Conceptual Design and Dimensional Synthesis of a Reconfigurable Hybrid Robot

2004 ◽  
Vol 127 (3) ◽  
pp. 647-653 ◽  
Author(s):  
Meng Li ◽  
Tian Huang ◽  
Dawei Zhang ◽  
Xueman Zhao ◽  
S. Jack Hu ◽  
...  

This paper deals with the conceptual design of a novel four-degree-of-freedom (dof) modularized robot which is composed of a 2-dof parallel mechanism plus a 2-dof rotating head attached to the moving platform. Patented with the name Bicept, the robot is the two-dimensional version of the Tricept robot and is designed as a reconfigurable module that can readily be integrated with 1-dof feed mechanism or a fixed base in order to form a set of reconfigurable robots with parallel-serial architecture. The dimensional synthesis of the 2-dof parallel mechanism as a component of the Bicept robot is also carried out by solving a one-dimensional nonlinear equation associated with the strut-length constraint. The dimensional parameters corresponding to various width-height ratios of the work space are obtained via examples.

2017 ◽  
Vol 41 (5) ◽  
pp. 922-935
Author(s):  
HongJun San ◽  
JunSong Lei ◽  
JiuPeng Chen ◽  
ZhengMing Xiao ◽  
JunJie Zhao

In this paper, a 3-DOF translational parallel mechanism with parallelogram linkage was studied. According to the space vector relation between the moving platform and the fixed base, the direct and inverse position solutions of this mechanism was deduced through analytical method. In addition, the error of the algorithm was analyzed, and the algorithm had turned out to be effective and to have the satisfactory computational precision. On the above basis, the workspace of this mechanism was found through graphical method, which was compared with that of finding through Monte Carlo method, and there was the feasibility for analyzing the workspace of the mechanism by graphical method. The characteristic of the mechanism was analyzed by comparing the results of two analysis methods, which provided a theoretical basis for the application of the mechanism.


2015 ◽  
Vol 28 (1) ◽  
pp. 49-67 ◽  
Author(s):  
M. D. Korzec ◽  
P. Nayar ◽  
P. Rybka

Abstract A spatially two-dimensional sixth order PDE describing the evolution of a growing crystalline surface h(x, y, t) that undergoes faceting is considered with periodic boundary conditions, as well as its reduced one-dimensional version. These equations are expressed in terms of the slopes $$u_1=h_{x}$$ u 1 = h x and $$u_2=h_y$$ u 2 = h y to establish the existence of global, connected attractors for both equations. Since unique solutions are guaranteed for initial conditions in $$\dot{H}^2_{per}$$ H ˙ p e r 2 , we consider the solution operator $$S(t): \dot{H}^2_{per} \rightarrow \dot{H}^2_{per}$$ S ( t ) : H ˙ p e r 2 → H ˙ p e r 2 , to gain our results. We prove the necessary continuity, dissipation and compactness properties.


1973 ◽  
Vol 15 (2) ◽  
pp. 114-122 ◽  
Author(s):  
J. G. A. Lovegrove ◽  
J. G. Williams

A theoretical analysis is given which illustrates the rôle of gravity forces in solids conveying. A one-dimensional solution for flow in an extruder channel is used to investigate the nature of the solution and a more precise, two-dimensional, version is then developed.


Author(s):  
Yufeng Qu ◽  
Jingjun Yu ◽  
Guanghua Zong ◽  
Shusheng Bi

A bending moment and a tension/compression force are two types of commonly used load patterns in loading test for mechanical components. A great number of simulator types available for the two loads have been reported widely. However, current types mainly focus on the single load pattern and only one-dimensional bending moment can be achieved. With the increasing demand of the mechanical part performance, it is urgent to build a more complex testing environment. In this situation, a novel compound load simulator capable of outputting single multi-dimensional load and compound load patterns gradually catches the attention of the researchers. The development of parallel mechanism (PM) supplies a new direction to the field of simulators, whereas there is still shortage of effective types and design principles. In this paper, type synthesis of the compound load simulators outputting the bending moment and tension/compression force is introduced. First of all, the relationship between load patterns and degree-of-freedom (DOF) of parallel mechanism is derived. Based on the derivation, the DOF correspondence with a two-dimensional pure bending moment is two-dimensional rotation and that with a tension/compression force is one-dimensional translation. Furthermore, a typical 3-PRS PM as a representative of the PM with 2R1T DOF is studied and the analysis reveals that there is parasitic motion during its two-dimensional rotation. The undesired parasitic motion will bring additional load to the part, such as shear force. Then the special characteristics of PM meeting the requirement of outputting pure bending moment are proposed. Finally, a graphical approach is utilized to synthesize the effective types of the compound simulator.


Author(s):  
A.L. Melkonian ◽  
D.A. Nikolaev

В статье предлагается метод, реализация которого позволит единообразно решать задачи об установившихся колебаниях конструкций, моделируемых квазиодномерными моделями. Суть метода состоит в коррекции и модификации значений инерционно-жесткостных характеристик такой модели, а так же внешней нагрузки, на нее действующей. При реализации метода учет влияния дополнительных факторов, усложняющих картину вибрации, осуществляется автоматически. В качестве примера рассмотрена задача о совместной вибрации судового корпуса и его конструктивного модуля в случае сравнительно небольшой протяженности района их сопряжения. Проанализированы первые варианты решения авторами задачи. Для плоского варианта задачи о совместной вибрации судового корпуса и конструктивного модуля выполнен анализ дополнительной нагрузки. Сформирована обобщенная матрица инерции конечного элемента модели судового корпуса в точке сопряжения. Приведена обобщенная матрица инерции для случая присоединения модуля L-образной формы. Предложен алгоритм расчета параметров вибрации (на основе дискретного варианта метода парциальных откликов). Выведены формулы для парциальных откликов и парциальных параметров, необходимые при реализации предложенного алгоритма.The article proposes a method, the implementation of which will uniformly solve the problem of steady-state oscillations of сотstructures modeled by quasi-one-dimensional models. The method consists in correcting and modification the values of the previous inertial-stiffness characteristics of such a model, as well as the external load acting on it.. When implementing the method, the influence of additional factors complicating the picture of vibration is taken into account automatically. The problem of joint vibration of the ships hull and its structural module in the case of a relatively small length of the area of their contact is considered. The authors analyzed the first variants of solution of the problem. For the two-dimensional version of the problem of joint vibration of the ships hull and structural module, the analysis of the additional load is performed. A generalized inertia matrix of the finite element of the ship hull model at the contact point with the L- element is formed. The algorithm of calculation of parameters of a vibration (on the basis of a discrete variant of a method of partial responses) is offered. Formulas for partial responses and partial parameters necessary for the implementation of the proposed algorithm were created.


Recent work has shown that it is possible to predict surface parameters measured digitally from a surface profile by means of three points on the autocorrelation function. The weakness of this work has been that only one-dimensional parameters have been evaluated. The present contribution extends the theory to include two-dimensional parameters of the surface which are expressed in terms of between four and seven points on the autocorrelation function depending on the type of surface. It is shown that this technique provides an alternative to traditional mapping methods. It is shown also that as a general rule results obtained from the discrete analysis do not converge to those obtained from the continuous theory. The nature and magnitude of the differences between the two approaches are discussed in detail. Finally, the theoretical results are confirmed experimentally and the general significance of discrete methods reviewed.


2012 ◽  
Vol 252 ◽  
pp. 107-110
Author(s):  
Yan Bing Ni ◽  
Wen Xia Guo ◽  
Fa Yang Luo

This paper deals with the dimensional synthesis of a planar parallel mechanism for wafer transfer with kinematics performance. Under the relationship between workspace and parametric, a kinematics performance index, which is composed of the conditioning number of the Jacobian matrix and the motion resolution, is considered as the evaluation criterion. And a new index which is proposed by considering both the mean value and fluctuation of the pre-mentioned index is used to optimally design the dimensional parameters. It is testified that the optimal dimensional parameters can satisfied with the kinematics performance.


1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.


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