About Model T

The Model T is the initial released design of the Yale OpenHand Project, based on the original SDM Hand. It consists of four underactuated fingers with compliant flexure joints, driven by a single actuator through a pulley tree differential. During grasp acquisition, each finger will continue to move until the links make contact with the object, reducing the need for sensors or feedback control. The fabrication process for the fingers is the basis for all the designs made available through the Yale OpenHand Project.

Variations of the original SDM hand have been featured on aerial grasping platforms and iRobot batting practice.

R. R. Ma, L. U. Odhner, A. M. Dollar
"A Modular, Open-Source 3D Printed Underactuated Hand," Proceedings of the 2013 IEEE International Conference on Robotics and Automation (ICRA), Karlsruhe, Germany, May 6-10, 2013.

A. M. Dollar, R. D. Howe,"The Highly Adaptive SDM Hand: Design and Performance Evaluation," International Journal of Robotics Research, 29 (5), 2010, pp. 585-97

Design Options





  • Actuator: Dynamixel XM430/MX-64
  • Base Height: 95mm
  • Base Diameter: 100mm
  • Weight: 490g
  • Holding Force: 10-13N

Capabilities (Video)



  • Revisions 2.0.0 and 1.0.0 [Github]
  • Revision 1.0.0 (02/17/2015) [.zip]
  • Revision 0.5.2 (11/14/2013) [.zip]
  • Revision 0.5.0 (06/02/2013) [.zip]
  • Revision 0.4.1 (04/02/2013) [.zip]