Abstract

The relationship between the structural type of a manipulator and its susceptibility to motion induced vibrational excitation is examined. For manipulators of different type, the average potential resonant energy transfer to a robot manipulator system by the higher harmonics of the actuating torques (forces) necessary for tracking trajectories that are uniformly distributed within a representative task space are determined, and used as a measure of the potential for vibrational excitation during motion. The manipulators are kinematically and dynamically equivalent. From the vibration and control points of view, manipulator types that do not demand high frequency actuating torque harmonics are more desirable, since the natural modes of vibration of mechanical systems are most likely to be excited by the higher harmonics of the actuating torques, and because of practical dynamic response limitations of all mechanical systems. As examples, plane two and three degrees-of-freedom manipulators constructed with revolute and prismatic joints are studied. Numerical calculations of the aforementioned and the total expected (average) energy input and the corresponding variances are presented for the two degrees-of-freedom manipulators. A number of points of interest are discussed.

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