Actuators & Motors
Actuators and motors are the muscles of a humanoid robot: rotary or linear drive units that typically pair a brushless DC (BLDC) or frameless motor with a precision reduction stage (harmonic, planetary, or cycloidal gearing), an encoder, and driver electronics to produce controlled torque at each joint. Industry analysts frequently cite actuators as the single largest cost driver in a humanoid robot's bill of materials, and their torque density, backlash, and thermal performance directly determine a robot's payload, speed, and endurance.
Manufacturers
6 companies
ROBOTIS is a South Korean robotics company best known for its DYNAMIXEL line of all-in-one smart actuators, which integrate a DC/BLDC motor, reduction gearhead, controller, driver, and network interface into a single modular unit. ROBOTIS built its own full-size humanoid research platform, THORMANG, powered by DYNAMIXEL-Pro actuators, which competed in the 2015 DARPA Robotics Challenge. Its newer DYNAMIXEL-Y and DYNAMIXEL-P series are marketed specifically for humanoid robots and "Physical AI" applications.
Harmonic Drive Systems Inc., founded in Tokyo in 1970, invented and commercializes strain-wave ("harmonic drive") gearing, a near-zero-backlash reduction technology that is an industry standard for compact, high-precision robot joints. Its US subsidiary, Harmonic Drive LLC, manufactures precision servo actuators, gearheads, and gear component sets built on the same technology. This class of actuator is used across humanoid and legged-robot joints industry-wide because it delivers a high single-stage reduction ratio (roughly 50:1 to 160:1) in an axially short, lightweight package. Humanoid-specific sourcing for any single named robot program is not independently confirmed; this reflects general industry adoption of strain-wave actuators of this type.
CubeMars is a Chinese manufacturer of compact, integrated robotic actuators and frameless torque motors, operating as a brand under Sanrui Intelligent. Its AK-series actuators combine a BLDC motor, planetary or hollow-cup reduction stage, and dual encoders in a single housing, and have become popular among humanoid, quadruped, and exoskeleton developers for their compact form factor and low backlash (rated within 9 arc-minutes). In April 2025 CubeMars won the "2025 Outstanding Supplier for Humanoid Robots" award at the 2nd China Conference on Humanoid Robotics and Embodied Intelligence.
Maxon is a Swiss precision motor manufacturer known for high-efficiency brushless DC and coreless DC motors, gearheads, and frameless motor/encoder kits used across robotics, medical devices, and aerospace. Rather than selling complete integrated joint actuators, Maxon typically supplies the motor and gearhead components that robot builders combine into custom actuator housings. Ninety-three Maxon brushless motors power the University of Tokyo's 160-"muscle" tendon-driven humanoid research robot Kenshiro, and Maxon markets its EC frameless DT motor family directly for humanoid and exoskeleton joints.
Kollmorgen is a US motion-control company, now part of Regal Rexnord, that manufactures frameless servo/torque motors, direct-drive motors, and servo drives used to build compact, high-torque-density robot joints. Its TBM2G frameless motor series is designed to be embedded directly into a robot's mechanical structure to minimize joint weight and inertia, and the company maintains a dedicated humanoid-robotics solutions line targeting logistics, manufacturing, and service-robot developers. Robotics integrators such as RobCo and HEBI Robotics have used TBM2G motors in their robot joints.
MyActuator, operated by Suzhou Micro Actuator Technology Co., Ltd. (established 2020), manufactures compact brushless DC servo actuators for robot joints, combining a BLDC motor, planetary reduction stage, dual encoders, and CAN/EtherCAT/RS485 communication in a single integrated module. Its RMD-X series is widely adopted by university and open-source humanoid and legged-robot projects; for example, the open-source AGILOped humanoid robot uses MyActuator RMD-X6-40 actuators with two-stage planetary gearing for all of its joints.