Nineteen humanoid robots waltzed with human partners in Shanghai this week. The interesting problem isn't the dancing. It's the partner. 🤖
Choreography alone is solvable, a robot executing a fixed sequence on a flat stage is a well-understood control problem.
But adding a human changes the category. A partner applies unpredictable forces through the arms and torso, arrives fractionally early or late & shifts weight in ways no script anticipates.
To the robot, that's a continuous stream of disturbances it has to reject while staying upright, in sync with music & in position on a crowded stage.
Balance under unmodelled contact is the same problem that stops humanoids working in warehouses and homes.
Objects shift, floors slip, people bump into things. A stage with a human partner is a rare public test of exactly that.
The hardware: Unitree H2, 180 cm, roughly 70 kg, 31 degrees of freedom, leg joints rated to 360 newton-metres, onboard compute scaling to 2,070 TOPS on Nvidia's Jetson AGX Thor. The eyes are cameras.
Unitree says the routines ran autonomously in real time. That means no teleoperation & no remote correction, not improvisation.
The choreography was learned in advance; what's live is the balance & synchronization.
Nineteen machines holding that simultaneously, in front of an audience, with no single failure visible, is the real measurement worth noting here. 📐
"If we could have devised an arrangement for providing everybody with music in their homes, perfect in quality, unlimited in quantity, suited to every mood, and beginning and ceasing at will, we should have considered the limit of human felicity already attained."