Kepler’s K2 “Bumblebee” humanoid robot also adopts 12 self-developed planetary roller screw actuators paired with rotary actuators. It can last up to 8 hours on a single charge and lift 30 kg of weight with ease. Thanks to its proprietary core technology, the base version costs only $30,000.
In China, Unitree’s humanoid robots R1 and G1 use high-precision planetary roller screws in their leg actuators. UBTech’s Walker X and Zhiyuan robots also incorporate planetary roller screws, supplied by Yuhua Precision, a subsidiary of Best. Rumors suggest that the Unitree robot showcased at the Spring Festival Gala used planetary roller screws provided by Changsheng Bearings.
Planetary roller screws operate through line contact rolling friction, avoiding significant material wear. Their lifespan is 10 times that of ball screws. They also possess a degree of self-locking, sharing part of the load and reducing the actuator’s power consumption.
That is their mystery.