PIDControl

java.lang.Object
- util.PropertyContainer
- - util.PIDControl

All Implemented Interfaces:

Cloneable, PropertySupplying
```
public class PIDControl
extends PropertyContainer
```
PID (Proportional-Integral-Differential) Controllers are basic applications in servo motor controls. If the difference between nominal and actual is denoted as an error e(t), the output of the PID controller, i.e. the required correction c(t) can be writtn as:
```
 c(t)=kp·e(t)+ki·∫e(t)dt+kd·de(t)/dt
 
```
The name PID comes from these three proportional constant, that are related to the signal itself, its integral, respectively differential with time. Determining the values of this three parameter is some science on its own.
This class allows basic access to PID-control. It allows registering of an Integrator and Differentiator. The three constants are provided in the PIDControl's properties. Calling the getCorrection() method evaluates the formular above and returns the c(t).

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class PIDControl.Test
Test string representation.

Nested Classes
Modifier and Type	Class and Description
`static class`	`PIDControl.Test` Test string representation.

Field Summary

Fields
Modifier and Type	Field and Description
`private static double`	`DEFDIFFERENTIAL` The default value of the differential constant.
`private static Class`	`DEFDIFFERENTIATOR` The default differentiator class .
`private static double`	`DEFINTEGRAL` The default value of the integral constant.
`private static Class`	`DEFINTEGRATOR` The default integrator class .
`private static double`	`DEFLIMIT` The default limit, zero=no limit.
`private static double`	`DEFPROPORTIONAL` The default value of the proportional constant.
`private Differentiator`	`differentiate` The differentiator to use.
`private boolean`	`initialized` True after the first error has been added.
`private Integrator`	`integrate` The integrator to use.
`static String`	`KEY_DIFFERENTIAL` The differential constant.
`static String`	`KEY_DIFFERENTIATOR` The class name of the differentiator.
`static String`	`KEY_INTEGRAL` The integral constant.
`static String`	`KEY_INTEGRATOR` The class name of the integrator.
`static String`	`KEY_LIMIT` The PID correction limit.
`static String`	`KEY_PROPORTIONAL` The proportional constant.
`private double`	`lastoffset` The last offset added, used for the proportional term.

Fields inherited from class util.PropertyContainer
KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.PropertySupplying
CONFIG, KEY_CLASS

Constructor Summary

Constructors
Constructor and Description
`PIDControl(Map<String,String> info)` Constructs a new PID-control.
`PIDControl(String pid)` Convenience constructor allowing instantiation with a string like

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addError(double offset)` Adds an error signal in the equal time-step case.
`void`	`addError(double t, double offset)` Adds an error signal with a varying time-step.
`void`	`clear()` Clears the PID and allows for a new run.
`double`	`getCorrection()` Returns the correction to the signal as derived from previous offsets.
`double`	`getDifferential()` Sets the differential term.
`double`	`getIntegral()` Sets the integral term.
`double`	`getProportional()` Gets the proportinal term.
`private static boolean`	`searchDouble(String key1, String keyset, Map<String,String> search, PropertySupplying where)` Searches the map for a string representation of the key in the first argument, tries to convert this to a double and set this as the second string property in the property container.
`void`	`setDifferential(double diff)` Sets the differential term.
`void`	`setIntegral(double integral)` Sets the integral term.
`void`	`setProportional(double prop)` Sets the proportinal term.
`String`	`toString()` Returns the three main parameters of the pid as a string.

Methods inherited from class util.PropertyContainer
augment, augment, augment, augment, augment, clone, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, initProperties, isNew, parseObject, parseObject, reload, reload, removeProperty, requires, rescanned, setObject, setProperties, setProperty, stringProperties

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - KEY_PROPORTIONAL
```
public static final String KEY_PROPORTIONAL
```
    The proportional constant.
    
    See Also:
    
    Constant Field Values
  - KEY_DIFFERENTIAL
```
public static final String KEY_DIFFERENTIAL
```
    The differential constant.
    
    See Also:
    
    Constant Field Values
  - KEY_INTEGRAL
```
public static final String KEY_INTEGRAL
```
    The integral constant.
    
    See Also:
    
    Constant Field Values
  - KEY_LIMIT
```
public static final String KEY_LIMIT
```
    The PID correction limit. Corrections exceeding this are truncated.
    
    See Also:
    
    Constant Field Values
  - KEY_INTEGRATOR
```
public static final String KEY_INTEGRATOR
```
    The class name of the integrator.
    
    See Also:
    
    Constant Field Values
  - KEY_DIFFERENTIATOR
```
public static final String KEY_DIFFERENTIATOR
```
    The class name of the differentiator.
    
    See Also:
    
    Constant Field Values
  - DEFPROPORTIONAL
```
private static final double DEFPROPORTIONAL
```
    The default value of the proportional constant.
    
    See Also:
    
    Constant Field Values
  - DEFDIFFERENTIAL
```
private static final double DEFDIFFERENTIAL
```
    The default value of the differential constant.
    
    See Also:
    
    Constant Field Values
  - DEFINTEGRAL
```
private static final double DEFINTEGRAL
```
    The default value of the integral constant.
    
    See Also:
    
    Constant Field Values
  - DEFLIMIT
```
private static final double DEFLIMIT
```
    The default limit, zero=no limit.
    
    See Also:
    
    Constant Field Values
  - DEFINTEGRATOR
```
private static final Class DEFINTEGRATOR
```
    The default integrator class .
  - DEFDIFFERENTIATOR
```
private static final Class DEFDIFFERENTIATOR
```
    The default differentiator class .
  - lastoffset
```
private double lastoffset
```
    The last offset added, used for the proportional term.
  - integrate
```
private Integrator integrate
```
    The integrator to use.
  - differentiate
```
private Differentiator differentiate
```
    The differentiator to use.
  - initialized
```
private boolean initialized
```
    True after the first error has been added.
- Constructor Detail
  - PIDControl
```
public PIDControl(String pid)
```
    Convenience constructor allowing instantiation with a string like
```
 P=0.5:I=0.2:D=0.0:L=20.
 
```
  - PIDControl
```
public PIDControl(Map<String,String> info)
```
    Constructs a new PID-control. It is the user's responsibility to not call the getCorrection() method before enough differences had been added with addError(double) for the integrator/differentiator to work. Additionally, the user must be aware that the integrator/ differentiator supplied in the properties is compliant with the addError(double) method used, i.e. whether a fixed time-step or a (error-t) pair is used.
- Method Detail
  - searchDouble
```
private static final boolean searchDouble(String key1,
                                          String keyset,
                                          Map<String,String> search,
                                          PropertySupplying where)
```
    Searches the map for a string representation of the key in the first argument, tries to convert this to a double and set this as the second string property in the property container.
    
    Returns:
    
    True, if double was entered.
  - addError
```
public void addError(double offset)
```
    Adds an error signal in the equal time-step case. It is the users responsibility to supply an integrator/differntiator that can work with equal step-size integration/differentiation. The default integrator and differentiator can only work with this method.
  - clear
```
public void clear()
```
    Clears the PID and allows for a new run.
  - addError
```
public void addError(double t,
                     double offset)
```
    Adds an error signal with a varying time-step. It is the users responsibility to supply an integrator/differntiator that can work with non-equal step-size integration/differentiation. The default integrator and differentiator can not work with this method.
  - getCorrection
```
public double getCorrection()
```
    Returns the correction to the signal as derived from previous offsets. May not be called prior to adding enough offsets using the addError(double) method.
  - getProportional
```
public double getProportional()
```
    Gets the proportinal term.
  - setProportional
```
public void setProportional(double prop)
```
    Sets the proportinal term.
  - getDifferential
```
public double getDifferential()
```
    Sets the differential term.
  - setDifferential
```
public void setDifferential(double diff)
```
    Sets the differential term.
  - getIntegral
```
public double getIntegral()
```
    Sets the integral term.
  - setIntegral
```
public void setIntegral(double integral)
```
    Sets the integral term.
  - toString
```
public String toString()
```
    Returns the three main parameters of the pid as a string.
    
    Overrides:
    
    toString in class PropertyContainer

Class PIDControl

Nested Class Summary

Field Summary

Fields inherited from class util.PropertyContainer

Fields inherited from interface util.PropertySupplying

Constructor Summary

Method Summary

Methods inherited from class util.PropertyContainer

Methods inherited from class java.lang.Object

Field Detail

KEY_PROPORTIONAL

KEY_DIFFERENTIAL

KEY_INTEGRAL

KEY_LIMIT

KEY_INTEGRATOR

KEY_DIFFERENTIATOR

DEFPROPORTIONAL

DEFDIFFERENTIAL

DEFINTEGRAL

DEFLIMIT

DEFINTEGRATOR

DEFDIFFERENTIATOR

lastoffset

integrate

differentiate

initialized

Constructor Detail

PIDControl

PIDControl

Method Detail

searchDouble

addError

clear

addError

getCorrection

getProportional

setProportional

getDifferential

setDifferential

getIntegral

setIntegral

toString