UCLA's PhoneBot humanoid reuses old Android phones as a $400 robot brain

Reported by Hackster.io News on 2026-10-10. Summarized and analyzed by XAIPART Editorial.

What happened

Researchers at UCLA have released PhoneBot, an open-source humanoid robot that uses an ordinary Android smartphone as its main computer and sensor suite. ^S1 The platform is positioned as a low-cost reuse of consumer-grade hardware that already integrates a processor, camera, inertial measurement unit, and wireless connectivity. ^S1

The reported build stands approximately 19 inches tall, weighs four pounds, and costs around $400 to build excluding the smartphone. ^S1 PhoneBot does not include arms or a head, but the source states it can walk on two legs, track people with its camera, and recover after falling. ^S1

The lower body has 12 degrees of freedom across three joints at each hip, one at each knee, and two at each ankle, plus a thirteenth torso joint that rotates the phone mount without moving the feet. ^S1 All 13 joints use DYNAMIXEL XL430-W250-T servo motors, and a small onboard computer relays Wi-Fi commands from the phone to the servos. ^S1 A custom Android app runs the control and movement networks with TensorFlow Lite. ^S1

The researchers validated the design with four Android phones, including a 2017 Honor 9 and three budget models costing approximately $50 to $80 each. ^S1 For locomotion, they trained a controller with reinforcement learning in simulation and added a sagittal-mirroring technique that cut left-right joint-angle asymmetry from 0.254 to 0.003 radians. ^S1 Conversational AI processing still requires an external laptop, and the walking controller was only trained on flat terrain. ^S1

Corrections: none at publication. This brief will be updated with a timestamp if the source corrects its report.