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EDITORIAL

J. Mech., Trans., and Automation. 1983;105(1):1. doi:10.1115/1.3267338.
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Abstract
Commentary by Dr. Valentin Fuster

BOOK REVIEWS

J. Mech., Trans., and Automation. 1983;105(1):2-3. doi:10.1115/1.3267341.
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Abstract
Commentary by Dr. Valentin Fuster

REPORTS

J. Mech., Trans., and Automation. 1983;105(1):4-9. doi:10.1115/1.3267344.
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Abstract
Commentary by Dr. Valentin Fuster

COMMENTARY

J. Mech., Trans., and Automation. 1983;105(1):11-12. doi:10.1115/1.3267329.
Abstract
Topics: Robots , Mechanisms
Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):12-13. doi:10.1115/1.3267332.
Abstract
Topics: Robots , Design
Commentary by Dr. Valentin Fuster

RESEARCH PAPERS: Robotic Manipulator and Mechanisms Papers

J. Mech., Trans., and Automation. 1983;105(1):15-22. doi:10.1115/1.3267337.

Some kinematic structures suitable for use in robot manipulator designs are constructed in terms of components. General properties of kinematic structures are considered and a method for combining two structures given. Two types of component, namely actuation and distribution components, are specified. Modification of the kinematic structures is effected by transfer of drives. Existing designs for robot manipulators are examined in terms of their kinematic structures and some new designs are generated.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):23-27. doi:10.1115/1.3267339.

Many kinds of robot arms with five degrees of freedom are widely used in industry for arc welding, spray painting, assembling etc. It is necessary to be able to compute joint displacements when such devices are computer controlled. A solution to this problem is presented and the analysis is illustrated by a numerical example using the most common industrial robot with five axes. Further, special cases are discussed using screw theory.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):28-34. doi:10.1115/1.3267340.

In this paper we present an analytical technique, based on Newtonian mechanics with screw calculus and dual-number matrices, to derive the dynamic equations of a multi-rigid-body open-chain system. Next, we outline a systematic procedure to derive closed-form expressions for the joint forces and torques and the reaction forces and moments exerted on each member in the system. Finally, we illustrate the procedure with two examples of robot manipulators. It is hoped that the analytical technique presented here will provide a meaningful alternative, or serve as a complement to existing methods, in our common effort to advance the design of robot manipulators.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):35-41. doi:10.1115/1.3267342.

This paper deals with several of the basic concepts in the kinematics of mechanical hands. Several different types of finger contacts are modeled and used in a number synthesis of three-fingered hands. Screw theory is used to show which finger configurations allow complete immobilization of the gripped object relative to the fingers, and also allow for the manipulation of the object by the fingers while maintaining the grasp. Shown in this paper is how to determine the forces applied by the fingers on the object, and also how to compute the velocities of the fingers and the object. The analysis developed in this paper is shown to lead to a hand with three fingers, each with three turning joints, and having friction contacts with an object at three separate points.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):42-51. doi:10.1115/1.3267343.

This paper presents a method for analyzing the complete behavior of industrial robotic manipulators with complex-shape flexible links, including the effects of the manipulator’s control systems and actuators. The kinematics and dynamics of the manipulator are expressed in terms of 4 × 4 matrices. The distributed flexibility and mass properties of the links are obtained by using readily available finite-element models and programs. The resulting equations are transformed to produce a method which is computationally efficient through a procedure called Component Mode Synthesis. The method is applied to an actual industrial manipulator and the results are compared to experimental data, showing good correlation. Link flexibility is demonstrated to have significant impact on system performance and stability.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):52-57. doi:10.1115/1.3267347.

An algorithm is developed to determine the workspace on an arbitrary plane for an n -R robot. The algorithm is based on a linear optimization technique and on small incremental displacements applied to coordinate transformation equations relating the kinematic parameters of the n -R robot. The algorithm provides flexibility to let the user treat the robot hand as a point, a line, or a rigid-body. The revolute pairs of the robot may execute full or partial rotation. The proposed method may be extended to incorporate in a robot the existence of prismatic pairs along with revolute pairs.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):58-61. doi:10.1115/1.3267348.

The subject of this paper is the degree of the algebraic line complexes traced by mechanisms consisting of three connectivity-1 couplings arranged in series. A theorem which gives the degree is presented and proved. The theorem is applied to the eight mechanisms consisting only of single kinematic pairs (revolute and prismatic). In the discussions of some of these mechanisms the degree is determined independently of the proof of the theorem. The theorem is also applied to the mechanisms of some commercial robotic manipulators.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):62-69. doi:10.1115/1.3267349.

This paper presents an analytical investigation of manipulator workspace. The first part presents the derivation of a set of recursive equations in terms of motion and design parameters representing the workspace. These formulas are basic for the determination of the characteristics as well as the shape of workspace. The remainder of the paper concerns the investigation of the existence of hole and void in workspace. A set of criteria is formulated. Algorithms for implementing these criteria are developed. Manipulators with both unlimited and limited revolute joints are studied in this investigation.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):70-77. doi:10.1115/1.3267350.

This paper presents a theorem regarding manipulator workspace and, based on this theorem, a manipulator performance index is introduced. It is found that for a given manipulator structure the ratio of the volume of the workspace to the cube of its total link length is a constant. Algorithms for outlining the boundary profile of workspace and for quantitative evaluation of its volume are presented. A computer package, KAM, is developed, which implements the theories and algorithms developed in this investigation as well as in a companion paper [1]. Several specific examples are given to illustrate the application of the performance index and the capability of KAM.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):78-87. doi:10.1115/1.3267351.

Based on the displacement equations for the general n-bar, single-loop spatial linkage, obtained elsewhere, the displacement analysis for a special case of the 7R spatial mechanism is carried out. In this mechanism the successive rotation axes are perpendicular to each other, the distances between axes 3-4, 4-5, 5-6, are equal and the offsets along axes 4 and 5 are zero, when input axis is labeled axis 1. In this fashion, there still remain nine free linkage parameters. Input-output equation is of the eighth-degree in the tangent of half the output angle. A particular case of this one, where all the distances between axes are equal and all the offsets along axes are zero, leads to an input-output equation of the fourth-degree in the same quantity, with a maximum of four closures. This mechanism resulted to be a double-rocker.

Commentary by Dr. Valentin Fuster

RESEARCH PAPERS: Design Automation Papers

J. Mech., Trans., and Automation. 1983;105(1):88-96. doi:10.1115/1.3267353.

This paper proposes a design optimization method in which simplified structural models and standard mathematical programming methods are employed in order to optimize the dynamic characteristics of machine-tool structures in practical applications. This method is composed of three phases: (1) simplification, (2) optimization, and (3) realization. As design variables employed in this optimization are greatly reduced, machine-tool structures are optimized effectively in practice. With large design changes being conducted through this multiphase procedure, dynamic characteristics of machine tools can be greatly improved. This method is demonstrated on a structural model of a vertical lathe.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):97-103. doi:10.1115/1.3267354.

In 1970, Pshenichny published a linearization method for nonlinear programming in Russian, which has been overlooked in the English literature. The method is essentially a recursive quadratic programming technique with an active set strategy. Pshenichny has proved global convergence of the method and convergence rate estimates. The method is presented in this paper, with convergence theorems stated. Application of the method is made to shape optimal design, kinematic optimization, and dynamic system optimization. The method is shown to be particularly attractive in utilization of mechanical design sensitivity analysis techniques and performs well on all classes of problems treated.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):104-107. doi:10.1115/1.3267326.

Error Linearization (EL), an iterative curve-fitting procedure recently proposed for designing minimum squared error four-bar function generating mechanisms, suffers from frequent instability. The cause seems to be the near singularity of a certain 3×3 matrix, which produces artificially large steps, usually toward designs with unrealistically short driver and follower. This degenerate case proves unfortunately to be the true global minimum. To bring this behavior under control, the coupler length, formerly regarded as an independent design variable, is made to depend on the driver and follower lengths. They are determined by solving a now well-conditioned 2×2 set of error linearization equations. In an example this Stabilized EL procedure (SEL) located five reasonable locally minimal designs which would have been missed by the unstabilized version.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):108-112. doi:10.1115/1.3267327.

In the high-speed page printing systems used as peripherals to computers, the paper moves at a speed of around 30 in./s. The printing and punching of the paper has to be done when the paper is in motion. If the punching is not finished in a short enough time, the paper would get torn up by the punchette. In a typical punch assembly as used in modern page printing systems, a plunger is driven forward by the force of a solenoid. Plunger impacts the punchette which in turn punches a hole in the paper which is in motion. To minimize the flight time of the punchette with the object of increasing paper speed, the design parameters of the punch assembly must be carefully selected. In this paper, a model for the punch assembly is developed. The necessary equations for plunger and punchette motion are derived. The design parameters, such as the masses of the plunger and punchette, constants for springs used in the assembly, force generated by the solenoid, and the gap between the plunger and punchette, are varied using a Rosenbrock algorithm to minimize the flight time of the punchette. The results obtained indicate that by the use of a Computer-Aided Design approach optimal values of design parameters can be found before the development of prototypes and experiments.

Commentary by Dr. Valentin Fuster

RESEARCH PAPERS: Power Transmission and Gearing Papers

J. Mech., Trans., and Automation. 1983;105(1):113-121. doi:10.1115/1.3267328.

Sealing systems consisting of stationary seat and rotating seal surfaces are considered. The seal and seat surfaces may be in surface contact or in line contact. The geometry of different types of seal-seat surfaces is discussed: (a) with surface contact between conical and spherical surfaces and surfaces of revolution, (b) with line contact of a surface of revolution and a conical surface. A new method for synthesis of conjugated surfaces for sealing systems is proposed. The method is based on specific applications of the general theory of enveloped surfaces. Seal and seat surfaces synthesized by this method are in surface or line contact at the closed position and do not interfere with each other at any open position. Relations between design parameters of sealing systems to meet these requirements are developed. The method presented uses general assumptions and can be applied for various types of seal-seat surfaces. Examples of synthesis of seal-seat surfaces are provided.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):122-128. doi:10.1115/1.3267330.

A general method is presented for the determination of the minimum number of teeth that can be cut in a spur gear without undercutting by a rounded-tooth tip hob. The minimum number of teeth to produce undercutting was investigated for three trochoid/tooth-profile relations: (1) trochoid tangent to the involute profile at the base circle, (2) trochoid tangent to a straight portion of the tooth flank, and (3) trochoid intersecting the involute profile at the base circle. It was found that in order to avoid undercutting, the minimum number of teeth cut into a gear occurs when the trochoid is tangent to the involute at the base circle. There is no set of hob parameters such that the trochoid intersects the involute profile at the base circle nor does the case of the trochoid being tangent to a straight flank exist. A set of figures representing the variation of the amount of undercutting versus the number of teeth, radius of hob-tooth tip, hob addendum, cutting pressure angle, and the corresponding derivatives are included for a typical gear.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):129-131. doi:10.1115/1.3267331.

Employed is a new version of boundary-integral equation methods of the elasticity theory. It gives precise, reliable and simple numerical solution of the plane problem of gear tooth strength rating. The solution and program are proposed for every-day design calculation.

Commentary by Dr. Valentin Fuster
J. Mech., Trans., and Automation. 1983;105(1):132-137. doi:10.1115/1.3267333.

An analysis of tooth profile changes in the transverse plane of circular-cut, spiral-bevel crown gears is presented. The analysis assumes a straight-line profile in the midtransverse plane. The profile variation along the centerline is determined by using expressions for the variation of the spiral angle along the tooth centerline, together with the profile description at the midtransverse plane. It is shown that the tooth surface is a hyperboloid and that significant variations in the pressure angle are possible.

Topics: Gears , Pressure
Commentary by Dr. Valentin Fuster

RESEARCH PAPERS: Medical Devices and Sporting Equipment Paper

J. Mech., Trans., and Automation. 1983;105(1):138-145. doi:10.1115/1.3267336.

A five degree-of-freedom model of a bicycle and rider was developed to investigate the system response to inputs from the road as the first step in a unique fatigue failure analysis of a bicycle frame. Transfer functions relating the induced frame loads and the road input spectra are given, as are the frame load spectra for realistic levels of road inputs. The transfer functions show that the system is lightly damped and responds more strongly to inputs at the rear wheel than to inputs at the front. The load spectra show that the load picture is one of small fluctuations around a relatively large static offset.

Commentary by Dr. Valentin Fuster

DISCUSSIONS

Commentary by Dr. Valentin Fuster

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