In discussions about robotic joint actuator modules, the motor, gearbox, encoder, brake, and driver usually receive the most attention, while the braking dissipation module is often underestimated. In real engineering projects, many 48V joint systems operate normally during no-load commissioning. However, once they enter conditions involving large inertia, rapid acceleration and deceleration, gravity-axis lowering, or frequent backdriving, issues such as DC bus overvoltage, driver alarms, unexpected shutdowns, and even thermal failures of power devices begin to appear.

The selection of robot joint actuators for humanoid robots is essentially a precise matching of functional requirements, performance trade-offs, and cost control. Among today’s mainstream solutions, harmonic joint actuators are typically prioritized for upper limbs, while planetary joint actuators are favored for lower limbs. This combination is not accidental, but rather the optimal solution derived from the distinct motion characteristics of the upper and lower body. The differentiated approaches taken by companies such as Unitree and UBTECH also stem from specific considerations tied to their product positioning.