Magnetically compatible robots are required to develop haptic interfaces for neuroscience studies and MRI guided robots for minimally invasive interventions. This paper introduces an MR compatible master slave concept using a hydraulic transmission, and presents an operational robot able to work within an MRI/fMRI scanner and acquire images continuously during motion. It describes a magnetically inert actuator using a direct drive to power the hydraulic circuitry and a modular set of position and force/torque sensors that we have developed. These were integrated into a haptic interface prototype with on rotary degree of freedom, which can be used in conjuction with an fMRI. The MR compatibility was confirmed experimentally, and the performances show a manipulation accuracy of a few micrometers over a range of several centimeters, and forces up to several thousand Newton.

Force reflecting manual man-machine interfaces can provide the user with useful kinesthetic information in teleoperation tasks and virtual reality applications. In this paper we discuss the design of a novel spherical remote-center-of-motion manipulator for force reflection in a laparoscopic surgery simulation environment. A description of the pantograph-linkage based parallel structure is presented together with a discussion of its direct and inverse geometric models, instantaneous kinematics and statics, and usable workspace.