facetDragDynamicEffector

Executive Summary

Drag dynamics class used to compute drag effects on spacecraft bodies

This class is used to implement drag dynamic effects on spacecraft using a variety of simple or complex models, which will include cannonball (attitude-independent) drag, single flat-plate drag, faceted drag models, and an interface to full-CAD GPU-accellerated drag models. For more information see the PDF Description.

Message Connection Descriptions

The following table lists all the module input and output messages. The module msg variable name 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
atmoDensInMsg	AtmoPropsMsgPayload	input message for atmospheric density information

Class FacetDragDynamicEffector

class FacetDragDynamicEffector : public SysModel, public DynamicEffector

faceted atmospheric drag dynamic effector

Public Functions

void linkInStates(DynParamManager &states) override

This method is used to link the dragEffector to the hub attitude and velocity, which are required for calculating drag forces and torques.

Parameters:

states – dynamic parameter states

Returns:

void

void computeForceTorque(double integTime, double timeStep) override

This method computes the body forces and torques for the dragEffector in a simulation loop, selecting the model type based on the settable attribute “modelType.”

void updateState(uint64_t currentSimNanos) override

This method is called to update the local atmospheric conditions at each timestep. Naturally, this means that conditions are held piecewise-constant over an integration step.

Parameters:

currentSimNanos – The current simulation time in nanoseconds

Returns:

void

void addFacet(double area, double dragCoeff, Eigen::Vector3d B_normal_hat, Eigen::Vector3d B_location)

add a facet

Parameters:

• area –

• dragCoeff –

• B_normal_hat –

• B_location –

Public Members

uint64_t numFacets = 0

number of facets

ReadFunctor<AtmoPropsMsgPayload> atmoDensInMsg

atmospheric density input message

StateData *hubSigma

&#8212; Hub/Inertial attitude represented by MRP

StateData *hubVelocity

m/s Hub inertial velocity vector

Eigen::Vector3d v_B

m/s local variable to hold the inertial velocity

Eigen::Vector3d v_hat_B

class variable