Overview

This section lists the ROS 2 interfaces of each component, with their names, types and QoS. It's a reference to look things up in. Communication channels explains how the components fit together.

Names

Every interface is named relative to the drone's namespace. A drone launched as drone0 publishes platform/info on /drone0/platform/info, and its take-off behavior serves /drone0/TakeoffBehavior. The pages in this section give the names without the namespace.

The TF topics are the exception. /tf and /tf_static are shared by every drone, and each drone's frames carry its namespace instead, like drone0/base_link. Frames explains the tree.

Using the names in code

The standard names are defined once in as2_core, so your code doesn't have to spell them out. In C++ they're constants in the as2_names namespace, from three headers in as2_core/names/:

#include <as2_core/names/topics.hpp>
#include <as2_core/names/services.hpp>
#include <as2_core/names/actions.hpp>

auto sub = node->create_subscription<as2_msgs::msg::PlatformInfo>(
  as2_names::topics::platform::info, as2_names::topics::platform::qos, callback);

The topic header also gives the QoS each group of topics uses. Python has the same names in a module built from the headers, without the QoS:

from as2_core import as2_names

as2_names.topics.platform.info  # 'platform/info'
as2_names.services.platform.set_arming_state  # 'set_arming_state'
as2_names.actions.takeoff  # 'TakeoffBehavior'

The headers only cover the core components and six of the behaviors. The other behaviors and the utilities hard-code their names, which the pages in this section list.

QoS

Aerostack2 uses two QoS profiles for its topics.

A best effort subscriber receives messages from a reliable publisher, but not the other way round. To read a sensor data topic, subscribe with sensor data QoS too, or with rclcpp::SensorDataQoS() in C++ and qos_profile_sensor_data in Python.

Components