Acosta P.R.,Chihuahua Institute of Technology
Mathematical Problems in Engineering | Year: 2013
This paper deals with a class of second order sliding mode systems. Based on the derivative of the sliding surface, sufficient conditions are given for stability. However, the discontinuous control signal depend neither on the derivative of sliding surface nor on its estimate. Time delay in control input is also an important issue in sliding mode control for engineering applications. Therefore, also sufficient conditions are given for the time delay size on the discontinuous input signal, so that this class of second order sliding mode systems might have amplitude bounded oscillations. Moreover, amplitude of such oscillations may be estimated. Some numerical examples are given to validate the results. At the end, some conclusions are given on the possibilities of the results as well as their limitations. © 2013 Pedro R. Acosta.
Acosta-Cano J.,Chihuahua Institute of Technology |
Sastron-Baguena F.,Technical University of Madrid
Journal of Applied Research and Technology | Year: 2013
Coupling shop floor software system (SFS) with the set of production equipment (SPE) becomes a complex task. It involves open and proprietary standards, information and communication technologies among other tools and techniques. Due to market turbulence, either custom solutions or standards based solutions eventually require a considerable effort of adaptation. Loose coupling concept has been identified in the organizational design community as a compensator for organization survival. Its presence reduces organization reaction to environment changes. In this paper the results obtained by the organizational design community are identified, translated and organized to support the SFS-SPE integration problem solution. A classical loose coupling model developed by organizational studies community is abstracted and translated to the area of interest. Key aspects are identified to be used as promoters of SFS-SPE loose coupling and presented in a form of a reference scheme. Furthermore, this reference scheme is proposed here as a basis for the design and implementation of a generic coupling solution or coupling framework, that is included as a loose coupling stage between SFS and SPE. A validation example with various sets of manufacturing equipment, using different physical communication media, controller commands, programming languages and wire protocols is presented, showing an acceptable level of autonomy gained by the SFS.
Maldonado A.,Autonomous University of Ciudad Juarez |
Maldonado A.,Chihuahua Institute of Technology |
Garcia J.L.,Autonomous University of Ciudad Juarez |
Alvarado A.,Autonomous University of Ciudad Juarez |
Balderrama C.O.,Autonomous University of Ciudad Juarez
International Journal of Advanced Manufacturing Technology | Year: 2013
Advanced manufacturing technology (AMT) is a relevant resource that has been extensively used in modern industries around the world with the aim of being competitive and maintaining high levels of quality and performance. There is a wide variety of tools and models available in the literature to support AMT selection and evaluation processes. Usually, they consist of analyses of tangible aspects, such as cost, time, speed, precision, among others; however, some other important aspects are commonly neglected, that is, the case of human factors and ergonomic characteristics. This paper presents a new methodology for the evaluation of ergonomic compatibility of AMT. This methodology may be considered as a decision aid; thus, decision makers might perform their duties in a more complete manner taking into account ergonomic attributes. Fuzzy axiomatic design applications are state of the art methods for decision making, and this paper contributes with a unique application for ergonomic compatibility evaluation for AMT. The first part of the paper presents the findings of an extensive literature review about important ergonomic attributes of AMT. Then, those attributes were originally structured following a multi-attribute axiomatic design approach for AMT ergonomic evaluation under a fuzzy environment. Also, a unique ergonomic compatibility survey was proposed for data collection and an original procedure was developed for AMT evaluation, a numerical example is provided. The ergonomic compatibility concept was tested and validated using the Cronbach's alpha test (α ≥ 0.7), finding that the instrument is suitable for the measurement of the proposed construct. © 2012 Springer-Verlag London Limited.
Acosta P.,Chihuahua Institute of Technology
Journal of the Franklin Institute | Year: 2014
It is well known that sliding mode control is based on the definition of an invariant manifold, where the system dynamics are forced to in a finite time. Such a manifold is somewhat arbitrarily defined, as long as the system dynamics are stable on it. Computational and control effort may vary depending on selected manifold. Obviously, if a system has naturally acceptable stable dynamics around a desired equilibrium point, no control is needed unless uncertainties or disturbances are present. It would be desirable that if such a system had uncertainties or disturbances, the control effort be designed only to overcome the effect of such factors. For a system with first order dynamics and affine control input, designing a sliding mode control overcoming only such uncertainties or disturbances is a trivial task. When a higher order dynamics system is involved, unit control may be used, where the input control signals are not discontinuous, but when only discontinuous control inputs are available, a design approach is not readily available. In this paper, taking advantage of the natural stable dynamics of a system, a sliding mode control approach is introduced for designing multiple discontinuous control inputs, where the control effort overcomes only uncertainties, disturbances or unstable dynamics. Two illustrative examples are given in order to show the feasibility of the method. © 2014 The Franklin Institute.
Ramirez-Alonso G.,Chihuahua Institute of Technology |
Chacon-Murguia M.I.,Chihuahua Institute of Technology
Neurocomputing | Year: 2016
This paper presents a new Background Subtraction System scheme based on two Self Organized Maps (SOM) that adapt in a parallel way at different rates. Our system can automatically identify the possible issue that mainly affects the performance of the video segmentation model (such as dynamic/static background, stationary dynamic objects, jittering camera, camouflage, etc.,) by analyzing the initial frames of the video sequence. Four different modules are implemented to treat separately all these situations and different analysis are performed on them. Our system maintains a high adaptive capability in all the video sequence analysis, it is not restricted to only the initial frames of the sequence as most segmentation algorithms. In our Auto-Adaptive Parallel SOM Architecture, AAPSA, a Suspicious Foreground analysis is constantly monitoring the segmentation results in order to obtain a reduction on the false positive rates. AAPSA was validated with Change Detection 2014 and BMC databases by using the same initial model parameters on both databases demonstrating its robustness with different and complicated scenarios. In order to simulate the videos that a security guard must analyze, 3 sequences were created by concatenated videos from AVSS, PETS2001 and Change Detection. The segmentation results obtained demonstrate that our system produced the best definition of dynamic objects compared with State of the Art models. © 2015 Elsevier B.V.