/**
* Calculate power array
*
* A constant factor of 1.5 was used in previous versions - and I don't know why.
* Without this factor results equal standard tools.
*
* @author Nils Frohberg
* @author Hannes Christiansen
* @see http://www.blog.ultracycle.net/2010/05/cycling-power-calculations
* @param int $weight [kg] Weight of rider and bike
* @param float $powerFactor constant factor
* @return array
*/
public function calculate($weight = 75, $powerFactor = 1.0)
{
if (!$this->Trackdata->has(Trackdata\Entity::TIME) || !$this->Trackdata->has(Trackdata\Entity::DISTANCE)) {
return [];
}
$everyNthPoint = ceil($this->Size / 1000);
$n = $everyNthPoint;
$grade = 0;
$calcGrade = $this->knowsRoute() && $this->Route->hasElevations();
$ArrayTime = $this->Trackdata->time();
$ArrayDist = $this->Trackdata->distance();
$ArrayElev = $this->knowsRoute() ? $this->Route->elevations() : array();
$Frl = $weight * self::GRAVITY * self::CRR;
$Fwpr = 0.5 * self::AREA * self::CW * $this->rho();
$Fslp = $weight * self::GRAVITY;
for ($i = 0; $i < $this->Size - 1; $i++) {
if ($i % $everyNthPoint == 0) {
if ($i + $n > $this->Size - 1) {
$n = $this->Size - $i - 1;
}
$distance = ($ArrayDist[$i + $n] - $ArrayDist[$i]) * 1000;
$grade = $distance == 0 || !$calcGrade ? 0 : ($ArrayElev[$i + $n] - $ArrayElev[$i]) / $distance;
}
$distance = $ArrayDist[$i + 1] - $ArrayDist[$i];
$time = $ArrayTime[$i + 1] - $ArrayTime[$i];
if ($time > 0) {
$Vmps = $distance * 1000 / $time;
$Fw = $Fwpr * $Vmps * $Vmps;
$Fsl = $Fslp * $grade;
$this->Power[] = round(max($powerFactor * ($Frl + $Fw + $Fsl) * $Vmps, 0));
} else {
$this->Power[] = 0;
}
}
$this->Power[] = $this->Power[$this->Size - 2];
/* XXX */
return $this->Power;
}
