PID heat Controller with ThermoCouple 16f877

[emre2blue]

Hi I made this project for my 3. class univ project. It uses MAXIM 16 bit ADC, ultra-Low Offset up to 2,5uV Opamp,

PIC16F877 And K-Type thermocouple. It drives a 100w 220v bulb lamp via BT136 triac. Two line LCD is to show

configrations and temperatures. And it uses push buttons to increase or decrease the temperature of the bulb lamp

http://rapidshare.de/files/38375273/Project.II.rar.html

[lutfuakcil]

PID is very common, but it causes overshoot on the process, some controllers uses fuzzy logic + PID algorithm, but i don't have any idea how they are combined ?....:-(

[emre2blue]

I don't know either. I guess FuzzyLogic for heating is come off from PID. and it is a little bit more understandable.

[macitmucit]

did you try it with Lm35 sensor .?

[emre2blue]

Yes I've used LM35 to read K-Type thermoCouple Connection Temperature (Room temperature)
Celc is LM35
Celc1 is from ThermoCouple ( via MAX1133 16bit ADC )

      value1=0;
      for(i=0;i<16;i++)
         value1 = value1 + read_adc(ADC_READ_ONLY);

         value1 = value1 >> 4;      // (value1 / 1024) * 5000 mV / (10 mV / C)

      celc = value1 * 0.488283; //[Volt]

      celc2 = celc+celc1;

[mayler]

I am making a similar project, but it's more critical. I am working with a R type thermocouple ( 6 µV / C ) and I am using an instrumentation amplifier, A/D converter, cold junction compensator and reference voltage. I don't like to put the signal directly in AD, because the instrumentation amplifier has more resources as better CMRR. I need absolute precision in this case. I am making a enchanced PID control with adaptative values for improved response. I suggest that you dont use phase control, because of excessive noise... Make a zero-cross control for better results. 

[klivi1]

PID is very common, but it causes overshoot on the process, some controllers uses fuzzy logic + PID algorithm, but i don't have any idea how they are combined ?....:-(

Hi,

I think the PID algorithm is widely used and stable, if you use good parameters. (I mean no oversoot, and quick setting time).  Combining with fuzzy logic would mean lot of complications and hard to implement in micro.

klivi

[mayler]

If you use adaptative values for constants and use bang bang control, the PID will have an excellent precision... Only need to find the correct parameters for Kp, Kd and Ki. There are many methods, Ziegler–Nichols method is the most common method for finding the constants (auto-tuning can be implemented by it).

[strolch]

Hello,
i atached my PID-Regulator. I think i have copy it from the CSS-Forum and modified it to PICC18.
It works fine.
If you use the dsPIC, there is one delivered by the C30.



union LNG {
   long l;
   unsigned long ul;
   int i[2];
   unsigned int ui[2];
   char b[4];
   unsigned char ub[4];
   };

union LNG

u_error,               // PID error value
u_ypid,               // PID error value
u_integral;               // PID integral value

void U_CalcPID(void)
{
   long limit_i;                                    //limiter for Intergral
      u_integral.l += u_error.l;                             // modify the integral value.
   u_ypid.l = (long)u_error.i[0]*(long)U_KP + u_integral.l*(long)U_KI;   // Calculate the PID compensator.            
   if(u_ypid.ub[3] & 0x80)                              // If PID result is negative
      {
      if((u_ypid.ub[3] < 0xff) || !(u_ypid.ub[2] & 0x80))
      u_ypid.ul = 0xff800000;                           // Limit result to 24-bit value
      }

   else                                          // If PID result is positive
      {
      if(u_ypid.ub[3] || (u_ypid.ub[2] > 0x7f))
      u_ypid.ul = 0x007fffff;                           // Limit result to 24-bit value
      }
   
   u_ypid.b[0] = u_ypid.b[1];                              // Shift PID result right to
   u_ypid.b[1] = u_ypid.b[2];                              // get upper 16 bits.

   u_stat.saturated = 0;                                 // Clear saturation flag and see

   if(u_ypid.i[0] == 32767)                              // if present duty cycle output
      {                                          // exceeds limits.
      u_ypid.i[0] = 32767;
      u_stat.saturated = 1;
      }
   
   if(u_ypid.i[0] < 0)
      {
      u_ypid.i[0] = 0;
      u_stat.saturated = 1;
      }
   limit_i=8388607;
   if(U_KI>0) limit_i/=U_KI;
   limit_i+=1000;   

   u_stat.isaturated = 0;                              // Clear saturation flag and see
   if(u_integral.l >  limit_i)                           // if present duty cycle output
      {                                           // exceeds limits.
      u_integral.l = limit_i;
      u_stat.isaturated = 1;
      }
   limit_i*=(-1);
   if(u_integral.l < limit_i)
      {
      u_integral.l = limit_i;
      u_stat.isaturated = 1;
      }
}

[dreamwithin]

I'm writing a program for thin film coating contral, the thickness were captured every second, can I use your PID algorithm for that.

[muse2001]

I cant get the file from http://rapidshare.de/files/38375273/Project.II.rar.html
Re-Upload please!
File not found

[oldvan]

On a recent project, I found the MAX6675 "12-bit Cold-Junction-Compensated K-Thermocouple to-Digital Converter (0°C to +1024°C)" to be inccredibly helpful.  It includes everything I needed for a K thermocouple in an 8-pin surface-mount package.  Allowed me to be terribly lazy. 

I attached it to a 16F877A, along with a 12-key keypad, a 4X16 LCD and a few other things to form a controller for the furnace in my garage.

I didn't need PID for my project, so have no insights to add there.

[USB123]

Can someone upload it again. It was deleted already.

[lillbear]

Gone...maybe reload on ifile?

yours

[ahmetefegumus]

muse2001 ; could you uploud agan this file at rapidshare? The link is died.

[sadman]

Hi I made this project for my 3. class univ project. It uses MAXIM 16 bit ADC, ultra-Low Offset up to 2,5uV Opamp,

PIC16F877 And K-Type thermocouple. It drives a 100w 220v bulb lamp via BT136 triac. Two line LCD is to show

configrations and temperatures. And it uses push buttons to increase or decrease the temperature of the bulb lamp

http://rapidshare.de/files/38375273/Project.II.rar.html

can you please reupload it

regards
sadman

[arash_tah]

Hi emre2blue 
can u share your file again? The link doesnt work.

[vbcoder]

The Fuzzy PID is a PID controller where its Kp, Ki and Kd values are tuned based on Error and change of the error. This enhances the transient response and minimizes the overshoot since the values mentioned are not constants over the process control when using the fuzzy PID technique.

I only didn't find any aided tools for fuzzy logic code generation or patterns using PIC Microcontrollers. Yes you can create your fuzzy rules and engine easily but it requires lots of time.

Nice project and idea 

[ismail505]

Can anybody reupload this project, please...

[ashu.spect]

emre2blue can you plzz upload the PID project on RS

Thanks in Advance

Ashu

[jlian168]

Dear all:
Does anyone has the project,Please upload to RS link again.

Thank you very much.