Physical AI: Hardware, Economy, and the Humanoid Race

The article argues for humanoid robots based on the world being designed for human bodies, reducing the need for environmental redesign. It details three actuator schools: harmonic drives (precise but fragile), quasi-direct drive (QDD, robust but lower torque), and planetary roller screws (strong but expensive). Robot hands remain a critical frontier, with companies like Tesla, 1X, and Figure pushing for more degrees of freedom and tactile sensing. Battery life is limited to 2–4 hours, requiring hot-swap stations as demonstrated by UBTech's Walker S2. Prices range from $16,000 for Unitree's G1 to hundreds of thousands for Western industrial robots. Commercial deployments are primarily in warehouses and factory logistics: Agility Robotics' Digit operates at a GXO warehouse under a robot-as-a-service model; Figure's robots assemble car bodies at BMW; Apptronik works with Mercedes-Benz; Boston Dynamics tests electric Atlas at Hyundai plants. All are still at pilot scale, but economics are promising: a $100,000 robot working two shifts costs $6–8/hour vs. $25–30/hour for human labor. Home robots, like 1X's NEO, remain heavily teleoperated and slow, with experts noting that complex tasks are often performed by remote human operators. China produces cheaper robots (Unitree G1 at $16,000) and leads in production scale.