Rao V. Dukkipati

Independently Rotating Wheel Systems for Railway Vehicles-A State of the Art Review

SUMMARY This paper surveys the state-of-the-art in the field of Independently Rotating Wheel systems (IRW) for railway vehicles. Various methods that have been adopted to provide guidance capability to the system are discussed. Results of the stability and response characteristics of such systems obtained through both experimental and analytical efforts by various researchers are reviewed. Some critical research needs are identified.

Dynamics of a Wheelset on Roller Rig

SUMMARY The expressions for the longitudinal creepage, lateral creepage and spin quantities are derived for a railway wheelset on a roller rig. The analysis takes into account the initial canting and the yaw motion of the rollers. A reduced set of Equations of motion representing the four degrees of freedom is also derived.

Kinematic analysis of robot's manipulators using consecutive analysis of train components

Abstract A useful method for kinematic analysis of robots manipulators is presented. For the purpose of kinematic analysis, the manipulator is treated as a number of master train components. For each master train component, geometric constitutive equations for use in kinematic analysis are developed. The kinematic analysis of robots manipulators are performed as parts of the master components using a mathematical programming procedure and the principle of superposition. The analysis is followed in sequence from one train component to another as they form the entire robots manipulator. Numerical examples are presented to illustrate the proposed technique. Results are compared with the Denavit and Hartenberg approach.

Design synthesis of a gyrogrinder using direct search optimization

Abstract A novel grinding mechanism operating on the principle of gyroscopic tracking of arbitrary contours is presented. The mathematical model describing the mechanism of gyrogrinding and the conditions under which the grinding wheel remains in contact with the periphery of template are established. The design parameters that greatly influence the performance of gyrogrinding are identified as the radius of the grinding wheel, the length of the spin axis, rotational speed of grinding wheel, and the mass polar moment of inertia of rotor and inner gimbal. In this paper, the design synthesis of a gyrogrinder is formulated as an optimization problem so that the optimal values of the design variables are calculated using a direct search multiparameter optimization method for continuous grinding with no dynamic shattering of grinding wheel. Three typical templates: elliptical, Limacon of Pascal and Four Leaved Rose, which represent possible shapes in cam production were considered and the optimal values of design parameters for each cam configurations were found using the optimization strategy. Results show that optimal design parameters lie within a small range for the three cam configurations. The mean optimal values of the design parameters were calculated and used in the dimensioning of the rotor and inner gimbal. A prototype was then built based on this investigation and when tested functioned effectively grinding the template. This paper illustrates the use of computer-aided optimization in the design synthesis of a gyrogrinder.

A new iterative algorithm for kinematic synthesis of gear drives for optimal speed ratio

Abstract The double composite gear trains offer attractive design features. However, their analysis using the algebraic equations method involves lengthy and tedious manual manipulations. The existing theories of composite gear trains is useful in this process to some extent, but it will not facilitate development of an algorithm suitable for all kinematic versions of a drive. The present algorithm based on the Unified Theory has been used for analysis of all the 18 versions of the drive with similar structure. The input data is simplified to that of feeding values of index exponents for the applicable versions. The optimal version of the twelve speed drive is synthesized with the present algorithm from the 18 versions belonging to open type having similar structure.

An efficient iterative computational algorithm for design synthesis of 4 × 3 type double composite gear trains

Abstract The arrangement of gears of double composite gear trains to form numbers of combinations gives rise to various kinematic inversions having the same number of output speeds. Application of algebraic technique of analysis to drives providing output speeds greater than six involves manual manipulations of considerable magnitude. The General Theory could provide open form solutions but could not lead to a generalized compute algorithm for design synthesis. An efficient iterative computational algorithm has been developed in this work based on the Unified Theory to analyze eighteen applicable kinematic inversions.

A rapidly convergent algorithm for computerized synthesis of machine tool gear drives

Abstract A complete analysis of all the kinematic versions of a drive having output speeds larger than six and employing the algebraic equations method involves a great deal of manual manipulations. The general theory of composite gear trains could reduce the tedium to some extent, but it could not lead to a general computer algorithm for design synthesis. The present algorithm based on the unified theory provides a computerized method to find the rank of any version in the kinematic merit order. The input data is simplified to that of feeding index exponent values for the applicable versions. The algorithm obviates the tedium of the manual manipulations involved when the algebraic equations method is used instead. Further, the algorithm provides values at a new design optimization point having attractive kinematic features hitherto not obtained.

Velocity fluctuation in spatial slider crank mechanisms

Abstract Velocity fluctuations have been recognized as important in the statics and dynamics of mechanisms [1]. The geometric conditions governing the existence of extreme velocity ratios in a spatial 4-link mechanism having two revolute, one cylindrical and one prismatic pair have been obtained. The present investigation presents an algebriac solution of the velocity fluctuation problem. It is shown that, in the general case, the extreme velocity ratios must be among the real roots of an 8th degree polynomial in gemometric parameters of the mechanism. The extreme velocity ratios of any given mechanism can be obtained from the above results. Numerical example is presented to illustrate the procedure. The results presented in this paper can be extended to synthesize a spatial four link mechanism with prescribed extreme velocity ratios.