Development of an Interface for Integrating Off-the-Shelf Laparoscopic Instruments into an End-Effector of a Robotic System for Collaborative Surgeries

Kurzfassung

This thesis presents the design, development, and validation of a mechatronic interface that integrates off-the-shelf laparoscopic instruments into an existing robotic arm (DLR MIRO) to enable collaborative (surgeon-operates robot collaboration) and teleoperated minimally invasive surgery. The core aim was to bridge conventional hands-on laparoscopy and full telemanipulation by providing an adapter that allows for teleoperation of at least three degrees of freedom (DoFs) per tool (thrust along the shaft, roll about the shaft axis, and tool tip jaw actuation), while the additional actuation requirements of linear staplers were accommodated. Building on prior prototypes, the end-effector concept (LinAx 2.0) was refined and extended, and a Universal Teleoperative Tool Adapter (Univ TTA) with an adaptable gripper and force estimation capabilities was developed. The mechanical system was modularized into four subsystems: a four-stage prismatic thrust actuator achieving 400 mm stroke was implemented, a roll actuation module with improved unrestricted rotation was realized, a universal tool handle actuation, and a teleoperated stapling cover (StapCov) was provided. Further, control concepts for position-controlled thrust and roll as well as force-based tool tip actuation were established. Validation protocols were defined and executed, including static compliance, uni- and bidirectional accuracy and repeatability tests, grasping force estimation evaluation, stapling reliability trials (n=30 cycles), and usability tests for switching between surgical modes. Results showed that the extended LinAx achieved the required stroke while the total system mass (including Univ TTA and stapler module) was kept at 2.55 kg, below the payload limit of the MIRO, although increased internal friction and some degradation in dynamic precision were observed. Static compliance was found to be comparable to earlier iterations. Positioning repeatability was observed to be satisfactory (0.29 mm– 0.31 mm), with accuracy decreasing at large extensions due to mechanical play. Stapling actuation was proven reliable with repeatability below ±1 mm. Mode switching was enabled by the Univ TTA in approximately 25 s. Grasping force estimation via motor current was limited in accuracy, indicating that improved sensing is required. In summary, by the developed interface, the base was built to enable flexible, hybrid workflows between hands-on and teleoperated laparoscopic interventions for the full range of required instruments