Smart Control of MR Safe Pneumatic Stepper Motors

MRI-based invasive surgery requires that the equipment being used during that time is MR safe (or conditional) and does not interfere with the MRI scan. One example application is a biopsy of lesions in the breast that sometimes can only be detected on MRI. There are limitations in manual biopsy procedures: the space inside the MRI scanner is not adequate for the radiologist to insert the needle inside the MRI scanner under visual guidance. While performing the procedure blindly outside the scanner may result in a failed biopsy. This can be overcome using a robotic system inside the scanner to increase accuracy and reduce the total time for the procedure.

The Stormram series and the latest version Sunram 5 are MR-safe robotic systems for breast biopsy, these kinds of robots use pneumatic stepper motors which are made of MR-safe material and driven by feed-forward control algorithms. There are currently no sensors in the robots that make calibration difficult and detection of missed steps impossible.

The main objective of this thesis is to create a smart control of the pneumatic stepper motor for next-generation Sunram and related robotic systems. Features like automatic calibration, position feedback system, easy integration, high speed, and high accuracy would enable the robot to complete the procedure effectively and efficiently in a shorter period.

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