org.lsst.ccs.subsystem.common

Class PIController

java.lang.Object

org.lsst.ccs.subsystem.common.PIController

public class PIController
extends Object

Class: PI_Controller.java; Proportional, Integral controller

Description: This PI_Controller class implements a proportional, integral feedback loop controller for use in the thermal control of the LSST camera electronics. The functionality includes anti-windup.

Author:

Innes

Constructor Summary

Constructors

Constructor and Description
PIController(double Init_gain, double Init_timeConstant) Allocate a PI object with the given constants for P, I

Method Summary

Modifier and Type	Method and Description
double	getError() Returns the current difference of the input from the setpoint
double	getI() Get the Integral coefficient
double	getIntegral() Returns the current error integral
double	getP() Get the Proportional coefficient
double	getSetpoint() Returns the current setpoint of the PIDController
double	getSmooth() Returns the current smoothed input
boolean	onTarget() Return true if the error is within the percentage of the input range, determined by setTolerance.
double	performPI(double[] input, double time) Return the current PI result.
void	reset() Reset the previous error, the integral, and disable the controller.
void	setAwGain(double gain) Sets the anti-windup gain.
void	setBaseOutput(double value) Sets the base output.
void	setInputRange(double minimumInput, double maximumInput) Sets the maximum and minimum values expected from the input.
void	setIntegral(double value) Sets the error integral
void	setOutputRange(double minimumOutput, double maximumOutput) Sets the minimum and maximum values to write.
void	setPID(double p, double intTime) Set the PI Controller gain parameters.
void	setSetpoint(double setpnt) Set the setpoint for the PIDController
void	setSmoothTime(double time) Sets the smoothing time.
void	setTolerance(double percent) Set the percentage error which is considered tolerable for use with OnTarget.

Methods inherited from class java.lang.Object

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

Constructor Detail

PIController

public PIController(double Init_gain,
                    double Init_timeConstant)

Allocate a PI object with the given constants for P, I

Parameters:

Init_gain - the loop gain coefficient

Init_timeConstant - the integration time constant (seconds)

Method Detail

performPI

public double performPI(double[] input,
                        double time)

Return the current PI result. This is constrained by the max and min outs

Parameters:

input - The array of input values

time - The measurement time

Returns:

the latest calculated output

setPID

public void setPID(double p,
                   double intTime)

Set the PI Controller gain parameters. Set the proportional, integral, and differential coefficients.

Parameters:

p - Proportional coefficient (overall loop gain)

intTime - Integral coefficient (integration time constant)

getP

public double getP()

Get the Proportional coefficient

Returns:

proportional coefficient

getI

public double getI()

Get the Integral coefficient

Returns:

integral coefficient

setSmoothTime

public void setSmoothTime(double time)

Sets the smoothing time.

Parameters:

time - the smoothing time

setAwGain

public void setAwGain(double gain)

Sets the anti-windup gain.

Parameters:

gain - the anti-windup gain

setBaseOutput

public void setBaseOutput(double value)

Sets the base output.

Parameters:

value - the base output value

setTolerance

public void setTolerance(double percent)

Set the percentage error which is considered tolerable for use with OnTarget. (Input of 15.0 = 15 percent)

Parameters:

percent - error which is tolerable

setInputRange

public void setInputRange(double minimumInput,
                          double maximumInput)

Sets the maximum and minimum values expected from the input.

Parameters:

minimumInput - the minimum value expected from the input

maximumInput - the maximum value expected from the output

setOutputRange

public void setOutputRange(double minimumOutput,
                           double maximumOutput)

Sets the minimum and maximum values to write.

Parameters:

minimumOutput - the minimum value to write to the output

maximumOutput - the maximum value to write to the output

setSetpoint

public void setSetpoint(double setpnt)

Set the setpoint for the PIDController

Parameters:

setpnt - the desired setpoint

getSetpoint

public double getSetpoint()

Returns the current setpoint of the PIDController

Returns:

the current setpoint

getError

public double getError()

Returns the current difference of the input from the setpoint

Returns:

the current error

getIntegral

public double getIntegral()

Returns the current error integral

Returns:

the current error integral

setIntegral

public void setIntegral(double value)

Sets the error integral

Parameters:

value - the error integral value to set

getSmooth

public double getSmooth()

Returns the current smoothed input

Returns:

the current smoothed input

onTarget

public boolean onTarget()

Return true if the error is within the percentage of the input range, determined by setTolerance. This assumes that the maximum and minimum input were set using setInput.

Returns:

true if the error is less than the tolerance

reset

public void reset()

Reset the previous error, the integral, and disable the controller.