UCLA builds a $400 walking robot that runs on a smartphone Other

UCLA researchers built PhoneBot, a 48 cm walking robot that uses an ordinary Android phone as its eyes, balance sensor and computer. The parts cost about $400 without the phone, and the designs are open source.

The paper came out on arXiv on October 6, 2026, from UCLA's Robotics and Mechanisms Laboratory (RoMeLa). Similar-size humanoids the authors compare it with cost $3,500 (HighTorque MiniPi) to $13,800 (ROBOTIS OP3).

How it works

• The phone does the thinking. Its gyroscope and accelerometer keep balance, its camera is the robot's eyes, and its processor runs the walking network.
• Wi-Fi to the legs. The phone sends target joint positions over Wi-Fi to a small onboard computer, which passes them to the motors. The phone has no wired connection to the robot.
• 13 motors. DYNAMIXEL XL430 servos at $23.90 each: six in each leg and one that turns the torso, so the camera can follow a person without turning the whole robot.
• On the phone: walking and stand-up control, person and pose detection, and room mapping.
• Off the phone: speech recognition and the language model run on a separate laptop. The phone records speech and plays the reply.

The specs

Phones tested

The robot walked, stood up after lying face down, and followed a person.

Mapping did not run on the Honor 9 because Google services are not available on that phone in the US.

Limits and plans

PhoneBot has no arms, has learned to walk only on flat floors, and its cheap motors limit what it can carry and how fast it can move. Next the team plans lightweight arms, walking on uneven ground, and running a language model on the phone itself.

Sources

• arXiv: PhoneBot: A Low-Cost Open Humanoid Robot Platform Reusing Smartphones
• PhoneBot project page