A new approach to enhance the stiffness of heavy-load parallel robots by means of the component selection

Fan, Shuai; Lan, Weibin; Song, Guangkui

doi:10.1016/j.rcim.2019.101834

Cited by 18 publications

(9 citation statements)

References 41 publications

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“…Under this scenario, the parallel robot can be regarded as a parallel robot with six generalized driving elements in the force analysis. 7 This means that any slight vibration on the mobile platform of the DPR occurs in the DOF directions and other constrained directions. Thus, for a DPR, two vibration systems can be obtained, where one has fewer DOFs and the other has six DOFs.…”

Section: Vibration Modelling Methodsmentioning

confidence: 99%

“…Note that the range of values for the joint clearances and the range of values for the stiffness of all branches are calculated based on equation (2), where the joint clearances and the stiffness of all component is given in our previous studies. 7 Natural frequencies. As commonly used physical parameters, the natural frequencies reflect the inherent vibration characteristics of the system.…”

Section: Numerical Casesmentioning

confidence: 99%

“…As a crucial issues for DPRs used as machine tools, vibration analysis is very important to the machining accuracy and surface finish of manufactured products. [5][6][7] The vibration analysis of parallel robots is complicated due to the highly nonlinear dynamics and multiple DOFs of the vibration model. 8,9 Despite these complications, scholars have obtained excellent insights into this field, and their research has mainly focused on four aspects: the construction of a vibration model, [10][11][12] the study of a control strategy, 13,14 the optimization of the vibrational performance [15][16][17] and the parametric design.…”

Section: Introductionmentioning

confidence: 99%

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Vibration modelling analysis of defective parallel robots as machine tools for aerospace parts machining

Fan,

Zhang,

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part B:

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The strict machining accuracy and surface finish requirements of manufactured products for aerospace parts make it particularly crucial to analyse the vibration performance of parallel robots as machining tools, which directly affects both of these factors. In this paper, a vibration modelling analysis for parallel robots with fewer-DOFs called defective parallel robots is presented, and the effects of four vibration models are also studied. The traditional spring-damping or elastic vibration models of two systems are presented, and the corresponding uncertain vibration systems are developed by considering the effects of gravity and the uncertain joint clearances. Taking a drilling defective parallel robot as an application example, four vibration models are derived, and the differences in natural frequency and vibration response are explored in numerical and experiment comparisons. The results shows that an uncertain system with six DOFs is closer to the experimental result (approximately 75.49%) than an elastic system (approximately 62.39%), which means that the accuracy has increased by 13.1%. The results of this paper reveal some of the reasons for the performance errors of the different vibration models for defective parallel robots, and the findings of this paper can provide a reference for the simplification and optimization of theoretical vibration models that ignore secondary factors.

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Section: Vibration Modelling Methodsmentioning

confidence: 99%

Section: Numerical Casesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vibration modelling analysis of defective parallel robots as machine tools for aerospace parts machining

Fan,

Zhang,

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…Compared with GA, PSO has the advantages of simple principle, few parameters, fast convergence and good memory. 26 Pu et al applied the DE algorithm to the optimization of a 6-PSS PM motion simulation, which result showed that DE algorithm is better than the GA in providing optimal solution by about 48.3%, about 9.3% in terms of time-consuming. 27 Although DE algorithm has many advantages, it is seldom used in stiffness optimization of PMs.…”

Section: Introductionmentioning

confidence: 99%

Stiffness analysis and optimization of an asymmetric 3T1R parallel mechanism

Zhu,

Ma,

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this paper, an asymmetric 3T1R parallel mechanism is proposed that has higher stiffness in specific directions. The stiffness model is established by using virtual spring theory, and the Cartesian stiffness matrix is obtained. The stiffness performance evaluation indices are deduced by the dimensionless parameterization method. Under the condition of satisfying the high-speed performance and dexterity, the optimal size parameters of the mechanism are got by using the DE (differential evolution) algorithm with stiffness performance as the index. By comparing the stiffness performance atlases before and after the optimization, it is showed that the stiffness performance has been improved and the reachable workspace has been increased. The results verify the feasibility of the proposed performance indices and optimization algorithm.

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“…To meet the demand for high precision from the industry, the stiffness analysis of PMs is also essential in the pre-design stage, which should consider the influences of joints and links, and is also the basis of the multi-objective optimization and structural design of PMs [17,18]. Considering the influence and importance of stiffness on the precision of PMs, many progresses have been presented by the academic community for the stiffness characteristics of PMs, which are focused on the various methods of the stiffness modeling and performance evaluation index [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Elastostatic Stiffness Analysis for the US/UPS Parallel Manipulators

Zhang

Yang

2020

Mathematical Problems in Engineering

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The virtual joint method (VJM) cannot calculate the strain energy stored in each rod. In order to solve the problem, a modeling method of the elastostatic stiffness was investigated for the UP/UPS parallel manipulators (PMs), taking the example of the 6-SPS PM. The modeling method was based on screw theory, Castigliano’s theorem, and strain energy (where U, P, and S, respectively, denote universal, prismatic, and spherical joints). First, the actuator and constraint wrenches of the mechanism were obtained by screw theory. Second, compact limb stiffness matrices were obtained in terms of strain energy and Castigliano’s second theorem. Finally, analytic expressions for the overall stiffness matrix of the mechanism and the amplitudes of the actuator force were obtained by adopting the virtual work principle and the balance equation for the mobile platform. All relative errors between the results of the analytical model and the finite element model are below 2%, which validates the effectiveness of the elastostatic stiffness model. The virtual work index was adopted to evaluate the stiffness performance of the mechanism, and the results show that the stiffness is not only related to position and orientation but also closely related to the directions of external loads. It is also demonstrated that the method has general adaptability for the stiffness analysis for the US/UPS PMs, laying the foundation for further reasonable dynamic design and optimization of such manipulators.

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A new approach to enhance the stiffness of heavy-load parallel robots by means of the component selection

Cited by 18 publications

References 41 publications

Vibration modelling analysis of defective parallel robots as machine tools for aerospace parts machining

Vibration modelling analysis of defective parallel robots as machine tools for aerospace parts machining

Stiffness analysis and optimization of an asymmetric 3T1R parallel mechanism

Elastostatic Stiffness Analysis for the US/UPS Parallel Manipulators

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