Module: eulerRotation¶

Executive Summary¶

This module guidance modules creates constant Euler angle rate rotations about a primary axis to create dynamic reference frames.

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
attRefOutMsg	AttRefMsgPayload	name of the output message containing the Reference
attRefInMsg	AttRefMsgPayload	name of the guidance reference input message
desiredAttInMsg	AttStateMsgPayload	(optional) name of the incoming message containing the desired Euler angle set

User Guide¶

The initial orientation of the dynamic reference frame is set through the module variable angleSet. This is a 3-2-1 Euler angle sequence.

To set the desired constant 3-2-1 Euler angel rates, set the module variable angleRates.

Functions

void SelfInit_eulerRotation(eulerRotationConfig *configData, int64_t moduleID)¶

This method initializes the configData for eulerRotation model. It creates the module output message.

Parameters

configData – The configuration data associated with the null space control
moduleID – The ID associated with the configData

Returns

void

void Reset_eulerRotation(eulerRotationConfig *configData, uint64_t callTime, int64_t moduleID)¶

This resets the module to original states.

Parameters

configData – The configuration data associated with the null space control
callTime – The clock time at which the function was called (nanoseconds)
moduleID – The ID associated with the configData

Returns

void

void Update_eulerRotation(eulerRotationConfig *configData, uint64_t callTime, int64_t moduleID)¶

This method takes the input attitude reference frame, and and superimposes the dynamic euler angle scanning motion on top of this.

Parameters

configData – The configuration data associated with the mrpRotation module
callTime – The clock time at which the function was called (nanoseconds)
moduleID – The ID associated with the configData

Returns

void

void checkRasterCommands(eulerRotationConfig *configData)¶

This function checks if there is a new commanded raster maneuver message available.

Parameters: configData – The configuration data associated with the mrpRotation module
Returns: void

void computeTimeStep(eulerRotationConfig *configData, uint64_t callTime)¶

This function computes control update time.

Parameters

configData – The configuration data associated with the mrpRotation module
callTime – The clock time at which the function was called (nanoseconds)

Returns

void

void computeEuler321_Binv_derivative(double angleSet[3], double angleRates[3], double B_inv_deriv[3][3])¶

This function computes the analytical derivative of the B_inv matrix for the 3-2-1 Euler Angle set.

Parameters

angleSet – 321 Euler angles
angleRates – The 321 Euler angle rates
B_inv_deriv – the inv(B) matrix for 321 Euler angles

Returns

void

void computeEulerRotationReference(eulerRotationConfig *configData, double sigma_R0N[3], double omega_R0N_N[3], double domega_R0N_N[3], AttRefMsgPayload *attRefOut)¶

This function computes the reference (Euler angle attitude set, angular velocity and angular acceleration) associated with a rotation defined in terms of an initial euler angle set and a constant euler angle rate.

Parameters

configData – The configuration data associated with the mrpRotation module
sigma_R0N – The input reference attitude using MRPs
omega_R0N_N – The input reference frame angular rate vector
domega_R0N_N – The input reference frame angular acceleration vector
attRefOut – The output message copy

Returns

void

struct eulerRotationConfig¶

#include <eulerRotation.h>

Top level structure for the sub-module routines.

Public Members

double angleSet[3]¶: [-] current euler angle 321 set R/R0 with respect to the input reference

double angleRates[3]¶: [rad/s] euler angle 321 rates

double cmdSet[3]¶: [] msg commanded initial Euler angle 321 set with respect to input reference

double cmdRates[3]¶: [rad/s] msg commanded constant 321 Euler angle rates

double priorCmdSet[3]¶: [] prior commanded 321 Euler angle set

double priorCmdRates[3]¶: [rad/s] prior commanded 321 Euler angle rates

uint64_t priorTime¶: [ns] last time the guidance module is called

double dt¶: [s] integration time-step

AttRefMsg_C attRefOutMsg¶: The name of the output message containing the Reference.

AttRefMsg_C attRefInMsg¶: The name of the guidance reference input message.

AttStateMsg_C desiredAttInMsg¶: The name of the incoming message containing the desired EA set.

BSKLogger *bskLogger¶: BSK Logging.