Leg Support

Student group project, 2016

This project was based around a newly developed MRI scanner for knee imaging. It’s performance was to be validated via clinical testing, and required a specialised leg support to do so. In particular, to allow for the scanners rotation and tilt, it could only accommodate one leg at a time. And so, the aim of this project was to design, make, and test a single leg support that could be used with the scanner for imaging.

A bridge-like design with two support pillars was selected to provide the stability required for high quality imaging. The support was kept detached from the chair to simplify design and manufacture.

Since we didn’t have regular access to the MRI scanner, a collapsible mock-up was built for the testing phase. It was designed to simulate the geometric constraints of the machine in use. This was also used for preliminary research, to determine comfortable seating positions to design around. 

The required degrees of freedom (DOF) were then determined in order to design mechanisms to allow for each, including:

    •    Height adjustment (Blue)

    •    Support rotation, facilitated by:

    •    Base translation (yellow)

    •    Support column rotation (red)

    •    Leg support extension (green)

     

                     

The final prototype allowed for rapid rotation, translation, and height adjustment to ensure patient comfort. Additionally, the leg is supported by an interchangeable 3D printed profile, which can be swapped to suit varying patient physiology. The support can be quickly and compactly integrated with the MRI scanner’s base via aluminium extrusions.

The final prototype underwent extensive load testing to ensure it could support the design loads, and user testing to verify comfort and usability.