Publication | Open Access
Formation of High-Speed Motion Pattern of a Mechanical Arm by Trial
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1978
Year
Robot KinematicsEngineeringMechanical EngineeringMotor ControlAdvanced Motion ControlKinesiologyMechanicsMechanical ArmSystems EngineeringKinematicsServo SystemHigh-speed Motion PatternHealth SciencesMechanical DesignMechatronicsMotion SynthesisComputer EngineeringHigh SpeedMotion ControlFeedforward ControlAerospace EngineeringMechanical SystemsHuman MovementRoboticsVibration ControlFeed Forward (Control)
High‑speed motion of a mechanical arm requires precise trajectory control, but servo time lag prevents direct application of trajectory functions, and dynamic torque compensation to address this demands highly accurate arm models that are costly to develop. The study proposes a trial‑and‑correction method to adjust the reference function, thereby avoiding the need for highly accurate arm models. A stable correcting algorithm is developed that iteratively refines the reference function based on trial outcomes, with its stability and convergence theoretically analyzed. Experiments on a six‑degree‑of‑freedom arm controlled by a digital computer confirm that the algorithm yields stable trial‑correction and rapid convergence of the servo response to the desired trajectory.
High-speed motion of a mechanical arm is necessary to speed up a job done by the arm. In high speed, however, the desired trajectory of motion of the arm cannot be obtained simply by applying the trajectory function to the servo system as the reference function because the time lag in the servo system is not negligible.A solution to this problem is to apply dynamically compensating computed torques to the servo system. By this method, however, for increasing the accuracy of the mathematical model of the arm necessary to compute the compensating torques, a very large effort would be required. To avoid this difficulty, an alternative method of correcting the reference function by trial will be useful. Repeating a proper process of trial and correction, the reference function which realizes the desired pattern of trajectory may be obtained.In this paper, correcting algorithm of a reference function for this method is investigated theoretically from the standpoint of stability or convergency of the process of trial and correction, and a stable correcting algorithm is obtained. Through the experiment using a mechanical arm of six degrees of freedom controlled by a digital computer, it is confirmed that the process of trial and correction by this algorithm is stable and the response of the servo system converges rapidly to the desired pattern of trajectory.