C++ Module: radiationPressure
Executive Summary
Radiation pressure dynamics class used to compute
The module
PDF Description
contains further information on this module’s function,
how to run it, as well as testing.
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.
Msg Variable Name |
Msg Type |
Description |
|---|---|---|
sunEphmInMsg |
sun state input message. |
|
sunEclipseInMsg |
(optional) sun eclipse input message. |
Initialization and Reset
When the spacecraft links this effector to the hub states, initialization verifies that sunEphmInMsg is
connected. This validation occurs even if only the spacecraft is added to a task.
When the faceted CPU lookup model is selected, lookupSHat_B, lookupForce_B, and lookupTorque_B must
contain the same nonzero number of entries. Populate all three tables before initialization or Reset().
The check also runs before each lookup evaluation, so incomplete table edits or a model change after initialization
raise BasiliskError before any table entry is accessed. The cannonball model does not use these tables and
does not require them to be populated.
Attachment-time validation does not replace task scheduling for this effector. Add it to a task so that
UpdateState() refreshes the cached Sun ephemeris and optional eclipse data used during force evaluation.
When the effector is scheduled, its Reset() repeats the configuration checks.
Reset() does not clear the cached ephemeris, illumination, force, or torque data.
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class RadiationPressure : public SysModel, public DynamicEffector
- #include <radiationPressure.h>
solar radiation pressure dynamic effector
Public Functions
-
RadiationPressure()
This is the constructor. It sets some default initializers that can be overridden by the user.
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~RadiationPressure()
The destructor. Nothing of note is performed here
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void Reset(uint64_t CurrentSimNanos)
Validate the module configuration when the scheduler resets the model.
- Parameters:
CurrentSimNanos – [ns] Time at which the reset occurs
-
void UpdateState(uint64_t CurrentSimNanos)
Update model state by reading in new message data
- Parameters:
CurrentSimNanos – current simulation time in nanoseconds
-
void linkInStates(DynParamManager &statesIn)
This method retrieves pointers to parameters/data stored in the dynamic parameter manager
- Parameters:
statesIn – [in] Dynamic parameter manager containing the required states.
-
void readInputMessages()
This method is used to read the incoming ephemeris and spacecraft state messages. The data is stored in the associated buffer structure.
-
void computeForceTorque(double integTime, double timeStep)
This method computes the dynamic effect due to solar radiation pressure. It is an inherited method from the DynamicEffector class and is designed to be called by the simulation dynamics engine.
- Parameters:
integTime – Current simulation integration time
timeStep – Current integration time step used
-
void setUseCannonballModel()
Sets the model to the cannonball model in computing the solar radiation force
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void setUseFacetedCPUModel()
Sets the model to the faceted table-lookup model, evaluated on the CPU, in computing the solar radiation force
-
void addForceLookupBEntry(Eigen::Vector3d vec)
Add force vector in the body frame to lookup table.
- Parameters:
vec – (N) Force vector for particular attitude in lookup table
Public Members
-
double area
m^2 Body surface area
-
double coefficientReflection
Factor grouping surface optical properties.
-
ReadFunctor<SpicePlanetStateMsgPayload> sunEphmInMsg
sun state input message
-
ReadFunctor<EclipseMsgPayload> sunEclipseInMsg
(optional) sun eclipse input message
-
BSKLogger bskLogger
BSK Logging.
Private Functions
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void validateConfiguration()
Validate the required Sun input and dimensions of the selected lookup model.
-
void validateLookupDimensions()
Validate the three lookup table lengths.
Validate lookup dimensions before selecting or indexing a table entry.
-
void computeCannonballModel(Eigen::Vector3d rSunB_N)
Computes the solar radiation force vector based on cross-sectional Area and mass of the spacecraft and the position vector of the spacecraft to the sun. The solar radiation pressure decreases quadratically with distance from sun (in AU)
Solar Radiation Equations obtained from Earth Space and Planets Journal Vol. 51, 1999 pp. 979-986
- Parameters:
rSunB_N – [in] [m] Spacecraft-to-Sun position vector expressed in inertial-frame components.
-
void computeLookupModel(Eigen::Vector3d rSunB_B)
Computes the solar radiation force vector using a lookup table given the current spacecraft attitude and the position vector of the spacecraft to the sun. It is assumed that the lookup table has been generated with a solar flux at 1AU. Force and torque values are scaled.
- Parameters:
rSunB_B – [in] [m] Spacecraft-to-Sun position vector expressed in body-frame components.
Private Members
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srpModel_t srpModel
specifies which SRP model to use
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SpicePlanetStateMsgPayload sunEphmInBuffer
Buffer for incoming ephemeris message data.
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bool stateRead
Indicates a successful read of incoming SC state message data.
-
EclipseMsgPayload sunVisibilityFactor
[-] scaling parameter from 0 (fully obscured) to 1 (fully visible)
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RadiationPressure()