DEVELOPMENT OF THE ANTHROPOMORPHIC ROBOT WITH CARBON-FIBER EPOXY COMPOSITE-MATERIALS

The material for the robot structure should have high specific stiffne ss (stiffness/density) to give positional accuracy and fast maneuverab ility to the robot. Also, the high material damping is beneficial beca use it can dissipate the structural vibration induced in the robot str ucture. This cannot be achieved through conventional materials such as steel and aluminum because these two materials have almost the same s pecific stiffnesses which are not high enough for the robot structure. Moreover, steel and aluminum have low material dampings. Composites w hich usually consist of very high specific modulus fibers and high dam ping matrices have both high specific stiffnesses and high material da mpings. Therefore, in this work, the forearm of an anthropomorphic rob ot which has 6 degrees of freedom, 70 N payload and 0.1 mm positional accuracy of the end effector was designed and manufactured with high m odulus carbon fiber epoxy composite because the magnitudes of the mass and moment of inertia of the forearm of an anthropomorphic robot are most important due to its farthest position from the robot base. Two p ower transmission shafts which deliver the power of the motors positio ned at the rear of the robot forearm to the wrist and the end effector were also designed and manufactured with high modulus carbon fiber ep oxy composite to reduce weight and rotational inertia. The mass reduct ion of the manufactured composite forearm was 15.9 kg less than the st eel forearm. The natural frequencies and damping capacity of the manuf actured composite arm were measured by the fast Fourier transform meth od and compared to those for the steel arm. From the test, it was foun d that both the fundamental natural frequency and damping ratio of the composite arm of the robot were much higher than those of the steel a rm.