Liquid Level Control Research Articles

Comparative Study of Mamdani-type and Sugeno-type Fuzzy Inference Systems for Coupled Water Tank

The level and flow control in tanks are the heart of all chemical engineering system. The control of liquid level in tanks and flow between tanks is a basic problem in the process industries. Many times the liquids will be processed by chemical or mixing treatment in the tanks, but always the level of fluid in the tanks must be controlled and the flow between tanks must be regulated in presence of non-linearity. Threfore, in this paper will use fuzzy inference systems to control of level 2 are developed using Mamdani-type and Sugeno-type fuzzy models. The outcome obtained by two fuzzy inference systems is evaluated. This paper summarizes the essential variation among the Mamdani-type and Sugeno-type fuzzy inference systems with setpoint of level is 10 centimeter. Matlab fuzzy logic toolbox is used for the simulation of both the models. This also confirms which one is a superior choice of the two fuzzy inference systems to control of level 2 in tank 2. The results show madani-type fuzzy inference system is superior as compared to sugeno-type fuzzy inference system.

Design and implementation of training module for control liquid level on tank using PID method based PLC

Process control is widely used in various industries to maximize production, maintain desired quality levels, product safety and make the process more economical. Control that is generally used in industry is to control liquids, such as controlling the level, flow, pressure, and temperature of the liquid using the Proportional-Integral-Derivative (PID) method, the PID controller attempts to correct errors between the measured process variables and the desired set-point by calculation and then issue actions corrective which can be arranged according to the process. In the past, most PID controllers were based on microcontrollers, but now Programmable Logic Controller (PLC) can also operate PIDs with analog function control because PLC speeds and capabilities have increased. To meet the needs of student competence in process control following industry demands, especially the use of PLC with the PID Method, students need to be given knowledge and skills. One way is the availability of training modules that can grow their enthusiasm and skills when they learn. This paper presents the design and implementation of PLC Omron CP1H based process control training modules that can be used by students to study liquid level control in tanks with PLC-based PID methods. Based on the test results when the plant is disturbed, the system response obtained by the PID method is a 15 second settling time, 10.9% undershoot, and a steady-state value of 14.6 cm or ± 97.3% of the 15 cm setting value.

Level Control of Quadruple Tank System Based on Adaptive Inverse Evolutionary Neural Controller

This article proposes an adaptive inverse evolutionary neural (AIEN) controller for liquid level control of the quadruple tank system. Firstly, an inverse evolutionary neural model (IEN) that is utilized for offline identifying a dynamics of quadruple tank system, provides a feed-forward control signal from the reference liquid level. In which, the evolutionary neural model is a 3-layers neural network that is optimized by a hybrid method of modified differential evolution and backpropagation algorithm. Then, a hybrid feedforward and PID feedback control is realized to eliminate the steady-state error. Finally, to solve an uncertainty and disturbance characteristic, an adaptive law is proposed to adopt online in its operation. Simulation and real-time control experimental results demonstrated the feasibility and effectiveness of the proposed approach for the quadruple-tank system.

Design of an optimal observer for making liquid level control loop robust to variations in transmission parameters

The interconnected system has become the need of the hour in the present day industrial automation. Interconnection is established by conventional wired or by wireless techniques. In either case fo...

Non-Linear Tank Level Control for Industrial Applications

Tank level control is ubiquitous in industry. The focus of this paper is on accurate liquid level control in single tank systems which can be actuated continuously and modulation of the level setpoint is also required, for example in cascade control loops or supervisory Model Predictive Control (MPC) applications. To avoid common problems encountered when using fixed gain or adaptive/gain scheduled schemes, an accurate technique based around feedback linearization and Proportional Integral (PI) control is introduced. This simple controller can maintain linear performance over the full operating range of a uniform tank. As will be demonstrated, the implementation overhead compared to a regular PI controller is negligible, making it ideal for industrial implementation. Implementation details and parameter identification for adaptive implementation are discussed. Simulations coupled with experimental results using a large-scale laboratory level control system using commercial industrial control equipment validate the approach, and illustrate its effectiveness for both level tracking and disturbance rejection.

Robust Liquid Level Control of Quadruple Tank System - Second Order Sliding Mode Approach

In this paper, second order sliding mode control is proposed for liquid level control in a quadruple tank system. The system has internal cross coupling in its four tank setup, and realizes in a nonlinear model. The proposed twisting algorithm (TA) based controller is complemented with an exact differentiator for estimating the derivatives of the outputs. Simulation results are provided to validate the efficacy of the proposal.

Design of liquid level control system for double tank

In order to control the liquid level in the chemical production process, a PID control theory algorithm is proposed. Firstly, by constructing a double-capacity water tank liquid level control system, the mathematical model of the double-capacity water tank was deduced and constructed through many experiments. The simulation was carried out by Matlab Simulink software, and the dynamic and static characteristics of the double tank water level control system were analyzed based on the simulation results. The Labview software was used to write the algorithm of the double tank water level control system. The USB-6008 data acquisition card and the DAQ data acquisition assistant were used to complete the connection of the experimental hardware and software. The actual liquid level curve was obtained through experiments. The experimental results show that the designed system can keep the liquid level of the lower tank of the double tank level within the set value, and the floating does not exceed 5%, which achieves the predetermined steady state effect.

Comparison of MATLAB Simulink application with PLC application of real-time classical PID controllers in laboratory

Process control is a common area of study for different engineering disciplines. Controllers working ‎with ‎the ‎proportional–integral–derivative (PID) method are generally used in process control. ‎Parameters like ‎level, ‎flow, position, pressure, and temperature are controlled in-process control. PID ‎algorithm can be ‎formed ‎with different microprocessor-based devices. Process control is ‎implemented by using analog input ‎and ‎outputs terminals of PLCs (Programmable logic controller) ‎which is recently the most commonly used ‎in ‎industries. Also, a real-time PID method can be ‎implemented by using a computer-based ‎MATLAB ‎ ‎program in the laboratory.‎ The liquid level and flow control in the laboratory has been done by using PID algorithms and ‎PLC ‎device ‎and MATLAB real-time interface by using an experimental set. Necessary connections ‎and ‎configurations have ‎been prepared to perform process control. (SIMATIC Manager Step7) is ‎used for ‎programming in PLC. ‎Besides, the MATLAB simulation program is configured to implement ‎real-time ‎control to be ‎compatible with the MF624 data acquisition card. Liquid level and fluid flow ‎control ‎experiments were ‎performed separately for the same PID algorithms formed on two different ‎devices, then ‎liquid level ‎detection and liquid flow control results have been collected and ‎investigated. Based on these ‎results, a total ‎of four experiments were compared with both devices ‎considering the ease and difficulties of ‎using PLC and ‎MATLAB.‎

The Design of a Microcontroller-based Automatic Liquid Level Control System

In this paper, a liquid level control system was designed and fabricated. Control of the liquid level was accomplished by adjusting the sup-ply voltage to a centrifugal pump that is delivering the liquid from a reservoir tank to an upper tank. The liquid level control system was implemented on an ATmega328 microcontroller. Three control strategies are implemented, manual mode, ON/OFF controller, and PID controller. Serial communication is used to establish the communication between the ATmega328 and a computer running MATLAB soft-ware. A graphical user interface was constructed to allow users to interact with the system. The system model is obtained using an experi-mental approach. The obtained model is then used for the design of the PID controller. Experimental results are provided to highlight the performance of the implemented controllers.

Novel fuzzy fractional order PID controller for non linear interacting coupled spherical tank system for level process

In this paper, a novel Fuzzy Fractional Order Proportional Integral Derivative (FFOPID) controller is proposed to control the liquid level of Two Tank Spherical Interacting System (TTSIS). Spherical tanks are widely used in process industries due to its high storage capacity. These are non-linear due to its varying surface area with respect to its height and hence the level control of a spherical tank system is a challenging task. Fractional Order Proportional Integral Derivative (FOPID) controller is designed for a liquid level control of a spherical tank which is modelled as a fractional Order System. The performance indices such as rise time, settling time, peak time and peak overshoot are analysed for the proposed control scheme and compared to conventional controllers such as PI, PID, PID-SMC, FOPID. Moreover the time integral performance measures such as ITAE, IAE and ISE are analysed. Experimental results are shown to validate the obtained results with those of simulations. It has been proven that FFOPID outperforms all other existing techniques in terms of various time domain specifications and time integral performance measures.

Fractional Order PI Controller for Nonlinear Processes using Binomial Theorem Approximation

In Most of the process industries, Integer order Proportional Integral controller (IOPI) has been designed for different processes due to its simplicity but it will damage the final control element due to the sudden change in controller output. So, this research work proposed to eliminate the ringing phenomena by applying large pure time delay in the controller output by proposing Fractional Order Proportional Integral (FOPI) controller using Binomial theorem approximation for the nonlinear conical and spherical tank level processes. The control of liquid level in the nonlinear tank is arduous in nature due to an imbalance in the area of the transverse section of the tank. The robustness of the IOPI and FOPI controllers has demonstrated in Time Domain Specifications (TDS). The FOPI controller eliminates the peak overshoot in the process variable and ringing effect in controller output to protect the pneumatic positioned control valve.

A Model and Multi-Mode Control of a Centrifugal Chiller System: A Computer Simulation Study

In this paper, a model of a water-cooled centrifugal chiller system is developed and its control performance is studied. The overall system consists of three control loops: (i) a compressor speed control; (ii) an inlet guide vane control and (iii) a condenser liquid-level control. The model is validated by comparing the simulation results with the experimental data under steady state conditions. The results match to within 10% accuracy. A multi-mode control strategy was designed to simulate the operation of the centrifugal chiller as it transitions between start-up, speed control mode, IGV control mode and shutdown mode during a typical day operation. COP of the chiller was studied by conducting simulation runs under a wide range of operating conditions. The results showing the coefficient of performance of the system at different cooling loads as a function of cooling water temperature under IGV control mode and compressor speed control mode are presented.

LQR Based Optimal Tuning of PI Controller for a Conical Tank Level Process

The liquid level control in conical tank is tough task owing to variable cross-sectional area. The replica of the conical tank is recognized using standard step test technique and is approximated to be FOPTD model. In this paper, PSO based LQR-PI controller has been wished-for conical tank system. The PI controller gains are formulated as the optimal state-feedback gains. A PSO has been accustomed optimally to discover the weighting matrices, related to the various optimum state- feedback regulator design whereas minimizing ISE and the controller effort. The performance of the proposed PSO based LQR-PI controller is contrasted with those of GA-LQR-PI and LQR-PI controllers.

Modeling and simulation of a falling film evaporator for a water vapor heat pump system

With the advantages of excellent heat transfer performance and less refrigerant charge, falling film evaporator has been widely used in seawater desalination and other industries. However, due to the practical problems of liquid level control and dry patches interactions, the structure design of falling film evaporator should be optimized for refrigeration applications. To resolve those problems, a simulation model for water-to-water falling film evaporator used in a water vapor heat pump system was conducted in this paper. Through the finite element method, the temperature distribution along the working tubes and the heat exchanger has been obtained. The distribution of heat transfer coefficient along the tube is also investigated to find out the best liquid level control solutions. For an available falling film evaporator with 4 pass working tubes under boiling temperature of 80 °C and spraying mass of 0.4 kg⋅s−1, it is suggested that 2 pass working tubes should be in falling film region in order to achieve the largest heating capacity. Most important of all, it is proposed that there is an optimal boundary line between full liquid and falling film region. It may provide some suggestions for future design of falling film evaporators.

Model-Free Controller for Two Tanks Liquid Level Control

Model-Free Controller for Two Tanks Liquid Level Control

Design of output feedback controller for stochastic feedforward systems with unknown measurement sensitivity

This paper investigates the problem of output feedback control for a class of stochastic feedforward systems with unknown measurement sensitivity. Unknown measurement sensitivity is only a bounded continuous function and its derivative is not guaranteed. To solve the considered problem, the low-gain linear K-filters are performed without using the information of the output, and a gain design method based on backstepping is proposed to construct an output feedback controller. By the stochastic stability theory, the asymptotically stable in probability of the closed-loop control system is analyzed. A nonlinear liquid level control resonant circuit system with unknown measurement sensitivity is given to demonstrate the effectiveness of the proposed control scheme.

Simulation Tool for Tuning and Performance Analysis of Robust, Tracking, Disturbance Rejection and Aggressiveness Controller

The RTD-A (robust, tracking, disturbance rejection and aggressiveness) controller is a novel control scheme that substitutes the classical proportional integral derivative (PID) controller. This novel controller’s performance depends on the four controller tuning parameters (θR, θT, θD and θA). The tuning of RTD-A controller is more transparent than classic PID controllers. The RTD-A tuning parameters values lies between ZERO and ONE. Availability of a tool to design optimal parameters for this controller and evaluating the performance on a given system is necessary for the researchers. In this paper, the new simulation tool is presented to deal with the RTD-A control scheme. There are four graphical user interface tools included in the proposed tool and working of each tool is explained in detail. To demonstrate the proposed tool, two examples, which involve a liquid level control application and an air pressure control application, are presented in this work. The performance of the RTD-A controller is compared with PID controller. RTD-A controllers are tuned using optimization algorithms and their performances are observed and analyzed in both cases under deterministic and uncertain conditions.

The design and implementation of a fuzzy gain-scheduled PID controller for the Festo MPS PA compact workstation liquid level control

Due to the high-quality standards required by the process control industry such as liquid-level control, it is desired to implement sophisticated controllers that ensure the proper functioning of the process. Currently most industrial controllers are of the classic PID type. These controllers do a good job in reducing the system error and have simple structure and can be tuned easily when compared to fuzzy gain scheduled PID controllers. However, classic PID controllers do not perform well when the controlled system possesses largely varying dynamics at different operating conditions. Another limitation of classic PID controllers is that their operation depends on the tuning of the proportional, derivative, and integral gains. This paper presents a comparative study between a fuzzy gain scheduled PID controller and a classic PID controller commonly implemented in the process control industry. A comprehensive mathematical model for the Festo MPS PA compact workstation is developed for future use for control system design of the MPS PA compact workstation. Based on the experimental results, the fuzzy gain scheduled PID controller demonstrated supremacy on the PID control strategy. The presented analysis is verified by the implementation of the fuzzy gain scheduled PID control algorithm in the MPS PA compact workstation using custom-built LabVIEW interface. Experimental results verified the effectiveness of the proposed control scheme.

Design of a robust optimal decentralized PI controller based on nonlinear constraint optimization for level regulation: an experimental study

This paper presents the development of a new robust optimal decentralized PI controller based on nonlinear optimization for liquid level control in a coupled tank system. The proposed controller maximizes the closed-loop bandwidth for specified gain and phase margins, with constraints on the overshoot ratio to achieve both closed-loop performance and robustness. In the proposed work, a frequency response fitting model reduction technique is initially employed to obtain a first order plus dead time &#x0028 FOPDT &#x0029 model of each higher order subsystem. Furthermore, based on the reduced order model, a proposed controller is designed. The stability and performance of the proposed controller are verified by considering multiplicative input and output uncertainties. The performance of the proposed optimal robust decentralized control scheme has been compared with that of a decentralized PI controller. The proposed controller is implemented in real-time on a coupled tank system. From the obtained results, it is shown that the proposed optimal decentralized PI controller exhibits superior control performance to maintain the desired level, for both the nominal as well as the perturbed case as compared to a decentralized PI controller.

Application of Fuzzy Control in a Wireless Liquid Level Simulator

Liquid level control has great proposition in terms of chemical processes. It is important to make the level measurement in the tanks filled with industrial liquids with accurate and reliable equipment and to keep the liquid level at a certain level. In the studies conducted, wireless liquid level control was performed in a process control simulator system. For all computation and data processing procedures, the MATLAB program is used on-line connected to the system where the liquid level system is located. Then, the behavior of the output variable is examined by giving various effects to the liquid level valve opening selected as the setting variable. Fuzzy control of the system was performed by using the most suitable model found in the operating conditions obtained in dynamic studies. Wireless on-line computer control systems are used for this. The best control efficiency was obtained when the values were 4 dm.