Get the current value of a drone state or setting

Objective:

Query the current value of the “maximum tilt” drone’s setting with the olympe.Drone.get_state() method.

A little explanation first

When the maximum tilt drone setting is changed by the Olympe controller with the MaxTilt() command message, the drone sends the MaxTiltChanged() event message in response.

Note

Changing a drone setting is demonstrated in the following example. We’re just here interested in getting the current drone setting.

When Olympe connects to a drone, it also asks the drone to send back all its states and settings messages. Olympe can later provide with this information through the olympe.Drone.get_state() method. Thus, with Olympe connected to the drone, olympe.Drone.get_state() always returns the current drone state associated to the event message in question.

For this example, we use the MaxTiltChanged() message passed to the olympe.Drone.get_state() method. This will return a dictionary of the MaxTiltChanged() event message which provides the following parameters:

MaxTiltChanged Parameters:

  • current (float) – Current max tilt

  • min (float) – Range min of tilt

  • max (float) – Range max of tilt

Note

The “min” and “max” parameters are actually the minimum and the maximum values for the “maximum tilt” setting. Here, we are only interested in the “current” value of this setting.

Let’s get down to some practice! First, reset the simulation: sphinx-cli action -m world fwman world_reset_all in a terminal.

Copy paste the following Python maxtilt_get.py script somewhere in your directory:

Body

Once Olympe is connected to the drone, the drone sends its states and settings event messages voluntarily. The last state related to the maximum tilt is stored internally. So requesting drone.get_state(MaxTiltChanged)["current"] will retrieve the current (i.e. last remembered) value of maximum tilt.

Except for this example purpose, there is no need to ask for it, since it is a setting the drone naturally sends itself at connection.

Execution

To execute this script and see the maximum tilt value set, run the following command from the shell you’ve just sourced:

(olympe-python3) $ python ./maxtilt_get.py

This should print the current maximum tilt value in your terminal.