Automating the Leksell Frame Adjustor: Incorporating Phi and Theta Movement to Achieve 5 Degrees of Freedom and Trajectory Planning of the Device

Abstract

The Leksell Frame is a device used in stereotactic surgery, commonly for Deep Brain Surgery (DBS). The device requires manual adjustments and soft tapping using a screw to set the target location on the brain. It is prone to human error, limiting its precision and efficiency. The aim of the project is to modernize the Leksell Frame Adjuster (LFA) by automating its movements to achieve full freedom of motion with five degrees of freedom. A new design-based solution with an added circular frame resembling a lazy susan serves as an alternative to the stereotactic arc of the original Leksell Frame, offering the same capabilities but with better efficiency. The system utilizes matrix transformations, a closed-loop Proportional-Integral-Derivative (PID) control, and motors to create precise adjustments in a spherical coordinate system. The Matrix transformations effectively simulate rotational transformations in the phi (φ) and theta (𝜃 ) directions of the circular frame. During testing, the precision of randomly generated coordinates was within the ideal error range of ±2mm. There were some challenges in the motor performance using PID control. The tuning of the PID revealed significant oscillations and instability and further optimization for a stable and responsive motor control will be required in the future steps. Other future steps include scaling testing to more realistic ranges, incorporating real-time feedback mechanisms, and physical prototyping. Overall, the simulations demonstrate the promise in automating the LFA, reducing surgery time and increasing accuracy.

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