Output feedback controller of a multivariable process

This paper addresses the nonlinear control design problem for a state-coupled two-tank liquid level system. For this system's dynamics, motivated by a desire to provide precise and economic liquid level control, a new output feedback control scheme is developed. In the proposed approach, a robust controller based on backstepping strategy is designed in order to ensure globally asymptotically stabilisation for a particular class of second-order nonlinear systems. Moreover , a model-based backstepping controller combined with a high gain observer is designed for the two-tank, liquid level system. Only one sensor is available to measure the liquid level in the bottom tank and the other process's state is assumed unavailable. The observer converges in a finite time and leads to good estimate of the liquid level in the top tank as well as a good track of the liquid level in the bottom tank with the reference trajectory. To highlight the efficiency and applicability of the proposed control scheme, a comparison with proportional plus integral plus derivative controller as well as a simulation and experimental results are provided.

IFAC Proceedings Volumes, 1993

In this stuoy concerning w ntrol of a laborat ory-scale thermal mixing tank, multiloop SISO control is compared with "model-based" control where the nonlinearity and multivariable characteristics of the process are explicitly taken into account. It is shown, especially if the operat ing range of the process is large, that the two outputs (level and temperature) cannot be adequately cont rolled by multiloop SISO control even if gain scheo uling is used. By nonlinear MIMO control baseo on exact linearizat ion very gooo control performance is obtai n ed. Two n on lin ear cont rol system designs based on a steady-state and a dynamic model are co nsidered. Hard input constraints are also handled.

2006

This paper deals with the control of a quadruple tank process. A gain scheduling controller, a linear parameter varying controller and an input-output feedback linearization controller are proposed for the quadruple tank process. The derivation of the three control schemes is presented in details. Moreover, the proposed control schemes are implemented using an experimental setup. The experimental results indicate that the developed control schemes work well and are able to regulate the output of the process to its desired value. Additionally, the implementation results demonstrate that the input-output feedback linearization controller gave the best performance.

Actuators , 2023

In this paper, two new versions of modified active disturbance rejection control (MADRC) are proposed to stabilize a nonlinear quadruple tank system and control the water levels of the lower two tanks in the presence of exogenous disturbances, parameter uncertainties, and parallel varying input set-points. The first proposed scheme is configured from the combination of a modified tracking differentiator (TD), modified super twisting sliding mode (STC-SM), and modified nonlinear extended state observer (NLESO), while the second proposed scheme is obtained by aggregating another modified TD, a modified nonlinear state error feedback (MNLSEF), and a fal-function-based ESO. The MADRC schemes with a nonlinear quadruple tank system are investigated by running simulations in the MATLAB/SIMULINK environment and several comparison experiments are conducted to validate the effectiveness of the proposed control schemes. Furthermore, the genetic algorithm (GA) is used as a tuning algorithm to parametrize the proposed MADRC schemes with the integral time absolute error (ITAE), integral square of the control signal (ISU), and integral absolute of the control signal (IAU) as an output performance index (OPI). Finally, the simulation results show the robustness of the proposed schemes with a noticeable reduction in the OPI.

The PID controllers are widely used in industry control applications due to their effectiveness and simplicity. This project presents PID controller design for MIMO coupled water tank level control system that is second order system. PID Controller output is fuzzified to control water level in coupled tank system. Simulation has been done in Matlab (Simulink library) with verification of mathematical model of controller. PID controller design and program has been prepared in LabVIEW. At the place of proportional valve, combinations of solenoid valves are used. The NI DAQ card is used for interfacing between hardware and LabVIEW software. Experiment is fully triggered by LabVIEW. Simulated results are compared with experimental results.

The paper deals with the study of SISO and MIMO processes using PID controller for a coupled tank process. The PID controllers have found wide acceptance and applications in the industries. In spite of their simple structures, PID controllers are proven to be sufficient for many practical control problems. This paper presents the PID controller design for controlling liquid level of coupled tank system. These coupled tank systems form a second order system. Simulation study was carried out for this process with more concern given to the heights of the tank & performance evaluating parameters are then determined.

2010

This paper proposes a simple approach to design a robust PI controller for an uncertain Coupled Tank system that will guarantee closed loop stability. The Robust Controller design method used here is based on Small Gain theorem. The controller is designed for a coupled tank process which is a good example for an uncertain system.The variable to be controlled is the liquid level in tank2. Inflow into tank1 is considered as the manipulated variable. The performance of the controller is evaluated using Settling time, Rise time and ISE. Simulation is carried out using MATLAB SIMULINK software.

In this paper we consider the laboratory 3tank system depicted on figure 1. For this specific system a special method of modelling must be considered. Valves between tanks have very low diameter, so the viscosity effects cannot be neglected. That leads to a conclusion, that a classical, based on Torricelli's law (flow from one tank to another is proportional to the square root of the water level) is not applicable. That is the reason why we approximate the flows with polynomials. For such model of the 3-tank system we are attempting to solve the problem of continuous state estimation from discrete output measurement (in this case the water level). Two different approaches will be considerednonlinear discrete-continuous observer and Newton observer. By discrete-continuous observer we understand the algorithm of continuous state estimation from discrete output measurements. Effectiveness of those observers will be illustrated with simulations, as well as with laboratory experiments.

2013

The project is concerned with the design of a water tank process and experimental evaluation of feedback control structures to achieve water level and temperature control at desired set point values. The manipulated variables are the pump power, on the water outflow line, and heat supply to the tank. Detailed, first principles-based, dynamic models as well as empirical models for this interactive and multivariable process have been developed and used for controller design. Furthermore, this experimental study entails and discusses the design of the water tank process and associated instrumentation, real time data acquisition and control using the DeltaV distributed control system (DCS), process modeling, controller design, and evaluation of the performance of tuning methodologies in a closed loop manner.