A Haptic Interface Based on Potential Mechanical Energy to Investigate Human Motor Control using fMRI

This paper describes a mechanical interface to use in conjunction with fMRI, in order to infer the brain mechanisms of human motor learning. Innovative mechanical concepts based on gravity and elastic forces were used to generate typical stable and unstable dynamic interactions at the hand during multijoint arm movements. Two designs were retained and implemented from MR compatible materials. The first uses a spring constrained between two specially designed surfaces and the other a capstan to transform the force induced by a groove carved on a shaft. These two degree-of-freedom mechanical interfaces have been constructed and tested. The use of a capstan mechanism was found to be limited by excessive friction, however, the method using a machined surface provides a simple and effective interface to investigate human motor control