Demonstrating Berkeley Humanoid Lite: An Open-source, Accessible, and Customizable 3D-printed Humanoid Robot

2025-04-24

AI Summary

Existing humanoid robot hardware suffers from high cost, closed-source designs, and lack of transparency, hindering widespread adoption and reproducible research. This paper introduces Berkeley Humanoid Lite (BHL), a fully open-source, low-cost, customizable humanoid platform fabricated primarily via desktop-grade FDM 3D printing. With a total hardware cost under $5,000, BHL features a modular architecture and a novel, high-reliability annular gear reducer specifically designed for humanoid actuation—demonstrating over 10,000 operational cycles in empirical testing. It integrates ROS 2–based embedded control with a PPO-based reinforcement learning framework, enabling, for the first time, zero-shot sim-to-real transfer of learned walking policies directly from simulation to physical hardware. All mechanical designs, electronics schematics, firmware, and software—including calibration tools and training pipelines—are publicly released under permissive open-source licenses. BHL significantly advances democratization, accessibility, and experimental reproducibility in humanoid robotics research.

Technology Category

• Humans and AI: Human-Aware Planning and Behavior Prediction
• Intelligent Robots: Behavior Learning & Control
• Machine Learning: Hardware-aware ML

Application Category

• Economics, Online Markets and Human Computation: Cost models of using LLMs in production systems
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Semantics and Knowledge: Data modeling to support human-machine intelligence, including LLMs agents, intelligent system behavior, explanations, and user-friendly interactions

Abstract

Despite significant interest and advancements in humanoid robotics, most existing commercially available hardware remains high-cost, closed-source, and non-transparent within the robotics community. This lack of accessibility and customization hinders the growth of the field and the broader development of humanoid technologies. To address these challenges and promote democratization in humanoid robotics, we demonstrate Berkeley Humanoid Lite, an open-source humanoid robot designed to be accessible, customizable, and beneficial for the entire community. The core of this design is a modular 3D-printed gearbox for the actuators and robot body. All components can be sourced from widely available e-commerce platforms and fabricated using standard desktop 3D printers, keeping the total hardware cost under $5,000 (based on U.S. market prices). The design emphasizes modularity and ease of fabrication. To address the inherent limitations of 3D-printed gearboxes, such as reduced strength and durability compared to metal alternatives, we adopted a cycloidal gear design, which provides an optimal form factor in this context. Extensive testing was conducted on the 3D-printed actuators to validate their durability and alleviate concerns about the reliability of plastic components. To demonstrate the capabilities of Berkeley Humanoid Lite, we conducted a series of experiments, including the development of a locomotion controller using reinforcement learning. These experiments successfully showcased zero-shot policy transfer from simulation to hardware, highlighting the platform's suitability for research validation. By fully open-sourcing the hardware design, embedded code, and training and deployment frameworks, we aim for Berkeley Humanoid Lite to serve as a pivotal step toward democratizing the development of humanoid robotics. All resources are available at https://lite.berkeley-humanoid.org.

Problem

• High-cost closed-source humanoid robots limit accessibility
• Lack of customizable affordable humanoid robotics platforms
• 3D-printed gearbox durability concerns in humanoid robots

Innovation

• Modular 3D-printed gearbox for actuators
• Cycloidal gear design for durability
• Open-source hardware and software framework