dragDynamicEffector¶

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-accelerated drag models.

struct DragBaseData¶

#include <dragDynamicEffector.h>

Container for basic drag parameters - the spacecraft’s atmosphere-relative velocity, its projected area, and its drag coefficient.

Public Members

double projectedArea¶: m^2 Area of spacecraft projected in velocity direction

double dragCoeff¶: Nondimensional drag coefficient

Eigen::Vector3d comOffset¶: m distance from center of mass to center of projected area

class DragDynamicEffector : public SysModel, public DynamicEffector ¶

Public Functions

DragDynamicEffector()¶

~DragDynamicEffector()¶: The destructor.

void linkInStates(DynParamManager &states)¶

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

Return

void

Parameters

currentTime: The current simulation time converted to a double

void computeForceTorque(double integTime)¶: 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 SelfInit()¶

This method currently does very little.

Return: void

void CrossInit()¶

This method is used to connect the input density message to the drag effector. It sets the message ID based on what it finds for the input string.

Return: void

void UpdateState(uint64_t CurrentSimNanos)¶

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.

Return

void

Parameters

CurrentSimNanos: The current simulation time in nanoseconds

void WriteOutputMessages(uint64_t CurrentClock)¶

The DragEffector does not write output messages to the rest of the sim.

Return: void

bool ReadInputs()¶

This method is used to read the incoming density message and update the internal density/ atmospheric data.

Return: void

void cannonballDrag()¶: This method implements a simple “cannnonball” (attitude-independent) drag model.

void updateDragDir()¶: This method updates the internal drag direction based on the spacecraft velocity vector.

void setDensityMessage(std::string newDensMessage)¶

This method is used to set the input density message produced by some atmospheric model.

Return: void

Public Members

DragBaseData coreParams¶: Struct used to hold drag parameters

std::string atmoDensInMsgName¶: message used to read command inputs

std::string navAttInMsgName¶: message used to read spacecraft attitude

std::string modelType¶: String used to set the type of model used to compute drag

StateData *hubSigma¶: 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¶: Drag force direction in the inertial frame

Private Members

uint64_t densInMsgId¶: Message ID for incoming data

AtmoPropsSimMsg atmoInData¶