Module: thrForceMapping
Executive Summary
This module is reads in a desired attitude control torque vector and maps it onto a set of thrusters.
The module works for both on-pulsing (nominal thruster state is off such as with RCS thrusters) and off-pulsing (nominal thruster state in such as with DV thrusters). More information can be found in the
PDF Description.
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.
Msg Variable Name |
Msg Type |
Description |
|---|---|---|
thrForceCmdOutMsg |
thruster force output message |
|
cmdTorqueInMsg |
commanded attitude control torque vector input message |
|
thrConfigInMsg |
Thruster array configuration input message |
|
vehConfigInMsg |
spacecraft configuration input message |
Functions
-
void SelfInit_thrForceMapping(thrForceMappingConfig *configData, int64_t moduleID)
self init method
- Parameters:
configData – The configuration data associated with this module
moduleID – The ID associated with the configData
- Returns:
void
-
void Update_thrForceMapping(thrForceMappingConfig *configData, uint64_t callTime, int64_t moduleID)
The module takes a body frame torque vector and projects it onto available RCS or DV thrusters.
- Parameters:
configData – The configuration data associated with the module
callTime – The clock time at which the function was called (nanoseconds)
moduleID – The ID associated with the configData
- Returns:
void
-
void Reset_thrForceMapping(thrForceMappingConfig *configData, uint64_t callTime, int64_t moduleID)
This method performs a complete reset of the module. Local module variables that retain time varying states between function calls are reset to their default values.
- Parameters:
configData – The configuration data associated with the module
callTime – The clock time at which the function was called (nanoseconds)
moduleID – The ID associated with the configData
- Returns:
void
-
void substractMin(double *F, uint32_t size)
Take a stack of force values find the smallest value, and subtract if from all force values. Here the smallest values will become zero, while other forces increase. This assumes that the thrusters are aligned such that if all thrusters are firing, then no torque or force is applied. This ensures only positive force values are computed.
-
void findMinimumNormForce(thrForceMappingConfig *configData, double D[3][MAX_EFF_CNT], double Lr_B[3], uint32_t numForces, double F[MAX_EFF_CNT])
Use a least square inverse to determine the smallest set of thruster forces that yield the desired torque vector. Note that this routine does not constrain yet the forces to be either positive or negative
-
double computeTorqueAngErr(double D[3][MAX_EFF_CNT], double BLr[3], uint32_t numForces, double epsilon, double F[MAX_EFF_CNT], double FMag[MAX_EFF_CNT])
Determine the angle between the desired torque vector and the actual torque vector.
-
struct thrForceMappingConfig
- #include <thrForceMapping.h>
Data structure for module to map a command torque onto thruster forces.
Public Members
-
double controlAxes_B[3 * 3]
[] array of the control unit axes
-
double rThruster_B[MAX_EFF_CNT][3]
[m] local copy of the thruster locations
-
double gtThruster_B[MAX_EFF_CNT][3]
[] local copy of the thruster force unit direction vectors
-
int32_t thrForceSign
[] Flag indicating if pos (+1) or negative (-1) thruster solutions are found
-
double angErrThresh
[r] Angular error at which thruster forces are scaled to not be super-saturated
-
double epsilon
variable specifying what is considered a small number
-
uint32_t use2ndLoop
[] flag indicating if the 2nd least squares fitting loop should be used (1) or not used (0 - default)
-
uint32_t numControlAxes
[] counter indicating how many orthogonal axes are controlled
-
uint32_t numThrusters
[] The number of thrusters available on vehicle
-
double outTorqAngErr
[r] Angular error of effector torque
-
double thrForcMag[MAX_EFF_CNT]
vector of thruster force magnitudes
-
THRArrayCmdForceMsg_C thrForceCmdOutMsg
The name of the output thruster force message.
-
CmdTorqueBodyMsg_C cmdTorqueInMsg
The name of the vehicle control (Lr) Input message.
-
THRArrayConfigMsg_C thrConfigInMsg
The name of the thruster cluster Input message.
-
VehicleConfigMsg_C vehConfigInMsg
The name of the Input message.
-
VehicleConfigMsgPayload sc
spacecraft configuration message
-
BSKLogger *bskLogger
BSK Logging.
-
double controlAxes_B[3 * 3]