Learn ROS from web http://wiki.ros.org/ ©️

roscpp is a C++ implementation of ROS. It provides a client library that enables C++ programmers to quickly interface with ROS Topics, Services, and Parameters. roscpp is the most widely used ROS client library and is designed to be the high-performance library for ROS.

• ros::init() : A version of ros::init() must be called before using any of the rest of the ROS system.
• ros::NodeHandle : Public interface to topics, services, parameters, etc.
• ros::master : Contains functions for querying information from the master
• ros::this_node : Contains functions for querying information about this process' node
• ros::service : Contains functions for querying information about services
• ros::param : Contains functions for querying the parameter service without the need for a ros::NodeHandle
• ros::names : Contains functions for manipulating ROS graph resource names

Many examples of using ROS can be found on the wiki and in the roscpp_tutorials package.

PX4 consists of two main layers: the flight stack is an estimation and flight control system, and the middleware is a general robotics layer that can support any type of autonomous robot, providing internal/external communications and hardware integration.

All PX4 airframes share a single codebase (this includes other robotic systems like boats, rovers, submarines etc.). The complete system design is reactive, which means that:

• All functionality is divided into exchangeable and reusable components
• Communication is done by asynchronous message passing
• The system can deal with varying workload

The diagram below provides a detailed overview of the building blocks of PX4. The top part of the diagram contains middleware blocks, while the lower section shows the components of the flight stack.

The 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 following diagram shows an overview of the building blocks of the flight stack. It contains the full pipeline from sensors, RC input and autonomous flight control (Navigator), down to the motor or servo control (Actuators).