New concept for the instrument of SOFIE

The goal of this traineeship was to see if improvements could be made on the instrument of SOFIE (Surgeon’s Operating Force-feedback Interface Eindhoven) with regards to the stiffness, manufacturing costs, life time etc. The instrument tip contains four degrees of freedom, pitch, roll, pivot and close, which can be seen in figure 2. Three concepts on driving the first two of these DOF’s have been generated, one of which has been elaborated to a more detailed level. This concept is described in section 2 and will be the main subject of this report, the other two will be described more briefly in the appendices. In section 2.1 and 2.2, the kinematics of respectively pitch and roll in the new concept will be explained. To quantify improvements, the stiffness of the current design has been compared to the new design in section 2.3. A new drivebox layout is proposed in section 2.4 and conclusions and recommendations regarding this design can be found in section 2.5. Improvements in the main concept concern only pitch and roll. The calculated improvement in stiffness of the pitch DOF actuation is a factor 3, while maintaining the same stiffness in roll actuation. Also, by reducing the number of gears in the roll DOF, the backlash is reduced by a factor 2. The actuation system for the remaining DOF’s (pivot and close) still needs to be redesigned.