I am working to control the speed in my line following Robot (using arduino uno),by using proportional constant Kp in a closed loop, in my code I calculate the RPM from The Right Motor and the Left Motor,I used Timer2 interrupt every 50ms to calculate the speed (Rpm) from these Encoders.
I used Timer 0 and Timer 1 to generate pwm signals with a VARIETY duty-cycle=75 % to control the tow motors speed, I measured The RPM for the Left Motor by using Tachometer it is 100 RPM, I changed the Kp constant But my Encoder Output still Give me about 80 RPM (no change).
so my question is : is there any problem in my code or the way I do the controlling loop or understanding the controlling loop.
This is the Code :
//encoders variable
volatile bool counting;
volatile unsigned long events0;//the number of pulses from Left Motor in 50 ms;
volatile unsigned long events1;//the number of pulses from Right Motor in 50 ms;
double n1=540;//the number of pulses in one turn for the Right Encoder;
double n2=540;//the number of pulses in one turn for the Left Encoder;
//end of encoders variable
//PID controller Variable.
double setpoint=100; // Reference speed;
const int Kp=10;
const int Ki=0;
const int Kd=0;
double measuredRightRpm_value;//speed in RPM from Right encoder/Motor;
double measuredLeftRpm_value;//speed in RPM from Left encoder/Motor;
volatile signed long erorR;//Eror from Right Encoder;
volatile signed long erorL;//Eror from Left Encoder;
volatile signed long Eror;
//End of PID controller Variable.
//Timer 2 over flow interrupt
int x = 0, flag = 0;
ISR (TIMER2_OVF_vect)
{
TCNT2=0x64;//for 10 ms
x++;
if(x==5) //to get 50 ms
{
flag = 1;
x=0;
}
} // end of ISR
void eventISR ()
{
if (counting)
events0++;
} // end of eventISR
void eventISR1 ()
{
if (counting)
events1++;
} // end of eventISR1
void setup ()
{
//setup Timer 0 and Timer 1 to generate Pwm signals
TCCR0A=0xB3;
TCCR0B=0x02; // set Timer 0 to clk/8 HZ ,fast PWM mode,tow signal inverted to each other.
TCCR1A=0xB1;// set Timer 1 to clk/8 HZ ,fast PWM mode,tow signal inverted to each other.
TCCR1B=0x0A;;
TCCR2A=0x00;//timer 2 overflow interrupt to calculate RPM from Encoder
TCCR2B=0x07;
TCNT2=0x64;
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(9,OUTPUT);
pinMode(10,OUTPUT);
//end of Timers setup for generating PWM and interrupts.
//Encoder Setup
Serial.begin (9600);
Serial.println ();
pinMode (2, INPUT_PULLUP);
attachInterrupt (0, eventISR, RISING);
attachInterrupt (1, eventISR1, RISING);
// end of Encoder setup
counting = true;
// Timer/Counter 2 Interrupt(s) initialization
TIMSK2=0x01;
interrupts ();
} // end of setup
void showResults ()
{
Serial.print ("the speed (RPM) for the Left Motor = ");
Serial.println ((events0/n1)*(60000/50));
measuredLeftRpm_value=(events0/n1)*(60000/50);
//Serial.print ("I counted for the second Motor ");
//Serial.println (events1);
Serial.print ("the speed (RPM) for Right Motor = ");
Serial.println ((events1/n2)*60000/50);
} // end of showResults
void PID()
{
measuredRightRpm_value=(events0/n1)*(60000/50);//speed in Rpm from Right/encoder/Motor.
erorR= setpoint - measuredRightRpm_value;//Erorr From_Right Encoder.
measuredLeftRpm_value=(events1/n2)*60000/50;////speed in Rpm from Left/encoder/Motor.
erorL= setpoint - measuredLeftRpm_value;////Erorr From_Left Encoder.
}
void loop ()
{
counting = true;
if(flag ==1)
{
showResults();
PID();
events0 = 0;
events1 = 0;
erorR=0;
erorL=0;
flag = 0;
}
OCR0A=192+Kp*erorR; //75% DutyCycle for Right Motor .
OCR0B=192+Kp*erorR;
OCR1A=-192-Kp*erorL;//75% DutyCycle for Left Motor.
OCR1B=-192-Kp*erorL;
} // end of loop
