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JMR Editorial – May 2011 As we move into the second decade of the 21st century, we can identify three research trends that we can expect to persist into the future. They are the analysis and synthesis of (i) spatial mechanisms and robotic systems, (ii) compliant linkage systems, and (iii) tensegrity and cable-driven systems. In each case, we find t...
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Citations
... Many approaches for kinematic analysis and synthesis of mechanisms and manipulators are based on the derivative of loop-closure equations using the vector, matrix and screw methods [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. In this case, polynomials of high degrees are obtained [43,44]. ...
This paper addresses the structural-parametric synthesis and kinematic analysis of the RoboMech class of parallel mechanisms (PM) having two sliders. The proposed methods allow the synthesis of a PM with its structure and geometric parameters of the links to obtain the given laws of motions of the input and output links (sliders). The paper outlines a possible application of the proposed approach to design a PM for a cold stamping technological line. The proposed PM is formed by connecting two sliders (input and output objects) using one passive and one negative closing kinematic chain (CKC). The passive CKC does not impose a geometric constraint on the movements of the sliders and the geometric parameters of its links are varied to satisfy the geometric constraint of the negative CKC. The negative CKC imposes one geometric constraint on the movements of the sliders and its geometric parameters are determined on the basis of the Chebyshev and least-square approximations. Problems of positions and analogues of velocities and accelerations of the considered PM are solved to demonstrate the feasibility and effectiveness of the proposed formulations and case of study.
... Then, examining the resulting polynomials using computers, depending on the assigned tasks, the kinematic analysis or synthesis is performed. McCarthy in his papers [14,15] shows the close relationship between the kinematics, synthesis, polynomials, and computations in the 21st century. In the considered approach of kinematic analysis and synthesis of mechanisms and manipulators, it is rather difficult to obtain the polynomials; moreover, with the complication of the structures of mechanisms and manipulators, the formation of polynomials becomes more complicated and their degree increases. ...
In this paper, methods of kinematic synthesis and analysis of the RoboMech class parallel manipulator (PM) with two grippers (end effectors) are presented. This PM is formed by connecting two output objects (grippers) with a base using two passive and one negative closing kinematic chains (CKCs). A PM with two end effectors can be used for reloading operations of stamped products between two adjacent main technologies in a cold stamping line. Passive CKCs represent two serial manipulators with two degrees of freedom, and negative CKC is a three-joined link with three negative degrees of freedom. A negative CKC imposes three geometric constraints on the movements of the two output objects. Geometric parameters of the negative CKC are determined on the basis of the problems of the Chebyshev and least-square approximations. Problems of positions and analogues of velocities and accelerations of the PM with two end effectors have been solved.
... In the macroscopic world, a mechanism is an assembly of mechanical parts linked together by joints in an open or closed chain, for example, the arm of a robot and four-bar linkage (McCarthy 2006). Mechanisms are used in machines so that they can successfully transmit forces, motion, and energy from the input to the output components. ...
Synonyms DNA nanomachines; DNA-based molecular machines ; DNA-based nanorobots; Dynamic DNA nanostructures Definitions DNA Mechanisms and Machines DNA mechanisms and machines are made by using DNA as materials to build the assembled links and joints. The links are formed by relatively rigid double-stranded DNA (dsDNA) bundles and the joints are constructed by flexible single-stranded DNA (ssDNA) segments or rigid components with geometrical constraints. Also, complaint DNA mechanisms can be designed by gently tuning the stiffness of dsDNA bundles. Driven by one or more linear or rotatory actuators, these DNA mechanisms can achieve a predetermined motion pattern much like macromachines. These DNA machines have shown promising applications in targeted drug delivery and biosensors.
... Afterwards, Crane III et al. [30] proposed a planar tensegrity parallel mechanism and completed its equilibrium analysis. Tensegrity systems have been identified as one of three main research trends in mechanisms and robotics for the second decade of the 21st century [31]. However, just a few references have stated the possibility of using tensegrity systems as water wave energy harvesters. ...
A tensegrity-based water wave energy harvester is proposed. The direct and inverse kinematic problems are investigated by using a geometric method. Afterwards, the singularities and workspaces are discussed. Then, the Lagrangian method was used to develop the dynamic model considering the interaction between the harvester and water waves. The results indicate that the proposed harvester allows harvesting 13.59% more energy than a conventional heaving system. Therefore, tensegrity systems can be viewed as one alternative solution to conventional water wave energy harvesting systems.
... Interactions between a robot end-effector and the external world occur frequently in practical applications, for example, in assembling operations and grasping tasks. Many efforts have been reported in literature, focusing on analysis, computation, control, and optimization of robotic systems stiffness and compliance [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Generally, such interactions can be represented by a generalized force vector acting on the end-effector (three scalar force components and three scalar moment components). ...
A manipulator control system, for which isotropic compliance holds in the Euclidean space E(3), can be significantly simplified by means of diagonal decoupling. However, such simplification may introduce some limits to the region of the workspace where the sought property can be achieved. The present investigation reveals how to detect which peculiar subset, among four different classes, a given manipulator belongs to. The paper also introduces the concept of control gain ratio for each specific single-input/single-output joint control law in order to limit the maximum gain required to achieve the isotropic compliance condition.
... The cable parallel manipulators (CPMs) are structurally similar to traditional parallel mechanisms except that in CPMs cables are used to manipulate objects instead of rigid links, which are generally known for simple configuration, high speed and load/weight ratio, large workspace, great stiffness and low price (McCarthy 2011;Zi et al. 2011;Otis et al. 2009). The preceding characteristics make the CPMs a promising alternative of the rigid-link mechanisms in many fields, such as real-time measurement, manipulation of heavy loads, wind tunnel testing, virtual reality interface and large radio telescope (Albus et al. 1993;Duan et al. 2009;Yang et al. 2010;Lau et al. 2011;Marc 2011). ...
Combining mobile cranes with the cable parallel manipulators (CPMs), a cooperative CPMs for multiple mobile cranes (CPMMCs) was designed in this paper. The kinematics were derived on the basis of the configuration of the CPMMCs, aiming at numerical estimation of workspace subject to the constraints on the cable tensions and mobile cranes’ structure. Kinematic error, caused by machining, assembly and operation, is one of the major error sources for CPMMCs during high-precision hoisting, which can be estimated by means of error modeling. Kinematics error model was established based on closed-loop vector method. The influences of different error sources on the accuracy are investigated with sensitivity analysis in statistics. Finally, the system is simulated with expected trajectory of the payload based on the established kinematics and error model of the CPMMCs. The simulation results not only provide rationale for design of the CPMMCs, but also of certain guiding significance in practical engineering application.
... Research in the topic of cable parallel manipulators (CPMs) is highly motivated and has a very strong interest as the modern engineering demand for such manipulators is growing rapidly. The CPMs are structurally similar to traditional parallel mechanisms, but differ in which cables are used instead of rigid links, which have potential advantages in terms of simple and light-weight structure, high acceleration capability, and easy reconfigurability [1][2][3]. For the preceding characteristics, the CPMs play an important role in many engineering fields, such as manipulation of heavy payloads for manufacturing and cargo handling, coordinate measurement, aircraft testing, super antenna, and haptic devices [4][5][6][7]. ...
This paper deals with the error modeling and sensitivity analysis of a hybrid-driven based cable parallel manipulator (HDCPM). The HDCPM has the advantages of both cable parallel manipulator and hybrid-driven planar five-bar mechanism. Kinematics analysis and error modeling are performed based on closed loop vector conditions and direct differential method. The error model derived for the proposed HDCPM has the ability to account for the original errors from kinematics parameters. In addition, the sensitivity analysis is also carried out to investigate the effects of 36 error sources of kinematics parameters on the end-effector of the HDCPM. A detailed example of the sensitivity of the end-effector's position coordinates for the HDCPM is presented in order to demonstrate the validity of the error modeling and sensitivity analysis developed.
... The necessity to deal with kinematics and statics simultaneously causes the displacement analyses of this kind of robots to be considerably more complicated than analogous tasks concerning rigid-link parallel manipulators [4][5][6]. According to McCarthy [7], the direct geometrico-static problem (DGP) of under-constrained CDPRs, which aims at determining the end-effector posture when all cable lengths are assigned, is a major challenge in current kinematics. ...
This paper studies the direct geometrico-static problem of under- constrained parallel robots suspended by 4 cables. The task consists in determining the end-effector pose and the cable tensions when the cable lengths are assigned. The problem is challenging, because kinematics and statics are coupled and they must be solved simultaneously. An effective elimination procedure is presented that provides the complete solution set, thus proving that, when all cables are in tension, 216 potential solutions exists in the complex field. A least-degree univariate polynomial free of spurious factors is obtained in the ideal governing the problem and solutions are numerically computed via both an eigenvalue formulation and homotopy continuation. Equilibrium configurations with slack cables are also considered.
... Accordingly, loop-closure and mechanical-equilibrium equations must be simultaneously solved and displacement analyses, which are aimed at determining the overall robot configuration when a set of n variables is assigned, become geometrico-static problems [2]. These are considerably more complex than displacement analyses of rigid-link parallel manipulators [11]. ...
This paper studies the direct geometrico-static analysis of under-constrained cable-driven parallel robots with 3 cables. The task consists in finding all equilib-rium configurations of the end-effector when the cable lengths are assigned. An interval-analysis-based procedure is proposed to numerically find the real solutions of the problem for a robot of generic geometry. Three equation sets obtained by different approaches are implemented in the problem-solving algorithm and a com-parison between the main merits and drawbacks of each one of them is reported.
... From the kinematic structure [28] point of view, the metamorphic mechanism is a kind of multimobility mechanism; the differ-ence is that the general multimobility mechanisms are controlled by the driver links and have only one mobility-configuration as a working configuration, but there are more mobility-configurations as working configurations of a metamorphic mechanism which is controlled by driver links and metamorphic elements of links or joints. ...
This paper presents a new way of structure composition of single-driven metamorphic mechanisms to develop a systematic and modularized structure synthesis methodology of metamorphic mechanisms based on augmented Assur groups (AAGs). Planar metamorphic mechanisms can hence be constructed based on the developed AAGs by applying the structure composition rule of general planar mechanisms formed by Assur groups (AGs). First, the one-mobility AAGs are introduced based on class II and class III AGs; the structure formulation and composition methodology of planar metamorphic mechanisms are then proposed based on the AAGs, and the basic problems including mobility and synthesis of constrained metamorphic working mobility-configuration are investigated. This leads to the investigation of the degenerated equivalent AGs of AAGs in the metamorphic process and the corresponding kinematic characteristics, providing references for kinematic synthesis of metamorphic mechanisms. Further, a typical spatial metamorphic group is introduced based on the concept of AAGs, and the structure formation and composition of spatial metamorphic mechanisms are presented. Examples show that both planar and spatial metamorphic mechanisms can be constructed by utilizing the one-mobility blocks extended from the AGs. [DOI: 10.1115/1.4006741]
