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A set of explicit expressions for an accurate identification of unstable first order plus time delay (FOPTD) process using single relay feedback test are deduced. Thereafter, tuning rules for a feedforward and feedback combination of proportional-integral and proportional controllers are proposed to enhance the closed loop transient performance. When the process output is distorted by measurement...
The paper describes how to model and control performance of a trusted web server using Feedback Error Learning and H∞ control theory. Web server load may experience enormous variations and unpredictability. Existing web servers are difficult to achieve performance guaranties in such environment. One of challenges in web server research is how to model non-linearity computing systems. We demonstrate...
In the application of feedback controls, the computation of the controls may cause a delay. For vibrating systems, a constant delay can destroy the stabilizing effect of the control. To avoid this problem we consider a feedback where a certain delay is a part of the control law and not a perturbation. We consider a string that is fixed at one end and controlled with a boundary feedback with constant...
Aiming at such characteristics as severe non-linearity, time-delay existing in Alkaline Pefoxide Mechanical Pulp (APMP) wastewater aerobic treatment process, after giving a variable parameter bounded mathematical model of the activated sludge biological treatment process, a novel control method based on expert system (ES) is proposed in this paper. The basic idea is concluded as follows: A feedforward...
A novel model-deviation compensation control strategy is developed for a class of uncertain systems with time delay in this paper. Taking an identified second-order plus dead-time (SOPDT) process for example, the whole design methodology is proposed, which integrates the prediction model, the sliding function design, the equivalent control term and the model-deviation compensation control law. Firstly...
The modified Smith predictor is well known as an effective time-delay compensator for a plant with large time delays, and several papers on the modified Smith predictor have been published. The parametrization of all stabilizing modified Smith predictors for minimum-phase time-delay plants is obtained by Yamada and Matsushima. In addition, Yamada et al. expanded the result by Yamada and Matsushima...
The mathematical models of each process link consumption in water purification systems were established by means of the mechanism method, and the model for optimal coagulant dosage was given by setting the sum of those units as the objective function. To take into consideration large time delay and disturbance characteristics in the coagulation sedimentation process, a forward-feedback control method...
This paper presents an initial friction compensation by a disturbance observer in the fast and precise positioning of ball screw-driven table systems, on the basis of a rolling friction model. The rolling friction behaves as a nonlinear elastic element in the table drive mechanism, especially in the micro-displacement region, deteriorating the fine positioning performance. Effects of the rolling friction...
As manufacturing quality has become a decisive factor in competing in a global market, statistical process control (SPC) is becoming very popular in industries. With advances in sensing and data capture technology, large volumes of data are being routinely collected in automatic controlled processes. There is a growing need for SPC monitoring and diagnosis in these environments, SPC (statistical process...
Under the perspective of a control education bridging the gap between theory and practice, this paper presents the control challenges for a MIMO time-delay process (a laboratory plant based on a heat-exchanger). Diagonal and full matrix control strategies are exposed taking into account performance limitations of feedback control and non-minimum phase plants.Then, certain implementation issues are...
This paper considers the stabilization problem of linear systems with n + 1 poles and a time delay tau. First, the conditions for the existence of a stabilizing control by static output feedback are done. Subsequently, the conditions for the existence of a predictor scheme are established. Finally, the application of the results are illustrated with three academic examples.
In terms of double-controller design technology and relay feedback identification method an autotuning IMC structure with two degree of freedom (TDF-IMC) is proposed in this paper. The model parameters of the controlled process are identified via a modified relay feedback identification method. The setpoint tracking IMC controller and disturbance attenuation IMC controller are designed, respectively,...
This paper is devoted to integrated control-scheduling in the case of embedded systems with communication delays, i.e. network induced delay and input output latency. Moreover the system control design takes into account the unknown delays due to the temporal uncertainties that are unavoidable in real-time environment, and embedded systems are featured by their limited resources. So, the performance...
This paper presents the structure and algorithm of a new fuzzy logic controller which contains a feedback of control action in its input and therefore is called dynamic fuzzy controller, mainly studies the first-order dynamic fuzzy controller and six new corresponding fuzzy inference rules are given. The results show that the performances of the control systems with the first-order dynamic fuzzy logic...
Material or fluid transportation is a commonly encountered phenomenon in industrial applications, generating variable time delay that makes the design of feedback control loops more difficult. This paper investigates the applicability of MPC (Model Predictive Control) strategies to this type of processes. The experimental setup consists of a heated tank, of which the outlet temperature (measured at...
The control system of AFPT (air flow pressure and temperature) pilot plant has been used successfully to demonstrate the design of some controllers such as PID, cascade PID and fuzzy logic controller. It is important to develop a gas density control system in the AFPT pilot plant since gas density is one of the gas properties which need to be set precisely in few processes. The control system is designed...
An active disturbance rejection controller (ADRC) is proposed for decoupling double-loop control system. The ADRC consists of the tracking differentiator, the extended state observer and the nonlinear state error feedback. With this approach, the double-loop system with time delay is treated as two correlated control loops according to the best variable pairs selection, the interactions of two control...
Aiming at unstable processes with large time delay in chemical industry, a modified internal model control method is proposed based on internal model control (IMC). The structure of new control method consists of inner-loop control and outerloop control. The separately design step is used to design forward-feedback controller for disturbance rejection and the IMC controller for set-point tracking...
Coke oven heating temperature was reflected by flue temperature and adjusted by gas flow. Aiming at the coke oven heating process characteristics of great inertia, pure time-delay, strong non-linear and time changeable, the control method of combining the intermittent heating control with the heating gas flow adjustment was adopted. Hybrid intelligent control strategy and model of coke oven heating...
This work approaches the problem of robust control for first-order plus time delay plants. The goal is investigate the potentials of a nonlinear/hybrid compensator previously developed by authors, referred to as the PI+CI compensator, in the control of a process with significant parametric uncertainty. To this end, the design of PI+CI has been made in two steps: first, a base robust PI compensator...
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