Smith Predictor Control Research Articles

An Improved Lag-Time Compensation Technique in Distributed Networked Control System based on Smith Predictor

The geographically distributed feedback control loops connected via communication network elucidate the core of networked control system (NCS), wherein different users spread all over the world can regulate, direct and command the components of control system located at distant location. The proficiency of NCS provides sceptre to its user and multifaceted assignments are successfully endowed through it. The ascendancy of NCS is lowered through inconspicuous delays which destabilize the system. The induction of delays in the network lead to the proscription of packet delivery, bandwidth utilization and stable system response. In this manuscript Smith predictor is modified using Markov approach and Kalman estimation algorithm. The scheme has been implemented by using Matlab/ Simulink software for delay compensation. Performance analysis shows the robustness of modified Smith-Predictor controller in comparison to classical Smith predictor controller and proportional-integral-derivative based controllers.

Certain Investigation Of Real Time Networked Control Dc Motor Using Smith Predictor

In this paper, DC motor is controlled by direct structure Networked Control System (NCS) with smith predictor control strategy. Mathematical model of DC motor is identified by empirical model building and estimated Round Trip Time Delay (RTT) is considered as time delay which is induced by network. Delay time which is induced in Networked DC motor is compensated with the smith predictor controller then the designed controller algorithm is comparatively analyzed with conventional PI controller. The simulation results are formulated for identified motor model with real time network. In addition to that the hardware fabrication of real time Networked DC motor has been developed and the results of both the simulation and hardware implementation are compared.

Analytical tuning of 2‐DOF smith predictor control scheme for DC‐DC boost converter: A process control perspective

AbstractStringent voltage regulation in a DC‐DC boost converter is a classical engineering problems in theory of power conversion. Voltage Mode Control (VMC) of boost converter is difficult for two principal reasons. First and foremost, of these two reasons, is the converter's non‐minimum phase (NMP) behavior that arises due to the presence of the dynamic right half plane zero (RHPZ) in control to output (c2o) transfer function in VMC. Second reason is the presence of parametric uncertainties* in converter during its continuous conduction mode (CCM) operation. This paper combines theory of smith predictor with boost converter for (i) analytically computing gains of PID controller, (ii) design of a low pass filter to deal with challenges posed by dynamic RHPZ. This two degrees of freedom (2‐DOF) control scheme is analytically derived as a function of the converter's parameters. Gains of PID controller, deduced in terms of circuit's parameter, are used in sequel for extensive simulation analysis of the converter's control loop. Results in this paper establish that the proposed 2‐DOF‐SP outperforms certain well known control schemes used in regulating output voltage and disturbance attenuation in boost converter.

State Feedback Temperature Control Based on a Smith Predictor in a Precalciner of a Cement Kiln

This paper proposes the design of a state feedback Smith predictor controller (SFC-SP) for the effective temperature control in a precalciner of a cement rotary kiln. The dynamic model of this process is obtained from real-time data by applying a system identification procedure. This identification procedure yields a fourth order with dominant time delay transfer function. A state feedback controller combined with a Smith predictor is therefore designed which behaves effectively. Simulated results compare the performance of the proposed controller with a standard PID controller. Two performance indexes have been used in this comparison: the integral absolute error (IAE), and the control effort (EU). Simulations show that the proposed controller provides lower values of these indexes and, therefore, outperforms the standard PID controller in terms of performance and accuracy

Control strategy with multivariable fault tolerance module for automatic intravenous anesthesia.

In the anesthesia automation, an automatic propofol infusion system uses Bi-spectral Index Signal (BIS) as a primary feedback signal to manipulate propofol dose. However, the BIS signal may be suspended for some time due to poor EEG signal quality, noise, and many other factors. Therefore, BIS signal failure may be the main cause of inadequate propofol infusion. This fact motivates the need for integration of multivariable fault tolerance module (MFTM) and fractional-order Smith predictor controller to avoid adverse reactions of inadequate propofol dosing during BIS failure. Smith Predictor control strategy is sufficiently robust to predict feedback BIS during BIS failure via patient pharmacological modeled BIS. However, modeled BIS may not provide a guarantee of adequate propofol infusion during BIS failure and especially in the presence of hypotension and hypertension. Thus, the proposed control strategy is designed with MFTM to detect BIS sensor fault and to estimate feedback BIS during BIS failure. Further, the proposed control strategy is designed with a multivariable pharmacological patient model to analyze the cross effect of propofol infusion on BIS and hemodynamic variables. The robustness of the proposed control strategy is tested in the presence of noxious surgical stimulation, BIS sensor fault and heavy hemodynamic disturbance. The pharmacological parameters and recorded signals of 30 patients during various surgeries have been used to validate simulated results. The performance of the proposed control strategy assures optimization and smooth propofol infusion during BIS failure. The proposed system provides stability for a wide range of physiological parameters range. The proposed scheme maintains smooth BIS and MAP signal despite the delay, BIS sensor fault, and surgical disturbances.

Decoupling Adaptive Smith Prediction Model of Flatness Closed-Loop Control and Its Application

Flatness control system is characterized by multi-parameters, strong coupling, pure time delay, which complicate the establishment of an accurate mathematical model. Therefore, a control scheme that combines dynamic decoupling, PI (Proportion and Integral) control and adaptive Smith predictive compensation is proposed. To this end, a dynamic matrix is used to decouple the control system. A multivariable coupled pure time-delay system is transformed into several independent generalized single-loop pure time-delay systems. Then, a PI-adaptive Smith predictive controller is constructed for the decoupled generalized single-loop pure time-delay system. Simulations show that the scheme has a simple and feasible structure, and good control performance. When the mathematical model of the control system is inaccurate, the control performance of adaptive Smith control method is evidently better than that of the ordinary Smith control method. The model is successfully applied to the cold rolling production site through LabVIEW, and the control accuracy is within 5I. This study reveals a new solution to the problem of coupled pure time-delay in flatness control system.

System Identification Based Controller Design for Friction Stir Welding Process During Joining of Aluminium Metal Matrix Composites

Friction Stir Welding (FSW) process was initially implemented by modifying the milling machines. With the advancements in robotics and automation, movement along three primary axes are made controllable using computer integration. FSW being a temperature-dependent process, the temperature at the weld zone affects the weld quality since the microstructure is totally altered by the temperature variations. If welding is done at constant process parameters by ignoring the process disturbances, it would also result in undesirable material properties. From research studies, it is understood that tool pin position and spindle speed are significant process parameters contributing to heat generation during the joining process. In this study, an attempt is made to control the spindle speed of the rotating tool by measuring tool-workpiece interface temperature and vibrational disturbances during joining of Aluminium Metal Matrix Composite (Al-MMC) plates. The system model is estimated from the experimental data using the concept of system identification. Followed by, a Smith Predictor control scheme is developed and validated in a closed loop FSW system to examine the tensile strength.

Study on Control Scheme of Quartz Fiber Prefabricated Rod Production Line

PSOD process has serious hysteresis phenomenon and belongs to the large hysteresis system. On the basis of analyzing the working mechanism of the system, the PID control, Smith predictive control and fuzzy control are combined to control the system. Simulation results show that the proposed method has better dynamic performance than the traditional PID control method, regardless of the given input or interference. The conclusion is valuable for the safe operation and control of time-delay systems.

Auto-tuning Smith-predictive Control of Delayed Processes based on Model Reference Adaptive ControllerAuto-tuning Smith-predictive Control of Delayed Processes based on Model Reference Adaptive Controller

Auto-tuning Smith-predictive Control of Delayed Processes based on Model Reference Adaptive ControllerAuto-tuning Smith-predictive Control of Delayed Processes based on Model Reference Adaptive Controller

Modified two-degree-of-freedom Smith predictive control for processes with time-delay

This article proposes an improved two-degree-of-freedom Smith predictive control method for typical industrial control systems. Smith predictive control is a classic control strategy designed for systems with pure lag. As an extension of Smith predictive control, internal model control can solve the time-delay problem effectively and make the controller design simple. Based on the two control algorithms, an enhanced control method with modified control structure is developed in this paper. In the design scheme, the set-point tracking and the disturbance rejection characteristics are decoupled, such that the set-point tracking and disturbance rejection controllers can be designed independently to achieve better control performance. The obtained control strategy possesses simple and convenient parameter tuning procedures. The validity of the proposed scheme is verified through theoretical analysis and simulation comparison with other control methods, and the results indicate that the proposed strategy shows better performance on set-point tracking and disturbance rejection.

Robust filtered Smith predictor for processes with time-varying delay: A simplified stability approach

This paper presents a family of simplified stability conditions for the filtered Smith predictor control of uncertain systems with time-varying delay. The delay can vary arbitrarily, but its maximum value is assumed to be bounded. Simple design rules are proposed to ensure robust stability in the presence of time-varying delay and model uncertainty. Frequency analysis and design methods can be directly used. Moreover, if (i) the process is open-loop stable and (ii) the closed-loop system without time-varying delay is stable for a given filtered Smith predictor controller, then the robustness filter can always be re-designed to recover robust stability in the presence of any bounded time-varying delay. It is shown that the main results can be extended to multivariable systems. Simulation examples and an experimental case study are presented to illustrate the benefits of the proposed stability conditions and design rules.

Simulation research on the grid connected generation system of solar thermal power generation

Objective: To improve the efficiency and stability of the solar thermal power generation system, and promote the optimization and development of solar thermal power generation grid connection. Methods: The working principle of the heat exchanger in the heat storage system is analyzed. Combined with the technological requirements of the system, the mathematical model of the heat exchanger is established by the mechanism modelling method. According to the inherent characteristics and control requirements of the heat storage system, the control schemes are proposed. The control strategies of different control algorithms, such as single-loop control, Smith predictive compensation control, cascade-Smith control, and feedforward-cascade-Smith control, are designed and adopted. The simulation model is established to obtain step response waveforms of different control systems. The advantages and disadvantages of different control strategies are comprehensively analyzed and compared. Results: After introducing the superheated steam mass-flow disturbance, the error of the single-loop control system increases. After adjusting the system to restore the oscillation state, the system error is high (10.24%). Smith predictive compensation control system fluctuates, with a peak time of 548 seconds

Adaptive Smith Predictor for Teleoperation of UAVs with Time-varying Internet Delay

Time delay in a networked control system can negatively impact the performance of the system. Dynamic networks with unknown and varying latency such as the Internet are studied. Also, experiments with teleoperation of drones and communication loops through the Internet are conducted. Smith Predictors are well known for their ability to handle time delay. Smith Predictor controllers perform well when modeled accurately and when the delay is known. The proposed method combines a delay estimation technique based on characteristic roots of delay differential equations to measure the delay with an Adaptive Smith Predictor. When the delay parameter is adjusted correctly, the negative effects caused by delay are significantly reduced. The proposed method performs satisfactory for networked systems with unknown delay and the results are validated through simulations and experimentation.

Set Point Weighted Modified Smith Predictor for Higher Order Integrating Processes with Time Delay

This Paper Presents About The Synthesis Of Two-Degree-Of-Freedom Control Structure Based On Modified Smith Predictor Control For Higher Order Integrating Processes With Time Delay. This Control Synthesis Is Done Based On Chengqiang Yin Method. It Has Two Pid Controllers- One Is Set Point Tracking Controller Based On Direct Synthesis Method And The Other Is Disturbance Rejection Controller Based On Imc Principle. In This Work, A Set Point Weight Is Added With Pid Controller To Reduce Peak Overshoots And Settling Time In The Modified Smith Predictor. Two Simulation Examples Are Given To Demonstrate The Validity Of This Method.

A Cerebellum-Inspired Learning Approach for Adaptive and Anticipatory Control.

The cerebellum, which is responsible for motor control and learning, has been suggested to act as a Smith predictor for compensation of time-delays by means of internal forward models. However, insights about how forward model predictions are integrated in the Smith predictor have not yet been unveiled. To fill this gap, a novel bio-inspired modular control architecture that merges a recurrent cerebellar-like loop for adaptive control and a Smith predictor controller is proposed. The goal is to provide accurate anticipatory corrections to the generation of the motor commands in spite of sensory delays and to validate the robustness of the proposed control method to input and physical dynamic changes. The outcome of the proposed architecture with other two control schemes that do not include the Smith control strategy or the cerebellar-like corrections are compared. The results obtained on four sets of experiments confirm that the cerebellum-like circuit provides more effective corrections when only the Smith strategy is adopted and that minor tuning in the parameters, fast adaptation and reproducible configuration are enabled.

Temperature based spindle speed controller during friction stir welding of aluminium metal matrix composites

PurposeThis paper aims to investigate two control mechanisms on the two parameters, namely, spindle speed and tool pin position, while performing friction stir welding (FSW) for aluminium metal matrix composites (Al-MMC) using the concept of system identification.Design/methodology/approachFSW is a feasible choice for joining of Al-MMC over the fusion welding due to the formation of the narrow heat-affected zone and minimizing the formation of intermetallic compounds at weld interface. The goal in FSW is to generate enough thermal energy by friction between the workpiece and rotating tool. Heat energy is generated due to mechanical interaction because of the difference in velocity between the workpiece and rotating tool. The generated heat is proportional to the tool pin position and the spindle speed. In the present work, a Smith Predictor Control scheme and adaptive control scheme are developed during joining of Al6061/SiC/B4C Al-MMC by FSW. Adaptive controller is developed to control the tool pin position while Smith Predictor control is developed to control the spindle speed. Initially, the Al-MMC plates are prepared at five combinations of SiC and B4C reinforcements and welded at three level parameter settings followed by tensile testing. The experimental data are used in estimating the plant transfer function model using system identification. The control schemes are then developed for the estimated plant model and the same are validated using a standard PID controller. In both the control schemes, PID controller results in a sluggish response. Experimental validations are performed for the developed control schemes followed by microscopic studies of the weldments.FindingsIn both the control schemes, PID controller results in a sluggish response. Experimental validations are performed for the developed control schemes followed by microscopic studies of the weldments.Research limitations/implicationsResults from the study concluded that the developed MRAC and Smith predictor scheme effectively controlled the vibrations and spindle speed effectively.Originality/valueIt is observed that the scanning electron microscopy micrographs of the Al-MMC’s welded using developed control schemes resulted in good boding with homogenous distribution of reinforcement particles.

Application of Improved Fuzzy-Smith Controller in the Control System of Cement Rotary Kiln

Rotary cement kiln is a large time delay and inertia component. It is a typical problem in industrial process control, so advanced control methods should be adopted. This paper designs an improved Fuzzy-Smith controller. It combines Fuzzy with improved Smith predictor control method. Smith predictor algorithm compensates for the time delay and Fuzzy control is used to enhance the robustness of the system. The simulation results show that the improved Fuzzy-Smith controller owns stronger robustness and much better control quality. And it is an appropriate and simple control method for the system with pure lag.

Identification and control design for a class of non-minimum phase dead-time systems based on fractional-order Smith predictor and genetic algorithm technique

The design of Smith predictor (SP) controllers has been largely investigated in the literature to solve fractional-order dead-time systems control problems; this is due to its robustness in presence of modeling uncertainties and measurement noises. In this paper, a new SP control strategy is proposed for a special class of non-minimum phase dead-time systems. This controller can be designed only by imposing a new fractional-order model and new robust controller in the modeling and synthesis stages. A fractional multi-low-order dead-time (FMLODT) model is accordingly proposed in the SP modeling stage, where an actual process behavior is well ensured by high model accuracy. The proposed fractional model parameters are identified by an adequate optimization tool based genetic algorithm. Furthermore, a robust fractional order controller based FMLODT model is synthesized, its structure is analytically determined through a three terms fractional-order reference (TTFOR) model. The proposed fractional controller parameters are tuned according to some guidelines available in the literature. Thus, two main contributions are proposed in this work: the first one consists of introducing a general framework for the SP modeling scheme. This is ensured by the proposed FMLODT model, which enhances significantly the modeling accuracy compared to the existing models in the literature. The second innovation consists of proposing a general framework for the controller design step in the SP scheme. This is guaranteed by the proposed TTFOR model, which improves significantly the trade-off between the two contradictory goals: performance and robustness. To highlight the proposed strategy of good performances, both the new fractional order model and the classical controller are applied on the minimum phase dead-time systems. The obtained simulation results illustrate the performance and improvement of the proposed model comparatively to preceding works.

Advanced Simulation and Analysis of MIMO Dead Time Compensator and Predictive Controller for Ethanol Distillation Process

Abstract This paper analyses advanced control strategies in an ethanol production facility. A Matlab computing platform integrated with Aspen Hysys was developed to simulate industry practice. Two types of advanced control system were used in this study: a Model Predictive Control and a Dead Time Compensator. In particular, an Infinite Horizon Predictive Controller (IHMPC) and Filtered Smith Predictor (FSP) controller were designed to ensure ethanol production into a desired quality range under feed variations as disturbances. Performance indexes and computational processing time were used to evaluate the control systems. This work offers different and satisfactory solutions for several application scenarios, taking in account the main characteristics of each controller.

Improved Cascade Control System for a Class of Unstable Processes with Time Delay

An improved cascade control scheme is proposed based on modified Smith predictor for controlling a class of unstable processes with time delay. The proposed control structure consist three controllers of which the secondary loop has one controller and the primary loop has two controllers. The secondary loop controller is designed according to Internal Model Control (IMC) principles. The primary loop set point tracking controller and disturbance rejection controller are designed using the same procedure based on modified Smith predictor control structure. An analytical method on the basis of the Internal Model Control design principle is adopted for the two controllers which reduces complexity in design. The two controllers in primary loop are designed as proportional, integral and derivative (PID) controller cascaded with a lead-lag filter. Moreover, suitable values are recommended for the three controllers based on extensive simulations. Simulations studies are carried out to demonstrate the effectiveness of the proposed method.