PhoneBot uses an old $50 Android smartphone brain with its cameras as eyes — tech Frankenstein is an open source humanoid robot platform for makers

A team of researchers at the University of California, Los Angeles (UCLA) has created a compact humanoid robot called PhoneBot using four inexpensive Android smartphones as its core sensing and computing components. The robot costs around $400 to build, excluding the phones themselves, making it significantly more affordable than other small humanoid research systems on the market.

Standing 483 mm tall and weighing 1.8 kg, PhoneBot uses 13 servo motors to control its legs and rotating torso, relying on the built-in hardware of the smartphones for vision, computing, and control instead of dedicated cameras, motion sensors, and an expensive onboard computer. Each smartphone handles specific tasks such as tracking people, motion sensing, visual detection, and communication with the robot through Wi-Fi.

The researchers trained PhoneBot's walking controller using reinforcement learning in simulation, which helped improve its balance and walking patterns without the need for additional simulated physics steps. Although its current walking controller was trained on flat ground and it lacks arms for object manipulation, PhoneBot remains an open-source project, allowing other researchers to reproduce and modify the platform to explore smartphone-based robotics.