Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
SCREW BASED STATIC ANALYSIS OF A 4-DoF 3T1R FULLY DECOUPLED PARALLEL MANIPULATOR
Submission Author:
Paulo Rossi , SC , Brazil
Co-Authors:
Paulo Rossi, Rodrigo Cerqueira Campos, Roberto Simoni, Andrea Piga Carboni
Presenter: Paulo Rossi
doi://10.26678/ABCM.COBEM2021.COB2021-0722
Abstract
The kinematic and static or kinetostatic analysis of parallel manipulators (PMs) is a critical parameter, especially for machining applications, due to the high-intensity forces. This paper aims to conduct a kinetostatic analysis of the 4-DoF 3T1R fully decoupled PM considering machining applications’ operational forces. An analytical kinetostatic analysis is performed through a combination of natural coordinates (NC) and Davies’ method. The NC method consists in defining points and vectors throughout the manipulator’s links and joints. Afterward, by defining vector-loop equations starting from a known point, it is feasible to calculate every joint’s position through the NC method. Additionally, employing a numerical method, it is achievable to compute the joints’ positions. Therefore, applying the obtained results as inputs for the static analysis, it is possible to formulate the network action matrix through the screw theory applied to Davies’ method. Ultimately, eliminating the linear dependent variables makes it possible to reach the magnitude vector concerning the operational forces and moments. Since the kinetostatic analytical model is determined, a comparison regarding a numerical finite element analysis (FEA) developed through a CAD model is performed. The analytical model presented a mean error of 3.47% regarding the output torque and indicated a one-to-one correspondence between the input and output forces. The 4-DoF 3T1R PMs, like the studied one, may represent a practical alternative for both widely used machining centers and machining robots. Decoupled architecture presents a straightforward kinematic analysis, trivial workspace volume, decoupled motions, and well-conditioned performance indices. These properties are desirable for machining applications. The analytical kinetostatic model is validated by comparing its results with the FEA, indicating how reliable is the 4-DoF 3T1R fully decoupled PM regarding the machining effort.
Keywords
Parallel manipulator, stiffness analysis, screw theory, Davies method, Schönflies Motion
