A new method for type synthesis of parallel mechanisms using screw theory and features of genetic algorithms
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(2020) 42:615
TECHNICAL PAPER
A new method for type synthesis of parallel mechanisms using screw theory and features of genetic algorithms João Victor Borges Dos Santos1 · Roberto Simoni2 · Andrea Piga Carboni2 · Daniel Martins2 Received: 19 January 2020 / Accepted: 1 October 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract The type synthesis is a fundamental phase in the design of parallel mechanisms. The type synthesis process consists of a systematic approach to generate all possible mechanical structures that are capable of performing a determined movement. The type synthesis presents two main steps: (1) generation of limbs and (2) assembly of parallel manipulators. There are basically three main approaches for type synthesis of parallel mechanisms: screw theory, lie group of rigid body displacements and evolutionary morphology. This paper presents a new method that combines screw theory and characteristics of genetic algorithms. Using the proposed method, it was generated new solutions of 3-DOF limbs (2R1T and 1R2T) for parallel manipulators. Keywords Type synthesis · Parallel mechanisms · Generation of limbs · Genetic algorithm · Screw theory
1 Introduction
The type synthesis process can be divided into two steps:
The type synthesis is a systematic approach for the creation of new mechanisms and parallel manipulators. In the type synthesis process, a method is used to generate all possible mechanical structures with a determined kinematic performance [6, 12, 18]. To determine all possible mechanical architectures of parallel manipulators, that can produce a specific type of movement on the mobile platform, is still a challenging issue [25]. The type synthesis of parallel manipulators consists of generating all possible mechanical structures that can reach a determined type of movement on the mobile platform of the manipulator in relation to its fixed base [18].
Step 1—Generation of limbs It consists of generating kinematic chains that have a determined output movement. The type of joints and the geometrical relationship that they have with each other are fundamental in achieving this step. Step 2—Assembly In this step, the limbs generated in Step 1 are used for assembling the parallel mechanisms. The limbs are fixed between the base and the moving platform in order to achieve a determined output movement of the parallel mechanism.
Technical Editor: Adriano Almeida Gonçalves Siqueira. * João Victor Borges Dos Santos [email protected] Roberto Simoni [email protected] Andrea Piga Carboni [email protected] Daniel Martins [email protected] 1
Curtin University, Bentley, Australia
Federal University of Santa Catarina, Florianópolis, Brazil
2
2 Bibliography review Most of the existing works related to type synthesis of parallel manipulators are based on subgroups of displacement, screw theory and evolutionary morphology.
2.1 Subgroups of displacement approach Hervé [10] proposed to enumerate the subset of all possible movements that a rigid
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