Bio-inspired Robotics for Minimal-Invasive Surgery

At the BIROMED-Lab, we work on developing novel technology to advance robot-assisted medical interventions. I will provide a short overview on our current research challenges with a focus on robot-assisted, minimally-invasive surgery. Minimal-invasive surgery results in faster patient recovery and using robotic tools allows to further enhance surgery outcome. Such robot-assisted minimal-invasive surgery is typically realized by replacing the direct manual guidance of instruments with telemanipulated or robot-guided instruments. For example, hand tremor can be filtered or the surgeons’ motions can be scaled. Up to today, the concepts for robots in surgery were mostly built on serial mechanisms that were composed by rigid links with dedicated joints in between. Rigid serial robots are well-suited for repetitive tasks in a large workspace, but do not perform well in terms of end-effector positioning accuracy, since errors accumulate along their length. However, high accuracy is required in a rather small workspace in the vicinity of the surgical site inside the patient. For accurate movements of a scalpel or pen, humans tend to support their wrist or elbow locally and apply parallel actuation of the tool through multiple fingers. Mimicking this behavior we have developed a small parallel robotic device that fitted inside the knee joint, which could fix itself close to the target tissue to provide stability for laser-based bone ablation with an accuracy of 0.2 mm. Small structures that fix close to the target tissue at the surgical site (e.g., inside the patient) allow to compensate disturbances and to reduce the size of the robot’s structure in the operating room. As a second example, we have drawn inspiration from the human finger for surgical robot design. Fingers can be positioned precisely because of closed-loop position feedback, they can safely interact with the environment thanks to their compliance, and they can provide force feedback. These advantages can be transferred to surgical robots by replicating the structurally intelligent actuation of human fingers. We designed an articulated robotic endoscope with joints driven by antagonistic tendons based on series elastic actuation (SEA). Due to closed-loop, low-level force control, interaction forces with the environment from actuated endoscope movements can directly be limited. Applications of such smart SEA-endoscopes are interesting in particular for automated tracking of structures, while ensuring safety for the surrounding tissues.