Overconstrained Mechanisms Derived From RPRP Loops

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Kuan-Lun Hsu ◽  
Kwun-Lon Ting
Keyword(s):  
Computer Aided Design ◽  
Random Search ◽  
Modular Approach ◽  
Input Output ◽  
Assembly Strategy ◽  
Revolute Joints ◽  
Prismatic Joints ◽  
Overconstrained Mechanisms ◽  
Aided Design ◽  
Four Bar Linkage

This paper addresses the assembly strategy capable of deriving a family of overconstrained mechanisms systematically. The modular approach is proposed. It treats the topological synthesis of overconstrained mechanisms as a systematical derivation rather than a random search. The result indicates that a family of overconstrained mechanisms can be constructed by combining legitimate modules. A spatial four-bar linkage containing two revolute joints (R) and two prismatic joints (P) is selected as the source-module for the purpose of demonstration. All mechanisms discovered in this paper were modeled and animated with computer-aided design (CAD) software and their mobility were validated with input–output equations as well as computer simulations. The assembly strategy can serve as a self-contained library of overconstrained mechanisms.

Over-Constrained Mechanisms Derived From RPRP Loops

2018 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Kuan-Lun Hsu
Keyword(s):  
Computer Aided Design ◽  
Random Search ◽  
Modular Approach ◽  
Input Output ◽  
Assembly Strategy ◽  
Revolute Joints ◽  
Computer Aided ◽  
Prismatic Joints ◽  
Aided Design ◽  
Four Bar Linkage

This paper addresses the assembly strategy capable of deriving a family of over-constrained mechanisms systematically. The modular approach is proposed. It treats the topological synthesis of over-constrained mechanisms as a systematical derivation rather than a random search. The result indicates that a family of over-constrained mechanisms can be constructed by combining legitimate modules. A spatial four-bar linkage containing two revolute joints (R) and two prismatic joints (P) is selected as the source-module for the purpose of demonstration. All mechanisms discovered in this paper were modeled and animated with computer aided design (CAD) software and their mobility were validated with input-output equations as well as computer simulations. The assembly strategy can serve as a self-contained library of over-constrained mechanisms.

A New Family of Bricard-Derived Deployable Mechanisms

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Hailin Huang ◽  
Bing Li ◽  
Jianyang Zhu ◽  
Xiaozhi Qi
Keyword(s):  
Large Volume ◽  
Computer Aided Design ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
New Family ◽  
Revolute Joints ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

This paper proposes a new family of single degree of freedom (DOF) deployable mechanisms derived from the threefold-symmetric deployable Bricard mechanism. The mobility and geometry of original threefold-symmetric deployable Bricard mechanism is first described, from the mobility characterstic of this mechanism, we show that three alternate revolute joints can be replaced by a class of single DOF deployable mechanisms without changing the single mobility characteristic of the resultant mechanisms, therefore leading to a new family of Bricard-derived deployable mechanisms. The computer-aided design (CAD) models are used to demonstrate these derived novel mechanisms. All these mechanisms can be used as the basic modules for constructing large volume deployable mechanisms.

Overconstrained Analysis of Five-Link Spatial Single Loops With Revolute and Prismatic Joints

2000 ◽  
Author(s):  
Qiong Jin ◽  
Lu-Bin Hang ◽  
Ming Zhang
Keyword(s):  
Theoretical Basis ◽  
The Other ◽  
New Method ◽  
Input Output ◽  
Displacement Analysis ◽  
Single Loop ◽  
Prismatic Joints ◽  
Existence Conditions ◽  
Closure Conditions ◽  
Overconstrained Mechanisms

Abstract A new method on determining the existence conditions of overconstrained mechanisms is presented in this paper, which is used for studying the spatial single loop generally possessing one configure. This method is very effective to distinguish finite and infinite solutions of displacement analysis, and can analytically deduce the input-output equations. It is elucidated that the existence conditions of overconstrained mechanism consist of the overconstrained conditions and the closure conditions, and that the independence of the closure conditions should be further discussed. On the other hand, the existence conditions of two known 5-link overconstrainded mechanisms are verified and corrected. This method also provides a theoretical basis for finding new oveconstrained mechanisms.

Function Generation With Finitely-Separated Precision Points Using Geometric Constraint Programming

2006 ◽  
Author(s):  
Edward C. Kinzel ◽  
James P. Schmiedeler ◽  
Gordon R. Pennock
Keyword(s):  
Constraint Programming ◽  
Computer Aided Design ◽  
Linear Equations ◽  
Geometric Constraints ◽  
Geometric Constraint ◽  
Function Generation ◽  
Design Software ◽  
Aided Design ◽  
Four Bar Linkage ◽  
Non Linear Equations

This paper explains how Geometric Constraint Programming can be applied to solve function generation problems with finitely-separated positions using a number of different mechanisms. Geometric Constraint Programming uses the sketching mode of commercial parametric computer-aided design software to create kinematic diagrams whose elements are parametrically related so that when a parameter is changed, the design is modified automatically. Geometric constraints are imposed graphically through the user interface, and the numerical solvers integrated into the software solve the relevant systems of non-linear equations without the user explicitly formulating those equations. A key advantage of using Geometric Constraint Programming for function generation is that the same approach can be applied to any mechanism, so no unique algorithms are required. Furthermore, because the implementation is relatively straightforward regardless of the chosen mechanism, the designer can quickly and easily generate solutions for a large number of precision points and/or with complex mechanisms to provide a very accurate match to the desired function. Examples of function generation with a four-bar linkage, a six-bar linkage, and a seven-bar linkage illustrate the benefits of the proposed methodology.

Integration of Geometry and Analysis for Vehicle System Applications: Continuum-Based Leaf Spring and Tire Assembly

2015 ◽  
Vol 11 (3) ◽  
Author(s):  
Zuqing Yu ◽  
Yiguan Liu ◽  
Brian Tinsley ◽  
Ahmed A. Shabana
Keyword(s):  
Computer Aided Design ◽  
Contact Forces ◽  
Leaf Spring ◽  
Dynamic Simulations ◽  
Constraint Equations ◽  
Revolute Joints ◽  
New Models ◽  
Analysis System ◽  
Aided Design ◽  
Algebraic Constraint

The development of new and complex vehicle models using the absolute nodal coordinate formulation (ANCF) and multibody systems (MBS) algorithms is discussed in this paper. It is shown how a continuum-based finite element (FE) leaf spring and tire assembly can be developed at a preprocessing stage and integrated with MBS algorithms, allowing for the elimination of dependent variables before the start of the dynamic simulations. Leaf springs, which are important elements in the suspension system of large vehicles, are discretized using ANCF FEs and are integrated with ANCF tire meshes to develop new models with significant details. To this end, the concept of the ANCF reference node (ANCF-RN) is used in order to systematically assemble the vehicle model using linear algebraic constraint equations that can be applied at a preprocessing stage. These algebraic constraint equations define new FE connectivity conditions that include the leaf spring shackle/chassis assembly, tire flexible tread/rigid rim assembly, tire/axle assembly, and revolute joints between different vehicle components. The approach presented in this paper allows for using both gradient deficient and fully parameterized ANCF FEs to develop the new models. In order to develop accurate leaf spring models, the prestress of the leaves and the contact forces between leaves are taken into consideration in the ANCF models developed in this investigation. Numerical results are presented in order to demonstrate the use of the computational framework described in this paper to build continuum-based leaf spring/tire assembly that can be integrated with complex vehicle models. The results of this paper also demonstrate the feasibility of developing a CAD (computer-aided design)/analysis system in which the geometry and analysis mesh of a complete vehicle can be developed in one step, thereby avoiding the incompatibility and costly process of using different codes in the flexible MBS analysis.

Dynamic rolling analysis of triangular-bipyramid robot

Robotica ◽  
2014 ◽  
Vol 33 (4) ◽  
pp. 884-897 ◽  
Author(s):  
Yaobin Tian ◽  
Yan-An Yao
Keyword(s):  
Kinematic Analysis ◽  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Step Length ◽  
Computer Aided ◽  
Zero Moment ◽  
Aided Design ◽  
Four Bar Linkage ◽  
Three Degrees Of Freedom ◽  
Rolling Robot

SUMMARYIn this paper a rolling robot resembling the shape of a triangular-bipyramid is proposed. The robot has three degrees of freedom and is formed by connecting two tripod mechanisms with three spherical joints. By kinematic analysis, the robot can be viewed as a planar four-bar linkage. Further, its dynamic rolling ability is discussed by Zero Moment Point (ZMP) analysis. We show that the robot has the capability to roll, adjust its step length, and switch rolling directions. These functions are verified by a series of simulations with a CAD (computer-aided design) model and experiments with a prototype.

Minimization of Inertia-Induced Forces in Spherical Four-Bar Mechanisms. Part 1: The General Spherical Four-Bar Linkage

1983 ◽  
Vol 105 (3) ◽  
pp. 471-477 ◽  
Author(s):  
G. S. Gill ◽  
F. Freudenstein
Keyword(s):  
Quadratic Programming ◽  
Computer Aided Design ◽  
High Speed ◽  
Programming Technique ◽  
Trade Off ◽  
Design Procedures ◽  
Computer Aided ◽  
Aided Design ◽  
Four Bar Linkage ◽  
Input Torque

Computer-aided design procedures have been developed for the optimum mass distribution of the links of high-speed spherical four-bar linkages. The analysis, which includes a quadratic-programming technique, allows an optimum trade-off between shaking forces, shaking moments, bearing reactions, and input-torque fluctuation. The results are illustrated in the case of a Hooke joint and a wobble-plate linkage.

Computer Aided Design and Analysis of the Rack and Pinion Mechanism

1992 ◽  
Author(s):  
D. Srinivas ◽  
Steven N. Kramer
Keyword(s):  
Computer Aided Design ◽  
General Procedure ◽  
Full Range ◽  
Fortran Program ◽  
Linkage Mechanism ◽  
Function Generation ◽  
Transmission Angle ◽  
Method Of Solution ◽  
Aided Design ◽  
Four Bar Linkage

Abstract The general procedure for synthesizing the rack and pinion mechanism for six precision conditions is developed. To illustrate the method, the mechanism has been synthesized in closed form for generating both four prescribed path points with input coordination and two positions of function generation. This is the extension of the work reported earlier on this mechanism where only three path precision points were satisfied. The rack and pinion mechanism has a number of advantages over the conventional four bar linkage mechanism. First, since the rack is always tangent to the pinion, the transmission angle has a constant optimum value of 90 degrees minus the pressure angle of the pinion. Second, because both translation and rotation of the rack are possible, multiple outputs are available. Generation of monotonic functions for a wide variety of motion, and nonmonotonic functions for the full range of motion as well as nonlinear motions, are other advantages of this mechanism. The rack and pinion mechanism has applications in the packaging industry, in toys, and automotive steering mechanisms. In this work, the mechanism is made to satisfy a number of practical design constraints such as a completely rotatable input crank and others. Also, structural errors for function generation are calculated to give an estimate of the accuracy of the mechanism. The method of solution developed in this work uses the complex number method of mechanism synthesis and a FORTRAN program is written to find the solutions for any input.

APPréCIE: A Computer Package for the Simulation and Design of Mechanical Grippers

1993 ◽  
Author(s):  
Clément M. Gosselin ◽  
Sylvain Lemieux
Keyword(s):  
Computer Aided Design ◽  
Practical Problem ◽  
Input Output ◽  
Large Database ◽  
Dimensional Changes ◽  
Computer Aided ◽  
Cad Tool ◽  
Aided Design ◽  
Robotic Applications ◽  
Simulation Package

Abstract This paper presents a simulation package developed for the computer-aided design of simple mechanical grippers. The program includes a relatively large database of gripper architectures which can be accessed interactively by the designer. The kinematic analysis of each of the generic architectures has been performed symbolically at the programming stage and explicit expressions of the input-output equations as well as the velocity relationships have been coded. This provides an accurate and fast interactive response. The kinematic dexterity and the gripping index can be plotted and are updated automatically when dimensional changes are made. Finally, a graphic animation of the grippers is available. An example is given here to illustrate the application of the design package to a practical problem. This CAD tool could be of great help in the context of the design of mechanical grippers which is one of the key challenges in advanced robotic applications.

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