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Fibre Chemistry, Vol. 45, No. 2, July, 2013 (Russian Original No. 2, March-April, 2013)

TECHNICAL SOLUTIONS FOR OPTIMUM CONTROL OF COMPLEX

DYNAMIC OBJECTS IN THE PRODUCTION OF NONWOVENS

V. A. Dubovitskii,* A. E. Polyakov,* UDC 621.798.426-52K. A. Polyakov,** A. V. Chesnokov,*and E. M. Filimonova*

The problem of improving the quality indices of nonwovens is examined and is solved by optimizing

control of the speed regimes of the electromechanical systems used in their production. The use of amulti-motor electric drive in combination with monitoring of the physico-mechanical properties of the

fibrous product during the various conversions makes it possible to correct the speed regimes of themachines in the flow line. The authors construct and analyze a functional model of a modernized

control system for an automated line designed for the production of bulk nonwovens. Technical solutionsfor optimizing control of the complex’s high-speed operating regimes are presented to illustrate the

use of the model.

The production equipment used to make nonwovens has several distinguishing characteristics that influence theformulation and method of solution of the problem of making this equipment more energy-efficient by controlling itshigh speed operating regimes [1]. The conditions that must be met in order to reliably stabilize the process parametersfor forming and winding fibrous materials impose stringent requirements on automated control systems (ACSs) in regardto their ability to maintain the specified speed regimes and product-quality indices.

The main factors to consider in the design of controlled electromechanical systems (CEMs) are the physico-mechanical properties of the fibrous product that is being made - strength, draft, space factor, winding density, andelastic, delayed-elastic, and plastic deformation during drawing.

One effective approach to determining the structure of a CEM is to use perform kinematic and dynamic analysesof the functioning of its equipment. Allowing for the effects of different factors (electromagnetic processes, flexibleconstraints, elasticity in the mechanical transmissions, etc.) makes the structure of the CEM more complicated and itsdescription more detailed. The use of a synergistic approach shows that, taken as a group, these factors have a differenteffect on the system than the effect realized when each factor is taken into account separately. This was confirmed by theresults presented in [2].

Developing an effective control system requires study of complex dynamic objects and technological processes.The most accessible means of theoretical investigation is to mathematically model machines and their components byemploying systems of differential and algebraic equations. The systems of differential equations that are used do nothave algebraic solutions in most cases, so recursive algorithms which entail integration over a specified range of loadsare used to find a solution.

Mathematical models make it possible to study the behavior of a system in which the control variables andperturbations vary widely in amplitude and spectral composition.

*Moscow State Textile University and **The Institute of Radio Engineering. Translated from KhimicheskieVolokna, No. 2, pp. 59-61, March-April, 2013.

0015-0541/13/4502-0119 © 2013 Springer Science+Business Media New York

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The ACS indices that characterize the static and dynamic properties of a given CEM reveal the optimum valuesof the perturbations and thus make it possible to construct optimum control laws.

The well-known control algorithms currently in use were developed based on knowledge of a mathematicaldescription of the object that is accurate to within a finite number of constant parameters. In actuality, constructing anaccurate model of an object is quite difficult and sometimes impossible. Use of the latest methods and technologies doesmake it possible to avoid exactly replicating the nonlinearity of the object. In such cases, the control system is designedfor a higher level of uncertainty. The use of this approach allows an order-of-magnitude improvement in the dynamicprecision with which complex dynamic objects equipped with transporting and winding mechanisms can be operated inhigh-speed regimes.

The hardware employed to realize modern technologies provides for the use of highly co-integrated flexiblemicrocontrollers, programmable logic controllers, microcomputer expansion boards, etc. However, the high cost of theelectronic components of the power equipment and control equipment in electric drives is a roadblock to the developmentand introduction of artificial-intelligence based systems for controlling the operation of electrical systems.

A new conceptual framework has been developed to design, test, and build a complex electromechanical systemfor making nonwovens. Matlab programs such as Simulink, Neural Network Toolbox, and Fuzzy Logic Toolbox wereused along with the electric-circuit modeling program Multisim to mathematically model and design the CEM.

The method of electrical modeling [3] was used to account for the properties of the fibrous product and thedynamics of its movement during its forming and transport. This approach is based physically on the method ofelectromechanical analogies, i.e. the CEM is represented in the form of equivalent electric circuits.

Comparison of the structural model with the model obtained by making a direct analogy between the CEM andelectric circuits shows that the latter is more illustrative because each mechanical element has its own electricalrepresentation. Structural models are realized with the use of modern microcomputers and the appropriate software.

The electric circuit remains an illustrative and generalizing image of the system being modeled even when anindirect method is used, thanks to the advantages of electrical analogies. The modeling is performed using a special“four-pole” method. Here, the model is analyzed and corrected in parts by performing additional experiments on partialsystems that can be analyzed separately from one another by (for example) introducing perturbations, linearizing, orusing other tools.

Proceeding on the basis of the method of electromechanical analogies, we have proposed a structure for amechanical model of a fibrous product and have analyzed the deformation zones. The drafting zone was studied forstability and the presence of free vibrations. The drawing regime used for the fibrous product was subjected to parametricoptimization in order to obtain a transient of satisfactory quality. That made it possible to optimize the parameters for thehigh-speed regimes of the system being studied.

We constructed and studied a functional model of a modernized control system for an automated line designedfor the production of bulk nonwovens [4]. The objective was to ensure the manufacture of a product of the prescribedquality on an energy-saving electrotechnical complex.

To illustrate the use of the model that was developed, we will present technical solutions for optimizing controlof the complex’s high-speed operating regimes.

The automatic scales used with carding machines usually have a single electric drive for the spiked latticeconveyer, which operates periodically. The other parts of the scales are brought into motion by the main motor of thecarding machine. Study of the static and dynamic characteristics of the automatic scales of these machines shows thatthe quality of the outgoing float depends both on the constancy of the mass of the batch of fibrous material and onmatching of the speeds of the scales’ working elements: the distributing eccentric, compacting plate, spiked latticeconveyor, etc.

We are proposing the use of a two-motor electric drive that can synchronize the speed regimes of the scales’working elements with the machines and other equipment in the flow line. The presence of the additional motor wouldallow for smooth and independent control of the rotary speeds of the elements. In this case, the load on the cardingmachine would be consistent with the value required for the scales’ coefficient.

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Study of the metrological characteristics of the relay system of automatic scales showed that it is possible toreduce fluctuations in the mass of the batches of the fibrous mixture by using strain gages instead of the scale mechanismand by modifying the algorithm used to control the speed of the grid [5].

When elements of the unit that processes the carded material are brought into motion by the main drive of thecarding machine, they sometimes strike the housing as the carriages change direction. There are two ways to solve thisproblem: make a complicated adjustment to the mechanism in the existing system; use individual motors. The secondmethod is preferable to ensure smooth and independent control of the speeds, although it will also require synchronizationof the speeds of the carded material along the conveyor belts.

In the patented system [4], the speeds of the working elements are synchronized with the use of a transducerthat measures rotational velocity. The signals corresponding to the set points for the electric drives are formed in a groupof microprocessors. The load on the carding machine and the linear density of the finished cloth are kept constant whilethe carding machine is in operation. Monitoring of the quality of the cloth makes it possible to correct the speed regimesof the machines in the flow line.

The above theoretical models of CEM components and the results obtained from mathematically modelingindices that characterize the performance of the system provide empirical proof of their reliability.

REFERENCES

1. A. E. Polyakov and K. A. Polyakov, Tekst. Prom-st’, No. 2, 28-30 (2005).2. A. E. Polyakov. Optimizing the Efficiency of Textiles Manufacturing by Controlling the Speed Regimes of

Electromechanical Systems in the Production Equipment. Author’s Abstract of Engineering Doctoral Dissertation.MGTU, Moscow (2001).

3. A. E. Polyakov et al, Khim. Volokna, No. 2, 24-27 (2008).4. V. A. Dubovitskii et al. Useful-Model Patent No. 110091 (10.11.2011). Unit for Controlling Lap Formation

and Winding.5. V. A. Dubovitskii and A. E. Polyakov, Khim. Volokna, No. 2, 41-44 (2011).