Continuous Control Systems Research Articles

Modern air protection technologies at thermal power plants (review)

Realization of the ecologically safe technologies for fuel combustion in the steam boiler furnaces and the effective ways for treatment of flue gases at modern thermal power plants have been analyzed. The administrative and legal measures to stimulate introduction of the technologies for air protection at TPPs have been considered. It has been shown that both the primary intrafurnace measures for nitrogen oxide suppression and the secondary flue gas treatment methods are needed to meet the modern ecological standards. Examples of the environmentally safe methods for flame combustion of gas-oil and solid fuels in the boiler furnaces have been provided. The effective methods and units to treat flue gases from nitrogen and sulfur oxides and flue ash have been considered. It has been demonstrated that realization of the measures for air protection should be accompanied by introduction of the systems for continuous instrumentation control of the composition of combustion products in the gas path of boiler units and for monitoring of atmospheric emissions.

Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy

It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

Continuous, saturation, and discontinuous tokamak plasma vertical position control systems

This paper is devoted to the design and comparison of unstable plasma vertical position control systems in the T-15 tokamak with the application of two types of actuators: a multiphase thyristor rectifier and a transistor voltage inverter. An unstable dynamic element obtained by the identification of plasma-physical DINA code was used as the plasma model. The simplest static feedback state space control law was synthesized as a linear combination of signals accessible to physical measurements, namely the plasma vertical displacement, the current, and the voltage in a horizontal field coil, to solve the pole placement problem for a closed-loop system. Only one system distinctive parameter was used to optimize the performance of the feedback system, viz., a multiple real pole. A first-order inertial unit was used as the rectifier model in the feedback. A system with a complete rectifier model was investigated as well. A system with the voltage inverter model and static linear controller was brought into a sliding mode. As this takes place, real time delays were taken into account in the discontinuous voltage inverter model. The comparison of the linear and sliding mode systems showed that the linear system enjoyed an essentially wider range of the plant model parameters where the feedback system was stable.

Synthesis of reactive controllers for hybrid systems (keynote)

Decision-making logic in hybrid systems is responsible for selecting modes of operation for the underlying (continuous) control system, reacting to external events and failures in the system, and insuring that the overall control system is satisfying safety and performance specifications. Tools from computer science, such as model-checking and logic synthesis, combined with design patterns from feedback control theory provide new approaches to solving these problems. A major shift is the move from ``design then verify'' to ``specify then synthesize'' approaches to controller design that allow simultaneous synthesis of high-performance, robust control laws and correct-by-construction decision-making logic.

Optimal Preview Control for a Class of Linear Continuous Stochastic Control Systems in the Infinite Horizon

This paper discusses the optimal preview control problem for a class of linear continuous stochastic control systems in the infinite horizon, based on the augmented error system method. Firstly, an assistant system is designed and the state equation is translated to the assistant system. Then, an integrator is introduced to construct a stochastic augmented error system. As a result, the tracking problem is converted to a regulation problem. Secondly, the optimal regulator is solved based on dynamic programming principle for the stochastic system, and the optimal preview controller of the original system is obtained. Compared with the finite horizon, we simplify the performance index. We also study the stability of the stochastic augmented error system and design the observer for the original stochastic system. Finally, the simulation example shows the effectiveness of the conclusion in this paper.

Predictive control of nonlinear continuous networked control systems with large time-varying transmission delays and transmission protocols

In this paper, we consider a class of globally Lipschitz nonlinear continuous networked control systems (NCS) incorporating large time-varying transmission delays and transmission protocols of communication networks with periodic sampling. To stabilize the NCS, we propose a new predictive control design scheme with plant outputs as the only available data. With uniformly globally exponentially stable (UGES) protocols, input-to-state stability of the entire NCS is ensured by small gain theory. In particular, the predictive controller can compensate transmission delays with any finite upper bound under the constraint that the sampling periods of the plant output and the observer output are small enough as well as the constraint that the predictor is accurate enough. The scheme is applied to a benchmark example to illustrate the effectiveness of our proposed method.

Dynamic building energy performance analysis: A new adaptive control strategy for stringent thermohygrometric indoor air requirements

In this paper a novel optimal Model Reference Adaptive Control approach, developed to tame the thermohygrometric behaviour of buildings as well as to guarantee the indoor comfort, is presented. The main advantages of the proposed method are: (i) no-need of a priori knowledge of the specific building dynamics due to climate, occupants’ behaviour, building use, envelope features and utility rates; (ii) robustness with respect to a large class of perturbations, external disturbances, nonlinear unmodelled dynamics or parameters uncertainty; (iii) ability to impose desired optimal dynamics; (iv) accurate regulation and fast tracking of indoor air temperature and humidity in the case of stringent requirements in special building spaces (e.g. hospitals, museums, laboratories, etc.).In order to investigate the effectiveness of the proposed method, the developed strategy has been implemented in the new release of a white-modelling building energy performance simulation code, called DETECt 2.3. The tool enables multi-zone building simulation analyses and is capable to dynamically predict: (i) spaces sensible and latent heating and cooling demands and loads; (ii) indoor air temperatures and humidity, as well as building envelope internal and external temperatures; (iii) the performance of phase change materials (PCM) embedded in building enclosures and for any layer configuration; (iv) the thermohygrometric comfort of occupants.In order to analyse the effectiveness and robustness of the proposed control strategy, several case studies have been carried out. They refer to some reference buildings with different geometry, use and construction materials (also including PCM integrated into the building envelope) simulated in different weather conditions. For each case study, both continuous and intermittent control system regimes have been considered. Results confirm the ability of the developed approach to achieve the selected indoor air temperature and humidity conditions in order to guarantee indoor comfort in uncertain conditions. The numerical analysis is complemented with the rigorous analytical proof of asymptotic stability.

Analysis of steady and target walking speeds in limit cycle walking

This paper presents the mathematical analysis of steady walking speed and target walking speed generation in 1-DOF limit cycle walking driven by time-settling control inputs. An actuated combined rimless wheel (CRW) model is introduced to analyse the steady walking state when the CRW is walking on level ground. First the initial and terminal boundary conditions driven by discrete stepwise control systems are analysed. The steady step period can be calculated and the target walking period can be generated by the formulas. Second we extend the mathematical analysis to \((n+1)\)-period stepwise control system and derive the general formula of the steady step period. Finally, the continuous piecewise control systems are analysed mathematically by discretizing the control input, and thus the boundary conditions can be analysed by the formula of \((n+1)\)-period stepwise control system. As a result, if the generated walking gait is single-step-cycle, the steady step period can be calculated and target walking steady speeds can be generated by our general formulas in the time-settling control systems.

Concept of Designing Systems for Monitoring Technical State of Rolling Mill Electric Drives

It has been proven that the introduction of the systems for continuous control of the equipment technical state is a necessary requirement of the modern maintenance of the critical equipment. The paper proposes the list of the processing facilities applied within the development systems for technical state control. The task of development of the system for recording, storing and displaying oscillographs of the automated electric drives of the wide-strip hot-rolling mill has been defined. The paper offers the analysis of the recording system based on the remote I/O controllers and the system with distributed industrial computers. The most informative-significant signals are listed. The network topology of the decentralized system implemented at the 2,500 mm wide-strip hot-rolling mill of OJSC Magnitogorsk Iron and Steel Works is suggested. Oscillographs of the main coordinates of the mill's electric drives obtained by means of the introduced system are provided.

컴포넌트기반 체계모의환경(AddSIM)에서 실행하기 위한 DEVS 모델 변환 방법

An AddSIM(Adaptive distributed and parallel Simulation environment for Interoperable and reusable Models) is an integrated engagement simulation environment with high-resolution weapon system models for estimation and analysis of their performance and effectiveness. AddSIM can simultaneously handle the continuous dynamical system models based on continuous time, and command, control(C2) and network system models based on a discrete event. To accommodate legacies based on DEVS(Discrete Event System Specification) modeling, DEVS legacies must first be converted into AddSIM models. This paper describes how to implement DEVS models on AddSIM. In this study a method of mapping from hierarchical DEVS models to AddSIM players was developed: The hierarchical DEVS model should be flattened into a one layered model and four DEVS functions of the model, external transition, internal transition, output and time advance, should be mapped into functions of the AddSIM player.

A complex line homotopy algorithm for coupled algebraic Riccati equations

This paper presents an algorithm based on a complex line homotopy mapping for the numerical solution of systems of coupled algebraic matrix Riccati equations which often met in continuous time control system design problems. Well-defined complex homotopy paths lead to solutions globally from independent initial conditions, and they are computed via continuous dynamic flow algorithms (ordinary differential equation solvers). Although the homotopy mapping is complex it is shown how it is possible in practice to obtain desired real solutions of certain definiteness even from zero initial conditions. Moreover, a scaling method is deployed within the algorithms for numerical enhancement and its effect to homotopy paths, convergence and stability is experimentally studied. In addition, a first-order perturbation analysis framework for the assessment of computed solutions is provided. Comparisons with other existing methods from the literature are made through several numerical examples considering mixed H|$_{2}$|/H|$_{\infty }$|⁠, Nash games and stochastic control system design problems, where the efficiency of the proposed algorithm is illustrated. It is worth noticing that algorithmic implementation and numerical experimentation with complex homotopies for the coupled algebraic Riccati equations under study appears to be absent the literature. Hence, the contribution of the present paper to related problems in systems and control.

Economic and environmental considerations in a continuous review inventory control system with integrated transportation decisions

Sustainability throughout supply chains is gaining more importance and re-planning inventory operations can help companies curb emissions. In this study, we present two bi-objective integrated continuous review inventory control and transportation models with less-than-truckload and truckload carriers. Solution methods to approximate the Pareto Frontiers are proposed. Numerical studies illustrate the effects of demand variance and lead time on expected costs and carbon emissions as well as the changes in expected costs and carbon emissions due to sustainability considerations. Sample examples illustrate the use of the methods to compare different carriers in terms of not only economic but also environmental considerations.

Discrete-continuous electromechanical control systems with passive adaptation

Issues in constructing discrete–continuous electromechanical control systems with functions of adaptation to changes of settings that influence the parameters and motion sensor characteristics, such as speed or position of an operating element of a mechanism that has been set in motion, have been discussed. Because the adapters of such systems do not participate directly in the correction of control action of electric drivers, such systems are called “conditionally adaptive” or “systems with passive adaptation.” Generally, passive adaptation systems allow significantly reducing the sensitivity of the closed-loop control systems of electric drives to variations of its parameters. However, such systems can also perform the functions of parametric adaptation of previous filters of electromechanical control systems or information-measuring converters, solving the tasks of constructing a reference change in a coordinate of a system. In this case, zero-order holds play a key role in the processes of conversion of information on signals of additive actions of electric drivers and motion sensors to the piecewise-continuous analog or digital signals. The present work shows that zero-order holds operating in the regimes with variable frequency of information sampling allow on to significantly extend the functionality of electric drives both with respect to the quality factor of control of electric drives with variable motor drive control and with respect to savings in time in processing of measured data due to the possibilities of data compression. The generalized functional structure of passive adaptive discrete-continuous electromechanical control systems with such zero-order holds is presented. In addition, simulation results in the Matlab/Simulink environment of passively adaptive system regulating the speed of a dc electric drive with a discrete proportional–integral speed regulator and quasi-invariant system of speed control with a discrete state regulator equipped with setting devices of intensity and speed sensors with zero-order holds that confirm the effectiveness of the proposed technical solutions are presented.

Control Systems Engineering in Continuous Pharmaceutical Manufacturing May 20–21, 2014 Continuous Manufacturing Symposium

This white paper provides a perspective of the challenges, research needs, and future directions for control systems engineering in continuous pharmaceutical processing. The main motivation for writing this paper is to facilitate the development and deployment of control systems technologies so as to ensure quality of the drug product. Although the main focus is on small-molecule pharmaceutical products, most of the same statements apply to biological drug products. An introduction to continuous manufacturing and control systems is followed by a discussion of the current status and technical needs in process monitoring and control, systems integration, and risk analysis. Some key points are that: (1) the desired objective in continuous manufacturing should be the satisfaction of all critical quality attributes (CQAs), not for all variables to operate at steady-state values; (2) the design of start-up and shutdown procedures can significantly affect the economic operation of a continuous manufacturing process; (3) the traceability of material as it moves through the manufacturing facility is an important consideration that can at least in part be addressed using residence time distributions; and (4) the control systems technologies must assure quality in the presence of disturbances, dynamics, uncertainties, nonlinearities, and constraints. Direct measurement, first-principles and empirical model-based predictions, and design space approaches are described for ensuring that CQA specifications are met. Ways are discussed for universities, regulatory bodies, and industry to facilitate working around or through barriers to the development of control systems engineering technologies for continuous drug manufacturing. Industry and regulatory bodies should work with federal agencies to create federal funding mechanisms to attract faculty to this area. Universities should hire faculty interested in developing first-principles models and control systems technologies for drug manufacturing that are easily transportable to industry. Industry can facilitate the move to continuous manufacturing by working with universities on the conception of new continuous pharmaceutical manufacturing process unit operations that have the potential to make major improvements in product quality, controllability, or reduced capital and/or operating costs. Regulatory bodies should ensure that: (1) regulations and regulatory practices promote, and do not derail, the development and implementation of continuous manufacturing and control systems engineering approaches; (2) the individuals who approve specific regulatory filings are sufficiently trained to make good decisions regarding control systems approaches; (3) provide regulatory clarity and eliminate/reduce regulatory risks; (4) financially support the development of high-quality training materials for use of undergraduate students, graduate students, industrial employees, and regulatory staff; (5) enhance the training of their own technical staff by financially supporting joint research projects with universities in the development of continuous pharmaceutical manufacturing processes and the associated control systems engineering theory, numerical algorithms, and software; and (6) strongly encourage the federal agencies that support research to fund these research areas.

Coordinated learning based on time-sharing tracking framework and Gaussian regression for continuous multi-agent systems

Applying multi-agent reinforcement learning (MARL) in continuous distributed control system is an attractive issue, because it entitles agents adaptively to construct a cooperative behavior, even if the dynamics of such distributed system is unknown a priori. However the implementation of MARL always suffers from dimension explosion, nonstationary learning, and generalization in continuous systems. This paper presents a continuous coordinated learning algorithm with time-sharing tracking framework (CCL-TT) to deal with these problems, in which the value function is dimension reduced to lighten dimension explosion, the time-sharing tracking framework (TTF) is developed to solve nonstationary learning, and Gaussian regression modeling is applied to realize generalization. With TTF, a macroscopic concurrent learning is set up to meet the requirements of temporal stationary condition in value learning and generalization. Finally the simulation illustrates how CCL-TT realizes cooperative learning without knowledge about the dynamics of the system, even with disturbance.

Closed-loop control for pediatric Type 1 diabetes mellitus

SUMMARY Closed-loop clinical trials have resulted in significant advances with continuous glucose monitoring and control systems modulating insulin delivery. Those trials were performed in closely supervised clinical research settings; while adults with Type 1 diabetes were initially targeted, studies in children with Type 1 diabetes have followed in both clinical research units and pediatric diabetes camps. These studies have been conducted as multicenter and multinational efforts. Pediatric studies have since been piloted in home settings overnight for control during sleep. The stage is now set for accelerating efforts, extending the number of patients enrolled, the amount of time during which the system is active daily and the duration of the clinical trials.

Analysis of Thermal State of Power Transformer of Captive Power Plant

It has been proven that the introduction of the systems for continuous control of the power transformer technical state predetermines the need for improvement of the methods for calculation of the thermal modes, insulation wear and remaining service life of the equipment. Disadvantages of the existing methods recommended by domestic and foreign regulatory documents are noted. It is appeared to be practically to consider parameters of the environment, thermal mode retention and non-linearity of the thermal characteristics. The structure of algorithm for calculating temperature charts according to the load parameters with regard to the influence of the above factors is proposed. The developed software is briefly specified, too. The ultimate purpose is to develop and study the improved model for thermal characteristic calculation designed for the systems of on-line monitoring transformer technical state.

Finite-time stabilisation of simple mechanical systems using continuous feedback

Stabilisation of simple mechanical systems in finite time with continuous state feedback is considered here. The dynamics are represented by generalised (local) coordinates. A general methodology to construct control Lyapunov functions that are Hölder continuous and that can be used to show finite-time stability of the feedback controlled system, is presented. This construction also gives the feedback control law, and results in the feedback system being Hölder continuous as well. Unlike Lipschitz continuous feedback control systems, the feedback control scheme given here converges to the desired equilibrium in finite time. Moreover, unlike discontinuous and hybrid control schemes, the feedback control law does not lead to chattering in the presence of measurement noise, does not excite unmodelled high-frequency dynamics, and can be implemented with actuators that can only deliver continuous control inputs. The advantages of continuous finite-time stabilisation over continuous asymptotic stabilisation of mechanical systems, has been described in some prior research on finite-time stabilisation of the double integrator. The finite-time stabilisation scheme given here generalises this prior research to multiple degree-of-freedom mechanical systems. A numerical comparison is carried out through numerical simulations on two example systems that are representative of a broad class of simple mechanical systems.

Subglottic secretion drainage and continuous control of cuff pressure used together save health care costs

Preventive strategies to reduce ventilator-associated respiratory infection (VARI) include the use of an endotracheal tube incorporating a lumen for subglottic secretion drainage (SSD) and a system for continuous control of endotracheal tube cuff pressure (CCCP). The health care costs associated with the combined use of these 2 measures aimed at preventing VARI are not known, however. The objective of this study was to determine whether the simultaneous use of these 2 preventive measures for VARI could save health care costs. We performed a prospective observational study of patients who needed mechanical ventilation in an intensive care unit. The health care costs considered here included only the costs of the endotracheal tube, cuff control, and antimicrobials used to treat VARI. The study cohort comprised 656 patients, including 241 with intermittent control of cuff pressure and without SSD (standard group), 260 with CCCP and without SSD (CCCP group), 84 with intermittent control of cuff pressure and with SSD (SSD group), and 71 with CCCP and SSD (CCCP + SSD group). The incidence of VARI and health care costs were lower in the CCCP + SSD group compared with the standard, CCCP, and SSD groups. The combined use of SSD and CCCP reduced the incidence of VARI and saved health care costs.

Conditions for the absence of cycles of the second kind in continuous and discrete systems with cylindrical phase space

Continuous and discrete indirect control systems with periodic vector nonlinearities are considered. One of the key problems concerning the asymptotic behavior of such systems is studied, namely, the existence of cycles in a cylindrical phase space. Multiparameter frequency-algebraic criteria for the absence in a cylindrical phase space of a system of cycles with given frequency are obtained.