A new approach for direct kinematic solution of a soft robotic neck

[Resumen] El mecanismo de cuello robótico presentado en este trabajo tiene como elemento principal un eslabón blando que emula un cuello humano con dos grados de libertad (DOF) (flexión, extensión y flexión lateral). El dispositivo se basa en un Mecanismo Paralelo Accionado por Cable (CDPM). Se desarrolla una cinemática directa a partir del sistema estático y la distribución geométrica del mecanismo, y se presentan ecuaciones lineales que permiten conocer fácilmente la longitud de los cables para hallar la posición del cuello, tanto en ángulos de inclinación como de orientación. Para el control del motor se utiliza un controlador PI de orden fraccionario (FOPI).[Abstract] The robotic neck mechanism presented in this paper has as its main element a soft link that emulates a human neck with two DOF (flexion, extension and lateral bending). The mechanism is based on a Cable-Driven Parallel Mechanism (CDPM). A direct kinematics is developed from the static system and the geometric distribution of the mechanism, and linear equations are presented that relate the length of the cables and the position of the neck, both in inclination and orientation angles. For the motor control, a fractional order PI controller (FOPI) is usedMinisterio de Economia Industria y Competitividad; PID2020-113194GB-I0

Incorporation of fractional-order dynamics into an existing PI/PID DC motor control loop

The problem of changing the dynamics of an existing DC motor control system without the need of making internal changes is considered in the paper. In particular, this paper presents a method for incorporating fractional-order dynamics in an existing DC motor control system with internal PI or PID controller, through the addition of an external controller into the system and by tapping its original input and output signals. Experimental results based on the control of a real test plant from MATLAB/Simulink environment are presented, indicating the validity of the proposed approach.This work was partially supported by the following grants under the Slovak Grant Agency, the Slovak Research and Development Agency: VEGA 1/0552/14, VEGA 1/0729/12, VEGA 1/0497/11, VEGA 1/2578/12, and APVV-0482-11, and the European Union through the European Regional Development Fund, and the Estonian Doctoral School in Information and Communication Technology through the interdisciplinary project FOMCON

Conceptual Design of a Selectable Fractional-Order Differentiator for Industrial Applications

In the past decade, researchers working on fractional-order systems modeling and control have been considering working on the design and development of analog and digital fractional-order differentiators, i.e. circuits that can perform non-integer-order differentiation. It has been one of the major research areas under such field due to proven advantages over its integer-order counterparts. In particular, traditional integer-order proportional-integral-derivative (PID) controllers seem to be outperformed by fractional-order PID (FOPID or PIlambdaDmu) controllers. Many researches have emerged presenting the possibility of designing analog and digital fractional-order differentiators, but only restricted to a fixed order. In this paper, we present the conceptual design of a variable fractional-order differentiator in which the order can be selected from 0 to 1 with an increment of 0.05. The analog conceptual design utilizes operational amplifiers and resistor-capacitor ladders as main components, while a generic microcontroller is introduced for switching purposes. Simulation results through Matlab and LTSpiceIV show that the designed resistor-capacitor ladders can perform as analog fractional-order differentiation.This work was in part supported by grants VEGA 1/0552/14, 1/0729/12, 1/2578/12, 1/0497/11, and APVV-0482-11 from the Slovak Grant Agency, and the Slovak Research and Development Agency, respectively

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Introduction to the fractional control

[ES] Este trabajo pretende ser una introducción y una invitación al Control Fraccionario, entendido éste como el conjunto de aplicaciones del Cálculo Fraccionario en Teoría de Control. Quiere servir para que los miembros de la comunidad de control perciban cómo el cálculo fraccionario puede ampliar los horizontes de su disciplina. Por ello, el trabajo se ha estructurado como un libro de texto que recorre desde los fundamentos y definiciones básicas del cálculo fraccionario hasta las estrategias de implantación de controladores y filtros fraccionarios, pasando por el análisis de sistemas y el diseño de controladores. Finalmente, se hace un breve esbozo de la actualidad del control fraccionario.[EN] This work aims to introduce the reader to the essentials of Fractional Order Control (FOC), on the understanding that it refers to the set of applications of Fractional Calculus in Control Theory. At the same time, it aims to motivate the control community members to consider fractional calculus as a way to expand their discipline horizons. Consequently, the contents of this work have been organized following a book structure that covers from the fundamentals and basic definitions of fractional calculus, to the strategies for the implementation of fractional controllers and filters, going through the analysis and design of this type of systems and controllers. Finally, a short review of the state of the art of fractional order control is outlined.Vinagre, BM.; Monje, CA. (2010). Introducción al Control Fraccionario. Revista Iberoamericana de Automática e Informática industrial. 3(3):5-23. http://hdl.handle.net/10251/146267OJS5233

Introducción al Control Fraccionario

Este trabajo pretende ser una introducción y una invitación al Control Fraccionario, entendido éste como el conjunto de aplicaciones del Cálculo Fraccionario en Teoría de Control. Quiere servir para que los miembros de la comunidad de control perciban cómo el cálculo fraccionario puede ampliar los horizontes de su disciplina. Por ello, el trabajo se ha estructurado como un libro de texto que recorre desde los fundamentos y definiciones básicas del cálculo fraccionario hasta las estrategias de implantación de controladores y filtros fraccionarios, pasando por el análisis de sistemas y el diseño de controladores. Finalmente, se hace un breve esbozo de la actualidad del control fraccionario

Un primer acercamiento a una propuesta de un enlace robótico suave que actúa como un cuello.

Comunicación presentada a las XXXIX Jornadas de Automática, celebradas en Badajoz del 5 al 7 de Septiembre de 2018 y organizada por la Universidad de Extremadura.The purpose of this paper is to design a soft robotic neck prototype with two Degrees of Freedom (DOF) and propose a control system based on a fractional order PD controller (FPD). The neck will be able to perform movements of flexion, extension and lateral bending. To achieve these movements, the design is made based on a cable-driven mechanism, with components easy to manufacture in a 3D printer. Simulations are performed to validate the feasibility of the developed parallel robot prototype and the robustness of the proposed control scheme to mass changes at the tip.El propósito de este trabajo es diseñar un prototipo robótico de cuello suave con dos grados de libertad (DOF) y proponer un sistema de control basado en un controlador de PD de orden fraccional (FPD). El cuello podrá realizar movimientos de flexión, extensión y flexión lateral. Para lograr estos movimientos, el diseño se basa en un mecanismo accionado por cable, con componentes fáciles de fabricar en una impresora 3D. Se realizan simulaciones para validar la viabilidad del prototipo de robot paralelo desarrollado y la robustez del esquema de control propuesto para los cambios de masa en la punta.The Spanish Ministry of Economy and Competitiveness. HUMASOFT project, with reference DPI2016-75330-PpeerReviewe

Un primer acercamiento a una propuesta de un enlace robótico suave que actúa como un cuello.

Comunicación presentada a las XXXIX Jornadas de Automática, celebradas en Badajoz del 5 al 7 de Septiembre de 2018 y organizada por la Universidad de Extremadura.The purpose of this paper is to design a soft robotic neck prototype with two Degrees of Freedom (DOF) and propose a control system based on a fractional order PD controller (FPD). The neck will be able to perform movements of flexion, extension and lateral bending. To achieve these movements, the design is made based on a cable-driven mechanism, with components easy to manufacture in a 3D printer. Simulations are performed to validate the feasibility of the developed parallel robot prototype and the robustness of the proposed control scheme to mass changes at the tip.El propósito de este trabajo es diseñar un prototipo robótico de cuello suave con dos grados de libertad (DOF) y proponer un sistema de control basado en un controlador de PD de orden fraccional (FPD). El cuello podrá realizar movimientos de flexión, extensión y flexión lateral. Para lograr estos movimientos, el diseño se basa en un mecanismo accionado por cable, con componentes fáciles de fabricar en una impresora 3D. Se realizan simulaciones para validar la viabilidad del prototipo de robot paralelo desarrollado y la robustez del esquema de control propuesto para los cambios de masa en la punta.The Spanish Ministry of Economy and Competitiveness. HUMASOFT project, with reference DPI2016-75330-PpeerReviewe

Modeling of a soft robotic neck using machine learning techniques

[ES] En este trabajo se aborda el problema del modelado de un cuello robótico blando mediante el uso de diferentes arquitecturas de redes neuronales, estudiando la influencia en los resultados del número de capas de cada red y de su correspondiente función de activación. Se emplearan las funciones de activación Tangente Hiperbólica (TANH) y Unidad Lineal Exponencial (ELU). Los modelos obtenidos se compararan con un modelo basado en Perceptron Multicapa (MLP) de parámetros optimizados, así comocon el modelo cinemático analítico del cuello. Los resultados experimentales obtenidos demostraran la ventaja del empleo de las técnicas de aprendizaje automático para el modelado de sistemas altamente no lineales como el del cuello robótico blando, cuya característica elástica dificulta la formulación de un modelo analítico robusto.[EN] In this paper we address the problem of modeling a soft robotic neck by using different neural network architectures, studying the influence on the results of the number of layers of each network and its corresponding activation function. The Tangent Hyperbolic Tangent (TANH) and Exponential Linear Unit (ELU) activation functions are used. The obtained models are compared with a Multi-Layer Perceptron (MLP) with optimized parameters, as well as with the kinematic model of the neck. The experimental results demonstrate the advantage of using machine learning techniques for modeling highly nonlinear systems such as this soft robotic neck, whose elastic characteristics make it difficult to formulate a robust analytical model. Esta investigación ha recibido financiación del proyecto SOFIA: Articulación blanda inteligente con capacidades de re-configuración y modularidad para plataformas robóticas, con referencia PID2020-13194GB-I00, financiado por el Ministerio de Economía, Industria y Competitividad.Continelli, NA.; Nagua Cuenca, LF.; Monje, CA.; Balaguer, C. (2023). Modelado de un cuello robótico blando mediante aprendizaje automático. Revista Iberoamericana de Automática e Informática industrial. 20(3):282-292. https://doi.org/10.4995/riai.2023.1875228229220