Add Zenoh pico support

[PetervdPerk-NXP]

Zenoh is a publish/subscribe protocol supporting peer-to-peer (FMU-to-FMU) and routed communication (FUM-to-Companion/Linux). Zenoh is plug-gable and on Linux it can be bridged to ROS2/DDS through zenoh-plugin-dds.

Zenoh-Pico is an implementation of Zenoh in C for constrained devices, it's fully compatible with the Rust Zenoh implementation.

For serialization of the messages the CycloneDDS CDRSTREAM library is used to generate DDS/ROS2 byte compatible serialization. This is decoupled from Zenoh so that other modules can re-use the serialization library.

Setup (FMU-to-Companion/Linux)

Companion/Linux

• Setup Zenoh version on a Linux system https://github.com/eclipse-zenoh/zenoh#how-to-install-it
  • Tested with zenohd v0.7.0-rc-401-gb9103c3d and zenohd v0.10.0-dev-23-g44875300 (Needed for multicast support)
• Setup Zenoh-plugin-dds on the Linux system https://github.com/eclipse-zenoh/zenoh-plugin-dds#how-to-install-it
  • Tested with zenoh-bridge-dds v0.7.2-rc built with rustc 1.70.0 (90c541806 2023-05-31)
• Start a Zenoh router on the Linux machine connected to your FMU
  • For client mode use zenohd
  • For multicast mode use zenohd -e udp/224.0.0.225:7447 note zenohd v0.10.0-dev-23-g44875300 or newer required
• Start Zenoh dds bridge on the Linux machine zenoh-bridge-dds -m client

FMU

• Enable the Zenoh module on your FMU build CONFIG_DRIVERS_ZENOH.
• Add a uORB topic to published i.e. zenoh config addpublisher sensor_combined sensor
• Start Zenoh zenoh start

Companion/Linux

• Make sure you've got ROS2 installed (in my case I've been testing ROS2 Galactic but newer should also work)
• Clone https://github.com/PX4/px4_msgs and build px4_msgs
• Source ROS2 and compiled px4_msgs
• Type ros2 topic echo sensor px4_msgs/SensorCombined to receive msgs from the FMU

timestamp: 5101022267
gyro_rad:
- 0.00033584635821171105
- 0.001161606633104384
- 0.0029726973734796047
gyro_integral_dt: 4390
accelerometer_timestamp_relative: 0
accelerometer_m_s2:
- -0.1838383674621582
- -0.04610908403992653
- -9.762420654296875
accelerometer_integral_dt: 4390
accelerometer_clipping: 0
gyro_clipping: 1
accel_calibration_count: 1
gyro_calibration_count: 1

Current shortcomings

• Naive CSV file method for storing configuration and publishers/subscribers, would be nice PX4 param system can be expanded to support custom key/value storage i.e. json/xml like.
• No message checking i.e. different versions of PX4 might produce corrupted data
• No rate limiting yet
• No timesync
• FMU-to-FMU communication no distinction between own msgs and from incoming from Zenoh
• Zenoh 0.7.X based protocol, new 0.10.0 upcoming but probably stabilize around Q1 2024
• Documentation, I would consider Zenoh for now to experimental when all stabalizes I think we could add documentation.

[dagar]

This will take a little bit to review, but in the meantime can you get it through CI cleanly?

[PetervdPerk-NXP]

Hm to get Zenoh-pico to build, I think CMake 1.14 is mandatory need to check if CMake 1.13 might work as well.

[dagar]

Hm to get Zenoh-pico to build, I think CMake 1.14 is mandatory need to check if CMake 1.13 might work as well.

We can re-evaluate the actual requirement if you're hitting it somewhere. Some of the older containers might just need a bump.

[Jaeyoung-Lim]

Yay!

[PetervdPerk-NXP]

These are the blocker for moving to CMake 3.14

CI task	Container	CMake version
mavros_mission_tests	px4io/px4-dev-ros-melodic:2021-09-08	3.10.2
mavros_offboard_tests	px4io/px4-dev-ros-melodic:2021-09-08	3.10.2
compile_linux_arm64	px4io/px4-dev-aarch64:2022-08-12	3.13.4
clang-tidy	px4io/px4-dev-clang:2021-09-08	3.10.2

[PetervdPerk-NXP]

Okay CI is successful now, (CMake 3.9 works and rosidl)

I've added 2 targets that can Zenoh and communicate with ROS2

nxp_mr-canhubk3_zenoh
px4_fmu-v6x_zenoh
px4_sitl_zenoh

[dirksavage88]

Okay CI is successful now, (CMake 3.9 works and rosidl)

I've added 2 targets that can Zenoh and communicate with ROS2

nxp_mr-canhubk3_zenoh
px4_fmu-v6x_zenoh
px4_sitl_zenoh

I would be interested if this could work on the fmuk66 target as well since zenoh pico is supposed to be lightweight?

[PetervdPerk-NXP]

I would be interested if this could work on the fmuk66 target as well since zenoh pico is supposed to be lightweight?

Albeit zenoh-pico is lightweight the current implementation might still be too big for the fmuk66.
Probably we could tune the profile by disabling multicast, tune the buffers and take a subset of uORB (currently we can convert all uORB messages to Zenoh and vice-versa).

Personally I would like to develop and improve zenoh-pico for mr-canhubk344 or other bigger targets before moving over to smaller targets.

[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/zenoh-on-px4/35267/2

[uupks]

Hi, i'm facing the problem when i try to make px4_sitl_zenoh.

[  7%] Generating px4/msg/ActionRequest.c, px4/msg/ActionRequest.h
[  8%] Built target cdr
idlc/bin/idlc: illegal option -- f cdrstream-desc
Usage: idlc [OPTIONS] FILE
Try 'idlc -h' for more information.

[PetervdPerk]

That errors seems to indicate there's a problem with a preinstalled version of idlc and then the cmake builds.

[uupks]

it seems like that idlc doesn't support "-f cdrstream-desc" option

[PetervdPerk-NXP]

It does but you've got a "preinstalled" version. Are you by any chance running the px4 build after sourcing ros2?

[uupks]

i build px4_sitl_zenoh with a new shell environment , now it works..

Thanks !!