class PID { private $lastMicrotime = 0; private $deltaTime = 0; private $integral = 0; private $errorPrevious = 0; private $setPoint = 0; private $errorCurrent = 0; private $Kp = 0; private $Ti = 0; private $Td = 0; private $min = 0; private $max = 0; public function __construct(float $setPoint, float $Kp, float $Ti, float $Td, float $min, float $max) { if($this->min >= $this->max) { return false; } $this->lastMicrotime = microtime(true); $this->setPoint = $setPoint; $this->Kp = $Kp; $this->Ti = $Ti; $this->Td = $Td; $this->min = $min; $this->max = $max; } /** * This is considered the "Parallel" form of the PID Algorithm */ public function run(float $actual, $deltaTime=false) { $this->errorCurrent = ($this->setPoint - $actual); if($deltaTime !== false) { $this->deltaTime = $deltaTime; } else { $this->deltaTime = microtime(true) - $this->lastMicrotime; $this->lastMicrotime = microtime(true); } $proportional = $this->CalculateProportional(); $integral = $this->CalculateIntegral(); $derivative = $this->CalculateDerivative(); return ($proportional+$integral+$derivative); } private function CalculateProportional() { return ($this->Kp * $this->errorCurrent); } private function CalculateIntegral() { if($this->Ti == 0) { return 0; } if(($this->integral >= $this->min) && ($this->integral max)) { $this->integral = (($this->deltaTime * $this->errorCurrent) / $this->Ti) + $this->integral; } return $this->integral; } private function CalculateDerivative() { if($this->Td == 0) { return 0; } $delta = (($this->Td / $this->deltaTime) * ($this->errorPrevious - $this->errorCurrent)); $this->errorPrevious = $this->errorCurrent; return $delta; } public function setMinMax(float $min, float $max) { $this->min = $min; $this->max = $max; }}