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/* ----------------------------------------------------------------------------
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
* Atlanta, Georgia 30332-0415
* All Rights Reserved
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
* See LICENSE for the license information
* -------------------------------------------------------------------------- */
/**
* @file EquivInertialNavFactor_GlobalVel_NoBias.h
* @author Vadim Indelman, Stephen Williams
* @brief Equivalent inertial navigation factor (velocity in the global frame), without bias state.
* @date May 9, 2013
**/
#pragma once
#include <gtsam/nonlinear/NonlinearFactor.h>
#include <gtsam/linear/NoiseModel.h>
#include <gtsam/geometry/Rot3.h>
#include <gtsam/base/Matrix.h>
// Using numerical derivative to calculate d(Pose3::Expmap)/dw
#include <gtsam/base/numericalDerivative.h>
#include <ostream>
namespace gtsam {
/*
* NOTES:
* =====
* Concept: Based on [Lupton12tro]
* - Pre-integrate IMU measurements using the static function PreIntegrateIMUObservations.
* Pre-integrated quantities are expressed in the body system of t0 - the first time instant (in which pre-integration began).
* All sensor-to-body transformations are performed here.
* - If required, calculate inertial solution by calling the static functions: predictPose_inertial, predictVelocity_inertial.
* - When the time is right, incorporate pre-integrated IMU data by creating an EquivInertialNavFactor_GlobalVel_NoBias factor, which will
* relate between navigation variables at the two time instances (t0 and current time).
*
* Other notes:
* - The global frame (NED or ENU) is defined by the user by specifying the gravity vector in this frame.
* - The IMU frame is implicitly defined by the user via the rotation matrix between global and imu frames.
* - Camera and IMU frames are identical
* - The user should specify a continuous equivalent noise covariance, which can be calculated using
* the static function CalcEquivalentNoiseCov based on the IMU gyro and acc measurement noise covariance
* matrices and the process\modeling covariance matrix. The IneritalNavFactor converts this into a
* discrete form using the supplied delta_t between sub-sequential measurements.
* - Earth-rate correction:
* + Currently the user should supply R_ECEF_to_G, which is the rotation from ECEF to the global
* frame (Local-Level system: ENU or NED, see above).
* + R_ECEF_to_G can be calculated by approximated values of latitude and longitude of the system.
* + Currently it is assumed that a relatively small distance is traveled w.r.t. to initial pose, since R_ECEF_to_G is constant.
* Otherwise, R_ECEF_to_G should be updated each time using the current lat-lon.
*
* - Frame Notation:
* Quantities are written as {Frame of Representation/Destination Frame}_{Quantity Type}_{Quatity Description/Origination Frame}
* So, the rotational velocity of the sensor written in the body frame is: body_omega_sensor
* And the transformation from the body frame to the world frame would be: world_P_body
* This allows visual chaining. For example, converting the sensed angular velocity of the IMU
* (angular velocity of the sensor in the sensor frame) into the world frame can be performed as:
* world_R_body * body_R_sensor * sensor_omega_sensor = world_omega_sensor
*
*
* - Common Quantity Types
* P : pose/3d transformation
* R : rotation
* omega : angular velocity
* t : translation
* v : velocity
* a : acceleration
*
* - Common Frames
* sensor : the coordinate system attached to the sensor origin
* body : the coordinate system attached to body/inertial frame.
* Unless an optional frame transformation is provided, the
* sensor frame and the body frame will be identical
* world : the global/world coordinate frame. This is assumed to be
* a tangent plane to the earth's surface somewhere near the
* vehicle
*/
template<class POSE, class VELOCITY>
class EquivInertialNavFactor_GlobalVel_NoBias : public NoiseModelFactorN<POSE, VELOCITY, POSE, VELOCITY> {
private:
typedef EquivInertialNavFactor_GlobalVel_NoBias<POSE, VELOCITY> This;
typedef NoiseModelFactorN<POSE, VELOCITY, POSE, VELOCITY> Base;
Vector delta_pos_in_t0_;
Vector delta_vel_in_t0_;
Vector3 delta_angles_;
double dt12_;
Vector world_g_;
Vector world_rho_;
Vector world_omega_earth_;
Matrix Jacobian_wrt_t0_Overall_;
std::optional<POSE> body_P_sensor_; // The pose of the sensor in the body frame
public:
// Provide access to the Matrix& version of evaluateError:
using Base::evaluateError;
// shorthand for a smart pointer to a factor
typedef typename std::shared_ptr<EquivInertialNavFactor_GlobalVel_NoBias> shared_ptr;
/** default constructor - only use for serialization */
EquivInertialNavFactor_GlobalVel_NoBias() {}
/** Constructor */
EquivInertialNavFactor_GlobalVel_NoBias(const Key& Pose1, const Key& Vel1, const Key& Pose2, const Key& Vel2,
const Vector& delta_pos_in_t0, const Vector& delta_vel_in_t0, const Vector3& delta_angles,
double dt12, const Vector world_g, const Vector world_rho,
const Vector& world_omega_earth, const noiseModel::Gaussian::shared_ptr& model_equivalent,
const Matrix& Jacobian_wrt_t0_Overall,
std::optional<POSE> body_P_sensor = {}) :
Base(model_equivalent, Pose1, Vel1, Pose2, Vel2),
delta_pos_in_t0_(delta_pos_in_t0), delta_vel_in_t0_(delta_vel_in_t0), delta_angles_(delta_angles),
dt12_(dt12), world_g_(world_g), world_rho_(world_rho), world_omega_earth_(world_omega_earth), Jacobian_wrt_t0_Overall_(Jacobian_wrt_t0_Overall),
body_P_sensor_(body_P_sensor) { }
virtual ~EquivInertialNavFactor_GlobalVel_NoBias() {}
/** implement functions needed for Testable */
/** print */
virtual void print(
const std::string& s = "EquivInertialNavFactor_GlobalVel_NoBias",
const KeyFormatter& keyFormatter = DefaultKeyFormatter) const {
std::cout << s << "("
<< keyFormatter(this->key<1>()) << ","
<< keyFormatter(this->key<2>()) << ","
<< keyFormatter(this->key<3>()) << ","
<< keyFormatter(this->key<4>()) << "\n";
std::cout << "delta_pos_in_t0: " << this->delta_pos_in_t0_.transpose() << std::endl;
std::cout << "delta_vel_in_t0: " << this->delta_vel_in_t0_.transpose() << std::endl;
std::cout << "delta_angles: " << this->delta_angles_ << std::endl;
std::cout << "dt12: " << this->dt12_ << std::endl;
std::cout << "gravity (in world frame): " << this->world_g_.transpose() << std::endl;
std::cout << "craft rate (in world frame): " << this->world_rho_.transpose() << std::endl;
std::cout << "earth's rotation (in world frame): " << this->world_omega_earth_.transpose() << std::endl;
if(this->body_P_sensor_)
this->body_P_sensor_->print(" sensor pose in body frame: ");
this->noiseModel_->print(" noise model");
}
/** equals */
bool equals(const NonlinearFactor& expected, double tol=1e-9) const override {
const This *e = dynamic_cast<const This*> (&expected);
return e != nullptr && Base::equals(*e, tol)
&& (delta_pos_in_t0_ - e->delta_pos_in_t0_).norm() < tol
&& (delta_vel_in_t0_ - e->delta_vel_in_t0_).norm() < tol
&& (delta_angles_ - e->delta_angles_).norm() < tol
&& (dt12_ - e->dt12_) < tol
&& (world_g_ - e->world_g_).norm() < tol
&& (world_rho_ - e->world_rho_).norm() < tol
&& (world_omega_earth_ - e->world_omega_earth_).norm() < tol
&& ((!body_P_sensor_ && !e->body_P_sensor_) || (body_P_sensor_ && e->body_P_sensor_ && body_P_sensor_->equals(*e->body_P_sensor_)));
}
POSE predictPose(const POSE& Pose1, const VELOCITY& Vel1) const {
/* Position term */
Vector delta_pos_in_t0_corrected = delta_pos_in_t0_;
/* Rotation term */
Vector delta_angles_corrected = delta_angles_;
return predictPose_inertial(Pose1, Vel1,
delta_pos_in_t0_corrected, delta_angles_corrected,
dt12_, world_g_, world_rho_, world_omega_earth_);
}
static inline POSE predictPose_inertial(const POSE& Pose1, const VELOCITY& Vel1,
const Vector& delta_pos_in_t0, const Vector3& delta_angles,
const double dt12, const Vector& world_g, const Vector& world_rho, const Vector& world_omega_earth){
const POSE& world_P1_body = Pose1;
const VELOCITY& world_V1_body = Vel1;
/* Position term */
Vector body_deltaPos_body = delta_pos_in_t0;
Vector world_deltaPos_pls_body = world_P1_body.rotation().matrix() * body_deltaPos_body;
Vector world_deltaPos_body = world_V1_body * dt12 + 0.5*world_g*dt12*dt12 + world_deltaPos_pls_body;
// Incorporate earth-related terms. Note - these are assumed to be constant between t1 and t2.
world_deltaPos_body -= 2*skewSymmetric(world_rho + world_omega_earth)*world_V1_body * dt12*dt12;
/* TODO: the term dt12*dt12 in 0.5*world_g*dt12*dt12 is not entirely correct:
* the gravity should be canceled from the accelerometer measurements, bust since position
* is added with a delta velocity from a previous term, the actual delta time is more complicated.
* Need to figure out this in the future - currently because of this issue we'll get some more error
* in Z axis.
*/
/* Rotation term */
Vector body_deltaAngles_body = delta_angles;
// Convert earth-related terms into the body frame
Matrix body_R_world(world_P1_body.rotation().inverse().matrix());
Vector body_rho = body_R_world * world_rho;
Vector body_omega_earth = body_R_world * world_omega_earth;
// Incorporate earth-related terms. Note - these are assumed to be constant between t1 and t2.
body_deltaAngles_body -= (body_rho + body_omega_earth)*dt12;
return POSE(Pose1.rotation() * POSE::Rotation::Expmap(body_deltaAngles_body), Pose1.translation() + typename POSE::Translation(world_deltaPos_body));
}
VELOCITY predictVelocity(const POSE& Pose1, const VELOCITY& Vel1) const {
Vector delta_vel_in_t0_corrected = delta_vel_in_t0_;
return predictVelocity_inertial(Pose1, Vel1,
delta_vel_in_t0_corrected,
dt12_, world_g_, world_rho_, world_omega_earth_);
}
static inline VELOCITY predictVelocity_inertial(const POSE& Pose1, const VELOCITY& Vel1,
const Vector& delta_vel_in_t0,
const double dt12, const Vector& world_g, const Vector& world_rho, const Vector& world_omega_earth) {
const POSE& world_P1_body = Pose1;
const VELOCITY& world_V1_body = Vel1;
Vector body_deltaVel_body = delta_vel_in_t0;
Vector world_deltaVel_body = world_P1_body.rotation().matrix() * body_deltaVel_body;
VELOCITY VelDelta( world_deltaVel_body + world_g * dt12 );
// Incorporate earth-related terms. Note - these are assumed to be constant between t1 and t2.
VelDelta -= 2*skewSymmetric(world_rho + world_omega_earth)*world_V1_body * dt12;
// Predict
return Vel1.compose( VelDelta );
}
void predict(const POSE& Pose1, const VELOCITY& Vel1, POSE& Pose2, VELOCITY& Vel2) const {
Pose2 = predictPose(Pose1, Vel1);
Vel2 = predictVelocity(Pose1, Vel1);
}
POSE evaluatePoseError(const POSE& Pose1, const VELOCITY& Vel1, const POSE& Pose2, const VELOCITY& Vel2) const {
// Predict
POSE Pose2Pred = predictPose(Pose1, Vel1);
// Calculate error
return Pose2.between(Pose2Pred);
}
VELOCITY evaluateVelocityError(const POSE& Pose1, const VELOCITY& Vel1, const POSE& Pose2, const VELOCITY& Vel2) const {
// Predict
VELOCITY Vel2Pred = predictVelocity(Pose1, Vel1);
// Calculate error
return Vel2.between(Vel2Pred);
}
Vector evaluateError(const POSE& Pose1, const VELOCITY& Vel1, const POSE& Pose2, const VELOCITY& Vel2,
OptionalMatrixType H1, OptionalMatrixType H2, OptionalMatrixType H3,
OptionalMatrixType H4) const {
// TODO: Write analytical derivative calculations
// Jacobian w.r.t. Pose1
if (H1){
Matrix H1_Pose = numericalDerivative11<POSE, POSE>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluatePoseError, this, _1, Vel1, Pose2, Vel2), Pose1);
Matrix H1_Vel = numericalDerivative11<VELOCITY, POSE>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluateVelocityError, this, _1, Vel1, Pose2, Vel2), Pose1);
*H1 = stack(2, &H1_Pose, &H1_Vel);
}
// Jacobian w.r.t. Vel1
if (H2){
Matrix H2_Pose = numericalDerivative11<POSE, VELOCITY>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluatePoseError, this, Pose1, _1, Pose2, Vel2), Vel1);
Matrix H2_Vel = numericalDerivative11<VELOCITY, VELOCITY>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluateVelocityError, this, Pose1, _1, Pose2, Vel2), Vel1);
*H2 = stack(2, &H2_Pose, &H2_Vel);
}
// Jacobian w.r.t. Pose2
if (H3){
Matrix H3_Pose = numericalDerivative11<POSE, POSE>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluatePoseError, this, Pose1, Vel1, _1, Vel2), Pose2);
Matrix H3_Vel = numericalDerivative11<VELOCITY, POSE>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluateVelocityError, this, Pose1, Vel1, _1, Vel2), Pose2);
*H3 = stack(2, &H3_Pose, &H3_Vel);
}
// Jacobian w.r.t. Vel2
if (H4){
Matrix H4_Pose = numericalDerivative11<POSE, VELOCITY>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluatePoseError, this, Pose1, Vel1, Pose2, _1), Vel2);
Matrix H4_Vel = numericalDerivative11<VELOCITY, VELOCITY>(std::bind(&EquivInertialNavFactor_GlobalVel_NoBias::evaluateVelocityError, this, Pose1, Vel1, Pose2, _1), Vel2);
*H4 = stack(2, &H4_Pose, &H4_Vel);
}
Vector ErrPoseVector(POSE::Logmap(evaluatePoseError(Pose1, Vel1, Pose2, Vel2)));
Vector ErrVelVector(VELOCITY::Logmap(evaluateVelocityError(Pose1, Vel1, Pose2, Vel2)));
return concatVectors(2, &ErrPoseVector, &ErrVelVector);
}
static inline POSE PredictPoseFromPreIntegration(const POSE& Pose1, const VELOCITY& Vel1,
const Vector& delta_pos_in_t0, const Vector3& delta_angles,
double dt12, const Vector world_g, const Vector world_rho,
const Vector& world_omega_earth, const Matrix& Jacobian_wrt_t0_Overall) {
/* Position term */
Vector delta_pos_in_t0_corrected = delta_pos_in_t0;
/* Rotation term */
Vector delta_angles_corrected = delta_angles;
// Another alternative:
// Vector delta_angles_corrected = Rot3::Logmap( Rot3::Expmap(delta_angles_)*Rot3::Expmap(J_angles_wrt_BiasGyro*delta_BiasGyro) );
return predictPose_inertial(Pose1, Vel1, delta_pos_in_t0_corrected, delta_angles_corrected, dt12, world_g, world_rho, world_omega_earth);
}
static inline VELOCITY PredictVelocityFromPreIntegration(const POSE& Pose1, const VELOCITY& Vel1,
const Vector& delta_vel_in_t0, double dt12, const Vector world_g, const Vector world_rho,
const Vector& world_omega_earth, const Matrix& Jacobian_wrt_t0_Overall) {
Vector delta_vel_in_t0_corrected = delta_vel_in_t0;
return predictVelocity_inertial(Pose1, Vel1, delta_vel_in_t0_corrected, dt12, world_g, world_rho, world_omega_earth);
}
static inline void PredictFromPreIntegration(const POSE& Pose1, const VELOCITY& Vel1, POSE& Pose2, VELOCITY& Vel2,
const Vector& delta_pos_in_t0, const Vector& delta_vel_in_t0, const Vector3& delta_angles,
double dt12, const Vector world_g, const Vector world_rho,
const Vector& world_omega_earth, const Matrix& Jacobian_wrt_t0_Overall) {
Pose2 = PredictPoseFromPreIntegration(Pose1, Vel1, delta_pos_in_t0, delta_angles, dt12, world_g, world_rho, world_omega_earth, Jacobian_wrt_t0_Overall);
Vel2 = PredictVelocityFromPreIntegration(Pose1, Vel1, delta_vel_in_t0, dt12, world_g, world_rho, world_omega_earth, Jacobian_wrt_t0_Overall);
}
static inline void PreIntegrateIMUObservations(const Vector& msr_acc_t, const Vector& msr_gyro_t, const double msr_dt,
Vector& delta_pos_in_t0, Vector3& delta_angles, Vector& delta_vel_in_t0, double& delta_t,
const noiseModel::Gaussian::shared_ptr& model_continuous_overall,
Matrix& EquivCov_Overall, Matrix& Jacobian_wrt_t0_Overall,
std::optional<POSE> p_body_P_sensor = {}){
// Note: all delta terms refer to an IMU\sensor system at t0
// Note: Earth-related terms are not accounted here but are incorporated in predict functions.
POSE body_P_sensor = POSE();
bool flag_use_body_P_sensor = false;
if (p_body_P_sensor){
body_P_sensor = *p_body_P_sensor;
flag_use_body_P_sensor = true;
}
delta_pos_in_t0 = PreIntegrateIMUObservations_delta_pos(msr_dt, delta_pos_in_t0, delta_vel_in_t0);
delta_vel_in_t0 = PreIntegrateIMUObservations_delta_vel(msr_gyro_t, msr_acc_t, msr_dt, delta_angles, delta_vel_in_t0, flag_use_body_P_sensor, body_P_sensor);
delta_angles = PreIntegrateIMUObservations_delta_angles(msr_gyro_t, msr_dt, delta_angles, flag_use_body_P_sensor, body_P_sensor);
delta_t += msr_dt;
// Update EquivCov_Overall
Matrix Z_3x3 = Z_3x3;
Matrix I_3x3 = I_3x3;
Matrix H_pos_pos = numericalDerivative11<Vector, Vector>(std::bind(&PreIntegrateIMUObservations_delta_pos, msr_dt, _1, delta_vel_in_t0), delta_pos_in_t0);
Matrix H_pos_vel = numericalDerivative11<Vector, Vector>(std::bind(&PreIntegrateIMUObservations_delta_pos, msr_dt, delta_pos_in_t0, _1), delta_vel_in_t0);
Matrix H_pos_angles = Z_3x3;
Matrix H_vel_vel = numericalDerivative11<Vector, Vector>(std::bind(&PreIntegrateIMUObservations_delta_vel, msr_gyro_t, msr_acc_t, msr_dt, delta_angles, _1, flag_use_body_P_sensor, body_P_sensor), delta_vel_in_t0);
Matrix H_vel_angles = numericalDerivative11<Vector, Vector>(std::bind(&PreIntegrateIMUObservations_delta_vel, msr_gyro_t, msr_acc_t, msr_dt, _1, delta_vel_in_t0, flag_use_body_P_sensor, body_P_sensor), delta_angles);
Matrix H_vel_pos = Z_3x3;
Matrix H_angles_angles = numericalDerivative11<Vector, Vector>(std::bind(&PreIntegrateIMUObservations_delta_angles, msr_gyro_t, msr_dt, _1, flag_use_body_P_sensor, body_P_sensor), delta_angles);
Matrix H_angles_pos = Z_3x3;
Matrix H_angles_vel = Z_3x3;
Matrix F_angles = collect(3, &H_angles_angles, &H_angles_pos, &H_angles_vel);
Matrix F_pos = collect(3, &H_pos_angles, &H_pos_pos, &H_pos_vel);
Matrix F_vel = collect(3, &H_vel_angles, &H_vel_pos, &H_vel_vel);
Matrix F = stack(3, &F_angles, &F_pos, &F_vel);
noiseModel::Gaussian::shared_ptr model_discrete_curr = calc_descrete_noise_model(model_continuous_overall, msr_dt );
Matrix Q_d = inverse(model_discrete_curr->R().transpose() * model_discrete_curr->R() );
EquivCov_Overall = F * EquivCov_Overall * F.transpose() + Q_d;
// Update Jacobian_wrt_t0_Overall
Jacobian_wrt_t0_Overall = F * Jacobian_wrt_t0_Overall;
}
static inline Vector PreIntegrateIMUObservations_delta_pos(const double msr_dt,
const Vector& delta_pos_in_t0, const Vector& delta_vel_in_t0){
// Note: all delta terms refer to an IMU\sensor system at t0
// Note: delta_vel_in_t0 is already in body frame, so no need to use the body_P_sensor transformation here.
return delta_pos_in_t0 + delta_vel_in_t0 * msr_dt;
}
static inline Vector PreIntegrateIMUObservations_delta_vel(const Vector& msr_gyro_t, const Vector& msr_acc_t, const double msr_dt,
const Vector3& delta_angles, const Vector& delta_vel_in_t0, const bool flag_use_body_P_sensor, const POSE& body_P_sensor){
// Note: all delta terms refer to an IMU\sensor system at t0
// Calculate the corrected measurements using the Bias object
Vector AccCorrected = msr_acc_t;
Vector body_t_a_body;
if (flag_use_body_P_sensor){
Matrix body_R_sensor = body_P_sensor.rotation().matrix();
Vector GyroCorrected(msr_gyro_t);
Vector body_omega_body = body_R_sensor * GyroCorrected;
Matrix body_omega_body__cross = skewSymmetric(body_omega_body);
body_t_a_body = body_R_sensor * AccCorrected - body_omega_body__cross * body_omega_body__cross * body_P_sensor.translation().vector();
} else{
body_t_a_body = AccCorrected;
}
Rot3 R_t_to_t0 = Rot3::Expmap(delta_angles);
return delta_vel_in_t0 + R_t_to_t0.matrix() * body_t_a_body * msr_dt;
}
static inline Vector PreIntegrateIMUObservations_delta_angles(const Vector& msr_gyro_t, const double msr_dt,
const Vector3& delta_angles, const bool flag_use_body_P_sensor, const POSE& body_P_sensor){
// Note: all delta terms refer to an IMU\sensor system at t0
// Calculate the corrected measurements using the Bias object
Vector GyroCorrected = msr_gyro_t;
Vector body_t_omega_body;
if (flag_use_body_P_sensor){
body_t_omega_body = body_P_sensor.rotation().matrix() * GyroCorrected;
} else {
body_t_omega_body = GyroCorrected;
}
Rot3 R_t_to_t0 = Rot3::Expmap(delta_angles);
R_t_to_t0 = R_t_to_t0 * Rot3::Expmap( body_t_omega_body*msr_dt );
return Rot3::Logmap(R_t_to_t0);
}
static inline noiseModel::Gaussian::shared_ptr CalcEquivalentNoiseCov(const noiseModel::Gaussian::shared_ptr& gaussian_acc, const noiseModel::Gaussian::shared_ptr& gaussian_gyro,
const noiseModel::Gaussian::shared_ptr& gaussian_process){
Matrix cov_acc = inverse( gaussian_acc->R().transpose() * gaussian_acc->R() );
Matrix cov_gyro = inverse( gaussian_gyro->R().transpose() * gaussian_gyro->R() );
Matrix cov_process = inverse( gaussian_process->R().transpose() * gaussian_process->R() );
cov_process.block(0,0, 3,3) += cov_gyro;
cov_process.block(6,6, 3,3) += cov_acc;
return noiseModel::Gaussian::Covariance(cov_process);
}
static inline void CalcEquivalentNoiseCov_DifferentParts(const noiseModel::Gaussian::shared_ptr& gaussian_acc, const noiseModel::Gaussian::shared_ptr& gaussian_gyro,
const noiseModel::Gaussian::shared_ptr& gaussian_process,
Matrix& cov_acc, Matrix& cov_gyro, Matrix& cov_process_without_acc_gyro){
cov_acc = inverse( gaussian_acc->R().transpose() * gaussian_acc->R() );
cov_gyro = inverse( gaussian_gyro->R().transpose() * gaussian_gyro->R() );
cov_process_without_acc_gyro = inverse( gaussian_process->R().transpose() * gaussian_process->R() );
}
static inline void Calc_g_rho_omega_earth_NED(const Vector& Pos_NED, const Vector& Vel_NED, const Vector& LatLonHeight_IC, const Vector& Pos_NED_Initial,
Vector& g_NED, Vector& rho_NED, Vector& omega_earth_NED) {
Matrix ENU_to_NED = (Matrix(3, 3) <<
0.0, 1.0, 0.0,
1.0, 0.0, 0.0,
0.0, 0.0, -1.0).finished();
Matrix NED_to_ENU = (Matrix(3, 3) <<
0.0, 1.0, 0.0,
1.0, 0.0, 0.0,
0.0, 0.0, -1.0).finished();
// Convert incoming parameters to ENU
Vector Pos_ENU = NED_to_ENU * Pos_NED;
Vector Vel_ENU = NED_to_ENU * Vel_NED;
Vector Pos_ENU_Initial = NED_to_ENU * Pos_NED_Initial;
// Call ENU version
Vector g_ENU;
Vector rho_ENU;
Vector omega_earth_ENU;
Calc_g_rho_omega_earth_ENU(Pos_ENU, Vel_ENU, LatLonHeight_IC, Pos_ENU_Initial, g_ENU, rho_ENU, omega_earth_ENU);
// Convert output to NED
g_NED = ENU_to_NED * g_ENU;
rho_NED = ENU_to_NED * rho_ENU;
omega_earth_NED = ENU_to_NED * omega_earth_ENU;
}
static inline void Calc_g_rho_omega_earth_ENU(const Vector& Pos_ENU, const Vector& Vel_ENU, const Vector& LatLonHeight_IC, const Vector& Pos_ENU_Initial,
Vector& g_ENU, Vector& rho_ENU, Vector& omega_earth_ENU){
double R0 = 6.378388e6;
double e = 1/297;
double Re( R0*( 1-e*(sin( LatLonHeight_IC(0) ))*(sin( LatLonHeight_IC(0) )) ) );
// Calculate current lat, lon
Vector delta_Pos_ENU(Pos_ENU - Pos_ENU_Initial);
double delta_lat(delta_Pos_ENU(1)/Re);
double delta_lon(delta_Pos_ENU(0)/(Re*cos(LatLonHeight_IC(0))));
double lat_new(LatLonHeight_IC(0) + delta_lat);
double lon_new(LatLonHeight_IC(1) + delta_lon);
// Rotation of lon about z axis
Rot3 C1(cos(lon_new), sin(lon_new), 0.0,
-sin(lon_new), cos(lon_new), 0.0,
0.0, 0.0, 1.0);
// Rotation of lat about y axis
Rot3 C2(cos(lat_new), 0.0, sin(lat_new),
0.0, 1.0, 0.0,
-sin(lat_new), 0.0, cos(lat_new));
Rot3 UEN_to_ENU(0, 1, 0,
0, 0, 1,
1, 0, 0);
Rot3 R_ECEF_to_ENU( UEN_to_ENU * C2 * C1 );
Vector omega_earth_ECEF((Vector(3) << 0.0, 0.0, 7.292115e-5));
omega_earth_ENU = R_ECEF_to_ENU.matrix() * omega_earth_ECEF;
// Calculating g
double height(LatLonHeight_IC(2));
double EQUA_RADIUS = 6378137.0; // equatorial radius of the earth; WGS-84
double ECCENTRICITY = 0.0818191908426; // eccentricity of the earth ellipsoid
double e2( pow(ECCENTRICITY,2) );
double den( 1-e2*pow(sin(lat_new),2) );
double Rm( (EQUA_RADIUS*(1-e2))/( pow(den,(3/2)) ) );
double Rp( EQUA_RADIUS/( sqrt(den) ) );
double Ro( sqrt(Rp*Rm) ); // mean earth radius of curvature
double g0( 9.780318*( 1 + 5.3024e-3 * pow(sin(lat_new),2) - 5.9e-6 * pow(sin(2*lat_new),2) ) );
double g_calc( g0/( pow(1 + height/Ro, 2) ) );
g_ENU = (Vector(3) << 0.0, 0.0, -g_calc);
// Calculate rho
double Ve( Vel_ENU(0) );
double Vn( Vel_ENU(1) );
double rho_E = -Vn/(Rm + height);
double rho_N = Ve/(Rp + height);
double rho_U = Ve*tan(lat_new)/(Rp + height);
rho_ENU = (Vector(3) << rho_E, rho_N, rho_U);
}
static inline noiseModel::Gaussian::shared_ptr calc_descrete_noise_model(const noiseModel::Gaussian::shared_ptr& model, double delta_t){
/* Q_d (approx)= Q * delta_t */
/* In practice, square root of the information matrix is represented, so that:
* R_d (approx)= R / sqrt(delta_t)
* */
return noiseModel::Gaussian::SqrtInformation(model->R()/sqrt(delta_t));
}
private:
#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
/** Serialization function */
friend class boost::serialization::access;
template<class ARCHIVE>
void serialize(ARCHIVE & ar, const unsigned int /*version*/) {
ar & boost::serialization::make_nvp("NonlinearFactor2",
boost::serialization::base_object<Base>(*this));
}
#endif
}; // \class EquivInertialNavFactor_GlobalVel_NoBias
} /// namespace gtsam
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