Module: attRefCorrection
Executive Summary
This module reads in the attitude reference message and adjusts it by a fixed rotation. This allows a general body-fixed frame \(B\) to align with this corrected reference frame \(R_c\).
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.
Msg Variable Name |
Msg Type |
Description |
|---|---|---|
attRefInMsg |
attitude reference input message |
|
attRefOutMsg |
corrected attitude reference input message |
Detailed Module Description
This module is an attitude reference message feed-through module where a fixed orientation offset can be applied
to the output attitude sigma_RN. In not all cases do we wish to drive a body-fixed
frame \(\cal B\) to a reference frame \(\cal R\). Rather, maybe it is desired to align
the first \(\cal R\) frame axis with the 2nd body axis. Thus, a corrected body frame \({\cal B}_c\)
must align with R. The can also be achieved by aligning \(\cal B\) with a corrected attitude
reference frame \({\cal R}_c\).
Let the rotation between \(\cal B\) and \({\cal B}_c\) be given by the MRP set \(\sigma_{B/B_c}\). Using DCMs, thus we need
The original reference frame relates to the body frame through
which leads to
Substituting this into the first equatino leads to the desired corrected reference frame:
The orientation of \([R_cN]\) is then translated to a MRP set for the output message.
User Guide
The only variable that is set with this module is the sigma_BcB MRP to rotate from the original
body frame and the corrected frame.
Functions
-
void SelfInit_attRefCorrection(attRefCorrectionConfig *configData, int64_t moduleID)
This method initializes the output messages for this module.
- Parameters:
configData – The configuration data associated with this module
moduleID – The module identifier
- Returns:
void
-
void Update_attRefCorrection(attRefCorrectionConfig *configData, uint64_t callTime, int64_t moduleID)
Corrects the reference attitude message by a fixed rotation
- Parameters:
configData – The configuration data associated with the module
callTime – The clock time at which the function was called (nanoseconds)
moduleID – The module identifier
- Returns:
void
-
void Reset_attRefCorrection(attRefCorrectionConfig *configData, uint64_t callTime, int64_t moduleID)
This method performs a complete reset of the module. Local module variables that retain time varying states between function calls are reset to their default values. Check if required input messages are connected.
- Parameters:
configData – The configuration data associated with the module
callTime – [ns] time the method is called
moduleID – The module identifier
- Returns:
void
-
struct attRefCorrectionConfig
- #include <attRefCorrection.h>
This module reads in the attitude reference message and adjusts it by a fixed rotation. This allows a general body-fixed frame B to align with this corrected reference frame Rc.