Class PoseEstimator<T extends WheelPositions<T>>
 Direct Known Subclasses:
DifferentialDrivePoseEstimator
,MecanumDrivePoseEstimator
,SwerveDrivePoseEstimator
public class PoseEstimator<T extends WheelPositions<T>> extends Object
Odometry
to fuse latencycompensated vision measurements with encoder
measurements. Robot code should not use this directly Instead, use the particular type for your
drivetrain (e.g., DifferentialDrivePoseEstimator
). It is intended to be a dropin
replacement for Odometry
; in fact, if you never call addVisionMeasurement(edu.wpi.first.math.geometry.Pose2d, double)
and only call update(edu.wpi.first.math.geometry.Rotation2d, T)
then this will
behave exactly the same as Odometry.
update(edu.wpi.first.math.geometry.Rotation2d, T)
should be called every robot loop.
addVisionMeasurement(edu.wpi.first.math.geometry.Pose2d, double)
can be called as infrequently as you want; if you
never call it then this class will behave exactly like regular encoder odometry.

Constructor Summary

Method Summary
Modifier and Type Method Description void
addVisionMeasurement(Pose2d visionRobotPoseMeters, double timestampSeconds)
Adds a vision measurement to the Kalman Filter.void
addVisionMeasurement(Pose2d visionRobotPoseMeters, double timestampSeconds, Matrix<N3,N1> visionMeasurementStdDevs)
Adds a vision measurement to the Kalman Filter.Pose2d
getEstimatedPosition()
Gets the estimated robot pose.void
resetPosition(Rotation2d gyroAngle, T wheelPositions, Pose2d poseMeters)
Resets the robot's position on the field.void
setVisionMeasurementStdDevs(Matrix<N3,N1> visionMeasurementStdDevs)
Sets the pose estimator's trust of global measurements.Pose2d
update(Rotation2d gyroAngle, T wheelPositions)
Updates the pose estimator with wheel encoder and gyro information.Pose2d
updateWithTime(double currentTimeSeconds, Rotation2d gyroAngle, T wheelPositions)
Updates the pose estimator with wheel encoder and gyro information.

Constructor Details

PoseEstimator
public PoseEstimator(Kinematics<?,T> kinematics, Odometry<T> odometry, Matrix<N3,N1> stateStdDevs, Matrix<N3,N1> visionMeasurementStdDevs)Constructs a PoseEstimator. Parameters:
kinematics
 A correctlyconfigured kinematics object for your drivetrain.odometry
 A correctlyconfigured odometry object for your drivetrain.stateStdDevs
 Standard deviations of the pose estimate (x position in meters, y position in meters, and heading in radians). Increase these numbers to trust your state estimate less.visionMeasurementStdDevs
 Standard deviations of the vision pose measurement (x position in meters, y position in meters, and heading in radians). Increase these numbers to trust the vision pose measurement less.


Method Details

setVisionMeasurementStdDevs
Sets the pose estimator's trust of global measurements. This might be used to change trust in vision measurements after the autonomous period, or to change trust as distance to a vision target increases. Parameters:
visionMeasurementStdDevs
 Standard deviations of the vision measurements. Increase these numbers to trust global measurements from vision less. This matrix is in the form [x, y, theta]ᵀ, with units in meters and radians.

resetPosition
Resets the robot's position on the field.The gyroscope angle does not need to be reset here on the user's robot code. The library automatically takes care of offsetting the gyro angle.
 Parameters:
gyroAngle
 The angle reported by the gyroscope.wheelPositions
 The current encoder readings.poseMeters
 The position on the field that your robot is at.

getEstimatedPosition
Gets the estimated robot pose. Returns:
 The estimated robot pose in meters.

addVisionMeasurement
Adds a vision measurement to the Kalman Filter. This will correct the odometry pose estimate while still accounting for measurement noise.This method can be called as infrequently as you want, as long as you are calling
update(edu.wpi.first.math.geometry.Rotation2d, T)
every loop.To promote stability of the pose estimate and make it robust to bad vision data, we recommend only adding vision measurements that are already within one meter or so of the current pose estimate.
 Parameters:
visionRobotPoseMeters
 The pose of the robot as measured by the vision camera.timestampSeconds
 The timestamp of the vision measurement in seconds. Note that if you don't use your own time source by callingupdateWithTime(double,Rotation2d,WheelPositions)
then you must use a timestamp with an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch asTimer.getFPGATimestamp()
.) This means that you should useTimer.getFPGATimestamp()
as your time source or sync the epochs.

addVisionMeasurement
public void addVisionMeasurement(Pose2d visionRobotPoseMeters, double timestampSeconds, Matrix<N3,N1> visionMeasurementStdDevs)Adds a vision measurement to the Kalman Filter. This will correct the odometry pose estimate while still accounting for measurement noise.This method can be called as infrequently as you want, as long as you are calling
update(edu.wpi.first.math.geometry.Rotation2d, T)
every loop.To promote stability of the pose estimate and make it robust to bad vision data, we recommend only adding vision measurements that are already within one meter or so of the current pose estimate.
Note that the vision measurement standard deviations passed into this method will continue to apply to future measurements until a subsequent call to
setVisionMeasurementStdDevs(Matrix)
or this method. Parameters:
visionRobotPoseMeters
 The pose of the robot as measured by the vision camera.timestampSeconds
 The timestamp of the vision measurement in seconds. Note that if you don't use your own time source by callingupdateWithTime(double, edu.wpi.first.math.geometry.Rotation2d, T)
, then you must use a timestamp with an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch asTimer.getFPGATimestamp()
). This means that you should useTimer.getFPGATimestamp()
as your time source in this case.visionMeasurementStdDevs
 Standard deviations of the vision pose measurement (x position in meters, y position in meters, and heading in radians). Increase these numbers to trust the vision pose measurement less.

update
Updates the pose estimator with wheel encoder and gyro information. This should be called every loop. Parameters:
gyroAngle
 The current gyro angle.wheelPositions
 The current encoder readings. Returns:
 The estimated pose of the robot in meters.

updateWithTime
Updates the pose estimator with wheel encoder and gyro information. This should be called every loop. Parameters:
currentTimeSeconds
 Time at which this method was called, in seconds.gyroAngle
 The current gyro angle.wheelPositions
 The current encoder readings. Returns:
 The estimated pose of the robot in meters.
