C++ Module: dualHingedRigidBodyStateEffector

Executive Summary

Class to represent a solar array of two panels. The first panel is hinged on a single axis to the spacecraft body. The second panel is hinged to the first panel by a parallel axis on the opposite end of the first panel from the spacecraft body.)

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.

dualHingedRigidBodyStateEffector module input and output messages

Module I/O Messages

Msg Variable Name

Msg Type

Description

motorTorqueInMsg

ArrayMotorTorqueMsgPayload

(Optional) Input message of the two hinge motor torque values.

dualHingedRigidBodyOutMsgs

HingedRigidBodyMsgPayload

vector of output message containing the panel 1 and 2 hinge state angle and angle rate.

dualHingedRigidBodyConfigLogOutMsgs

SCStatesMsgPayload

vector of output messages containing the panel 1 and 2 inertial position and attitude states.

Initialization and Reset

mass1 and mass2 must each be finite and non-negative. Their sum must be finite and strictly positive because the model divides by the combined mass when computing the center of mass. Either panel may have zero mass if the configured inertias permit nonsingular hinge dynamics. dcm_H1B must be a finite, orthogonal, right-handed rotation matrix; scaled axes and reflections are rejected.

These checks run before state registration during spacecraft initialization, including when the effector is attached without being added to a task. Reset() performs the same checks without accessing parent states or changing integrated hinge states or motor commands. Invalid configurations raise BasiliskError. See Initialization and Configuration Validation.

Detailed Module Description

The module PDF Module Description contains further information on this module’s function, as well as testing.

User Guide

This section is to outline the steps needed to setup a Hinged Rigid Body State Effector in python using Basilisk.

  1. Import the dualHingedRigidBodyStateEffector class:

    from Basilisk.simulation import dualHingedRigidBodyStateEffector

  2. Create an instantiation of a Dual Hinged Rigid body:

    panel1 = dualHingedRigidBodyStateEffector.DualHingedRigidBodyStateEffector()

  3. Define all physical parameters for a Dual Hinged Rigid Body. For example:

    IPntS1_S1 = [[100.0, 0.0, 0.0], [0.0, 50.0, 0.0], [0.0, 0.0, 50.0]]

    Do this for all of the parameters for a Dual Hinged Rigid Body seen in the public variables in the .h file.

  4. Define the initial conditions of the states:

    panel1.theta1Init = 5*numpy.pi/180.0
panel1.theta1DotInit = 0.0
panel1.theta2Init = 5*numpy.pi/180.0
panel1.theta2DotInit = 0.0

  5. (Optional) Define a unique name for each state:

    panel1.nameOfTheta1State = "dualHingedRigidBodyTheta1"
panel1.nameOfTheta1DotState = "dualHingedRigidBodyThetaDot1"
panel1.nameOfTheta2State = "dualHingedRigidBodyTheta2"
panel1.nameOfTheta2DotState = "dualHingedRigidBodyThetaDot2"

  6. Define an optional motor torque input message with panel1.motorTorqueInMsg

  7. The module creates two output messages with the panel angular states. The messages are stored in the vector dualHingedRigidBodyOutMsgs.

  8. The module creates two output messages with each panel inertial position and attitude states. The messages are stored in the vector dualHingedRigidBodyConfigLogOutMsgs.

  9. Add the panel to your spacecraft:

    scObject.addStateEffector(panel1)

  10. Add the module to the task list:

    unitTestSim.AddModelToTask(unitTaskName, panel1)

Hosting a Dynamic Effector

This effector supports the branching described in Advanced: Effector Module Branching, so a compatible dynamic effector can be carried by one of the panels rather than by the hub:

panel1.addDynamicEffector(childEffector, segment)

Here segment is the one-based panel number, counting outward from the hub, so 1 is the panel attached to the hub.

This effector then makes its inertial position, velocity, attitude, and angular velocity available in place of the hub’s, and the child reads whichever of the four its model needs. Any geometry given to the child is expressed in that panel’s frame rather than the hub body frame. Both this effector and the child are still added to the task in the usual way.

class DualHingedRigidBodyStateEffector : public StateEffector, public SysModel
#include <dualHingedRigidBodyStateEffector.h>

dual hinged rigid body state effector

Public Functions

DualHingedRigidBodyStateEffector()
~DualHingedRigidBodyStateEffector()
void addDynamicEffector(DynamicEffector *newDynamicEffector, int segment) override

Method for adding attached dynamic effector.

This method attaches a dynamicEffector to one of the two panels

Parameters:

  • newDynamicEffector – the dynamic effector to be attached

  • segment – the panel to attach to, either 1 or 2

void registerProperties(DynParamManager &states) override

Method for registering the panel inertial properties.

This method registers the panel inertial properties with the dynamic parameter manager and links them into dependent dynamic effectors

Parameters:

states – [inout] Dynamic parameter manager used to register states or properties.

void registerStates(DynParamManager &statesIn) override

class method

Register the effector dynamics states.

Parameters:

statesIn – [inout] Dynamic parameter manager used to register states or properties.

void linkInStates(DynParamManager &states) override

class method

Link the required dynamics states.

Parameters:

states – [in] Dynamic parameter manager containing the required states.

void updateEffectorMassProps(double integTime) override

class method

Update the effector mass properties.

Parameters:

integTime – [in] [s] Current integration time.

void updateContributions(double integTime, BackSubMatrices &backSubContr, Eigen::MRPd sigma_BN, Eigen::Vector3d omega_BN_B, Eigen::Vector3d g_N) override

Back-sub contributions.

Update the effector Backsubstitution contributions.

Parameters:

  • integTime – [in] [s] Current integration time.

  • backSubContr – [inout] Backsubstitution contributions.

  • sigma_BN – [in] Hub attitude relative to the inertial frame.

  • omega_BN_B – [in] [rad/s] Hub angular velocity expressed in body-frame components.

  • g_N – [in] [m/s^2] Gravitational acceleration expressed in inertial-frame components.

void updateEnergyMomContributions(double integTime, Eigen::Vector3d &rotAngMomPntCContr_B, double &rotEnergyContr, Eigen::Vector3d omega_BN_B) override

Energy and momentum calculations.

This method is for calculating the contributions of the DHRB state effector to the energy and momentum of the s/c

Parameters:

  • integTime – [in] [s] Current integration time.

  • rotAngMomPntCContr_B – [inout] [kg*m^2/s] Rotational angular momentum contribution.

  • rotEnergyContr – [inout] [J] Rotational energy contribution.

  • omega_BN_B – [in] [rad/s] Hub angular velocity expressed in body-frame components.

void computeDerivatives(double integTime, Eigen::Vector3d rDDot_BN_N, Eigen::Vector3d omegaDot_BN_B, Eigen::MRPd sigma_BN) override

Method for each stateEffector to calculate derivatives.

Compute the effector state derivatives.

Parameters:

  • integTime – [in] [s] Current integration time.

  • rDDot_BN_N – [in] [m/s^2] Hub translational acceleration expressed in inertial-frame components.

  • omegaDot_BN_B – [in] [rad/s^2] Hub angular acceleration expressed in body-frame components.

  • sigma_BN – [in] Hub attitude relative to the inertial frame.

void Reset(uint64_t CurrentSimNanos) override

Validate configuration without changing integrated states or commands.

Parameters:

CurrentSimNanos – [in] [ns] Current simulation time.

void UpdateState(uint64_t CurrentSimNanos) override

This method is used so that the simulation will ask DHRB to update messages.

Parameters:

CurrentSimNanos – The current simulation time in nanoseconds

void writeOutputStateMessages(uint64_t CurrentClock) override

This method takes the computed theta states and outputs them to the m messaging system.

Parameters:

CurrentClock – The current simulation time (used for time stamping)

Public Members

double mass1

[kg] mass of 1st hinged rigid body

double mass2

[kg] mass of 2nd hinged rigid body

double d1

[m] distance from hinge point H1 to hinged rigid body center of mass S1

double d2

[m] distance from hinge point H2 to hinged rigid body center of mass S2

double l1

[m] distance from hinge point H1 to hinged point H2

double k1

[N-m/rad] torsional spring constant of hinge

double k2

[N-m/rad] torsional spring constant of hinge

double c1

[N-m-s/rad] rotational damping coefficient of hinge

double c2

[N-m-s/rad] rotational damping coefficient of hinge

double theta1Init

[rad] Initial hinged rigid body angle for first panel

double theta1DotInit

[rad/s] Initial hinged rigid body angle rate for first panel

double theta2Init

[rad] Initial hinged rigid body angle for second panel

double theta2DotInit

[rad/s] Initial hinged rigid body angle rate for second panel

Eigen::Matrix3d IPntS1_S1

[kg-m^2] Inertia of hinged rigid body about point S in S frame components

Eigen::Matrix3d IPntS2_S2

[kg-m^2] Inertia of hinged rigid body about point S in S frame components

Eigen::Vector3d r_H1B_B

[m] vector pointing from body frame origin to Hinge location

Eigen::Matrix3d dcm_H1B

[-] DCM from body frame to hinge frame

double thetaH2S1

[-] theta offset of H2 frame with respect to S1 frame

std::string nameOfTheta1State

[-] Identifier for the theta state data container

std::string nameOfTheta1DotState

[-] Identifier for the thetaDot state data container

std::string nameOfTheta2State

[-] Identifier for the theta state data container

std::string nameOfTheta2DotState

[-] Identifier for the thetaDot state data container

std::string nameOfInertialPositionProperty1

identifier for the panel 1 inertial position property

std::string nameOfInertialVelocityProperty1

identifier for the panel 1 inertial velocity property

std::string nameOfInertialAttitudeProperty1

identifier for the panel 1 inertial attitude property

std::string nameOfInertialAngVelocityProperty1

identifier for the panel 1 inertial angular velocity property

std::string nameOfInertialPositionProperty2

identifier for the panel 2 inertial position property

std::string nameOfInertialVelocityProperty2

identifier for the panel 2 inertial velocity property

std::string nameOfInertialAttitudeProperty2

identifier for the panel 2 inertial attitude property

std::string nameOfInertialAngVelocityProperty2

identifier for the panel 2 inertial angular velocity property

BSKLogger bskLogger

BSK Logging.

ReadFunctor<ArrayMotorTorqueMsgPayload> motorTorqueInMsg

(optional) motor torque input message

std::vector<Message<HingedRigidBodyMsgPayload>*> dualHingedRigidBodyOutMsgs

state output message vector for all panels

std::vector<Message<SCStatesMsgPayload>*> dualHingedRigidBodyConfigLogOutMsgs

panel state config log message vector for all panels

std::vector<DynamicEffector*> dynEffectors

Vector of dynamic effectors attached.

std::vector<int> dynEffectorSegments

Segment index for each attached dynamic effector.

Private Functions

void computePanelInertialStates()

This method computes the panel states relative to the inertial frame

void prependSpacecraftNameToStates() override

class method used for multiple spacecraft

template<typename Type>
inline void assignStateParamNames(Type effector, int segment)

Assign the state engine parameter names

void validateConfiguration()

Validate panel masses and the configured hinge-frame DCM.

Validate panel masses and the fixed hinge orientation before state registration.

Private Members

Eigen::Vector3d r_H1P_P

[m] vector pointing from primary body frame P origin to Hinge 1 location. If a single spacecraft body is modeled than P is the same as B

Eigen::Vector3d r_H2P_P

[m] vector pointing from primary body frame P origin to Hinge 2 location

Eigen::Matrix3d dcm_H1P

DCM from primary body frame to hinge 1 frame.

double u1

[N-m] motor torques on panel 1

double u2

[N-m] motor torques on panel 2

Eigen::Matrix3d rTildeH1B_B

[-] Tilde matrix of rHB_B

Eigen::Matrix3d dcm_S1P

[-] DCM from primary body to S1 frame

Eigen::Matrix3d dcm_S2P

[-] DCM from primary body to S2 frame

Eigen::Vector3d omega_PN_S1

[rad/s] omega_PN in S1 frame components

Eigen::Vector3d omega_PN_S2

[rad/s] omega_PN in S2 frame components

Eigen::Vector3d sHat11_P

[-] unit direction vector for the first axis of the S frame

Eigen::Vector3d sHat12_P

[-] unit direction vector for the second axis of the S frame

Eigen::Vector3d sHat13_P

[-] unit direction vector for the third axis of the S frame

Eigen::Vector3d sHat21_P

[-] unit direction vector for the first axis of the S frame

Eigen::Vector3d sHat22_P

[-] unit direction vector for the second axis of the S frame

Eigen::Vector3d sHat23_P

[-] unit direction vector for the third axis of the S frame

Eigen::Vector3d r_S1P_P

[-] Vector pointing from body origin to CoM of hinged rigid body in P frame comp

Eigen::Vector3d r_S2P_P

[-] Vector pointing from body origin to CoM of hinged rigid body in P frame comp

Eigen::Matrix3d rTildeS1P_P

[-] Tilde matrix of rSP_P

Eigen::Matrix3d rTildeS2P_P

[-] Tilde matrix of rSP_P

Eigen::Vector3d rPrimeS1P_P

[m/s] Body time derivative of rSP_P

Eigen::Vector3d rPrimeS2P_P

[m/s] Body time derivative of rSBP_P

Eigen::Matrix3d rPrimeTildeS1P_P

[-] Tilde matrix of rPrime_SP_P

Eigen::Matrix3d rPrimeTildeS2P_P

[-] Tilde matrix of rPrime_SP_P

Eigen::Matrix3d IS1PrimePntS1_P

[kg-m^2/s] time body derivative IPntS in primary body frame components

Eigen::Matrix3d IS2PrimePntS2_P

[kg-m^2/s] time body derivative IPntS in primary body frame components

Eigen::Vector3d omega_PNLoc_P

[rad/s] local copy of omegaPN

Eigen::Matrix3d omegaTildePNLoc_P

[-] tilde matrix of omegaPN

double theta1

[rad] hinged rigid body angle

double theta1Dot

[rad/s] hinged rigid body angle rate

double theta2

[rad] hinged rigid body angle

double theta2Dot

[rad/s] hinged rigid body angle rate

Eigen::Matrix2d matrixADHRB

[-] term needed for Backsubstitution

Eigen::Matrix2d matrixEDHRB

[-] term needed for Backsubstitution

Eigen::MatrixXd matrixFDHRB
Eigen::MatrixXd matrixGDHRB
Eigen::Vector2d vectorVDHRB
StateData *theta1State

[-] state manager of theta for hinged rigid body

StateData *theta1DotState

[-] state manager of thetaDot for hinged rigid body

StateData *theta2State

[-] state manager of theta for hinged rigid body

StateData *theta2DotState

[-] state manager of thetaDot for hinged rigid body

std::vector<Eigen::Vector3d> r_SN_N

[m] position vector of hinge CM S relative to inertial frame

std::vector<Eigen::Vector3d> v_SN_N

[m/s] inertial velocity vector of S relative to inertial frame

std::vector<Eigen::MatrixXd*> r_HN_N

[m] position vector of hinge point H relative to inertial frame

std::vector<Eigen::MatrixXd*> v_HN_N

[m/s] inertial velocity vector of H relative to inertial frame

std::vector<Eigen::MatrixXd*> sigma_SN

MRP attitude of panel frame S relative to inertial frame.

std::vector<Eigen::MatrixXd*> omega_SN_S

[rad/s] inertial panel frame angular velocity vector

Eigen::MRPd sigma_BN = {0.0, 0.0, 0.0}

Hub/Inertial attitude represented by MRP of body relative to inertial frame.

Eigen::Vector3d omega_BN_B = {0.0, 0.0, 0.0}

Hub/Inertial angular velocity vector in B frame components.

StateData *v_BN_NState

Hub/Inertial velocity vector in inertial frame components.

StateData *hubSigmaState = nullptr

hub attitude state, read live for the published kinematics

Eigen::MatrixXd *inertialPositionProperty

[m] r_N inertial position relative to system spice zeroBase/refBase

Eigen::MatrixXd *inertialVelocityProperty

[m] v_N inertial velocity relative to system spice zeroBase/refBase

Eigen::MatrixXd *g_N

[m/s^2] Gravitational acceleration in N frame components

Private Static Attributes

static uint64_t effectorID = 1

[] ID number of this panel