MANIPULATOR TRAJECTORY SYNTHESIS FOR MINIMAL VIBRATIONAL-EXCITATION DUE TO THE PAYLOAD

As a manipulator is forced to track a desired trajectory, the required actuating torques (forces) may excite the natural modes of vibration of the robot manipulator. The harmonic content of the actuating torque s and the relative magnitude of each harmonic indicate which of the sy stem modes could be excited and the level of excitation that may be re ached. In a recent study, the authors have studied the effects of the payload mass, size, and end-effector holding location on the vibration al excitation of robot manipulators during the motion. [1]. In the pre sent paper, based on the aforementioned study, a method is developed t o synthesize trajectories, that produce minimal vibrational excitation in the presence of a payload. By following such trajectories, load ca rrying robot manipulators can be operated at relatively higher speeds. As an example, trajectories for point to point motions with minimal p otential vibrational excitation in the presence of payload are synthes ized for a spatial 3R manipulator. For a given payload mass, the effec ts on the optimal trajectory of the object:size and the location that it is held by the end-effector of the manipulator are determined. A nu mber of related topics are discussed.