Records with Subject: Process Control
Showing records 76 to 100 of 308. [First] Page: 1 2 3 4 5 6 7 8 Last
Optimal Speed Control for a Semi-Autogenous Mill Based on Discrete Element Method
Xiaoli Wang, Jie Yi, Ziyu Zhou, Chunhua Yang
April 14, 2020 (v1)
Keywords: discrete element method (DEM), optimal speed, SAG mill, sliding mode control
The rotation speed of a mill is an important factor related to its operation and grinding efficiency. Analysis and regulation of the optimal speed under different working conditions can effectively reduce energy loss, improve productivity, and extend the service life of the equipment. However, the relationship between the optimal speed and different operating parameters has not received much attention. In this study, the relationship between the optimal speed and particle size and number was investigated using discrete element method (DEM). An improved exponential approaching law sliding mode control method is proposed to track the optimal speed of the mill. Firstly, a simulation was carried out to investigate the relationship between the optimal speed and different operating parameters under cross-over testing. The model of the relationships between the optimal rotation speed and the size and number of particles was established based on the response surface method. An improved sliding... [more]
On Parameter Stability Region of LADRC for Time-Delay Analysis with a Coupled Tank Application
Dazi Li, Xun Chen, Jianqing Zhang, Qibing Jin
April 14, 2020 (v1)
Keywords: dual-locus diagram, GA, LADRC, parameter stability region, PLC
The control of time-delay systems is a hot research topic. Ever since the theory of linear active disturbance rejection control (LADRC) was put forward, considerable progress has been made. LADRC shows a good control effect on the control of time-delay systems. The problem about the parameter stability region of LADRC controllers has been seldom discussed, which is very important for practical application. In this study, the dual-locus diagram method, which is used to solve the upper limit of the LADRC controller bandwidth, is studied for both first-order time-delay systems and second-order time-delay systems. The characteristic equation roots distribution is firstly transformed into the problem of finding the frequency of the dual-locus diagram intersection point. To solve the problem for second-order time-delay system LADRC controllers, which is a dual 10-order nonlinear equation, a transformation has been made through Euler’s formula and genetic algorithm (GA) has been adopted to se... [more]
Comparing Composition Control Structures for Kaibel Distillation Columns
Yang Yuan, Kejin Huang, Haisheng Chen, Xing Qian, Lijing Zang, Liang Zhang, Shaofeng Wang
April 14, 2020 (v1)
Keywords: composition control, DWDC, Kaibel distillation column, PID, process control
Although Kaibel distillation columns are superior to conventional distillation sequences owing to smaller equipment investment and operation cost, they display high nonlinearity and this greatly increases the difficulty of achieving their tight control. To overcome this problem, four decentralized composition control structures, i.e., the CSR/QR, CSR/B, CSD/QR, and CSD/B structures, are proposed and compared based on the control of a Kaibel distillation column fractionating a methanol/ethanol/propanol/butanol quaternary mixture. These four composition control structures all include five composition control loops. While the four of them are employed to maintain the purity of the top, upper sidestream, lower sidestream, and bottom products, the remaining one is employed to minimize the energy consumption of the Kaibel distillation column by maintaining the composition of propanol at the first stage of the prefractionator. Dynamic simulation results show the CSR/QR and CSR/B structures ca... [more]
A Control-Performance-Based Partitioning Operating Space Approach in a Heterogeneous Multiple Model
Bing Wu, Ximei Liu, Yaobin Yue
April 14, 2020 (v1)
Keywords: heterogeneous multiple model, Model Predictive Control, nonlinear system, operating space partition
An operating space partition method with control performance is proposed, where the heterogeneous multiple model is applied to a nonlinear system. Firstly, the heterogeneous multiple model is obtained from a nonlinear system at the given equilibrium points and transformed into a homogeneous multiple model with auxiliary variables. Secondly, an optimal problem where decision variables are composed of control input and boundary conditions of sub-models is formulated with the hybrid model developed from the homogeneous multiple model. The computational implementation of an optimal operating space partition algorithm is presented according to the Hamilton−Jacobi−Bellman equation and numerical method. Finally, a multiple model predictive controller is designed, and the computational implementation of the multiple model predictive controller is addressed with the auxiliary vectors. Furthermore, a continuous stirred tank reactor (CSTR) is used to confirm the effectiveness of the developed met... [more]
Analytical Tuning Method of MPC Controllers for MIMO First-Order Plus Fractional Dead Time Systems
Ning He, Yichun Jiang, Lile He
April 14, 2020 (v1)
Keywords: analytical method, Model Predictive Control, multivariable fractional dead time system, parameter tuning
An analytical model predictive control (MPC) tuning method for multivariable first-order plus fractional dead time systems is presented in this paper. First, the decoupling condition of the closed-loop system is derived, based on which the considered multivariable MPC tuning problem is simplified to a pole placement problem. Given such a simplification, an analytical tuning method guaranteeing the closed-loop stability as well as pre-specified time-domain performance is developed. Finally, simulation examples are provided to show the effectiveness of the proposed method.
The Application of a New PID Autotuning Method for the Steam/Water Loop in Large Scale Ships
Shiquan Zhao, Sheng Liu, Robain De Keyser, Clara-Mihaela Ionescu
April 14, 2020 (v1)
Keywords: multi-input and multi-output system, proportional-integral-derivative controller, steam power plant, steam/water loop
In large scale ships, the most used controllers for the steam/water loop are still the proportional-integral-derivative (PID) controllers. However, the tuning rules for the PID parameters are based on empirical knowledge and the performance for the loops is not satisfying. In order to improve the control performance of the steam/water loop, the application of a recently developed PID autotuning method is studied. Firstly, a ‘forbidden region’ on the Nyquist plane can be obtained based on user-defined performance requirements such as robustness or gain margin and phase margin. Secondly, the dynamic of the system can be obtained with a sine test around the operation point. Finally, the PID controller’s parameters can be obtained by locating the frequency response of the controlled system at the edge of the ‘forbidden region’. To verify the effectiveness of the new PID autotuning method, comparisons are presented with other PID autotuning methods, as well as the model predictive control.... [more]
Research on Frequency Control of Islanded Microgrid with Multiple Distributed Power Sources
Yirong Liu, Xiaoli Wang, Shilin Wang
April 1, 2020 (v1)
Keywords: frequency control, islanded microgrid, microgrid, zone control
At present, some achievements have been made in the research on the energy management of microgrid operation. However, the research is mainly on the operation of grid-connected microgrid, while the research on the energy management of islanded microgrid is still relatively few. Frequency is one of the characteristics that affects the reliability and power quality of the microgrid. The essence of controlling frequency stability is to maintain source-load balance and redistribution of active power. Therefore, this paper proposes a frequency control strategy based on dynamically cutting machine to reduce load by analyzing the use priority of different distributed power supply and the division of load importance degree, and combining the influence degree of different frequency variation range on microgrid. To coordinate and control distributed power supply, energy storage device, and load in different frequency change areas, this paper proposes different control strategies. The seed strate... [more]
A Semi-Continuous PWA Model Based Optimal Control Method for Nonlinear Systems
Xinjian Zhu, Chunyue Song, Jun Zhao, Zuhua Xu
April 1, 2020 (v1)
Keywords: MPC, nonlinear system, optimal control, PWA model, semi-continuous
To alleviate the mode mismatch of multiple model methods for nonlinear systems when completely discrete dynamical equations are adopted, a semi-continuous piecewise affine (SCPWA) model based optimal control method is proposed. Firstly, a SCPWA model is constructed where modes evolve in continuous time and continuous states evolve in discrete time. Thanks to this model, a piecewise affine (PWA) system can switch at any time instant whereas mode switching only occurs at sample instants when a completely discrete PWA model is adopted, which improves the prediction accuracy of multi-models. Secondly, the switching condition is relaxed such that operating subspaces have overlaps and switching condition parameters are introduced. As a consequence, an optimal control problem with fixed mode switching sequence is established. Finally, a SCPWA model based model predictive control (MPC) policy is designed for nonlinear systems. The convergence of the MPC algorithm is proved. Compared with widel... [more]
A Practical Unified Algorithm of P-IMC Type
Vasile Cirtoaje
March 11, 2020 (v1)
Keywords: compensated process, discrete-time algorithm, online tuning, practical unified algorithm, process feedback gain, proportional-internal model control (P-IMC), settling time, step control principle, tuning gain
The paper presents a practical algorithm of the proportional-internal model control (P-IMC) type that can be applied to control a wide class of processes: Stable proportional processes, integral processes and some unstable processes. The P-IMC algorithm is a suitable combination between the P0-IMC algorithm and the P1-IMC algorithm, which are characterized by a too weak and a too strong impact of the tuning gain on the control action, respectively. The overall controller has five parameters: A tuning parameter K, three model parameters (steady-state gain, settling time, and time delay) and a process feedback gain used only for integral or unstable processes, to turn them into a compensated process (stable and of proportional type). For a step setpoint, the initial value of the compensated process input is approximately K times its final value. Furthermore, for K = 1 , the compensated process input is close to a step shape (step control principle). These properties enable a human... [more]
Designing Hydrogen and Oxygen Flow Rate Control on a Solid Oxide Fuel Cell Simulator Using the Fuzzy Logic Control Method
Darjat, Sulistyo, Aris Triwiyatno, Sudjadi, Andra Kurniahadi
March 11, 2020 (v1)
Keywords: flow, pressure, simulator, SOFC, voltage
A solid oxide fuel cell (SOFC) is an electrochemical cell that converts chemical energy into electrical energy by oxidizing fuel. SOFC has high efficiency and cleans oxidation residues. Research has shown the importance of SOFC control. Voltage output control is needed because of nonlinearity, slow dynamics, and proper SOFC operating restrictions. This study aims to design an SOFC simulator with output voltage control to optimize the flow rate of fuel (hydrogen) and air (oxygen). This SOFC simulator is designed based on a microcontroller model. The controller is designed using the fuzzy logic method. Tests show that the output voltage can approach the set point with an average of 340.6 volts. The pressure difference (∆Pressure) between the two gases averaged 4428 Pa, and the fuel/gas flow rate was in the range of 0.7 mol/s. The controller can correct both the output voltage of the SOFC simulator and the difference in gas pressure under 8106 Pa (0.08 atm).
Integration of Prognostics and Control of an Oil/CO2 Subsea Separation System
Lucas Ferreira Bernardino, André Felipe Ferreira de Souza, Argimiro Resende Secchi, Maurício Bezerra de Souza Jr., Anne Barros
March 11, 2020 (v1)
Keywords: equipment reliability, predictive control, remaining useful lifetime, statistic inference, subsea processing
The exploitation of reserves with a high CO2 content is challenging because of the need for its separation and the environmental impact associated with its generation. In this context, a suitable use for the generated CO2 is its reinjection into the reservoir, and subsea CO2 separation improves the efficiency of this process. The main objective of this work is to investigate the health-aware control of a subsea CO2 separation system. Previously identified linear models were used in a predictive controller with Kalman filter-based state estimation and online model update, and simulations were performed to evaluate the controller tuning. Regarding prognostics, a stochastic model of pump degradation, sensitive to its operating conditions, was proposed, and a particle filter was implemented to perform online degradation state estimation and remaining useful lifetime prediction. Finally, a health-aware controller was designed, which could extend the life of the process by four months when c... [more]
A Comparative Study on Controllers for Improving Transient Stability of DFIG Wind Turbines During Large Disturbances
Minh Quan Duong, Sonia Leva, Marco Mussetta, Kim Hung Le
February 24, 2020 (v1)
Keywords: crowbar protection, Doubly-Fed Induction Generator (DFIG), squirrel-cage induction generator (SCIG), transient stability, wind turbine
Under power system short-circuits, the Doubly-Fed Induction Generator (DFIG) Wind Turbines (WT) are required to be equipped with crowbar protections to preserve the lifetime of power electronics devices. When the crowbar is switched on, the rotor windings are short-circuited. In this case, the DFIG behaves like a squirrel-cage induction generator (SCIG) and can adsorb reactive power, which can affect the power system. A DFIG based-fault-ride through (FRT) scheme with crowbar, rotor-side and grid-side converters has recently been proposed for improving the transient stability: in particular, a hybrid cascade Fuzzy-PI-based controlling technique has been demonstrated to be able to control the Insulated Gate Bipolar Transistor (IGBT) based frequency converter in order to enhance the transient stability. The performance of this hybrid control scheme is analyzed here and compared to other techniques, under a three-phase fault condition on a single machine connected to the grid. In particula... [more]
Integrated Optimization of Speed Profiles and Power Split for a Tram with Hybrid Energy Storage Systems on a Signalized Route
Zhuang Xiao, Pengfei Sun, Qingyuan Wang, Yuqing Zhu, Xiaoyun Feng
February 24, 2020 (v1)
Keywords: hp-adaptive pseudospectral method, hybrid tram, multiple phases integrated optimization, signal control strategy
A tram with on-board hybrid energy storage systems based on batteries and supercapacitors is a new option for the urban traffic system. This configuration enables the tram to operate in both catenary zones and catenary-free zones, and the storage of regenerative braking energy for later usage. This paper presents a multiple phases integrated optimization (MPIO) method for the coordination of speed profiles and power split considering the signal control strategy. The objective is to minimize the equivalent total energy consumption of all the power sources, which includes both the energy from the traction substation and energy storage systems. The constraints contain running time, variable gradients and curves, speed limits, power balance and signal time at some intersections. The integrated optimization problem is formulated as a multiple phases model based on the characters of the signalized route. An integrated calculation framework, using hp-adaptive pseudospectral method, is propose... [more]
Optimal Control Algorithms with Adaptive Time-Mesh Refinement for Kite Power Systems
Luís Tiago Paiva, Fernando A. C. C. Fontes
February 24, 2020 (v1)
Keywords: adaptive algorithms, airborne wind energy, continuous-time systems, kite power systems, nonlinear systems, optimal control, real-time optimization, time-mesh refinement
This article addresses the problem of optimizing electrical power generation using kite power systems (KPSs). KPSs are airborne wind energy systems that aim to harvest the power of strong and steady high-altitude winds. With the aim of maximizing the total energy produced in a given time interval, we numerically solve an optimal control problem and thereby obtain trajectories and controls for kites. Efficiently solving these optimal control problems is crucial when the results are used in real-time control schemes, such as model predictive control. For this highly nonlinear problem, we derive continuous-time models—in 2D and 3D—and implement an adaptive time-mesh refinement algorithm. By solving the optimal control problem with such an adaptive refinement strategy, we generate a block-structured adapted mesh which gives results as accurate as those computed using fine mesh, yet with much less computing effort and high savings in memory and computing time.
A Voltage and Frequency Control Strategy for Stand-Alone Full Converter Wind Energy Conversion Systems
Andrés Peña Asensio, Santiago Arnaltes Gómez, Jose Luis Rodriguez-Amenedo, Manuel García Plaza, Joaquín Eloy-García Carrasco, Jaime Manuel Alonso-Martínez de las Morenas
February 24, 2020 (v1)
Keywords: frequency regulation, full converter (FC), isolated operation, permanent magnet synchronous generators (PMSGs), voltage-sourced converter, wind energy
This paper addresses the design and analysis of a voltage and frequency control (VFC) strategy for full converter (FC)-based wind energy conversion systems (WECSs) and its applicability for the supply of an isolated load. When supplying an isolated load, the role of the back-to-back converters in the FC must change with respect to a grid-connected application. Voltage and frequency are established by the FC line side converter (LSC), while the generator side converter (GSC) is responsible for maintaining constant voltage in the DC link. Thus, the roles of the converters in the WECS are inverted. Under such control strategies, the LSC will automatically supply the load power and hence, in order to maintain a stable operation of the WECS, the wind turbine (WT) power must also be controlled in a load-following strategy. The proposed VFC is fully modelled and a stability analysis is performed. Then, the operation of the WECS under the proposed VFC is simulated and tested on a real-time tes... [more]
Controllability Comparison of the Four-Product Petlyuk Dividing Wall Distillation Column Using Temperature Control Schemes
Xing Qian, Rui Liu, Kejin Huang, Haisheng Chen, Yang Yuan, Liang Zhang, Shaofeng Wang
February 12, 2020 (v1)
Keywords: dividing wall distillation column (DWDC), extended Petlyuk DWDC, simplified double temperature difference control (SDTDC), simplified temperature difference control (STDC), temperature control (TC)
An effective process intensification strategy based on dividing walls shows promising energy-saving results for distillation processes. The three-product Petlyuk dividing wall distillation columns (DWDCs) are able to save approximately 30% energy in comparison with the traditional distillation columns. Furthermore, the four-product extended Petlyuk DWDC reduces about 50% of operation costs than conventional distillation sequences. Although researchers have extensively studied control schemes for the three-product Petlyuk DWDC, relatively little work has been done on the four-product extended Petlyuk DWDC. This paper studies feasible temperature control schemes containing temperature control scheme (TC), simplified temperature difference control scheme (STDC), and simplified double temperature difference control scheme (SDTDC) for the four-product extended Petlyuk DWDC. STDC and SDTDC are introduced so as to improve the dynamic performances with simple control schemes. All three control... [more]
Non-Linear Sliding Mode Controller for Photovoltaic Panels with Maximum Power Point Tracking
Hina Gohar Ali, Ramon Vilanova Arbos, Jorge Herrera, Andrés Tobón, Julián Peláez-Restrepo
February 12, 2020 (v1)
Keywords: integer order SMC, maximum power point tracking, perturb and observe algorithm, photovoltaic panel
In this paper, nonlinear sliding mode control (SMC) techniques formulated for extracting maximum power from a solar photovoltaic (PV) system under variable environmental conditions employing the perturb and observe (P and O) maximum power point tracking (MPPT) technique are discussed. The PV system is connected with load through the boost converter. A mathematical model of the boost converter is derived first, and based on the derived model, a SMC is formulated to control the gating pulses of the boost converter switch. The closed loop system stability is verified through the Lyapunov stability theorem. The presented control scheme along with the solar PV system is simulated in MATLAB (matric laboratory) (SMC controller and PWM (Pulse Width Modulation) part) and PSIM (Power electronics simulations) (solar PV and MPPT algorithm) environments using the Simcoupler tool. The simulation results of the proposed controller (SMC) are compared with the classical proportional integral derivative... [more]
Analysis of Dynamic Characteristics and Control Strategies of a Solvent Dehydration Distillation Column in a Purified Terephthalic Acid Plant
Xiuhui Huang, Jun Wang, Zeqiu Li
February 3, 2020 (v1)
Keywords: control strategies, dynamic analysis, solvent dehydration column
In this study, a solvent dehydration column of purified terephthalic acid (PTA) plant was used as the research object. Based on a dynamic model of the solvent dehydration column, a dynamic sensitivity analysis of the key parameters was carried out using Aspen Dynamics. After the dynamic model reached stability, the reflux rate, methyl acetate concentration, and reflux temperature of the solvent dehydration column were adjusted and the changes of the key separation indexes under the corresponding disturbance were analyzed. According to the analysis results, a sensitive plate temperature controller was added to carry out the dynamic sensitivity analysis. In addition, the acetic acid (HAc) concentration of the bottom of the column was found to be unstable in the dynamic sensitivity analysis. Considering the HAc concentration controller of the column bottom, two control strategies were designed. By analyzing the dynamic response of the feed flow disturbance under different control strategi... [more]
Static Deformation-Compensation Method Based on Inclination-Sensor Feedback for Large-Scale Manipulators with Hydraulic Actuation
Jianyong Qian, Qi Su, Fu Zhang, Yun Ma, Zifan Fang, Bing Xu
February 3, 2020 (v1)
Keywords: concrete pump, endpoint deviation, inclination sensor, large-scale manipulator, static deformation
Modern large-scale manipulators with hydraulic actuation like mobile concrete pump manipulators are increasingly used in industrial, construction, and other fields. Due to the large span of these manipulators, the static deformation accumulation to the endpoint has seriously affected the precise control of the endpoint. In this paper, we propose a static deformation-compensation method based on inclination sensor feedback for large-scale manipulators to reduce the deviation of the endpoint. Compared with the finite element method, this method does not need to consider many boundary conditions that are uncertain for flexible manipulators in most situations. It has appropriate accuracy and is universal for large-scale manipulators of different sizes and working under different loads. Based on a 24m-3R mobile concrete pump manipulator, the parametric simulation is carried out. The reliability of the static deformation-compensation method is verified, and the error is analyzed. The validit... [more]
Improved Genetic Algorithm Tuning Controller Design for Autonomous Hovercraft
Huu Khoa Tran, Hoang Hai Son, Phan Van Duc, Tran Thanh Trang, Hoang-Nam Nguyen
February 3, 2020 (v1)
Keywords: autonomous hovercraft, fuzzy-PID control, ISE criterion, modified GA
By mimicking the biological evolution process, genetic algorithm (GA) methodology has the advantages of creating and updating new elite parameters for optimization processes, especially in controller design technique. In this paper, a GA improvement that can speed up convergence and save operation time by neglecting chromosome decoding step is proposed to find the optimized fuzzy-proportional-integral-derivative (fuzzy-PID) control parameters. Due to minimizing tracking error of the controller design criterion, the fitness function integral of square error (ISE) was employed to utilize the advantages of the modified GA. The proposed method was then applied to a novel autonomous hovercraft motion model to display the superiority to the standard GA.
Economic Reliability-Aware MPC-LPV for Operational Management of Flow-Based Water Networks Including Chance-Constraints Programming
Fatemeh Karimi Pour, Vicenç Puig, Gabriela Cembrano
February 2, 2020 (v1)
Keywords: drinking water networks, economic cost, linear parameter varying, Model Predictive Control, operation and management, reliability
This paper presents an economic reliability-aware model predictive control (MPC) for the management of drinking water transport networks (DWNs). The proposed controller includes a new goal to increase the system and components reliability based on a finite horizon stochastic optimization problem with joint probabilistic (chance) constraints. The proposed approach is based on a single-layer economic optimization problem with dynamic constraints. The inclusion of components and system reliability in the MPC model using an Linear Parameter Varying (LPV) modeling approach aims to maximize the availability of the system by estimating system reliability. On the other hand, the use of a LPV-MPC control approach allows the controller to consider nonlinearities in the model in a linear like way. Moreover, the resulting MPC optimization problem can be formulated as a Quadratic Programming (QP) problem at each sampling time reducing the computational burden/time compared to solving a nonlinear pr... [more]
Triple-Mode Model Predictive Control Using Future Target Information
Minghao Chen, Zuhua Xu, Jun Zhao
February 2, 2020 (v1)
Keywords: dynamic matrix control, future target information, future trajectory horizon, Model Predictive Control
In this paper, we propose a triple-mode model predictive control (MPC) algorithm that uses future target information to improve tracking performance. To explicitly take into account the future target information in the MPC optimization, the proposed triple-mode control law encompasses three parts: (i) the future target information feedforward, (ii) the output feedback, and (iii) the extra degrees of freedom for constraint satisfaction. The first two parts of the control law are off-line designed through unconstrained MPC, and the optimal future trajectory horizon is obtained by golden section search based on the integral of squared error (ISE) criterion. The final part is calculated by the on-line MPC algorithm aiming to satisfy constraints. Furthermore, we analyze the feasibility and convergence properties of the proposed algorithm. The method is demonstrated by the simulation of the shell fundamental control problem and also tested on the coordinated control problem in the power plan... [more]
Nonlinear Structural Control Analysis of an Offshore Wind Turbine Tower System
Y. S. Hamed, Ayman A. Aly, B. Saleh, Ageel F. Alogla, Awad M. Aljuaid, Mosleh M. Alharthi
February 2, 2020 (v1)
Keywords: nonlinear PD controller, offshore wind turbine system, stability, vibration control
This paper investigates the vibration control, stability, and energy transfer of the offshore wind turbine tower system with control force and nonlinearity terms. A nonlinear proportional derivative (NPD) controller was connected to the system to reduce a high oscillation amplitude and to transfer the energy in the wind turbine system. Furthermore, the averaging method and Poincaré maps were used with respect to the controlled system to study the stability and bifurcation analysis in the worst resonance cases. The curves of force response and frequency response were plotted before and after the control unit was added to the wind turbine system. In addition, we discuss the performances of the control parameters on the vibration magnitudes. Numerical simulations were carried out with Maple and Matlab algorithms to confirm the analytical results. The results show the effectiveness of the NPD controller in suppressing the nonlinear oscillations of the wind turbine system.
Single Controller-Based Colored Petri Nets for Deadlock Control in Automated Manufacturing Systems
Husam Kaid, Abdulrahman Al-Ahmari, Zhiwu Li, Reggie Davidrajuh
February 2, 2020 (v1)
Keywords: Automated manufacturing system, colored Petri net, deadlock prevention, siphon
Deadlock control approaches based on Petri nets are usually implemented by adding control places and related arcs to the Petri net model of a system. The main disadvantage of the existing policies is that many control places and associated arcs are added to the initially constructed Petri net model, which significantly increases the complexity of the supervisor of the Petri net model. The objective of this study is to develop a two-step robust deadlock control approach. In the first step, we use a method of deadlock prevention based on strict minimal siphons (SMSs) to create a controlled Petri net model. In the second step, all control places obtained in the first step are merged into a single control place based on the colored Petri net to mark all SMSs. Finally, we compare the proposed method with the existing methods from the literature.
Integrating Feedback Control and Run-to-Run Control in Multi-Wafer Thermal Atomic Layer Deposition of Thin Films
Yichi Zhang, Yangyao Ding, Panagiotis D. Christofides
February 2, 2020 (v1)
Keywords: batch processes, control, data-driven modeling, design of batch processes, first principles modeling, monitoring, Optimization, quality control
There is currently a lack of understanding of the deposition profile in a batch atomic layer deposition (ALD) process. Also, no on-line control scheme has been proposed to resolve the prevalent disturbances. Motivated by this, we develop a computational fluid dynamics (CFD) model and an integrated online run-to-run and feedback control scheme. Specifically, we analyze a furnace reactor for a SiO2 thin-film ALD with BTBAS and ozone as precursors. Initially, a high-fidelity 2D axisymmetric multiscale CFD model is developed using ANSYS Fluent for the gas-phase characterization and the surface thin-film deposition, based on a kinetic Monte-Carlo (kMC) model database. To deal with the disturbance during reactor operation, a proportional integral (PI) control scheme is adopted, which manipulates the inlet precursor concentration to drive the precursor partial pressure to the set-point, ensuring the complete substrate coverage. Additionally, the CFD model is utilized to investigate a wide ran... [more]
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