Papers by Felipe Espinosa
A simplified event-triggering condition non-dependent on measurement error
This paper presents a simplified triggering mechanism for event-triggered control systems. The no... more This paper presents a simplified triggering mechanism for event-triggered control systems. The novelty of our work resides in the use of a triggering condition that only updates the controller when the time derivative of the Lyapunov function becomes non-negative, without taking into account the measurement error. Directly or indirectly, most previous works use the measurement error in the triggering condition, usually defining this error as the difference between the states of the plant under continuous and aperiodic implementation. The main idea of our proposal is to force the system to maintain the last control update whenever it is approaching the equilibrium point. To demonstrate the advantages of our triggering condition, we compare it with other control alternatives using the double integrator problem as a case study.
Analysis of the optimal sampling rate for state estimation in sensor networks with delays
Isa Transactions, May 1, 2017
When addressing the problem of state estimation in sensor networks, the effects of communications... more When addressing the problem of state estimation in sensor networks, the effects of communications on estimator performance are often neglected. High accuracy requires a high sampling rate, but this leads to higher channel load and longer delays, which in turn worsens estimation performance. This paper studies the problem of determining the optimal sampling rate for state estimation in sensor networks from a theoretical perspective that takes into account traffic generation, a model of network behaviour and the effect of delays. Some theoretical results about Riccati and Lyapunov equations applied to sampled systems are derived, and a solution was obtained for the ideal case of perfect sensor information. This result is also interesting for non-ideal sensors, as in some cases it works as an upper bound of the optimisation solution.
One of the main challenges in wireless cyber-physical systems is to reduce the load of the commun... more One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.
Modelado de un motor DC. Diseño, simulación y construcción del sistema de control de velocidad
El trabajo presentado refleja la estructura de una practica de la asignatura laboratorios de sist... more El trabajo presentado refleja la estructura de una practica de la asignatura laboratorios de sistemas electronicos de control discreto. La practica se ha planificado para que integre diferentes aspectos considerados basicos en la formacion de un disenador de sistemas de control: a)manejo de herramientas software que faciliten el diseno y simulacion de controladores, b)construccion de la arquitectura hardware que permite aplicar directamente a un proceso real de algoritmos de control validados mediante simulacion. El objetivo del sistema es el control en lazo cerrado de la velocidad angular de un motor de continua con encorder optico.
A simplified event-triggering condition non-dependent on measurement error
2017 3rd International Conference on Event-Based Control, Communication and Signal Processing (EBCCSP), 2017
This paper presents a simplified triggering mechanism for event-triggered control systems. The no... more This paper presents a simplified triggering mechanism for event-triggered control systems. The novelty of our work resides in the use of a triggering condition that only updates the controller when the time derivative of the Lyapunov function becomes non-negative, without taking into account the measurement error. Directly or indirectly, most previous works use the measurement error in the triggering condition, usually defining this error as the difference between the states of the plant under continuous and aperiodic implementation. The main idea of our proposal is to force the system to maintain the last control update whenever it is approaching the equilibrium point. To demonstrate the advantages of our triggering condition, we compare it with other control alternatives using the double integrator problem as a case study.
Revista Iberoamericana de Automática e Informática industrial, 2020
Un vehículo de guiado automático (Automatic Guided Vehicle –AGV-en inglés) es un sistema de trans... more Un vehículo de guiado automático (Automatic Guided Vehicle –AGV-en inglés) es un sistema de transporte industrial completamente automatizado y alimentado por baterías. Estos vehículos son ampliamente utilizados en el sector industrial para sustituir a carretillas manuales y cintas transportadoras. El reto de la utilización de AGVs como agentes de transporte en entornos industriales pasa por dotarles de la inteligencia suficiente para desarrollar tareas colaborativas. Dentro de estas tareas colaborativas se diferencia el transporte multi-AGV de un objeto del transporte multi-AGV de múltiples objetos. Este trabajo presenta el estado del arte de las soluciones de transporte cooperativo de un objeto entre varios AGVs. Para ello, se revisan los fundamentos teóricos y se clasifican y describen varias propuestas para su resolución. Finalmente se propone una solución de control remoto centralizado para el transporte de una carga con AGVs omnidireccionales.
Lyapunov Self-triggered Controller for Nonlinear Trajectory Tracking of Unicycle-type Robot
International Journal of Control, Automation and Systems, 2020
This paper focuses on the design and implementation of an aperiodic control of nonholonomic robot... more This paper focuses on the design and implementation of an aperiodic control of nonholonomic robots tracking nonlinear trajectories. The main objective of our controller is to reduce the number of updates while preserving control performance guarantees. To solve the problem in a more efficient way, we design two aperiodic control solutions, one to reach a target point and a second to track a predefined nonlinear trajectory. Unlike most previous work, our triggering condition only updates the controller when the time derivative of the Lyapunov function becomes non-negative, without taking into account the measurement error. Multiple simulated results with different initial conditions are included, showing how our control solution significantly reduces the need for communication in comparison with periodic and other aperiodic strategies while preserving a desired tracking performance. To validate the proposal experimental tests of each control technique with a P3-DX robot remotely controlled through an IEEE 802.11g wireless network are also carried out.
International Journal of Intelligent Machines and Robotics, 2018
This paper addresses the design and presents the experimental results of an aperiodic remote-cont... more This paper addresses the design and presents the experimental results of an aperiodic remote-controlled mechatronic plant using a MiniDK2 electronic development board. We compare the classic periodic control solution with our self-triggered approach. The triggering mechanism consists of evaluating if the measurement error exceeds a predefined value. This measurement error is defined as the difference between the output signal of a model with and without a sample-and-hold that is activated only at the triggering instants. The minimum inter-execution time is the reference period and the maximum time is set by the designer, guaranteeing the stability of the closed loop system. At each new triggering instant, the remote controller receives a new measurement of the system and sends the actuation signal to the mechatronic plant.
A New Strategy of Non-Linear Trajectory Generation for a Platoon to Reduce Inter-Vehicle Error Distance Estimation
IFAC Proceedings Volumes, 2004
Abstract This work is focused on estimating the distance error between vehicles of a platoon. Thi... more Abstract This work is focused on estimating the distance error between vehicles of a platoon. This error is especially serious in non-linear trajectories and it gives place to lateral and longitudinal oscillations in the platoon guidance. For this reason, a new strategy is presented in which the leader, divides the trajectory into sub-trajectories as a function of the curvature and generates a set of points separated by a sampling-distance which is calculated as a function of the curvature in order to limit the inter-vehicle spacing error. This set of points is considered as the reference trajectory, which all the other vehicles have to follow.
Analysis of the optimal sampling rate for state estimation in sensor networks with delays
ISA Transactions, 2017
When addressing the problem of state estimation in sensor networks, the effects of communications... more When addressing the problem of state estimation in sensor networks, the effects of communications on estimator performance are often neglected. High accuracy requires a high sampling rate, but this leads to higher channel load and longer delays, which in turn worsens estimation performance. This paper studies the problem of determining the optimal sampling rate for state estimation in sensor networks from a theoretical perspective that takes into account traffic generation, a model of network behaviour and the effect of delays. Some theoretical results about Riccati and Lyapunov equations applied to sampled systems are derived, and a solution was obtained for the ideal case of perfect sensor information. This result is also interesting for non-ideal sensors, as in some cases it works as an upper bound of the optimisation solution.
IEEE Transactions on Education, 2016
Continual advances in information and communication technologies (ICT) are revolutionizing virtua... more Continual advances in information and communication technologies (ICT) are revolutionizing virtual education, and bringing new tools on the market that provide virtual solutions to a range of problems. Nevertheless, non-virtual experimentation using Computer-Aided Control System Design tools is still fundamental for future engineers. This paper describes a control course lab element, designed to teach electronic control engineering, in which students use a networked control system to steer and drive an electric car prototype. Multidisciplinary in nature, this lab allows students to take advantage of their previous academic training as they model the plant from an open-loop test, and contrast the simulated behavior with experimental results obtained on the prototype. A goal in this work was that students, across multiple engineering disciplines, should be able integrate the knowledge acquired throughout their degree studies. An evaluation of students' grades, and their perception of the course, was conducted; this confirmed the educational benefits of the approach.
Camera calibration parameters for oriented person re-identification
Proceedings of the 9th International Conference on Distributed Smart Cameras, 2015
Person re-identification is a challenging task when there exist strong appearance changes for dif... more Person re-identification is a challenging task when there exist strong appearance changes for different viewpoints of the person captured by a distributed camera network. To better solve this issue a multi-view oriented model of the person has been proposed. In this paper, we analyze the camera calibration parameters required to be used in the oriented people re-identification and propose a method to retrieve those values to be used in the capture of people perspectives with different known orientations respect to the camera. Usually, individual camera calibration parameters on a large distributed camera network are not available. A self-calibration method through the usage of short-term trackers of multiple persons is proposed. Only two extrinsic camera calibration parameters are required. Experimental results based on the processing of different public datasets demonstrate the effectiveness of our approach.
Aperiodic Consensus Control for Tracking Nonlinear Trajectories of a Platoon of Vehicles
2015 IEEE 18th International Conference on Intelligent Transportation Systems, 2015
This article presents an aperiodic control solution for the remote guidance of a convoy of intell... more This article presents an aperiodic control solution for the remote guidance of a convoy of intelligent vehicles tracking nonlinear trajectories. To accomplish this, it is assumed that the longitudinal and lateral stability problems are decoupled. A centralized self-triggered consensus controller ensures convoy stability, thus maintaining the desired distance between vehicles while also achieving a significant reduction in the number of times the channel is accessed. In addition, a decentralized self-triggered controller is designed for each follower to track nonlinear trajectories. With this self-triggered approach, each vehicle monitors its own state only at precise instants. The main contribution of this proposal is to reduce the wireless channel load while preserving the tracking performance of the convoy.
Implementación sobre FPGA´s de un Sistema Odométrico para una Carretilla Industrial
En este trabajo se analiza el diseño e implementación de un sistema electrónico, en base a FPGAs,... more En este trabajo se analiza el diseño e implementación de un sistema electrónico, en base a FPGAs, que proporciona información de la posición y velocidad de una carretilla industrial. Estas se deducen a partir del cómputo de las revoluciones de los ejes de las ruedas, dotados de encoders a tal efecto. La tarjeta desarrollada permite el manejo de hasta cuatro ejes distintos, cuyos datos de velocidad y posición pueden ser leídos desde dos puertos completamente independientes.
A trajectory tracking controller with dynamic gains for mobile robots
2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2011
This paper presents a new fuzzy controller for trajectory tracking for unicycle-like mobile robot... more This paper presents a new fuzzy controller for trajectory tracking for unicycle-like mobile robots, represented by a Takagi-Sugeno fuzzy model. Such controller allows setting different gains for the controller, according to the values of the velocity of the trajectory and the values of the tracking error. The noise inherent to the robot odometry is treated by the fuzzy controller itself, not requiring the use of filters. The stability of the developed controller is proven based on the theory of Lyapunov. Experimental results are also presented, and show that the proposed controller is effectively able to guide the robot during a trajectory tracking task. I. INTRODUCTION The fuzzy control has emerged in the 70s as a heuristic method based on the designer's knowledge about the process to be controlled, achieving success after the publication of the works of Zadeh (1) and Mandani (2). This type of methodology has the advantage of controlling a plant without necessarily knowing its dynamics. Nevertheless, to prove the stability of these fuzzy controllers is a difficult task (3). In the field of mobile robotics, several works have used the heuristic methodology to design fuzzy controllers, without studying the stability of the system: (4) and (5) discuss obstacle avoidance, while (6)-(9) discuss trajectory tracking. Since 1985, due to the necessity of a formal proof of the stability of the control system, fuzzy controllers have gotten a new focus with the Takagi-Sugeno (TS) fuzzy controllers (10). Unlike the fuzzy controllers based on heuristics, the work of Tanaka and Sugeno (11) showed that TS fuzzy con- trollers can be designed rigorously, following methodologies that can be reproduced consistently, ensuring stability and several performance criteria in closed loop (12). According to (3) and (12), the technique most commonly adopted for the design of controllers represented in the TS fuzzy model is the Parallel Distributed Compensation (PDC) (13). This technique is interesting because allows using linear control techniques in nonlinear plants, through the representation of the nonlinear plant by a set of linear dynamic subsystems, locally valid, interpolated in a smooth, non-linear and convex form (12). The works reported in (14), (15) and (16) used a PDC technique to design controllers for trajectory tracking with mobile robots. The design procedure of the TS fuzzy controllers via the PDC technique consists in solving a problem of linear matrix inequalities (LMI). The solution to this problem is derived from the study of the stability of this kind of system, and allows designing a linear controller for each of the subsystems that model the nonlinear plant. Nevertheless, this technique limits the shape of the controller, which should have the same number of linear dynamic subsystems as the model of the plant, and although the PDC technique is based in fuzzy model, it is impossible to use the designer's knowledge about the process. In this article, through the feedback of robot orientation, it was possible to design a fuzzy TS model without using the PDC technique. More than this, it was possible to design the controller using the heuristic knowledge of the problem treated, which is the trajectory tracking with a unicycle-like mobile robot. The noise inherent in the robot system odom- etry is treated by the fuzzy controller itself, not requiring the use of filters. The stability of the developed controller is proved based on the theory of Lyapunov. Experimental results demonstrate that the developed controller is quite efficient, allowing the robot to follow the desired trajectory with small errors. The paper is hereinafter organized in the following sec- tions: Section 2, presenting the kinematic model of the controlled reference point that shall track the reference trajectory; Section 3, presenting the proposed controller and discussing the stability of the system; Section 4, presenting the experimental results, and finally, Section 5, presenting the conclusion of the work.
Navigation System for a Mobile Robot by Means of an Infrared System
Intelligent Components and Instruments for Control Applications 1994, 1994
Abstract This paper describes how an infrared system could improve a mobile robot following a pat... more Abstract This paper describes how an infrared system could improve a mobile robot following a path using an odometric system. The infrared system takes out the accumulative errors given by the odometrics, and the tracking errors are minimized using a Kaiman filter.
Fuzzy Decentralized Control for guidance of a convoy of robots in non-linear trajectories
2010 IEEE 15th Conference on Emerging Technologies & Factory Automation (ETFA 2010), 2010
... Carlos Santos, Felipe Espinosa, Daniel Pizarro, Fernando Valdés, Enrique Santiso, Isabel Díaz... more ... Carlos Santos, Felipe Espinosa, Daniel Pizarro, Fernando Valdés, Enrique Santiso, Isabel Díaz Electronics Department. ... Campus Universitario s/n. 28871 Alcalá de Henares (Spain) {carlos.santos,espinosa, pizarro, fernando.valdes, santiso, isabel ... [4] CF Hsu, WJ Wang, TT Lee ...
Application of advanced digital control techniques to the drive and trajectory tracking system of a wheelchair for the disabled
1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)
Presents the basis and results of the application of advanced digital control techniques to the d... more Presents the basis and results of the application of advanced digital control techniques to the drive and trajectory tracking systems of a wheelchair for the disabled. The adaptive optimal control of the differential drive of the vehicle contributes to improve the guidance system safety and reliability. Furthermore, the incorporation of an optimal controller in order to minimise the location error
Reduction of lateral and longitudinal oscillations of vehicle’s platooning by means of decentralized overlapping control
2007 46th IEEE Conference on Decision and Control, 2007
Page 1. AbstractIn this paper authors present a novel method for platoon formation and control i... more Page 1. AbstractIn this paper authors present a novel method for platoon formation and control in linear as well as non-linear trajectories. Tracking stability and string-stability are achieved through a decentralized overlapping ...
Communication architecture based on Player/Stage and sockets for cooperative guidance of robotic units
2008 16th Mediterranean Conference on Control and Automation, 2008
... 3] Felipe Espinosa , AbdelBaset MH ... 2006 [4] Espinosa, F., Awawdeh, AMH, Mazo, M. Jr., Rod... more ... 3] Felipe Espinosa , AbdelBaset MH ... 2006 [4] Espinosa, F., Awawdeh, AMH, Mazo, M. Jr., Rodrıguez, JM, Bo-cos, A. Manzano, M. Reduction of lateral and longitudinal oscillations of vehicles' platooning by means of decentralizad overlapping control ... 10] Yang, L., Wang, FY, 2007 ...
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Papers by Felipe Espinosa