Dimensional synthesis of a spherical parallel manipulator based on the evaluation of global performance indexes

Abstract

In this work, the dimensional synthesis of a spherical Parallel Manipulator (PM) with a 3PSU-IS kinematic chain is presented. The goal of the synthesis is to find a set of parameters that defines the PM with the best performance in terms of workspace capabilities, dexterity and isotropy. The PM is parametrized in terms of a reference element, and a non-directed search of these parameters is carried out. First, the inverse kinematics and instantaneous kinematics of the mechanism are presented. The latter is found using the screw theory formulation. An algorithm that explores a bounded set of parameters and determines the corresponding value of global indexes is presented. The concepts of a novel global performance index and a compound index are introduced. Simulation results are shown and discussed. The best PMs found in terms of each performance index evaluated are locally analyzed in terms of its workspace and local dexterity. The relationship between the performance of the PM and its parameters is discussed, and a prototype with the best performance in terms of the compound index is presented and analyzed.

Manipulator Performance Measures - A Comprehensive Literature Survey

“…Such global indices measure the overall performance of the manipulator in some average sense. It is important to note here that, high values of a local performance index do not always translate into high values for its global version [9], and the converse is also true [10].…”

“…The kinematic conditioning index is upper-bound at 100%. A manipulator with a KCI of 100% is an isotropic manipulator ( [10], [49]) i.e., all the singular values of the Jacobian are similar at the condition of minimum singular value.…”

“…Puglisi et al [10] noted that sometimes GCI may overrate the performance of a manipulator by ignoring small regions of poor manipulator performance, which may sometimes be unacceptable in practice.…”

Solving kinematics and stiffness of a novel n(2-UPS/PS+RPS) spatial hyper-redundant manipulator

“…In order to enrich the architectures and develop the theory of SHRMs, a novel n(2-UPS/PS+RPS) SHRM is proposed and analyzed in this paper. In the application field of the robot, some PMs with constrained legs [15][16][17][18] are frequently used to enhance the stiffness and motion precision. Motivated by this concept, a novel 2-UPS/PS+RPS PM is proposed and used as the individual module of the novel SHRM.…”

Dimensional synthesis of a 3-DOF translational parallel manipulator considering kinematic dexterity property

“…The dimensional optimal design, a process to find the best suitable design parameters with respect to certain performance indices, becomes an inevitable step when designing and developing a parallel manipulator. The parallel manipulators with optimal kinematic parameters are destined to possess dramatically better performance compared with those without optimization [3], [11].…”