Stiffness analysis of overconstrained parallel manipulators

Abstract

The paper presents a new stiffness modeling method for overconstrained parallel manipulators with flexible links and compliant actuating joints. It is based on a multidimensional lumped-parameter model that replaces the link flexibility by localized 6-dof virtual springs that describe both translational/rotational compliance and the coupling between them. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations for the unloaded manipulator configuration, which allows computing the stiffness matrix for the overconstrained architectures, including singular manipulator postures. The advantages of the developed technique are confirmed by application examples, which deal with comparative stiffness analysis of two translational parallel manipulators of 3-PUU and 3-PRPaR architectures. Accuracy of the proposed approach was evaluated for a case study, which focuses on stiffness analysis of Orthoglide parallel manipulator.

CAD-based approach for identification of elasto-static parameters of robotic manipulators

“…However, in spite of computational convenience and better accuracy, the second approach can be hardly applied to many industrial manipulators (where links may be nonhomogeneous, their shape is quite complex and cross-section is non-constant, etc). For instance, for the Orthoglide foot (Figure 2), even a four-beam approximation provides an accuracy of only 30-50% [27]. To achieve desired accuracy, here it is proposed to apply the FEA-based identification methodology that was firstly introduced in [27] but needs some further development.…”

“…Other enhancements include the link approximation by several beams, but it gives rather modest improvement in accuracy. Further advance in this direction (applicable to the links of complicated shape) led to the FEA-based identification technique that involves virtual loading experiments in CAD environment and stiffness matrix estimation using dedicated numerical routines [27]. The latter essentially increased accuracy of the VJM-modeling while preserving its high computational efficiency.…”

Dynamic Modeling of a 2-RPU+2-UPS Hybrid Manipulator for Machining Application

“…More comprehensive study on machining dynamics could be further considered upon the model developed in this work. In this light, the stiffness modeling of the manipulator is needed and can be obtained with a variety of available approaches (Wu et al (2015a), Pashkevich et al (2009)). These works are tasks of future study.…”

Mechatronic Scanning System with Integrated Micro Electro Mechanical System Position Sensors

“…One of them is the so-called Finite Element Analysis (FEA) [4,7,13]. The FEA method has been proven to be the most accurate and reliable one, since the joints are represented with their real sizes and shapes.…”