The aim of this paper is to present a systematic approach for the structural synthesis of Assur groups from Baranov chains, based on group theory. An Assur group can be represented as a ...vertex-colored graph of a Baranov chain, in which a detached vertex of the graph is colored with a distinct color. To obtain the results presented herein, the synthesis of Baranov chains has been extended to planar rigid chains with up to 17 links. Thus, an algorithm based on group theory and graph theory is applied to obtain all Assur groups with up to 16 links. The detached vertices are selected by determining the orbits of the automorphism group of the graph, such that no isomorphic Assur groups are generated in the process. The results are compared with the values found in the literature, in order to verify possible inconsistencies and reconcile existing values.
•Application of group theory to the symmetry analysis of Baranov chains.•Reconciliation of synthesis results for Assur groups with up to 12 links.•Presentation of a new result for the synthesis of Baranov chains with up to 17 links.•Presentation of a new result for the synthesis of Assur groups with up to 16 links.
The ankle and leg represent an anatomical-functional complex, the role of this complex being to support the body weight in an orthostatic position and to ensure movement, according to the terrain. ...Therefore, the leg has a static role as well as a dynamic role of equal importance. Ankle joint traumas have an immediate effect on joint instability, so that there is a mobility limitation or even mobility lose of this joint, the ankle needing rehabilitation therapy. A trend of the last decades, in terms of research in the field of robotics, is that of the field of rehabilitation, which aims to improve the rehabilitation process, from the primitive mechanisms currently used, to higher technologies. This trend occurs as a result of the growing number of the aging population, which requires assistance after the occurrence of various accidents. In this paper, structural synthesis of an ankle rehabilitation platform is presented.
The planar mechanisms with articulated bars and gears (which we will simply note MeBaRd) are part of the general planar mechanics category. Although structural structural studies have been carried ...out 7, the structural synthesis of bars and wheels can be approached as a distinct problem. Some papers refer directly to a certain class of mechanisms, such as planetary mechanisms 1, 2, others stop on subsystems with zero mobility, called structural groups with toothed elements 6, 8. In this paper, developing some ideas presented in 3, 5, a general algorithm for unitary structural synthesis of MeBaRd was developed and developed, having the input parameters: M - the degree of mobility and N - the number of contours.
•A general method is proposed for analyzing the DOF of new deployable linkage units.•Multi-layer and multi-loop deployable linkage units are synthesized systematically.•Three mobile assembly modes of ...the new deployable units are established.•Many novel umbrella-shaped deployable mechanisms based on new units are developed.
This paper aims to construct a novel family of umbrella-shaped deployable mechanisms based on new multi-layer and multi-loop spatial deployable linkage units. Firstly, a general method is proposed for analyzing the degree-of-freedom (DOF) of the deployable units by identifying independent geometrical constraint equations of them. Then, multi-layer and multi-loop deployable units are synthesized systematically based on structural modules and DOF constraint conditions. Finally, three mobile assembly modes of the new deployable units are established, and many novel umbrella-shaped mechanisms are obtained by assembling the deployable units. This paper greatly extends our previous work on the deployable mechanism design based on two-layer and two-loop deployable units in breadth and in depth, and presents new design methods as well as many novel umbrella-shaped deployable mechanisms with potential applications in space exploration and civil engineering.
•A new algorithm for detecting degenerate structures in PGTs is formulated .•Analytical detection is simple to implement manually or fully automated.•During the automatic detection process, the ...adjacency matrix is the only input.•A method for removing binary strings from rooted parent graphs is described.•Counterexamples and unexplored cases were successfully tested.
For a given number of links and degrees of freedom, several methods were proposed to enumerate the entire set of planetary gear trains. Acceptable solutions necessitate the detection of embedded locked sub-chains during the enumeration process. Previously published methods detect degenerate structures via combinational analysis or manual decomposition, with the process becoming more involved as the number of links grows. A matrix-based method for inspecting the presence of locked sub-chains is proposed in this work. The new method is based on the sequential removal of binary strings from rooted-parent graphs. A sub-graph is said to be locked if it becomes a structure with zero degrees of freedom under single or repeated application of binary strings deletion. The new degeneracy detection method is very efficient, comprehensive, and systematic for the automatic detection of locked sub-chains during the structural synthesis of PGTs. The locked sub-chain is uniquely determined regardless of the complexity of the system or its graph representation. Several examples are presented including some counterexamples and unexplored cases. A MATLAB program with the adjacency matrix as the only input is developed for the automatic detection of locked sub-chains.
Structural analysis and U–Pb geochronological study on zircons from the southern Chinese Altai (the Kalasu area, SE of the Altai city) show that the Cambro-Ordovician accretionary wedge (ca. ...520–492 Ma) underwent four major geological events: 1) emplacement of Early Devonian magmas (ca. 410–400) associated with formation of a volcano-sedimentary cover, 2) major Middle Devonian (ca. 390–374 Ma) tectono-metamorphic event, 3) Late Devonian-Early Carboniferous folding without apparent metamorphism, and 4) a regional folding with localized Early Permian high- to ultrahigh-temperature reworking (ca. 300–280 Ma). The Early Devonian magmatism is characterized by emplacement of mafic rocks and granitoids in the centre of the NE-SW profile, coevally with granitoid magmatism and rhyolite volcanism in the southwest and northeast, respectively. The whole volcano-sedimentary and magmatic edifice was transposed by sub-horizontal metamorphic fabric associated with variable metamorphic degrees in different areas ranging from greenschist facies in the northeast (mu + bi±g) to amphibolite facies in the southwest (st + g ± sill) and granulite facies in the centre (g + sill+kfs). This metamorphic architecture, distribution of magmatism and character of metamorphic zircon populations allow to correlate these areas with upper, middle and lower orogenic crust that developed during important vertical shortening and horizontal flow in Middle Devonian. Subsequently, the whole edifice was affected by regional NE-SW trending upright (possibly Late Devonian-Early Carboniferous) folding. Finally, Early Permian shortening produced NW-SE trending regional upright folds in the southwest and northeast and a crustal-scale vertical, tabular deformation zone in the centre. The Permian deformation is accompanied by granulite facies (kfs + cd + sill+g) metamorphism and anatexis reworking the Devonian lower orogenic crust, with extensive resetting and growth of new zircons and with intrusions of Permian granites and gabbros. This study suggests that the Early Permian event was related to massive perturbation of thermal structure of the mantle lithosphere due to the collision of the Junggar arc with the Chinese Altai terrane.
•Altai accretionary wedge shows polycyclic tectono-metamorphic evolution.•Early Devonian mafic-granitoid magmatism and volcano-sedimentary cover.•Regional Middle Devonian greenschist to granulite facies sub-horizontal event.•Devono-Carboniferous NE-SW regional upright folding, no metamorphism.•Early Permian NW-SE regional upright folding, localized vertical HT-UHT extrusions.
•We present a comprehensive review on the structural synthesis methods for various plane KCs and mechanisms.•The idea of intelligent design based on the automatic synthesis of mechanisms is ...discussed.•The presented review discusses the history of structural synthesis of mechanisms and the recent research progress.•The presented review concludes the research trends and future work in this area.•The presented review offers theoretical guidance for people engaged in creative design of mechanisms.
The creative design of mechanisms has been widely believed as one of the most important branches in the theory of mechanisms. Beside, the structural synthesis of kinematic chains (KCs) of mechanisms has been well-known as a fundamental technique for establishing novel theories towards intelligent design of mechanisms. This has thus motivated an increasing number of researchers to devote their efforts to exploiting new methods and techniques for structural synthesis of mechanisms over the past half century. In this paper, we present a comprehensive review on the structural synthesis methods for various plane KCs and mechanisms, including contracted graphs of KCs, non-fractionated and fractionated simple joint KCs, inversions of KCs, KCs with prismatic pairs, multiple joint KCs, Baranov trusses and Assur groups, as well as the automatic sketching of KCs. Moreover, the idea of intelligent design based on the automatic synthesis of mechanisms is discussed. The presented review discusses the history of structural synthesis of mechanisms and the recent research progress, and concludes the research trends and future work in this area, offering theoretical guidance for people engaged in the structural synthesis and intelligent design of mechanisms.
•A novel method for synthesizing GPMs with configurable moving platforms.•Five closed-loop configurable platforms with integrated end-effectors.•The serial limbs and the redundantly actuated hybrid ...limbs are enumerated.•The relationships among all kinds of limbs are revealed.•A novel family of 4/5/6-DOF GPMs with configurable platforms is presented.
A Conventional Parallel Manipulator (CPM) usually uses a rigid moving platform as the end-effector to connect serial legs. Since serial legs independently support the platform, kinematic joints are embedded into the rigid moving platform. However, the moving platforms of Generalized Parallel Manipulators (GPMs) are not limited to rigid bodies. The introduction of configurable platforms with integrated end-effectors allows for providing a multipoint connection with the environment. As a result, the functionality of parallel manipulators can be further extended. Resulting from the property of the platform, a significant challenge of connecting moving platforms with serial limbs is posed. This paper puts forward a systematic method for synthesizing parallel manipulators with configurable platforms. To realize the cooperation of the integrated end-effectors, the multi-drive hybrid limbs are designed base on the screw theory. According to the constraint synthesis method, a novel class of parallel manipulators with configurable platforms is constructed. Then the examples with different motion patterns are offered to corroborate the effectiveness of the proposed method. At last, driving schemes and the potential applications of the derived manipulators are discussed.
•This paper presents an automatic method to synthesize kinematic chains with prismatic pairs (RP-chains).•A new algorithm based on the vertex degree and edge weight is developed to detect ...isomorphism.•The synthesis results of RP-chains with 6–14 links are provided, and results with more than 8 links are new.•Our results are reliable, while counterexamples have been found by us when using the existing methods.•Our work is helpful to create mechanisms with prismatic pairs and other types of mechanisms.
Mechanisms that contain prismatic pairs (P-pairs) are widely used in industry. Synthesizing kinematic chains with P-pairs is a pivotal step in the conceptual design of mechanisms with P-pairs. However, most synthesis methods for plane kinematic chains in the literature focused on the chains with only revolute pairs (R-pairs), those chains with P-pairs were less discussed. This paper presents a fully automatic method for the structural synthesis of plane kinematic chains with P-pairs. A new algorithm based on the parameters of degree, weight, degree-sequence and weight-sequence is developed to detect isomorphism. The algorithm is simple, efficient, reliable and decodable. The synthesis results of kinematic chains with up to four P-pairs and up to 14 links are provided. Except for the results of 6- and 8-link 1-DOF kinematic chains, others are new and have not been reported in the literature. Our results are extremely reliable, while counterexamples have been found by us when using the existing methods. The present work is helpful to design mechanisms with P-pairs, and can be extended to mechanisms with other types of kinematic pairs.
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