This paper uses linear quadratic optimal control theory to design high-speed Dwell-Rise-Dwell (D-R-D) cams. Three approaches to D-R-D cam design are compared. In the first approach the cam is designed to be optimal at a fixed operating speed, i.e., a tuned cam design is obtained. In the second approach the cam profile is determined by minimizing a sum of quadratic cost functions over a range of discrete speeds, thus producing a cam-follower system which is optimal over a range of speeds. The third technique uses trajectory sensitivity minimization to design a cam which is insensitive to speed variations. All design methods are formulated as linear quadratic optimal control problems and solved using an efficient numerical procedure. It is shown that the design techniques developed can lead to cams that have significantly lower peak contact stress, contact force and energy loss when compared to a polydyne cam design. Furthermore, the trajectory sensitivity minimization approach is shown to yield cams that have lower residual vibration, over a range of speeds, when compared to a polydyne cam design.

Abstract The classical cardanic motion and the swinging-block linkage are basic planar mechanisms. In the following investigation, the objective is the analysis of their three-dimensional (and, hence, more versatile) counterparts: the skew slider-crank mechanism and the skew swinging-block linkage. These linkages as far as we are aware, have not yet been analyzed analytically. An analysis utilizing their algebraic geometry will be instructive in determining their displacements and derivatives in closed form. This, in turn, should be useful in facilitating three-dimensional applications. With the ever-increasing sophistication in the area of mechanisms design and analysis, we believe that the time has come for the analysis of these linkages, including their algebraic geometry. This is the objective of this investigation.

A quasi-static model has been developed for a silent (inverted-tooth) chain drive incorporating a rocker-pin-jointed chain and involute-toothed sprockets. The kinematic effects of rocker-pin clearances and link/sprocket engagement are modeled and the influence of various model parameters on the chain drive torque-ratio variation, due to chordal action, is examined. In some cases, this variation is found to be less than that for equivalent pin-jointed chain drives. Additionally, the center distances corresponding to the maximum and minimum torque variation are not fixed, as in the case of a pin-joined chain. An optimization method is used in determining the governing geometric constrains as multiple joint configurations can occur, given the rocker-pin joint clearances. The resulting system of equations is fully constrained for a physically consistent chain configuration.

It is well known that the circulating power in gear trains can be many times greater than the input power. Such circumstances require that in the design of split-power gear drives, a preliminary power-flow analysis be carried out. In this investigation a systematic method for the power-flow and static-force analysis of spur-gear drives is presented. The manner in which the procedure is applied has some similarities with an algorithm for kinematic analysis previously suggested by one of the authors. Following a brief review of previous work, the theoretical bases of the new methodology of analysis are discussed and numerical examples developed.

The analysis of mechanical efficiency constitutes an important phase in the design analysis of gear drives. The objective of this investigation has been the development of a general algorithm for the determination of efficiency in split-power spur-gear trains. The model includes meshing losses only; for a more realistic estimation other sources can be considered separately.The systematic nature of the formulation, based on the dual correspondence between the kinematic structure of the gear drive and a labelled graph, allows a ready coding of the efficiency analysis in a general computer program. The numerical results are in line with those given by other authors using different methodologies.

The theory has been developed for the design of a new mechanical component: variable-ratio chain drives with noncircular sprockets and minimum slack. The theory is based on a kinematic correspondence between noncircular chain drives and non-circular gears. This in turn permits the development of an algorithm for minimizing chain slack. The theory is applicable to a wide range of mechanical equipment, including bicycles and nonuniform motion transmissions involving band drives, tape drives, and timing belts. Such drives may or may not require a tensioner, but if they do, tensioner displacement will be minimal. Numerical examples illustrate applications to the design of an optimum bicycle configuration and a harmonic-motion generator.

ABSTRACT This paper investigates the effects of load offset on the equilibrium and stability of two-dimensional lifting rigs. To accomplish this task the potential energy function, the equations of equilibrium, and the conditions for stability are derived. In general, the nonlinear set of equilibrium equations cannot be solved by standard numerical techniques such as Newton's method. Thus, a robust continuation algorithm is implemented for the solution of these equations. Results presented include stability boundary plots that can be used in the design of lifting rigs. Also illustrated is the effect of load offset on the rig platform angle.

A new method for the representation of the kinematic structure of mechanisms has been proposed. This scheme is an order-of-magnitude faster in enumerating mechanisms than the conventional characteristic-polynomial approach. Moreover, unlike the traditional approach, it never fails to identify a mechanism and all structural information relating to the mechanism can be retrieved from this representation. Classification of mechanisms based on structural characteristics is built-in as well. Using this method, the graphs of approximately one million kinematic chains have been generated and stored in a computer.

A kinematic analysis has been developed for the motion of roller chain drives, which is exact for relatively slow-speed chain drives with negligible wear. The results shed new light on chordal or polygonal action, and the associated impact velocity and motion fluctuation of the chain drive. The results have also revealed the existence of a remarkable degree of sensitivity of chain performance with respect to center distance including discontinuities in the motion derivatives. This in turn provides a new opportunity for the optimization of chain drives by optimizing center distance both in the design stage, as well as during installation and maintenance.

In recent times, the emphasis on increased vehicle fuel economy has spurred considerable interest in the development of variable-valve-timing (VVT) mechanisms for internal-combustion engines. This investigation focuses on the determination of the kinematic structure and the creative design of VVT mechanisms. Following a review of some representative existing VVT mechanisms, several potentially useful, proposed VVT configurations are described; one of these is proportioned and analyzed in some detail

Graphene has shown great potential for use in biosensors because of its versatile surface modification, good water dispersibility, and extraordinary electrical conductivity. Here, a novel enzyme-free and all-graphene electrochemical immunosensor, based on two novel graphene nanocomposites, for the ultrasensitive immunosensing of α-fetoprotein (AFP) was reported. Noncovalent ultrathin gold nanowire functionalized graphene sheets (GNWs/GO) with the extraordinary biological and electrical properties, which exhibited high water solubility and further biological molecule functionalization, was prepared in situ solution phase to be used as an enhanced electrochemical sensing platform. In addition, a new electrocatalyst, CuS nanoparticle-decorated graphene (CuS/GO) composites was successfully prepared by a simple method for in situ growth of CuS on the surface of graphene sheets. Covalent binding of the detection antibody of AFP on the CuS/GO composites produced a sensitive electrochemical bioprobe for detection of AFP by sandwich immunosensing. The corresponding immunosensor, employing an inexpensive and portable 3D paper-based analytical device, possessed a wide calibration range of 0.001–10 ng mL−1 and a low detection limit of 0.5 pg mL−1 (S/N=3), which was successfully applied to the detection of AFP in serum samples from both healthy people and cancer patients. The present work thus demonstrated the promising application of graphene-based nanocomposites in developing highly sensitive, environmentally friendly, and cost-effective electrochemical biosensors.

The workspace of a three-axis, turning-pair connected robot arm has been optimized using algebraic criteria for extreme axial and radial reach and the elimination of voids (Freuden stein and Primrose 1984). Based on these criteria, an effi cient, systematic search procedure has been developed for maximizing the workspace and the rvorkspace-to-void ratio of the R3 robot arm.

The Generalized Oldham Coupling 1 K. Mitome. 2 The authors are to be congratulated for inventing this new mechanism, establishing design guidelines, and developing a practical application by using its inherent imbalance to advantage.The discusser has a special interest in this mechanism too, because he has also presented the same mechanism before [13], though his paper deals with only deduction of the existence of this mechanism, detailed analysis of angular motion between two shafts connected by this coupling, and experimental verification.In this discussion, the discusser would like to offer the following comments.First the amount of sliding S n and S a have been obtained on Tsai's research on the design of drag linkage with optimum transmission angle, but in this case these S n and S n can also be obtained directly from the corresponding fixed block double-slider crank mechanism shown in Fig. 12.Besides Fig. 12 helps us to grasp the meanings of v max , c min , /x max , /Lt min , and r] at a glance.Secondly, the motion of floating disk can be more clearly understood by using both of the fixed and the moving centrode of this disk.That is, letting the fixed centrode be denoted by Cf and the moving centrode by C m as in Fig. 13, the moving centrode C m attached on the floating disk rolls on the fixed centrode C f attached on the fixed coordinate system A-xy without any slip.The motion of the floating disk is similar to that of the "hula-hoop."As a special case, in the case of the Oldham coupling, C f becomes a circle having radius a/2, and C," does a circle having radius a.Finally the discusser thinks that the pressure angle is to be taken into consideration in the future, especially when rollers are used instead of projections.It is a great honor to be given a chance to discuss the new mechanism.

A new mechanism, which we have called the generalized Oldham coupling, has been described. With a circular-arc construction for its projections and grooves, the coupling has been shown to be analyzable in terms of an equivalent drag linkage, which is generally much larger than the coupling. The kinematic analysis of the coupling, including sliding motions, has been given and general considerations regarding transmission-angle optimization and dynamic equivalence have been pointed out. The application of the coupling to phase changing is reviewed and a general form of construction involving rollers has been described and shown to yield a phase-changing capability of a very general nature.

A general procedure has been developed for the kinematic analysis of complex bevel-gear trains in which the motion of the arm can be of mobility two or greater (i.e. the arm can rotate about two or more nonparallel, intersecting axes). The analysis of a three-degree-of-freedom gear train used in guiding the motion of the end effector of a recently developed industrial robot is described in detail.

The literature on the internal forces in Cardan joints, which is sparse, tacitly assumes the vanishing of certain force components. For a joint of ideal proportions the torque transmission has been analyzed, but the force transmission has been only partially developed. In this investigation the displacement analysis and static force and torque analysis of a Cardan joint with manufacturing tolerances has been derived. The forces have been shown to be statically indeterminate by a degree of three. An experiment was undertaken to check on the validity of the assumed vanishing of the abovementioned force components. For the particular joint tests this assumption was not valid. Based on the displacement analysis, which includes the axial sliding at the joints in the presence of manufacturing errors, optimum tolerances can be determined in the design stage. Further experimentation is recommended in order to determine representative magnitudes of the abovementioned axial joint forces in joints of varying constructions and sizes. Together with the static analysis which has been developed in this investigation this will permit the sizing of universal joints in the design stage.