edu.wpi.first.wpilibj

Class Gyro

java.lang.Object

edu.wpi.first.wpilibj.SensorBase

edu.wpi.first.wpilibj.Gyro

All Implemented Interfaces:

LiveWindowSendable, PIDSource, Sendable

public class Gyro
extends SensorBase
implements PIDSource, LiveWindowSendable

Use a rate gyro to return the robots heading relative to a starting position. The Gyro class tracks the robots heading based on the starting position. As the robot rotates the new heading is computed by integrating the rate of rotation returned by the sensor. When the class is instantiated, it does a short calibration routine where it samples the gyro while at rest to determine the default offset. This is subtracted from each sample to determine the heading.

Nested Class Summary

Nested classes/interfaces inherited from interface edu.wpi.first.wpilibj.PIDSource

PIDSource.PIDSourceParameter

Field Summary

Fields

Modifier and Type	Field and Description
protected AnalogInput	m_analog

Fields inherited from class edu.wpi.first.wpilibj.SensorBase

kAnalogInputChannels, kAnalogOutputChannels, kDigitalChannels, kPDPChannels, kPwmChannels, kRelayChannels, kSolenoidChannels, kSolenoidModules, kSystemClockTicksPerMicrosecond

Constructor Summary

Constructors

Constructor and Description
Gyro(AnalogInput channel) Gyro constructor with a precreated analog channel object.
Gyro(int channel) Gyro constructor using the channel number

Method Summary

Modifier and Type	Method and Description
void	free() Delete (free) the accumulator and the analog components used for the gyro.
double	getAngle() Return the actual angle in degrees that the robot is currently facing.
double	getRate() Return the rate of rotation of the gyro The rate is based on the most recent reading of the gyro analog value
java.lang.String	getSmartDashboardType()
ITable	getTable()
void	initGyro() Initialize the gyro.
void	initTable(ITable subtable) Initializes a table for this sendable object.
double	pidGet() Get the output of the gyro for use with PIDControllers.
void	reset() Reset the gyro.
void	setPIDSourceParameter(PIDSource.PIDSourceParameter pidSource) Set which parameter of the gyro you are using as a process control variable.
void	setSensitivity(double voltsPerDegreePerSecond) Set the gyro sensitivity.
void	startLiveWindowMode() Start having this sendable object automatically respond to value changes reflect the value on the table.
void	stopLiveWindowMode() Stop having this sendable object automatically respond to value changes.
void	updateTable() Update the table for this sendable object with the latest values.

Methods inherited from class edu.wpi.first.wpilibj.SensorBase

checkAnalogInputChannel, checkAnalogOutputChannel, checkDigitalChannel, checkPDPChannel, checkPWMChannel, checkRelayChannel, checkSolenoidChannel, checkSolenoidModule, getDefaultSolenoidModule, setDefaultSolenoidModule

Methods inherited from class java.lang.Object

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

Field Detail

m_analog

protected AnalogInput m_analog

Constructor Detail

Gyro

public Gyro(int channel)

Gyro constructor using the channel number

Parameters:

channel - The analog channel the gyro is connected to. Gyros can only be used on on-board channels 0-1.

Gyro

public Gyro(AnalogInput channel)

Gyro constructor with a precreated analog channel object. Use this constructor when the analog channel needs to be shared.

Parameters:

channel - The AnalogInput object that the gyro is connected to. Gyros can only be used on on-board channels 0-1.

Method Detail

initGyro

public void initGyro()

Initialize the gyro. Calibrate the gyro by running for a number of samples and computing the center value. Then use the center value as the Accumulator center value for subsequent measurements. It's important to make sure that the robot is not moving while the centering calculations are in progress, this is typically done when the robot is first turned on while it's sitting at rest before the competition starts.

reset

public void reset()

Reset the gyro. Resets the gyro to a heading of zero. This can be used if there is significant drift in the gyro and it needs to be recalibrated after it has been running.

free

public void free()

Delete (free) the accumulator and the analog components used for the gyro.

Overrides:

free in class SensorBase

getAngle

public double getAngle()

Return the actual angle in degrees that the robot is currently facing. The angle is based on the current accumulator value corrected by the oversampling rate, the gyro type and the A/D calibration values. The angle is continuous, that is it will continue from 360 to 361 degrees. This allows algorithms that wouldn't want to see a discontinuity in the gyro output as it sweeps past from 360 to 0 on the second time around.

Returns:

the current heading of the robot in degrees. This heading is based on integration of the returned rate from the gyro.

getRate

public double getRate()

Return the rate of rotation of the gyro The rate is based on the most recent reading of the gyro analog value

Returns:

the current rate in degrees per second

setSensitivity

public void setSensitivity(double voltsPerDegreePerSecond)

Set the gyro sensitivity. This takes the number of volts/degree/second sensitivity of the gyro and uses it in subsequent calculations to allow the code to work with multiple gyros. This value is typically found in the gyro datasheet.

Parameters:

voltsPerDegreePerSecond - The sensitivity in Volts/degree/second.

setPIDSourceParameter

public void setPIDSourceParameter(PIDSource.PIDSourceParameter pidSource)

Set which parameter of the gyro you are using as a process control variable. The Gyro class supports the rate and angle parameters

Parameters:

pidSource - An enum to select the parameter.

pidGet

public double pidGet()

Get the output of the gyro for use with PIDControllers. May be the angle or rate depending on the set PIDSourceParameter

Specified by:

pidGet in interface PIDSource

Returns:

the output according to the gyro

getSmartDashboardType

public java.lang.String getSmartDashboardType()

Specified by:

getSmartDashboardType in interface Sendable

Returns:

the string representation of the named data type that will be used by the smart dashboard for this sendable

initTable

public void initTable(ITable subtable)

Initializes a table for this sendable object.

Specified by:

initTable in interface Sendable

Parameters:

subtable - The table to put the values in.

getTable

public ITable getTable()

Specified by:

getTable in interface Sendable

Returns:

the table that is currently associated with the sendable

updateTable

public void updateTable()

Update the table for this sendable object with the latest values.

Specified by:

updateTable in interface LiveWindowSendable

startLiveWindowMode

public void startLiveWindowMode()

Start having this sendable object automatically respond to value changes reflect the value on the table.

Specified by:

startLiveWindowMode in interface LiveWindowSendable

stopLiveWindowMode

public void stopLiveWindowMode()

Stop having this sendable object automatically respond to value changes.

Specified by:

stopLiveWindowMode in interface LiveWindowSendable