PID

[naj_rit]

I DONT HAVE SPECIAL PID VI WITH ME CAN ANY BODY HELP WITH THE IMPLEMENTATION OF PID WIT LABVIEW BASIC BLOCKS

[naj_rit]

my aim is sensor less speed control of dc motor using labview for which pid is a must.so please help me with a basic pid block diagram for motor speed control using basic labview blocks.And i dont have a pid tool kit with me

[BillMe]

I bought the Control kit for my project. It was well worth the money as it took me about 20 mins to get a well behaved closed loop working and most of that time was spent finding the right gains (using  the Ziegler-Nichols tuning method).

And if your system is "sensorless", what are you going to use for your process variable?


Message Edited by Bill@NGC on 02-09-2008 01:32 PM

[naj_rit]

Thanks for ur concern,
                but we dont have  a control kit with us ,only the basic ni elvis module.And how much did the control kit cost for u?
in  our case we r planning to feed back the motor back emf as the process varible for close loop speed control.  and could u help us with the implementation of speed control pid using basic labview,especially with the tunig..Atleast share the algorithm and just check out my pid implemented using mathscript written in matlab and help me with the tuning.

Tc=0,01;
C_prop=0;
C_der=0;
C_int=0;
C_der1=0;
C_int1=0;
err0=0;
err1=0;
setpoint=Rif;
err1=err0
C_der1=C_der;
C_int1=C_int;
err0=(setpoint-gradi);
C_prop=(Kp*err0);
C_der=((tau_d/(tau_d+N*Tc))*C_der1)+(((Kp*tau_d*N)/(tau_d+N*Tc))*(err0-err1));
C_int=C_int1+((Kp*Tc)/tau_i)*err1;
equPID=C_prop+C_der+C_int;
if equPID>4.9
   equPID=4.9
  C_int=C_int1
elseif equPID<0.2
   equPID=0.2
   C_int=C_int1
end
  



Message Edited by naj_rit on 02-10-2008 11:07 AM

[BillMe]

Read this paper on PID tuning, worked for me.

[Nathan_R]

Hi naj-rit,

The Developer Zone article PID Theory Explained contains a basic explanation of the PID algorithm and tuning theory. I found this article by searching the NI website for “PID tuning”. Also the Wikipedia article on PID controllers has a lot of useful information. Both of these articles explain the Ziegler-Nichols tuning method. Use this method as a starting point to tuning your PID system and then you can fine tune it by hand. The Wikipedia article has a table which explains the effects of increasing each gain parameter.

The PID Control Toolkit includes VIs that do PID control. However, you can create your own PID algorithm in LabVIEW. Another option since you already have PID code in mathscript is to use a mathscipt node in LabVIEW. This will let you run your existing mathscript PID code. If you are unfamiliar with the mathscript node the Developer Zone article Developing Algorithms Using LabVIEW MathScript: Part 1 – The LabVIEW MathScript Node is a good place to start.

Regards,
Nathan

[iam]

hi friends

can someone plz help me oyt with PID algo.i dont ve PID toolkit .hw do i go about with I and D controllers.

thanks in advance

[chris.b]

Hello iam,

If you would like to create a PID control without the kit, you would first need to understand how the each of the terms are calculated.  The Dev Zone article PID
Theory Explained and the Wikipedia article on PID
controllers both explain how these terms are calculated.

After you have an understanding of how the parameters are calculated, you can use the Integration and Differentiation palette (Functions » Mathematics » Integration and Differentiation) to calculate the I and D terms.