Resistance calculation

[brettjurgens]

I've been working on an app for my peloton on and off for the last few years. Your blog posts were incredibly helpful in helping get the sensor data.

I thought I could help out a little bit... From what I've found, the proper way to calculate resistance is:

// CALIBRATION is a float array

private fun getCalibrationValue(raw: Float, i: Int): Float {
    if (i == 0) return 0.0f
    val prevIndex = i - 1
    val prevIndexVal = CALIBRATION[prevIndex]
    val currIndexVal = CALIBRATION[i]
    val size = CALIBRATION.size
    var f = 0f
    if (currIndexVal > prevIndexVal) {
        f = (raw - prevIndexVal) / (currIndexVal - prevIndexVal)
    }
    return (prevIndex.toFloat() + f) * 100.0f / (size - 1).toFloat()
}

fun calculateResistance(raw: Float): Float {
    val calibrationLen = CALIBRATION.size
    if (raw < CALIBRATION[0]) return 0.0f
    if (raw > CALIBRATION[calibrationLen - 1]) return 100.0f
    if (raw < CALIBRATION[3]) return (raw - CALIBRATION[0]) * 10.0f / (CALIBRATION[3] - CALIBRATION[0])
    if (raw > CALIBRATION[27]) return (raw - CALIBRATION[27]) * 10.0f / (CALIBRATION[30] - CALIBRATION[27]) + 90.0f
    for (i in 0 until calibrationLen) {
        if (raw >= CALIBRATION[i]) continue
        return getCalibrationValue(raw, i)
    }
    return -1.0f
}

Hope this is helpful!