title: Configuration optimization and experimental accuracy evaluation of a bone-attached, parallel robot for skull surgery.
abstract: OBJECTIVE
  Minimally invasive cochlear implantation is a novel surgical technique which requires highly accurate guidance of a drilling tool along a trajectory from the mastoid surface toward the basal turn of the cochlea. The authors propose a passive, reconfigurable, parallel robot which can be directly attached to bone anchors implanted in a patient's skull, avoiding the need for surgical tracking systems. Prior to clinical trials, methods are necessary to patient specifically optimize the configuration of the mechanism with respect to accuracy and stability. Furthermore, the achievable accuracy has to be determined experimentally.
  
  
  METHODS
  A comprehensive error model of the proposed mechanism is established, taking into account all relevant error sources identified in previous studies. Two optimization criteria to exploit the given task redundancy and reconfigurability of the passive robot are derived from the model. The achievable accuracy of the optimized robot configurations is first estimated with the help of a Monte Carlo simulation approach and finally evaluated in drilling experiments using synthetic temporal bone specimen.
  
  
  RESULTS
  Experimental results demonstrate that the bone-attached mechanism exhibits a mean targeting accuracy of [Formula: see text] mm under realistic conditions. A systematic targeting error is observed, which indicates that accurate identification of the passive robot's kinematic parameters could further reduce deviations from planned drill trajectories.
  
  
  CONCLUSIONS
  The accuracy of the proposed mechanism demonstrates its suitability for minimally invasive cochlear implantation. Future work will focus on further evaluation experiments on temporal bone specimen.
authors.affiliation: Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany. jan-philipp.kobler@imes.uni-hannover.de.
authors.forename: Jan-Philipp
authors.initials: JP
authors.lastname: Kobler
authors.affiliation: Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Nuelle
authors.affiliation: Hannover Medical School, 30625 , Hanover, Germany. lexow.jakob@mh-hannover.de.
authors.forename: G Jakob
authors.initials: GJ
authors.lastname: Lexow
authors.affiliation: Hannover Medical School, 30625 , Hanover, Germany.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Rau
authors.affiliation: Hannover Medical School, 30625 , Hanover, Germany.
authors.forename: Omid
authors.initials: O
authors.lastname: Majdani
authors.affiliation: Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany.
authors.forename: Lueder A
authors.initials: LA
authors.lastname: Kahrs
authors.affiliation: Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kotlarski
authors.affiliation: Institute of Mechatronic Systems, Leibniz Universität Hannover, 30167 , Hanover, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Ortmaier
mesh_terms: D001696:Biomechanical Phenomena; D003051:Cochlea / Q000601:surgery*; D019929:Cochlear Implantation / Q000379:methods*; D006801:Humans; D008416:Mastoid / Q000601:surgery*; D065287:Robotic Surgical Procedures / Q000379:methods*; D053441:Suture Anchors
keywords: Accuracy evaluation; Cochlear implant surgery; Minimally invasive surgery; Parallel robot; Surgical robotics