DC servo with PID control

Hello, i got some question about DC servo with PID control,for detail i dont know how arduino receive the feedback. With PIC 16f877A, i used ext interrups to count the fulse form motor encoder.
9266b6d6b9f9d30af5d48a5a273b73db03a02421.jpg
This code i gave it form ard library,Input is encoder receive pin and output is PWM pin? Do you think that.
And what aggKp,ConsKp means?? Thanks.

#include <PID_v1.h>
double Setpoint, Input, Output;

double aggKp=4, aggKi=0.2, aggKd=1;
double consKp=1, consKi=0.05, consKd=0.25;

PID myPID(&Input, &Output, &Setpoint, consKp, consKi, consKd, DIRECT);

void setup()
{

Input = analogRead(0);
Setpoint = 100;

myPID.SetMode(AUTOMATIC);
}

void loop()
{
Input = analogRead(0);

double gap = abs(Setpoint-Input);
if(gap<10)
{
myPID.SetTunings(consKp, consKi, consKd);
}
else
{

myPID.SetTunings(aggKp, aggKi, aggKd);
}

myPID.Compute();
analogWrite(3,Output);
}

Input = analogRead(0); The feedback is applied to A0.

And what aggKp,ConsKp means??

The program changes the coefficients (Kp, Ki and Kd depending on the magnitude of the error.

double aggKp=4, aggKi=0.2, aggKd=1;
double consKp=1, consKi=0.05, consKd=0.25;

using the less aggressive tuning when the error is below 10.