bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape Optimal Structural Design Using Boundary Elements and Minimum Compliance Techniques
Authors: Mota Soares C. A. , Rodrigues H. C. , Choi K. K.
Published: January 2010

Shape optimal design of two-dimensional elastic components is formulated using boundary elements. The design objective is to minimize compliance of the structure, subject to an area constraint. All degrees of freedom of the model are at the boundary and there is no need for calculating displacements and stresses in the domain. Formulations based on linear and quadratic boundary elements are developed. The corresponding nonlinear programing problem is solved by Pshenichny’s linearization method. The model is applied to shape optimal design of several elastic structural components. The advantages and disadvantages of the boundary element method over the finite element technique for shape optimal design of structures are discussed, with reference to applications.
Shape Optimization of Elastic Hollow Bars
Authors: Hou J. W. , Chen J. L.
Published: January 2010

In this paper a unified shape optimum design scheme, combining the material derivative and boundary parametrization is presented to find the optimal cross-sectional shapes of elastic hollow bars. Performance criteria can be the bending stiffness, the torsional rigidity, or the weight of the bar. The existence of a keyway (an example of geometric irregularity) can be considered as well. Material property can be either isotropic or anisotropic. Various numerical examples have been provided to show the validity of the presented approach.
A Theory for the Three-Dimensional Mating of Chamfered Cylindrical Parts
Authors: Gustavson R. E.
Published: January 2010

Assembly of real parts is usually a spatial phenomenon. Automated equipment which may perform the mating will often have inaccuracy much larger than the clearance of the parts to be assembled. To overcome that difficulty as well as prescribe the insertion force behavior, engineered compliance devices are being created. This paper desribes the requirements for the most complex assembly apparatus thus far attempted at CSDL; it also defines desirable characteristics for the chamfers on the mating parts.
Design and Analysis of Momentary-Dwell Mechanisms
Authors: Wang A. C. , Lee T. W.
Published: January 2010

This paper presents a general theory for the dwell characteristics and for the synthesis of momentary-dwell mechanisms. Dwell conditions are obtained from the simultaneous solution of a set of equations derived recursively through the differentiations of a general form of displacement equation. A general synthesis approach is presented. It involves the use of analytical solutions of the lower-order dwell criteria as initial estimates and the development of a computer-aided procedure to subsequently readjust the mechanism proportions by heuristic optimization. The proportions thus obtained represent tradeoffs among higher orders of dwell and various prescribed kinematic and dynamic characteristics. For most practical purposes, such a solution is useful and acceptable. The coupler-dwell mechanism is used to illustrate the theory and approach. In particular, two mechanisms design problems are investigated. One deals with the kinematic synthesis of a six-bar coupler mechanism with shockless dwell and with prescribed unlimited crank rotations as well as optimum transmission; and the other concerns the design of a chain-linkage drive, including an analysis on the effect of the chain dynamics.
Longitudinal Load Distribution Factor of Helical Gears
Authors: Tobe T. , Inoue K.
Published: January 2010

This paper deals with the longitudinal load distribution and the bending moment distribution of a pair of helical gears with a known total alignment error. The load distribution along the contact lines is calculated by the finite element method based on the plate theory including transverse shear deformation. Empirical formulas for both longitudinal load distribution factor and bending moment distribution factor are proposed for practical use. The load distribution factor in AGMA 218.01 is examined, and it is concluded that the load distribution factor is close to the calculated results if the value of unity is taken as the transverse load distribution factor.
Influence of Relative Displacements Between Pinion and Gear on Tooth Root Stresses of Spiral Bevel Gears
Authors: Winter H. , Paul M.
Published: January 2010

A measuring method for determining the tooth root stresses of spiral bevel gears is presented. Some basic results referring to amount, distribution, and direction of root stresses are discussed. Moreover, as an example, the influence of variations of the pinion mounting distance on these items is described.
Capacity Limits of the Largest Pairs of Carburized Gears to be Produced With Available Equipment
Authors: Hiersig H. M.
Published: January 2010

Independent from the application and from the expected probability of failure, each pair of gear wheels has an inherent power transmission capacity. Particularly the large-sized, carburized, and flank-ground gears are subjected to very different opinions in regard of their capacity. Recently published calculation methods, however, allow for a detailed determination of the ratings. The comparison of their relative results with actual applications thus seems of great interest in order to check the factors to be applied.
Load Sharing in a Planetary Gear Stage in the Presence of Gear Errors and Misalignment
Authors: Ma P. , Botman M.
Published: January 2010

A method of analysis is described of dynamic loads occurring in the planetary gear stages of the gearboxes of PT6 turboprop engines. The dynamic loads are important for the design of lightweight and durable components. A rigorous dynamic analysis, which includes the effects of nonlinear tooth stiffnesses, ring gear flexibility, gear errors and misalignments, is necessary to determine dynamic tooth loads and the load sharing among the planets. Results are presented of sample calculations for a typical gear stage.
A Direct Determination of the Instantaneous Kinematics of Fully Parallel Robot Manipulators
Authors: Mohamed M. G. , Duffy J.
Published: January 2010

Screw theory is applied to the study of the instantaneous kinematics of the end-effector platform of fully parallel robot type devices. The instantaneous motion of the end-effector is expressed directly in terms of the twists of the input-actuated joints and it is demonstrated that the twist representing the instantaneous motion of the end-effector platform is equal to the sum of its partial twists. A partial twist is defined as the twist representing the instantaneous motion of the end-effector when all but one of the input actuators are locked. The analysis presented forms a proper basis for the study of special configurations of parallel type devices.
Optimal Motion Programming of Robot Manipulators
Authors: Schmitt D. , Soni A. H. , Srinivasan V. , Naganathan G.
Published: January 2010

The objective of this paper is to develop a general approach to determine the optimal motion programs at the joints of a robot in order to perform a task between given work stations. The optimal joint motion programs are determined by minimizing the joint torque values. The results obtained by this technique are compared with some of the standard motion programs used in industries.
Whirl of High-Speed Rotors Driven by Dry or Lubricated Rollers
Authors: Wang S. , Seireg A.
Published: January 2010

This paper presents a computer-based simulation of the vibration and dynamic load conditions in rotors driven by dry or lubricated Hertzian contacts. The effect of clearance coefficient of friction, elastohydrodynamic film, number of drive rollers, and contact compliance on the rotor movement and the contact forces is investigated.
Spatial Kinematic Synthesis of Adaptive Hard-Automation Modules: An RS-SRR-SS Adjustable Spatial Motion Generator
Authors: Sandor G. N. , Yang S. P. , Xu L. J. , De P.
Published: January 2010

Purely mechanical, single-actuator adaptive hard-automation modules can perform highly repetitive simple tasks much more economically, energy-efficiently and accurately than multi-degree-of-freedom, multiple-actuator robotic manipulators. As an example, an RS-SRR-SS adjustable spatial motion generator is synthesized by analytical methods with two exact prescribed positions (including orientations) for each of two different motion tasks, by numerical methods to solve a nonlinear system of equations and by optimization techniques to minimize the motion errors at additional, approximately prescribed positions.
Efficient Optimization of Computationally Expensive Objective Functions
Authors: Karidis J. P. , Turns S. R.
Published: January 2010

An algorithm is presented for the efficient constrained or unconstrained minimization of computationally expensive objective functions. The method proceeds by creating and numerically optimizing a sequence of surrogate functions which are chosen to approximate the behavior of the unknown objective function in parameter-space. The Recursive Surrogate Optimization (RSO) technique is intended for design applications where the computational cost required to evaluate the objective function greatly exceeds both the cost of evaluating any domain constraints present and the cost associated with one iteration of a typical optimization routine. Efficient optimization is achieved by reducing the number of times that the objective function must be evaluated at the expense of additional complexity and computational cost associated with the optimization procedure itself. Comparisons of the RSO performance on eight widely used test problems to published performance data for other efficient techniques demonstrate the utility of the method.
Rotatability Considerations for Spherical Four-Bar Linkages With Applications to Robot Wrist Design
Authors: Gupta K. C.
Published: January 2010

The following result for spherical four-bar mechanisms is proved: Let all links of a spherical four-bar linkage be in the range [0, π]. Consider two linkages—one primary (p) and another secondary (s) according to the condition αip + αfp < αis + αfs where αs = π − αp. Then the input link is fully rotatable iff αip + αfp < αc + α0, |αip − αfp| > |αc − α0| and αip + αfp + αc + α0 < 2π. An alternate form of this result also is developed. Applications of these results in determining full or partial rotatability of grippers in spherical robot wrists are discussed.
Measurement of Torsional Vibration in Rotating Machinery
Authors: Vance J. M. , French R. S.
Published: January 2010

Five techniques for measurement of torsional vibration in a drive train are described, along with the advantages and disadvantages of each. Two laboratory test rigs, designed and constructed for experimental evaluation of various torsional vibration measurement techniques, are described. The measurement techniques investigated fall into three categories: a) those using signals from strain gages, b) those using signals from a magnetically transduced gear, and c) using signals optically transduced from a special tape applied to the shaft. One of the techniques described requires no specialized instrumentation other than a spectrum analyzer, which is now typically available in plants with rotating machinery. Another technique is capable of producing a detailed time history of torsional oscillations during acceleration of the drive train (i.e., startup), using a time interval measurement system. A comparison of results from the various techniques is given, and recommendations are made for several types of applications.
Instantaneous Properties of Multi-Degrees-of-Freedom Motions—Line Trajectories
Authors: Ghosal Ashitava , Roth Bernard
Published: January 2010

A general framework is presented for the study of the properties of trajectories generated by lines embedded in rigid bodies undergoing multi-degrees-of-freedom motions. Several new concepts, such as a line’s angular and linear velocities and accelerations, are introduced and used to (1) characterize the differences between line trajectories generated by different mechanisms; (2) distinguish trajectories generated by different lines in the same rigid body; (3) distinguish properties at different positions in the same trajectory. Line trajectories are classified according to the number of degrees of freedom of the motion, and local and global properties are discussed. These techniques are illustrated in an example of a line trajectory generated by a two-degrees-of-freedom manipulator.
Design Optimization of Machine-Tool Dynamics Based on Clarification of Competitive-Cooperative Relationships Between Characteristics
Authors: Yoshimura Masataka
Published: January 2010

This paper proposes a design optimization method of machine-tool dynamics based on clarification of competitive and cooperative relationships between characteristics. Clarification of competitive and cooperative relationships between characteristics results in division of design variables into three groups. The design variables of each group are determined in each of the three-phase design optimization procedures. The design decision problem in each procedure is far simpler and easier than that in usual design optimization methods, in which all design variables are determined at the same time. The competitive and cooperative relations between characteristics are first clarified. Next, algorithmic procedures of the design optimization method are constructed. The method is demonstrated on a structural model of a milling machine.
A Theory for the Articulation of Planar Robots: Part I—Kinematic Analysis for the Flexure and the Parallel Operation of Robots
Authors: Young L. , Duffy J.
Published: January 2010

This paper is the first of a series of papers developing a theory for the articulation of planar robots. Here, end effectors are considered to be moving on specified trajectories regardless of orientation, which is considered to be a free parameter, and which together with the remaining link orientations can be used to flex and hence articulate the arms to avoid interference. The theory is based on the geometry of the robots and workspace structures. An affine transformation is introduced for determining the relative location of pairs of links which are modeled by line segments.
Kinematic and Dynamic Analysis of Parallel Manipulators by Means of Motor Algebra
Authors: Sugimoto Koichi
Published: January 2010

The derivation of a kinematic and dynamic model for a parallel manipulator is presented in this paper. The model can be used to calculate displacements, velocities, and accelerations of both joints and links, and also joint torques and forces required to drive a manipulator. The expression in this paper, which is derived using the motor algebra and the Newton-Euler formulation, can be applied to many kinds of parallel manipulators.
Robot Workspace of a Tool Plane: Part 2—Computer Generation and Selected Design Conditions for Dexterity
Authors: Davidson J. K. , Pingali P.
Published: January 2010

In this paper the algorithm is completed for generation of envelope-surfaces for plane-workspaces of generally proportioned manipulators. Then the ruled surface Ψ is used for adapting the algorithm to 3-R manipulators for which the outermost two axes intersect (a2 = 0). The discriminant D is further developed, and it is used to classify 3-R manipulators, having a2 = 0, into seven Types. Manipulators, which are of Type 7, (i) can provide any orientation to a tool plane σ or (ii), with a fourth appropriately placed R joint and tool plane Σ, can also provide any attitude to the end effector. Design conditions are developed and presented which ensure that a manipulator will possess these properties of dexterity. The conditions are based on coupled motions at all three, or four, axes.
A Methodology for Synthesizing High-Performance Robots Fabricated With Optimally Tailored Composite Laminates
Authors: Sung C. K. , Thompson B. S.
Published: January 2010

An essential ingredient of the next generation of robotic manipulators will be high-strength lightweight arms which promise high-performance characteristics. Currently, a design methodology for optimally synthesizing these essential robotic components does not exist. Herein, an approach is developed for addressing this void in the technology-base by integrating state-of-the-art techniques in both the science of composite materials and also the science of flexible robotic systems. This approach is based on the proposition that optimal performance can be achieved by fabricating robot arms with optimal cross-sectional geometries fabricated with optimally tailored composite laminates. A methodology is developed herein which synthesizes the manufacturing specification for laminates which are specifically tailored for robotic applications in which both high-strength, high-stiffness robot arms are required which also possess high material damping. The parameters in the manufacturing specification include the fiber-volume fraction, the matrix properties, the fiber properties, the ply layups, the stacking sequence and the ply thicknesses. This capability is then integrated within a finite-element methodology for analyzing the dynamic response of flexible robots. An illustrative example demonstrates the approach by simulating the three-dimensional elastodynamic response of a robot subjected to a prescribed spatial maneuver.
The Instantaneous Kinematics of Line Trajectories in Terms of a Kinematic Mapping of Spatial Rigid Motion
Authors: McCarthy J. M.
Published: January 2010

The dual Euler parameters of a rigid spatial motion are used to define a curve on a dual unit hypersphere. The dual velocity, curvature, and torsion of this curve form a set of instantaneous parameters related to the instantaneous invariants of the motion. In this paper these new parameters are used to reformulate the kinematic theory of line trajectories. The distribution parameter, Disteli formulas, and the inflection congruence are examined in detail.
A Compliance Number Concept for Compliant Mechanisms, and Type Synthesis
Authors: Her I. , Midha A.
Published: January 2010

While much has been contributed to techniques for enumerating and identifying rigid-body mechanisms in the past decades, proportionally little has been accomplished in this regard in compliant mechanisms design. This paper deals primarily with identification and discussion of important kinematic properties of compliant mechanisms. To facilitate these appropriate terminology is developed at the very fundamental level. The conventional degrees-of-freedom concept for a rigid-body chain is briefly reviewed. It is then used to help define a compliance number (or degrees-of-compliance) concept for characterizing compliant mechanisms. Finally, a systematic and convenient approach is presented, enabling the type synthesis of this class of mechanisms.
Computer Aided Concept Design for Structural Configuration of Machine Tools: Variant Design Using Directed Graph
Authors: Shinno H. , Ito Y.
Published: January 2010

The modular design system has recently become important, not only to rationalize the design and manufacturing procedures of the machine tool, but also to evolve the flexible manufacturing system. In this paper, therefore, to establish a design methodology for the modular construction system of machine tools, a generating method for structural configuration, i.e., a procedure of computer aided concept design has been proposed. The proposed method is of variant design type, in which a machine tool as a whole and modular complex are represented with the directed graph, it being suitable for the information processing and storage of data. When generating a structural configuration, at first, possible modular complexes in the data memory are referred to, and then through simple mathematical treatment they are integrated so as to form structural configurations. By this method, all possible structural configurations of the machine tool can be generated systematically and rationally, according to the machining requirement.
Implementation of Design Sensitivity Analysis with Existing Finite Element Codes
Authors: Choi K. K. , Santos J. L. T. , Frederick M. C.
Published: January 2010

A numerical method is presented to implement structural design sensitivity analysis theory, using the versatility and convenience of existing finite element structural analysis programs. Design variables such as thickness and cross-sectional areas of components of individual members and built-up structures are considered. Structural performance functionals considered include displacement and stress. The method is also applicable for eigenvalue problem design sensitivity analysis. It is shown that calculations can be carried out outside existing finite element codes, using postprocessing data only. Thus design sensitivity analysis software does not have to be imbedded in an existing finite element code. Feasibility of the method is shown through analysis of several problems, including a built-up structure. Accurate design sensitivity results are obtained without the uncertainty of numerical accuracy associated with selection of finite difference perturbations.
Triad Synthesis for up to Five Design Positions With Application to the Design of Arbitrary Planar Mechanisms
Authors: Chase T. R. , Erdman A. G. , Riley D. R.
Published: January 2010

A new synthesis tool, the triad, is introduced to enable simplified synthesis of very complex planar mechanisms. The triad is a connected string of three vectors representing jointed rigid links of an actual mechanism. The triad is used as a tool to model an original mechanism topology with a set of simpler components. Each triad is then used to generate a set of “relative precision positions” which, in turn, enables the dimensional synthesis of each triad with well-established motion and path generation techniques for simple four-bar linkages. Two independent derivations of the relative precision positions are provided. All common triad geometries amenable to simple dyad synthesis techniques are presented. The triad geometries summarized here may be applied to two, three, four, and five precision position problems using graphical, algebraic, or complex number formulations of Burmester theory. Examples are provided.
A Method for Determining the Various Gear Trains that Provide a Specific Velocity Ratio
Authors: Arabyan A. , Shiflett G. R.
Published: January 2010

The problem of determining the number of teeth on a set of meshing gears for the creation of a gear train is examined. A method is proposed for determining all the gear trains which yield identical velocity ratios and an algorithmic description of the method is provided. Several examples are included in which the results are compared to those of other methods.
Complete Dynamic Analysis of Elastic Linkages
Authors: Dado M. , Soni A. H.
Published: January 2010

A complete dynamic analysis procedure to analyze elastic linkages is presented in this study. Forward and inverse dynamics techniques are developed for elastic linkages with revolute and prismatic pairs. The techniques utilize finite-line-element method in solving for the elastic displacements and system internal forces. The analysis procedure is applicable to multiloop and multidegree-of-freedom systems. The driving forces and torques may be functions of time, displacement, and/or velocity. In forward dynamic analysis, an integration procedure is developed to evaluate the system coordinate velocities and displacements. Numerical examples are presented to illustrate the analysis techniques and their features.
Lateral Stability Behavior of Railway Freight Car System With Elasto-Damper Coupled Wheelset: Part 2—Truck Model
Authors: Ahmed A. K. W. , Sankar S.
Published: January 2010

To investigate the effect of elasto-damper coupled wheelset (EDCW), on the lateral stability behavior of freight cars, a railway freight truck model with two EDCW and pseudo-car body has been developed. The results of linearized stability analysis showed, that for small values of wheelset coupler stiffness, damping has significant influence on the stability behavior of wheelset relative spin as well as wheelset and truck lateral modes. The results further showed that, by utilizing an optimal EDCW coupler parameter, the critical speeds corresponding to truck hunting and wheelset lateral mode can be made equal. In doing so, the truck hunting critical speed on tangent track can be improved by over 100 percent in comparison to truck model with conventional rigid axle wheelsets.
Modeling of a Mid-Size Passenger Car Using a Multibody Dynamics Program
Authors: Trom J. D. , Lopez J. L. , Vanderploeg M. J.
Published: January 2010

This paper presents a multibody model of a passenger car and correlates the model with experimental data. Included in the model is a simple load-leveling control algorithm for controlling low frequency roll and pitch. The objectives of this paper are: to evaluate the effectiveness of vehicle modeling using a multibody dynamics program; to demonstrate multibody modeling techniques for complex suspension systems without the use of bushing models; and to demonstrate the feasibility of implementing control algorithms in multibody dynamics programs. The paper concludes that using multibody dynamics programs can be an effective method to model ride, handling, and braking of wheeled vehicles. The model presented in this paper shows good correlation in both the linear and nonlinear ranges for most maneuvers.
Optimal Design of Bourdon Gage Mechanisms
Authors: Beiner L.
Published: January 2010

The paper deals with the optimization of lever-segment gear-pinion mechanisms used in the construction of Bourdon gage manometers. The number of teeth of the pinion (which is rigidly attached to the manometer hand) is used as an objective function in order to maximize accuracy. Design variables are the gear-pinion center distance and center line inclination and various constraints are imposed in order to satisfy operating conditions and constructive limits. An example is presented showing that the objective function is maximized by the highest feasible value of the center distance and is less sensitive to variations of the center line inclination.
Workspace Analysis of 4R Manipulators With Various Degrees of Dexterity
Authors: Rastegar J.
Published: January 2010

For 4R manipulators and their various possible configurations, workspaces with full, partial, and zero dexterity are defined, and a procedure to determine them is developed. As examples, two 4R manipulators are analyzed. Subspaces with 2, 4, 6, and 8 configurations and various degrees of dexterity are found. Several points on the effect of geometrical parameters on the shape and extent of the boundary surfaces, subspaces, and number of configurations are discussed. An index for the evaluation of the degree of accessibility of the workspace of a manipulator is also proposed.
Belt Forces and Surface Model for a Cloth-Backed and a Rubber-Backed Flat Belt
Authors: Kim H. , Marshek K. M.
Published: January 2010

The normal and tangential belt forces for two types of flat belts are measured and compared. From friction theory, it was assumed that the actual contact area Aa is proportional to normal pressure p; i.e., Aaαpn. For a flat belt with cloth backing, the n =2/3 is obtained for the belt surface contact model. For a flat belt with rubber backing, which is used for power transmission, the n = 0.9 to 1.0 is suggested as a surface model. Different friction surfaces, construction materials, and geometries for the two belts resulted in different contact patterns and different friction characteristics.
A Modified Design for λ-Type Double-Cranks to Approximate a Straight Line
Authors: Dijksman E. A.
Published: January 2010

Double-cranks containing a Chebyshev-dyad are investigated for their use as a straight-line mechanism. The three available design degrees of freedom have been used for the optimization of the minimum transmission angle, for the minimization of the maximum deviation and for the length L of the straight-stretch in the coupler curve. The resulting double-cranks are shown to have deviations that are about half as large as for those in which the coupler point lies on the extension of the coupler. For any maximum deviation, the length L of the straight-stretch also appears to be about 1.5 times as long as the one obtained when Ball’s point lies at the base of the design. A graph showing the maximum deviation as a function of L allows the designer to pick his choice mechanism. A table also will be of help to find accurate dimensions of the mechanism that yields a given deviation or a given length L of the straight part in the coupler curve.
The Optimal Design of a Rotary Type Actuator for Magnetic Disk Drives
Authors: Robertson W. D. , Gabriele G. A.
Published: January 2010

One of the most important assemblies in any computer disk drive is the actuator which positions the read/write coil over the disk. Historically, actuators have been of the linear type, but in recent years the rotary actuator has become more popular because of its lower inertia and higher reliability. In this paper we describe the optimization of the rotary actuator geometry to achieve a minimum seek time. An objective function which approximates seek-time is derived based on the polar moment of inertia and the sweep of the actuator. A set of constraints is also developed which control mechanical resonances, skew angles, and physical position of the actuator. An optimal solution is presented as well as a sensitivity study of the final design. It is shown that the final design is relatively insensitive to changes in the problem parameters. Additionally, the sensitivity analysis reveals that a static balance constraint which is originally ignored, is not necessary.
A Combined Local-Global Active Set Strategy for Nonlinear Design Optimization
Authors: Li Heng Long , Papalambros P. Y.
Published: January 2010

Local and global knowledge in rule-based forms is combined in an active set strategy for nonlinear programming design models. The combined strategy is implemented with a reduced gradient algorithm for solution of the equality constrained sub-problem. The strategy unifies previously separate local and global strategies. Algorithmic implementation and performance are discussed together with examples. This article is a sequel to a previous one describing a linear programming application of the strategy.
A General Method for Computing Worm Gear Conjugate Mesh Property: Part 1—The Generating Surface
Authors: Zheng Changqi , Lei Jirong , Savage Michael
Published: January 2010

This article is a two-part one: (1) the generating surface; (2) the mathematic model of the worm gear tooth surface. In this paper, a general method is presented for the description of generating surface enveloping any kind of worm tooth surface. This method is laid on the parametric description of the dresser curve as an initial curve. The initial curves of four common dressers are presented. By using these descriptions, the mathematical description and properties of any kind of worm gear tooth surface can also be obtained.
Modeling the Vibration of Systems Whose Configuration Can Vary
Authors: Garcia-Reynoso A. , Seering W. P.
Published: January 2010

A method is developed for predicting vibration-response characteristics of systems whose configuration changes during operation. A cartesian robot, an example of such a position-dependent system, served as a test case and was studied in detail. The chosen system model was formulated using the technique of Component Mode Synthesis (CMS). The model assumes that the system is slowly varying, and connects the carriages to each other and to the robot structure at the slowly varying connection points. Specific problems addressed in this paper include modeling of continually varying points of connection between components and selection of boundary conditions to represent overconstrained component boundaries. A method for curve-fitting modal data is also presented.
A Survey of One Class of 7-Jointed Serially Connected Robots: Type-Synthesis to Obtain Controllably Dexterous Workspace
Authors: Davidson J. K.
Published: January 2010

A type-synthesis process, which is based on screw theory and geometry, is developed to identify certain robots, each of which can provide controllably dexterous workspace of a tool-point. The identification process is confined to only those robots which control the motion of the end-effector with seven series-connected joints, the axes for the outermost three of which are concurrent. Forty six types of robots are so identified, and, for each, the results are (i) a suitable kinematic chain for the arm and (ii) suitable angle-dimensions for the links of the arm, where the angle-choices are limited to the values 0, ± π/2, and π. A geometric description of the dominant function for control is included. The same kinematic chains are surveyed for all possible parallel and right-angle arrangements of adjacent axes in the four links of the arm. Again utilizing screw theory, 160 robots are identified which do not posses full-cycle axis-dependence among some or all of the first five axes.
Design Conditions for the Orientation and Attitude of a Robot Tool Carried by a 3-R Spherical Wrist
Authors: Trabia M. , Davidson J. K.
Published: January 2010

The orientational (directional) and attitudinal capabilities for a generally-dimensioned 3-R spherical robot-wrist are presented. The wrist is treated both with joints which can freely rotate and with joints which encounter limits to rotation. A principal method is to consider a hypothetical tool-plane to be associated with the tool and to use the locus of this plane as a measure of tool orientation. Design conditions are developed and presented, among wrist dimensions and limits to rotation at the actuators, which permit a tool to be placed in any direction by the robot. A different range of directions is also established, for each of which the wrist is able to rotate the end-effector a full turn about an axis in that direction. These results contain all the attitudinal possibilities for the end-effector and are presented separately for a wrist (i) which is operated only in one closure, and (ii) which can be operated in both closures to provide a combined range of attitudes. The results are summarized in five tables.
The Mechanics and Positioning of Highly Flexible Manipulator Limbs
Authors: Wilson J. F. , Mahajan U.
Published: January 2010

This paper deals with the analysis of lightweight, flexible robotic limbs. A typical limb is a series of polymeric tube elements. One end is fixed and the payload at the other end is manipulated by varying the internal pressure in each element. The theoretical derivations relating limb position and its payload incorporate the nonlinear elastic properties of the element material and large deflections. A computer program stores information about limb position and after each successive limb manipulation the program adaptively upgrades itself to improve positioning accuracy. Results are illustrated with a numerical example.
Tooth Contact Analysis for Helical Gears with Pinion Circular Arc Teeth and Gear Involute Shaped Teeth
Authors: Tsay C.-B. , Fong Z. H.
Published: January 2010

In this paper, the theory of gearing and the concept of differential geometry have been applied to deal with the relations of two mating gears and of their bearing contact. The gear tooth surfaces of this type of gearing contact with each other at every instant at one point instead of one line. The bearing contact of the gear tooth surface is localized and the center of the bearing contact moves along the tooth surface. Thus, this type of helical gearing is not as sensitive to center distance variation and gear axes misalignment. This paper covered the solutions to the following problems: (1) Computer simulation of the conditions of meshing and bearing contact and (2) Investigation of the sensitivity of gears to the errors of manufacturing and assembly. A method of compensation for the dislocation of the bearing contact induced by errors of manufacturing and assembly has been proposed. Five numerical examples have also been presented to illustrate the influence of the above mentioned errors and the method of compensation for the dislocation of bearing contact.
Electro-Rheological-Fluid-Based Articulating Robotic Systems
Authors: Gandhi M. V. , Thompson B. S. , Choi S. B. , Shakir S.
Published: January 2010

The limitations of the current generation of robotic systems has triggered a new research thrust for predicting the elastodynamic response of assemblages of articulating flexible-bodied systems. This research thrust is extended herein by proposing the fabrication of robotic systems in either monolithic or ultra-advanced composite laminated high-strength, high-stiffness materials in which are incorporated electro-rheological fluids. These multiphase fluid systems, which change their rheological behavior instantaneously when subjected to an externally applied electrical field, provide a potential for tailoring the vibrational characteristics of these hybrid materials from which the structural members of the proposed robotic systems are fabricated. This paper is focused on developing the necessary design tools for predicting the vibrational response of flexible multibodied articulating systems fabricated with this new class of advanced materials. A variational theorem is developed herein as a basis for finite element formulations which can be employed to predict the elastodynamic response of these systems. A coherent combination of experimental and theoretical work on cantilevered beams is presented to demonstrate the viability of the proposed design methodology. In addition, computer simulation results are presented to demonstrate the potential payoffs in terms of superior performance characteristics of a new generation of robotic systems capitalizing on this innovative and revolutionary design philosophy.
A Framework for Algorithms in Globally Optimal Design
Authors: Hansen P. , Jaumard B. , Lu S. H.
Published: January 2010

Many problems of globally optimal design have been solved in the literature using monotonicity analysis and a variety of tests, often applied in an ad hoc way. These tests are developed here, expressed mathematically and classified according to the conclusions they yield. Moreover, many new tests, similar to those used in combinatorial optimization, are presented. Finally, a general framework is proposed in which branch-and-bound algorithms for globally optimal design problems can be expressed.
A Reconsideration of the Geometry Factor for the Standard and Profile Shifted Teeth
Authors: Kuang J. H. , Yang Y. T.
Published: January 2010

A semi-empirical equation for the determination of the stress concentration factor for spur gears is introduced. The effects of some design parameters such as fillet radii of rack cutters, teeth number, and profile shifting factor, on the stress distribution at the fillets of gear teeth are investigated. Values of the modified geometry factors for the standard and profile shifted teeth are also derived. It is hoped that the present investigation may yield a more accurate prediction of the localized stresses at tooth fillets than the results thus far available.
A Generalized Expert System Shell for Implementing Mechanical Design Applications: Review, Introduction, and Fundamental Concepts
Authors: Premkumar P. , Kramer S.
Published: January 2010

The foundations for an expert system shell for implementing mechanical design applications are presented in this paper. The shell supports facilities for knowledge acquisition, quasi-reactive planning, design evaluation, and subjective explanation. The underlying philosophy of each of these facilities and some preliminary implementation issues are discussed. A brief summary of a recent research effort and its implications on the development of a generalized expert system shell for implementing mechanical design applications are also presented.
Analysis of Spatial Open-Loop System by Means of Direction Cosine Transformation Matrices
Authors: Yih T. C. , Youm Y.
Published: January 2010

In this paper, an analytical approach for the displacement analysis of spatial openloop systems by means of direction cosine transformation matrices is presented. Two local coordinate systems at each joint are designated to formulate the direction cosine matrices, in recursive form, of the joint axis and link vector. Elements of the 3×3 direction cosine transformation matrices are computed based on the geometry of successive link elements, the unit vectors of preceding joint axis and link vector, and the cofactors of direction cosine matrix. The analysis using direction cosine matrix method will provide the “exact” joint positions in space. A computer algorithm is developed to investigate the workspaces of spatial n-R open-loop systems that projected onto the X-Y, Y-Z, and Z-X coordinate planes, respectively. Numerical examples for the workspaces of an industrial robot and the human upper extremity are illustrated.
Identification and Observability Measure of a Basis Set of Error Parameters in Robot Calibration
Authors: Menq Chia-Hsiang , Borm Jin-Hwan , Lai Jim Z.
Published: January 2010

This paper presents a method of identifying a basis set of error parameters in robot calibration using the Singular Value Decomposition (SVD) method. With the method, the error parameter space can be separated into two: observable subspace and unobservable one. As a result, for a defined position error model, one can determine the dimension of the observable subspace, which is vital to the estimation of error parameters. The second objective of this paper is to study, when unmodeled error exists, the implications of measurement configurations in robot calibration. For selecting measurement configurations in calibration, and index is defined to measure the observability of the error parameters with respect to a set of robot configurations. As the observability index increases, the attribution of the position errors to the parameters becomes dominant and the effects of the measurement and unmodeled errors become less significant; consequently better estimation of the parameter errors can be obtained.
Automated Modeling and Rapid Solution of Robot Dynamics Using the Symbolic Polynomial Technique
Authors: Townsend M. A. , Gupta S.
Published: January 2010

Fast and accurate solutions of the dynamic equations of a robot arm are required for real time on-line control. In this paper we present a new method for rapidly evaluating the exact dynamic state of a robot. This method uses a combination of symbolic and numerical computations on the equations of motion, which are developed in the form of polynomials—hence the name, the symbolic polynomial technique.
Optimum Synthesis of Thin-Walled Vibrating Beams With Coupled Bending and Torsion
Authors: Grandhi R. V. , Moradmand J. K.
Published: January 2010

This paper considers the optimum structural design of vibrating beams in which the inertial axes and the elastic axes are noncollinear. The condition of noncollinear axes exists in structures having unsymmetric cross-sections. For unsymmetric cross-sections the centroid and the shear center do not coincide. This results in coupling between some of the bending and torsional modes. This paper presents results for the simply supported and cantilever beams with a thin-walled channel cross-section. The minimization of the structural volume subject to multiple frequency constraints and its dual problem of maximization of the fundamental frequency subject to a volume constraint are considered. A quadratic extended interior penalty function with Newton’s method of unconstrained minimization is used in structural optimization. The structures considered have nonstructural masses besides their own mass.
Comparison of the Dynamics of Conventional and Worm-Gear Differentials
Authors: Freeman J. S. , Velinsky S. A.
Published: January 2010

The differential mechanism has been used for many years and a variety of unique designs have been developed for particular applications. This paper investigates the performance of both the conventional bevel-gear differential and the worm-gear differential as used in vehicles. The worm-gear differential is a design in which the bevel gears of the conventional differential are replaced by worm gear/worm wheel pairs. The resultant differential exhibits some interesting behavior which has made this differential desirable for use in high performance and off-road vehicles. In this work, an Euler-Lagrange formulation of the equations of motion of the conventional and worm-gear differentials allows comparison of their respective behavior. Additionally, each differential is incorporated into a full vehicle model to observe their effects on gross vehicle response. The worm-gear differential is shown to exhibit the desirable characteristics of a limited-slip differential while maintaining the conventional differential’s ability to differentiate output shaft speeds at all power levels.
Optimal Tooth Modifications for Spur and Helical Gears
Authors: Simon V.
Published: January 2010

A method for the simultaneous calculation of optimal tooth tip relief and tooth crowning for spur and helical gears is presented in this paper. The tooth profile modification is described by a linear function. Two types of crowning are introduced: linear and parabolic. The optimization of the tooth modifications is based on the following conditions: (1) The teeth are entering in mesh smoothly, without interference. (2) The load distribution factor is minimized. A computer program is developed for the calculation of the optimal tooth tip relief and crowning for spur and helical gears. By using this program the influence of type and length of optimal crowning and length of tooth tip relief on load distribution factor is investigated. Also, the influence of gear parameters on optimal tooth profile modification is discussed. On the basis of the obtained results, by regression analysis an equation is derived for the calculation of the optimal tooth tip relief.
Dynamic Analysis of Elastic Beam-Like Mechanism Systems
Authors: Ying W. , Huston R. L.
Published: January 2010

In this paper the dynamic behavior of beam-like mechanism systems is investigated. The elastic beam is modeled by finite rigid segments connected by joint springs and dampers. The equations of motion are derived using Kane’s equations. The nonlinear terms are linearized by first order perturbation about a system balanced configuration state leading to geometric stiffness matrices. A simple numerical example of a rotating cantilever beam is presented.
Finite Element Mesh Generation of Planar Surfaces Using an Interactive Node Point Placement Technique
Authors: Rusnock P. S. , Cipra R. J.
Published: January 2010

A method is presented for interactively generating finite element meshes for two-dimensional surfaces. The technique is implemented on a graphics display device and will allow the user to create and alter finite element meshes. Given the object shape, the nodes comprising the mesh automatically distribute themselves over the surface as a result of their interaction with neighboring particles and the boundary. They seek equipotential locations, which can be further modified interactively by the user. Based upon these nodal locations, triangular or quadrilateral elements are generated automatically.
Numerical Considerations in Structural Component Shape Optimization
Authors: Yang R. J. , Choi K. K. , Haug E. J.
Published: January 2010

A unified design sensitivity analysis theory and a linearization method of optimization are employed for structural component shape optimization. A material derivative method for shape design sensitivity analysis, using the variational formulation of the equations of elasticity and the finite element method for numerical analysis, is used to calculate derivatives of stress and other structural response measures with respect to boundary shape. Alternate methods of boundary shape parameterization are investigated, through solution of two test problems that have been treated previously by other methods: a fillet and a torque arm. Numerical experiments with these examples and a variety of finite element models show that component shape optimization requires careful selection of boundary parameterization, finite element model, and finite element grid refinement techniques.