Many robotic and motion control applications demand precision rotary transmissions that can deliver high torque in compact assemblies. Planetary, or epicyclic gear drives and harmonic drives are commonly used, due to their many advantages. However, they also have drawbacks ranging from complex and higher cost manufacturing, to the potential for excessive backlash, leading to gear box wear, noise, and vibration.

Gearbox backlash depends on several qualitative factors, including manufacturing precision of the gears, bearing and housing precision, metal hardness, and precision of assembly. However, a large portion of the backlash depends on the design arrangement, dimensioning and geometry of the gearbox. A recent market survey on today’s planetary gearboxes revealed that most of the existing planetary transmissions have the same gearbox architecture.

Technology Overview

Northeastern researchers have developed a low-cost, low-backlash advanced planetary actuator called the Gear Bearing Drive, or GBD. It utilizes a unique two stage planetary gear arrangement that allows a high reduction ratio, while maintaining a compact form factor. Traditional ball bearings and carriers are not used, replaced instead, by roller bearing surfaces to provide both axial and radial support to the mechanism. These features, combined with the low number of parts required for this gearbox, increase the ease of manufacturing when compared to the traditional gearbox design.


  • Novel design enables low-backlash (the key cost indicator for planetary transmissions)
  • Reduction of parts provides lower cost and greater ease of manufacturing
  • Enables high torque while maintaining a compact form factor
  • Compact assembly allows for use in wide range of applications


  • Robotic manipulation (joints of robotic arm)
  • Precision manufacturing
  • Multi-axis servo systems
  • Electric car industry (power train system)


  • License
  • Development Partn

Intellectual Property status

Provisional Application No. 61/804,256

License status

Available for license

Patent Information:
For Information, Contact:
Dormant Physical
Northeastern University
Elias Brassitos
Constantinos Mavroidis (bei)
Brian Weinberg
Qingchao Kong