UCLA lab builds PhoneBot, a 48 cm walking robot that runs on an old Android phone and about $400 of parts

UCLA's Robotics and Mechanisms Laboratory (RoMeLa) described PhoneBot in an arXiv preprint posted on Oct 6: a 48.3 cm, 1.8 kg two-legged robot whose torso-mounted smartphone supplies the camera, motion sensor and computing, running the walking policy on the phone and sending joint targets over Wi-Fi to a small onboard computer.

The lab puts the hardware cost at about $400 excluding the phone, against $13.8K for ROBOTIS OP3 in the paper's comparison table; the 13 DYNAMIXEL XL430 servos at $23.90 each come to $310.70, or roughly 78% of that budget by MEKAWIRE calculation.

The team, led by Dennis Hong, tested four phones including a 2017 Honor 9 and three prepaid models bought for $50 to $80, and published the design as open source; speech recognition and the language model still run on a laptop, and the robot has no arms.

ZDNet Korea carried the work on Oct 17. At 48 cm PhoneBot sits far below the 140 cm line the International Federation of Robotics used when it counted about 7,000 full-size humanoids sold in 2025, which MEKAWIRE reported on Sept 30, so it is a teaching and research platform rather than a rival to commercial humanoids.