Performance Enhancement of a Haptic Arm Exoskeleton

A high-quality haptic interface is typically characterized by low apparent inertia and damping, high structural stiffness, minimal backlash, and absence of mechanical singularities in the workspace. In addition to these specifications, exoskeleton haptic interface design involves consideration of space and weight limitations, workspace requirements, and the kinematic constraints placed on the device by the human arm. In this paper, the authors present the redesign of an existing five degree-of-freedom haptic arm exoskeleton. The redesign efforts focus primarily on ensuring smooth operation of the exoskeleton’s moving parts to minimize backlash, reducing cost and build time by simplifying the design, and increasing the torque output while continuing to use electric actuators for ease of control. The accompanying computer control system was developed in parallel with the mechanical redesign effort. The newly redesigned exoskeleton presented is capable of providing kinesthetic feedback to the joints of the lower arm and wrist of the operator, and will be used in future work for robot-assisted rehabilitation and training.