I'm working on a project at Polytechnic, University of Yaounde, CAMEROON. The topic goes thus

ROOT-LOCUS BASED DESIGN AND DIGITAL IMPLEMENTATION OF A PID CONTROLLER FOR A SERVOMECHANISM

I'll be glad for any useful contribution or suggestion

 

<P>Pv=process variable
<BR>Sp=setpoint
<BR>where E=Pv-Sp for forward action and E=Sp-Pv for reverse acting.
<BR>Cv=controlled variable

<PRE>
/t dE
Cv = Kp*E + Ki | Edt + Kd ----
/t0 dt

^integration (in case text construct symbol doesn't look quite right.)

</PRE>
<P>This is just one of many variants of the equation. A digital implementation is not
difficult. Use a summation for the integration. The controller equation must be executed on a consistent time base. Watch out for windup, or the tendency of the integral term to become large over time. A simple way is to limit the integral
result so that 0% < (integral result) < 100%.</P>