inertial3D

Executive Summary

This attitude guidance module create a reference attitude message that points in fixed inertial direction.

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	attitude reference output message

Reference Frame Generation

The modules requires the desired reference orientation in terms of the MRP set \(\mathbf{\sigma}_{R_0 N}\). This input is only set once and does not have to be changed. Let us designate \(\mathcal{R}\) as the output generated reference frame. Since the fixed-pointing is inertial:

\[\begin{split}\mathbf{\sigma}_{RN} = \mathbf{\sigma}_{R_0 N} \\ \mathbf{\omega}_{RN} = \dot{\mathbf{\omega}}_{RN} = 0\end{split}\]

User Guide

The required module configuration is:

attGuid = inertial3D.inertial3D()
attGuid.setSigmaR0N(sigma_R0N)

Class Inertial3D

class Inertial3D : public SysModel

Data structure for module to compute the Inertial-3D pointing navigation solution.

Public Functions

void updateState(uint64_t callTime) override

This method creates a fixed attitude reference message. The desired orientation is defined within the module.

Parameters:

callTime – The clock time at which the function was called (nanoseconds)

Returns:

void

void setSigmaR0N(const Eigen::Vector3d &sigma_RN)

Setter method for the MRP from frame N to frame R.

Parameters:

sigma_RN – [-] MRP from frame N to frame R

Returns:

void

const Eigen::Vector3d &getSigmaR0N() const

Getter method for the MRP from frame N to frame R.

Returns:

const Eigen::Vector3d

Public Members

Message<AttRefMsgPayload> attRefOutMsg

reference attitude output message