.IndustrialControlSystems.Controllers.PID

Proportional + Integral + Derivative two degree of freedom controller

Information

Description

Proportional + Integral + Derivative with two degree of freedom controller with Automatic, Tracking mode and bias signal.
The control law is defined as

            [                      1                        sTd                      ]
  CS(s) = Kp[ (bSP(s) - PV(s)) + ----- (SP(s) - PV(S)) + -----------(cSP(s) - PV(s)) ]
            [                     sTi                     1 + sTd/N                  ]

Scheme

Name	Description	Conditional?
SP	Set Point	NO
PV	Process Variable	NO
CS	Control Signal	NO
TR	Track Reference signal	YES (useTS)
TS	Track Switch signal	YES (useTS)
Bias	Biasing signal	YES (useBIAS)
ATreq	AutoTuning request	YES (*)

(*) AutoTuning Not available here, please see the package
AutoTuning

The controller can have various operating conditions:

Automatic,
and Tracking

In the Automatic mode, the control output is computed with the integral control law, while in the tracking mode
it is defined by the input TR.

To note that in the tracking mode the output of the integral block is forced to follow the track reference

              1
  I(s) = ---------- TR(S)
           1+s*eps

where eps is a small time constant. Thanks to such a scheme, the integrator does not diverge while the tracking mode
is enabled.

Revisions

Industrial Control Systems (v 1.0.0) : April-May 2012