Departamento de Ingeniería Electromecánicahttp://hdl.handle.net/10259/42662024-03-29T11:00:26Z2024-03-29T11:00:26ZExperimental study and geometrical method to design bio-inspired robotic kinematic chains of inching-locomotion caterpillarsCornejo, JoséSierra Garcia, Jesús EnriqueGómez Gil, Francisco JavierGrados, JuanPalomares, RicardoWeitzenfeld, Alfredohttp://hdl.handle.net/10259/84112024-01-24T01:05:13Z2024-01-01T00:00:00ZExperimental study and geometrical method to design bio-inspired robotic kinematic chains of inching-locomotion caterpillars
Cornejo, José; Sierra Garcia, Jesús Enrique; Gómez Gil, Francisco Javier; Grados, Juan; Palomares, Ricardo; Weitzenfeld, Alfredo
Inching-locomotion caterpillars (ILAR) show impressive environmental adaptation, having high dexterity and flexibility. To design robots that mimic these abilities, a novel Bioinspired Robotic Design (BIROD) method is presented. The method is composed by an algorithm for Geometrical Kinematic Analysis (GEKINS) to standardize the proportional dimensions according to the insect’s anatomy and obtain the kinematic chains. The approach is experimentally applied to analyze the locomotion and kinematic chain of these specimens: Geometridae – 2 pair of prolegs (represents 35,000 species) and Plusiinae – 3 pair of prolegs (represents 400 species). The obtained data indicate that the application of the proposed method permits to locate the attachment mechanisms, joints, links, and to calculate angular displacement, angular average velocity, number of degrees of freedom, and thus the kinematic chain. Geometridae in contrast to Plusiinae, shows a longer Walk-Stride Length (WSL), a lower number of single-rotational joints in 2-D (3 DOF versus 4 DOF), and a lower number of dual-rotational joints in 3-D (6 DOF versus 8 DOF). The application of BIROD and GEKINS provides the forward kinematics for 35,400 ILAR species and are expected to be useful as a preliminary phase for the design of bio-inspired arthropod robots.
2024-01-01T00:00:00ZFractional viscoelastic models for the estimation of the frequency response of rubber bushings based on relaxation testsCalaf Chica, JoséCea González, VíctorGarcía Tárrago, María JoséGómez Gil, Francisco Javierhttp://hdl.handle.net/10259/83022024-01-12T01:05:24Z2023-10-01T00:00:00ZFractional viscoelastic models for the estimation of the frequency response of rubber bushings based on relaxation tests
Calaf Chica, José; Cea González, Víctor; García Tárrago, María José; Gómez Gil, Francisco Javier
Estimation of the viscoelastic properties of rubber bushings at very high frequencies (up to 2 kHz) is a challenge
for many damping component manufacturers in the design stage of a quality monitoring procedure. This
investigation is focused on the capability of lower strain rate testing procedures, such as relaxation tests, to
estimate and extrapolate the dynamic behavior of rubber bushings from low to moderate frequencies. Fractional
Zener models are employed to approach bushing behavior in experimental relaxation tests, thus leading to
a linear viscoelastic model which is employed to estimate the dynamic behavior of rubber bushing under
harmonics loads up to 150 Hz. The validation of this extrapolation procedure is performed by comparing these
analytical results with experimental dynamic harmonic tests applied to the same rubber bushings. The deviation
between both curves demonstrates that it is difficult to compare the behavior from very small deformation rates
(relaxation tests) to higher deformation rates (harmonic dynamic tests) due to the nonlinear behavior of the
rubber and its amplitude dependence. However, this investigation demonstrates that the relaxation tests contain
enough data to define the frequency behavior of linear viscoelastic materials up to moderate frequencies
2023-10-01T00:00:00ZEstudio de la fiabilidad de test multirrespuesta con el método de Monte CarloCalaf Chica, JoséGarcía Tárrago, María Joséhttp://hdl.handle.net/10259/83012024-01-12T01:05:21Z2021-01-01T00:00:00ZEstudio de la fiabilidad de test multirrespuesta con el método de Monte Carlo
Calaf Chica, José; García Tárrago, María José
Durante gran parte del siglo XX se ha escrito mucho sobre la fiabilidad de los test multirrespuesta como método para la evaluación de contenidos. En concreto son muchos los estudios teóricos y empíricos que buscan enfrentar los distintos sistemas de puntuación existentes. En esta investigación se ha diseñado un algoritmo que genera estudiantes virtuales con los siguientes atributos: conocimiento real, nivel de cautela y conocimiento erróneo. El primer parámetro establece la probabilidad que tiene el alumno de conocer la veracidad o falsedad de cada opción de respuesta del test. El nivel de cautela refleja la probabilidad de responder a una cuestión desconocida. Finalmente, el conocimiento erróneo es aquel conocimiento falsamente asimilado como cierto. El algoritmo también tiene en cuenta parámetros de configuración del test como el número de preguntas, el número de opciones de respuesta por pregunta y el sistema de puntuación establecido. El algoritmo lanza test a los individuos virtuales analizando la desviación generada entre el conocimiento real y el conocimiento estimado (la puntuación alcanzada en el test). En este estudio se confrontaron los sistemas de puntuación más comúnmente utilizados (marcado positivo, marcado negativo, test de elección libre y método de la respuesta doble) para comprobar la fiabilidad de cada uno de ellos. Para la validación del algoritmo, se comparó con un modelo analítico probabilístico. De los resultados obtenidos, se observó que la existencia o no de conocimiento erróneo generaba una importante alteración en la fiabilidad de los test más aceptados por la comunidad educativa (los test de marcado negativo). Ante la imposibilidad de comprobar la existencia de conocimiento erróneo en los individuos a través de un test, es decisión del evaluador castigar su presencia con el uso del marcado negativo, o buscar una estimación más real del conocimiento real a través del marcado positivo.; During the twentieth century many investigations have been published about the reliability of the multiple-choice tests for subject evaluation. Specifically, there are a lot of theoretical and empirical studies that compare the different scoring methods applied in tests. A novel algorithm was designed to generate hypothetical examinees with three specific characteristics: real knowledge, level of cautiousness and erroneous knowledge. The first one established the probability to know the veracity or falsity of each answer choice in a multiple-choice test. The cautiousness level showed the probability to answer an unknown question by guessing. Finally, the erroneous knowledge was false knowledge assimilated as true. The test setup needed by the algorithm included the test length, choices per question and the scoring system. The algorithm launched tests to these hypothetical examinees analysing the deviation between the real knowledge and the estimated knowledge (the test score). The most popular test scoring methods (positive marking, negative marking, free-choice tests and the dual response method) were analysed and compared to measure their reliability. In order to validate the algorithm, this was compared with an analytical probabilistic model. This investigation verified that the presence of the erroneous knowledge generates an important alteration in the reliability of the most accepted scoring methods in the educational community (the negative marking method). In view of the impossibility of ascertaining the existence of erroneous knowledge in the examinees using a test, the examiner could penalize its presence with the use of negative marking, or looking for a best fitted estimation of the real knowledge with the positive marking method.
2021-01-01T00:00:00ZCold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered MandrelsCurto Cárdenas, DavidCalaf Chica, JoséBravo Díez, Pedro MiguelPreciado Calzada, MónicaGarcía Tárrago, María Joséhttp://hdl.handle.net/10259/83002024-01-12T01:05:29Z2020-12-01T00:00:00ZCold Expansion Process with Multiple Balls—Numerical Simulation and Comparison with Single Ball and Tapered Mandrels
Curto Cárdenas, David; Calaf Chica, José; Bravo Díez, Pedro Miguel; Preciado Calzada, Mónica; García Tárrago, María José
Cold expansion technology is an extended method used in aeronautics to increase fatigue
life of holes and hence extending inspection intervals. During the cold expansion process, a mechanical
mandrel is forced to pass along the hole generating compressive residual hoop stresses. The most
widely accepted geometry for this mandrel is the tapered one and simpler options like balls have
generally been rejected based on the non-conforming residual hoop stresses derived from their use.
In this investigation a novelty process using multiple balls with incremental interference, instead
of a single one, was simulated. Experimental tests were performed to validate the finite element
method (FEM) models and residual hoop stresses from multiple balls simulation were compared with
one ball and tapered mandrel simulations. Results showed that the use of three incremental balls
significantly reduced the magnitude of non-conforming residual hoop stresses and the extension of
these detrimental zone.
2020-12-01T00:00:00Z