In this paper, a methodology of a web-based control and monitoring of the experimental pilot-plant installations is presented. The presented methodology provides scientists and engineers with an access to the experime...
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In this paper, a methodology of a web-based control and monitoring of the experimental pilot-plant installations is presented. The presented methodology provides scientists and engineers with an access to the experimental pilot-plants at the Institute of Automatic Control, and enables experiments to be carried out via Internet. A LabVIEW-based software is presented that allows distant programming of the experiments (both by specifying sequences of commands to be carried out, and by sending and executing dynamically loaded plugins used for realizing continuous control algorithms). As an example, control of the wastewater treatment experimental pilot-plant is presented.
The aim of this paper is to show practical application of programmable temperature control. Although control theory is very developed in this area there is still many interesting issues to solve applications. When tem...
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The aim of this paper is to show practical application of programmable temperature control. Although control theory is very developed in this area there is still many interesting issues to solve applications. When temperature my change in very wide range additional nonlinear process behaviour can be usually observed. To assure good performance programmable change in controller parameters is needed to achieve robust control performance. Presented application has several useful features as remote monitoring and programming.
Two different approaches for adaptive control design are investigated and compared from a user's point of view. The first one is an application of the Matlab toolbox routine Designer, and the second approach is ba...
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Two different approaches for adaptive control design are investigated and compared from a user's point of view. The first one is an application of the Matlab toolbox routine Designer, and the second approach is based on the commonly used adaptive linearising control (ALC) design method. The continuous aerobic fermentation of Saccharomyces cerevisiae is taken as an object for control. The control task is the stabilisation of ethanol production at a previously set low value of concentration. Simulations using a biochemical model of the process verify both algorithms. In general the obtained results for both algorithms satisfy the microbiologists' requirements. From a user's point of view, Designer shows more advantages then the ALC. The use of Designer seems to be promising for application in the bio-industry.
A new algorithm for automatic tuning of multivariable PI controllers for multi-input multi-output processes is presented. The tuning procedure consists of four stages. In the first, the critical point of each possible...
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A new algorithm for automatic tuning of multivariable PI controllers for multi-input multi-output processes is presented. The tuning procedure consists of four stages. In the first, the critical point of each possible loop is identified using the conventional relay feedback test. In this phase, a set of critical frequencies is formed. In the second stage, among the process critical frequency set, a design frequency is chosen. The choice of this design frequency is done with respect to the interaction problem in the multivariable system. In the third stage, the process steady state and frequency response matrices at the design frequency are estimated with good accuracy. In the fourth stage, the information about the process is used to tune the multivariable PI controller. For the multivariable PI controller, a new design technique is derived taking into account the decoupling condition at the low- and high-frequency range of the process. The proposed method is applied to various typical processes and experimented on using a laboratory-scaled model of a paper machine head-box. The experimental test has shown good results where significant performance improvement over the existing tuning methods is demonstrated.
In this paper a fuzzy control scheme, which employs the output feedback control approach, is suggested for the stabilization of nonlinear systems with uncertainties. The uncertain nonlinear system can be represented b...
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In this paper a fuzzy control scheme, which employs the output feedback control approach, is suggested for the stabilization of nonlinear systems with uncertainties. The uncertain nonlinear system can be represented by uncertain Takagi-Sugeno (TS) fuzzy model structure, which is further rearranged to give a set of uncertain linear systems. A switching-type fuzzy-model-based controller, which utilizes the static output feedback control strategy, is designed based on this preliminary study. Theoretical analysis guarantees that under the control of the proposed technique, the uncertain nonlinear system is stabilizable by the switching-type static output-feedback fuzzy-model-based controller. Finally, two computer simulation examples are provided to show the effectiveness and feasibility of the developed controller design method.
This work develops an intelligent scheduling controller (ISC) to support a shop floor control system (SFCS) to make real-time decisions, robust to various production requirements. Selecting near-optimal subset system ...
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This work develops an intelligent scheduling controller (ISC) to support a shop floor control system (SFCS) to make real-time decisions, robust to various production requirements. Selecting near-optimal subset system attributes (or features) based on various production requirements to construct ISC knowledge bases is a critical issue because of the existence of much shop floor information in an SFCS. Accordingly, this work developed a learning-based ISC methodology to acquire knowledge of a dynamic dispatching rule control mechanism. The proposed approach integrates genetic algorithms (GAs) and decision trees (DTs) learning to evolve a combinatorial optimal subset of features from possible shop floor information concerning a DT-based ISC knowledge classifier. A GA is employed to search the space of all possible subsets of a large set of candidate features. For a given feature subset, a DT algorithm is invoked to generate a DT. Applying the GA/DT-based knowledge learning mechanism to the experimental results demonstrates that the use of an optimal subset of system attributes to build scheduling knowledge bases enhanced generalization ability of the learning bias above that in the absence of an attribute selection procedure, in terms of prediction accuracy of unseen data under various performance criteria. Furthermore, simulation results indicate that the GA/DT-based ISC improves system performance in the long run over that obtained with classical DT-based ISC and the heuristic individual dispatching rule, according to various performance criteria.
Petri nets have been extensively applied for specification, design, veri cation, performance evaluation, and simulation of discrete event control systems (DECS). The usual way to verify the dynamic behaviour of DECS d...
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Petri nets have been extensively applied for specification, design, veri cation, performance evaluation, and simulation of discrete event control systems (DECS). The usual way to verify the dynamic behaviour of DECS design is to employ a process-based model, which proves to be impractical in application because the process-based model does not usually fully correspond to the control programming behaviour. This paper proposes a sensor-based stage Petri net (SBSPN) to represent a programmable logic controller (PLC) stage logic diagram (LD) for discrete-event control design. The new technique is able to simplify the modelling process of the complex PLC program without considering the interlocking problem within the ladder diagram. An illustrated example is used to explore the new methodology. The proposed method contains the power and flexibility of the Petri net analysis prior to the PLC implementation. It is believed that this technique is significant for industry practice.
CNC grinding machines are widely used to obtain a good surface finish and tight tolerances. However, these machines are expensive, therefore manufacturers are considering adding a grinding spindle, interchangeable wit...
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CNC grinding machines are widely used to obtain a good surface finish and tight tolerances. However, these machines are expensive, therefore manufacturers are considering adding a grinding spindle, interchangeable with a boring bar, to a turning lathe. To facilitate this, complex software is required because the programmer must control the whole surface of the grinding wheel not just the tool or cutter tip, as in turning or milling. This paper presents a general algorithm to simplify the grinding programme. The programmer will use this algorithm to create a subroutine suitable for the machine. The subroutine may then be used for all grinding operations. The programmer will need only to describe the contour of each workpiece, as for a CNC lathe program, in a separate small program. The algorithm has been applied to a hollow spindle lathe equipped with Sinumeric 840 C numerical control, and several gun barrels were turned and ground using the proposed approach. Satisfactory results were obtained.
Controller tuning is a basic step in any control application. This tuning is a complex process composed of several steps starting with the plant analysis and ending with the verification of the designed controller. Th...
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Controller tuning is a basic step in any control application. This tuning is a complex process composed of several steps starting with the plant analysis and ending with the verification of the designed controller. There are various tools that help in particular steps of the design but the complete path of the design is not supported. An attempt is made to offer a procedure of 'complete' controller design where all necessary steps follow automatically one after the other. The idea is applied to LQG controller design. The whole procedure is described and demonstrated on an example with the emphasis on the tuning of the LQG criterion to respect given constraints.
The reliable H-infinity controller design problem for uncertain descriptor systems with actuator failures and multiple time delays is investigated. Sufficient conditions to guarantee that the unforced system is regula...
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The reliable H-infinity controller design problem for uncertain descriptor systems with actuator failures and multiple time delays is investigated. Sufficient conditions to guarantee that the unforced system is regular, impulse-free and exponentially stable are derived. The derived conditions are expressed in terms of a set of linear matrix inequalities, which can be effectively solved by using well known algorithms. Then, based on these results, a reliable H-infinity controller is proposed such that, for all admissible uncertainties and actuator failures occurring among the prescribed subset of faulty actuators, the resulting closed-loop system is regular, impulse-free and exponentially stable with an H-infinity norm bound constraint. The effectiveness of the proposed method is demonstrated by a numerical example.
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