sunlineSEKF#

Executive Summary#

This module implements and tests a Switch Extended Kalman Filter in order to estimate the sunline direction.

More information can be found in the PDF Description

Message Connection Descriptions#

The following table lists all the module input and output messages. The module msg connection is set by the user from python. The msg type contains a link to the message structure definition, while the description provides information on what this message is used for.

Module I/O Messages#
Msg Variable Name	Msg Type	Description
navStateOutMsg	NavAttMsgPayload	name of the navigation output message containing the estimated states
filtDataOutMsg	SunlineFilterMsgPayload	name of the output filter data message
cssDataInMsg	CSSArraySensorMsgPayload	name of the CSS sensor input message
cssConfigInMsg	CSSConfigMsgPayload	name of the CSS configuration input message

Class SunlineSEKF#

class SunlineSEKF : public SysModel#

Top level structure for the CSS-based Switch Extended Kalman Filter. Used to estimate the sun state in the vehicle body frame.

Public Functions

void reset(uint64_t callTime) override#

This method resets the sunline attitude filter to an initial state and initializes the internal estimation matrices.

Parameters:: callTime – The clock time at which the function was called (nanoseconds)
Returns:: void

void updateState(uint64_t callTime) override#

This method takes the parsed CSS sensor data and outputs an estimate of the sun vector in the ADCS body frame

Parameters:: callTime – The clock time at which the function was called (nanoseconds)
Returns:: void

Public Members

Message<NavAttMsgPayload> navStateOutMsg#: The name of the output message

Message<SunlineFilterMsgPayload> filtDataOutMsg#: The name of the output filter data message

ReadFunctor<CSSArraySensorMsgPayload> cssDataInMsg#: The name of the Input message

ReadFunctor<CSSConfigMsgPayload> cssConfigInMsg#: [-] The name of the CSS configuration message

double qObsVal#: [-] CSS instrument noise parameter

double qProcVal#: [-] Process noise parameter

double dt#: [s] seconds since last data epoch

double timeTag#: [s] Time tag for statecovar/etc

double bVec_B[SKF_N_STATES_HALF]#: [-] current vector of the b frame used to make Switch frame

double switchTresh#: [-] Cosine of angle between singularity and S-frame. If close to 1, the threshold for switching frames is lower. If closer to 0.5 singularity is more largely avoided but switching is more frequent

double state[EKF_N_STATES_SWITCH]#: [-] State estimate for time TimeTag

double x[EKF_N_STATES_SWITCH]#: State errors

double xBar[EKF_N_STATES_SWITCH]#: [-] Current mean state estimate

double covarBar[EKF_N_STATES_SWITCH * EKF_N_STATES_SWITCH]#: [-] Time updated covariance

double covar[EKF_N_STATES_SWITCH * EKF_N_STATES_SWITCH]#: [-] covariance

double stateTransition[EKF_N_STATES_SWITCH * EKF_N_STATES_SWITCH]#: [-] State transition Matrix

double kalmanGain[EKF_N_STATES_SWITCH * MAX_N_CSS_MEAS]#: Kalman Gain

double dynMat[EKF_N_STATES_SWITCH * EKF_N_STATES_SWITCH]#: [-] Dynamics Matrix, A

double measMat[MAX_N_CSS_MEAS * EKF_N_STATES_SWITCH]#: [-] Measurement Matrix, H

double W_BS[EKF_N_STATES_SWITCH * EKF_N_STATES_SWITCH]#: [-] Switch Matrix to bring states and covariance to new S-frame when switch occurs

double obs[MAX_N_CSS_MEAS]#: [-] Observation vector for frame

double yMeas[MAX_N_CSS_MEAS]#: [-] Linearized measurement model data

double postFits[MAX_N_CSS_MEAS]#: [-] PostFit residuals

double procNoise[(EKF_N_STATES_SWITCH - 3) * (EKF_N_STATES_SWITCH - 3)]#: [-] process noise matrix

double measNoise[MAX_N_CSS_MEAS * MAX_N_CSS_MEAS]#: [-] Maximally sized obs noise matrix

double cssNHat_B[MAX_NUM_CSS_SENSORS * 3]#: [-] CSS normal vectors converted over to body

uint32_t numStates#: [-] Number of states for this filter

size_t numObs#: [-] Number of measurements this cycle

uint32_t numActiveCss#: — Number of currently active CSS sensors

uint32_t numCSSTotal#: [-] Count on the number of CSS we have on the spacecraft

double sensorUseThresh#: — Threshold below which we discount sensors

double eKFSwitch#: — Max covariance element after which the filter switches to an EKF

NavAttMsgPayload outputSunline#: — Output sunline estimate data

CSSArraySensorMsgPayload cssSensorInBuffer#: [-] CSS sensor data read in from message bus

BSKLogger bskLogger = {}#: BSK Logging.

sunlineSEKF#

Executive Summary#

Message Connection Descriptions#

Class SunlineSEKF#

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