Design of state-feedback controllers for linear parameter varying systems subject to time-varying input saturation

All real-world systems are affected by the saturation phenomenon due to inherent physical limitations of actuators. These limitations should be taken into account in the controller’s design to prevent a possibly severe deterioration of the system’s performance, and may even lead to instability of the closed-loop system. Contrarily to most of the control strategies, which assume that the saturation limits are constant in time, this paper considers the problem of designing a state-feedback controller for a system affected by time-varying saturation limits with the objective to improve the performance. In order to tie variations of the saturation function to changes in the performance of the closed-loop system, the shifting paradigm is used, that is, some parameters scheduled by the time-varying saturations are introduced to schedule the performance criterion, which is considered to be the instantaneous guaranteed decay rate. The design conditions are obtained within the framework of linear parameter varying (LPV) systems using quadratic Lyapunov functions with constant Lyapunov matrices and they consist in a linear matrix inequality (LMI)-based feasibility problem, which can be solved efficiently using available solvers. Simulation results obtained using an illustrative example demonstrate the validity and the main characteristics of the proposed approach.Peer ReviewedPostprint (published version

Design of shifting output-feedback controllers for LPV systems subject to time-varying saturations

This paper considers the problem of designing a shifting output-feedback controller for polytopic linear parameter-varying (LPV) systems subject to time-varying saturations. By means of the LPV framework and the use of the Lyapunov theory, the shifting paradigm concept, and the ellipsoidal invariant theory, a linear matrix inequality (LMI)-based methodology for the controller's design is proposed. The resulting gain-scheduled controller holds the control action in the linearity region of the actuators and regulates online the closed-loop convergence taking into account the instantaneous saturation limit values. The proposed approach is validated by means of an illustrative example.This work has been partially funded by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project SaCoAV (ref. PID2020-114244RB-I00). This work has also been partially funded by AGAUR of Generalitat de Catalunya through the Advanced Control Systems (SAC) group grant (2017 SGR 482) and by the University of Stavanger through the project IN-12267. A. Ruiz is also supported by the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya, the European Social Fund (ESF) and AGAUR under a FI SDUR grant (ref. 2020 FI-SDUR 00097).Peer ReviewedPostprint (published version

Fault detection and isolation for autonomous mobile robot systems

This Project is about the fault detection and isolation with a tolerant control for autonomous mobile robot systems. The omnidirectional robot model is developed to obtain a benchmark that can be implemented as a simulator. The model obtained is non-linear, multivariable and unstable, thus the design of a controller is required. In order to make the system robust in front of faults we add an observer system to estimate the behavior of the plant and detect, if is possible, the system fault. Once detected the error system proceeds to isolate and perform a tolerant control to achieve the goals with virtual sensors and virtual actuator

Fault detection and isolation for autonomous mobile robot systems

This Project is about the fault detection and isolation with a tolerant control for autonomous mobile robot systems. The omnidirectional robot model is developed to obtain a benchmark that can be implemented as a simulator. The model obtained is non-linear, multivariable and unstable, thus the design of a controller is required. In order to make the system robust in front of faults we add an observer system to estimate the behavior of the plant and detect, if is possible, the system fault. Once detected the error system proceeds to isolate and perform a tolerant control to achieve the goals with virtual sensors and virtual actuator

Shifting H infinity linear parameter varying state-feedback controllers subject to time-varying input saturations

This paper establishes a methodology based on linear matrix inequalities (LMIs) to design a shifting H infinity linear parameter varying (LPV) state-feedback controller for systems affected by time-varying input saturations. By means of the shifting paradigm, the instantaneous saturation values are linked to a scheduling parameter vector. Then, the disturbance rejection is dealt with the quadratic boundedness concept and the shifting H infinity methodology. The design conditions are obtained within the LPV framework using ellipsoidal invariant sets, thus obtaining an LMI-based feasibility problem that can be solved via available solvers. Finally, the main characteristics of the proposed approach are validated by means of an illustrative example.This work has been partially funded by the Spanish State Re-search Agency (AEI) and the European Regional Development Fund(ERFD) through the project SCAV (ref. MINECO DPI2017-88403-R) and the SMART project (ref. nºEFA 153/16 Interreg Coop-eration Program POCTEFA 2014-2020). This work has also beenpartially funded by AGAUR of Generalitat de Catalunya throughthe Advanced Control Systems (SAC) group grant (2017 SGR 482)and by the Spanish State Research Agency through the Maria deMaeztu Seal of Excellence to IRI (MDM-2016-0656). A. Ruiz isalso supported by Formaci ́o Personal Investigador a la UniversitatPolit`ecnica de Catalunya under an FPI-UPC 2018 grant (ref. 20 FPI-UPC 2018). D. Rotondo has been also supported by AEI through theJuan de la Cierva - Formacion grant (FJCI-2016-29019) and by theUniversity of Stavanger through the project IN-12267Peer ReviewedPostprint (author's final draft

Design of state-feedback controllers for linear parameter varying systems subject to time-varying input saturation

All real-world systems are affected by the saturation phenomenon due to inherent physical limitations of actuators. These limitations should be taken into account in the controller’s design to prevent a possibly severe deterioration of the system’s performance, and may even lead to instability of the closed-loop system. Contrarily to most of the control strategies, which assume that the saturation limits are constant in time, this paper considers the problem of designing a state-feedback controller for a system affected by time-varying saturation limits with the objective to improve the performance. In order to tie variations of the saturation function to changes in the performance of the closed-loop system, the shifting paradigm is used, that is, some parameters scheduled by the time-varying saturations are introduced to schedule the performance criterion, which is considered to be the instantaneous guaranteed decay rate. The design conditions are obtained within the framework of linear parameter varying (LPV) systems using quadratic Lyapunov functions with constant Lyapunov matrices and they consist in a linear matrix inequality (LMI)-based feasibility problem, which can be solved efficiently using available solvers. Simulation results obtained using an illustrative example demonstrate the validity and the main characteristics of the proposed approach.Peer Reviewe