Structural synthesis of two-layer and two-loop spatial mechanisms with coupling chains

Ding, Huafeng; Cao, Wen-ao; Chen, Ziming; Kecskeméthy, Andrés

doi:10.1016/j.mechmachtheory.2015.05.015

Cited by 38 publications

(6 citation statements)

References 24 publications

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“…The Hoberman switch-pitch ball, 1 magic balls, 2 and magic cubes 3 are mechanisms of the multi-loop kind, well known in commercially available toys, while planar multi-loop mechanisms lack sufficient mobility to realize functionally flexible manipulation tasks. 4,5 On the other hand, two-layer, two-loop mechanisms 6,7 have low stiffness and limited load-carrying capacity; hybrid mechanisms [8][9][10][11] have limited workspace. In this regard, Li et al 12 proposed a novel multi-loop mechanism for space applications, which, in this paper, is referred to as the double-tripod multiloop mechanism (DTMLM).…”

Section: Introductionmentioning

confidence: 99%

Mobility and singularity analyses of a symmetric multi-loop mechanism for space applications

Ángeles

Guo

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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A symmetric, double-tripod multi-loop mechanism (DTMLM), for aerospace applications, is the subject of this paper. Its mobility and singularity are analyzed, while introducing a novel tool, the cell-division method for singularity analysis, applicable to multi-loop mechanisms. The key principle of this method lies in replacing the singularity analysis of the original multi-loop mechanism with: (1) that of an equivalent simpler parallel mechanism; (2) the constraint analysis between loops; and (3) the singularity analysis of simpler kinematic subchains. Then, the mechanism is transformed into a simpler, equivalent parallel mechanism with three identical kinematic subchains. Its mobility and singularity are analyzed based on screw algebra, which leads to a key conclusion about the geometric properties of this mechanism. Results show that: (a) the DTMLM has three degrees of freedom (dof), i.e., two rotational dof around two intersecting axes lying in the middle plane of the mechanism, and one translational dof along the normal to the said plane (2R1T); and (b) the singularities of the 3-RSR parallel mechanism are avoided in the DTMLM by means of prismatic joints, singularities in the DTMLM occurring on the boundary of its workspace. Thus, the DTMLM has a 2R1T mobility everywhere within its workspace. When a set of multi-loop mechanisms of this kind are stacked as modules to assemble a multi-stage manipulator for space applications, the modules can be designed so that, under paradigm operations, all individual loops operate within their workspace, safe from singularities.

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Section: Introductionmentioning

confidence: 99%

Mobility and singularity analyses of a symmetric multi-loop mechanism for space applications

Ángeles

Guo

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Xun et al [23] presented a novel rhombohedral multi-loop coupling mechanism with three DOFs. Ding et al [24] formulated a general type synthesis method for two-layer and two-loop mechanisms. Parallel mechanism also belongs to MLMs, and the analysis method of parallel mechanism can provide valuable reference for the analysis of MLMs.…”

Section: Introductionmentioning

confidence: 99%

Degree-of-Freedom Analysis and Structural Synthesis of a Class of Host–Parasite Multi-Loop Mechanisms

Wei

Dong

2021

Preprint

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The method of analyzing the mechanism in series, parallel and hybrid modes can no longer meet the requirements of analyzing multi-loop mechanisms (MLMs), especially multi-loop mechanisms with passive degrees of freedom(P-DOFs).This study presents an approach to analyzing sub-degree-of-freedom (sub-DOF) relations in a class of MLMs with P-DOFs (P-DOFs) as well as structurally synthesizing these mechanisms. First,the DOFs of mechanisms with P-DOFs are decomposed and combined,and two methods—multi-loop serial connection and multi-loop stacking—are formulated to establish MLMs with P-DOFs.Second, a DOF space (DOF-S) model is generated.Host–parasite (H–P) MLMs are proposed, and various types of parasitism are analyzed. Finally, various DOF distribution patterns in H–P MLMs are analyzed based on real-world examples. The results show the following. H–P mechanisms are a class of MLMs with P-DOFs. For an H–P mechanism, its DOFs can be longitudinally and centrally, transversely and centrally, or comprehensively optimally distributed in the DOF-S by selecting a suitable type of parasitism. The H–P-type palletizing robot prototype developed in this study is able to self-balance. This demonstrates that the comprehensive optimization of DOF distribution is effective. This study enriches the theoretical knowledge on MLMs, which are extensively applied in fields such as aerospace, industrial robotics, and numerical-control machine tools.

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“…Xun et al 23 proposed a novel rhombohedral three-DOF multi-loop mechanism. Ding et al 24 proposed a general method for the structural synthesis of two-layer two-loop mechanisms. Wang et al 25 carried out a kinematic analysis of the 2UPR-2RPU parallel mechanism, which is also a multi-loop mechanism.…”

Section: Introductionmentioning

confidence: 99%

A host–parasite structural analysis of industrial robots

Wei

Cai

Gong

et al. 2020

International Journal of Advanced Robotic Systems

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Most driving torques in serial industrial robots are used to overcome the weight of the robot. Although actuators account for a large proportion of the total mass of a robot, they have yet to become a positive factor that enables the robot to achieve gravity balance. This study presents a host–parasite structure to reconstruct the distribution of actuators and achieve gravity balance in robots. First, based on the characteristics of tree–rattan mechanisms, a method for calculating the degrees of freedom and a symbolic representation method for the distribution of branched chains are formulated for host–parasite mechanisms. Second, a configuration analysis and optimization method for host–parasite structure-based robots and a robot prototype are presented. Finally, four host–parasite mechanisms/robots (A, B, C, and D) are compared. The results are as follows. If more parasitic branched chains are added to the yz plane, the loads along axes 2 and 3 become more balanced, which significantly increases the stiffnesses of the mechanism in the y- and z-directions ( Ky and Kz, respectively). If the additional branched chains are closer to the site of maximum deformation, the stiffness of the mechanism in the z-direction ( Kz) increases more significantly. Of the four mechanisms, mechanism D has the best overall performance. The joint torques of mechanism D along axes 2 and 3 are lower than those of mechanism A by 99.78% and 99.18%, respectively. In addition, Kx, Ky, and Kz of mechanism D are 100.56%, 336.19%, and 385.02% of those of mechanism A, respectively. Moreover, the first-order natural frequency of mechanism D is 135.94% of that of mechanism A. Host–parasitic structure is conducive to improving the performance of industrial robots.

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Structural synthesis of two-layer and two-loop spatial mechanisms with coupling chains

Cited by 38 publications

References 24 publications

Mobility and singularity analyses of a symmetric multi-loop mechanism for space applications

Mobility and singularity analyses of a symmetric multi-loop mechanism for space applications

Degree-of-Freedom Analysis and Structural Synthesis of a Class of Host–Parasite Multi-Loop Mechanisms

A host–parasite structural analysis of industrial robots

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