A Highly Compact, Multi-Material, Fluid Powered Actuation System for MRI-Guided Surgical Intervention
AUTHORS
ABSTRACT
This paper presents an inherently safe, compact, 3D-printed, fluid-powered stepper actuation system enabling surgical precision within the demanding and confined space of a magnetic resonance imaging (MRI) scanner. The intense magnetic field and limited workspace of an MRI excludes the use of traditional, ferromagnetic robotics. Additionally, scanner image quality is sensitive to interference, creating a strict constraint on the electromagnetic and ferromagnetic signature of the actuator. While non-ferromagnetic, fluid powered actuators exist, they are often bulky and difficult to control. Using high resolution, material jetting technology, we’re able to 3D print small, standalone multi-material designs with variable rigidity. Leveraging these advances in additive manufacturing technology, we have developed a modular set of miniature flexible fluidic actuators (FFAs). These actuators are capable of translating, rotating, and gripping a slender rod and are inherently safe to valve, control, or pressure faults, due to the stepping sequence. Using a specific clinical application as a use case, we assembled these components into a highly compact needle steering system for MRI-guided neurosurgery. This two-degree-of-freedom actuation system is driven pneumatically, taking advantage of sterile, hospital instrument air and is electromagnetically transparent to the MRI scanner. In addition to detailing the actuator system design, this paper also demonstrates a robust, nonlinear control strategy for precision sub-step motion control. This paper reports the actuator system’s operating pressure and bandwidth, translational and rotational accuracy, and maximum force and torque capabilities.
Tags: Conference Papers 2023