bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Motion Characteristics of Tripode Joints. Part 2: Applications
Authors: Lee T. W. , Akbil E.
Published: January 2010

The theory developed in Part 1 has been applied to the determination of motion characteristics of two typical types of shaft couplings involving tripode joints. An ideal case of an exact constant-velocity coupling is first described and analyzed. The remainder of the paper focuses on a practical shaft coupling of the tripode-Rzeppa combination which is widely used in front-wheel drive vehicles. The results demonstrate that the displacement equation of this combination is a fourth-order polynomial in the tangent of the output crank angle, and this coupling does not provide a true constant-velocity joint, but rather an approximate one. Parameters affecting the velocity fluctuation and their influences are presented. In addition, it is found that there exists a definite phase lag of thirty degrees between the displacement and velocity curves at all times on the output shaft. Whenever possible, numerical results for the motion characteristics of the joint and its components are illustrated by computer-plotted graphs, which may also offer some insight into the behavior of the tripode joint.
Special Cases of Friction and Applications
Authors: Litvin F. L. , Coy J. J.
Published: January 2010

Two techniques for reducing friction forces are presented. The techniques are applied to the generalized problem of reducing the friction between kinematic pairs which connect a movable link to a frame. The basic principles are: (a) Let the movable link be supported by two bearings where the relative velocities of the link with respect to each bearing are of opposite directions. Thus the resultant force (torque) of friction acting on the link due to the bearings is approximately zero. Then, additional perturbation of motion parallel to the main motion of the movable link will require only a very small force. (b) Let the perturbation in motion be perpendicular to the main motion. Equations are developed which explain these two methods. The results are discussed in relation to friction in geared couplings, gyroscope gimbal bearings, and a rotary conveyer system. Design examples are presented.
Assembly Integrity of Coaxial Rigid Parts Positioned by Congruent Conical Pilots. Part 1: R-R End Conditions
Authors: Davidson J. K. , Ferrel R. S.
Published: January 2010

Congruent conical pilots can be used to configure the contacting surfaces of coaxially assembled rigid cylindrical parts where assembly integrity is obtained by an axial clamping load and where externally applied constraints occur only at the ends of the assembly. The relative motion for mating parts is developed for parts of arbitrary length. A method for optimal geometric design of the pilots is presented for the special conditions that all the parts be of the same length and that the assembly contain the minimum number of parts permissible for instability to occur. Application of the optimal design method achieves the maximum stability in the presence of a lateral destabilizing load. For each part dimension, the optimal value is at a domain limit.
Tooth Load Sharing in High-Contact Ratio Spur Gears
Authors: Elkholy A. H.
Published: January 2010

A closed-form solution is presented for calculating the load sharing among meshing teeth in high contact ratio gearing (HCRG). The procedure is based upon the assumption that the sum of the tooth deflection, profile modification and spacing error at each of two or three pairs of contacts are all equal. It is also assumed that the sum of the normal loads contributed by each of two or three pairs of contacts is equal to the maximum normal load. Once the individual loads are determined, the tooth fillet stress, contact stress may be determined from the applied load and tooth geometry. An experimental example appears to verify the method.
Heat Generation in Thermoplastic Spur Gears
Authors: Koffi D. , Gauvin R. , Yelle H.
Published: January 2010

Since thermoplastics are temperature-sensitive materials, heat generation in running spur gears is an important parameter. This paper presents two models for its evaluation, an exact one which considers all the parameters but needs a computer to solve the equations; then a simplified model. Both models take into account the contact outside the theoretical line of action which is the usual case with thermoplastic gears. Results for the simplified model are within reasonable agreement with the exact one.
On the Mechanical Efficiency of Differential Gearing
Authors: Yu D. , Beachley N.
Published: January 2010

Although much work has been done on the efficiency of epicyclic gearing, emphasis has usually been given to the planetary that has only one degree of freedom. In this paper, a thorough study of the efficiency of differential gearing that has two degrees of freedom is presented. New analytical methods and programs are designed to calculate differential efficiencies and to plot useful curves. Examples are given for split-path differential, continuously variable transmissions (CVT) with input power coupling. It is pointed out that there are six different ways of using a given differential design in such a split-path CVT, providing the opportunity for full utilization of its potential. With the help of computer programming, optimum designs can be obtained.
Power Transmission Efficiencies and Friction Coefficients at Teeth of Novikov-Wildhaber and Involute Gears
Authors: Ishibashi A. , Yoshino H.
Published: January 2010

New equations have been derived to calculate the power transmission efficiencies, at the meshing teeth, of two kinds of representative cylindrical gears, Novikov-Wildhaber and involute gears. The efficiencies could be calculated from the equations and the friction coefficients obtained by simple experiments with test rollers. In order to show clearly the difference in the power transmission efficiencies of the two kinds of gears, the authors designed and made two interesting gear pairs with a small number of pinion teeth (Z1 = 3) and with a high gear ratio (Z2/Z1 = 9) by applying new techniques developed by them. The effects of gear speed, tooth load, type of lubricant, etc. upon the power transmission efficiencies were clarified using two interesting techniques to measure the efficiency. The experimental results indicated that the efficiency of the Novikov-Wildhaber gears was appreciably higher at high speeds, while it was lower than the involute gears at the start of rotation and also at low speeds.
Instantaneous Kinematics of Three-Parameter Motions
Authors: Pennock G. R. , Yang A. T.
Published: January 2010

In this paper we study the instantaneous kinematics of a three-link open-chain system. We derive concise closed-form expressions to determine the angular velocity, the pitch, and the instantaneous screw axis that describe the three-parameter motion of the terminal link of the three-link chain relative to the fixed base. Using two joint angular velocity ratios as variable parameters we interpret the double-infinity of solutions as a family of cylindroids. For illustrative purposes, we present an analysis of the arm subassembly of two well-known robot manipulators.
Application of Dual-Number Matrices to the Inverse Kinematics Problem of Robot Manipulators
Authors: Pennock G. R. , Yang A. T.
Published: January 2010

This paper presents the application of dual-number matrices to the formulation of displacement equations of robot manipulators with completely general geometry. Dual-number matrices make possible a concise representation of link proportions and joint parameters; together with the orthogonality properties of the matrices we are able to derive, in a systematic manner, closed-form solutions for the joint displacements of robot manipulators with special geometry as illustrated by three examples. It is hoped that the method presented here will provide a meaningful alternative to existing methods for formulating the inverse kinematics problem of robot manipulators.
Closed and Expanded Form of Manipulator Dynamics Using Lagrangian Approach
Authors: Wang T. , Kohli D.
Published: January 2010

An alternative derivation of the equations of motion of a chain of rigid bodies using Lagrangian equations of motion is presented. In an effort to reduce the complexity of the coefficients appearing in the equations of motion, a modified form of Lagrangian equations due to Silver [3] are utilized. This approach leads to a simplified form of coefficients of the equation of motion.
A Study of the Jacobian Matrix of Serial Manipulators
Authors: Waldron K. J. , Wang Shih-Liang , Bolin S. J.
Published: January 2010

Inversion of the Jacobian matrix is the critical step in rate decomposition which is used to solve the so-called “inverse kinematics” problem of robotics. This is the problem of achieving a coordinated motion relative to the fixed reference frame. In this paper a general methodology is presented for formulation and manipulation of the Jacobian matrix. The formulation is closely tied to the geometry of the system and lends itself to simplification using appropriate coordinate transformations. This is of great importance since it gives a systematic approach to the derivation of efficient, analytical inverses. The method is also applied to the examination of geometrically singular positions. Several important general results relating to the structure of the singularity field are deducible from the structure of the algebraic system.
Programming Optimal Suggestions in the Design Concept Phase: Application to the Boothroyd Assembly Charts
Authors: Jakiela M. , Papalambros P. , Ulsoy A. G.
Published: January 2010

Traditional creativity-enhancement ideas and modern data handling by computing machines can be merged to create programs that make optimal suggestions to the designer. These suggestions are most useful during the design concept phase where a synthesis is attempted. The appropriate structuring of such programs is generally data- or problem-specific. From the study of specific applications general rules may emerge. This article demonstrates that approach with an application to the data contained in charts proposed by Boothroyd as guides to design for assembly.
On Analytical Evaluation of Gear Dynamic Factors Based on Rigid Body Dynamics
Authors: Wang C. C.
Published: January 2010

This paper proposes an initial step to rationalize the dynamic factor calculation and bring it under the control of the laws of mechanics. The theory is straight forward. The concept of mathematical scaling is utilized to simplify the system dynamics’ formulation. The rigid body dynamics accounts for the gear dynamic tooth loads resulting from the prescribed transmission error of each gear step—including the artificial ones. The latter converts a lumped-mass-elastic system into a rigid-bodies-transmission-error system subjected to the solution of the rigid body system dynamics according to Newton’s law. The entire concept of the solution has been implemented into a FORTRAN program approximately 600 statements in length. The results obtained through computer simulation of various test cases demonstrate the potential and effectiveness of the proposed concept. Contrary to the current practice of grossly ignoring the inertial and system effects, this paper has taken all these important factors into account. The transmission-error-induced acceleration is approximated by the second-order time derivative of one of the cubic spline curve-fitting methods. The approach is cost effective and numerically satisfactory. The model can be further improved to reduce the extent of basic assumptions, or to increase the number of conditional constraints without losing economical attractiveness.
Simulated On-Line Process Optimization of a Robotic Materials Handling System
Authors: King M. S. , Blundell J. K.
Published: January 2010

Industrial robots in use today lack the total ability to perceive and interact with their environment. This limitation is a major obstacle confronting robotic systems developers. This work outlines an on-line process optimization strategy which allows a robot to work within a time-varying environment. After developing the kinematic model of the robot and its relationship to its environment, the process optimization strategy is simulated. The performance of the system is measured by using an index of performance and comparing the simulation results against a series of non-optimized models. The results indicate that on-line process optimization strategy significantly increases the performance of a robotic system operating in a time-varying environment.
A Maximal Activity Principle for Eliminating Overconstrained Optimization Cases
Authors: Wilde D. J.
Published: January 2010

In searching for an optimum by examining assignments of active constraints, one wishes to avoid assignments with no solution. A simple Maximal Activity Principle is stated to detect situations in which some subset of constraints has too few variables. The principle is illustrated on a well-known weldment design problem.
Dynamics of Flexible Mechanical Systems Using Vibration and Static Correction Modes
Authors: Yoo W. S. , Haug E. J.
Published: January 2010

A finite-element-based method is developed and applied for geometrically nonlinear dynamic analysis of spatial mechanical systems. Vibration and static correction modes are used to account for linear elastic deformation of components. Boundary conditions for vibration and static correction mode analysis are defined by kinematic constraints between components of a system. Constraint equations between flexible bodies are derived and a Lagrange multiplier formulation is used to generate the coupled large displacement-small deformation equations of motion. A standard, lumped mass finite-element structural analysis code is used to generate deformation modes and deformable body mass and stiffness information. An intermediate-processor is used to calculate time-independent terms in the equations of motion and to generate input data for a large-scale dynamic analysis code that includes coupled effects of geometric nonlinearity and elastic deformation. Two examples are presented and the effects of deformation mode selection on dynamic prediction are analyzed.
Irregular Geneva-Wheel and Geneva-Slider Mechanisms for the Generation of Nonuniform Index Ratios During a Cycle
Authors: Bagci Cemil
Published: January 2010

The article deals with Geneva mechanisms driven with multiple cranks for the generation of multiple indexings with different index ratios during a cycle of motion. Both, Geneva-wheel mechanisms, and Geneva-slider mechanisms for the generation of rotary and linear motions with dwells, respectively, are considered. Design equations for both types of Geneva mechanisms are offered to synthesize the motion and dwell-time distributions, or the index ratio distributions, during a cycle of motion, and synthesize for the dimensions of the system. Partially irregular and completely irregular Geneva mechanisms are considered for both types, where the partially irregular Geneva mechanisms generate the same motion time but different dwell times for different indexings, while the completely irregular Geneva mechanisms generate different motion times as well as different dwell times for different indexings during a sequence of indexings. Sequences of indexings during one cycle of motion (during one rotation of the Geneva wheel, for example) can be repeated several times. The uses of the design equations offered are illustrated with six industrial application examples.
Multistage Multiobjective Optimization of Gearboxes
Authors: Rao S. S. , Eslampour H. R.
Published: January 2010

The problems of kinematic and strength designs of multispeed gearboxes are formulated as multiobjective optimization problems. In the kinematic design stage, the speeds of all the shafts, the number of teeth on various gears and the gear module are selected so as to minimize the deviation of output speeds from specified values and the overall center distance of the gearbox. In the strength design stage, the face widths of the various gear pairs are chosen so as to minimize the volume of the material of the gears and to maximize the power transmitted by the gearbox. A goal programming approach is suggested for the solution of the multiobjective nonlinear constrained optimization problem by treating the ideal feasible solutions as the goals for the corresponding objective functions. The utility of the resulting computer program is demonstrated through the design of six- and 18-speed gearboxes. The present methodology offers the feasibility of automating the design of gearboxes by incorporating all the (conflicting) design requirements and objectives.
Singularities in Motion and Displacement Functions of Spatial Linkages
Authors: Litvin F. L. , Fanghella P. , Tan Jie , Zhang Yi
Published: January 2010

A new approach for the determination of singularities and displacement functions of spatial linkages is proposed. Singularities in motion occur at positions where an overconstrained group of links becomes movable while the driving link is fixed. Two alternative solutions for the conditions of the mobility of the link group are proposed: (i) The first one is based on the differentiation of matrices which describe the coordinate transformation; (ii) The second one is based on the presentation of the link motion as a screw motion. It is proven that singularities in motion occur in the cases where: (i) Some or all links of the overconstrained group of links are aligned; (ii) The links of the group are not aligned but they form a mobile configuration, (iii) A Certain number of axes of revolute or cylindrical pairs belong to a ruled surface. Cases (i) and (ii) cover the situations when the oscillating driving link reaches its extreme positions. The determination of displacement functions is based on the modeling of the linkage by two open kinematic chains formed: (i) by links of the overconstrained group of links and (ii) the driving link and the frame. The structure of equations for the link displacements is related with the structure of the velocity Jacobian for the overconstrained group and simplifies the computation procedure. The proposed methods are illustrated with examples of RCRCR and 7R linkages.
Effect of Pivot Clearance on Head Positioning of a Rotary Actuator for Magnetic Disk Storage
Authors: Kakizaki T.
Published: January 2010

The effect of pivot clearance on the dynamic characteristics of a rotary actuator for head positioning in magnetic disk storage is numerically investigated. A motion equation which takes pivot clearance and pivot bearing elasticity into account is derived for a track-following servo-controlled actuator. Elastic deformation of a bearing as well as head positioning error increase in a sudden step when the bearing makes alternating impacts at the antipodes of the pivot shaft. Based on the result, design criteria are obtained for the maximum acceptable clearance for high accuracy in head positioning.
A Study of the Singular Configurations of Serial Manipulators
Authors: Wang Shih-Liang , Waldron Kenneth J.
Published: January 2010

A manipulator is at a singular configuration when the screws representing the instantaneous joint motions of the manipulator are linearly dependent, and the manipulator cannot be moved along an exact path with specified orientation in world coordinates. There are ∞3 singular configurations for a six-degree-of-freedom manipulator, and all these configurations constitute the singularity field. An algorithm is derived to trace the singularity field. Another algorithm presented in this paper finds all the joint screws reciprocal to a given wrench screw. Some new robotic applications are then possible using the principle of aligning a power tool with the screw of the reciprocal wrench.
A Higher-Order Analysis of Basic Linkages for Harmonic Motion Generation
Authors: Farhang K. , Midha A. , Bajaj A.
Published: January 2010

In an earlier work, a perturbation technique was first presented to obtain approximate simple harmonic equations for describing the output motions of rudimentary linkages, i.e., a crank-rocker and a slider-crank, with relativley small input cranks. The technique involved consideration of a small motion excursion about a so-called “mean linkage configuration.” These equations were facilitated through truncation of the binomial series expansion of the output motions, expressed in terms of the input crank angle. Assuming a small crank to ground link length ratio, terms containing second or higher powers of this ratio were neglected. This paper retains terms containing higher powers in an effort to improve upon (i) the definition of the mean linkage configuration, and (ii) the harmonic motion content representation of the output motions. The improvements made due to the “modified” equations, relative to the “original” ones, are pictorially presented as being significant.
Formulation of Dimensional Synthesis Procedures for Complex Planar Mechanisms
Authors: Olson D. G. , Erdman A. G. , Riley D. R.
Published: January 2010

This paper presents an overview of a component-based approach for the dimensional synthesis of planar mechanisms. The components on which the approach is based are called triads, dyads, and free vectors, and can be synthesized for up to five precision positions. A straight-forward method for formulating dimensional synthesis procedures for arbitrarily complex planar mechanisms is developed, and demonstrated by an example using inspection. The method utilizes the concept of the directed graph, which is an enhancement of the usual graph theory representation of mechanisms. Because the method is based on graph theory, it is believed that it could be easily automated.
An Efficient Method to Predict the Effect of Design Modifications
Authors: Rizai Matt N. , Bernard James E.
Published: January 2010

Static and dynamic analyses are important tools for the improvement of structural systems. Consider a system where a number of different changes may be synthesized to improve static and dynamic behavior. The analysis depends on numerical optimization schemes for systems with a large number of degrees of freedom. These analyses become computationally burdensome for redesign analysis. This paper presents an efficient method to predict the effect of design modifications on mechanical and structural systems with many degrees of freedom. The method minimizes a cost function which includes natural frequencies, size of design change and static deflections. It uses a finite-element preprocessor to find derivatives of mass and stiffness matrices and computationally efficient techniques to find eigen-value and eigenvector derivatives for use in the optimization.
Kinematics and Friction in Grasping by Robotic Hands
Authors: Ohwovoriole E. N.
Published: January 2010

Using the extended screw theory, grasping is analyzed in terms of the complete and partial constraint of a rigid body. The underlying kinematic theory is first reviewed and illustrated. The extended screw theory is then used to determine the disturbing and nondisturbing external wrenches, and resulting disturbances for a grasped object. This is a new application of the concept of total freedom based on the idea of component motions and the wrenches that can cause them. Determining the disturbing and nondisturbing wrenches is tantamount to determining the stability of the grasp in regard to total freedom. Finally, a novel method of incorporating friction in the kinematic analysis of grasping using screw theory is also developed using the concepts of apparent normals and apparent motions.
Dynamic Stability of Chain Drives
Authors: Ariaratnam S. T. , Asokanthan S. F.
Published: January 2010

The tension in power transmitting chains is subject to periodic fluctuation. This is brought about by factors such as polygonal action, eccentricity of sprockets, etc. A study of the dynamic stability of such a chain is presented. Instabilities due to polygonal action are investigated. The analysis is carried out by treating the chain as a travelling uniform heavy string.
Computer-Aided Fatigue Design of Power Transmission Shafts Using Three-Dimensional Finite Shaft Element and Updated Mean Stress Diagram
Authors: Bagci C.
Published: January 2010

A three-dimensional flexural shaft element is developed for elastic analyses of power transmission shafts and geared systems. It is used for the computer-aided fatigue design of three-dimensionally loaded power transmission shafts on many rigid or elastic bearings. Bagci’s mean stress diagram—which removes the flaw related to the load line slope of zero value in the presently used mean stress theories—is used to determine the failure value of the reduced fatigue strength of the shaft at the critical sections considered. Basic stresses are defined using maximum energy of distortion theory. An interactive computer program is prepared for fatigue design of power transmission shafts, in which some of the strength reducing factors for each notch location are determined using generalized expressions. The program initially locates the weakest section on the shaft, then it redefines the dimensions for the desired factor of safety, reliability and the fatigue life at that section. An application example is included.
Analysis of Dynamic Loads on Gear Teeth by Conjugato-Elasto-Dynamics (CED)
Authors: Chen Chih-Hsin
Published: January 2010

Though the dynamic loads on gear teeth have been investigated for more than half a century, there is, so far, still a need to develop a general analytical theory, which can take into account the effect of the tangential location change of the conjugate contact point due to profile error and elastic deformation on the dynamic loads. In this paper, such a theory, which applies not only the theory of dynamics and the theory of elasticity but also the theory of conjugate surfaces [1, 2, 3] to solve the problem, and which is hence called Conjugato-Elasto-Dynamics, or simply CED, is developed and briefly sketched. Equations for determination of the dynamic loads on gear teeth are derived, which can be solved numerically by an iterative method with the aid of computer and the finite element method (FEM).
A Method for Determining and Correcting Robot Position and Orientation Errors Due to Manufacturing
Authors: Broderick P. L. , Cipra R. J.
Published: January 2010

A method is presented for calibration of a robot to correct position and orientation errors due to manufacturing. The method is based on the shape matrix robot kinematic description. Each joint is individually and successively moved in order to explicitly calculate the shape matrix of each link. In addition, methods to correct for the errors in both the forward and inverse kinematic solutions are presented. The modification of the forward solution is a simple task. The modification of the inverse kinematic solution is a difficult problem and is achieved by an iterative technique which supplements the closed-form solution. An example of the calibration and inverse solution is presented to show the improvement in the accuracy of the robot.
An Experimental Study of Electro-Rheological Torque Transmission
Authors: Stevens N. G. , Sproston J. L. , Stanway R.
Published: January 2010

The electro-rheological (ER) effect is the name given to the phenomenon whereby the resistance to flow of certain special fluids can be controlled through the application of an electric field. To examine the utilization of ER fluids for torque transmission an experimental facility has been designed and constructed. This paper describes, in detail, the test facility and presents the results of a series of experiments to determine the torque transmission characteristics as a function of voltage and fluid temperatures. The results are analyzed to provide guidelines to assist in the development of practical ER devices.
Boundary Surfaces, Limit Surfaces, Crossable and Noncrossable Surfaces in Workspace of Mechanical Manipulators
Authors: Oblak D. , Kohli D.
Published: January 2010

The workspace of a regional structure of a manipulator is bounded by a Jacobian surface (where the Jacobian is singular) or a D-surface (where one or more of the joints achieve a limit position). The Jacobian surfaces and D-surfaces may also appear inside the workspace. In such a case, these surfaces are noncrossable for certain configurations and crossable for certain other configurations. In addition, there may be singular points which are crossable by all configurations of the manipulator. In this paper, a workspace analysis method has been developed for identification of these surfaces. Examples of RPP and 3R regional structures are presented for illustration.
Direct Computation of Grasping Force for Three-Finger Tip-Prehension Grasps
Authors: Ji Z. , Roth B.
Published: January 2010

This paper deals with the computation of grasping forces for grasps using three-fingered tip-prehension. Of primary interest is the optimization of the internal forces and the direct computation of the grasping force. Using geometrical reasoning, we derive the conditions for minimizing the dependence of the internal forces on contact friction. Based on these conditions, formulas are derived for calculating the optimal internal and grasping forces.
Design of Quick-Returning R-S-S-R Mechanisms
Authors: Suareo F. O. , Gupta K. C.
Published: January 2010

An algebraic method is presented to synthesize quick-returning R-S-S-R mechanisms which satisfy the given time-ratio and follower oscillation angle requirements. In these designs, the three parameters, which define the follower spheric joint, satisfy a quadratic condition. When the shaft angle between the input and output shafts is zero, this quadratic condition reduces to the equation of a circle which is a familiar classical result for the planar case. The solution space for the quick-returning R-S-S-R linkage is such that, for each set of choices for crank length a2, follower axial distance S4, and initial follower angle φ0, there are four sets of follower length a4, initial crank angle θ0, crank axial distance S2, and coupler length a3. These designs are screened so that they do not have branch defect, have transmission angle values in a given range, and have reasonable link length proportions.
Performance Analysis of a Variable Speed-Ratio Metal V-Belt Drive
Authors: Sun D. C.
Published: January 2010

A model of the metal V-belt drive (MBD), considering its detailed multiple-band and metal-block structure, and the ratio-change effect during its operation, is constructed and analyzed. A computational scheme is devised that adapts the analysis to the computation of the MBD’s performance for any specified drive-schedule. General performance characteristics of the MBD and an example illustrating its response to a given drive-schedule are presented. The use of the analysis and the computational scheme in the design of the MBD and in finding the optimum operating conditions is discussed.
The Complementary Roles of Knowledge-Based Systems and Numerical Optimization in Engineering Design Software
Authors: Ellsworth R. , Parkinson A. , Cain F.
Published: January 2010

In many engineering design problems, the designer converges upon a good design by iteratively evaluating a mathematical model of the design problem. The trial-and-error method used by the designer to converge upon a solution may be complex and difficult to capture in an expert system. It is suggested that in many cases, the design rule base could be made significantly smaller and more maintainable by using numerical optimization methods to identify the best design. The expert system is then used to define the optimization problem and interpret the solution, as well as to apply the true heuristics to the problem. An example of such an expert system is presented for the design of a valve anticavitation device. Because of the capabilities provided by the optimization software, the expert system has been able to outperform the expert in the test cases evaluated so far.
Some Factors Influencing Friction Brake Performance: Part 3—Computer Simulation of the Lining Wear Process in Friction Brakes
Authors: Barecki Z. , Scieszka S. F.
Published: January 2010

In this paper the simulative model of the friction lining wear process in a winding gear, post type, brake is presented. In the modelling procedure, the wear characteristics of the friction materials and the brake variables typical for winding brakes, for example, the elastic property of the brake elements were taken into consideration. The modelling of the friction lining wear process was used to predict associated changes in the pressure distribution, and other mechanical characteristics of the brake system.
Kinematic Analysis of Tendon-Driven Robotic Mechanisms Using Graph Theory
Authors: Tsai Lung-Wen , Lee Jyh-Jone
Published: January 2010

The kinematic structure of tendon-driven robotic mechanisms has been investigated with the aid of graph theory. The correspondence between the graph representation of the kinematic structure and the mechanism has been established. We have shown that the kinematic structure of tendon-driven kinematic chains is similar to that of epicyclic gear trains. We also have shown that, using the concept of fundamental circuits, the displacement equations of tendon-driven robotic mechanisms can be systematically derived from the kinematic structure. The theory has been demonstrated by the kinematic analysis of three articulated robotic devices.
Shape Optimization of Cam Profiles Using a B-Spline Representation
Authors: Sandgren E. , West R. L.
Published: January 2010

An arbitrary acceleration profile for the cam follower acceleration is generated using a B-spline representation. The control point locations for the B-spline become the design variables in the nonlinear programming problem. The B-spline representation provides for local control of the acceleration profile which is required in order to generate reliable optimization results. Constraints are imposed in order to place appropriate limits on the contact stress, lift, duration, acceleration, jerk, radius of curvature, manufacturing requirements, and to avoid cam-follower separation. The objective function may take on a number of forms depending upon the design requirements. The optimization is carried out with a gradient based penalty function algorithm. A specific example is presented in which the flow area is maximized for an internal combustion engine.
Optimum Selection of Discrete Tolerances
Authors: Lee W.-J. , Woo T. C.
Published: January 2010

Tolerancing involves considerations from all phases of the life cycle of a product including design, manufacturing, assembly, and inspection. Along with minimum cost and maximum functionality and interchangeability, the practice of tolerancing urges a designer to choose an appropriate manufacturing (or inspection) process as well. This situation is formalized as a discrete optimization problem. For an optimum selection of tolerances from a given discrete model involving various manufacturing processes, minimization of manufacturing cost is achieved under the constraint of tolerance stack-up. A random variable and its standard deviation are associated with a dimension and its tolerance. This probabilistic approach enables a trade-off between performance and tolerance (cost). But it also suggests probabilistic optimization. With the aid of a notion called the reliability index [8], tolerance selection is formulated as an integer programming problem. A branch and bound algorithm for ensuring optimum selection is developed by exploiting the special structure of the constraints. To make the enumeration tree small, monotonic relations among the reliability index, cost, and tolerance are examined. The algorithm is tested with examples.
Optimal Design of Traction Drive Continuously Variable Transmissions
Authors: Lim K. H. , Ullman D. G.
Published: January 2010

An optimal design technique for minimum power loss in traction drive continuously variable transmissions is developed. The general forms of the objective function and constraint equations are derived, and the formulated optimal design problems are implemented in a nonlinear programming algorithm. Kinematic analysis and optimal design problem formulation are performed for a selected traction drive configuration as an example of the procedures.
‘Perfect’ Spring Equilibrators for Rotatable Bodies
Authors: Streit D. A. , Gilmore B. J.
Published: January 2010

A new equilibrator design approach based on system potential energy functions is presented. This approach was used to discover a group of spring equilibrators which perfectly balance a rotatable rigid link at every orientation angle through 360 deg of link rotation. Springs are connected between a rotatable link and ground, where one end of each spring is connected to the rigid link and the other end of each spring is connected to ground. The rigid link is connected to ground by a pin joint and is free to rotate about that joint. The conditions for existence and the design equations for all equilibrators which fall into this category are developed and presented. Three designs appear to offer unique advantages over the infinite number of design options available.
An Efficient Algorithm for Global Optimization in Redundant Manipulations
Authors: Wang Z. , Kazerounian K.
Published: January 2010

A method is developed to resolve the redundancy of serial robotic manipulators. The main characteristics of this method are as follows: (a) The solution is conservative (unique); (b) It globally (over the task period) optimizes the objective function; (c) It is computationally very fast. In fact, it is about three orders of magnitude faster than solving for the exact boundary value problem.
Further Applications of Group Theory to the Enumeration and Structural Analysis of Basic Kinematic Chains
Authors: Tuttle E. R. , Peterson S. W. , Titus J. E.
Published: January 2010

The use of finite symmetry groups to enumerate basic kinematic chains has been extended by making use of the subgroup structure of the symmetry groups. This refinement not only makes the enumeration of kinematic chains considerably more efficient, but also permits the enumeration of all distinct inversions of each of the chains found. As examples, all chains with 2, 3, 4, and 5 independent loops and 1, 2, or 3 degrees of freedom and their inversions have been found on a personal computer.
A Statistical Analysis as a Criterion of Soil-Machine System
Authors: Manatakis E. , Drakatos P.
Published: January 2010

The present work is concerned with the determination of a stochastic model, which describes the interaction of different parameters involved in the soil-machine system, as a function with of the earth moving equipment efficiency. The stochastic model is valid for every case and it consists of an ellipsoid describing the particular soil-machine system.
Simple Stress Formulae for a Thin-Rimmed Spur Gear. Part 3: Examination of the Calculation Method and Stress State of Internal Spur Gear
Authors: Chong Tae Hyong , Kubo A.
Published: January 2010

Tooth fillet and root stresses of an internal spur gear which is fixed by bolts or supported by pinned coupling were measured. The stress values are compared with those obtained by the simple calculation method developed in the previous reports [1, 2] and with those by the FEM calculation. Those values have shown fairly good agreement, and the validity of this calculation method is shown. The difference of the stress state for the cases of bolt fixing internal gear and of roller supporting internal gear is discussed.
Helical Gears With Circular Arc Teeth: Simulation of Conditions of Meshing and Bearing Contact
Authors: Litvin F. L. , Tsay Chung-Biau
Published: January 2010

Methods proposed in this paper cover: (a) generation of conjugate gear tooth surfaces with localized bearing contact; (b) derivation of equations of gear tooth surfaces; (c) simulation of conditions of meshing and bearing contact; (d) investigation of the sensitivity of gears to the errors of manufacturing and assembly (to the change of center distance and misalignment); and (e) improvement of bearing contact with the corrections of tool settings. Using this technological method we may compensate for the dislocation of the bearing contact induced by errors of manufacturing and assembly. The application of the proposed methods is illustrated by numerical examples. The derivation of the equations is given in the Appendix.
Factors That Affect the Fatigue Strength of Power Transmission Shafting and Their Impact on Design
Authors: Loewenthal S. H.
Published: January 2010

A long-standing objective in the design of power transmission shafting is to eliminate excess shaft material without compromising operational reliability. A shaft design method is presented which accounts for variable amplitude loading histories and their influence on limited life designs. The effects of combined bending and torsional loading are considered, along with a number of application factors known to influence the fatigue strength of shafting materials. Among the factors examined are surface condition, size, stress concentration, residual stress, and corrosion fatigue.
Adaptable Fixture Design: An Analytical and Experimental Study of Fluidized-Bed Fixturing
Authors: Gandhi M. V. , Thompson B. S. , Maas D. J.
Published: January 2010

Computer-integrated flexible manufacturing systems are designed to respond quickly and economically to varying production requirements. Since an essential ingredient of all manufacturing operations is fixturing, if these modern manufacturing systems are to be truly flexible, then the fixturing must be adaptable also. Traditional design philosophies focused on dedicated fixtures are clearly inadequate for these applications. This paper reports on an innovative class of adaptable fixtures based on particulate fluidized beds. This mode of fixturing exploits the ability of these devices to change from a solid phase to a liquid phase and vice versa. Design criteria for the holding ability of this novel class of fixtures is established herein, and the proposed design philosophy is validated by an experimental program.
A Variational-Vector Calculus Approach to Machine Dynamics
Authors: Haug E. J. , McCullough M. K.
Published: January 2010

A variational-vector calculus approach is presented to define virtual displacements and rotations and position, velocity, and acceleration of individual components of a multibody mechanical system. A two-body subsystem with both Cartesian and relative coordinates is used to illustrate a systematic method of exploiting the linear structure of both vector and differential calculus, in conjunction with a variational formulation of the equations of motion of rigid bodies, to derive the matrix structure of governing multibody system equations of motion. A pattern for construction of the system mass matrix and generalized force terms is developed and applied to derivation of the equations of motion of a vehicle system. The development demonstrates an approach to multibody machine dynamics that closely parallels methods used in finite-element structural analysis.
Optimum Nonlinear Suspension Systems
Authors: Metwalli S. M.
Published: January 2010

Global optimal isolation is presented in this paper. Results indicate that to optimally isolate a system, it should be totally disconnected from the disturbance. A model is then selected to optimize nonlinear suspension systems which, in the limits, approach optimal isolation characteristics. Nondimensional design parameters that themselves are made to be dependent on the input are employed. A step disturbance is selected to equivalently represent real excitations. The objective function incorporates the tire-terrain normal force as an indicator of the vehicle controllability which is unconstrained or constrained by a comfort criterion (acceleration). The advantages of optimized realistically nonlinear systems over their linear counterparts are indicated.
Kinematic Structural and Functional Analysis of Wobble-Plate Engines
Authors: Yu Z. , Lee Ting W.
Published: January 2010

This paper concerns the development of a procedure for systematic searching for mechanisms, classifying them, and screening for the optimum mechanism structure for wobble-plate engines. It includes two parts. The first part is on kinematic structural analysis, including the development of a procedure for the structure classification of 150 mechanisms obtained as a result of an exhaustive search from the prior arts, as disclosed in nearly 1000 patents between 1874 and 1982, and other publications. The second part is on functional analysis, which screens for an optimum design based on a set of judgment criteria. Such optimization criteria are developed in this paper and applied to a group of representative mechanisms derived from the structure analysis. Recommendations such as design guidelines are presented. The general nature of the approach—following the method of separation of kinematic structure and function [1] and combining mathematical approach and design heuristics—is demonstrated here in the case of wobble-plate engine mechanisms and is believed to be useful in type synthesis and design of mechanisms of realistic complexity.
A Comparison of Test Results for Flat-Plate Water-Heating Solar Collectors Using the BSE and ASHRAE Procedures
Authors: Jenkins J. P. , Hill J. E.
Published: January 2010

Five solar collectors were tested according to the BSE and ASHRAE test procedures and the results compared. All five collectors tested were modular, flat-plate, water-heating, and included single- and double-glazed designs with and without selectively coated absorbers. In both procedures, collector efficiency curves are determined. The ASHRAE procedure consists exclusively of outdoor testing whereas the BSE procedure requires a combination of outdoor and indoor testing (no irradiation) to determine the collector’s optical and thermal loss characteristics, respectively. During the indoor testing in this study, the environmental test conditions were controlled and regulated by use of specially built environmental simulators to investigate the effect of wind speed and “sky” temperature on the thermal loss characteristics of the collectors. The simulators provided stable uniform wind speeds in the range of 0 to 7.1 m/s across the collectors and sky temperatures above the collector ranging from ta (ambient-air temperature) to ta - 19 K.
Design and Construction of an Ocean Thermal Energy Conversion Test Plant
Authors: Trimble L. C. , Potash R. L.
Published: January 2010

Mini-OTEC, shown in Fig. 1, is the first at-sea, closed-loop Ocean Thermal Energy Conversion (OTEC) system using surface and deep seawater to generate electric power. The Mini-OTEC cycle is installed on a moored barge incorporating the cold water pipe (CWP) in the single anchor leg. The design seawater temperature difference (ΔT) of 36°F provides thermal resource for a gross power output of 50 kW. This paper presents an overview of the Mini-OTEC project, including a description of the power plant, control system, instrumentation, and CWP mooring system.
The Impact of Screen Printing on the Cost of Solar Cell Metallization
Authors: Taylor W. E. , Mardesich N. , Gay C. F.
Published: January 2010

Photovoltaic generation of electric power requires substantial reduction of costs to tap significant markets. A major cost element in the technology of solar cell fabrication for space application is formation of electrical contacts by evaporation of metals through shadow masks. Application of conductive ink pastes by screen printing provides several mechanisms for cost reduction. Screen printing techniques have been developed for fabrication of miniature electronic circuits on ceramic substrates. The process is readily automatable, and equipment with high throughput rates is available. Thus, screen printing results in reduced investment, tooling and labor costs. Silver is required for the front metallization grid, and additional savings result from application of metal only where needed. Substitution of aluminum for silver at the back contact provides further material cost savings. Metallization costs by this method are projected to be less than .05 dollar (1975) per watt as compared to about 16.00 dollars per watt by evaporation techniques.