navAggregate

Executive Summary

The purpose of this simple aggregate module is to read in a series of navigation messages, and combine their values into a single output message. The module is able to blend both attitude and translation navigation messages.

The number of input messages is defined through either attMsgCount or transMsgCount. If either of these values is zero, then the corresponding output navigation message is populated with zero components.

To select which input message value to use, the module index value must be set for that particular parameter. All these variables end with Idx. Their default values are 0, indicating that by default the values of the first navigation message are used. By changing the Idx value the user selects which message content to use for that variable. This can be set individually for each navigation message variable. In all cases the Idx index must be less than input navigation message counter attMsgCount or transMsgCount respectively.

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
navAttOutMsg	NavAttMsgPayload	blended attitude navigation output message
navTransOutMsg	NavTransMsgPayload	blended translation navigation output message
navAttInMsg	NavAttMsgPayload	attitude navigation input message stored inside the AggregateAttInput structure
navTransInMsg	NavTransMsgPayload	translation navigation input message stored inside the AggregateTransInput structure

User Guide

The array of messages must be of size 10 or less. The message count should be set to the number of input messages. If this is 0, then no input messages are read in and a zero output navigation message is produced. In the message count is larger than 10, then the variable is restricted to 10.

The outline to set up the navAggregate module in Python is as follows:

1. Import the module:

   from Basilisk.fswAlgorithms import navAggregate
   

2. Create an instantiation:

   module = navAggregate.NavAggregate()
   

3. Create input navigation message containers:

   navAtt1 = navAggregate.AggregateAttInput()
   navAtt2 = navAggregate.AggregateAttInput()
   navTrans1 = navAggregate.AggregateTransInput()
   navTrans2 = navAggregate.AggregateTransInput()
   

4. Add the aggregated messages:

   module.attMsgs = [navAtt1, navAtt2]
   module.transMsgs = [navTrans1, navTrans2]
   

5. Set the number of messages:

   module.setAttMsgCount(2)
   module.setTransMsgCount(2)
   

6. Set the various navigation information indices:

   # Use sun information from 2nd attitude navigation message, and remaining information from 1st message
   module.setAttTimeIdx(0)
   module.setAttIdx(0)
   module.setRateIdx(0)
   module.setSunIdx(1)
   # Use all translational information from 1st translational navigation message
   module.setTransTimeIdx(0)
   module.setPosIdx(0)
   module.setVelIdx(0)
   module.setDvIdx(0)
   

7. Subscribe to the messages:

   module.attMsgs[0].navAttInMsg.subscribeTo(navAtt1InMsg)
   module.attMsgs[1].navAttInMsg.subscribeTo(navAtt2InMsg)
   module.transMsgs[0].navTransInMsg.subscribeTo(navTrans1InMsg)
   module.transMsgs[1].navTransInMsg.subscribeTo(navTrans2InMsg)
   

8. Add model to task:

   sim.AddModelToTask(taskName, module)
   

Class NavAggregate

class NavAggregate : public SysModel

Public Functions

void reset(uint64_t callTime) override

This resets the module to original states.

Parameters:

callTime – The clock time at which the function was called (nanoseconds)

Returns:

void

void updateState(uint64_t callTime) override

This method takes the navigation message snippets created by the various navigation components in the FSW and aggregates them into a single complete navigation message.

Parameters:

callTime – The clock time at which the function was called (nanoseconds)

Returns:

void

void setAttTimeIdx(uint32_t idx)

Set the attitude time index.

Parameters:

idx – The new attitude time index to set.

uint32_t getAttTimeIdx() const

Get the attitude time index.

Returns:

uint32_t The current attitude time index.

void setTransTimeIdx(uint32_t idx)

Set the translation time index.

Parameters:

idx – The new translation time index to set.

uint32_t getTransTimeIdx() const

Get the translation time index.

Returns:

uint32_t The current translation time index.

void setAttIdx(uint32_t idx)

Set the attitude index.

Parameters:

idx – The new attitude index to set.

uint32_t getAttIdx() const

Get the attitude index.

Returns:

uint32_t The current attitude index.

void setRateIdx(uint32_t idx)

Set the rate index.

Parameters:

idx – The new rate index to set.

uint32_t getRateIdx() const

Get the rate index.

Returns:

uint32_t The current rate index.

void setPosIdx(uint32_t idx)

Set the position index.

Parameters:

idx – The new position index to set.

uint32_t getPosIdx() const

Get the position index.

Returns:

uint32_t The current position index.

void setVelIdx(uint32_t idx)

Set the velocity index.

Parameters:

idx – The new velocity index to set.

uint32_t getVelIdx() const

Get the velocity index.

Returns:

uint32_t The current velocity index.

void setDvIdx(uint32_t idx)

Set the accumulated DV index.

Parameters:

idx – The new accumulated DV index to set.

uint32_t getDvIdx() const

Get the accumulated DV index.

Returns:

uint32_t The current accumulated DV index.

void setSunIdx(uint32_t idx)

Set the sun index.

Parameters:

idx – The new sun index to set.

uint32_t getSunIdx() const

Get the sun index.

Returns:

uint32_t The current sun index.

void setAttMsgCount(uint32_t msgCount)

Set the attitude message count.

Parameters:

msgCount – The new attitude message count to set.

uint32_t getAttMsgCount() const

Get the attitude message count.

Returns:

uint32_t The current attitude message count.

void setTransMsgCount(uint32_t msgCount)

Set the translational message count.

Parameters:

msgCount – The new translational message count to set.

uint32_t getTransMsgCount() const

Get the translational message count.

Returns:

uint32_t The current translational message count.

Public Members

AggregateAttInput attMsgs[MAX_AGG_NAV_MSG]

[-] The incoming nav message buffer

AggregateTransInput transMsgs[MAX_AGG_NAV_MSG]

[-] The incoming nav message buffer

Message<NavAttMsgPayload> navAttOutMsg

blended attitude navigation output message

Message<NavTransMsgPayload> navTransOutMsg

blended translation navigation output message