Development and Control of a 3DOF MRI-Compatible Haptic Device


Through the use of functional magnetic resonance imaging (fMRI) in conjunction with a haptic device, it is possible to study changes in brain activity while a patient undergoes rehabilitation-like protocols. By measuring changes in brain activity of a patient undergoing neurorehabilitation during fMRI, optimal patient-specific therapy regimens might be obtained. This research aims to develop, characterize, and control a parallel three degrees of freedom magnetic resonance (MR) compatible haptic device, called the MR-SoftWrist, which can measure and support wrist movements during fMRI. Through a series elastic actuation (SEA) architecture, the device achieves accurate force control and can implement rehabilitation-like protocols. An MR-compatible design is achieved by using Delrin and brass for structural materials, non-magnetic ultrasonic motors for actuation, and custom phosphor bronze extension springs as the series elastic elements. Current projects include complete characterization of the MR-SoftWrist, implementation of impedance controllers on the device, advanced MR-compatibility analyses, and validation with human subjects.