Unitree PMSM
Unitree PMSM is a family of integrated joint actuators based on permanent magnet synchronous motors. In Unitree's public materials, the actuator is described as a low-inertia, high-speed internal rotor PMSM — a design characterized by low rotational inertia, high response dynamics, and improved heat dissipation.
The solution serves as the primary joint actuator in Unitree robots, particularly in the H1, H1-2, H2, and G1 humanoid series. Depending on the specific joint, gear ratio, and robot variant, the actuator delivers varying torque outputs — from approximately 90 N·m in the largest G1 joints, to 120 N·m in selected arm joints, and up to 360 N·m in certain leg joints of the H1/H1-2/H2 models.
Publicly confirmed characteristics of this actuator class include high integration, crossed roller bearings in the joint units, local air cooling, temperature sensors, and absolute or dual encoders depending on the platform. The Unitree developer ecosystem also provides software access to motion control and integration with SDK2 / DDS / ROS2.
Classification
PMSM Actuator · serves as: Joint Actuation, Locomotion Drive, Manipulator Drive. · compatible with: Humanoid, Legged Robot.
Which group Unitree PMSM belongs to and how it is built
A subcategory covering joint actuators — integrated drive units combining a motor, gearbox, encoder, and control electronics in a single module, used in the joints of robot limbs and torsos.
Component type covering actuators that use a Permanent Magnet Synchronous Motor — high-dynamics motors with low inertia and good heat dissipation, used in humanoid and legged robots.
A design class encompassing electric drives with an internal rotor — a low-inertia, high-speed configuration used in integrated joint actuators of humanoid robots.
Technical specification
Basic physical properties of Unitree PMSM — dimensions, weight and materials
Relations
Other hardware parts related to Unitree PMSM
Software
The drive operates within the Unitree SDK / Motor SDK / SDK2 ecosystem. Publicly confirmed developer interfaces include motion control APIs and a ROS2-compatible communication layer.