title: Design, Fabrication, and Testing of a Needle-Sized Wrist for Surgical Instruments.
abstract: This paper presents a miniature wrist that can be integrated into needle-sized surgical instruments. The wrist consists of a nitinol tube with asymmetric cutouts that is actuated by a single tendon to provide high distal curvature. We derive and experimentally validate kinematic and static models for the wrist and describe several prototype wrists, illustrating the straightforward fabrication and scalability of the design. We experimentally investigate fatigue life, the concept of tip-first bending, and practical use of the wrist with a concentric tube robot in an endonasal surgical scenario.
authors.affiliation: Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37212 e-mail:  philip.j.swaney@vanderbilt.edu.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Swaney
authors.affiliation: Department of Mechanical Engineering, Harvard University, Cambridge, MA 02138.
authors.forename: Peter A
authors.initials: PA
authors.lastname: York
authors.affiliation: Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37212.
authors.forename: Hunter B
authors.initials: HB
authors.lastname: Gilbert
authors.affiliation: Associate Professor Center of Mechatronics, Leibniz Universität Hannover, Hannover 30167, Germany.
authors.forename: Jessica
authors.initials: J
authors.lastname: Burgner-Kahrs
authors.affiliation: Associate Professor Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37212 e-mail:  robert.webster@vanderbilt.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Webster