Made of Plastic, It’s Fantastic

To be at home in our world, robots need to become more like us. For starters, that means they will need a similar form and body mechanics. By walking on two legs and interacting with their environment with a pair of arms and hands, they will be comfortable operating in our homes and workplaces, and they will have what it takes to use existing tools to extend their capabilities. However, despite their obvious advantages, humanoid robots are among the least common types produced.

The primary reasons for the present dearth of humanoid robots are cost and complexity. Wheeled robots, quadcopters, and the like are just much simpler to build, and their designs are far less complex. They also rely on less expensive hardware platforms for operation. These factors have an outsized impact on developers that want to break into the field. Entry-level options are few and far between, keeping them out of the game. And that, in turn, slows forward progress and prevents the technology from rapidly advancing.

A team of engineers at the University of California, Berkeley is working to create a more practical humanoid robotics experimentation platform for people that are just getting started in the field. The result is called Berkeley Humanoid Lite, and it is an open source and customizable robot that is built with user-friendly, off-the-shelf components and 3D-printed parts. For about $5,000 in parts, anyone can build this 3-foot-tall robot in about one week’s time.

Most of the robot’s structure and actuators are 3D-printed, and the other components can be purchased from the usual electronics distributors. Since plastic 3D-printed parts can not take the wear and tear that metal can, the team included a cycloidal gear system inside each actuator. This type of design spreads mechanical loads across a wider area than traditional gears, increasing strength and durability despite the use of plastic parts.

Tests show that these 3D-printed actuators hold up under stress, performing comparably to more expensive, proprietary alternatives. In fact, the researchers have yet to break an actuator in any of their tests, even after running rigorous experiments involving lots of manipulation tasks and bipedal locomotion.

To demonstrate the robot’s capabilities, the team equipped Berkeley Humanoid Lite with a joystick-controlled teleoperation system, allowing it to precisely interact with objects like a Rubik’s Cube. They also trained a reinforcement learning-based controller in simulation and successfully transferred the learned walking policy to the real robot, which is a challenging technique known as a zero-shot policy transfer.

The entire project is fully open source. The hardware designs, embedded software, and training frameworks are freely available to the public at the project website. The researchers have also cultivated an active community on Discord and other platforms, where users can share progress, troubleshoot builds, and exchange ideas.

The Berkeley Humanoid Lite project aims not only to make humanoid robotics more accessible, but to spark broader innovation by lowering the barrier to entry. With this open framework, the hope is that a new generation of roboticists will help advance the field in the near future.