Mechanical design and optimization of a novel fMRI compatible haptic manipulator

In this paper, we present the mechanical design of a new fMRI compatible haptic interface with 3DOFs, based on electrical DC actuation, for the study of brain mechanisms of human motor control. The 1DOF manipulator, which was evaluated successfully on the compatibility with fRMI environment in the preliminary experiments, was extended to the implementation of a 3DOFs parallel manipulator with 3- UPU kinematics. Kinematic properties were studied in different configurations to select the stroke of the prismatic joint and the radius difference between the moving platform and the base. Due to the dimensional constraints imposed by the fMRI environment, the choice of the dimensions and the adopted mechanical solution was a result of an optimization process presented in this work. A further optimization of the mechanical design was then conducted in order to reduce the torque requested to the actuators for gravity compensation and improve the mechanical stiffness with elastic compliance of the manipulator. The final design resulted in a system capable of satisfying all the environment and user requirements.