Development of a 2-DOF electrostatic haptic joystick for MRI/fMRI applications

This paper describes the development of a 2-DOF electrostatic haptic joystick designed for neuroscience studies in an MRI/fMRI. The joystick is fabricated using non-magnetic materials and actuated by two high-power electrostatic motor units which produce various force fields in the horizontal plane. The electrostatic motor is a synchronous drive and thus the positioning of the joystick is achieved in an open-loop control. As for force sensing, a 2-DOF force sensor is developed using non-magnetic materials and optical fibers so as to measure interaction force with a user; hence, the haptic rendering is based on the admittance control scheme that respects the rule of force-in and position-out. The operation of both the actuators and force sensor respects non-magnetic principles. Thus, the haptic joystick into which these components are integrated is expected to have high MR compatibility, although the evaluation of the MR compatibility is beyond the scope of this paper. In this paper, the device performance is evaluated in the normal environment, which verifies the operation of the unique electrostatic haptic device.