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
neck_controller	Head (pan/tilt)	2	/leader/joystick_controller_left
body_controller	Vertical lift	1	/leader/joystick_controller_right
joint_state_broadcaster	All joints	–	Publishes to /joint_states

All controllers (except joint_state_broadcaster) use the JointTrajectoryController type.

By default, all joints operate in position mode.

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

Controller YAML Example (link)

controller_manager:
  ros__parameters:
    update_rate: 100
    arm_l_controller:
      type: joint_trajectory_controller/JointTrajectoryController
    arm_r_controller:
      type: joint_trajectory_controller/JointTrajectoryController
    neck_controller:
      type: joint_trajectory_controller/JointTrajectoryController
    body_controller:
      type: joint_trajectory_controller/JointTrajectoryController
    joint_state_broadcaster:
      type: joint_state_broadcaster/JointStateBroadcaster

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
      - l_rh_r1_joint  # left gripper
    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