Optimal Synthesis of Robot Manipulators Based on Global Dynamic Parameters

Abstract

The local nature of inertial, nonlinear, and coupling character istics of manipulators is an impediment to their optimal design. In this article, a method to represent and measure the global and posture-independent measures of inertia, coupling, and nonlinear forces is presented. A new concept, referred to as the global inertia ellipsoid, which represents the global iner tial characteristics of a manipulator, is introduced. The global inertia ellipsoid is obtained by considering a weighted distri bution of the end-effector position over the workspace of the manipulator. Based on this concept, four global parameters, representing the global nonlinear, coupling, and inertial char acteristics of the manipulator, are obtained. The number of global parameters does not change with the degrees of freedom or the complexity of the manipulator structure. A probabilistic or deterministic description of payload range can be included while designing the manipulator. Criteria for the optimal de sign of manipulators are presented in the form of an objective function of the global parameters. The method is illustrated by the design of a 2R manipulator, a 2R manipulator with given payload range, and a 3R manipulator. The extension of the concept of the global inertia ellipsoid to task placement and task planning is discussed.