The PX4 flight stack is a collection of guidance, navigation and control algorithms for autonomous drones. It includes controllers for fixed wing, multirotor and VTOL airframes as well as estimators for attitude and position.
The diagram below shows an example implementation of the typical blocks. Depending on the vehicle some of these can be also combined into a single application (e.g. when a model predictive controller for a specific vehicle is wanted).
{% mermaid %} graph TD; pos_ctrl-->att_ctrl; att_ctrl-->mixer; inertial_sensors-->attitude_estimator; inertial_sensors-->position_estimator; GPS-->position_estimator; computer_vision-->position_estimator; position_estimator-->navigator; position_estimator-->attitude_estimator; position_estimator-->pos_ctrl; attitude_estimator-->att_ctrl; {% endmermaid %}