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Improve a 3D distance measurement accuracy in stereo vision systems using optimization methods’ approach

Rodríguez-Quiñonez J. C., Sergiyenko O., Flores-Fuentes W., Rivas-lopez M., Hernandez-Balbuena D., Rascón R., Mercorelli P.

Opto-Electronics Review

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2017

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Vol. 25, No. 1

24--32

EN

This paper presents a 3D distance measurement accuracy improvement for stereo vision systems using optimization methods A Stereo Vision system is developed and tested to identify common uncertainty sources. As the optimization methods are used to train a neural network, the resulting equation can be implemented in real time stereo vision systems. Computational experiments and a comparative analysis are conducted to identify a training function with a minimal error performance for such method. The offered method provides a general purpose modelling technique, attending diverse problems that affect stereo vision systems. Finally, the proposed method is applied in the developed stereo vision system and a statistical analysis is performed to validate the obtained improvements.

2

A New Approach to Measurement of Frequency Shifts Using the Principle of Rational Approximations

Murrieta-Rico F. N., Petranovskii V., Sergiyenko O. Y., Hernandez-Balbuena D., Lindner L.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 1

45--56

EN

When a frequency domain sensor is under the effect of an input stimulus, there is a frequency shift at its output. One of the most important advantages of such sensors is their converting a physical input parameter into time variations. In consequence, changes of an input stimulus can be quantified very precisely, provided that a proper frequency counter/meter is used. Unfortunately, it is well known in the time-frequency metrology that if a higher accuracy in measurements is needed, a longer time for measuring is required. The principle of rational approximations is a method to measure a signal frequency. One of its main properties is that the time required for measuring decreases when the order of an unknown frequency increases. In particular, this work shows a new measurement technique, which is devoted to measuring the frequency shifts that occur in frequency domain sensors. The presented research result is a modification of the principle of rational approximations. In this work a mathematical analysis is presented, and the theory of this new measurement method is analysed in detail. As a result, a new formalism for frequency measurement is proposed, which improves resolution and reduces the measurement time.

3

Regulation control of an underactuated mechanical system with discontinuous friction and backlash

Rascón R., Rosas D., Hernandez-Balbuena D.

International Journal of Applied Mathematics and Computer Science

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2017

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Vol. 27, no. 4

785--797

EN

In this work, the problem of position regulation control is addressed for a 2DOF underactuated mechanical system with friction and backlash. For this purpose, a method combining sliding mode and H∞ control is developed. We prove that the application of the method to the nonlinear model considered results in an asymptotically stable equilibria set. Moreover, it is possible to achieve a sufficiently small and bounded steady-state position error even in the presence of disturbances by employing the proposed technique. That is, the developed controller is able to account not only for unmatched external perturbations and model discrepancies of the test rig considered, but also for matched bounded perturbations. The control methodology is presented from both the theoretical and experimental angles to demonstrate the good performance of the proposed controller.

4

Improve 3D laser scanner measurements accuracy using a FFBP neural network with Widrow-Hoff weight/bias learning function

Rodríguez-Quiňonez J. C., Sergiyenko O., Hernandez-Balbuena D., Rivas-Lopez M., Flores-Fuentes W., Basaca-Preciado L. C.

Opto-Electronics Review

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2014

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Vol. 22, No. 4

224-235

EN

Many laser scanners depend on their mechanical construction to guarantee their measurements accuracy, however, the current computational technologies allow us to improve these measurements by mathematical methods implemented in neural networks. In this article we are going to introduce the current laser scanner technologies, give a description of our 3D laser scanner and adjust their measurement error by a previously trained feed forward back propagation (FFBP) neural network with a Widrow-Hoff weight/bias learning function. A comparative analysis with other learning functions such as the Kohonen algorithm and gradient descendent with momentum algorithm is presented. Finally, computational simulations are conducted to verify the performance and method uncertainty in the proposed system.