Adaptive inverse control of a vibrating coupled vessel-riser system with input backlash

This article involves the adaptive inverse control of a coupled vessel-riser system with input backlash and system uncertainties. By introducing an adaptive inverse dynamics of backlash, the backlash control input is divided into a mismatch error and an expected control command, and then a novel adaptive inverse control strategy is established to eliminate vibration, tackle backlash, and compensate for system uncertainties. The bounded stability of the controlled system is analyzed and demonstrated by exploiting the Lyapunov’s criterion. The simulation comparison experiments are finally presented to verify the feasibility and effectiveness of the control algorithm

Boundary control of parabolic PDE using adaptive dynamic programming

In this dissertation, novel adaptive/approximate dynamic programming (ADP) based state and output feedback control methods are presented for distributed parameter systems (DPS) which are expressed as uncertain parabolic partial differential equations (PDEs) in one and two dimensional domains. In the first step, the output feedback control design using an early lumping method is introduced after model reduction. Subsequently controllers were developed in four stages; Unlike current approaches in the literature, state and output feedback approaches were designed without utilizing model reduction for uncertain linear, coupled nonlinear and two-dimensional parabolic PDEs, respectively. In all of these techniques, the infinite horizon cost function was considered and controller design was obtained in a forward-in-time and online manner without solving the algebraic Riccati equation (ARE) or using value and policy iterations techniques. Providing the stability analysis in the original infinite dimensional domain was a major challenge. Using Lyapunov criterion, the ultimate boundedness (UB) result was demonstrated for the regulation of closed-loop system using all the techniques developed herein. Moreover, due to distributed and large scale nature of state space, pure state feedback control design for DPS has proven to be practically obsolete. Therefore, output feedback design using limited point sensors in the domain or at boundaries are introduced. In the final two papers, the developed state feedback ADP control method was extended to regulate multi-dimensional and more complicated nonlinear parabolic PDE dynamics --Abstract, page iv

MATLAB

This excellent book represents the final part of three-volumes regarding MATLAB-based applications in almost every branch of science. The book consists of 19 excellent, insightful articles and the readers will find the results very useful to their work. In particular, the book consists of three parts, the first one is devoted to mathematical methods in the applied sciences by using MATLAB, the second is devoted to MATLAB applications of general interest and the third one discusses MATLAB for educational purposes. This collection of high quality articles, refers to a large range of professional fields and can be used for science as well as for various educational purposes

Nonlinear robust H∞ control.

A new theory is proposed for the full-information finite and infinite horizontime robust H∞ control that is equivalently effective for the regulation and/or tracking problems of the general class of time-varying nonlinear systems under the presence of exogenous disturbance inputs. The theory employs the sequence of linear-quadratic and time-varying approximations, that were recently introduced in the optimal control framework, to transform the nonlinear H∞ control problem into a sequence of linearquadratic robust H∞ control problems by using well-known results from the existing Riccati-based theory of the maturing classical linear robust control. The proposed method, as in the optimal control case, requires solving an approximating sequence of Riccati equations (ASRE), to find linear time-varying feedback controllers for such disturbed nonlinear systems while employing classical methods. Under very mild conditions of local Lipschitz continuity, these iterative sequences of solutions are known to converge to the unique viscosity solution of the Hamilton-lacobi-Bellman partial differential equation of the original nonlinear optimal control problem in the weak form (Cimen, 2003); and should hold for the robust control problems herein. The theory is analytically illustrated by directly applying it to some sophisticated nonlinear dynamical models of practical real-world applications. Under a r -iteration sense, such a theory gives the control engineer and designer more transparent control requirements to be incorporated a priori to fine-tune between robustness and optimality needs. It is believed, however, that the automatic state-regulation robust ASRE feedback control systems and techniques provided in this thesis yield very effective control actions in theory, in view of its computational simplicity and its validation by means of classical numerical techniques, and can straightforwardly be implemented in practice as the feedback controller is constrained to be linear with respect to its inputs

Control of Continuous Casting Process Based on Two-Dimensional Flow Field Measurements

Two-dimensional flow field measurement allows us to obtain detailed information about the processes inside the continuous casting mould. This is very important because the flow phenomena in the mould are complex, and they significantly affect the steel quality. For this reason, control based on two-dimensional flow monitoring has a great potential to achieve substantial improvement over the conventional continuous casting control. Two-dimensional flow field measurement provides large amounts of measurement data distributed within the whole cross-section of the mould. An experimental setup of the continuous casting process called Mini-LIMMCAST located in Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, is used for this thesis. This thesis examines two alternatives of flow measurement sensors: Ultrasound Doppler Velocimetry (UDV) and Contactless Inductive Flow Tomography (CIFT). Both sensor variants can obtain information on the velocity profile in the mould. Two approaches were considered to create the process model needed for model-based control: a spatially discretized version of a model based on partial differential equations and computational fluid dynamics and a model obtained using system identification methods. In the end, system identification proved to be more fruitful for the aim of creating the model-based controller. Specific features of the flow were parametrized to obtain the needed controlled variables and outputs of identified models. These features are mainly related to the exiting jet angle and the meniscus velocity. The manipulated variables considered are electromagnetic brake current and stopper rod position. Model predictive control in several versions was used as the main control approach, and the results of simulation experiments demonstrate that the model predictive controller can control the flow and achieve the optimum flow structures in the mould using UDV. CIFT measurements can provide similar velocity profiles. However, further technical developments in the CIFT sensor signal processing, such as compensating for the effects of the strong and time-varying magnetic field of the electromagnetic brake on CIFT measurements, are necessary if this sensor is to be used for closed-loop control.Two-dimensional flow field measurement allows us to obtain detailed information about the processes inside the continuous casting mould. This is very important because the flow phenomena in the mould are complex, and they significantly affect the steel quality. For this reason, control based on two-dimensional flow monitoring has a great potential to achieve substantial improvement over the conventional continuous casting control. Two-dimensional flow field measurement provides large amounts of measurement data distributed within the whole cross-section of the mould. An experimental setup of the continuous casting process called Mini-LIMMCAST located in Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, is used for this thesis. This thesis examines two alternatives of flow measurement sensors: Ultrasound Doppler Velocimetry (UDV) and Contactless Inductive Flow Tomography (CIFT). Both sensor variants can obtain information on the velocity profile in the mould. Two approaches were considered to create the process model needed for model-based control: a spatially discretized version of a model based on partial differential equations and computational fluid dynamics and a model obtained using system identification methods. In the end, system identification proved to be more fruitful for the aim of creating the model-based controller. Specific features of the flow were parametrized to obtain the needed controlled variables and outputs of identified models. These features are mainly related to the exiting jet angle and the meniscus velocity. The manipulated variables considered are electromagnetic brake current and stopper rod position. Model predictive control in several versions was used as the main control approach, and the results of simulation experiments demonstrate that the model predictive controller can control the flow and achieve the optimum flow structures in the mould using UDV. CIFT measurements can provide similar velocity profiles. However, further technical developments in the CIFT sensor signal processing, such as compensating for the effects of the strong and time-varying magnetic field of the electromagnetic brake on CIFT measurements, are necessary if this sensor is to be used for closed-loop control.

International Conference on Mathematical Analysis and Applications in Science and Engineering – Book of Extended Abstracts

The present volume on Mathematical Analysis and Applications in Science and Engineering - Book of Extended Abstracts of the ICMASC’2022 collects the extended abstracts of the talks presented at the International Conference on Mathematical Analysis and Applications in Science and Engineering – ICMA2SC'22 that took place at the beautiful city of Porto, Portugal, in June 27th-June 29th 2022 (3 days). Its aim was to bring together researchers in every discipline of applied mathematics, science, engineering, industry, and technology, to discuss the development of new mathematical models, theories, and applications that contribute to the advancement of scientific knowledge and practice. Authors proposed research in topics including partial and ordinary differential equations, integer and fractional order equations, linear algebra, numerical analysis, operations research, discrete mathematics, optimization, control, probability, computational mathematics, amongst others. The conference was designed to maximize the involvement of all participants and will present the state-of- the-art research and the latest achievements.info:eu-repo/semantics/publishedVersio