WPILibC++ 2023.4.3-108-ge5452e3
frc::PoseEstimator< WheelSpeeds, WheelPositions > Class Template Reference

This class wraps odometry to fuse latency-compensated vision measurements with encoder measurements. More...

#include <frc/estimator/PoseEstimator.h>

Public Member Functions

 PoseEstimator (Kinematics< WheelSpeeds, WheelPositions > &kinematics, Odometry< WheelSpeeds, WheelPositions > &odometry, const wpi::array< double, 3 > &stateStdDevs, const wpi::array< double, 3 > &visionMeasurementStdDevs)
 Constructs a PoseEstimator. More...
 
void SetVisionMeasurementStdDevs (const wpi::array< double, 3 > &visionMeasurementStdDevs)
 Sets the pose estimator's trust in vision measurements. More...
 
void ResetPosition (const Rotation2d &gyroAngle, const WheelPositions &wheelPositions, const Pose2d &pose)
 Resets the robot's position on the field. More...
 
Pose2d GetEstimatedPosition () const
 Gets the estimated robot pose. More...
 
void AddVisionMeasurement (const Pose2d &visionRobotPose, units::second_t timestamp)
 Adds a vision measurement to the Kalman Filter. More...
 
void AddVisionMeasurement (const Pose2d &visionRobotPose, units::second_t timestamp, const wpi::array< double, 3 > &visionMeasurementStdDevs)
 Adds a vision measurement to the Kalman Filter. More...
 
Pose2d Update (const Rotation2d &gyroAngle, const WheelPositions &wheelPositions)
 Updates the pose estimator with wheel encoder and gyro information. More...
 
Pose2d UpdateWithTime (units::second_t currentTime, const Rotation2d &gyroAngle, const WheelPositions &wheelPositions)
 Updates the pose estimator with wheel encoder and gyro information. More...
 

Detailed Description

template<typename WheelSpeeds, WheelPositions WheelPositions>
class frc::PoseEstimator< WheelSpeeds, WheelPositions >

This class wraps odometry to fuse latency-compensated vision measurements with encoder measurements.

Robot code should not use this directly- Instead, use the particular type for your drivetrain (e.g., DifferentialDrivePoseEstimator). It will correct for noisy vision measurements and encoder drift. It is intended to be an easy drop-in for Odometry.

Update() should be called every robot loop.

AddVisionMeasurement() can be called as infrequently as you want; if you never call it, then this class will behave like regular encoder odometry.

Constructor & Destructor Documentation

◆ PoseEstimator()

template<typename WheelSpeeds , WheelPositions WheelPositions>
frc::PoseEstimator< WheelSpeeds, WheelPositions >::PoseEstimator ( Kinematics< WheelSpeeds, WheelPositions > &  kinematics,
Odometry< WheelSpeeds, WheelPositions > &  odometry,
const wpi::array< double, 3 > &  stateStdDevs,
const wpi::array< double, 3 > &  visionMeasurementStdDevs 
)

Constructs a PoseEstimator.

Parameters
kinematicsA correctly-configured kinematics object for your drivetrain.
odometryA correctly-configured odometry object for your drivetrain.
stateStdDevsStandard 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.
visionMeasurementStdDevsStandard 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.

Member Function Documentation

◆ AddVisionMeasurement() [1/2]

template<typename WheelSpeeds , WheelPositions WheelPositions>
void frc::PoseEstimator< WheelSpeeds, WheelPositions >::AddVisionMeasurement ( const Pose2d visionRobotPose,
units::second_t  timestamp 
)

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() 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
visionRobotPoseThe pose of the robot as measured by the vision camera.
timestampThe timestamp of the vision measurement in seconds. Note that if you don't use your own time source by calling UpdateWithTime(), then you must use a timestamp with an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as frc::Timer::GetFPGATimestamp(). This means that you should use frc::Timer::GetFPGATimestamp() as your time source in this case.

◆ AddVisionMeasurement() [2/2]

template<typename WheelSpeeds , WheelPositions WheelPositions>
void frc::PoseEstimator< WheelSpeeds, WheelPositions >::AddVisionMeasurement ( const Pose2d visionRobotPose,
units::second_t  timestamp,
const wpi::array< double, 3 > &  visionMeasurementStdDevs 
)
inline

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() 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() or this method.

Parameters
visionRobotPoseThe pose of the robot as measured by the vision camera.
timestampThe timestamp of the vision measurement in seconds. Note that if you don't use your own time source by calling UpdateWithTime(), then you must use a timestamp with an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as frc::Timer::GetFPGATimestamp(). This means that you should use frc::Timer::GetFPGATimestamp() as your time source in this case.
visionMeasurementStdDevsStandard 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.

◆ GetEstimatedPosition()

template<typename WheelSpeeds , WheelPositions WheelPositions>
Pose2d frc::PoseEstimator< WheelSpeeds, WheelPositions >::GetEstimatedPosition

Gets the estimated robot pose.

Returns
The estimated robot pose in meters.

◆ ResetPosition()

template<typename WheelSpeeds , WheelPositions WheelPositions>
void frc::PoseEstimator< WheelSpeeds, WheelPositions >::ResetPosition ( const Rotation2d gyroAngle,
const WheelPositions &  wheelPositions,
const Pose2d pose 
)

Resets the robot's position on the field.

The gyroscope angle does not need to be reset in the user's robot code. The library automatically takes care of offsetting the gyro angle.

Parameters
gyroAngleThe current gyro angle.
wheelPositionsThe distances traveled by the encoders.
poseThe estimated pose of the robot on the field.

◆ SetVisionMeasurementStdDevs()

template<typename WheelSpeeds , WheelPositions WheelPositions>
void frc::PoseEstimator< WheelSpeeds, WheelPositions >::SetVisionMeasurementStdDevs ( const wpi::array< double, 3 > &  visionMeasurementStdDevs)

Sets the pose estimator's trust in vision 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
visionMeasurementStdDevsStandard 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()

template<typename WheelSpeeds , WheelPositions WheelPositions>
Pose2d frc::PoseEstimator< WheelSpeeds, WheelPositions >::Update ( const Rotation2d gyroAngle,
const WheelPositions &  wheelPositions 
)

Updates the pose estimator with wheel encoder and gyro information.

This should be called every loop.

Parameters
gyroAngleThe current gyro angle.
wheelPositionsThe distances traveled by the encoders.
Returns
The estimated pose of the robot in meters.

◆ UpdateWithTime()

template<typename WheelSpeeds , WheelPositions WheelPositions>
Pose2d frc::PoseEstimator< WheelSpeeds, WheelPositions >::UpdateWithTime ( units::second_t  currentTime,
const Rotation2d gyroAngle,
const WheelPositions &  wheelPositions 
)

Updates the pose estimator with wheel encoder and gyro information.

This should be called every loop.

Parameters
currentTimeThe time at which this method was called.
gyroAngleThe current gyro angle.
wheelPositionsThe distances traveled by the encoders.
Returns
The estimated pose of the robot in meters.

The documentation for this class was generated from the following files: