Structural design of a microsurgery-specific haptic device: neuroArmPLUSHD prototype

Abstract A microsurgery-specific haptic interface with articulated structure, possessing 3 active, 4 passive and 3 supplementary degrees of freedom (DOFs), was designed and developed. The system includes a 3-DOF active serial linkage design, mimicking the human upper extremity. It is combined with a microsurgery-specific end-effector, comprised of a 3-DOF passive gimbal mechanism and a 1-DOF passive exchangeable surgical toolset. The spherical gimbal workspace twinned with the larger linkage arm workspace allow accurate and delicate movements to maneuver the surgical tool in narrow corridors, corresponding to conventional surgery. The structural design of the device is based on kinematic performance measures aimed to enhance ergonomics and mitigate training limitations of novice end-users. A supplementary 3-DOF adjustable base further improved ergonomics for end-users of different sizes. Force feedback was provided to improve safety, i.e. avoidance of force errors in execution of surgical tasks. This haptic interface provides high positional and output force resolution (0.92–1.46 mm in Cartesian coordinate system and 0.2 N, respectively), wide range of allowable force (up to 15 N), high global manipulability (0.77), global isotropy (0.68) and stiffness (2.3 N/mm). The work, indeed, introduces a novel kinematic performance index, Dexterous Conditioning Index (DCI), based on the volume of dexterous workspace, correlating to ease of use and decreased singularity. Accordingly, the proposed haptic device demonstrates a high level of accuracy, haptic feedback, dexterous workspace, and performance, ideal for implementation in robot-assisted microsurgery.