P. Albertos

Universitat Politècnica de València | UPV · Department of Systems Engineering and Control

In this article, the event-triggered output regulation problem (EORP) under the denial-of-service (DoS) attacks is considered for networked switched systems (NSSs) with unstable switching dynamics (USDs). The USDs here refer to the unsolvable output regulation of each subsystem and the destabilization at partial switching instants, which indicates...

Durante las últimas décadas, los reguladores lineales basados en observadores de perturbaciones han experimentado un interés creciente entre la comunidad científica, principalmente, debido a sus buenas propiedades para tolerar cambios o incertidumbres en los sistemas. En este tutorial se aborda una revisión de dichos reguladores, analizando sus ele...

This paper is concerned with the event-triggered output regulation problem for a class of linear networked switched systems (NSSs). A mode-dependent alternate event-triggered mechanism (AETM) is integrated into the NSSs with transmission delays and packet losses for the first time based on continuous detection and periodic sampling, and a joint-des...

Good slow disturbances attenuation in a mold level control with stopper rod is very important for avoiding several product defects and keeping down casting interruptions. The aim of this work is to improve the accuracy of the diagnosis and compensation of an adaptive mold level control method for slow disturbances related to changes of stopper rod....

p class="p1">En este tutorial se resumen las principales características de una nueva metodología de diseño de sistemas de control para el seguimiento de trayectorias en procesos no lineales. Esta metodología, denominada LAB (Linear Algebra Based), fue presentada por los autores hace más de diez años y ha tenido una fuerte repercusión por su sencil...

Resumen En este tutorial se resumen las principales características de una nueva metodología de diseño de sistemas de control para el seguimiento de trayectorias en procesos no lineales. Esta metodología, denominada LAB (Linear Algebra Based), fue presentada por los autores hace mas de diez años y ha tenido una fuerte repercusión por su sencillez y...

Controlled plant stability always depends on some plant and controller parameters. If the dependency is not monotone, the system is denoted as conditionally stable. In this paper some basic parameters, such as the gain or the time delay, are considered to determine the linear time invariant plant stability by using frequency domain criteria. Also,...

In this chapter, the use of the Linear Algebra-Based Control Design (LAB CD) methodology is illustrated, being applied to a mobile robot. Initially, the simplest kinematic continuous time (CT) model of the robot is used and neither uncertainties nor external disturbances are considered. The simplicity of the proposed control structure is based on t...

In this chapter, the problem of uncertainty in the model is considered. Some ideas were already presented in the previous chapters, but here both the marine vessel treated in Chap. 5 and the batch reactor considered in the previous chapter are analyzed in detail. These two processes may be considered as representative of a broad class of processes...

In this chapter, the application of the methodology is extended to marine and aerial vehicles. Here, three representative systems are considered to show that the Linear Algebra-Based Control Design (LAB CD) methodology can be applied to systems of different nature. First, a model of a marine vessel is considered. It is interesting to note that the...

To control the same process in discrete time, this control design methodology is applied in this chapter. Several models and discretization approaches for the same process are considered. The simpler the model is, the easier the controller results, and its tuning also becomes easier. The advantages and drawbacks of designing the control by using mo...

In this chapter, the main features of the newly proposed control design methodology are presented. First, the class of systems to be considered is defined, and the key points in the design approach are drafted. Then, an introductory example allows the understanding of the main properties and to state the procedure to design the control. The Linear...

In this chapter, chemical industrial processes are considered, and Linear Algebra-Based Control Design (LAB CD) is the approach used to design the controller. First, the case of dealing with a nonlinear first principles–based model of the process is considered. Then, an experimental linearized model around an operating point is considered, and, aga...

In this introductory chapter, the main problem dealt with in the book is outlined, shortly reviewing the different control structures to implement the tracking of a given reference or profile. These structures appear to be complementary, and they should be combined in the search for an optimal solution of the problem. Most of the control design met...

In this chapter, the advantages of using this methodology to design the tracking control for nonlinear processes is first summarized, and later on, some issues and critical drawbacks are discussed. As always in discrete time (DT) control, sampling period selection is crucial and should be decided as a trade-off between computational load and contro...

Describes the use of linear algebra based control algorithms (LABC) emphasizing their ease to use in various domains Synthesizes and generalizes the LABC, delivering realistic applications examples with additive uncertainty and time delay Presents an alternative perspective of control systems theories This book summarizes the application of linear...

This book summarizes the application of linear algebra-based controllers (LABC) for trajectory tracking for practitioners and students across a range of engineering disciplines. It clarifies the necessary steps to apply this straight-forward technique to a non-linear multivariable system, dealing with continuous or discrete time models, and outline...

In this work, a controller design technique called linear algebra based controller (LABC) is presented. The controller is obtained following a systematic procedure that is summarized in this work. In addition, the influence of additive uncertainty on the tracking error is analyzed, and a solution using integrators is proposed. A mobile robot is use...

This paper presents a multirobot cooperative event based localization scheme with improved bandwidth usage in a heterogeneous group of mobile robots. The proposed method relies on an agent based framework that defines the communications between robots and on an event based Extended Kalman Filter that performs the cooperative sensor fusion from loca...

This papers deals with the problem of robust stabilization of a class of discrete systems with time-varying input delay and model uncertainties, where the state is assumed not to be fully accessible. Thus, a predictor-observer based controller is proposed. Furthermore, a control synthesis algorithm based on the Cone Complementarity Linearization (C...

This paper deals with asymptotic stabilization of a class of nonlinear input-delayed systems via dynamic output-feedback in the presence of disturbances. The proposed strategy has the structure of an observer-based control law, in which the observer estimates and predicts both the plant state and the external disturbance. A nominal delay value is a...

The problem of output stabilization and disturbance rejection for input-delayed systems is tackled in this work. First, a suitable transformation is introduced to translate mismatched disturbances into an equivalent input disturbance. Then, an extended state observer is combined with a predictive observer structure to obtain a future estimation of...

This paper deals with the control of simple process models with state-delays. A pre-compensator is used to cancel the delay. Due to the cancellation of some terms, the process as well as its undelayed part should be stable. Although the approach is general, in order to simplify the notation, second order systems are considered to describe the proce...

The mould level control for steel continuous casting is an open research problem. In ACINOX-Las Tunas steelwork there are occasional problems with the amplitude of mould level variations and with the stability of the control system. The control quality should be better satisfied and a robust nonlinear PI controller with guaranteed robustness design...

This paper presents an enhanced Extended State Observer (ESO)-based control strategy to deal with the disturbance attenuation problem for a class of non integral-chain systems subject to non-linear mismatched uncertainties and external disturbances. The proposed control strategy does not assume the integral-chain form and it is formed by a state-fe...

To address the difficulty of controlling industrial processes with long time delay, a novel design of dead-time compensator (DTC) is introduced, which can be used to predict the undelayed output response of any process (no matter stable or unstable) such that the control design may be focused on the delay-free part of the process for performance op...

In this work, a generalization of the Smith Predictor (SP) is proposed to control linear time-invariant (LTI) time-delay single-input single-output (SISO) systems. Similarly to the SP, the combination of any stabilizing output-feedback controller for the delay-free system with the proposed predictor leads to a stabilizing controller for the delayed...

There are many processes with multiple time-delays. These may appear in the direct path or in some feedback path. In this paper, a pre-compensator is designed in order to convert a multiple time-delays process to one with a single time-delay in the forward path. On this simpler model, any well-established approach to design the control for input/ou...

This paper deals with the problem of stabilizing a class of input-delayed systems with (possibly) nonlinear uncertainties by using explicit delay compensation. It is well known that plain predictive schemes lack robustness with respect to uncertain model parameters. In this work, an uncertainty estimator is derived for input-delay systems and combi...

In this paper, the robust design of the Uncertainty and Disturbance Estimator is tackled for a class of nonlinear systems. This strategy combines state-feedback control with a reduced-order disturbance observer. The design procedure is derived in the state-space framework, in contrast to frequency-based design methodologies, which are already studi...

The feed heating furnace is an important devise in many petrochemical processes. Keeping under control the temperature of the feeding improves the performance and quality of the final product. Industrial furnaces usually have multiple burners and parallel tube-passes to handle the throughputs and reduce the furnace pipe pressure. In this paper, a d...

The design of decoupling controllers for multivariable systems with time delays is a complex issue, even more for non-square plants, and some approximations are usually required. In this study, based on the inverted decoupling structure, a model-based designed centralised controller is decomposed into two controllers: One is in the direct path and...

In this paper, a new predictor-based control strategy for LTI systems with input delay and unknown disturbances is proposed. The disturbing signal and its derivatives up to the -th order are estimated by means of an observer, and then used to construct a prediction of the disturbance. Such prediction allows defining a new predictive scheme that tak...

In this paper, a new robust control strategy based on a predictor and the uncertainty and disturbance estimator (UDE) is developed for a class of uncertain nonlinear systems with input/output delays. The closed-loop system is analyzed and sufficient stability conditions are derived based on Lyapunov analysis. The proposed strategy is applied to the...

In this paper, a quaternion-based attitude controller for quadrotors is developed. The proposal is made up of two interconnected controllers: an outer loop, which consists of a nonlinear quaternion-based controller, deals with the kinematic model; the inner loop is based on the Active Disturbance Rejection Control and deals with the dynamic model....

In this paper, a robust control strategy is proposed to control the attitude and the altitude of quadrotors, based on an uncertainty and disturbance estimator (UDE). It is shown that the proposed controller can be tuned very easily, achieving the desired performance only by selecting an appropriate reference model and tuning a single parameter to t...

In this study, the problem of controlling integrating and unstable systems with long time delay is analysed in the discrete-time domain for digital implementation. Based on a generalised predictor-based control structure, where the plant time delay can be taken out of the control loop for the nominal plant, an analytical controller design is propos...

Partitioned systems have emerged as a result of the increasing computer processing power and application complexity and the needs to achieve more secure systems. The use of cache memories into real-time systems has been consolidated in order to mitigate the gap between CPU speed and memory performance. This paper introduces an extended task model i...

Multicore systems are present in many sectors and arriving others, as real-time systems, traditionally reluctant to them due to the difficulty to estimate worst case execution time in multicore platforms. However, partitioned systems integrated by a partitioning kernel and a set of partitions with different levels of criticality is one of the emerg...

The aim of this paper is to determine the stabilizing PID parametric region for multivariable systems. Firstly, a general equivalent transfer function parameterization method is proposed to construct the multiloop equivalent process for multivariable systems. Then, based on the equivalent single loops, a model-based method is presented to derive th...

The problem of trajectory tracking control in mobile robots under uncertainties is addressed in this paper. Following the results of mobile robots trajectory tracking reported in (Scaglia et al., 2010), the problem of model errors is focused and the zero convergence of tracking errors under polynomial uncertainties is demonstrated. A simple scheme...

Disturbances and uncertainties make very difficult the control of Unmanned Aerial Vehicles (UAV). The problem is even worse, if delays are involved in the process. The uncertainty and disturbance estimator (UDE) is a technique based on the idea that the unknown dynamics and disturbances of a system can be accurately approximated by passing them thr...

The central aim of ADRC is to actively reject the disturbance in the absence of a detailed mathematical model of the plant or the disturbance itself. For that purpose, the controller is designed based on the ideal, disturbance free, process where any discrepancies between the actual process and the ideal one are considered as disturbances, being es...

The evolution of the definition of industry into the Smart factories has provide a big improvements in terms of production efficiency and promoted new ways to implement interfaces between humans and machines. A factory plan, which is achieved by means of a set of missions, implies a set of control missions. In this work is introduced how to achieve...

In Networked Control Systems, time-varying delays and loss of data are two important problems to be taken into account. In this paper, in order to face them, the design of a predictor-observer for possible unstable systems is proposed. A delay-dependent time varying stability condition is expressed in terms of LMIs. Stability and robustness is prov...

Other than the simple discretization of continuous time controllers, digital controllers present specific characteristics allowing them to work in different operating conditions offering additional alternatives. The integration of control design and computer control implementation is crucial to achieve the best control performance: to consider the...

This paper deals with the problem of disturbance rejection in process control. The disturbances could be external or generated by model uncertainties. Different types of disturbances are considered and also different approaches are outlined to reject or reduce their effects. After a general introduction about the relevance of the disturbances in pr...

The flywheel inverted pendulum is an underactuated mechanical system with a nonlinear model but admitting a linear approximation around the unstable equilibrium point in the upper position. Although underactuated systems usually require nonlinear controllers, the easy tuning and understanding of linear controllers make them more attractive for desi...

Automatic control, as well as the introduction to programming, are subjects increasingly being taught to young engineering students. For this reason the availability of a suitable platform for the laboratory work becomes a critical decision, in order to promote students' motivation to experience the theoretical concepts studied in the classroom. Un...

This paper presents a local sensor fusion technique with an event-based global position correction to improve the localization of a mobile robot with limited computational resources. The proposed algorithms use a modified Kalman filter and a new local dynamic model of an Ackermann steering mobile robot. It has a similar performance but faster execu...

In this paper several algorithms to estimate the attitude of a UAS using low-cost sensors are reviewed and a new one including the angular velocity is proposed. The fusion of measurement coming from gyroscopes and accelerometers is based on the Kalman filter. A quadrotor experimental platform is used to compare the measurement systems. The estimati...

In this paper, an LMI based analysis approach to check the stability of closed-loop discrete-time linear systems with both time-varying state and measurement delays is pre-sented. The internal as well as the measurement delays are assumed to be time-varying but bounded. The stability analysis procedure allows to determine the delay intervals ensuri...

A new observer-predictor algorithm (OP-A) to estimate the roll and pitch angles in an aerial vehicle is proposed in this paper. The OP-A is based on a Kalman Filter (KF) and a discrete-time predictor. First, the KF estimates the desired states. It is well-known that an inherent delay is introduced during its computation. The predictor improves thes...

In this paper, a real-time state feedback Model Reference Adaptive Control strategy is developed for stabilization of a 3DOF Hover electromechanical system, and its disturbance rejection properties are analyzed.

This paper deals with the nonlinear control strategy to stabilize a rotating flywheel pendulum (RFP) at the unstable upper position. For that purpose a switched swing-up and stabilization control is proposed. A nonlinear model of the RFP is derived allowing for a computer simulation of its behavior in the full state space. Based on this model, a no...

The main goal of this monograph is to deal with both problems in an integral way: given a process to be controlled, how should a simple model be identified and used to design a controller to fulfill some requirements? This book is neither a comprehensive handbook of process control design [1] nor a treatise on system identification and parameter es...

This paper deals with the problem of controlling linear discrete-time tall multiple-input multiple-output plants, using a cascade philosophy approach. The main idea is to use a cascade architecture to regulate a subset of the plant outputs while keeping the rest of them bounded and, additionally, aiming at achieving a satisfactory disturbance compe...

This paper presents a sensor fusion framework that improves the localization of mobile robots with limited computational resources. It employs an event based Kalman Filter to combine the measurements of a global sensor and an inertial measurement unit (IMU) on an event based schedule, using fewer resources (execution time and bandwidth) but with si...

In this work, a general structure to control long time-delay plants is proposed and an easy methodology to tune the control parameters is outlined. All the sensitivity transfer functions are delay free. The proposed scheme is equivalent to the Smith predictor but able to cope with any kind of systems, including non-minimum phase, unstable and integ...

Underactuated systems are usually represented by nonlinear models and their control requires the design of nonlinear controllers. The flywheel inverted pendulum is a special case, also nonlinear, but admitting a linear approximation around the unstable equilibrium point in the upper position. In this paper, a linear controller is designed in two st...

A control system with distributed computing resources always should guarantee the safe control of the plant. In this contribution, the concept of control kernel is used for that purpose. Two types of nodes with different resources are defined: the powerful server node and the resource-constrained light node. This architecture allows to split the co...

In this article, robustness to model uncertainties are analysed in the context of discrete predictor-based state-feedback controllers for discrete-time input-delay systems with time-varying delay, in an LMI framework. The goal is comparing robustness of predictor-based strategies with respect to other (sub)optimal state feedback ones. A numerical e...

Developing embedded control systems requires to have the possibility of analyzing and evaluating new control algorithms before their implementation in the final system as well as their robust operation once implemented. For that purpose, a generic platform composed by the hypervisor XtratuM and RTOS PaRTiKLe is introduced in this paper. The interac...