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[drive] Add custom weighted twist pose estimator
Currently we just weight drive measurements to 1 so this should be basically the same as what we had before. Signed-off-by: Jade Turner <[email protected]>
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151 changes: 151 additions & 0 deletions
151
src/main/java/org/curtinfrc/frc2025/subsystems/drive/PoseEstimator.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,151 @@ | ||
| package org.curtinfrc.frc2025.subsystems.drive; | ||
|
|
||
| import edu.wpi.first.math.Vector; | ||
| import edu.wpi.first.math.geometry.Pose2d; | ||
| import edu.wpi.first.math.geometry.Rotation2d; | ||
| import edu.wpi.first.math.geometry.Twist2d; | ||
| import edu.wpi.first.math.kinematics.SwerveDriveKinematics; | ||
| import edu.wpi.first.math.kinematics.SwerveModulePosition; | ||
| import edu.wpi.first.math.numbers.N3; | ||
| import edu.wpi.first.wpilibj.RobotController; | ||
| import java.util.LinkedList; | ||
| import java.util.OptionalInt; | ||
| import org.littletonrobotics.junction.Logger; | ||
|
|
||
| public class PoseEstimator { | ||
| private static final double kMaxSampleAge = 0.3; | ||
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| private final class TimestampedTwist2d extends Twist2d { | ||
| public final double timestamp; | ||
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| public TimestampedTwist2d(double dx, double dy, double dtheta, double timestamp) { | ||
| super(dx, dy, dtheta); | ||
| this.timestamp = timestamp; | ||
| } | ||
| } | ||
|
|
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| private final LinkedList<TimestampedTwist2d> samples = new LinkedList<>(); | ||
| private Pose2d rootPose = new Pose2d(); | ||
| private final SwerveModulePosition[] prevWheelPositions; | ||
| private final SwerveDriveKinematics kinematics; | ||
| private Rotation2d gyroOffset; | ||
| private Rotation2d prevAngle; | ||
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|
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| public PoseEstimator( | ||
| SwerveDriveKinematics kinematics, | ||
| SwerveModulePosition[] wheelPositions, | ||
| Rotation2d gyroAngle) { | ||
| this.kinematics = kinematics; | ||
| prevWheelPositions = kinematics.copy(wheelPositions); | ||
| gyroOffset = rootPose.getRotation().minus(gyroAngle); | ||
| prevAngle = rootPose.getRotation(); | ||
| } | ||
|
|
||
| public void resetPosition( | ||
| Rotation2d gyroAngle, SwerveModulePosition[] wheelPositions, Pose2d pose) { | ||
| rootPose = pose; | ||
| prevAngle = pose.getRotation(); | ||
| gyroOffset = pose.getRotation().minus(gyroAngle); | ||
| kinematics.copyInto(wheelPositions, prevWheelPositions); | ||
| samples.clear(); | ||
| } | ||
|
|
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| private OptionalInt indexForTimestamp(double timestamp) { | ||
| if (samples.isEmpty()) { | ||
| return OptionalInt.empty(); | ||
| } | ||
|
|
||
| if (samples.getFirst().timestamp > timestamp) { | ||
| return OptionalInt.empty(); | ||
| } | ||
| if (samples.getLast().timestamp < timestamp) { | ||
| return OptionalInt.of(samples.size() - 1); | ||
| } | ||
| int low = 0; | ||
| int high = samples.size() - 1; | ||
| while (low <= high) { | ||
| int mid = (low + high) / 2; | ||
| double midTime = samples.get(mid).timestamp; | ||
| if (midTime < timestamp) { | ||
| low = mid + 1; | ||
| } else if (midTime > timestamp) { | ||
| high = mid - 1; | ||
| } else { | ||
| return OptionalInt.of(mid); | ||
| } | ||
| } | ||
| return OptionalInt.of(low - 1); | ||
| } | ||
|
|
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| private Pose2d poseAtIndex(int index) { | ||
| // switching this over to primitive math would be a good idea | ||
| Pose2d pose = rootPose; | ||
| for (int i = 0; i < index; i++) { | ||
| pose = pose.exp(samples.get(i)); | ||
| } | ||
| return pose; | ||
| } | ||
|
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| private void pruneToRoot() { | ||
| while (!samples.isEmpty() | ||
| && samples.getFirst().timestamp < RobotController.getTime() - kMaxSampleAge) { | ||
| rootPose = rootPose.exp(samples.removeFirst()); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Adds a sample to the estimator | ||
| * | ||
| * @param pose the pose of the robot at the time of the sample | ||
| * @param timestamp the timestamp of the sample | ||
| * @param weight the weight of the sample (0.0 to 1.0) | ||
| */ | ||
| public void addVisionMeasurement(Pose2d pose, double timestamp, Vector<N3> weight) { | ||
| var opt = indexForTimestamp(timestamp); | ||
| if (opt.isEmpty()) { | ||
| // timestamp is before the first sample | ||
| return; | ||
| } | ||
| int index = opt.getAsInt(); | ||
|
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||
| Pose2d lastPose = poseAtIndex(index); | ||
| Twist2d twist = lastPose.log(pose); | ||
| samples.add( | ||
| index, | ||
| new TimestampedTwist2d( | ||
| twist.dx * weight.get(0), | ||
| twist.dy * weight.get(1), | ||
| twist.dtheta * weight.get(2), | ||
| timestamp)); | ||
| pruneToRoot(); | ||
| } | ||
|
|
||
| public void updateWithTime( | ||
| SwerveModulePosition[] wheelPositions, | ||
| Rotation2d gyroAngle, | ||
| double timestamp, | ||
| Vector<N3> weight) { | ||
| var angle = gyroAngle.plus(gyroOffset); | ||
| var twist = kinematics.toTwist2d(prevWheelPositions, wheelPositions); | ||
| twist.dtheta = angle.minus(prevAngle).getRadians(); | ||
| Logger.recordOutput("PoseEstimator/PreviousWheelPositions", prevWheelPositions); | ||
| Logger.recordOutput("PoseEstimator/CurrentWheelPositions", wheelPositions); | ||
| Logger.recordOutput("PoseEstimator/Samples", samples.size()); | ||
| Logger.recordOutput("PoseEstimator/Twist", twist); | ||
|
|
||
| samples.add( | ||
| new TimestampedTwist2d( | ||
| twist.dx * weight.get(0), | ||
| twist.dy * weight.get(1), | ||
| twist.dtheta * weight.get(2), | ||
| timestamp)); | ||
|
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| kinematics.copyInto(wheelPositions, prevWheelPositions); | ||
| prevAngle = angle; | ||
| pruneToRoot(); | ||
| } | ||
|
|
||
| public Pose2d getEstimatedPose() { | ||
| return poseAtIndex(samples.size()); | ||
| } | ||
| } |
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