Graphical synthesis of a 4-bar mechanismLa synthese graphique d'un mecanisme avec quatre barres

For a mechanism operating at steady state, the synthesis technique for specified coupler point location, velocity and acceleration is developed from the geometric nature of the acceleration pole. Two examples are presented. One example is based on a known site for the acceleration pole and the other depends on locating the pole from a specified acceleration.     

Re-examination of a kempe linkageReexamen d'un mecanisme de kempe

More than a century ago, A. B. Kempe isolated several multiloop planar linkages, provoking considerable interest among mathematicians. Largely forgotten now, his work has not been followed up in the kinematics literature. One particularly fascinating solution lends itself more readilythan others to spatial analogues, but Kempe erred in its determination. Here, we present a fresh analysis of that solution, using an adaptation of closure equation algebra. Further insight is provided by means of some novel geometrical techniques. Attention is also given to the general matter of the mobility of multiloop linkages.     

The effect of link parameter on the working space of general 3R robot armsL'effet d'un parametre d'un accouplement sur l'espace de travail des bras du robot 3R general

This paper will consider a robot into two parts: “regional structure” and “orientational structure”. The regional structure contributes the gross motion of the robot hand, and the orientational structure contributes the orientation of the robot hand. By studying the effects of kinematic parameters on the general 3R robots, the optimum regional structure and the optimum orientational structure are arrived in this paper.     

Four-square sprocket test machineMachine d'essai en boucle ferme pour les roues a chaines

A 4-square sprocket test machine was built to obtain load vs cycle life data for various chain and sprocket geometry and material combinations. Sprockets were evaluated at various rotational speeds and chain loads that provided accelerated failures. Instrumentation on the machine recorded total sprocket cycles and a sensing switch automatically shut-off the machine when a failure occurred in the sprocket-chain system. Failure was defined as the point at which the chain-sprocket system ceased to function normally. In this paper, the 4-square sprocket test machine is described, preliminary load-cycle life results are given, and an SEM study of failed sprockets is presented.     

A note on position analysis of manipulatorsUne note sur l'analyse de la position des manipulateurs

The notion of zero position of a manipulator is introduced and used in conjunction with the principle of similarity to derive analysis equations. The usual link coordinate systems are not defined and the base coordinate system is the only one used in analysis.     

An analysis of goldberg's anconoidal linkageUne analyse du mecanisme anconoidal de Goldberg

Among Goldberg's pioneering works is his introduction of spatial networks of Bennett linkages, inspired partially by Kempe's planar networks. Presented more than 35 yr ago, his innovatory chains have never been correctly nor fully analysed. This paper is intended to remedy that situation and to put Goldberg's multiloop linkages into perspective against related recent advances.     

An adaptive manipulator with force sensorsUn manipulateur adaptif avec des senseurs de force

This paper discusses some capabilities of a manipulator with a three-component force sensor which enables one to solve such problems as extraction of workpieces from “bulk”, object contour tracing, etc. An approach is described providing artificial contrallable stiffness of the manipulator grip which allows one to manipulate with objects under external kinematic links.     

Closed-form analytic synthesis of a five-link spatial motion generatorLa synthese analytique non-iterative d'un generateur de mouvement spatial avec cinq barres

In the synthesis of motion generating mechanisms we seek to determine the key dimensions of a preconceived type of single-degree-of-freedom mechanism which will guide one of its links through a sequence of finitely or infinitesimally separated arbitrarily prescribed positions. In space, each such finitely separated precision position can be specified by the radius vector of the origin and the Euler angles of orientation of a coordinate system, embedded in the guided link, with respect to a fixed coordinate system of reference.The motion generator mechanim considered here consists of two grounded S-S links, ⁵ one grounded C-S link, a ternary S-S-S coupler and the R-R-C fixed frame. Motion of the coupler is to prescribed. Each equation of synthesis is written by expressing the closure of the vector polygon covering the starting and one displaced position of one dyad formed by a grounded link and the coupler. The resulting system can be solved for unknown vectors defining the dyad in its starting position, in closed form for up to three precision positions.     

Optimizing 4-bar crank-rocker mechanismOptimisation du mecanisme a quatre barres avec une manivelle et un balancier

Closed form equations are developed for the synthesis of the 4-bar crank-rocker mechanism in which the angle between dead-centre positions of the rocker and the corresponding angle turned by the crank are prescribed. All the four different situations are considered and the minimum transmission angle, for the complete rotation of the crank, is obtained for each case. The upper and lower bounds on the crank angle, corresponding to a dead centre position of the rocker, are obtained by using Grashof's criterion. The design is optimized by maximizing the minimum transmission angle. Each case is illustrated by providing a numerical example.     

Synthesis of a mechanism for the stabilisation of a radar antennaSynthèse d'un mécanisme pour la stabilisation d'une antenne de radar

A mechanism designed to stabilise radar antennae on sea-going vessels is analysed geometrically and equations derived which relate the mechanism parameters with the vessel attitude. The analysis is developed to give a method by which configurations of the mechanism may be selected which are compatible with the maximum pitch and roll of the vessel. Further development of the analysis yields a method of synthesis which enables desired kinematic conditions to be achieved. Examples of compatibility and of synthesis are given.     

Three position precessing mechanism synthesisLa synthese d'un mecanisme a preceder en trois positions

This paper presents a complex number development of a three position geared five-bar precessing mechanism synthesis.The methodology which is presented in this study is based on an extension of Burmester cycloidal circlepoint-centerpoint theory[2]. This paper presents the mathematical formulation of the synthesis process.A structured FORTRAN computer program was developed on a VAX 11/780 computer in order to implement the synthesis process. The synthesis program is capable of presenting the synthesis results on a graphical display. Typical results are shown.     

Proportions of rectilinear conchoid linkagesLes proportions d'un mécanisme conchoïde pour la génération d'un mouvement rectiligne

A conchoidal linkage is considered in which the movement of an output point is almost straight and almost proportional to the rotation of an input crank. A general method of finding how the departures from straightness and proportionality depend on the proportions of the linkage is applied to producing design curves that show the proportions giving the smallest errors for a given movement and the greatest movement for given errors. Both straightness and proportionality can be better than previous investigations have suggested.     

On the analyses of sprocket load distributionAnalyse de la distribution des charges dans les roues dentees

This paper presents a spring model analysis for the load distribution in chains and in sprocket teeth and compares the results with those from a traditional force-balance analysis which does not include a consideration of elastic properties.     

The stabilization of the position of the body of walking machinesLa stabilisation de la position du corps d'une machine marchante

This paper shows that in the task of the maintenance of constant orientation of the body of a walking robot the determination of the actual position of the body, i.e. absolute altitudes of its points and remoteness from the supporting surface, is the most complicated problem. Two possible systems of measurement and stabilization of the position by the height of the body of the walking mechanism are compared, i.e. a system of adaptation automatically adjusting the length of the supporting leg to the roughness of the terrain, and the system of the maintenance of constant remoteness of the body from the terrain. The inefficiency of a solitary application of any described system is revealed and the possibility of an accumulation of errors of the position of the body by the walking on the soft terrain is shown. Possible approaches for raising the quality of stabilization of the body by the walking are evaluated.     

Evolutionary adaptation of control processes in robots operating in nonstationary environmentsL'adaptation evolutionnaire des methodes de controle dans les robots fonctionnant dans une ambiance non stationnaire

The paper outlines a new approach to the adaptation problem is nonstationary conditions, the method of evolutionary adaptation, which is characterized by a lack of formalized a priori information about the evolution of the characteristics (parameters) under estimation. The basic philosophy of the approach is in tracking the time varying characteristics on the basis of current information. The two levels (performing and tactical) of the hierarchically organized robots control system are considered and the evolutionary adaptation technique is formulated and developed for each level. The parameters estimation algorithms show the following properties: minimum variance unbiased estimates, recurrent form, on-line time varying parameters identification (ensuring the parameters tracking) and convergence independent of the choice of the estimator initial conditions. The proposed adaptive control scheme may be applied when designing robots operating in an environment essential to the occurrence of nonstationary phase coordinates.     

Intrinsic transmission functions of plane single-loop kinematic chains with revolute or prismatic jointsFonctions de transmission intrinseques d'une chaine cinematique plane a une boucle ayant des joints articules ou a glissiere

Expressions for the intrinsic transmission functions of a plane single-loop kinematic chain, with revolute or translation joints and many degrees of freedom are found using the vector analysis. They are shown to represent a ratio of the oriented areas of triangles, or a combination of such rations for transmission functions of a higher orders. A set of equations is formed which establishes the relation between the intrinsic and absolute transmission functions.     

Application of whitworth quick return mechanism for high velocity impacting pressL'application du mecanisme a retour rapide de whitworth pour une presse d'impact a grande vitesse

The Whitworth quick return mechanism has been modified and used for constructing high-velocity impacting press. The impacting press drive comprises a Whitworth quick return mechanism consisting of a crank and a drive arm together with a variable speed d.c. motor, a flywheel, bearings, etc. The end of the drive arm is attached by a connecting rod to a cycloidal cam. In single cycle operation, the cam is made to engage with an upper platen (or ram) which impacts the workpiece. The upper platen and cam are both mounted on multirod supports with linear ball bushings. A brake is provided on the flywheel for emergency purposes. The high-speed impacting presses are subject to severe dynamic forces when operating at speeds of 200 rpm and greater. Although the mechanism has been designed to withstand operation at higher frequencies, the loads transmitted to the building foundations cause unwanted vibrations and noise. This paper also examines the causes of the unbalanced forces and means to reduce the loads transmitted to the foundations of the high velocity impacting press. An analysis is presented which yields an approximate expression for the angular displacement, velocity and acceleration of the quick return mechanism. Rapid changes in acceleration and high-peak values contribute to the severity of the problem. The bearing reaction forces are determined. Different approaches of this problem have been discussed and analyzed.     

On the optimal design of multi-speed gear trainsConception optimale des trains d'engrenages aux vitesses multiples

An efficient method for analyzing multi-speed gear trains is presented and used in this paper. This new technique obtains equations for the diameters of all the gears used in the transmission based on information contained in the speed diagram. The form of the equations is such that they can be generated by the computer automatically. Further, the equations are applicable to the general arrangement, the single composite arrangements, and the double composite arrangements. As a result, all of the promising kinematic arrangements possible for a given number of speeds can be easily studied. By promoting different constraints and objective functions, trace-offs between different parameters can easily be examined. The technique is illustrated using a case study of a 9 speed gear train. A multi-parameter optimization technique is used to solve 19 different arrangements for a weighted objective function minimizing volume and maximizing stiffness.     

The application of Chace's vector equations to the computer generation of Burmester curvesL'Application des equations vectirielles de chase a la generation par ordinateur des courbes de Burmester

A vector method for the generation of Burmester curves by computer is described. It is based on the graphical method due to L. Burmester and applies Chace's vector equations (Case 1 and Case 3) for solving vector triangles. Stevensen's VECTOR and CHACE subroutine subprograms are used in the computer program. An application of the program to the problem of guiding the boom of a front loader is discussed.     

Conditions for backward synchronous whirl of a flexible rotor in hydrodynamic bearingsConditions pour une precession synchrone retrograde d'un rotor flexible dans les paliers hydrodynamiques

This paper deals with the dynamic unbalance response of a single mass Jeffcott rotor in hydrodynamic bearings. The cross-coupled spring coefficients are considered in the analysis and damping has been neglected. It has been shown that there could be either two distinct critical speeds of the rotor with a backward synchronous whirl between them, or that there is no possible conventional critical speed of the rotor. Two case studies are presented.