Robotic manipulators with remotely-actuated joints: implementation using drive-shafts and u-joints

A popular configuration for the actuation of robotic manipulators with articulated joints is to have motors directly attached to the joints. This approach does not involve any transmission elements between the actuators and the joints and it is advantageous in many respects. However, in certain cases this configuration may not be appropriate and manipulators with remotely-actuated joints may be desirable. In this article different alternatives for the implementation of remote actuation would be discussed and a case study would be presented relevant to a robotic arm, which was designed to operate inside a closed cylindrical magnetic resonance imaging (MRI) scanner for the performance of image-guided interventions. The transfer of motion to the articulated joints of the arm was implemented using drive shafts and universal joints (u-joints). Experimental testing of the arm highlights issues relevant to remote actuation