Identification of mechanical parameters at low velocities for a micropositioning stage using a velocity hysteresis model

The paper presents a velocity hysteresis friction model. This model can be used for simulation or control of an accurate micropositioning servomechanism. The mechanical and friction parameters are identified from measured signals at low velocities, and with the use of a closed loop identification method. The measured signals are very noised. The number of measurement samples available is very low. The friction model dépends on position, velocity and acceleration and includes the Coulomb, Stribeck and viscous frictions. A hystérésis effect integrated by an exponential term and the acceleration is added in the model. The identified parameters are validated by applying an efficient precision method based on the sensitivity analysis of nonlinear models and a normalized mean-square-error criterion.AN

Identification of the Servomechanism used for micro-displacement

Friction causes important errors in the control of small servomechanism and should be determined with precision in order to increase the system performance. This paper describes the method to identify the model parameters of a small linear drive with ball-screw. Two kinds of friction models will be applied for the servomechanism looking to rise its micropositioning abilities. The first one includes the static, viscous and Stribeck friction with hysteresis, and the second one uses the Lugre model. The results will be compared taking into account the criterion error, the accuracy and the normalized mean-square-error of the identified mechanical parameters. The coefficients of the models are identified by a recursive identification method using data acquisition and special filtering technics. The least square identification method is used in this paper in order to establish the motor parameters used as initial condition of the recursive estimation method. Computer simulations and experimental results demonstrate the efficiency of the proposed model

Identification of mechanical parameters at low velocities for a micropositioning stage using a velocity hysteresis model

The paper presents a velocity hysteresis friction model. This model can be used for simulation or control of an accurate micropositioning servomechanism. The mechanical and friction parameters are identified from measured signals at low velocities, and with the use of a closed loop identification method. The measured signals are very noised. The number of measurement samples available is very low. The friction model dépends on position, velocity and acceleration and includes the Coulomb, Stribeck and viscous frictions. A hystérésis effect integrated by an exponential term and the acceleration is added in the model. The identified parameters are validated by applying an efficient precision method based on the sensitivity analysis of nonlinear models and a normalized mean-square-error criterion.AN

Modélisation phénoménologique et identification d'un système de micro-positionnement

Les phénomènes de frottement sont à l'origine d'erreurs de positionnement importantes des servo-mécanismes. Une modélisation précise permet de compenser leur effet dans le but d'augmenter les performances du système. Cet article propose une modélisation phénoménologique d'un axe linéaire avec transmission par vis à billes et l'identification des paramètres du modèle par un algorithme d'optimisation. Trois modèles de frottement sont considérés pour le servo-mécanisme. Le premier modèle considère le frottement statique, le frottement visqueux et le frottement de Stribeck avec l'hystérésis. Le deuxième utilise le modèle de Dahl, et le troisième le modèle LuGre. Ces modèles sont non-linéaires en les paramètres. Le critère d'optimisation est déterminé par simulation et considère l'erreur normalisée du couple de commande. Les résultats des trois modèles de frottement sont comparés aux données mesurées. Les simulations et les résultats expérimentaux montrent la validité du modèle proposé

Identification of the Servomechanism used for micro-displacement

Friction causes important errors in the control of small servomechanism and should be determined with precision in order to increase the system performance. This paper describes the method to identify the model parameters of a small linear drive with ball-screw. Two kinds of friction models will be applied for the servomechanism looking to rise its micropositioning abilities. The first one includes the static, viscous and Stribeck friction with hysteresis, and the second one uses the Lugre model. The results will be compared taking into account the criterion error, the accuracy and the normalized mean-square-error of the identified mechanical parameters. The coefficients of the models are identified by a recursive identification method using data acquisition and special filtering technics. The least square identification method is used in this paper in order to establish the motor parameters used as initial condition of the recursive estimation method. Computer simulations and experimental results demonstrate the efficiency of the proposed model

Educación intercultural: propuesta de intervención en un aula de educación infantil

Este Trabajo Fin de Grado (TFG) tiene el propósito de crear una propuesta educativa que pretende señalar la importancia de la Educación Intercultural dentro de las aulas de Educación Infantil a través de la programación y diseño de una serie de actividades. Actualmente vivimos en una sociedad con una gran diversidad cultural, por lo que resulta oportuno y necesario trabajar la Educación Intercultural desde edades tempranas. Esta propuesta está pensada para el CRA El Encinar, colegio de La Losa, en la provincia de Segovia, ubicado concretamente para el aula de 5-6 años, con un total de 13 niños y niñas, en la que nos encontramos un niño de Rumanía, otro de Bulgaria y una niña de Marruecos y el resto de nacionalidad española. Se pretende así que el programa de actividades pueda ser útil para trabajar y fomentar la interculturalidad y hacer partícipes a todos los niños y niñas, y a la vez contar con el apoyo de los familiares.Departamento de Sociología y Trabajo SocialGrado en Educación Infanti

Morphological investigation of calcium phosphates electrodeposited on Ti in the presence of tartaric acid

The electrochemical deposition method was employed to deposit calcium phosphates on Ti substrates in the presence of different concentrations of tartaric acid. Scanning electron microscopy was used to investigate the morphology of the obtained specimens. The micrographs indicate that as the tartaric acid concentration increases, the size and number of calcium phosphate irregular structures increases as well. At the highest concentration a new morphology is evidenced, represented by flat ordered structures with high aspect ratio