Study of the Control System With the Smith Predictor and Autotuning Algorithm AT-2 for Thermal Control Objects With the Constant Speed Actuator

In the paper is highlighted the industrial objects as cars, spacecraft, telescopes, plotters, lasers, elevators, etc., which are described by the mathematical model with double astatism. These models of control objects have a double pole in the origin of the coordinate axes. In order to tune the PID controller to the model of object with double astatism, it was elaborated the tuning algorithm based on the maximum stability degree method with iterations. It was done the computer simulation of the automatic control system with the respectively model of object and PID controller and it was done the analysis of the obtained performance. The advantages of the maximum stability degree method with iterations were highlighted by the reducing calculations and time, which lead to the procedure simplification of the PID controller tuning.

In this paper, the design method of optimal control for the conveyor-based transport system, when the quality criterion contains a variable delay in the controls, has been considered. The task of optimal control has been set and the Hamiltonian of the system has been written taking into account the delay in the controls. In the design of optimal control by the flow parameters of the transport system, a control object model containing partial differential equations was used. The mechanism that forms a variable value of the transport delay in the flow parameters of the transport system has been shown. Two characteristic modes of the conveyor system functioning are considered as follows: a transient state, when the value of the linear density at the transport system output is determined by the initial distribution of material along the transport route, and a steady-state state, when the value of the linear density at the transport system output is determined through the values of the movement speed of the conveyor belt and the intensity of the material at the conveyor section input. Equations that make it possible to calculate the controls of the flow parameters of the transport system for which the Hamiltonian of the system satisfies the Hamilton–Jacobi equation have been provided. Controls of the flow parameters are synthesized for the case when the phase coordinate does not reach the limits. It is shown that for the synthesis of controls, it is necessary to predict the magnitude of the output flow from the transport system.

The control strategy research of the time-delay system is a focused issue in the control field. In order to furthermore improve the performance of the first-order time-delay inertial system, firstly, a new Smith predictor structure is proposed, which solves the constraint that the conventional Smith predictor needs to match the actual object model. Secondly, the performance and parameter function of the new Smith predictor are discussed in theory to provide the basis for parameter tuning. Finally, a new Smith predictor combined with linear active disturbance rejection control (LADRC) is proposed to solve the problem that the two input signals of the linear extended state observer (LESO) are not synchronized on the time scale, and the stability of the new Smith + LADRC time-delay control system is proved theoretically for known and unknown controlled complex objects. Simulation analysis is conducted to verify the robustness of the proposed strategy under the condition of the different parameters. The results indicate that the proposed strategy has better performance than the conventional method in response speed, overshoot, adjustment time, and stability.

The paper is devoted to the influence of transfer function zeros on state feedback controller parameters. Nowadays, during the modal control system design process, the most attention is paid to the analysis of transfer function poles. If transfer function zeros are located closely to the poles, the control object tends to singularity, when the influence of the input control signals to the output signals becomes weaker. This fact leads to the designing of state-space controllers with extremely high values of control coefficients. Available methods for selecting the desired poles of closed loop systems are represented by the following variants: quantitative evaluation of the controllability and observability of object models and object model reduction. These methods have some disadvantages: dependence on the state-space representation of the control object model, ignoring some parts and characteristics of the control object model. In this paper, to analyze the state feedback controller parameters the invariant of the state-space representation characteristic is used – catalecticant (Hankel) matrix. As a result, it was found that control coefficients of the state feedback controller are inversely proportional to the determinant of the catalecticant matrix of the control object, and the determinant of the catalecticant matrix is equal to the resultant of transfer function polynomials. A method of converting the block diagram of the control object model using the residues of the transfer function was suggested. As a result of the conversion, poles, which cause high values of control coefficients, are isolated as a multiplicative uncertainty in the object model structure. The robust control theory can be used for control system designing with such organization of the control object.

The paper is focused on systems with delay terms at the left (and the right) side of differential equations. Analysis and synthesis of delay systems can be conveniently studied through a special ring of RQ-meromorphic functions. The control methodology is based on a solution of Diophantine equations in this ring. Final controllers result in the Smith predictor like structure. Controller parameters are tuned through a pole-placement problem as a desired multiple root of the characteristic closed loop equation. The methodology is illustrated by a stable second order transfer function with a dead-time term. Then the paper brings an autotuning method as a combination of biased-relay feedback estimation and the proposed algebraic control design. The developed approach is illustrated by examples in the Matlab and Simulink environment.

Design of a Robust Fractional Order Controller for Burning Zone Temperature Control in an Industrial Cement Rotary Kiln

A Dead Time Compensator Based on Linear Algebra (DTCLA)

An experimental application of time delay compensation techniques to distillation column control

The article examines the peculiarities of the organization of internal control at property rental enterprises. The main elements of the internal control system of property rental enterprises are determined – control environment, goals, functions, tasks, principles, subjects, objects, control procedures, methods and users of control information. The organization of the internal control system of rental business enterprises is defined as a set of actions aimed at ensuring the effective functioning of a set of interconnected and interdependent elements, thanks to which internal control acquires rational characteristics necessary for the implementation of the tasks and achievement of the goals set by the owners and management of the enterprise. Attention is drawn to the fact that approaches to the organization of internal control will depend on the policy followed by the owners and management of the enterprise in order to establish an effective mechanism for the functioning of this control system. The purpose and goals of internal control in the information provision of the management system of the decision-making process in order to create conditions for the effective operation of rental business enterprises are specified. Determining the functions of internal control. It is recommended to start the organizational process with the setting of control tasks, based on which the control objects and the list of control procedures that will be used in the process of their verification are specified. The need to implement all stages of the organization of internal control in compliance with the key principles of control was considered. Attention is paid to the world practice of using the COSO model of internal control construction, with the definition of the conceptual basis of risk management and the goals it is focused on achieving. The importance of identifying risks associated with the functioning of control objects of property rental enterprises is revealed, which directs the attention of internal control to those areas where financial losses are most likely to occur. Attention is focused on the need to define the circle of persons who carry out control, i.e. control subjects who will perform specific tasks of control of property rental activities. It is recommended to distribute powers between control subjects in accordance with job duties in the organizational structure of the enterprise or internal control service, with the establishment of information links between all control subjects. The possibility of organizing internal control at rental business enterprises under outsourcing conditions was considered.

The controlled atmospheric re-entry associated with the precision soft-landing of Reusable Launch Vehicles (RLVs) on Earth is very challenging as it depends on multiple parameters [1]. Over the last decade, the cost-effectiveness of such a technology has been finally demonstrated with the successful recoveries of SpaceX’s Falcon 9 first-stage rocket first [2], then followed by other companies such as the Rocket Lab’s Electron micro-launcher [3]. This breakthrough has been made possible by the development of advanced and robust computational methods able to generate in real time the flight conditions and to command the optimal vehicle's deflections accordingly to achieve a safe pinpoint landing. Indeed, during an Earth atmospheric re-entry, the vehicle is subjected to fast system dynamics changes partly induced by external loads associated with the terrestrial environment (e.g., lift, drag, wind and gusts), but also by the actuation commands to answer the landing constraints satisfaction and the vehicle integrity preservation. All those involve uncertainties and nonlinearities, which lead to vehicle’s instability and therefore give reason why for a highly performant Guidance, Navigation and Control system implementation [4]. More particularly, one of the critical aspects is the design of a robust control strategy capable of counteracting the previously defined disturbances and uncertainties while satisfying the strict accuracy requirements associated with the pinpoint landing [5]. As demonstrated by the current state-of-the-art on control design for launchers [6-7], the classical linear control theory represents a rich heritage with a lot of applications. This choice was motivated by its relative easiness of implementation and the possibility to use gain-scheduling techniques to adapt to nonlinear systems. Nevertheless, these techniques are well-adapted to the control system design of single-input single-output systems, such as for example a reusable rocket using a Thrust Vector Control (TVC) system as the unique actuator. The implementation of multiple-input multiple-output control systems becomes then complex since every channel is addressed in a single-loop fashion. This capability is however required for the future generation of reusable rocket, using also aerodynamic steering based on fins in addition to the TVC system for enhancing control authorities. Moreover, model uncertainties are not accurately considered in the design process, developed only with nominal conditions and stability margin requirements. For all these reasons, it results in an extensive (both in terms of time and cost) Verification and Validation campaign with many iterations and Monte-Carlo analyses to assess the performance and robustness of the control system. To overcome these drawbacks, the H-infinity family of methods, introduced a few years ago [8], provides with a powerful solution for robust control design. It relies on defining the control requirements in the frequency domain in terms of weighting functions and minimising the maximum gain of the resulting weighted system from the exogenous inputs to the outputs to be controlled. Moreover, the control-plant interaction is modelled through a Linear Fractional Transformation (LFT) representing the feedback action. Finally, the structured H-infinity method [9] allows to directly impose a specific control structure – like a Proportional-Integral-Derivative (PID), enabling the re-use of gain-scheduling techniques – and to consider parametric uncertainties for enhanced robustness. This paper studies the synthesis of a robust control system via structured H-infinity for the RLV atmospheric re-entry problem. First, the nonlinear 6-Degree-of-Freedom (6-DoF) RLV re-entry dynamics are simplified into a linear model and then linearised along a reference trajectory to get the nominal LFT of the system, then augmented with parametric uncertainties. The model covers the atmospheric re-entry and vertical landing of a first-stage rocket equipped with a TVC system and steerable planar fins. The controllers are built at different points of the re-entry trajectory, using the structured H-infinity framework through PID-like structures. Weighting functions considering the control objectives and requirements of a realistic RLV re-entry scenario are implemented. A robust stability analysis of the obtained system is performed via classical stability margins and structured singular value. Finally, the controllers are gain-scheduled and validated via Monte-Carlo analyses, using a nonlinear 6-DoF RLV re-entry dynamics simulator equipped with successive convex optimisation guidance. The performance of the resulting guidance and control architecture is compared with the baseline developed in previous works [10], using a TVC system only and classical linear feedback control through gain-scheduled PID controllers. This study lies within the ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) project, an innovative training network funded within H2020.

The design and implementation of systems for automatic control of changes in the coordinates of the state and the output variables of power and energy installations consist of several successive stages, which implementation is widely used mathematical modeling. One of the most important such stages is the development of the created system (regulator) on a semi-natural stand. Such a stand usually contains a sample of a system with physically implemented measuring channels, and the control object and actuators are made in the form of a real-time computer mathematical model (stand-simulator). The problem is to resolve the contradiction between the requirements of the adequacy of the computer experiment to the real operating conditions and the capabilities of the simulator stand because the mathematical model of the control object is deterministic. In real conditions, there are random disturbances, which determine the random nature of the original-measuring coordinates of the control object. The use of known statistical modeling techniques is limited by the stationary requirements because the controlled objects are multi-mode. A solution to this contradiction is proposed by applying new information technology, which consists of the consistent implementation of the stages of preliminary approximation of time series of deviations of such variables from the formed approximation model, and the stage of statistical modeling. As a statistical model of random processes of deviations of such variables from the formed approximation model, the Markov process model is proposed, which considers the possible correlation of the initial data. The application of the approximation model provides the conditions of stationary and correctness of the proposed model. The applied problem of modeling the change of parameters of the technical conditions of a multi-mode technical object in long-term operation on the basis of the proposed model and experimental data is solved.

This work proposes the use of a Smith predictor with jitter transport delay adaptation to feedback control systems on which control loops are closed through an IP network. The well know Smith predictor is efficient to compensate constant transport delay but IP networks presents jitters which disturb the performance of the predictor. Therefore, together to the predictor it is implemented a new compensation way to this typical jitter of these networks. This compensation has a data structure in order to store values from the output of the predictor, in order to the right value be read to from it to compare with to the value from the system feedback. The value is chosen based in the last delay in the control loop. The proposed approach was validated via simulation and experimental results are presented in the paper.

W e st udy the solution of the so-called maximum speed problem of a linear control system, in which, unlike the classical optimal speed problem with a relay-type control, a linear control algorithm is determined for a linear object that provides the maximum speed of the system. It is of practical importance due to the widespread practical application of linear co ntrol laws. The problem is formulated in relation to continuous, one-dimensional high-order control objects described by the corresponding transfer function or an equivalent system of ordinary differential equations in a certain phase space. The time of the transition process t tp of the designed system is understood in the sense of the classical theory of automatic control and is determined using the zone D = s pr 4,321 %, equal to the given (desired) value of the overshoot of the synthe si zed s ystem. This overshoot corresponds to an oscillatory link with a damping coefficient √ 2/2 — the Butterworth filter of the second order. Accordingly, the maximum performance problem is put in the following formulation: it is required to fi nd a linear feedback algorithm that provides the closed control system with a given astatism order n a and transferring the control object from the initial state to the final one, determined by the constant signal of the regulator’s task, with the minimum value of transient time t tp and set value overshoot s = s pr when performing a constraint on the control signal |u(t)| m u max . At present, this problem has been solved by an approximately algebraic method of synthesizing linear control systems in determining the desired transfer function of a projected closed system based on typical (reference) normalized transfer functions (NTF). The approximate nature of the decision is determined by the fact that the NTF used in the synthesis of high-speed systems are established empirically. This paper proposes a mathematically sound solution to the problem of maximum speed using the theory of analytical design of optimal controllers (ADOC). The maximum speed and set limits on the overshoot and the value of the control signal in the synthesized system are provided by the proposed method for selecting the weights of the quadratic quality functional. We emphasize that the proposed method for the synthesis of high-speed systems, in contrast to the algebraic method, is applicable to a wider class of control objects: both minimal-phase and non-minimal-phase, as containing zeroes, and not. The method is illustrated by an example of the synthesis of a high-speed fourth-order control system containing the results of its simulation.

Objectives. The problem of functional verification of control devices with respect to their design specification is considered. When solving the problems of implementing and testing of discrete systems, one has to deal with the presence of parallelism in the behavior of interacting control objects, which is also displayed in the assignment for designing control systems. The aim of the work is to develop a method for simulating descriptions of such systems, which allows their behavior testing dynamically on the area limited by their possible functioning.Methods. The paper considers a class of control systems with parallelism of the processes occurring in them, which permits linearization of their execution. To specify the behavior of such control systems, it is proposed to use the PRALU language of parallel control algorithms, which is based on Petri nets and which allows to order events occurring during the device operation. An object-oriented approach to simulation of the description of the control algorithm at the transaction level is proposed. For this purpose, a TLM (Transaction-Level Modeling) model has been developed for describing the devices with behavior parallelism in PRALU language. The transaction level model describes a system as a set of interacting processes that run in parallel and determine the behavior of the system over time.Results. The key concepts of the TLM model for simulating the descriptions of control algorithms in the PRALU language are defined: data structure, transactions, processes, and a barrier mechanism for synchronization of parallel processes. A method is proposed for transforming the description of an algorithm in the language into a TLM model, which is based on the representation of language operations as compositions of elementary operations that are performed sequentially. The set of these operations forms the basis for the algorithmic decomposition of a parallel algorithm in PRALU language into intermediate language program that is executed strictly sequentially. Translators of this program into the Verilog and C languages have been developed, the results of their compilation are simulators of the behavior of control system.Conclusion. The proposed simulation method can be used to create a test bench for functional verification of the circuit implementation of control devices with behavior parallelism. In this case, test sequences for verifying the circuit implementation can be generated dynamically – in the process of simulating the description of the algorithm in the PRALU language directly the control device or system, which include the control algorithm and the algorithms of controlled objects behavior.

Mass balance control of crushing circuits