Final Design

Figure A: CAD model of final design

Design Solution

To meet the requirements set by the CFMRI sponsors, the existing positioning system was improved through the addition of a scanner room controller box that communicates with the existing LabVIEW system via fiber optic connection to an Arduino UNO microcontroller. This connection allows for the position of the tooling plate to be relayed to the LabVIEW interface for position control purposes. The MRI room controller has four buttons: “SET LANDMARK’, “GO TO ISOCENTRE”, “GO TO LANDMARK”, & “MTR ON/OFF”. These allow the operator to move the sample in the correct imaging position, or isocentre, while standing next to the sample to ensure it clears any obstructions during its movement down into the bore of the MRI machine. A mobile table stand for the system has also been implemented so that the positioning system can be integrated into scanner room for use on the 7T MRI machine. The table has been equipped with the ability to be adjusted in the vertical direction to accommodate various tooling sizes as well as leveling capabilities. An aluminum lead screw and Delrin lead nut have been fitted to the table to allow for vertical adjustment. It is operated by turning a rotating wheel attached to the lead screw, effectively raising and lowering the table. The system has also been equipped with four leveling casters that allow for easy moving and leveling of the system. shelves have been added to the midsection of the table for storage capabilities.

System Performance

the lead screw required a torque of 1.2 N·m (0.9 ft·lbf) when the table was unloaded. When the table was loaded with 13.5 kg (30 pounds), the lead screw required a torque of 2.3 N·m (1.7 ft·lbf). The controller interfaces directly to the LabVIEW controller and so as long as the electronics are properly connected the controller performs to the same specs as the existing control system. Figure B shows the result of a test performed on the 7T MRI machine and shows that samples are easily adjusted and results are repeatable. The gray line in the center of the image indicates the ISOCENTRE position inside of the 7T MRI machine.