Design Optimization of Gimbal Robotic Joints Based on Task Space Manipulability


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Abstract: Featuring a nonlinear novel design, Gimbal transmission, is a replacement for traditional robotic joints like gearboxes and revolute joints. This mechanism is one of the most recent types of nonlinear direct transmission (DT) methods in robots. As an alternative for traditional drive methodologies — herein called direct drive transmission (DD) methods, DT provides dynamic coupling and joint interaction attenuation while its capability to be adjusted for a desired task space point, smooth input output characteristic, and varying reduction ratio lead to a desired force and motion behavior for the whole manipulator. In this paper, design optimization of a gimbal mechanism used as a replacement of simple robotic revolute joints is investigated. Kinetostatic model of the robotic arm is made and based on Manipulability Ellipsoid analysis the amount of force at the tip of the manipulator is maximized and compared with the same quantity for a simple manipulator. The best design variables are found using Genetic Algorithm and it is shown that this replacement leads to greater forces at the tip of the manipulator in that desired direction.

Keywords: design, optimization, robotics, manipulators, genetic algorithms, robots