The RMD-X8 (now designated X8-25 in V2 nomenclature) is a popular modular actuator from MyActuator with a 9:1 planetary gearbox. Delivers 25 Nm peak torque and is available with CAN BUS or RS-485 interface. Used in legged robots, manipulators, and exoskeletons.
The actuator integrates a BLDC motor, gearbox, and encoder in a compact housing weighing ~700 g. Supports position, velocity, and torque control modes. Popular in research applications due to its open communication protocol.

Rotary Actuator · serves as: Joint Actuation, Manipulator Drive.
Which group RMD-X8 (X8-25) 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.
A rotary actuator is a component responsible for generating controlled rotational motion. It can be implemented as an electromechanical, pneumatic, or hydraulic module, depending on the application. In robotics, rotary actuators are used in joints, positioning mechanisms, manipulator drives, and automation equipment where angular motion is required.