Closed-loop Fuzzy Control Research Articles

Stable adaptive fuzzy control for a class of interconnected systems

The problem of adaptive fuzzy control for a class of interconnected systems with both unknown constant control gains and unknown function control gains is studied in this paper. By using fuzzy modeling method, a design scheme of stable adaptive fuzzy controller is proposed. According to the Lyapunov method, the closed-loop fuzzy control system is proved to be globally stable, with tracking errors conversing to a neighborhood of zero. Finally, the simulation results are given to demonstrate the effectiveness of the approach.

Stable and optimal fuzzy control of linear systems

A number of stable and optimal fuzzy controllers are developed for linear systems. Based on some classical results in control theory, we design the structure and parameters of fuzzy controllers such that the closed-loop fuzzy control systems are stable, provided that the process under control is linear and satisfies certain conditions. It turns out that if stability is the only requirement, there is much freedom in choosing the fuzzy controller parameters. Therefore, a performance criterion is set to optimalize the parameters. Using the Pontryagin minimum principle, we design an optimal fuzzy controller for linear systems with quadratic cost function. Finally, the optimal fuzzy controller is applied to a ball-and-beam system.

Total Intravenous Anaesthesia with an Integrated Computer Control System

An integrated multivariable computer control system is currently under development to assist anaesthetists in the administration of anaesthetic, analgesic and muscle relaxant infusions for total intravenous anaesthesia This multivariable system is the integration of several single variable systems developed by the research team. A serimultiplexer, vas developed by the research team to allow communication of multiple infusion and monitoring devices via a single computer serial port. Initially the system was arranged with pharmacokinetic model-driven systems for the anaesthetic and analgesic agents and a Relaxograph (Datex) monitor was used for fuzzy closed-loop control of neuromuscular block (NMB).

ANALYSIS OF FUZZY CLOSED-LOOP CONTROL SYSTEMS BY RELATIONS

As for fuzzy closed loop control systems composed of fuzzy relation de scribed process and controller this paper proposes an analytical method for the stability of fuzzy closed loop control systems using fuzzy relations and a design method for constructing a stable fuzzy controller As a result the paper develops the theory of fuzzy control systems Examples are given to illustrate how to use the method for the analysis and design of fuzzycontrol systems

Linguistic stability analysis of fuzzy closed loop control systems

A linguistic analysis method for fuzzy closed loop control systems where both fuzzy controller and controlled processes are described by linguistic rules is proposed in this paper. First, a linguistic relation model of a fuzzy closed loop control system is deduced from the linguistic rule models of the fuzzy controller and the controlled process. Then the linguistic stability of the fuzzy closed loop system is discussed by a linguistic relation matrix. Finally an example is given to illustrate the proposed method.

Analysis and synthesis of fuzzy closed-loop control systems

In this paper, the sufficient and necessary conditions on stability of fuzzy closed-loop control systems are formulated. Based on the sufficient condition of stability, an algorithm is presented to synthesize stable fuzzy controllers. An example for synthesizing a fuzzy control system is given to show that the method is available.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multilevel intelligent fuzzy control of oversaturated urban traffic networks

Some drawbacks of existing automated urban traffic control systems are discussed. It is shown that most of them are based on deterministic algorithms and have a centralized structure. As a result, qualitative and quantitative complexity of transport processes are not taken into account effectively. To overcome this inconvenience, an approach for implementing distributed intelligence systems is proposed. It is based on multilevel and artificial intelligence techniques. Fuzzy sets theory is chosen as a tool for distributed intelligence control systems design and a specific method is presented. It is shown, however, that this method is not suitable for real time control of large scale systems and an alternative method, leading to a closed-loop fuzzy control law, is proposed. It is based on decomposition of the system into subsystems and presentation as a hierarchical two-level control structure. In this case, the controls have two components—local (calculated by the lower level) and global (calculated by the...

A rule-based postoperative pain controller: Simulation results

We describe a system for controlling postoperative pain, a phenomenon that is difficult to treat by conventional control methods due to interpatient variability, interferences, non-linearity and the lack of a plausible, well-defined mathematical model. The system consists of two phases. In Phase 1 a closed-loop fuzzy controller implementing a suitable control strategy brings the patient to a zero-pain state. In Phase 2, an open-loop computer-assisted continuous infusion controller maintains a constant concentration of the analgesic (alfentanil) in plasma, subject to an upper safety limit on infusion rate; the setpoint of this controller is periodically revised (either maintained or reduced) on the basis of feedback on the duration of zero pain (setpoint reduction is necessary because the open-loop system has no means of knowing whether analgesic is accumulating in the patient). Pain is quantified by the patient on a numerical scale of 1 to 10 at 1.5-min intervals during Phase 1 and 9-min intervals during Phase 2. In simulation trials in which a fixed approximate model was used for the effect of sedation on pain while the pharmacokinetics of alfentanil were varied from one simulated patient to another, zero pain was achieved in under 15 min with minimal overshoot in plasma drug concentration and was maintained, with only minor deviation, by means of low drug concentrations.

Study on stability of fuzzy closed-loop control systems

The problem of stability of fuzzy closed-loop control systems has long been unsolved. Through analyzing the max-min composition operator in fuzzy systems, this paper presents a reasonable analytical model of fuzzy closed-loop systems, and then proposes a method to analyze the stability of control systems by the relational matrix of fuzzy systems. An example is given to show the method available.