encoder with pid controller

Projects Programming
1

I encounter the following problems:
1)I need just a bit more precision. So i want to count 1/2 ticks. I got the code from here post 21. I edit it, but it doesn't work for LeftEncoderASet.
2)How can i set a value of ticks and goes exactly in that value.
3)How can i find the dead zone of the dc motor and embed it in the code.

#include <digitalWriteFast.h>
 // Quadrature encoders
// Left encoder
#define c_LeftEncoderInterrupt 0
#define c_LeftEncoderPinA 2
#define c_LeftEncoderInterrupt 1
#define c_LeftEncoderPinB 3
#define LeftEncoderIsReversed
//
volatile bool _LeftEncoderASet;
volatile bool _LeftEncoderBSet;

volatile long _LeftEncoderTicks = 0;


//Variables for PID
double Setpoint=1350.0;//h timi p thelw na paei
unsigned long lastTime;
double errSum, lastErr;
double Input, Output;
double kp=0.009;
double ki=0;
double kd=0;
int SpeedPin=5;
int motorPin1=6;
int motorPin2=7;

//Send command to DC motor
void loop(){
 


Input=_LeftEncoderTicks;
Compute();
if(Output > 0) {
CC();
}
else if(Output<=0){
CCW();
}

Serial.print(_LeftEncoderTicks);
Serial.print("\n");

delay(20);
}

//Motor Control Function
void CC(){
digitalWrite(motorPin1,LOW);
digitalWrite(motorPin2,HIGH);
analogWrite(SpeedPin, abs(Output));//abs apoliti t
}
void CCW(){
digitalWrite(motorPin1,HIGH);
digitalWrite(motorPin2,LOW);
analogWrite(SpeedPin, abs(Output));
}


//Compute controller output by PID algorithm

void Compute()
{
   /*How long since we last calculated*/
   unsigned long now = millis();
   double timeChange = (double)(now - lastTime);
  Input=_LeftEncoderTicks;
   /*Compute all the working error variables*/
   double error = Setpoint - Input;
   errSum += (error * timeChange);
   double dErr = (error - lastErr) / timeChange;
  
   /*Compute PID Output*/
   Output = ((kp * error + ki * errSum + kd * dErr)+60);
  
   
 if(Output>255){Output = 255;}
else if(Output <-255){Output = -255;}
else{}
  
   /*Remember some variables for next time*/
   lastErr = error;
   lastTime = now;
}

void setup()
{
Serial.begin(115200);

// Quadrature encoders
// Left encoder
pinMode(c_LeftEncoderPinA, INPUT); // sets pin A as input
digitalWrite(c_LeftEncoderPinA, LOW); // turn on pullup resistors
pinMode(c_LeftEncoderPinB, INPUT); // sets pin B as input
digitalWrite(c_LeftEncoderPinB, LOW); // turn on pullup resistors
_LeftEncoderASet = digitalReadFast(c_LeftEncoderPinA);   // read the input pin
_LeftEncoderBSet = digitalReadFast(c_LeftEncoderPinB);   // read the input pin
attachInterrupt(c_LeftEncoderInterrupt, HandleLeftMotorInterruptA, RISING);
attachInterrupt(c_LeftEncoderInterrupt, HandleLeftMotorInterruptB, RISING);
pinMode(motorPin1, OUTPUT);
pinMode(motorPin2, OUTPUT);
pinMode(SpeedPin, OUTPUT);

// Left encoder
pinMode(c_LeftEncoderPinA, INPUT); // sets pin A as input
digitalWrite(c_LeftEncoderPinA, HIGH); // turn on pullup resistors
pinMode(c_LeftEncoderPinB, INPUT); // sets pin B as input
digitalWrite(c_LeftEncoderPinB, HIGH); // turn on pullup resistors
_LeftEncoderASet = digitalReadFast(c_LeftEncoderPinA);   // read the input pin
_LeftEncoderBSet = digitalReadFast(c_LeftEncoderPinB);   // read the input pin
attachInterrupt(c_LeftEncoderInterrupt, HandleLeftMotorInterruptA, FALLING);
attachInterrupt(c_LeftEncoderInterrupt, HandleLeftMotorInterruptB, FALLING);
pinMode(motorPin1, OUTPUT);
pinMode(motorPin2, OUTPUT);
pinMode(SpeedPin, OUTPUT);
}


// Interrupt service routines for the left motor’s quadrature encoder
void HandleLeftMotorInterruptA()
{
// Test transition
  _LeftEncoderASet = digitalReadFast(c_LeftEncoderPinA);   // read the input pin
  _LeftEncoderBSet = digitalReadFast(c_LeftEncoderPinB);   // read the input pin

  // and adjust counter + if A leads B
 #ifdef LeftEncoderIsReversed
 _LeftEncoderTicks += (_LeftEncoderASet != _LeftEncoderBSet) ? -1 : +1;
 #else 
 _LeftEncoderTicks -= (_LeftEncoderASet != _LeftEncoderBSet) ? -1 : +1;
#endif
}
// Interrupt service routines for the left motor’s quadrature encoder
void HandleLeftMotorInterruptB()
{
// Test transition
  _LeftEncoderASet = digitalReadFast(c_LeftEncoderPinA);   // read the input pin
  _LeftEncoderBSet = digitalReadFast(c_LeftEncoderPinB);   // read the input pin

  // and adjust counter + if A leads B
 #ifdef LeftEncoderIsReversed
 _LeftEncoderTicks += (_LeftEncoderASet != _LeftEncoderBSet) ? -1 : +1;
 #else
 _LeftEncoderTicks -= (_LeftEncoderASet != _LeftEncoderBSet) ? -1 : +1;
 #endif
}
2

kostas15:
2)How can i set a value of ticks and goes exactly in that value.
3)How can i find the dead zone of the dc motor and embed it in the code.

Sorry, I don't understand the question.

Perhaps it would help to consider your encoder value as a number of half-ticks, semi-ticks etc. So you are still dealing with an integer value.

If you want to drive the motor until the encoder position reaches a specified value then the method of doing it with semi-ticks is exactly the same as with ticks - it is just an integer value which will be less than, more than or exactly equal to the target position.

What do you mean by the dead zone?

3

By the term dead zone i mean the values of pwm that doesnt move the dc motor. I have to find this. for example till 65 it doesnt move, so i ll add +65 to eliminate the dead zone.
What do you mean semi- ticks? 1/4?
It's an encoder from a printer and i have to count raising and falling. My goal is to set an exactly value to set_point and the motor drives to that.