Analysis of a Tele-Operated MRI-Compatible Vane Actuator for Neuromuscular Facilitation in Hemiparetic Limbs

This paper analyzes the suitability of pneumatically driven, MRI-compatible vane actuators for stroke rehabilitation, particularly functional recovery of hemiparetic limbs. Hemiparesis patients suffer a sudden loss of motor skills in the upper-limb due to brain injury, such as stroke. As an emerging physio-therapy technique for hemiparesis, named repetitive facilitation exercise, or RFE, a therapist manually applies brief mechanical stimuli to the peripheral target muscles (e.g., tapping, stretching of tendon/muscle) followed by wrist pronation/supination immediately before a patient intends to produce a movement with the muscle. In an earlier study, a robotic system that replicates the mechanical tendon stimulation part of RFE procedure in MRI with the required timing precision has been developed and tested by the authors to investigate the underlying principles of functional recovery via RFE. This work presents the design of a vane actuator that fits into the tight space in MR-scanners, and analyzes its dynamic performance via a detailed pneumatic system model. The analysis indicates that a pneumatically driven, tele-operated vane actuator can satisfy the dynamic requirements of the targeted rehabilitation procedure.