PID.py

class pid:
    _kp = _ki = _kd = _output_max = _imax = 0

    def __init__(self, p=0, i=0, d=0, i_max=0, output_max=0):
        self._kp = float(p)
        self._ki = float(i)
        self._kd = float(d)
        self._i_max = abs(i_max)
        self._output_max=abs(output_max)

    def calculate_pid(self, error):
        I_out=0

        P_out= error * self._kp
        I_out+=error * self._ki
        D_out=error*self._kd
        if I_out>self._i_max:
            I_out=self._i_max
        elif I_out<-self._i_max:
            Iout=-self._i_max
        output=P_out+I_out+D_out
        if output>self._output_max:
            output=self._output_max
        elif output<-self._output_max:
            output=-self._output_max
        return output