class mola::NavStateFG

Overview

Sliding window Factor-graph data fusion for odometry, IMU, GNSS, and SE(3) pose/twist estimations.

Frame conventions:

There is a frame of reference for each source of odometry, e.g. there may be one for LiDAR-odometry, another for visual-odometry, or wheels-based odometry, etc. Each such frame is referenced with a “frame
name” (an arbitrary string).
Internally, the first frame of reference will be used as “global” coordinates, despite it may be actually either a map or odom frame, in the ROS REP 105 sense.
IMU readings are, by definition, given in the robot body frame, although they can have a relative transformation between the vehicle and sensor.

Main API methods and frame conventions:

estimated_navstate() : Output estimations can be requested in any of the existing frames of reference.
fuse_pose() : Can be used to integrate information from any “odometry” or “localization” input, as mentioned above.
fuse_gnss() : TO-DO.
fuse_imu() : TO-DO.

Usage:

1. Call initialize() or set the required parameters directly in params_.
1. Integrate measurements with fuse_*() methods. Each CObservation class includes a timestamp field which is used to estimate the trajectory.
1. Repeat (2) as needed.
1. Read the estimation up to any nearby moment in time with estimated_navstate()

Old observations are automatically removed.

A constant SE(3) velocity model is internally used, without any particular assumptions on the vehicle kinematics.

For more theoretical descriptions, see the papers cited in https://docs.mola-slam.org/latest/

#include <NavStateFG.h>

class NavStateFG: public mola::NavStateFilter
{
public:
    // structs

    struct GtsamImpl;
    struct OdomData;
    struct PointData;
    struct PoseData;
    struct QueryPointData;
    struct State;
    struct TwistData;

    // fields

    NavStateFGParams params_;

    // methods

    virtual void initialize(const mrpt::containers::yaml& cfg);
    virtual void reset();

    virtual void fuse_pose(
        const mrpt::Clock::time_point& timestamp,
        const mrpt::poses::CPose3DPDFGaussian& pose,
        const std::string& frame_id
        );

    virtual void fuse_odometry(
        const mrpt::obs::CObservationOdometry& odom,
        const std::string& odomName = "odom_wheels"
        );

    virtual void fuse_imu(const mrpt::obs::CObservationIMU& imu);
    virtual void fuse_gnss(const mrpt::obs::CObservationGPS& gps);

    virtual void fuse_twist(
        const mrpt::Clock::time_point& timestamp,
        const mrpt::math::TTwist3D& twist,
        const mrpt::math::CMatrixDouble66& twistCov
        );

    virtual std::optional<NavState> estimated_navstate(
        const mrpt::Clock::time_point& timestamp,
        const std::string& frame_id
        );

    auto known_frame_ids();

    void set_georeferencing_params(
        mrpt::topography::TGeodeticCoords geo_coord,
        mrpt::poses::CPose3DPDFGaussian T_enu_to_map
        );
};

Inherited Members

public:
    // structs

    struct GeoReferenceParams;

    // methods

    virtual void reset() = 0;
    virtual void initialize(const mrpt::containers::yaml& cfg) = 0;

    virtual void fuse_pose(
        const mrpt::Clock::time_point& timestamp,
        const mrpt::poses::CPose3DPDFGaussian& pose,
        const std::string& frame_id
        ) = 0;

    virtual void fuse_odometry(
        const mrpt::obs::CObservationOdometry& odom,
        const std::string& odomName = "odom_wheels"
        ) = 0;

    virtual void fuse_imu(const mrpt::obs::CObservationIMU& imu) = 0;
    virtual void fuse_gnss(const mrpt::obs::CObservationGPS& gps) = 0;

    virtual void fuse_twist(
        const mrpt::Clock::time_point& timestamp,
        const mrpt::math::TTwist3D& twist,
        const mrpt::math::CMatrixDouble66& twistCov
        ) = 0;

    virtual std::optional<NavState> estimated_navstate(
        const mrpt::Clock::time_point& timestamp,
        const std::string& frame_id
        ) = 0;

Methods

virtual void initialize(const mrpt::containers::yaml& cfg)

Initializes the object and reads all parameters from a YAML node.

Parameters:

cfg	a YAML node with a dictionary of parameters to load from.

virtual void reset()

Resets the estimator state to an initial state

virtual void fuse_pose(
    const mrpt::Clock::time_point& timestamp,
    const mrpt::poses::CPose3DPDFGaussian& pose,
    const std::string& frame_id
    )

Integrates new SE(3) pose estimation of the vehicle wrt frame_id

virtual void fuse_odometry(
    const mrpt::obs::CObservationOdometry& odom,
    const std::string& odomName = "odom_wheels"
    )

Integrates new wheels-based odometry observations into the estimator. This is a convenience method that internally ends up calling fuse_pose(), but computing the uncertainty of odometry increments according to a given motion model.

virtual void fuse_imu(const mrpt::obs::CObservationIMU& imu)

Integrates new IMU observations into the estimator

virtual void fuse_gnss(const mrpt::obs::CObservationGPS& gps)

Integrates new GNSS observations into the estimator

virtual void fuse_twist(
    const mrpt::Clock::time_point& timestamp,
    const mrpt::math::TTwist3D& twist,
    const mrpt::math::CMatrixDouble66& twistCov
    )

Integrates new twist estimation (in the odom frame)

virtual std::optional<NavState> estimated_navstate(
    const mrpt::Clock::time_point& timestamp,
    const std::string& frame_id
    )

Computes the estimated vehicle state at a given timestep using the observations in the time window. A std::nullopt is returned if there is no valid observations yet, or if requested a timestamp out of the model validity time window (e.g. too far in the future to be trustful).

auto known_frame_ids()

Returns a list of known frame_ids:

void set_georeferencing_params(
    mrpt::topography::TGeodeticCoords geo_coord,
    mrpt::poses::CPose3DPDFGaussian T_enu_to_map
    )

Must be invoked with the mp2p_icp metric map geo-referencing information of the map in order to have GNSS observations correctly fused.