Minimal ROS 2 real-time cookbook recipes

Collection of ROS 2 minimal examples showing how to leverage different POSIX and ROS 2 features to create real-time applications.

• minimal_memory_lock: shows how to lock the process memory to avoid memory page faults
• minimal_scheduling: shows how to configure the thread(s) scheduling policy and priority
• minimal_cpu_affinity: shows how to set the process and threads CPU affinity

TODO: Add other packages after review (currently in rolling-experimental branch):

• minimal_realtime_loop: shows different approaches to created typical real-time time based loops
• minimal_deadline_qos: shows how to use the DDS deadline QoS policy
• minimal_lifecycle: shows how to use node lifecycle to separate configuration and runtime real-time phases
• minimal_memory_check: shows how use verify that functions used in the real-time path does not allocate dynamic memory
• minimal_memory_allocator: shows how to use different memory strategies to avoid dynamic memory allocations during the runtime phase
• minimal_loaned_messages: shows how to use loaned messages APIs
• minimal_data_sharing: shows how to use different data sharing approached to avoid blocking calls when sharing data between real-time and non real-time threads
• minimal_dds_tuning: shows how to use DDS specific configurations to tune real-time related settings (TODO: add XML profiles for more DDS implementations)

Requirements

• ROS 2 rolling release
• Linux based operating system (RT_PREEMPT is not mandatory to run the examples)
• Privileges to set priority, scheduling and memory lock limits. This can be achieved by having root privileges or adding user privileges to /etc/security/limits.conf

Build instructions

Create workspace

$ mkdir -p ros2_realtime_examples_ws/src
$ cd ros2_realtime_examples_ws/src
$ git clone https://github.com/ros-realtime/ros2-realtime-examples.git
# Optional: Build rmw_iceoryx for zero-copy examples
$ git clone https://github.com/ros2/rmw_iceoryx

Install dependencies

Use rosdep to install the required dependencies:

$ cd ros2_realtime_examples_ws
$ rosdep install --from-paths src/ --ignore-src --rosdistro=rolling

Build

Build examples

$ cd ros2_realtime_examples_ws
$ colcon build

Note: Some examples might require to install additional RMW implementations