ptolemy.domains.de.lib
Class PID

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.domains.de.kernel.DEActor
                              ptolemy.domains.de.lib.DETransformer
                                  ptolemy.domains.de.lib.PID

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, SequenceActor, TimedActor, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class PID
extends DETransformer

Generate PID output for a given input. The output is the sum of a proportional gain (P), discrete integration (I), and discrete derivative (D).

The proportional component of the output is immediately available, such that yp[n]=Kp*x[n], where yp is the proportional component of the output, Kp is the proportional gain, and x is the input value.

For integral gain, the output is available after two input symbols have been received, such that yi[n]=Ki*(yi[n-1]+(x[n] + x[n-1]))*dt[n]/2, where yi is the integral component of the output, Ki is the integral gain, and dt[n] is the time differential between input events x[n] and x[n-1].

For derivative gain, the output is available after two input symbols have been received, such that yd[n] = Kd*(x[n]-x[n-1])/dt, where yd is the derivative component of the output, Kd is the derivative gain, and dt is the time differential between input events events x[n] and x[n-1].

The output of this actor is constrained to be a double, and input must be castable to a double. If the input signal is not left-continuous and the derivative constant is nonzero, then this actor will throw an exception as the derivative will be either infinite or undefined. If the derivative constant is zero, then this actor may recieve discontinuous input.

y[0]=Kp*x[0]
y[n] = yp[n] + yi[n] + yd[n]
y[n] = Kp*x[n] + Ki*sum{x=1}{n}{(x[n]+x[n-1])/2*dt[n]} + Kd*(x[n]-x[n-1]/dt[n])

In postfire(), if an event is present on the reset port, this actor resets to its initial state, where integral and derivative components of output will not be present until two subsequent inputs have been consumed. This is useful if the input signal is switched on and off, in which case the time gap between events becomes large and would otherwise effect the value of the derivative (for one sample) and the integral.

Since:

Ptolemy II 8.0

Version:

$Id: PID.java 59203 2010-09-23 21:41:27Z cxh $

Author:

Jeff C. Jensen

See Also:

Integrator, Derivative, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

private DoubleToken	_accumulated
private TimedEvent	_currentInput
private TimedEvent	_lastInput
Parameter	Kd Derivative gain of the controller.
Parameter	Ki Integral gain of the controller.
Parameter	Kp Proportional gain of the controller.
TypedIOPort	reset The reset port, which has undeclared type.

Fields inherited from class ptolemy.domains.de.lib.DETransformer

input, output

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

PID(CompositeEntity container, java.lang.String name)
Construct an actor with the given container and name.

Method Summary

void	attributeChanged(Attribute attribute) If the attribute is Kp, Ki, or Kd then ensure that the value is numeric.
java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Consume at most one token from the input port and output the PID control.
void	initialize() Reset to indicate that no input has yet been seen.
boolean	postfire() Record the most recent input as the latest input.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, prefire, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate, wrapup

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface ptolemy.actor.Actor

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, prefire, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable, wrapup

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

reset

public TypedIOPort reset

The reset port, which has undeclared type. If this port receives a token, this actor resets to its initial state, and no output is generated until two inputs have been received.

Kp

public Parameter Kp

Proportional gain of the controller. Default value is 1.0.

Ki

public Parameter Ki

Integral gain of the controller. Default value is 0.0, which disables integral control.

Kd

public Parameter Kd

Derivative gain of the controller. Default value is 0.0, which disables derivative control. If Kd=0.0, this actor can receive discontinuous signals as input; otherwise, if Kd is nonzero and a discontinuous signal is received, an exception will be thrown.

_currentInput

private TimedEvent _currentInput

_lastInput

private TimedEvent _lastInput

_accumulated

private DoubleToken _accumulated

Constructor Detail

PID

public PID(CompositeEntity container,
           java.lang.String name)
    throws NameDuplicationException,
           IllegalActionException

Construct an actor with the given container and name.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the actor cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

clone

public java.lang.Object clone(Workspace workspace)
                       throws java.lang.CloneNotSupportedException

Clone the actor into the specified workspace. This calls the base class and then sets the ports.

Overrides:

clone in class AtomicActor

Parameters:

workspace - The workspace for the new object.

Returns:

A new actor.

Throws:

java.lang.CloneNotSupportedException - If a derived class has has an attribute that cannot be cloned.

See Also:

NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the attribute is Kp, Ki, or Kd then ensure that the value is numeric.

Overrides:

attributeChanged in class NamedObj

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If the value is non-numeric.

initialize

public void initialize()
                throws IllegalActionException

Reset to indicate that no input has yet been seen.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If the parent class throws it.

fire

public void fire()
          throws IllegalActionException

Consume at most one token from the input port and output the PID control. If there has been no previous iteration, only proportional output is generated. If there is no input, then produce no output.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If addition, multiplication, subtraction, or division is not supported by the supplied tokens.

postfire

public boolean postfire()
                 throws IllegalActionException

Record the most recent input as the latest input. If a reset event has been received, process it here.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - If the base class throws it.