This article provides an in-depth comparison between Direct Drive (DD) motors and harmonic rotary actuators, covering their transmission principles, advantages and disadvantages, and typical application fields.

Harmonic rotary actuators (typically integrated systems consisting of a harmonic drive reducer, frameless torque motor, encoder, and optional brake) are regarded as key components in medical equipment. The core reason is that they simultaneously meet the most stringent medical requirements for precision, compact size, safety, and controllability. The following explanation is structured from three perspectives: technical characteristics, application scenarios, and medical value.

Humanoid robots are rapidly transforming industries ranging from manufacturing and healthcare to logistics and public services. At the heart of every robot's movement is the actuator—the component responsible for converting electrical energy into precise mechanical motion. Among the different actuator technologies available today, harmonic rotary actuators have become the preferred solution for humanoid robots due to their compact size, high torque density, exceptional positioning accuracy, and reliable performance.

When selecting a motion control solution, understanding the strengths and limitations of a harmonic rotary actuator is essential. While these actuators are widely recognized for their exceptional precision and compact design, they also have inherent limitations that make them unsuitable for certain heavy-duty applications. This guide provides a comprehensive overview of the advantages and disadvantages of harmonic actuators, helping engineers choose the right transmission solution based on their specific application requirements.