Motion Analysis of Robot Arm With Movement Restriction

Abstract

Medical robots are increasingly being used to assist surgeons during procedures requiring precision. As reported in the literature, surgeons have been opting for minimally invasive surgery, as it reduces patient complications, overall patient recovery time, and hospital time for the patient. Robotic manipulators can be used to overcome natural limitations related to vision and human dexterity, and allow surgeons to transcend these limitations without having to sacrifice improvement in patient outcome. A desirable attribute of surgical robots is maneuverability similar to the human arm. The KUKA DLR Lightweight Robot Arm (LWR), with seven degrees of freedom, retains many of these human-like dexterity traits. Due to the KUKA robot arms maneuverability and flexibility, it is well-suited for intricate tasks based upon motion analyses and modeling of the compliance to path trajectory in addition to the overall smoothness of the path. This robot may be further programmed to be effective and precise for surgical applications. In the studies reported here, a unique Rapidly exploring Randomized Tree (RRT) based path-planning algorithm is developed and this algorithm is used to generate path plans between an initial state and a goal state for simulated models of robotic manipulator arms. Along with constraints, the RRT algorithm has been implemented to find paths for the chosen kinematic or dynamic robotic manipulator arm. Similar techniques are to be used to analyze the KUKA LWR IV+ system. Motion analyses have been carried out with consideration of motion trajectories and all possible locations of the end effector with unique constraints applied to the system. In these simulations, the Denavit-Hartenberg parameters were recorded, with special attention to movement restrictions. The results of the RRT paths generation, analysis of the manipulator arm trajectories, and simulations allow one to better determine the location of the end-effector at any given point in time and location. From this foundation, the generation of path-planning restrictions for the KUKA robots path programming is expected to take into account surgically restricted dangerous or undesirable zones. In future work, the trajectories of the KUKA robot and other manipulator arms are to be compared with the data available in the literature. This work holds promising implications for the improved use of such robot systems in surgical applications. For example, precise pre-programmed robotic movements are expected to be particularly helpful for surgeries in tight, anatomically restricted sites, with adjacent delicate tissues. Ultimately, it is expected that this type of novel robotic application will greatly aid surgeons in improving the precision and safety of surgical procedures, by reducing potential complications and minimizing potential nicks and tears, and working towards giving the surgeons the same ease that they have with traditional surgery.