Industrial robot equipped with articulated arm unit

Abstract

Disclosed herein is an industrial robot equipped with an articulated arm unit which includes a first arm, second arm, a holder case and a holder. The basal end portion is pivotally attached to a shoulder shaft, which is formed of a first and second shafts disposed on the same axis and rotatable independently from each other. A differential transmission mechanism is arranged over mutually-opposing end portions of the first and second shafts. First drive means is formed by the first shaft and first coupling means so as to rotate the holder. Second drive means is also formed by the second shaft and second coupling means so as to rotate the holder case. The second drive means is also provided with third coupling means, which is also connected to the differential transmission mechanism, so as to compensatively rotate the holder. Owing to the adoption of the above structure, the above industrial robot can actuate its holder or arms independently without developing any induced motion at other parts of the industrial robot. Since a compensatory mechanism is provided at a basal part of the arm unit for the holder, the free end portion to which a hand is attached can be constructed in a small size. It is easy to teach handling work to the above industrial robot.