The material used for robot structures should have specific stiffness (stiffness/density) to give positional accuracy and fast maneuverability to the robot manipulator. Also, high material damping is beneficial because it can dissipate the structural vibration induced in the robot manipulator structure. Both the high specific stiffness and damping of the material cannot be achieved through conventional materials such as steel and aluminum because they have almost the same low specific stiffness and low material damping. However, fiber reinforced polymeric composite materials that consist of high specific modulus fiber and high damping matrix have both high specific stiffness and high material damping. In order to increase specific stiffness and damping, in this work, the third robot arm of the articulated robot manipulator that has 6 d.f. (degrees of freedom), 60 N payload and 0.1 mm positional accuracy of the end effector was designed and manufactured with carbon fiber epoxy composite material. The composite third robot arm was composed of the composite yoke, the composite cylindrical tubular structure and the aluminum flange. After manufacturing the composite arm, the dynamic property and operational performance were compared to those of the hybrid third robot arm that was composed of the aluminum yoke, the composite tubular structure and the aluminum flange. From the experiments, it was found that the composite third robot arm contributed to improving both the dynamic characteristics and operational performance of the articulated robot. (C) 1997 Elsevier Science Ltd.
