Tema da Tese: Development of a robotic system to assist neurosurgeons in minimally invasive stereotactic procedures.

Autor: Carlos André de Oliveira Faria

Programa Doutoral: Programa Doutoral em Engenharia Biomédica

Orientadores: Estela Bicho; Wolfram Erlhagen

Data: 04/11/2020

Abstract:  Technology is often the answer to most of our problems. Robots revolutionized the industry and are finding their way into more complex and critical applications, including surgery. The stereotactic method was developed to reach intracranial brain structures without direct visualization and through a minimally invasive approach, based on a coordinate system. Due to the format of stereotactic and functional surgeries, the suitability of robots as a neurosurgeon’s assistants is apparent. Robots are accurate, repeatable, and configurable agents often assigned to tool guidance. Despite these advantages, only a handful of surgical robots reached the market. Current surgical robotic systems in practice exhibit high up-front costs with slow investment return, a limitation in part caused by the difficulty in transferring technologies from the research center into the surgical room. In this thesis, we examine the principal neurosurgical robotic systems to identify the common denominators and the most requested features, replacement of the stereotactic frame, affordable access to flexible, interactive, and accurate robotic solutions. We propose two solutions to address these subjects. First, we adapted an industrial 6 DoF manipulator with a monolithic control system, as a proof-of-concept and research tool. The second solution consists of a modular control architecture, built on top of a well-established component and communication model, with deterministic behavior and supporting hard-real-time constraints, tested in a 7 DoF manipulator. At the core of the modular architecture, is a novel analytic inverse kinematics method for serial redundant manipulators capable of uniquely solving the nullspace, avoiding singularities, and joint limits. This method provides the manipulator with the flexibility to adapt to the available workspace, which is shared by the surgery team and by other equipment. The proposed architecture also includes a list of interconnected controllers and supervisor components to perform the different surgical tasks. We also developed and validated a new algorithm to determine the real kinematic model parameters of manipulators, parameters that may differ from nominal values. We tested the system’s application accuracy in vitro and registered a mean error of 0.567 mm, and a maximum error of 1.094 mm. The real advantage of the proposed solution lies in its performance, flexibility to integrate new modules, and in the capacity to upgrade individual components without the need to overhaul the entire solution or escalate the costs.

Keywords: High-level Control Systems, Robotics, Stereotactic Surgery.