Educational tool for the learning of thermal comfort control based on PMV-PPD indices

In this paper, an interactive educational tool designed for the learning of thermal comfort concepts is presented. Thermal comfort is one of the fundamental aspects of indoor environmental quality and energy savings in buildings. Comfort-based control and energy management constitute an important emergent sub-discipline of engineering studies. The developed tool allows for the definition of the thermal model of a house. Based on this model, thermal comfort is estimated through the predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) indices, and energy consumption is also calculated. The tool can communicate through Modbus TCP/IP protocol, providing external connectivity and data collection from the different sensors available in a building management system (BMS). In this way, it is possible to calculate in real-time the aforementioned comfort indices and propose corrective control indications to maintain the indoor-air conditions inside the optimal comfort range. A simple control strategy that can be applied to conventional HVAC systems is also addressed. The tool is available for degree students in control engineering. A survey was performed to evaluate the effectiveness of the proposed tool

Iterative Method for Tuning Multiloop PID Controllers Based on Single Loop Robustness Specifications in the Frequency Domain

Multiloop proportional-integral-derivative (PID) controllers are widely used for controlling multivariable processes due to their understandability, simplicity and other practical advantages. The main difficulty of the methodologies using this approach is the fact that the controllers of different loops interact each other. Thus, the knowledge of the controllers in the other loops is necessary for the evaluation of one loop. This work proposes an iterative design methodology of multiloop PID controllers for stable multivariable systems. The controllers in each step are tuned using single-input single-output (SISO) methods for the corresponding effective open loop process (EOP), which considers the interaction of the other loops closed with the controllers of the previous step. The methodology uses a frequency response matrix representation of the system to avoid process approximations in the case of elements with time delays or complicated EOPs. Consequently, different robustness margins on the frequency domain are proposed as specifications: phase margin, gain margin, phase and gain margin combination, sensitivity margin and linear margin. For each case, a PID tuning method is described and detailed for the iterative methodology. The proposals are exemplified with two simulations systems where the obtained performance is similar or better than that achieved by other authors

Development of an application for the study of distance measurement using UWB

[Resumen] Debido al desarrollo de la tecnología ultra-wideband en las últimas décadas dentro de los numerosos estándares de comunicación inalámbricos, en este trabajo se desarrolla una interfaz gráfica que permite realizar un análisis de esta tecnología en el campo de la medición de distancias y posicionamiento. Se utiliza para ello el módulo DWM1001-DEV, que incorpora dicha tecnología junto con diferentes modos de conexión y puertos de entrada y salida. La interfaz desarrollada permite establecer una conexión a través del puerto USB con el módulo mencionado y también de forma inalámbrica a través de una red Wi-Fi. Se plantea también el software de gestión de datos y su envío con una placa tipo Raspberry. Se muestra un conjunto de pruebas experimentales utilizando la interfaz y se realiza un estudio preliminar de la calidad de la medida de distancia entre dos módulos DWM1001-DEV.[Abstract] Due to the development of ultra-wideband technology in recent decades within the numerous wireless communication standards, this paper develops a graphical interface that allows an analysis of this technology in the field of distance measurement and positioning. For this purpose, the DWM1001-DEV module is used, which incorporates UWB technology together with different connection GPIO ports. The developed interface allows establishing a connection through the USB port with the mentioned module and also wirelessly through a Wi-Fi network. The data management software and its shipment with a Raspberry type board are also considered. A set of experimental tests using the interface is shown and a preliminary study of the quality of the distance measurement between two DWM1001-DEV modules is carried out.Universidad de Córdoba; IX Plan Propio GALILEO de Innovación y Transferenci

Interactive Tool for Frequency Domain Tuning of PID Controllers

This paper presents an interactive tool focused on the study of proportional-integral-derivative (PID) controllers. Nowadays, PID control loops are extensively used in industrial applications. However, it is reported that many of them are badly tuned. From an educational point of view, it is essential for undergraduate students in control engineering to understand the importance of tuning a control loop correctly. For this reason, the tool provides different PID tuning methods in the frequency domain for stable open-loop time-delay-free processes. The different designs can be compared interactively by the user, allowing them to understand concepts about stability, robustness, and performance in PID control loops. A survey and a comparative study were performed to evaluate the effectiveness of the proposed tool

A hybrid modeling approach for steady-state optimal operation of vapor compression refrigeration cycles

This paper presents a steady-state hybrid modeling approach for vapor compression refrigeration cycles which is intended to achieve an optimal system operation from an energy consumption point of view. The model development is based on a static characterization of the main components of the cycle using a hybrid approach, and their integration in a new optimization block. This block allows to determine completely the system stationary state by means of a non-linear optimization procedure subjected to several constraints such as mechanical limitations, component interactions, environmental conditions and cooling load demand. The proposed method has been tested in an experimental pilot plant with good results. Model validation for each identified hybrid model is carried out from a set of experimental data of 82 stationary operating points, with prediction errors below ±10%. The model is also globally validated by comparing experimental and simulated data, with a global mean relative absolute error less than 5%. The basic control structure consists of three decentralized control loops where the controller variables are the secondary fluid temperature at the evaporator inlet, the superheat, and the condenser pressure. While the secondary temperature is assumed as an imposed requirement, the optimal set-points of the other two control loops are searched offline using the proposed refrigerant cycle model. This set-point optimality is defined according to the coefficient of performance for minimizing the total electrical power consumption of the system at steady-state. This energy saving has been confirmed experimentally. The proposed method can be easily adapted for different sets of controlled variables in case of modification of the basic control structure. Furthermore, other energy efficiency metrics can be handily adopted. Considering the tradeoff between the accuracy and computational cost of the hybrid models, the proposed procedure is expected to be used in real-time applications

Adaptive Pitch Controller of a Large-Scale Wind Turbine Using Multi-Objective Optimization

This paper deals with the control problems of a wind turbine working in its nominal zone. In this region, the wind turbine speed is controlled by means of the pitch angle, which keeps the nominal power constant against wind fluctuations. The non-uniform profile of the wind causes tower displacements that must be reduced to improve the wind turbine lifetime. In this work, an adaptive control structure operating on the pitch angle variable is proposed for a nonlinear model of a wind turbine provided by FAST software. The proposed control structure is composed of a gain scheduling proportional–integral (PI) controller, an adaptive feedforward compensation for the wind speed, and an adaptive gain compensation for the tower damping. The tuning of the controller parameters is formulated as a Pareto optimization problem that minimizes the tower fore-aft displacements and the deviation of the generator speed using multi-objective genetic algorithms. Three multi-criteria decision making (MCDM) methods are compared, and a satisfactory solution is selected. The optimal solutions for power generation and for tower fore-aft displacement reduction are also obtained. The performance of these three proposed solutions is evaluated for a set of wind pattern conditions and compared with that achieved by a classical baseline PI controller

Educational software tool for decoupling control in wind turbines applied to a lab‐scale system

This paper presents an educational software tool, called wtControlGUI, whose main purpose is to show the applicability and performance of different decoupling control strategies in wind turbines. Nowadays wind turbines are a very important field in control engineering. Therefore, from an educational point of view, the tool also aims to improve the learning of multivariable control concepts applied on this control field. In addition, wtControlGUI allows for testing and control of a lab-scale system which emulates the dynamic response of a largescale wind turbine. The designed graphical user interface essentially allows simulation and experimental testing of decoupling networks and other multivariable methodologies, such as robust and decentralized control strategies. The tool is available for master degree students in control engineering. A survey was performed to evaluate the effectiveness of the proposed tool when used in educational related tasks

Laboratory of computational analysis in vibratory systems

Las vibraciones en sistemas mecánicos constituyen un problema clave en Ingeniería Mecánica por lo que resulta primordial su estudio en cualquier asignatura relacionada con Ingeniería Mecánica. Las ecuaciones que describen el movimiento de las vibraciones mecánicas son de sobra conocidas. Sin embargo, su solución puede ser muy compleja en función de las suposiciones del modelo empleado y las condiciones de contorno del sistema mecánico. La comprensión del significado físico de los parámetros involucrados en las ecuaciones y su influencia relativa es importante para los estudiantes. Se propone así el desarrollo de una interfaz gráfica bilingüe (español-inglés) para una mejor comprensión de los conceptos físicos y matemáticos implicados en teoría de vibraciones. Dicha herramienta serviría para la resolución de diferentes casos de estudio en función del nivel de complejidad requerido y se podría utilizar como laboratorio virtual de cara al análisis de la influencia de las distintas variables y parámetros implicados en el movimiento. Así, se potencia el enfoque autónomo del aprendizaje y por tanto se promueven el desarrollo de habilidades personales por parte del alumnado. La herramienta fue compilada en MatLab© y se ha utilizado por primera vez en la Universidad de Córdoba en el curso académico 2017-2018.Vibrations in mechanical systems is a key topic in mechanical engineering and its proper understanding is paramount for students of any course related to Mechanical Engineering. The equations of movement describing mechanical vibrations are well-known. The solutions of these equations can be very complex in terms of the assumptions of the models and the boundary conditions to which they are subjected. The understanding of the physical meaning of the parameters involved in the equations and their relative influence is important for students. This paper presents the development of a bilingual graphical interface (Spanish-English) for a better understanding of the physical and mathematical concepts related to discrete vibrations with multiple degrees of freedom in mechanical systems. The tool here developed constitutes a virtual lab for the analysis of the variables and parameters involved in the equations of movement in a step-by-step way, allowing to easily change the input parameter values so as to understand the importance of the different variables. Thus, the autonomous apprenticeship and the development of personal skills of students is enhanced and promoted. This lab was coded in MatLab© and is being used for the first time at the University of Cordoba during the academic year 2017-2018

Software Tool for Acausal Physical Modelling and Simulation

Modelling and simulation are key tools for analysis and design of systems and processes from almost any scientific or engineering discipline. Models of complex systems are typically built on acausal Differential-Algebraic Equations (DAE) and discrete events using Object-Oriented Modelling (OOM) languages, and some of their key concepts can be explained as symmetries. To obtain a computer executable version from the original model, several algorithms, based on bipartite symmetric graphs, must be applied for automatic equation generation, removing alias equations, computational causality assignment, equation sorting, discrete-event processing or index reduction. In this paper, an open source tool according to OOM paradigm and developed in MATLAB is introduced. It implements such algorithms adding an educational perspective about how they work, since the step by step results obtained after processing the model equations can be shown. The tool also allows to create models using its own OOM language and to simulate the final executable equation set. It was used by students in a modelling and simulation course of the Automatic Control and Industrial Electronics Engineering degree, showing a significant improvement in their understanding and learning of the abovementioned topics after their assessment