semubot_ros_control

ros2_control hardware interface and velocity controller for the SemuBot 3-motor omnidirectional wheelbase.

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Overview

semubot_ros_control integrates the SemuBot omnidirectional wheelbase into the standard ros2_control framework. It provides:

• A custom ros2_control hardware interface (SemuBotHardwareInterface)
• A custom omnidirectional velocity controller (SemuBotVelocityController)
• Transport variants: USB CDC serial and micro-ROS over UART/USB
• Optional ROS-side PID experiments

The package is part of the broader SemuBot project — a humanoid robot platform.

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Architecture

The active stack is ros2ctrl-microros: ros2_control running on the PC with micro-ROS handling low-level control on the STM32.

/cmd_vel  (geometry_msgs/Twist)
    │
    ▼
SemuBotVelocityController
    │
    ▼
ros2_control command interfaces
    │
    ▼
SemuBotHardwareInterface
    │
    ▼
/hardware_interface/velocity_cmd  (std_msgs/Float32MultiArray)
    │  data = [M1, M2, M3]  — PWM duty commands
    ▼
STM32 micro-ROS agent
    │
    ▼
PWM → motors

Encoder feedback flows in the opposite direction:

STM32 encoders
    │
    ▼
/motor_states  (std_msgs/Float32MultiArray)
    │
    ▼
SemuBotHardwareInterface
    │
    ▼
ros2_control state interfaces
    │
    ▼
SemuBotVelocityController

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Topics

Subscribed

Topic	Type	Description
/cmd_vel	geometry_msgs/Twist	High-level velocity command
/motor_states	std_msgs/Float32MultiArray	Per-motor encoder feedback from STM32

Published

Topic	Type	Description
/hardware_interface/velocity_cmd	std_msgs/Float32MultiArray	Low-level motor commands [M1, M2, M3]

/cmd_vel field mapping

Field	Meaning
linear.x	Forward / backward
linear.y	Left / right (strafe)
angular.z	Rotation

Note: In the current ros2ctrl-microros stack, /hardware_interface/velocity_cmd carries PWM duty cycle values, not wheel velocity targets.

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Dependencies

• ROS 2 Jazzy (or later)
• ros2_control / ros2_controllers
• micro_ros_agent (for micro-ROS transport variant)
• geometry_msgs, std_msgs
• STM32 firmware: SemuBot-Firmware

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Building

cd ~/ros2_ws/src
git clone https://github.com/SemuBot/semubot_ros_control.git
cd ~/ros2_ws
rosdep install --from-paths src --ignore-src -r -y
colcon build --packages-select semubot_ros_control
source install/setup.bash

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Usage

Launch the full stack

ros2 launch semubot_ros_control semubot_control.launch.py

Send a velocity command manually

ros2 topic pub /cmd_vel geometry_msgs/msg/Twist \
  "{linear: {x: 0.2, y: 0.0, z: 0.0}, angular: {z: 0.0}}"

Monitor motor commands

ros2 topic echo /hardware_interface/velocity_cmd

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Integration Variants

Variant	Transport	PID location	Status
1	Serial CDC	STM32	Working
2 (active)	micro-ROS	STM32	Working — recommended
3	Serial CDC	ROS 2	Working
4	micro-ROS	ROS 2	Working

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Repository Structure

semubot_ros_control/
├── include/semubot_ros_control/
│   ├── semubot_hardware_interface.hpp
│   └── semubot_velocity_controller.hpp
├── src/
│   ├── semubot_hardware_interface.cpp
│   └── semubot_velocity_controller.cpp
├── launch/
│   └── semubot_control.launch.py
├── config/
│   └── joy_config.yaml
│   └── semubot_controllers.yaml
├── CMakeLists.txt
├── package.xml
└── README.md

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Related Packages

Package	Description
semubot_description	URDF and mesh assets
semubot_bringup	Top-level launch files
SemuBot-Firmware	STM32 firmware (FreeRTOS, micro-ROS)
semubot_driver	Low-level serial driver utilities

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License

This project is licensed under the Apache 2.0 license - see the LICENSE file for more information.