Files
allwpilib/wpimath/src/main/native/cpp/estimator/MecanumDrivePoseEstimator.cpp
2022-04-26 18:43:59 -07:00

119 lines
4.2 KiB
C++

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
#include "frc/estimator/MecanumDrivePoseEstimator.h"
#include <wpi/timestamp.h>
#include "frc/StateSpaceUtil.h"
#include "frc/estimator/AngleStatistics.h"
using namespace frc;
frc::MecanumDrivePoseEstimator::MecanumDrivePoseEstimator(
const Rotation2d& gyroAngle, const Pose2d& initialPose,
MecanumDriveKinematics kinematics,
const wpi::array<double, 3>& stateStdDevs,
const wpi::array<double, 1>& localMeasurementStdDevs,
const wpi::array<double, 3>& visionMeasurementStdDevs,
units::second_t nominalDt)
: m_observer(
[](const Eigen::Vector<double, 3>& x,
const Eigen::Vector<double, 3>& u) { return u; },
[](const Eigen::Vector<double, 3>& x,
const Eigen::Vector<double, 3>& u) { return x.block<1, 1>(2, 0); },
stateStdDevs, localMeasurementStdDevs, frc::AngleMean<3, 3>(2),
frc::AngleMean<1, 3>(0), frc::AngleResidual<3>(2),
frc::AngleResidual<1>(0), frc::AngleAdd<3>(2), nominalDt),
m_kinematics(kinematics),
m_nominalDt(nominalDt) {
SetVisionMeasurementStdDevs(visionMeasurementStdDevs);
// Create vision correction mechanism.
m_visionCorrect = [&](const Eigen::Vector<double, 3>& u,
const Eigen::Vector<double, 3>& y) {
m_observer.Correct<3>(
u, y,
[](const Eigen::Vector<double, 3>& x, const Eigen::Vector<double, 3>&) {
return x;
},
m_visionContR, frc::AngleMean<3, 3>(2), frc::AngleResidual<3>(2),
frc::AngleResidual<3>(2), frc::AngleAdd<3>(2));
};
// Set initial state.
m_observer.SetXhat(PoseTo3dVector(initialPose));
// Calculate offsets.
m_gyroOffset = initialPose.Rotation() - gyroAngle;
m_previousAngle = initialPose.Rotation();
}
void frc::MecanumDrivePoseEstimator::SetVisionMeasurementStdDevs(
const wpi::array<double, 3>& visionMeasurmentStdDevs) {
// Create R (covariances) for vision measurements.
m_visionContR = frc::MakeCovMatrix(visionMeasurmentStdDevs);
}
void frc::MecanumDrivePoseEstimator::ResetPosition(
const Pose2d& pose, const Rotation2d& gyroAngle) {
// Reset state estimate and error covariance
m_observer.Reset();
m_poseBuffer.Clear();
m_observer.SetXhat(PoseTo3dVector(pose));
m_gyroOffset = pose.Rotation() - gyroAngle;
m_previousAngle = pose.Rotation();
}
Pose2d frc::MecanumDrivePoseEstimator::GetEstimatedPosition() const {
return Pose2d(m_observer.Xhat(0) * 1_m, m_observer.Xhat(1) * 1_m,
Rotation2d(units::radian_t{m_observer.Xhat(2)}));
}
void frc::MecanumDrivePoseEstimator::AddVisionMeasurement(
const Pose2d& visionRobotPose, units::second_t timestamp) {
if (auto sample = m_poseBuffer.Sample(timestamp)) {
m_visionCorrect(Eigen::Vector<double, 3>::Zero(),
PoseTo3dVector(GetEstimatedPosition().TransformBy(
visionRobotPose - sample.value())));
}
}
Pose2d frc::MecanumDrivePoseEstimator::Update(
const Rotation2d& gyroAngle, const MecanumDriveWheelSpeeds& wheelSpeeds) {
return UpdateWithTime(units::microsecond_t(wpi::Now()), gyroAngle,
wheelSpeeds);
}
Pose2d frc::MecanumDrivePoseEstimator::UpdateWithTime(
units::second_t currentTime, const Rotation2d& gyroAngle,
const MecanumDriveWheelSpeeds& wheelSpeeds) {
auto dt = m_prevTime >= 0_s ? currentTime - m_prevTime : m_nominalDt;
m_prevTime = currentTime;
auto angle = gyroAngle + m_gyroOffset;
auto omega = (angle - m_previousAngle).Radians() / dt;
auto chassisSpeeds = m_kinematics.ToChassisSpeeds(wheelSpeeds);
auto fieldRelativeVelocities =
Translation2d(chassisSpeeds.vx * 1_s, chassisSpeeds.vy * 1_s)
.RotateBy(angle);
Eigen::Vector<double, 3> u{fieldRelativeVelocities.X().value(),
fieldRelativeVelocities.Y().value(),
omega.value()};
Eigen::Vector<double, 1> localY{angle.Radians().value()};
m_previousAngle = angle;
m_poseBuffer.AddSample(currentTime, GetEstimatedPosition());
m_observer.Predict(u, dt);
m_observer.Correct(u, localY);
return GetEstimatedPosition();
}