Welcome to fMRIrobot.org, a site designed exchanged information about the use of fMRI-compatible robot devices for the study of motor control and learning. Particularly, we describe here our experiences with the construction and use of a pneumatic fMRI compatible robotic arm.

The device was developed 2001-2003 in the computational motor control lab under direction of Reza Shadmehr at Johns Hopkins University. The people responsible for the design and engineering of the robot are Mike Turner, Jamie Hartwell, Maneesh Dewan, Jörn Diedrichsen, and Reza Shadmehr. Machining for he first device was performed in the BME shop by Jay Burns. Since then we have improved design and control of the arm. Current versions of the arm, including updated control software, have been developed by Jörn Diedrichsen (now at University College London, UK).

The robot is completely MR compatible. The linkages are made of carbon fibre and plastic composites. The joints of the robot house cermaic ball bearings to facilitate smooth motion of the robot. The robot is actuated with a pair of two-way, air-driven cylinders that house pistons. An air-compressor is situated outside of the magnet room. The air pressure is regulated by four servo valves that are mounted very close to the cylinders. This force is transmitted to the joints of the robot through a linkage. The resulting torques are in turn transmitted to the handle of the robot via another set of linkage. The result is a sensation of force on the subject's hand. Optical encoders measure position of the robot's links. This signal is sent to the computer and software calculates position of the robot's handle. This position is displayed to the subject via a video monitor.

System overview

The technical knowledge, code, etc, is put by us into the public domain. We would like this technology to be available to a wide audience and do not intend to patent any content made public here. You are free to use, change, and redistribute knowledge and code displayed here according to the rules of the GNU Public License and the GNU Free Documentation License. Proper credit must be given to the original source.

Please feel free to contact us with any questions, comments, new contributions, etc.

best wishes,

Reza Shadmehr
Jörn Diedrichsen