FORUM.M.NU

Kod: Markera allt

<?php

// Debug?
define("DEBUG", true);

// Declare variables
$DeltaTime = 10;
$Continue = true;
$OutdoorTemp = 2;

// Quit nicely when asked to
function SignalHandler($signal)
{
	switch ($signal) {
		case SIGTERM:
		case SIGINT:
			$Continue = false;
			break;
	}
}

// Linear interpolation between two known points
function Interpolate($x0, $y0, $x1, $y1, $x)
{
	if ($x == $x0)
		return $y0;
	if ($x == $x1)
		return $y1;
	else
		return $y0+($x-$x0)*($y1-$y0)/($x1-$x0);
}

// Sets the valve position between 0 and 100 %
function SetValvePosition($position)
{
	$Temp = Interpolate(0, 255, 100, 0, $position);
	$Output = round(min(max(intval($Temp), 0), 255));
	exec("owwrite -s 192.168.1.2 /shunt/wiper $Output");
	echo "Wrote $Output to wiper\n";
}

function PIDController($setpoint, $actual_value)
{
	$PGain = 1.0;
	$IGain = 0.1;
	$DGain = 10.0;
	global $DeltaTime;
	static $PreviousError = 0;
	static $IntegralPart = 0;

	// Calculate deviation
	$Error = $setpoint - $actual_value;

	// Proportional part
	$Proportional = $PGain * $Error;

	// Integral part
	$IntegralPart = $IntegralPart + $Error * $DeltaTime;
	$Integral = min(max($IGain * $IntegralPart, -100), 100);

	// Derivative part
	$Derivative = $DGain * ($Error - $PreviousError)/$DeltaTime;

	// Combine P, I and D
	$Output = $Proportional + $Integral + $Derivative;

	// Limit output
	$Output = min(max($Output, 0), 100);

	if (DEBUG) echo "Regulator output: ".round($Output, 1)." %\n";
	if (DEBUG) echo "P: ".round($Proportional, 1);
	if (DEBUG) echo " I: ".round($Integral, 1);
	if (DEBUG) echo " D: ".round($Derivative, 1)."\n";

	// Update error
	$PreviousError = $Error;

	return $Output;
}


// Setup signal handler
pcntl_signal(SIGTERM, "SignalHandler");

// Main loop
while ($Continue)
{
	// Get supply temp
	$SupplyTemp = floatval(exec("owread -s 192.168.1.2 /uncached/framledning_rad/temperature"));
	if (DEBUG) echo "Supply temperature: $SupplyTemp C\n";

	// Get outdoor temp
	// implement later

	// Calculate setpoint
	$Setpoint = Interpolate(-20, 50, 20, 20, $OutdoorTemp);
	if (DEBUG) echo "Setpoint: $Setpoint C\n";

	// Call PID regulator
	$PIDOutput = PIDController($Setpoint, $SupplyTemp);

	// Set the valve position
	SetValvePosition($PIDOutput);
	
	// Wait a while
	sleep($DeltaTime);
}
?>