Parameters

• The full PX4 parameter guide can be found here

The default value for all parameters is built into the software image. Any parameter values that are changed from their default values are stored in a parameter file in the file system. The default location for this file is /data/px4/param/parameters. In order to get back to the default setting for all parameters one can delete this file.

ModalAI Parameter Sets

ModalAI provides sets of parameters that can be used for the various reference drones and for various use cases. These parameter sets are stored in a format that allows them to be loaded onto the drone with QGroundControl using the load from file option. These parameter sets are available here

If PX4 is started via the /usr/bin/voxl-px4 script and the parameters file does not exist it will create one populated with the parameters listed in the file /etc/modalai/voxl-px4-set-default-parameters.config

Viewing/Editing Parameters

You can use the param subsystem to interact with the parameters, e.g. viewing:

px4-param show

Log files

PX4 log files can be a valuable way to tune performance of your drone or debug problems. The PX4 logger module is responsible for collecting the information and storing it into the log file. This module is started in the standard startup script with some standard options. The normal approach is to start a log file once the drone has been armed and close it once the drone has been disarmed. The log files are stored in the file system at /data/px4/log.

In some cases it is desirable to start the logs immediately upon the start of PX4. To enable this add the -e option to the logger start line. Care must be used with this option because if power is removed from the drone (e.g. at the end of the flight) then it is possible to corrupt the log file and make it unusable. Instead it is advised to log into the drone via adb or ssh and issue the command px4-logger stop to cause the logger to finish the log file and close it safely before removing power.