full track!

Measure the distance between the start and the end of the track and store this value as TD.

Code the micro:bit s

The experiment will be operated with 2 micro:bit that communicate via radio.

• The first micro:bit, slipped inside in the runner’s sock, measures the foot strikes. It runs continuously and the runner does not have to do anything, aside from focusing on their running.
• The second micro:bit is operated on the sideline and, just like a stopwatch, measures the start and stop times of the run.

Runner micro:bit

input.onGesture(Gesture.ThreeG, function () {
    game.addScore(1)
    radio.sendNumber(game.score())
})
radio.setGroup(1)
radio.setTransmitPower(7)
basic.showString("RUNNER")

Operator micro:bit

The operator needs to press button A when the runner enters the track and B when the runner leaves the track. Then the micro:bit displays the measurement in a loop.

input.onButtonPressed(Button.B, function () {
    recording = false
    time = (input.runningTime() - start) / 1000
    while(true) {
        basic.showString("TIME")
        basic.showNumber(time)
        basic.showString("STEPS")
        basic.showNumber(game.score())
    }
})
radio.onReceivedNumber(function (receivedNumber) {
    if (recording) {
        game.addScore(1)
    }
})
input.onButtonPressed(Button.A, function () {
    start = input.runningTime()
    game.setScore(0)
    recording = true
    basic.showIcon(IconNames.Butterfly)
})
let start = 0
let time = 0
let recording = false
basic.showString("OPERATOR")
radio.setGroup(1)

Recording!

Bring both micro:bit connected to their battery packs. Slip the runner’s micro:bit into the sock of the runner and have the runner get ready to do a few runs. The operator should be positioned so that they have a clear view of the start and end of the track. The operator should also have a notebook or computer to write down the data of each run.

• When the runner crosses the start of the track, the operator presses on button A.
• When the runner leaves the track they press B.
• After pressing B, the micro:bit will display the time and number of steps twice. Take note of those values and record them in a table.

radio