Extending the Vehicle-Log Model¶

The vehicle “log model” class (AnalyzerVehicle::Base) provides a common model for analyzers to query log information, independent of the original log format.

This class exposes a subset of information from the original logs. If a new analyzer needs information that is not present in the model (but which was present in the original logs) then the model must be extended.

This process has three parts:

1. Extend AnalyzerVehicle::Base with members and functions that are appropriate for capturing the desired information and series of information. If you can infer useful vehicle-specific information from a message add it to the vehicle specific classes in the AnalyzerVehicle namespace (e.g. Copter).

2. Add a message type handler for the desired message in the dataflash log. This will populate the vehicle model appropriately and add data sources that can later be referenced by analyzers for the output:

   • Declare a handler class for the desired message type in LA_MsgHandler.h.

     This should be derived from LA_MsgHandler and implement the pure virtual method LA_MsgHandler::xprocess() (where you process the message and update the vehicle).

     The handler should also add “data sources” to its (inherited) _analyze variable using Analyze::add_data_source(). Each source would have a name used to reference the source in analyzers, and another string indicating associated the message type and field. For example:

     _analyze->add_data_source("EKF_FLAGS", "EKF4.SS");
     

   • Create an instance of the handler and pass a message to it in Analyzing_DataFlash_Message_Handler::handle_format_message_received().

3. Add a message type handler for the same message in tlogs. This also populates the vehicle model appropriately and adds data sources that can later be referenced by analyzers for the output (though the structure of code is quite different):

   • Update MAVLink_Message_Handler and Analyzing_MAVLink_Message_Handler with virtual handle_decoded_message() methods (and implementations). As before set the data sources for the processed messages.