modelPID_2dof

Digital 2-dof PID controller

Extends from Interfaces.Controller (Partial interface for a digital controller).

Information

Description

Proportional + Integral + Derivative with two degree of freedom controller with Automatic, Tracking, Manual mode and bias signal. The controller is implemented in its incremental form algorithm.
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                  ]

Name	Description	Conditional?
SP	Set Point	NO
PV	Process Variable	NO
CS	Control Signal	NO
satHI	CS at HIGH saturation	NO
satLOW	CS at LOW saturation	NO
TR	Track Reference signal	YES (useTS)
TS	Track Switch signal	YES (useTS)
Bias	Biasing signal	YES (useBIAS)
MAN	Manual Switch signal	YES (useMAN)
CSinc	Control Signal increment	YES (useMAN)
Finc	Forbid increment	YES (useForbid)
Fdec	Forbid decrement	YES (useForbid)

And some of them can be conditionally selected, by specifying a boolean flag.

AntiWindUp mode

If the boolean flag AntiWindup is tue the output of the block ( CS ) saturates at the values specified by CSmin and CSmax.

Tracking mode

If the boolean flag useTS is true, the inputs TS and TR are enabled.
When enabled, if the TS signal is true the output CS is forced to follow the track reference signal TR.

Manual mode

If the boolean flag useMAN is true, the inputs MAN and CSinc are enabled.
When enabled, if the MAN signal is true the output CS can be manually controlled via the signals CSinc and CSdec, that respectively increment or decrement the control signal.

Forbid mode

If the boolean flag useForbid is true, the inputs Finc and Fdec are enabled.
When enabled, if the Finc signal is true the output CS cannot grow up, while if Fdec is true it cannot decrease.

Discretisation

The controller is implemented directly through an algorithm, that represents the discretised version of the continuous time controller.

Parameters

Type	Name	Default	Description
Boolean	useTS (from Controller)	false	=true, if TS and TR inputs are enabled
Boolean	useBIAS (from Controller)	false	=true, if BIAS input is enabled
Boolean	useMAN (from Controller)	false	=true, if MANUAL input is enabled
Boolean	useForbid (from Controller)	false	=true, if Forbid inputs are enabled
Discretisation
Real	Ts (from Controller)	0	Sampling time
Saturation
Boolean	AntiWindup (from Controller)	false	Flag that enables the antiwindup feature
Real	CSmin (from Controller)	0	minimum value of the CS
Real	CSmax (from Controller)	1	maximum value of the CS
Initialisation
Real	CS_start (from Controller)	0	output initial value
Parameters
Real	Kp	1	Gain
Real	Ti	10	Integral time
Real	Td	0	Derivative time
Real	N	5	Derivative filter ratio
Real	b	1	SP weight in P action
Real	c	0	SP weight in D action

Connectors

Type	Name	Description
Modelica.Blocks.Interfaces.RealInput	TR (from Controller)	Track Reference signal
Modelica.Blocks.Interfaces.BooleanInput	TS (from Controller)	Flag that enables the TRACKING mode
Modelica.Blocks.Interfaces.RealInput	BIAS (from Controller)	Bias signal
Modelica.Blocks.Interfaces.BooleanInput	MAN (from Controller)	Flag that enables the MANUAL mode
Modelica.Blocks.Interfaces.RealInput	CSinc (from Controller)	Control Signal increment when MANUAL mode is selected
Modelica.Blocks.Interfaces.BooleanInput	Finc (from Controller)	Flag that forbid an increment of the CS
Modelica.Blocks.Interfaces.BooleanInput	Fdec (from Controller)	Flag that forbid a decrement of the CS
Modelica.Blocks.Interfaces.RealInput	SP (from Controller)	Set Point signal
Modelica.Blocks.Interfaces.RealOutput	CS (from Controller)	Control signal
Modelica.Blocks.Interfaces.RealInput	PV (from Controller)	Process Variable signal
Modelica.Blocks.Interfaces.BooleanOutput	satHI (from Controller)	The CS signal saturated at CSmax
Modelica.Blocks.Interfaces.BooleanOutput	satLOW (from Controller)	The CS signal saturated at CSmin

Components

Type	Name	Description
Real	bias (from Controller)	bias signal
Real	tr (from Controller)	track reference value
Boolean	ts (from Controller)	track reference signal
Real	csInc (from Controller)	control signal increment when man mode is selected
Boolean	man (from Controller)	manual enabling signal
Boolean	F_inc (from Controller)	forbidden increment signal
Boolean	F_dec (from Controller)	forbidden decrement signal

Revisions

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