A parametric study of robot arm vibration by simulation analysis

At present, most industrial robots are controlled with a semi-closed loop for controlling the movement of a robot arm by detecting the rotational angle and/or angular velocity of a driving motor. A robot system with such a structure is comprehensively analyzed by a computer simulation, considering not only an arm-dynamics system, but also a control system, driving system, and transmission system. Robot arm vibrations, and methods for their reduction are investigated by a parametric study. As a result, the following conclusions are obtained. (1) Characteristics of robot arm vibration. If the stiffness of the transmission system is thoroughly weaker than that of the control system, the lowest natural vibration of the arm-dynamics system becomes predominant. The arm motion can be described by primary natural vibration of a mathematical model with spring-connected rigid links, in which the stiffness of the joints are equal to those of the transmission system. If the stiffness of the control system is sufficie...