Module: magneticFieldBase

Executive Summary

General magnetic field base class used to calculate the magnetic field above a planet using multiple models. The MagneticField class is used to calculate the magnetic field vector above a body using multiple models. This base class is used to hold relevant planetary magnetic field properties to compute answers for a given set of spacecraft locations relative to a specified planet. Specific magnetic field models are implemented as classes that inherit from this base class. Planetary parameters, including position and input message, are settable by the user. In a given simulation, each planet of interest should have only one magnetic field model associated with it linked to the spacecraft in orbit about that body.

Each magnetic field is attached to a specific planet, but provides support for multiple spacecraft through addSpacecraftToModel().

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
scStateInMsgs	SCStatesMsgPayload	vector of spacecraft state input messages
envOutMsgs	MagneticFieldMsgPayload	vector of magnetic density output messages
planetPosInMsg	SpicePlanetStateMsgPayload	(optional) planet state input message. If not provided the planet state is zero information.
epochInMsg	EpochMsgPayload	(optional) epoch date/time input message

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class MagneticFieldBase : public SysModel

#include <magneticFieldBase.h>

magnetic field base class

Public Functions

MagneticFieldBase()

This method initializes some basic parameters for the module.

Returns

void

~MagneticFieldBase()

Destructor.

Returns

void

void Reset(uint64_t CurrentSimNanos)

This method is used to reset the module.

Returns

void

void addSpacecraftToModel(Message<SCStatesMsgPayload> *tmpScMsg)

Adds the spacecraft message name to a vector of sc message names and automatically creates an output message name.

Parameters

tmpScMsg – A spacecraft state message name.

Returns

void

void UpdateState(uint64_t CurrentSimNanos)

Computes the current local magnetic field for each spacecraft and writes their respective messages.

Parameters

CurrentSimNanos – The current simulation time in nanoseconds

Returns

void

Public Members

std::vector<ReadFunctor<SCStatesMsgPayload>> scStateInMsgs

Vector of the spacecraft position/velocity input message.

std::vector<Message<MagneticFieldMsgPayload>*> envOutMsgs

Vector of message names to be written out by the environment.

ReadFunctor<SpicePlanetStateMsgPayload> planetPosInMsg

Message name for the planet’s SPICE position message.

ReadFunctor<EpochMsgPayload> epochInMsg

(optional) epoch date/time input message

double envMinReach

[m] Minimum planet-relative position needed for the environment to work, default is off (neg. value)

double envMaxReach

[m] Maximum distance at which the environment will be calculated, default is off (neg. value)

double planetRadius

[m] Radius of the planet

BSKLogger bskLogger

BSK Logging

Protected Functions

void writeMessages(uint64_t CurrentClock)

This method is used to write the output magnetic field messages whose names are established in AddSpacecraftToModel.

Parameters

CurrentClock – The current time used for time-stamping the message

Returns

void

bool readMessages()

This method is used to read the incoming command message and set the associated spacecraft positions for computing the atmosphere.

Returns

void

void updateLocalMagField(double currentTime)

This method is used to update the local magnetic field based on each spacecraft’s position.

Returns

void

void updateRelativePos(SpicePlanetStateMsgPayload *planetState, SCStatesMsgPayload *scState)

This method is used to determine the spacecraft position vector relative to the planet.

Parameters

• planetState – A space planetstate message struct.

• scState – A spacecraft states message struct.

Returns

void

virtual void evaluateMagneticFieldModel(MagneticFieldMsgPayload *msg, double currentTime) = 0

class method

virtual void customReset(uint64_t CurrentClock)

Custom Reset() method. This allows a child class to add additional functionality to the Reset() method

Returns

void

virtual void customWriteMessages(uint64_t CurrentClock)

Custom output message writing method. This allows a child class to add additional functionality.

Returns

void

virtual bool customReadMessages()

Custom output input reading method. This allows a child class to add additional functionality.

Returns

void

virtual void customSetEpochFromVariable()

Custom customSetEpochFromVariable() method. This allows a child class to specify how the module epoch information is set by a module variable.

Returns

void

Protected Attributes

Eigen::Vector3d r_BP_N

[m] sc position vector relative to planet in inertial N frame components

Eigen::Vector3d r_BP_P

[m] sc position vector relative to planet in planet-fixed frame components

double orbitRadius

[m] sc orbit radius about planet

std::vector<MagneticFieldMsgPayload> magFieldOutBuffer

Message buffer for magnetic field messages

std::vector<SCStatesMsgPayload> scStates

vector of the spacecraft state messages

SpicePlanetStateMsgPayload planetState

planet state message

struct tm epochDateTime

time/date structure containing the epoch information using a Gregorian calendar