Quadruped Robot

A ROS 2 powered 12-DOF quadruped robot built using hobbyist PWM servos, a Raspberry Pi 4B, and a custom lightweight plastic frame. The project focuses on gait generation, robot stability, motion control, and real-world embedded robotics using ROS 2 Jazzy running inside Docker.

Robot Overview

Hardware Specifications

• 12x 30kg PWM Servos

  • 3 DOF per leg
  • Hobbyist-grade high torque servos

• Frame

  • Lightweight plastic frame
  • Modular leg structure

• Controller

  • Raspberry Pi 4B (4GB RAM)

• PWM Driver

  • PCA9685 16-channel PWM controller

• Battery

  • 5200 mAh 2S LiPo battery

• Software Stack

  • ROS 2 Jazzy
  • Docker-based development environment

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Features

• ROS 2 based robot architecture
• Modular gait generation system
• Bézier curve based foot trajectories
• Support for multiple walking gaits
• PWM servo control through PCA9685
• Dockerized development workflow
• Gazebo simulation support
• IMU integration for balancing and stability control
• Extensible node-based control architecture

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Project Structure

src/
├── control_pkg/
├── interfaces/
├── launch_pkg/
├── balance_pkg/
├── pca9685_driver/
└── initialize.sh
README.md
.gitignore

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Software Architecture

The robot software is organized into several ROS 2 nodes:

Node	Purpose
Control Node	Handles gait execution and joint commands
Balance Node	Processes IMU data for stabilization
PCA9685	Communicates with PCA9685 and servos

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Gait System

The quadruped uses a phase-based gait controller with configurable:

• Gait frequencies
• Phase offsets
• Swing and stance trajectories
• Bézier control points
• Interpolated gait transitions

Supported and planned gaits include:

• Stand
• Walk
• Trot
• Turning motions
• Dynamic gait transitions

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Simulation

The project includes Gazebo simulation support using ROS 2 control interfaces.

Simulation features include:

• Joint trajectory control
• IMU simulation
• Robot state publishing
• Controller manager integration
• Real-time gait testing

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Development Goals

This project is intended as both:

• A research and learning platform for quadruped locomotion
• A fully functional embedded robotics system

Areas of focus include:

• Robotics software architecture
• Control systems
• Embedded Linux
• ROS 2
• Real-time motion control
• Simulation and testing
• Hardware/software integration

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License

This project is licensed under the MIT License.