THE EFFECTS OF THE MANIPULATOR TYPE ON THE VIBRATIONAL-EXCITATION DURING MOTION

A method for determining the relationship between the structural type of a manipulator and its susceptibility to motion induced vibrational excitation is developed. The method is then used as a basis for determ ining an average for potential resonant energy transfer to a robot man ipulator,system by the higher harmonics of its actuating torques (forc es) while tracking trajectories that are distributed within a represen tative task space. The higher harmonics refers to the harmonics of the actuating torques with frequencies above the highest trajectory harmo nic frequency. The average potential resonant energy transfer is used as a measure to determine the susceptibility of the different types of manipulators to motion induced vibrational excitation. From the vibra tion and control points of view, manipulator types that do not demand high frequency actuating torque harmonics are more desirable, since th e natural modes of vibration of mechanical systems are most likely to be excited by the higher harmonics of the actuating torques and becaus e of practical dynamic response limitations of all mechanical systems. The primary objective of this paper is the presentation of the method s involved. As examples, plane two and three degrees-of-freedom manipu lators constructed with revolute and prismatic joints are studied in s ome detail. Numerical calculations are presented for the two degrees-o f-freedom manipulators. Copyright (C) 1996 Elsevier Science Ltd.