Abstract: A surgical robotic platform operates within a constrained space of an imaging scanner in which a patient resides. The platform includes a gross positioning stage configured to be located outside of the constrained space An end-effector having a rotatable shaft is extendable from the gross positioning stage and into the constrained space of the imaging scanner. The shaft has a proximal end operatively coupled to the positioning stage outside of the constrained space and a distal end configured to be located in the constrained space. The distal end has a medical instrument gripper for holding a medical instrument used in a percutaneous procedure. The end-effector further includes a joint arrangement operatively coupling the shaft to the medical gripper for providing motion to the medical instrument gripper for enabling position and/or orientation control of the medical instrument. A drive module controls the joint arrangement.