Module: thrMomentumDumping
Executive Summary
This module reads in the desired impulse that each thruster must produce to create inertial momentum change to despin the RWs.
The output of the module is a setup of thruster firing times. Each thruster can only fire for a maximum time that matches a single control period. After this the thrusters are off for an integer number of control periods to let the RW re-stabilize the attitude about an inertial pointing scenario. 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 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.
Figure 1: thrMomentumDumping() Module I/O Illustration
Msg Variable Name |
Msg Type |
Description |
|---|---|---|
thrusterOnTimeOutMsg |
thruster on time output message |
|
thrusterImpulseInMsg |
commanded thruster impulse input message |
|
thrusterConfInMsg |
Thruster array configuration input message |
|
deltaHInMsg |
requested momentum change input message |
Functions
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void SelfInit_thrMomentumDumping(thrMomentumDumpingConfig *configData, int64_t moduleID)
This method initializes the configData for this module. It creates a single output message of type THRArrayOnTimeCmdMsgPayload.
- Parameters:
configData – The configuration data associated with this module
moduleID – The ID associated with the configData
- Returns:
void
-
void Update_thrMomentumDumping(thrMomentumDumpingConfig *configData, uint64_t callTime, int64_t moduleID)
This method reads in the requested thruster impulse message. If it is a new message then a fresh thruster firing cycle is setup to achieve the desired RW momentum dumping. The the same message is read in, then the thrust continue to periodically fire to achieve the net thruster impuleses requested.
- 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_thrMomentumDumping(thrMomentumDumpingConfig *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
-
struct thrMomentumDumpingConfig
- #include <thrMomentumDumping.h>
thruster force momentum dumping module configuration message
Public Members
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int32_t thrDumpingCounter
counter to specify after how many contro period a thruster firing should occur.
-
double Delta_p[MAX_EFF_CNT]
vector of desired total thruster impulses
-
uint64_t lastDeltaHInMsgTime
time tag of the last momentum change input message
-
double thrOnTimeRemaining[MAX_EFF_CNT]
vector of remaining thruster on times
-
uint64_t priorTime
[ns] Last time the attitude control is called
-
int numThrusters
number of thrusters installed
-
double thrMaxForce[MAX_EFF_CNT]
[N] vector of maximum thruster forces
-
int maxCounterValue
this variable must be set to a non-zero value, indicating how many control periods to wait until the thrusters fire again to dump RW momentum
-
double thrMinFireTime
[s] smallest thruster firing time
-
THRArrayOnTimeCmdMsg_C thrusterOnTimeOutMsg
thruster on time output message name
-
THRArrayCmdForceMsg_C thrusterImpulseInMsg
desired thruster impulse input message name
-
THRArrayConfigMsg_C thrusterConfInMsg
The name of the thruster configuration Input message.
-
CmdTorqueBodyMsg_C deltaHInMsg
The name of the requested momentum change input message.
-
BSKLogger *bskLogger
BSK Logging.
-
int32_t thrDumpingCounter