Description
Current MR-safe medical robots intended for cancer biopsies often lack precise position feedback. This limitation can lead to prolonged procedures and difficulties in accurately reaching the correct position to retrieve the needle-core samples of the suspected cancer cells. This project intends to address this issue by implementing a way to accurately estimate the robots pose within the MRI machine. The Mamri is a 6DOF robotic arm operated using pneumatic stepper motors located at each joint. Currently there is no way to measure if the stepper motors skipped steps and this can lead to discrepancies between the indented position and the actual position of the robot arm. It is intended to combine two separate techniques for robotic pose estimation.
Fiducial markers
Firstly, it utilizes fiducial markers embedded into the robot in predefined positions and arrangements. These markers serve as visual reference points that are visible in the final MR-image. By retrieving the fiducial markers positions from the MR-image the current robot pose can be estimated by determining the location of each joint and from there determining what the specific joint angles are.
Fiber optic joint encoders
To complement the pose estimation using the fiducial markers it is intended to outfit each stepper motor with fiber optic encoders. Unlike traditional electronic encoders, fiber optic encoders are immune to electromagnetic interference, making them MR-safe. They are intended to count the steps taken by the stepper motors of each joint and in combination with the fiducal markers provide a precise estimate of the robots orientation.
Goals
This research intends to greatly improve the accuracy of biopsy robots and aims to greatly reduce the procedure time for a cancer biopsy in an MRI environment using a medical robot.
