Module fusion 

GNSS/INS fusion primitives.

The module keeps the already-merged inertial mechanization surface available while adding the indirect error-state prediction and EKF correction core.

Modules

config

Configuration and stochastic error parameters for inertial propagation.

ekf

Generic EKF correction and closed-loop reset for the indirect INS state.

error_state

ECEF indirect error-state system model and covariance prediction.

frames

WGS84 normal gravity and ECEF plumb-bob gravity vectors.

imu

IMU samples, calibration, and pre-mechanization correction.

loose

Loosely coupled GNSS PVT updates for the INS error-state filter.

mechanization

ECEF strapdown inertial mechanization.

serial

Versioned serialization for fusion filter checkpoints.

sim

Synthetic IMU generation from truth states or truth increments.

smoother

RTS fixed-interval smoothing for fusion error-state histories.

state

Error-state layout, filter state, and covariance validation.

tight

Tightly coupled raw GNSS updates for the INS error-state filter.

timesync

Time alignment for loosely coupled GNSS/INS updates.

ukf

Scaled-sigma-point unscented correction for the fusion error state.

Structs

AttitudeQuaternion

Unit quaternion using scalar-first (w, x, y, z) storage.

CorrectedImuIncrement

Bias-corrected, scale-corrected IMU increment consumed by mechanization.

EkfCorrection

Generic linearized EKF measurement correction.

EkfCorrectionReport

Diagnostics from one EKF correction attempt.

EkfUpdateOptions

EKF correction options.

ErrorStateImuKinematics

Body-frame IMU kinematics used to linearize the error-state model.

ErrorStateLinearization

Linearized continuous and discrete error-state model for one predict step.

ErrorStateVector

Indirect filter error vector.

F64Bits

Exact JSON representation of an f64 bit pattern.

FusionRtsEpoch

A recorded fusion epoch for RTS smoothing.

FusionRtsHistory

Recorded history accepted by smooth_fusion_rts.

FusionRtsHistoryBuilder

Builder for recording a forward fusion pass for RTS smoothing.

FusionUpdate

Result of one fusion update.

GnssFixMeasurement

GNSS PVT measurement used by the loose-coupled INS update.

GnssFixStatusWeighting

Sigma multipliers selected by GnssFixStatus.

IggIiiMeasurementReweighting

IGG-III measurement variance inflation for loose GNSS updates.

ImuBias

Accelerometer and gyroscope biases.

ImuCalibration

IMU scale-factor and misalignment matrices.

ImuErrorModel

Bias and calibration model applied before strapdown mechanization.

ImuRateRandomWalk

Optional rate-random-walk densities for the generated IMU.

ImuSample

One IMU sample tagged by its end time in seconds since J2000.

ImuSimulationOptions

Options for synthetic IMU generation.

ImuSimulator

Stateful deterministic synthetic IMU generator.

ImuSpec

Datasheet-level IMU stochastic parameters.

InertialFilter

Closed-loop INS filter with loose GNSS PVT updates.

InertialFilterConfig

Configuration for an InertialFilter.

InertialFilterSnapshot

Snapshot of a closed-loop inertial filter at one epoch.

InnovationGate

Innovation screening options.

InnovationGateReport

Diagnostics from an innovation screen.

InsFilterState

Closed-loop indirect INS filter state.

LooseCouplingConfig

Configuration for loose-coupled GNSS updates.

MechanizationConfig

Configuration for ECEF strapdown mechanization.

NavState

Navigation state used by the ECEF strapdown mechanizer.

NonHolonomicConstraintConfig

Non-holonomic wheeled-vehicle velocity constraint settings.

SerializableFusionSnapshot

Stable serializable fusion snapshot without retained replay history.

SerializableFusionState

Stable serializable fusion checkpoint.

SerializableImuSample

Serializable IMU sample.

SerializableInsFilterState

Serializable INS filter state and covariance.

SerializableLooseMeasurement

Serializable loose GNSS fix measurement.

SerializableNavState

Serializable navigation state with exact floating-point bit storage.

SerializableRateEndpoint

Serializable body-rate interpolation endpoint for retained IMU samples.

SerializableSatelliteId

Serializable GNSS satellite identifier.

SerializableStationarityDetectorSample

Serializable stationary-detector sample retained by a filter snapshot.

SerializableStoredCheckpoint

Serializable retained filter checkpoint.

SerializableStoredImuSample

Serializable retained IMU sample with its replay interval metadata.

SerializableTightCarrierPhaseObservation

Serializable tight carrier-phase observation.

SerializableTightFilterState

Serializable tight receiver-clock augmentation.

SerializableTightGnssEpoch

Serializable tight raw GNSS epoch.

SerializableTightGnssObservation

Serializable tight raw GNSS observation.

SerializableTightRangeRateObservation

Serializable tight range-rate observation.

SerializableTimeSyncHistory

Serializable retained time-sync replay history.

SerializableTimeSyncHistoryConfig

Serializable retained-history capacity settings.

SimulatedImuSequence

Batch output from synthetic IMU generation.

SmoothedFusionEpoch

One epoch in a smoothed fusion trajectory.

SmoothedFusionTrajectory

Smoothed trajectory returned by smooth_fusion_rts.

StationarityDetectorSnapshotSample

One retained stationary-detector sample stored in filter snapshots.

StationaryDetectorConfig

Windowed accel and gyro magnitude detector for stationary updates.

StationaryUpdateConfig

Stationarity detector and pseudo-measurement sigmas for ZUPT/ZARU.

StrapdownMechanizer

Streaming ECEF strapdown mechanizer.

TightCarrierPhaseObservation

Carrier-phase range row with a caller-supplied float ambiguity.

TightClockState

Receiver-clock state reported by the tight filter.

TightCouplingConfig

Configuration for tightly coupled raw GNSS updates.

TightFilterSnapshot

Snapshot of the tight clock augmentation for replay and restore.

TightGnssEpoch

One receiver epoch of raw GNSS observations for a tight update.

TightGnssObservation

Raw GNSS observation for one satellite in a tight update.

TightRangeRateObservation

Doppler-derived range-rate measurement for one satellite.

TimeSyncHistoryConfig

Retained history limits for bounded-latency time synchronization.

TimeSyncHistoryStatus

Current retained-history occupancy for time synchronization.

TimeSyncUpdate

Result of a time-synchronized loose GNSS update.

UkfUpdateOptions

UKF measurement-correction options.

UnscentedTransformOptions

Scaled unscented-transform parameters.

VelocityMatchState

One position/velocity sample used by velocity matching.

VelocityMatchedTrajectory

Output from endpoint velocity matching across one outage.

VelocityMatchingConfig

Endpoint matching settings for a GNSS outage span.

YangPredictionAdaptiveFactor

Yang two-segment predicted-residual adaptive factor for loose GNSS updates.

Enums

ConingCorrection

Strapdown coning-correction setting.

ErrorStateLayout

Error-state covariance layout.

FusionError

Error returned by GNSS/INS fusion primitives.

FusionFilterKind

Fusion filter family selector.

FusionStateCodecError

Errors returned by the versioned fusion-state codec.

GnssFixStatus

Upstream GNSS solution class used by loose measurement weighting.

ImuGrade

Coarse IMU class used to select a built-in ImuSpec preset.

ImuSampleKind

IMU sample payload.

ImuSimulationOutput

Output representation for generated IMU samples.

InertialError

Error returned by inertial frame, IMU, and mechanization entry points.

SerializableErrorStateLayout

Serializable error-state layout tag.

SerializableGnssFixStatus

Serializable loose GNSS fix status.

SerializableImuSampleKind

Serializable IMU sample payload.

SerializableStoredGnssMeasurement

Serializable retained GNSS measurement.

Constants

DEFAULT_IMU_SIM_SEED

Default deterministic seed used by ImuSimulationOptions::default.

DEFAULT_TIME_SYNC_CHECKPOINT_CAPACITY

Default number of retained GNSS checkpoints for time-sync replay.

DEFAULT_TIME_SYNC_IMU_CAPACITY

Default number of retained IMU samples for time-sync replay.

ERROR_ACCEL_BIAS_INDEX

Start index of accelerometer bias error states.

ERROR_ACCEL_SCALE_INDEX

Start index of accelerometer scale-factor error states in the 21-state layout.

ERROR_ATTITUDE_INDEX

Start index of ECEF attitude error states.

ERROR_GYRO_BIAS_INDEX

Start index of gyroscope bias error states.

ERROR_GYRO_SCALE_INDEX

Start index of gyroscope scale-factor error states in the 21-state layout.

ERROR_MOUNTING_MISALIGNMENT_INDEX

Reserved start index for future mounting-misalignment error states.

ERROR_MOUNTING_MISALIGNMENT_STATE_COUNT

Reserved mounting-misalignment state count for a later layout.

ERROR_POSITION_INDEX

Start index of ECEF position error states.

ERROR_STATE_DIMENSION_15

Number of states in the position, velocity, attitude, and bias layout.

ERROR_STATE_DIMENSION_21

Number of states after adding accelerometer and gyroscope scale factors.

ERROR_VELOCITY_INDEX

Start index of ECEF velocity error states.

FUSION_STATE_CODEC_VERSION

Current binary and serde schema version for fusion checkpoints.

TIGHT_CLOCK_BIAS_OFFSET

Receiver-clock bias index in the tight augmented covariance.

TIGHT_CLOCK_DRIFT_OFFSET

Receiver-clock drift index in the tight augmented covariance.

TIGHT_CLOCK_STATE_COUNT

Number of receiver-clock states appended to the INS error state.

WGS84_NORMAL_GRAVITY_EQUATOR_MPS2

WGS84 normal gravity at the equator in m/s^2.

WGS84_NORMAL_GRAVITY_POLE_MPS2

WGS84 normal gravity at the pole in m/s^2.

WGS84_SOMIGLIANA_K

Somigliana normal-gravity formula constant derived from WGS84 table values.

Functions

apply_closed_loop_error

Apply an indirect error estimate to the nominal INS state.

attitude_yaw_pitch_roll_rad

Convert a body-to-ECEF DCM to yaw, pitch, roll radians using a ZYX sequence.

covariance_is_positive_semidefinite

Test whether a covariance is positive semidefinite under numerical bounds.

dcm_to_quaternion

Convert a body-to-ECEF DCM to a unit quaternion.

ekf_correct_closed_loop

Apply one EKF correction, then close the loop and reset the error vector.

error_state_process_noise_discrete

Build the discrete process-noise covariance from an ImuSpec.

error_state_system_matrix_ecef

Build the ECEF error-state system matrix.

error_state_system_matrix_ecef_with_imu_to_body

Build the ECEF error-state system matrix with IMU axes rotated into body axes.

error_state_transition_matrix

Discretize F as I + F dt + 0.5 (F dt)^2.

gauss_markov_bias_decay

First-order Gauss-Markov bias decay factor over dt_s.

gauss_markov_bias_variance_increment

Bias process variance increment for a Gauss-Markov bias over dt_s.

gravity_ecef_mps2

WGS84 normal gravity vector in ECEF coordinates, in m/s^2.

joseph_covariance_update

Compute Joseph-form covariance update.

linearize_error_state_ecef

Build F, Phi, and Q_d for one error-state predict step.

linearize_error_state_ecef_with_imu_to_body

Build F, Phi, and Q_d for one predict step with IMU axes rotated into body axes.

loose_coupling_correction

Build the loose-coupled GNSS EKF correction for an INS state.

mechanize_ecef

Propagate an ECEF navigation state by one corrected IMU increment.

normal_gravity_mps2

WGS84 Somigliana normal gravity magnitude at geodetic latitude and height.

predict_error_state_covariance

Predict covariance as P = Phi P Phi^T + Q_d.

quaternion_to_dcm

Convert a unit quaternion to a body-to-ECEF DCM.

reorthonormalize_dcm

Re-orthonormalize a direction-cosine matrix into a right-handed frame.

reproject_covariance_psd

Symmetrize and reproject a covariance onto the PSD cone under numerical bounds.

rodrigues_delta_dcm

Exact Rodrigues direction-cosine matrix for a body delta angle.

simulate_imu_samples

Generate IMU samples from a navigation-state truth trajectory.

simulate_imu_samples_from_increments

Generate IMU samples from coning/sculling truth increments.

smooth_fusion_rts

Apply the RTS fixed-interval smoother to a recorded fusion history.

true_imu_increment_between

Reconstruct the mechanization-consistent truth increment between two states.

ukf_correct_closed_loop

Apply a linear UKF correction, then close the loop and reset the error vector.

validate_covariance_matrix

Validate covariance shape, finiteness, symmetry, and PSD.

validate_time_sync_gnss_order

Validate strictly increasing GNSS measurement epochs.

validate_time_sync_imu_order

Validate strictly increasing IMU sample epochs.

velocity_match_outage

Blend a first good post-outage fix back over an outage span.

velocity_match_outage_to_state

Blend an outage span to a caller-supplied endpoint state.