Software

Software Overview

AI Worker is a Jetson Orin–based robot platform built for real-world Physical AI research. It supports full-body motion control and enables smooth integration of both teleoperation and AI policy execution.

The platform runs on ROS 2 Jazzy and uses the ros2_control framework for real-time joint-level control. All joints are powered by DYNAMIXEL X, Y, and P series motors connected via a single RS-485 bus, using the Dynamixel SDK. Each joint can operate in either position or current control mode, managed through a unified hardware interface.

This platform is designed for:

• Collecting motion data through teleoperation
• Training reinforcement learning or imitation learning models
• Running AI-generated trajectories in real time without changing system code

It is suitable for researchers, developers, and integrators working with AI-enabled robotics.

System Architecture

The diagram below illustrates the overall control structure of AI Worker.

External teleoperation or trajectory commands are received via ROS 2 topics, processed in real time by ros2_control, and executed by DYNAMIXEL actuators over RS‑485.

Layer	Component	Description
Compute	NVIDIA Jetson AGX Orin 32GB	Jetpack 6.2 + Docker container (ROS 2 Jazzy)
Motion Control	ros2_control	100Hz joint control loop
Actuators	DYNAMIXEL X / P / Y series	Position / Current mode via RS‑485
Communication	U2D2 (RS‑485)	4 Mbps, Dynamixel Protocol 2.0
Networking	Ethernet / Wi-Fi 6	Remote control and AI policy streaming
Sensors (Optional)	Realsense D405 (wrist), ZED Mini (head)	Integrated via official ROS 2 drivers

Why ros2_control?

ros2_control is a real-time, modular control framework used in ROS 2. AI Worker uses it without major changes.

• Separates control logic from hardware drivers
• Operates at a fixed 100Hz update rate
• Supports dynamic loading or replacement of controllers
• Allows AI policies to send trajectory commands using standard ROS topics

This structure supports both manual operation and AI-based control in the same system.

Motion Execution Pipeline

Input Source (Teleoperation / AI Policy)
      ↓
ROS 2 JointTrajectory Topic
      ↓
controller_manager (100Hz)
      ↓
JointTrajectoryController(s)
      ↓
resource_manager (interface arbitration)
      ↓
DynamixelHardwareInterface (position / current)
      ↓
RS‑485 via Dynamixel SDK
      ↓
DYNAMIXEL Actuators

Step-by-Step

1. Trajectory generation — Created by joystick, GUI, or AI model
2. ROS topic publishing — Commands sent to /leader/joint_trajectory_command_broadcaster_*
3. Controller manager — Runs the main read → update → write loop at 100Hz
4. JointTrajectoryController — Splits trajectory and commands each joint
5. Resource manager — Controls access to command interfaces and prevents conflicts between controllers
6. Hardware interface — Converts commands to RS-485 packets using Dynamixel SDK
7. Actuators — Execute the motion and return position/current feedback

Controller Configuration & Joint Mapping

Controller	Segment	DOF	Input Topic
arm_l_controller	Left arm (w/ gripper)	8	/leader/joint_trajectory_command_broadcaster_left
arm_r_controller	Right arm (w/ gripper)	8	/leader/joint_trajectory_command_broadcaster_right
head_controller	Head (pan/tilt)	2	/leader/joystick_controller_left
lift_controller	Vertical lift	1	/leader/joystick_controller_right
joint_state_broadcaster	All joints	–	Publishes to /joint_states
swerve_drive_controller	Mobile base	6	/cmd_vel

All controllers (except joint_state_broadcaster and swerve_drive_controller) use the JointTrajectoryController type.

By default, all joints operate in position mode, except for the mobile base which operates in velocity mode.

The last joint in each arm controller corresponds to the gripper.

Controller YAML Example (link)

/**:
  controller_manager:
    ros__parameters:
      use_sim_time: False
      update_rate: 100  # Hz

      arm_l_controller:
        type: joint_trajectory_controller/JointTrajectoryController

      arm_r_controller:
        type: joint_trajectory_controller/JointTrajectoryController

      head_controller:
        type: joint_trajectory_controller/JointTrajectoryController

      lift_controller:
        type: joint_trajectory_controller/JointTrajectoryController

      joint_state_broadcaster:
        type: joint_state_broadcaster/JointStateBroadcaster

      swerve_drive_controller:
        type: ffw_swerve_drive_controller/SwerveDriveController

/**:
  arm_l_controller:
    ros__parameters:
      joints:
        - arm_l_joint1
        - arm_l_joint2
        - arm_l_joint3
        - arm_l_joint4
        - arm_l_joint5
        - arm_l_joint6
        - arm_l_joint7
        - gripper_l_joint1
      command_interfaces:
        - position
      state_interfaces:
        - position
        - velocity
      allow_nonzero_velocity_at_trajectory_end: true

Debugging & Visualization Tools

Tool / Topic	Description
ros2 control list_controllers	List loaded controllers and their status
/joint_states	Real-time joint position and velocity feedback
RViz2	3D view of robot model (URDF), TF, and movement

Safety & Fault Handling

• Joint limits are enforced using the URDF and controller configuration
• Out-of-range values are clamped by the hardware interface (YAML-defined limits)
• The Dynamixel hardware interface checks for communication errors with each motor