In the humanoid robotics race, all eyes are on the “brain”, the embodied AI model that reasons, reacts, and adapts. But beneath the surface, a quieter battle rages over the robot’s “physique” and “cerebellum”: the actuators, screws, and gearboxes that convert thinking into movement. And far from being solved, hardware may now be the biggest bottleneck of all. This is partly because Chinese manufacturers like Unitree and Engine AI have showcased humanoids capable of dancing, jumping, performing martial arts, and even doing somersaults at remarkably low cost. Many now assume that hardware is no longer a bottleneck. Yet the ongoing debate between proponents of rotary and linear actuators shows that hardware choices remain critical to the industry’s future.

Full report : China’s robotics ecosystem excels at rotary actuators, but its lag in high-precision planetary roller screws still limits progress toward industrial-grade humanoids.