![ROS 2
What is ROS 2?
● 2nd generation of Robotic Operating System, provides infrastructure for
robotics developers
● Open-source software with large community underneath
● [Long story short] Communication based on pub/sub paradigm:
○ Sensors publish to topics & actuators subscribe to topics
○ Based on DDS (Data Distribution System middleware)
○ Each node runs its own independent process
● Modular
● Benefits of QoS
● Has its own build/launch system
● CLI tools for deployment, monitoring and debugging
● Runs on Linux, Windows](https://image.slidesharecdn.com/erf2021francescafinocchiaro-210422104345/85/micro-ROS-bringing-ROS-2-to-MCUs-5-320.jpg)
![C99 library:
provides utility functions for creating
nodes, publishers, subscribers &
redesigned executor [deterministic and
LET semantics, dynamic memory
allocation only at startup,
domain-specific scheduling ]
RCL, RCUtils,
rosidl_typesupport
RCLCPP, RCLPY
App
RCL, RCUtils,
rosidl_typesupport
RCLC
App
Same as in ROS 2
(many functionalities not used)
ROS Client Support Libraries](https://image.slidesharecdn.com/erf2021francescafinocchiaro-210422104345/85/micro-ROS-bringing-ROS-2-to-MCUs-12-320.jpg)
![● Implemented using Micro XRCE-DDS middleware in lower layer
● Allows static configuration of memory resources
Micro XRCE-DDS
configurable parameters
Transport
[UDP, serial, custom] Agent IP Agent Port
Creation mode
[XML, Ref]
IP version
[IPv4 - IPv6]
Max History
Max Nodes
Max Publishers Max Subscriptions Max Clients Max Services Max Topics
Node name max length Topic name max length
Type name max length
micro-ROS
configurable
parameters
Configurability of these parameters allows preconfiguring the size of the library
and tuning the size of the buffer to the memory available
RMW](https://image.slidesharecdn.com/erf2021francescafinocchiaro-210422104345/85/micro-ROS-bringing-ROS-2-to-MCUs-30-320.jpg)
micro-ROS: bringing ROS 2 to MCUs
- 1. Workshop: “Deeply embedded software” Program Francesca Finocchiaro (eProsima) - “micro-ROS: bringing ROS 2 to microcontrollers” Jan Staschulat (Bosch Research) - “micro-ROS: API and executor” Anaëlle Sarazin (WYCA Robotics) - “Elodie and micro-ROS” Tomasz Rokosz (Hydra System) - “micro-ROS enabled GNSS receiver” --- Panel discussion - Invited panelists: Pablo Garrido Sanchez (eProsima), Alexandre Malki (PIAP)
- 2. micro-ROS: bringing ROS 2 to MCUs Francesca Finocchiaro - eProsima April 13th, 2021
- 3. Overview
- 4. funded by Open-source project, now benefiting from a huge participation from a growing community! https://micro-ros.github.io/ https://www.eprosima.com/ francescafinocchiaro@eprosima.com Who are we?
- 5. ROS 2 What is ROS 2? ● 2nd generation of Robotic Operating System, provides infrastructure for robotics developers ● Open-source software with large community underneath ● [Long story short] Communication based on pub/sub paradigm: ○ Sensors publish to topics & actuators subscribe to topics ○ Based on DDS (Data Distribution System middleware) ○ Each node runs its own independent process ● Modular ● Benefits of QoS ● Has its own build/launch system ● CLI tools for deployment, monitoring and debugging ● Runs on Linux, Windows
- 6. micro-ROS: puts ROS 2 onto microcontrollers! A solution for creating ROS 2 nodes into embedded devices micro-ROS
- 7. Highlights ● Layer-compatible with ROS 2 ● Integrated into ROS 2 ecosystem ● Allows to create a ROS 2 node with ~ all functionalities ● Client/server logics ● Fully customizable transports ● Runs on a variety of different platforms thanks to platform-versatile cross-compilation tools ● Supporting ROS 2 Foxy, Rolling and soon Galactic! ● A growing community! Why micro-ROS
- 8. ROS 2 micro- ROS micro-ROS architecture
- 9. ROS 2 micro- ROS micro-ROS architecture
- 10. Micro XRCE-DDS: DDS for eXtremely Resource-Constrained Environments. Clients - XRCE entities on low-resource consumption devices. Agent - XRCE entity connected with DDS global data space. Acts on behalf of Clients in the DDS world. Main features: ● Client-server architecture ● Request-response pattern ● Connection oriented Middleware architecture
- 11. ROS 2 micro- ROS micro-ROS architecture
- 12. C99 library: provides utility functions for creating nodes, publishers, subscribers & redesigned executor [deterministic and LET semantics, dynamic memory allocation only at startup, domain-specific scheduling ] RCL, RCUtils, rosidl_typesupport RCLCPP, RCLPY App RCL, RCUtils, rosidl_typesupport RCLC App Same as in ROS 2 (many functionalities not used) ROS Client Support Libraries
- 15. Target: mid-range microcontrollers. Currently supported: ● ARM-M3/M4/M7 MCUs ● Xtensa MCUs ● RISC-V Typical features: ● ~ 1 MB of flash memory ● ~ 100 kB of RAM memory ● < 500 mA consumption ● General purpose input/output pins (GPIO) ● Communication peripherals: USB, Ethernet, SPI, UART, I2C, CAN, etc. Supported HW
- 16. Arduino Due/Zero OpenCR 1.0 Olimex LTD STM32-E407 Crazyflie 2.1 drone ST Nucleo family STM32L4 Discovery kit IoT ESP32 family Teensy 3.2/4.1 Arduino Portenta Supported HW Raspberry Pi Pico
- 17. micro-ROS Zephyr module micro-ROS Arduino micro-ROS ESP-IDF component Integration into external tools micro-ROS STMCube
- 19. my_custom_transport_open(...) my_custom_transport_close(...) my_custom_transport_write(...) my_custom_transport_read(...) Versatile API for custom transports micro-ROS provides user API for interfacing with lowest level transport layer at runtime This enables to implement custom transports and allows to transmit DDS-XRCE wire protocol over virtually any protocol, network or communication mechanism. 4 functions must be implemented:
- 20. Continuous fragment mode micro-ROS Client Transport buffer Allows to send up to 64 kB according to DDS-XRCE specification Publisher writes on the run (continuously) MTU To the micro-ROS Agent message fragmentation serialization
- 21. Client-to-Agent Ping micro-ROS Client micro-ROS Agent establish session request operation operation reply Ping to see if Agent is alive Pong reply Pings Pongs (if alive)
- 22. Shared Memory micro-ROS Client micro-ROS Agent Pub creation Sub creation Publisher Subscriber Matching info Internal mechanism for matching entities within Client Entities match within the Agent by default
- 23. Static Memory Pools in the RMW
- 24. Client-Agent time sync micro-ROS Client micro-ROS Agent epoch relative time Client inherits epoch from sync w/ Agent Client requests time offset between clocks
- 25. Demos
- 26. Demo I micro-ROS enabling smart warehouses duties
- 27. Demo II ROS 2 to micro-ROS TCP tunneling via Integration Service!
- 28. Thanks for your attention!
- 29. Back-up slides
- 30. ● Implemented using Micro XRCE-DDS middleware in lower layer ● Allows static configuration of memory resources Micro XRCE-DDS configurable parameters Transport [UDP, serial, custom] Agent IP Agent Port Creation mode [XML, Ref] IP version [IPv4 - IPv6] Max History Max Nodes Max Publishers Max Subscriptions Max Clients Max Services Max Topics Node name max length Topic name max length Type name max length micro-ROS configurable parameters Configurability of these parameters allows preconfiguring the size of the library and tuning the size of the buffer to the memory available RMW
- 31. Continuous fragment mode XRCE Client XRCE Agent Max: 64 kB according to DDS-XRCE specification Publisher Publisher ... writes on the run
- 32. Static Memory Pooling in RMW micro-ROS Client’s RMW Subscriber ... Subscriber ... Subscriber ... ... Subscriber Subscriber ... Subscriber ...
- 33. Continuous fragment mode micro-ROS Client micro-ROS Agent Up to 64 kB according to DDS-XRCE specification Publisher Publisher ... writes on the run
- 34. Graph manager ● DDS participant scanning the network: provides introspection capabilities to user. ROS 2 topology consumable by micro-ROS ● micro-ROS topology info available to ROS 2 Graph support
- 35. Continuous fragment mode micro-ROS Client Transport buffer Allows to send up to 64 kB according to DDS-XRCE specification Publisher writes on the run (continuously) MTU To the micro-ROS Agent message
- 36. Continuous fragment mode micro-ROS Client Transport buffer Allows to send up to 64 kB according to DDS-XRCE specification Publisher writes on the run (continuously) MTU To the micro-ROS Agent message