World’s Smallest Frameless Torque Motor: MARHE’s HummingDrive Delivers 12 mNm in a 3.5 g Package

On July 19 at WAIC, MARHE announced the third‑generation HummingDrive™ series of micro frameless torque motors, the smallest of their kind globally. The launch follows two years of intensive R&D in collaboration with leading humanoid‑robot manufacturers and builds on a doctoral team’s long‑term expertise in electromagnetics.

The motors cover outer diameters from 9.9 mm to 20 mm, with a minimum weight of 3.5 g and a maximum peak torque of 12.33 mNm. Their core employs ultra‑high‑performance rare‑earth permanent‑magnet material whose residual flux density (Br) reaches 1.6 T, tightly coupled with a Halbach magnetic topology. This synergy pushes the air‑gap flux density near the material’s physical limit, delivering a marked increase in torque density per unit volume.

Realising this performance required four tightly integrated manufacturing steps: (1) precision forming of ultra‑thin magnet tiles, (2) multi‑directional synchronous magnetisation of an extremely small inner bore, (3) micron‑level automated assembly of mutually repulsive magnet tiles, and (4) reinforcement of the rotor with an ultra‑thin carbon‑fiber sleeve. Each step creates a substantial engineering barrier that safeguards the design’s advantages.

The authors contend that every breakthrough in drive‑unit design redefines both the technical capabilities and commercial boundaries of motors. By directly addressing the demand for “smaller volume, higher torque, stronger performance,” the HummingDrive series supplies a lightweight, efficient, and stable power source for applications such as dexterous hands and grippers in humanoid robots, surgical robots, endoscopic drives, precision injection systems, and rehabilitation exoskeletons, thereby helping physical‑AI innovations become practical.