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Install ROS 2 on the Modalix SoM DevKit

Use this guide to install Robot Operating System 2 (ROS 2) on the Modalix SoM DevKit and understand how it fits physical AI workloads.

What is ROS 2?​

ROS 2 is the second-generation Robot Operating System, an open-source set of software libraries and tools for building robot and physical AI applications. It is not a monolithic operating system. It is a middleware layer that runs on Linux and lets independent robot processes, such as sensors, actuators, perception models, planners, and controllers, discover one another and exchange data.

Key features include:

  • Node-based architecture. Each capability (a camera driver, a detector, a motor controller, a SLAM stack) runs as an independent node. Nodes are composed at runtime, so the same perception node can be reused across very different robots.
  • DDS-based communication. ROS 2 builds on the Data Distribution Service (DDS) standard for real-time, peer-to-peer pub/sub messaging with configurable Quality-of-Service (reliability, durability, deadline, liveliness) — a hard requirement for safety-critical and time-sensitive robotics.
  • Standard message types. A large catalog of common message definitions (sensor_msgs, geometry_msgs, nav_msgs, vision_msgs, etc.) lets perception, planning, and control components from different vendors interoperate without custom glue code.
  • Cross-platform and real-time friendly. ROS 2 runs on Linux, supports ARM64 and x86_64, and is designed to coexist with real-time kernels and microcontroller stacks (micro-ROS).
  • Rich tooling ecosystem. rviz2 for 3D visualization, rqt for introspection, rosbag2 for recording and replaying sensor streams, and ros2 launch for declarative system bring-up.

Why run ROS 2 on the Modalix SoM?​

Physical AI systems, including autonomous mobile robots, drones, robotic arms, AMRs, and smart cameras with actuation, need both high-throughput neural inference and a deterministic software fabric for sensors, control, and safety. The Modalix SoM supports that combination:

  • Offload perception to the MLA, keep ROS 2 on the Arm cores. Perception nodes (object detection, segmentation, depth, pose, BEV fusion) can call into the MLSoC's MLA, while ROS 2 publishers forward the results as standard vision_msgs or sensor_msgs — no proprietary IPC required.
  • Single board, full stack. Camera ingest, ML inference, ROS 2 middleware, planning, and motor control can all run on the same Modalix SoM, reducing the need for a separate companion compute board.
  • Power-efficient edge deployment. Modalix's performance-per-watt envelope supports battery-powered platforms such as drones, AMRs, and handheld inspection units.
  • eLxr Debian base. The Modalix SoM runs an eLxr Debian-derived runtime, so standard ROS 2 apt packages install cleanly — no cross-compilation or custom Yocto layers needed for the common case.

Prerequisites​

info

ROS 2 installation on the Modalix SoM requires SDK release 2.1.0 or higher running on the eLxr runtime. To check or convert the runtime, see Convert to eLxr.

You also need:

  • A Modalix SoM DevKit powered on and reachable over the network or serial console.
  • sima-cli installed on the DevKit.
  • An active internet connection on the DevKit for package download.

Install ROS 2​

sima-cli provides an installer that pulls the correct ROS 2 distribution for the Modalix SoM, configures the apt sources, and installs the base packages and standard tooling.

Step 1. Install ROS 2 via sima-cli

From the Modalix shell, run:

sima@modalix:~$ sima-cli install tools/ros2

The installer:

  • Add the required Debian bookworm and ROS 2 apt sources, along with the ROS signing key.
  • Install build dependencies (cmake, colcon, vcstool), Qt and OpenCV development packages, the GStreamer plugin set, and the other libraries required to build and run ROS 2 nodes on the SoM.
  • Install the ros2 and colcon packages.
  • Append source /usr/local/ros2/local_setup.bash to /home/sima/.bash_profile so the ROS 2 environment is loaded automatically on every login, and source it for the current shell.
Step 2. Verify the Installation

After sima-cli install tools/ros2 finishes, the ROS 2 environment is sourced in the current shell. Confirm the ros2 CLI is on the path:

sima@modalix:~$ ros2

Then run the standard talker/listener demo across two shells to confirm the DDS middleware is working end-to-end:

sima@modalix:~$ ros2 run demo_nodes_cpp talker

In a second shell on the same device:

sima@modalix:~$ ros2 run demo_nodes_py listener

The listener should print I heard: [Hello World: N] messages as the talker publishes them. ROS 2 is ready to host perception, planning, and control nodes alongside SiMa.ai ML pipelines on the Modalix SoM.