Optimum Design of a 3R Robot with a Parallelogram Five-Bar Mechanism for Dexterous Workspace by Using Metaheuristic Algorithm

The kinematic design of a machine or mechanism is an important stage in the design methodology. A dexterous workspace for a robot manipulator is a outstanding characteristic that must be considered in the kinematic design, because it permit to reach the points of the workspace with different orientation. With this objective in mind, an optimization problem is formulated. A defined dexterous workspace is taken as an objective function. The design variables are lengths of the links and the angles of the links. The no collision between links are included as constraints. This paper describes the use of metaheuristic optimization techniques such as differential evolution (DE) to solve the above problem. A mechanism is incorporated in the DE algorithm in order to improve its behavior. This mechanism incorporates information of the base and the difference vectors of good trial vector, in an attempt to generate better individuals in the same direction. This mechanism guides the evolution of the population toward a better zone without sacrificing the search capabilities of the DE algorithm. The design of a robot with three revolute joints (3R robot) is considered as a numerical example.