ISBN 978-3-86853-797-0

978-3-86853-797-0, Reihe Robotik und Automation

Ulrich Hagn
The Aspect of Versatility in the Design of a Lightweight Robot for Surgical Applications

317 Seiten, Dissertation Universität Hannover (2010), Softcover, B5

Zusammenfassung / Abstract

This work presents the design and the prototypical implementation of a versatile lightweight robot for surgical applications the MIRO.

With respect to the design of a surgical robot arm, two antipodal approaches define the range of design strategies. One is to focus on a single application with a specialised system. The second approach focuses on a versatile system for a range of applications. This work follows the second approach in order to enable rapid prototyping of new surgical techniques, to cover more than one step during an operation by the robotic system, and to broaden the foundation for the use of robotic technologies in different surgical applications. Therefore, the goal of this thesis is to prove the feasibility of designing a surgical robot with extended versatility.

Based on a survey of the current state of surgical robotics, this work identifies central design aspects for medical robots. The applied development method avoids the limitation of the desired versatility in early development phases: First, a generic design of the robot arm is developed, based on design aspects which are supposed to generally enhance the use of the system in operating rooms. Second, concrete performance requirements from a range of surgical applications are derived for the MIRO and the generic design is scaled and optimised accordingly.

The MIRO robot weighs 9.8 kg with a maximum payload of 3 kg. The seven DoF serial kinematics intentionally resembles those of the human arm in order to increase the familiarity of non-technical users with the robot arm. Furthermore, the joint redundancy allows for collision avoidance by null-space motion. The low weight of the MIRO targets different setup options, like mounting of one or multiple arms at an operating table or a ceiling boom. Setups with multiple arms demand for compact dimensions of the robot, which are achieved by coupling joints. Wrist and end effector design enable the use of endoscopic and conventional instruments. Integrated joint torque sensors are applied to measure external interaction forces, to enable hands-on robot approaches, compensate for elasticities, or to detect collisions.

The MIRO robot is applied and evaluated in prototypical surgical applications at the DLR. In a navigated robot-assisted biopsy application, a precursor of the robot was combined with a surgical navigation system and combines hands-on with autonomous procedural steps. In the ASTMA project, the MIRO robot guides an ultrasound transducer in order to explore the left internal thoracic artery. In tests for osteotomy tasks in orthopaedic surgery, the MIRO robot proves robustness against the vibrations of an oscillating saw. The position accuracy and repeatability of the MIRO for laser-osteotomy tasks was identified with 0.5 mm and 0.2 mm, respectively. In the MiroSurge system, three MIRO arms are integrated as telemanipulators in a telerobotic minimally invasive surgery setup.

In conclusion, this thesis proves the feasibility of designing a robot with extended versatility, optimised for the use in operating rooms, and applicable in a comprehensive, but not unlimited, range of surgical applications.