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1
Yoo, C. K., J. H. Cho, H. J. Kwak, S. K. Choi, H. D. Chun, and I. Lee. "Closed-loop identification and control application for dissolved oxygen concentration in a full-scale coke wastewater treatment plant." Water Science and Technology 43, no. 7 (2001): 207–14. http://dx.doi.org/10.2166/wst.2001.0426.
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The objective of this paper is to apply a closed-loop identification to actual dissolved oxygen control system in the coke wastewater treatment plant. It approximates the dissolved oxygen dynamics to a high order model using the integral transform method and reduces it to the first-order plus time delay (FOPTD) or second-order plus time delay (SOPTD) for the PID controller tuning. To experiment the process identification on the real plant, a simple set-point change of the speed of surface aerator under the closed-loop control without any mode change was used as an activation signal of the identification. The full-scale experimental results show a good identification performance and a good tracking ability for set-point change. As a result of improved control performance, the fluctuation of dissolved oxygen concentration variation has been decreased and the electric power saving has been accomplished.
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Seban, Lalu, Namita Boruah, and Binoy K. Roy. "Development of FOPDT and SOPDT model from arbitrary process identification data using the properties of orthonormal basis function." International Journal of Engineering & Technology 7, no. 2.21 (2018): 77. http://dx.doi.org/10.14419/ijet.v7i2.21.11840.
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Most of industrial process can be approximately represented as first-order plus delay time (FOPDT) model or second-order plus delay time (FOPDT) model. From a control point of view, it is important to estimate the FOPDT or SOPDT model parameters from arbitrary process input as groomed test like step test is not always feasible. Orthonormal basis function (OBF) are class of model structure having many advantages, and its parameters can be estimated from arbitrary input data. The OBF model filters are functions of poles and hence accuracy of the model depends on the accuracy of the poles. In this paper, a simple and standard particle swarm optimisation technique is first employed to estimate the dominant discrete poles from arbitrary input and corresponding process output. Time constant of first order system or period of oscillation and damping ratio of second order system is calculated from the dominant poles. From the step response of the developed OBF model, time delay and steady state gain are estimated. The parameter accuracy is improved by employing an iterative scheme. Numerical examples are provided to show the accuracy of the proposed method.
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Wang, Runzhi, Xuemin Li, Yufei Liu, Wenjie Fu, Shuang Liu, and Xiuzhen Ma. "Multiple Model Predictive Functional Control for Marine Diesel Engine." Mathematical Problems in Engineering 2018 (2018): 1–20. http://dx.doi.org/10.1155/2018/3252653.
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A novel control scheme based on multiple model predictive functional control (MMPFC) is proposed to solve the cumbersome and time-consuming parameters tuning of the speed controller for a marine diesel engine. It combines the MMPFC with traditional PID algorithm. In each local linearization, a first-order plus time delay (FOPTD) model is adopted to be the approximate submodel. To overcome the model mismatches under the load disturbance conditions, we introduce a method to estimate the open-loop gain of the speed control model, by which the predictive multimodels are modified online. Thus, the adaptation and robustness of the proposed controller can be improved. A cycle-detailed hybrid nonlinear engine model rather than a common used mean value engine model (MVEM) is developed to evaluate the control performance. In such model, the marine engine is treated as a whole system, and the discreteness in torque generation, the working imbalance among different cylinders, and the cycle delays are considered. As a result, more reliable and practical validation can be achieved. Finally, numerical simulation of both steady and dynamic performances of the proposed controller is carried out based on the aforementioned engine model. A conventional well-tuned PID with integral windup scheme is adopted to make a comparison. The results emphasize that the proposed controller is with stable and adaptive ability but without needing complex and tough parameters regulation. Moreover, it has excellent disturbance rejection ability by modifying the predictive multimodels online.
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Muresan, Cristina I., and Clara M. Ionescu. "Generalization of the FOPDT Model for Identification and Control Purposes." Processes 8, no. 6 (2020): 682. http://dx.doi.org/10.3390/pr8060682.
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This paper proposes a theoretical framework for generalization of the well established first order plus dead time (FOPDT) model for linear systems. The FOPDT model has been broadly used in practice to capture essential dynamic response of real life processes for the purpose of control design systems. Recently, the model has been revisited towards a generalization of its orders, i.e., non-integer Laplace order and fractional order delay. This paper investigates the stability margins as they vary with each generalization step. The relevance of this generalization has great implications in both the identification of dynamic processes as well as in the controller parameter design of dynamic feedback closed loops. The discussion section addresses in detail each of this aspect and points the reader towards the potential unlocked by this contribution.
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Muresan, Cristina I., Isabela R. Birs, and Eva H. Dulf. "Event-Based Implementation of Fractional Order IMC Controllers for Simple FOPDT Processes." Mathematics 8, no. 8 (2020): 1378. http://dx.doi.org/10.3390/math8081378.
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Fractional order calculus has been used to generalize various types of controllers, including internal model controllers (IMC). The focus of this manuscript is towards fractional order IMCs for first order plus dead-time (FOPDT) processes, including delay and lag dominant ones. The design is novel at it is based on a new approximation approach, the non-rational transfer function method. This allows for a more accurate approximation of the process dead-time and ensures an improved closed loop response. The main problem with fractional order controllers is concerned with their implementation as higher order transfer functions. In cases where central processing unit CPU, bandwidth allocation, and energy usage are limited, resources need to be efficiently managed. This can be achieved using an event-based implementation. The novelty of this paper resides in such an event-based algorithm for fractional order IMC (FO-IMC) controllers. Numerical results are provided for lag and delay dominant FOPDT processes. For comparison purposes, an integer order PI controller, tuned according to the same performance specifications as the FO-IMC, is also implemented as an event-based control strategy. The numerical results show that the proposed event-based implementation for the FO-IMC controller is suitable and provides for a smaller computational effort, thus being more suitable in various industrial applications.
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Tan, Gong Quan, Yong Hui Chen, and Shu Chuan Gan. "PID Controller Design Based on Modified IMC and Optimal Robust Performance Based on Applied Mechanics." Advanced Materials Research 485 (February 2012): 114–18. http://dx.doi.org/10.4028/www.scientific.net/amr.485.114.
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In this work, PID design with acceptable performance and robustness of closed-loop system was introduced. With the normalized time constant of internal model control (IMC) replaced by a damping ratio and a new time constant, a modified IMC was proposed and could be equivalent to a proportional integral derivative (PID) control. Since the control systems always have a dilemma between performance and robustness, the robust performance index was created with the integral of absolute error (IAE) weighted by the maximum sensitivity (Ms) with an exponential factor and the PID parameters were optimized through it. As an example, an empirical weighted factor 1.5 was selected to obtain the self-tuning PID formula for first-order plus delay time (FOPDT) processes. Simulation results show that the proposed PID control achieves good closed-loop performance and robustness.
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Rao, A. Seshagiri, V. S. R. Rao, and M. Chidambaram. "Simple Analytical Design of Modified Smith Predictor with Improved Performance for Unstable First-Order Plus Time Delay (FOPTD) Processes." Industrial & Engineering Chemistry Research 46, no. 13 (2007): 4561–71. http://dx.doi.org/10.1021/ie061308n.
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Lee, Jietae, Wonhui Cho, and Thomas F. Edgar. "Control system design based on a nonlinear first-order plus time delay model." Journal of Process Control 7, no. 1 (1997): 65–73. http://dx.doi.org/10.1016/s0959-1524(96)00014-5.
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Zhang, Quan Ling. "Multivariable Predictive Functional Control for the First-Order Plus Time-Delay System." Advanced Materials Research 282-283 (July 2011): 32–37. http://dx.doi.org/10.4028/www.scientific.net/amr.282-283.32.
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A multivariable predictive functional control (M-PFC) algorithm based on a two-inputs/two-outputs system with the transfer function model is presented in this paper. A simple and explicit solution of manipulated variables of the control system can be obtained by optimizing the objective function. Simulations of the system applying M-PFC are also provided in here, showing that the presented algorithm has good performance of tracking set-point without steady-state error, disturbance rejection and robustness. Finally, the application of temperature control for the methylamine synthesizing tower is addressed, demonstrating the effectiveness of the proposed PFC algorithm.
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Ibn Taarit, Kaouther, and Mekki Ksouri. "Algebraic identification of a stable first‐order plus time delay model from step response." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 31, no. 6 (2012): 1558–74. http://dx.doi.org/10.1108/03321641211266994.
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Fedele, Giuseppe. "A new method to estimate a first-order plus time delay model from step response." Journal of the Franklin Institute 346, no. 1 (2009): 1–9. http://dx.doi.org/10.1016/j.jfranklin.2008.05.004.
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Gharab, Saddam, Vicente Feliu-Batlle, and Raul Rivas-Perez. "A Fractional-Order Partially Non-Linear Model of a Laboratory Prototype of Hydraulic Canal System." Entropy 21, no. 3 (2019): 309. http://dx.doi.org/10.3390/e21030309.
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This article addresses the identification of the nonlinear dynamics of the main pool of a laboratory hydraulic canal installed in the University of Castilla La Mancha. A new dynamic model has been developed by taking into account the measurement errors caused by the different parts of our experimental setup: (a) the nonlinearity associated to the input signal, which is caused by the movements of the upstream gate, is avoided by using a nonlinear equivalent upstream gate model, (b) the nonlinearity associated to the output signal, caused by the sensor’s resolution, is avoided by using a quantization model in the identification process, and (c) the nonlinear behaviour of the canal, which is related to the working flow regime, is taken into account considering two completely different models in function of the operating regime: the free and the submerged flows. The proposed technique of identification is based on the time-domain data. An input pseudo-random binary signal (PRBS) is designed depending on the parameters of an initially estimated linear model that was obtained by using a fundamental technique of identification. Fractional and integer order plus time delay models are used to approximate the responses of the main pool of the canal in its different flow regimes. An accurate model has been obtained, which is composed of two submodels: a first order plus time delay submodel that accurately describes the dynamics of the free flow and a fractional-order plus time delay submodel that properly describes the dynamics of the submerged flow.
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Burgess, Don E., Jon C. Hundley, Sheng-Gang Li, David C. Randall, and David R. Brown. "First-order differential-delay equation for the baroreflex predicts the 0.4-Hz blood pressure rhythm in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 273, no. 6 (1997): R1878—R1884. http://dx.doi.org/10.1152/ajpregu.1997.273.6.r1878.
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We have described a 0.4-Hz rhythm in renal sympathetic nerve activity (SNA) that is tightly coupled to 0.4-Hz oscillations in blood pressure in the unanesthetized rat. In previous work, the relationship between SNA and fluctuations in mean arterial blood pressure (MAP) was described by a set of two first-order differential equations. We have now modified our earlier model to test the feasibility that the 0.4-Hz rhythm can be explained by the baroreflex without requiring a neural oscillator. In this baroreflex model, a linear feedback term replaces the sympathetic drive to the cardiovascular system. The time delay in the feedback loop is set equal to the time delay on the efferent side, ∼0.5 s (as determined in the initial model), plus a time delay of 0.2 s on the afferent side for a total time delay of ∼0.7 s. A stability analysis of this new model yields feedback resonant frequencies close to 0.4 Hz. Because of the time delay in the feedback loop, the proportional gain may not exceed a value on the order of 10 to maintain stability. The addition of a derivative feedback term increases the system’s stability for a positive range of derivative gains. We conclude that the known physiological time delay for the sympathetic portion of the baroreflex can account for the observed 0.4-Hz rhythm in rat MAP and that the sensitivity of the baroreceptors to the rate of change in blood pressure, as well as average blood pressure, would enhance the natural stability of the baroreflex.
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P.R., Hemavathy, Mohamed Shuaib Y, and S. K. Lakshmanaprabu. "Internal model controller based PID with fractional filter design for a nonlinear process." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 1 (2020): 243. http://dx.doi.org/10.11591/ijece.v10i1.pp243-254.
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In this paper, an Internal model Controller (IMC) based PID with fractional filter for a first order plus time delay process is proposed. The structure of the controller has two parts, one is integer PID controller part cascaded with fractional filter. The proposed controller has two tuning factors λ, filter time constant and a, fractional order of the filter. In this work, the two factors are decided in order to obtain low Integral Time Absolute Error (ITAE). The effectiveness of the proposed controller is studied by considering a non linear (hopper tank) process. The experimental set up is fabricated in the laboratory and then data driven model is developed from the experimental data. The non linear process model is linearised using piecewise linearization and two linear regions are obtained. At each operating point, linear first order plus dead time model is obtained and the controller is designed for the same. To show the practical applicability, the proposed controller is implemented for the proposed experimental laboratory prototype.
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YADAV, RISHI PAL, P. V. VARDE, AMIT CHAUHAN, and PRAVIN FATNANI. "RELAY FEEDBACK-BASED CRITICAL PARAMETER ESTIMATION FOR FIRST ORDER PLUS DEAD TIME TYPE PLANT IN NETWORKED CONTROL SYSTEM CONFIGURATION." International Journal of Modeling, Simulation, and Scientific Computing 02, no. 03 (2011): 375–91. http://dx.doi.org/10.1142/s1793962311000542.
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Most control strategies for networked control systems (NCS) assume that system model is known "a priori" which is, however, impractical in many industrial applications. To obtain the model of First Order Plus Dead Time type plant for networked control, this paper concentrates on model identification under the networked control environment. Ideal-relay feedback-based networked identification scheme is proposed here along with the new packet-based real-time queuing protocol to identify the plant's critical parameters, which takes into account the effect of nondeterministic factors such as network-induced delay, data packet disordering, and limited data packet loss between the sensor and controller as well as the controller and the actuator. Experimental results show that the proposed networked identification scheme can effectively overcome the impact of various network-induced nondeterministic factors for ideal-relay-based model identification in NCS.
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Liu, J. Z., J. K. Pieper, and B. W. Surgenor. "Deadtime Compensation and Zero Frequency Decoupling of a Thermal Hydraulic Process." Journal of Dynamic Systems, Measurement, and Control 114, no. 3 (1992): 527–31. http://dx.doi.org/10.1115/1.2897382.
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This brief details the design and experimental implementation of a practical multivariable controller applied to a thermal hydraulic process. Features of the design include a first-order plus deadtime process model, zero frequency decoupling, and multivariable deadtime compensation. The deadtime compensator allowed higher loop gains and consequently improved overall performance. Practical first order prediction based on an estimated delay and process time constant achieved the deadtime compensation. The high gain controller effectively handled both setpoint changes and disturbance rejection. An intelligent choice of estimation schemes yielded a simple but accurate model.
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Nasir, A. W., I. Kasireddy, and A. K. Singh. "Real Time Speed Control of a DC Motor Based on its Integer and Non-Integer Models Using PWM Signal." Engineering, Technology & Applied Science Research 7, no. 5 (2017): 1974–79. http://dx.doi.org/10.48084/etasr.1292.
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This paper exploits the advantage of non-integer order modeling of a process over integer order, in those cases where the process model is required for control purpose. The present case deals with speed control of a DC motor. Based on the real time open loop response, DC motor is being modeled as integer and non-integer order first order plus delay system. Both these models are then separately used for determining two sets of Proportional-Integral-Derivative (PID) controller parameters through Ziegler Nichols (ZN) closed loop tuning method. In addition to this, a model based control technique i.e. Internal Model Control (IMC) is also implemented using both integer and non-integer model respectively. For carrying out the real time speed control of DC motor, LabVIEW platform has been used. After going through the results, it is observed that the controller performance considerably improves, if non-integer order model is used for controller design rather than integer order model.
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Mabu Sarif, B., D. V. Ashok Kumar, and M. Venu Gopala Rao. "Disturbance rejection using IMC tuned PID controller with improved filter." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 3 (2020): 1261. http://dx.doi.org/10.11591/ijeecs.v20.i3.pp1261-1270.
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<p>IMC-PID controllers supply exceptional set point tracking but slow<br />disturbance refutation, because of introduction of slow process pole<br />introduced by the conventional filter. Disturbance rejection is important in<br />many industrial applications over set point tracking. An enhanced IMC filter<br />cascaded with PID controller with Internal Model Control Tuning System<br />(IMC-PID) is presented right now for efficient disruption rejection and<br />reliable first order process operation with time delay (FOPTD). The optional<br />filter does away with the sluggish dominant pole. The present learning shows<br />that the recommended IMC filter provide excellent trouble rejection<br />irrespective of where the trouble enters the procedure and provide high-<br />quality robustness to duplicate deviation in surroundings of accepting in<br />difference with other method cited in the text. Reenactment study was led to<br />show the feasibility of the suggested approach on processes with different 0/r ratios by measuring the controller parameters while retaining the same<br />robustness as regards maximal sensitivity. His efficiency of the closed loops<br />was assessed utilizing integral error parameters. Viz. ISE, ITAE, IAE. The<br />recommended filter provides excellent response pro lag dominant processes.</p>
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Zhao, Min, and Yan Xia Jiang. "Off-Line Robust MPC Algorithm for VAV Air-Conditioning Systems." Advanced Materials Research 846-847 (November 2013): 293–96. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.293.
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The efficient temperature control of variable air volume (VAV) air-conditioning system can greatly reduce the energy consumption. In order to due with system constraints and uncertainties, and guarantee the closed-loop stability, an off-line min-max robust model predictive control algorithm is presented for the temperature control of a VAV system. As the first-order-plus-time-delay model of system is described by a polyhedral described uncertain model, the off-line ellipsoidal invariant set based robust MPC algorithm is employed for the controller design. Simulation results show efficiency of the proposed control algorithm implemented in the temperature control of a VAV system, which can enhance robustness, and satisfy the constraints.
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Tang, Wei, Xu Zhong Niu, and Wen Juan Shan. "Application of IMC-PID in the Hydraulic Headbox Total Pressure Control." Advanced Materials Research 462 (February 2012): 789–95. http://dx.doi.org/10.4028/www.scientific.net/amr.462.789.
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It is very difficult to obtain perfect performance to apply the conventional PID (Proportional-Integral-Derivative) controller, because hydraulic headbox needs high precision total pressure control. Transfer function of total pressure control system was identified by using the direct identification method which is based on the least square method for the first-order plus delay time model. Then combined with IMC (Internal-Model-control) –PID method, an IMC-PID controller was designed, which is simple and only needed to adjust one parameter-the time constant of low pass filter. Acceptable performance can also be obtained by tuning time constant of the low pass filter when the model doesn't match with the real process. The algorithm was applied to total pressure control system of hydraulic headbox. Simulation and practical application show that, IMC-PID is of strong robustness and good dynamic characteristics. Finally, the control system is implemented by S7-300 PLC.
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Donner, Kristian, and Simo Hemilä. "Modelling the spatio-temporal modulation response of ganglion cells with difference-of-Gaussians receptive fields: Relation to photoreceptor response kinetics." Visual Neuroscience 13, no. 1 (1996): 173–86. http://dx.doi.org/10.1017/s0952523800007215.
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AbstractDifference-of-Gaussians (DOG) models for the receptive fields of retinal ganglion cells accurately predict linear responses to both periodic stimuli (typically moving sinusoidal gratings) and aperiodic stimuli (typically circular fields presented as square-wave pulses). While the relation of spatial organization to retinal anatomy has received considerable attention, temporal characteristics have been only loosely connected to retinal physiology. Here we integrate realistic photoreceptor response waveforms into the DOG model to clarify how far a single set of physiological parameters predict temporal aspects of linear responses to both periodic and aperiodic stimuli. Traditional filter-cascade models provide a useful first-order approximation of the single-photon response in photoreceptors. The absolute time scale of these, plus a time for retinal transmission, here construed as a fixed delay, are obtained from flash/step data. Using these values, we find that the DOG model predicts the main features of both the amplitude and phase response of linear cat ganglion cells to sinusoidal flicker. Where the simplest model formulation fails, it serves to reveal additional mechanisms. Unforeseen facts are the attenuation of low temporal frequencies even in pure center-type responses, and the phase advance of the response relative to the stimulus at low frequencies. Neither can be explained by any experimentally documented cone response waveform, but both would be explained by signal differentiation, e.g. in the retinal transmission pathway, as demonstrated at least in turtle retina.
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Abdel-Jabbar, Nabil, Wasim Ahmed, and Zarook Shareefdeen. "System Identification and Control of a Biotrickling Filter." Chemical Product and Process Modeling 10, no. 1 (2015): 39–53. http://dx.doi.org/10.1515/cppm-2014-0025.
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Abstract This paper studies empirical modeling and control of a biotrickling filter (BTF) used for air pollution control. Step response transfer function (TF) with first-order-plus-time-delay model and steady-state artificial neural network (NN) model were developed for BTF based on input–output (I/O) data obtained from simulation of a rigorous model. These simple models offer fast predictions compared to the rigorous model and render control implementation for BTF feasible. Gas velocity and inlet concentration of hydrogen sulfide (H2S) (target pollutant) were considered as the main process inputs while outlet concentration of H2S was selected as the BTF performance variable (output). The TF and NN models fitted well with the I/O data and the resulting regression coefficient values were above 0.97. Different simulations with the fitted NN model were performed and compared with the rigorous model data at steady state. The NN model perfectly captured the steady-state behavior of the BTF process. Two control strategies were implemented, namely proportional–integral/feedback control and model predictive control, also known as receding-horizon control. The controllers were based on the fitted TF model representation of BTF under study. For the control structure, gas velocity, inlet concentration, and outlet concentration were selected as manipulated, disturbance and controlled variables, respectively. Through set-point and disturbance change tests, it was observed that the model predictive controller offered superior set-point tracking capabilities while the feedback controller showed better control in dealing with disturbances. However, both controllers provided adequate control in general.
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Huang, Gongsheng, and Tin-Tai Chow. "Uncertainty shift in robust predictive control design for application in CAV air-conditioning systems." Building Services Engineering Research and Technology 32, no. 4 (2011): 329–43. http://dx.doi.org/10.1177/0143624411399686.
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Constant-air-volume (CAV) air-conditioning systems consist mainly of two local processes: an air-handling process and a room temperature process. A robust model predictive control (RMPC) strategy was developed for CAV air-conditioning systems, which adopted two uncertain first-order plus time-delay models to describe the dynamics of the local processes and used a linear matrix inequality (LMI)-based optimisation technique to optimise the control law. This paper develops a new control design, which reformulates the prediction models by shifting the uncertainties of the first model into the second one, and then uses the reformulated prediction models in the RMPC strategy. This paper will show that compared with the original design, the new control design can enhance the feasibility of the optimisation of control law, reduce the computational burden of the optimisation and also remove the requirement of a sensor for supply air temperature in the original design. Practical applications: The new design method is a further development of a RMPC strategy presented in Xu et al.13 It inherits the benefits of the original control design for practical application, i.e. uncertainties and constraints can be dealt with simultaneously in the design and the robustness of the controlled system can be enhanced. The new design improves the optimisation feasibility, reduces the computational complexity and does not need to measure the supply air temperature. When the new design is adopted to replace the traditional PI control, there is no necessity to change the existent input structure of the PI control. Hence, the new design can be realised in practice easier than the original design.
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Divi, Srinivasarao, Shantanu Das, G. Uday Bhaskar Babu, and S. H. Sonawane. "Fractional Order PID Controller Design for Supply Manifold Pressure Control of Proton Exchange Membrane Fuel Cell." Chemical Product and Process Modeling 14, no. 3 (2019). http://dx.doi.org/10.1515/cppm-2018-0053.
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Abstract In this work, fractional order PIλDµ (FOPID) controller designed to enhance the dynamic performance of the Proton Exchange Membrane (PEM) fuel cell. The control objective is to regulate the supply manifold pressure on cathode side to maintain oxygen excess ratio of the PEM fuel cell. The higher order PEM fuel cell model is approximated to First order plus time delay (FOPTD) model for controller design and analysis. The proposed FOPID controller is designed based on minimization of Integral Absolute Error (IAE) with pre specified maximum sensitivity (Ms) as a constraint. Uncertainty and measurement noise analysis is carried out to verify the robustness of the designed controller. The simulation results of proposed FOPID controller is compared with other designing methods. Based on minimization of IAE value, the SP 1.4 FOPID controller produces IAE value of 0.255 where as AMIGO 1.4 tuning method and ZN based FOPID tuning methods produces 0.263 and 3.817 respectively for perfect case. Based on maximum sensitivity Ms is 1.4, the SP 1.4 FOPID controller produces Ms of 1.4 where as AMIGO 1.4 PID and ZN based FOPID tuning methods produces Ms of 1.5 and 1.25 respectively for perfect case, which indicates that the proposed SP 1.4 FOPID controller is robust. The proposed SP 1.4 FOPID provides better values (rise time of 0.331 sec, settling time of 0.692 sec and percentage of peak overshoot of 0.797 for perfect case) when compared with other methods. From simulation results, for the control of supply manifold pressure of PEM fuel cell, the proposed fractional-order PID controllers improves the closed loop performance in terms of rise time, settling time and percentage of peak overshoot when compared to the integer-order PID controllers.
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"Design and Simulation of PID Controller for PH Neutralization Process." International Journal of Innovative Technology and Exploring Engineering 9, no. 3 (2020): 2740–43. http://dx.doi.org/10.35940/ijitee.c9236.019320.
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PH control system plays an important role in a wide range of industrial applications particularly in wastewater treatment management. Untreated wastewater generally contains high level of organic materials, numerous pathogenic microorganisms which raised concern in environmental and health hazards. The high non-linearity and time varying in pH neutralization process and the uncertainty of the plant dynamics are the key challenges of the pH control systems. There are many sophisticated PID tuning method, however conventional tuning procedure remains effectives in industries. The overall control scheme involves controls of flow rates of acid and base solutions. Ziegler Nichols method tuning has been developed for first order and second order system, in which, also applicable for pH neutralization control model. This paper elaborates the performance of transient response for pH neutralization process by using empirical techniques through the simulation software along with Proportional-Integral-Derivative (PID) for controlling purpose. A result of comparison between Ziegler-Nichols versus First Order plus Time Delay (FOPTD) of pH control system design for PID controller is seeing in a graph.
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Nath, Ujjwal Manikya, Chanchal Dey, and Rajani K. Mudi. "Designing of IMC-PID Controller for Higher-order Process Based on Model Reduction Method and Fractional Coefficient Filter with Real-time Verification." Chemical Product and Process Modeling 15, no. 3 (2019). http://dx.doi.org/10.1515/cppm-2019-0089.
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AbstractAn improved model reduction scheme is proposed here for higher-order processes and subsequently an enhanced IMC-PID controller is designed based on the obtained reduced model. In the proposed scheme, higher-order processes are estimated as first-order-plus-dead-time (FOPDT) model. Designed IMC controller includes a filter having two separate time constants with fractional order coefficients. Efficacy of the proposed model reduction scheme is verified in terms of closed loop performance evaluation for higher-order minimum and non-minimum phase process models in comparison with improved SIMC (iSIMC) controller (Grimholt. Optimal PI and PID control of first-order plus delay processes and evaluation of the original and improved SIMC rules. J Process Control. 2018;70:36–46). Overall performance enhancement for the proposed method is demonstrated through simulation study as well as real-time experimentation on a level control loop.
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Chen, YangQuan, Tripti Bhaskaran, and Dingyü Xue. "Practical Tuning Rule Development for Fractional Order Proportional and Integral Controllers." Journal of Computational and Nonlinear Dynamics 3, no. 2 (2008). http://dx.doi.org/10.1115/1.2833934.
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This paper presents a new practical tuning method for fractional order proportional and integral (FO-PI) controller. The plant to be controlled is mainly first order plus delay time (FOPDT). The tuning is optimum in the sense that the load disturbance rejection is optimized yet with a constraint on the maximum or peak sensitivity. We generalized Ms constrained integral (MIGO) based controller tuning method to handle the FO-PI case, called F-MIGO, given the fractional order α. The F-MIGO method is then used to develop tuning rules for the FOPDT class of dynamic systems. The final developed tuning rules only apply the relative dead time τ of the FOPDT model to determine the best fractional order α and at the same time to determine the best FO-PI gains. Extensive simulation results are included to illustrate the simple yet practical nature of the developed new tuning rules. The tuning rule development procedure for FO-PI is not only valid for FOPDT but also applicable for other general class of plants.
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Ranganayakulu, R., G. Uday Bhaskar Babu, and A. Seshagiri Rao. "Analytical Design of Enhanced Fractional Filter PID Controller for Improved Disturbance Rejection of Second Order Plus Time Delay Processes." Chemical Product and Process Modeling 14, no. 1 (2018). http://dx.doi.org/10.1515/cppm-2018-0012.
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Abstract In this article, a modified fractional internal model control (IMC) filter structure is proposed to design a fractional filter Proportional-Integral-Derivative (FFPID) controller for improved disturbance rejection of second order plus time delay (SOPTD) processes. The proposed method aims at improving the disturbance rejection of slow chemical processes as the tuning rules for such processes are limited. The present design also considers the higher order approximation for time delay as it gives improved response for higher order processes. There is an additional tuning parameter in the proposed IMC filter apart from the conventional IMC filter time constant, which is tuned according to the derived formula. The additional adjustable parameter achieves the disturbance rejection and the closed loop stability. The simulation results have been performed for the same degree of robustness (maximum sensitivity, Ms) for a fair comparison. The results show an improved disturbance rejection for lag dominant and delay significant SOPTD processes with the proposed controllers designed using higher order Pade’s approximation of time delay than the proposed method using first order approximation and the conventional method. The closed loop robust performance is observed for perturbations in the process parameters and the performance is also observed for noise in the measurement. The robust stability analysis is carried out using sensitivity functions. In addition, the Ms range is also identified over which the system gives robust performance for the controllers designed using higher order pade’s approximation of time delay compared to conventional method.
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Alyoussef, Fadi, and Ibrahim Kaya. "Tuning proportional-integral controllers based on new analytical methods for finding centroid of stability locus for stable/unstable first-order plus dead-time processes." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, September 25, 2021, 095965182110480. http://dx.doi.org/10.1177/09596518211048028.
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The simplicity of the proportional-integral controller makes it very popular in many practical engineering applications. In the literature, several approaches have been introduced for tuning proportional-integral controllers by calculating the centroid of the stability region. However, all those approaches depend on graphical plottings which are time-consuming. Also, the design procedure has to be redone as the transfer function changes. Here, two new analytical methods are proposed to obtain the centroid of the stability region for the proportional-integral controllers to control a time delay process which can be modeled by a stable or unstable first-order plus dead-time model. The methods introduced eliminate the compulsory procedure of plotting the stability region. The efficiency of the suggested methods has been studied by conducting a robustness analysis and studying several simulation examples.
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Ivanov, A. P., V. G. Shavrov, and V. I. Shcheglov. "The non-stationary delay of establishment nonlinear vibrations in the system of two connected oscillators. Part 4. Circular interaction." Journal of Radio Electronics, April 2021. http://dx.doi.org/10.30898/1684-1719.2021.4.7.
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This work is the continuation of investigation of non-stationary delay of establishment nonlinear vibrations in the system of two connected oscillators. The physical foundation of this task is the excitation of power hypersound in ferrite plate having magnetoelastic properties and also excitation of intensive electromagnetic vibrations in ferrite disc placed in electro-dynamic resonator. It is found that under certain conditions the vibrations in these systems take character of non-stationary large-amplitude chaos which excites with large delay after the system is switched. The foundation of this work is received in the first part of this work the enough general system of two connected differential second order equations having nonlinearity as the power row to third order. As a result of elimination of secondary parameters from fundamental system it was selected the reduced system – «initial core» which preserves the properties of non-stationary delay and chaos. It is found the circular character of reduced system. In this character the determined by first equation displacement of first oscillator influences to the displacement of second oscillator through the linear connection of second equation. The received in this case displacement of second oscillator again return to the first equation through the item of nonlinear connection of first equation. In this case the whole connection of equations between ones forms the «ring», which is closed by itself. The first oscillator in this ring has the «mediator» – the second oscillator which plays the subordinate role. In the scheme of break ring the successive influence of oscillators one to other is investigated. It is shown that the influence of sinusoidal signal with constant amplitude to second oscillator leads to the excitation of its vibrations which has the beating character. The influence of these beatings to first oscillator leads to the large delay of excitation chaotic vibrations. The possibility of existence of ring in classic system of Lorents which admit chaotic vibrations. By the replacement of variables it is execute the transformation of Lorents system having three equations of first order to equivalent system having two equations. In this system the first equation has second order and second equation has first order. For this system it is established the circular character. In this case the first order equation for second oscillator is the «mediator» for second order equation for first oscillator. It is shown that the classic Lorents system which is described as a system of two equations has circular character which is the similar to the circular character for two oscillators. In Lorents system the development of large-amplitude chaos is accompanied by time-delay which has form of interval of regularity which is the similar as time-delay in system for two oscillators. The circular character of relax system for two oscillators is investigated. It is proposed the algorithm of step by step calculation hawing two stages character. The first stage is the passage of first half of whole ring which is determined by first equation. The second stage is the passage of second half of whole ring which is determined by second equation. It is established the possibility of presentation of system from two equations in the form when each equation contains selected from corresponding equation the own variable quantity which is equated for the remaining part of initial equation. It is established the circular character of this presentation. It is shown that the substitution the second variable form second equation to the first equation leads to the equation which contain only first variable. The excitation which is found by this substitution is named as «ring excitation» and its solution is named by «ring function». It is established that by the reason of large complexity of ring equation the unique method of its solution is step by step method. In this case the meaning of the variable on present step is determined by the function which contains the same variable which is determined on previous step. It is attended the analogy of this solution with the calculation of discrete single size reflection. On the example of classic logistical reflection it is calculated the development of vibrations by steps for some meanings of parameters which spread the regular dissipative, regular stationary and chaotic regimes. It is established that the delay by steps for logistical reflection is absent. It is established the possibility of ring equation solution as ring function using the same step by step method which is used for the calculation of reflections. It is proposed two variety of ring functions – first and second kind which in the quality of discrete varying variable uses the time. The left part of vibration function of both kinds is the variety – the displacement of first oscillator on the present step. The right part contains the trigonometric function (sine or cosine) which argument is the product of generalized frequency on the time which correspond to the previous step. For the ring function of first kind the generalized function is proportional to the displacement of oscillator plus unit. For the ring function of second kind the generalized frequency is proportional to the displacement of oscillator plus value of frequency which is determined by previous step. It is investigated the development of vibrations on time which is described by ring functions of first and second kinds. It ir proposed the algorithm of calculation which is similar to algorithm which is used for the reflections. It is shown that the vibrations in time are developed in two stages. For the ring function of first kind during the first stage the vibrations are the regular sine and during the second stage on the regular sine is deposited the chaotic vibrations having more lesser period. For the ring function of second kind during the first stage the vibrations are absent which is its delay and during the second stage the large-amplitude chaos is developed. As a result of performed investigation it is shown that the ring functions of second kind provide the convenient imitation of delay and development of the large-amplitude chaos in the system of two oscillators. For the ring function of second kind it is investigated the beginning of development of delay the large-amplitude vibrations and its end and transition to the large-amplitude chaos. It is proposed the model which is consist of the aspiration of function argument during the time to decrease to value π/2 and the increasing of displacement which try to increase of this argument. The exit from delay and beginning of the large-amplitude vibrations is passed through the breach of this balance which is determined by the excitation of vibrations having triangular form. It is proposed some comments about possible development of this work. As an important task it is mentioned the construction of model idea about duration of delay time. This question may be expanded not only the system of two oscillators and also on the ring functions and supplemented the investigation of interval of regularity in Lorents system. It is mentioned the importance of investigation of the role of nonlinear connection having high orders. This investigation may be applied to more wide round of phenomena.
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A. A. Emhemed, Abdulrahman, Rosbi Mamat, and Ahmad ‘Athif Mohd Faudzi. "NON-PARAMETRIC IDENTIFICATION TECHNIQUES FOR INTELLIGENT PNEUMATIC ACTUATOR." Jurnal Teknologi 77, no. 20 (2015). http://dx.doi.org/10.11113/jt.v77.6560.
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The aim of this paper is to present experimental, empirical and analytic identification techniques, known as non-parametric techniques. Poor dynamics and high nonlinearities are parts of the difficulties in the control of pneumatic actuator functions, which make the identification technique very challenging. Firstly, the step response experimental data is collected to obtain real-time force model of the intelligent pneumatic actuator (IPA). The IPA plant and Personal Computer (PC) communicate through Data Acquisition (DAQ) card over MATLAB software. The second method is approximating the process by curve reaction of a first-order plus delay process, and the third method uses the equivalent n order process with PTn model parameters. The obtained results have been compared with the previous study, achieved based on force system identification of IPA obtained by the (Auto-Regressive model with eXogenous) ARX model. The models developed using non-parameters identification techniques have good responses and their responses are close to the model identified using the ARX system identification model. The controller approved the success of the identification technique with good performance. This means the Non-Parametric techniques are strongly recommended, suitable, and feasible to use to analyze and design the force controller of IPA system. The techniques are thus very suitable to identify the real IPA plant and achieve widespread industrial acceptance.
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Tsai, Alex, David Tucker, and Craig Groves. "Improved Controller Performance of Selected Hybrid SOFC-GT Plant Signals Based on Practical Control Schemes." Journal of Engineering for Gas Turbines and Power 133, no. 7 (2011). http://dx.doi.org/10.1115/1.4002253.
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This paper compares and demonstrates the efficacy of implementing two practical single input single output multiloop control schemes on the dynamic performance of selected signals of a solid oxide fuel cell gas turbine (SOFC-GT) hybrid simulation facility. The hybrid plant located at the U.S. Department of Energy National Energy Technology Laboratory in Morgantown, WV is capable of simulating the interaction between a 350 kW solid oxide fuel cell and a 120 kW gas turbine using a hardware in the loop configuration. Previous studies have shown that the thermal management of coal based SOFC-GT hybrid systems is accomplished by the careful control of the cathode air stream within the fuel cell (FC). Decoupled centralized and dynamic decentralized control schemes are tested for one critical airflow bypass loop to regulate cathode FC airflow and modulation of turbine electric load to maintain synchronous turbine speed during system transients. Improvements to the studied multivariate architectures include: feed-forward control for disturbance rejection, antiwindup compensation for actuator saturation, gain scheduling for adaptive operation, bumpless transfer for manual to auto switching, and adequate filter design for the inclusion of derivative action. Controller gain tuning is accomplished by Skogestad’s internal model control tuning rules derived from empirical first order plus delay time transfer function models of the hybrid facility. Avoidance of strong input-output coupling interactions is achieved via relative gain array, Niederlinski index, and decomposed relative interaction analysis, following recent methodologies in proportional integral derivative control theory for multivariable processes.