Papers by Jesús cervantes
Esta contribucion presenta las herramientas necesarias para la determinacion de los coeficientes ... more Esta contribucion presenta las herramientas necesarias para la determinacion de los coeficientes geometricos de resistencia y durabilidad para engranes rectos estandar y no-estandar. Este es un tema interdisciplinario que requiere conocimientos de la cinematica de las maquinas ---en particular de la interaccion entre dos engranes cuyo perfil corresponde a la curva involuta de un circulo--- y diseno de elementos mecanicos. Como un resultado adicional, el analisis permite determinar de manera precisa el perfil de los dientes de engrane para diferentes tipos de cortadores y analizar de manera muy intuitiva el fenomeno de socavamiento.
Esta contribucion presenta la solucion del analisis dinamico inverso de un mecanismo plano de cua... more Esta contribucion presenta la solucion del analisis dinamico inverso de un mecanismo plano de cuatro barras; es decir ---conocidas las dimensiones, propiedades masicas e inerciales de los eslabones de un mecanismo y las fuerzas externas aplicadas al mismo--- determinar el movimiento del mecanismo. La contribucion presenta la deduccion de la ecuacion diferencial, altamente no lineal, que rige el analisis dinamico inverso del mecanismo, su conversion a un sistema de ecuaciones diferenciales algebraicas, su solucion numerica empleando el programa de matematica simbolica Maple™ y la comparacion, satisfactoria, de estos resultados con los obtenidos mediante el programa de simulacion Adams™.
Journal of Mechanisms and Robotics, 2016
The method of intersection of surfaces generated by kinematic dyads is applied to obtain mechanis... more The method of intersection of surfaces generated by kinematic dyads is applied to obtain mechanisms that are able to shift from one mode of motion to another. Then a mobility analysis shows that the singularities of the generated surfaces can be used to obtain mechanisms which can change their number of degrees-of-freedom depending on its configuration. The generator dyads are connected as usually done by a spherical pair. However, in the cases shown in this contribution the three-degrees-of-freedom of the spherical pair are not all necessary to keep the kinematic chain closed and movable, and the spherical pair can be substituted by either a pair of intersecting revolute joints or a single revolute joint. This substitution can be obtained by means of two methods presented in this contribution.
Volume 6: 35th Mechanisms and Robotics Conference, Parts A and B, 2011
This contribution presents further properties of screw systems generated from the sum of subalgeb... more This contribution presents further properties of screw systems generated from the sum of subalgebras of the Lie algebra, se(3), of the Euclidean group, SE(3). In particular, it is shown that they exhibit the property of having a locally constant rank. This property has been used, without proper formalization, in the design of parallel platforms. In addition, since the order of screws in a screw system — and therefore the order of their corresponding kinematic pairs within the kinematic chain that realize the screw system — is shown to be decisive for fulfilling the property of having a locally constant rank, the name screw systems may be not at all appropriate.
Volume 2: 34th Annual Mechanisms and Robotics Conference, Parts A and B, 2010
This paper presents some experiences on the teaching of kinematics and robotics in Mexican univer... more This paper presents some experiences on the teaching of kinematics and robotics in Mexican universities. A short sociological background information together with generalities about the curricula of mechanical and mechatronics engineers is shown. After that, the contents of two courses Mechanisms and Robotics are presented in detail. Finally, three unrelated examples of learning aids design and the introduction of more advanced mathematical tools to the study of kinematics of machinery and robotics are discussed. Nevertheless, the examples show the effort to overcome some of the deficiencies of our incoming engineering students.Copyright © 2010 by ASME
Volume 8: 31st Mechanisms and Robotics Conference, Parts A and B, 2007
Setting aside paradoxical linkages such as Bennett’s, Bricard’s or Goldberg’s, the mobility of si... more Setting aside paradoxical linkages such as Bennett’s, Bricard’s or Goldberg’s, the mobility of single loop linkages seemed, with the developments on mobility analysis carried out in the last five years, a closed chapter in kinematic research. However, recent developments on the mobility of parallel platforms have shed additional insight into the problem. This contribution attempts to unify the results obtained in the last five years in the area of mobility of single-loop kinematic chains to state what appears to be a final word on the subject.
Advances in Robot Kinematics, 2002
An R-S-S-R spatial four-bar mechanism provides a revolute actuated one dof platform attached to t... more An R-S-S-R spatial four-bar mechanism provides a revolute actuated one dof platform attached to the S-S coupler with a third C-S leg. All three spherical joints are on the platform. This mechanism may have eight real, distinct assembly modes but the solution reduces to a univariate quartic equation which arises from the coplanar intersection of a circle and an ellipse. This input-output analysis is the direct kinematics(DKP) of three legged, six degree of freedom parallel platforms with 3-2-1 basal actuation and up to eight assemblies.
Recent Advances in Integrated Design and Manufacturing in Mechanical Engineering, 2003
In this paper we develop an as-yet-missing theoretical framework as well as a general methodology... more In this paper we develop an as-yet-missing theoretical framework as well as a general methodology for model-based robust design. At the outset, a distinction is made between three sets: the set of design variables, grouped in the n-dimensional vector x, which are to be assigned values as an outcome of the design job; the set of design-environment parameters (DEP), grouped in the v-dimensional vector p, over which the designer has no control; and the set of performance functions, arrayed in the m-dimensional vector f, representing the functional relations among performance, design variables and DEP. Resorting to the mathematical model available for the object under design, an m × v design performance matrix F, mapping the space of relative variations of p into that of relative variations of f, is derived. Moreover, two pertinent concepts are introduced: the design sensitivity matrix, which plays a major role in the transmission of the variations of p into variations off, and its associated bandwidth, defined as the logarithm of the square root of the ratio between the maximum to the minimum singular values of the design performance matrix, measured in decades. A result stating the relation between the bandwidth of a matrix and its inverse is shown. Consequently, the aforementioned bandwidth represents an index for evaluating the robustness of a design. To demonstrate our approach, case studies are included
Robotics and Computer-Integrated Manufacturing, 2003
A vision-based control methodology is presented in this paper that can perform accurate, three-di... more A vision-based control methodology is presented in this paper that can perform accurate, three-dimensional (3D), positioning and path-tracking tasks. Tested with the challenging manufacturing task of welding in an unstructured environment, the proposed methodology has proven to be highly reliable, consistently achieving terminal precision of 1 mm: A key limiting factor for this high precision is camera-space resolution per unit physical space. This paper also presents a means of preserving and even increasing this ratio over a large region of the robot's workspace by using data from multiple vision sensors. In the experiments reported in this paper, a laser is used to facilitate the image processing aspect of the vision-based control strategy. The laser projects ''laser spots'' over the workpiece in order to gather information about the workpiece geometry. Previous applications of the control method were limited to considering only local, geometric information of the workpiece, close to the region where the robot's tool is going to be placed. This paper presents a methodology to consider all available information about the geometry of the workpiece. This data is represented in a compact matrix format that is used within the algorithm to evaluate an optimal robot configuration. The proposed strategy processes and stores the information that comes from various vision sensors in an efficient manner. An important goal of the proposed methodology is to facilitate the use of industrial robots in unstructured environments. A graphical-user-interface (GUI) has been developed that simplifies the use of the robot/vision system. With this GUI, complex tasks such as welding can be successfully performed by users with limited experience in the control of robots and welding techniques.
En este trabajo se presenta una metodologia para simular el fenomeno vibratorio asociado con el m... more En este trabajo se presenta una metodologia para simular el fenomeno vibratorio asociado con el movimiento de una barra sobre un plano vertical. Se muestran algunas graficas de la respuesta del sistema con diferentes parametros mecanicos.
Volume 7: 46th Mechanisms and Robotics Conference (MR)
This paper presents a unified approach for the determination of the instantaneous screw axes for ... more This paper presents a unified approach for the determination of the instantaneous screw axes for one-DOF linkages associated with the different subgroups of the Euclidean group. The theory behind the approach is based on the most general form of the three-axes theorem and the invariant symmetric forms, Killing and Klein, defined on se(3), the Lie algebra of the Euclidean group, SE (3). Using the Killing and Klein forms on the general form of the three-axes theorem provides sufficient equations to find the instantaneous screw axes of any linkage. The contribution provides a unified approach for the determination of the instantaneous screw axis associated with the relative motion of two bodies in general spatial motion. Further, the equations can be simplified when considering the different subalgebras of the Lie algebra of the Euclidean group, in particular, the spherical and planar subalgebras. The contribution includes two subgroups (subalgebras) that have not been previously analy...
Robotica, 2015
SUMMARYThis paper presents a systematic approach to compute the angularity and the axiality indic... more SUMMARYThis paper presents a systematic approach to compute the angularity and the axiality indices for a Schönflies parallel manipulator. Angularity index may be considered as a measure of the sensitivity of the mobile platform to changes in rotation, while axiality index can be used to measure the sensitivity of the OP of the mobile platform to changes in translation. Since both indices were inspired by very fundamental concepts of classical kinematics (angular velocity vector and helicoidal velocity field), they offer a clear and simple physical meaning, which may be useful to the designer of parallel manipulators. Moreover, both dexterity indices do not require obtaining a dimensionally homogeneous Jacobian matrix, nor do they depend on having similar types of actuators in each manipulator's leg. Detailed numerical examples are given in order to illustrate the computation of the dexterity indices.
Journal of Mechanical Design
Classical dynamic balancing techniques do not consider the linkage elastic behavior. For mechanis... more Classical dynamic balancing techniques do not consider the linkage elastic behavior. For mechanism or robot design purpose, taking into account the flexibility of the multibody system is of utmost importance, in order to be able to manufacture a mechanism/robot which is stiff enough for a given task. This paper deals with a novel approach that allows to design mechanisms by means of structural topology optimization while specific dynamic balancing conditions are considered. In our work, the links are treated as three-dimensional flexible bodies, and the optimization process is performed for all the bodies simultaneously. Applying this methodology, the optimal design of a dynamically balanced four-bar linkage is accomplished while its compliance is minimized. Numerical validations of the optimized linkage properties are carried out using commercial software. The dynamic balancing performance of the optimized four-bar linkage is numerically validated using adams. Besides, ansys softwa...
Mechanics Based Design of Structures and Machines, 2020
This paper presents a screw theory approach for the computation of the instantaneous rotation axe... more This paper presents a screw theory approach for the computation of the instantaneous rotation axes of indeterminate spherical linkages. Since the last part of the XIX century, the determination of the instantaneous rotation, or velocity, centers of planar mechanisms has been studied using the Aronhold-Kennedy theorem, extended to the spatial case until the second part of last century. In the beginning of the XX century, it was found that there were planar mechanisms for which the application of the Aronhold-Kennedy theorem was unable to find all the instantaneous rotation centers; these mechanisms where denominated complex or indeterminate. The beginning of this century saw a renewed interest on the complex or indeterminate mechanisms, both planar and spherical; and very soon, taken advantage of the results obtained for planar mechanisms, there were several methods for the determination of the indeterminate instantaneous rotation axes. The new screw theory approach, presented here, provides a more straightforward method for setting up the equations; furthermore, the algebraic equations to be solved are simpler than the ones published up to date. In addition, the method is part of a comprehensive method for the determination of the instantaneous screw axes of spatial mechanisms or their many special cases. The method is based on a systematic application of screw theory, which is isomorphic to the Lie algebra, se(3), of the Euclidean group, SE(3), and the invariant symmetric bilinear forms defined on se(3).
Journal of Mechanisms and Robotics, 2021
This contribution presents a screw theory-based method for determining the mobility of fully para... more This contribution presents a screw theory-based method for determining the mobility of fully parallel platforms. The method is based on the application of three stages. The first stage involves the application of the intersection of subalgebras of Lie algebra, se(3), of the special Euclidean group, SE(3), associated with the legs of the platform. The second stage analyzes the possibility of the legs of the platform generating a sum or direct sum of two subalgebras of the Lie algebra, se(3). The last stage, if necessary, considers the possibility of the kinematic pairs of the legs satisfying certain velocity conditions; these conditions reduce the platform’s mobility analysis to one that can be solved using one of the two previous stages. Several examples are illustrated.
Volume 5B: 43rd Mechanisms and Robotics Conference, 2019
This paper analyzes the well known three axes theorem under the light of the Lie algebra se(3) of... more This paper analyzes the well known three axes theorem under the light of the Lie algebra se(3) of the Euclidean group, SE(3) and the symmetric bilinear forms that can be defined in this algebra. After a brief historical review of the Aronhold-Kennedy theorem and its spatial generalization, the main hypothesis is that the general version of the Aronhold-Kennedy theorem is basically the application of the Killing and Klein forms to the equation that relates the velocity states of three bodies regardless if they are free to move in the space, independent of each other, or they form part of a kinematic chain. Two representative examples are employed to illustrate the hypothesis, one where the rigid bodies are free to move in the space without any connections among them and other concerning a RCCC spatial mechanism.
This contribution provides new definitions of infinitesimal mobility and connectivity of kinemati... more This contribution provides new definitions of infinitesimal mobility and connectivity of kinematic chains. These definitions are straightforwardly connected with accepted definitions of finite mobility and connectivity. Further, screw theory is applied to the determination of the infinitesimal mobility and connectivity of multi-loop linkages. These results provide a guide for the determination of the finite mobility and connectivity of general topology of multiloop linkages, one of the important remaining problems in mobility theory.
Acta Universitaria, 2007
In this paper, we have used commercial software ADAMS© and Matlab© to simulate a rider-bike-track... more In this paper, we have used commercial software ADAMS© and Matlab© to simulate a rider-bike-track in a downhill race. The bike suspension dynamic behavior was analyzed by developing a novel control algorithm denominated MTB for a semi-active suspension model. Nevertheless, the control algorithm is not the only original contribution of this work. Even though the semi-active model has been used in previous projects, to the best of our knowledge they have not included bike, rider and track as variables in the system. We have simulated the control actions the rider has to develop in a race with a specific track, feeding the model with some data from literature and others were obtained by direct measures. We have also included a simulation using the most referenced control algorithm, Skyhook, for semi-active suspension. This was done with the purpose of comparing this algorithm with the performance of our MTB algorithm.
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Papers by Jesús cervantes