bot_description

bot_description - Robot Model & Transform Publishing

Robot description package providing URDF/XACRO models and transform publishing for the BotBrain robot system. This package manages the robot's kinematic model, visualization meshes, and publishes the robot state to the TF tree for navigation and control.

Purpose

The bot_description package provides the robot's mechanical and visual description to the ROS2 ecosystem. It manages:

• Robot URDF/XACRO model definitions
• 3D visualization meshes for RViz
• Robot state publishing (joint states to TF transforms)
• Static transforms between robot components
• Integration of robot hardware model with BotBrain interface module

Package Files

Launch Files

launch/description.launch.py

Main description launcher that orchestrates the complete robot model:

What it launches:

1. robot_description.launch.py: Robot hardware model (e.g., Unitree Go2 quadruped)
2. botbrain_description.launch.py: BotBrain interface module model (cameras, sensors)
3. static_transform_publisher: Links robot base to BotBrain module (interface_link to botbrain_base)

Configuration:

• Reads robot_config.yaml from workspace root
• Uses robot_name field for namespace and TF frame prefixes

Usage:

ros2 launch bot_description description.launch.py

This is typically launched automatically by bot_bringup during system startup.

launch/robot_description.launch.py

Publishes the robot hardware URDF model and robot state:

Nodes:

• robot_state_publisher: Converts URDF to TF transforms
• Publishes robot joint states to /robot_description topic
• Provides forward kinematics for the robot base

Model Source:

• Loads XACRO file for the specific robot platform
• Supports different robot models (Go2, Tita, etc.)

launch/botbrain_description.launch.py

Publishes the BotBrain module URDF model:

Nodes:

• robot_state_publisher: Publishes BotBrain module transforms
• Includes camera mounts, sensor positions, and interface links
• Provides mounting geometry for perception sensors

Integration:

• BotBrain module is linked to robot hardware via static transform
• Transform published from robot interface_link to botbrain_base

XACRO Files

Located in xacro/ directory:

xacro/botbrain.xacro

XACRO model defining the BotBrain interface module:

Includes:

• Interface mounting link
• Camera mount positions (D435i, D455)
• Sensor mounting points
• Module geometry and collision meshes

Parameters:

• Configurable mounting offsets
• Camera positioning and orientation
• Sensor frame definitions

Meshes

Located in meshes/ directory:

Contents:

• 3D visualization meshes for RViz
• STL or DAE format mesh files
• Robot and module visual geometry
• Collision geometry for motion planning

Usage:

• Referenced by URDF/XACRO files
• Loaded by RViz for visualization
• Used by collision detection systems

Topics

Published

• /{namespace}/robot_description (std_msgs/String) - Complete robot URDF
• /tf_static (tf2_msgs/TFMessage) - Static transforms
• /tf (tf2_msgs/TFMessage) - Dynamic transforms (from joint states)

Subscribed

• /{namespace}/joint_states (sensor_msgs/JointState) - Robot joint positions (if available)

Directory Structure

bot_description/
├── launch/
│   ├── description.launch.py           # Main launcher
│   ├── robot_description.launch.py     # Robot hardware model
│   └── botbrain_description.launch.py  # BotBrain module model
├── xacro/
│   └── botbrain.xacro                  # BotBrain XACRO model
├── meshes/
│   └── [mesh files]                    # 3D visualization meshes
├── CMakeLists.txt                      # Build configuration
└── package.xml                         # Package manifest

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