2-DOF fMRI-Compatible Haptic Interface for Bimanual Motor Tasks with Grip/Load Force Measurement

Robotic systems are invaluable tools for the investigation of sensorimotor control of action, as they can influence motion in a controlled manner and precisely record timing, trajectory and interaction forces. In order to better understand the dynamics of human action, it is also necessary to examine the related brain function. Functional magnetic resonance imaging (fMRI) is a valuable tool to measure task related changes in brain activation and combine these two approaches, but poses severe constraints on the development of robotic devices. Here, we present a two- degrees-of-freedom haptic interface for bimanual motor tasks with grip and load force measurement, which adheres to the stringent compatibility and safety requirements of fMRI. The robotic technology is based on earlier developments, which evolved through material compatibility tests and developments made within Touch-HapSys. The highly flexible hydrostatic transmission allows placing the two linear actuators with a stroke of 30 cm in various manners for interaction with single-handed or bimanual movements. As an extension, they can be fixed to an adjustable table to actuate an XY-stage for interaction with planar movements over a workspace of 15×15 cm 2. This system opens up new ways of exploring the nature of amplitude (force and position) and timing constraints in the sensorimotor control of action in healthy subjects and neurological patients.