Title of Invention

A SYSTEM FOR DETECTION, OF YARN FAULTS, AND ON-LINE CLEARING AND IDENTIFICATION OF THE SHAPE OF THE FAULTS

Abstract

ABSTRACT A system for detection of yarn fault and a system for online clearing of yarn fault by fault signal frequency analysis using FFT (Fast Fourier Transformation) functions. A system for detection of yarn faults including means for sensing the yarn thickness, means for converting the sensed yarn signal to voltage/current signals with varying amplitudes, means for converting the voltage/current signals to digital signals, means for generating FFT based on said digital signals including means for analyzing of the FFT data, and means for detecting the yarn fault based upon said FFT analysis. The system also provides for on-line removal of thick fault and/or trimming hairiness of the yarn by use of an FFT based yarn fault clearing means. The system is directed to provide for more precise yarn fault detection as compared to conventional system of fault detection. It would also provide flexibility to isolate only those faults which need to be removed without unnecessarily affecting the other fault free areas. Such system using FFT (Fast Fourier Transformation) is simple and reliable for detecting fault and on-line clearing of the yarn fault. To The Controller of Patents The Patent Office At Cehnnai.

Full Text

Field of the invention The present invention relates to a system for yarn fault detection and system for on-line clearing of yarn faults. In particular, the invention relates to a system for yarn fault detection by fault signal frequency analysis and a system for clearing of the thick faults and/or trimming the hairiness of yarn. Background of the invention Faults in the yarn, thick and thin places, interfere with the subsequent processes of weaving and also affect the final fabric by appearance. Hence it is necessary to identify these faults by their length and the size and eliminate the faults which are objectionable. In the presently known systems, fault identification is done by integrating the continuous equivalent electrical signals and comparing with set peak signals. This type of classification and elimination of faults have to be achieved through a clearing curve. The set pattern of the curve provides very little flexibility to precisely remove the unwanted faults. The curve setting to remove one set of faults sometime results in removal of less objectionable faults because of the fixed nature of the curve. Objects of the invention It is thus the basic objective of the present invention to provide a system for fault detection which would provide for more precise yarn fault detection as compared to conventional systems of fault detection. Another object of the present invention is to provide for a system for yarn fault detection which would provide flexibility to isolate only those faults which need to be removed without unnecessarily affecting the other fault free areas. Yet another object of the present invention is to provide a simple and reliable system for fault detection by fault signal frequency using FFT (Fast Fourier Transformation) functions. Yet further object of the present invention is to provide a system for on-line clearing of yarn faults in particular, thick faults and/or thmming the hairiness of yarn thereby providing for uniform quality maintenance of yarn and improve productivity. Yet further object of the present invention is to provide for system of shape detection of yarn faults thereby providing for more precise elimination of the fault. Summary of the invention Thus according to one aspect of the present invention there is provided a system for detection of yarn faults comprising : means for sensing the yarn thickness ; means for converting the sensed yarn signal to voltage/current signals with varying amplitudes ; means for converting the voltage/current signals to digital signals ; means for generating FFT based on said digital signals including means for analyzing of the FFT data ; and means for detecting the yarn fault based upon said FFT analysis. The system of the invention thus detects the thick and thin place faults by determining the fault signal frequency using the FFT (FAST FOURIER TRANSFORMATION) functions. In the above disclosed system of the invention the means for sensing the yarn thickness comprise sensor means for sensing the thickness of the yarn and generate electrical equivalent by means of mass or by means of the shadow it forms or by any other means of thickness measurement. The measuring means can be either capacitance based or optical based. The means for converting the sensed yarn thickness into voltage/current signal is preferably an integral part of the thickness sensor itself. This assures that sensed thickness information is available in voltage or current variation. This can be achieved in vanous ways depending on the sensor used. The means for converting sensed voltage/current signal to digital signals convert the electrical equivalent signal of yarn thickness into digital data format. Such A/D converters can have any of accepted configurations such as single slope, successive approximation, dual slope, integrating type, flash ADC. Any such suitable technology based analog to digital converter can be used for this purpose. The means for generating FFT data can comprise a digital signal processing circuitry preferably comprising a central processing unit such as a Digital Signal Processor itself, along with all necessary components like random access memories (RAM), read only memories (ROM), logic selection components. The ROMs can contain all necessary software in assembly language programs for executing the step by step activities required to generate the FFT (Fast Fourier Transform) from the available yarn fault signal converted to digital data. In accordance with another aspect of the present invention the same provides a system for on-line clearing of yarn faults comprising : means for on-line removal of thick faults and/or trimming the hairiness of the yarn. If the yarn need to be cut after successful detection of a fault then the FFT based yarn fault detection circuitry is also provided with necessary logic and signal amplifier to generate a cut signal and to activate a cutter. The above system for on-line clearing of yarn faults can be used as an independent system or can be operatively connected to the system for measuring yarns thickness and detecting yarn faults. The above disclosed means for online removal of thick faults and/or trimming the hairiness of the yarn in accordance with the system of the invention can comprise use of laser beam of suitable power with necessary optical gadgets. Alternatively, such means for online removal of thick faults and/or trimming the hairiness of the yarn in accordance with the system of the invention can comprise cut generator circuitry with necessary logic operatively connected to the CCD array means to generate a cut signal and activate a cutter. The yarn cutter used can be a knife activated by magnet or any other type of yarn breaker which can do the breaking of yarn without adding tension on yarn and also which can break the yarn instantly after the detection of the fault. An yarn cutter amplifier can also be used in case the signal from the processor is yery weak and hence has to be suitably amplified to cut yarn. This can be a current amplifier or a voltage switch normally. Known electric gadgets may be used to active such amplification. The means for analyzing the CCD array image data comprise any conventional microprocessor having means to carry out diffraction equation calculations and fault detection cut generator by performing necessary logical operations depending upon yarn thickness and related parameters. For the purpose necessary software logic is built in the Read Only Memory content of the microprocessor. A Central Monitoring Station can be provided using a dedicated processor, shared processor or even with a PC dedicated for achieving or facilitating the above cut operations and/or trimming the hairiness. The above disclosed systems of the present invention comprising said system for detecting yarn faults and/or system for on-line clearing having means for removal of thick faults and/or trimming the hairiness of the yarn is operatively connected to a central monitoring station to provide for user interface, classification logic input and operatively connected to display unit/printer. The display system can be provided either in the circuit itself or at another control unit to which it will communicate by any suitable operative link. The central control unit is required to communicate the same settings by the user to all the FFT analyzer circuits and also to display the results at a single screen. The whole system should have a power supply which will be distributed or at each FFT analyzer end the single supply will be converted in to a number of essential voltages for the system to work perfectly. Since the yarn runs continuously at varying speed, there is preferably provided a cirucuit and/or logic to resolve the speed information and hence to sample the thickness at regular lengths of yarn. In accordance with yet further aspect of the present invention there is provided a system for detection of yarn fault and identify the shape of the fault comprising : means for A/D converting of yarn signal within specified time intervals ; means for comparing each sample with the specified levels to determine the occurrence of a fault; means for identifying fault condition data and means for continuously storing fault condition in a memory block and means for processing the fault amplitude wise and time wise to obtain a normalized waveform along time axis ; means for applying Fast Fourier Transform on the resulting wave generating the FFT outputs ; means for comparing FFT output with the store FFTs of classified fault shape signals ; means for weighing the compared results to identify the best match which is identified as the fault shape category. The above system of the invention provides for identifying the faults in the yarn, which are very precise and have greater flexibility to isolate only those faults which need to be removed, without unnecessarily getting into the other areas. The system of the invention works on the FREQUENCY domain instead of the earlier fault signal amplitude integration approach. Description of figures The systems of the invention are described hereunder in greater detail with reference to non-limiting exemplary embodiment in relation to the accompanying figure wherein : Fig.1 is a schematic illustration of the system for detection of yarn faults and on-line system for thick fault removal and/or trimming the hairiness of yarn. Fig. 2 is an illustration of categorized yarn faults under the system of the invention. Fig. 3 is an illustration of how the system of the invention provides for elimination of only the user defined faults alone without cutting any objectionable areas and without having any objectionable areas. Fig. 4 is an illustration of some typical fault shape. Description of preferred embodiments Reference is first invited to Fig. 1 which shows the system of detection of the yarn faults by means of a frequency domain analysis like FFT analysis and further classification of yarn fault by comparing the averaged time integral of the yarn fault signal amplitude with the user defined fault amplitude levels for the defined yarn fault length. The system illustrated in the figure shows schematically both the system for measurement and detection alongwith the system for on-line clearing of yarn faluts comprising means for removal of thick faults and/or trimming of hairiness of the yarn. The various means constituting such system of the invention and the mode of working of the system utilizing the various means are also illustrated by way of said figure. For the purpose of yarn fault removal in the system of the invention yarn faults of lengths from 1 mm to 32cm and above are classified. These faults generate electrical pulses of time width equal to the time for which it is present in the sensor area. At uniform yarn speed a short fault produce a short width pulse and a long fault produce a long width pulse. As the speed of the yarn increases, the time for which the fault is present at the sensor decreases and vice versa. Using this principle it is possible to detect the yarn faults at different speeds of the yarn winder. The system of the invention determines yarn faults at all speeds of the winding machine using a set of filters continuously varying their central frequencies in proportion to the winding speed. As illustrated of such categorisation of the yarn faults is provided in accompanying figure 2. The system also provides for elimination of the user defined faults alone without cutting any unobjectionable areas and without leaving any objectionable areas. This is explained in greater detail in relation to Fig. 3. Thus as distinct from the existing system of cut generation based on approximation, the system described here can detect fault signals in a wide range more accurately. The clearing curve separating the objectionable area and non-objectionable area are no more needed. It is now possible to directly specify what are the fault categories needed to be removed and what not. Fig. 3 shows the only possibility if the existing known system of clearing is used and if the system of the invention is used the clearing as shown in Fig. 3 can be achieved. The system of the invention further provides the possibility of characterizing a fault in terms of a third dimension describing the precise shape of the fault thereby allowing to retain certain faults while removing others within the same fault category characterized by the amplitude and length. Some typical fault shapes shown in Fig. 4 which are given below and which cannot normally be recognized as different from one another with existing systems, can be identified by this inventive method. The system of this invention also distinguish between different types of neps such as seed coat neps and others. All the present day clearer are based on the % thickness or thinness and it's length. However, many faults which will come in this category may not be removed if we are able to classify them according to the shape of the yarn fault. Some thick faults may not be as harmful as others if shape is considered, but the existing clearers will see it as an objectionable fault and remove the same by cutting the yarn. Thus the system for on-line clearing of the invention is advantageous being more accurate and user friendly. Advantageously in the system of the invention it is possible to use up to date chips which can read samples from A/D converters, store it temporarily and scale it, normalize it, do FFT, comparison etc. Such chips are known to be used for speech recognition and image recognition. The logic based sequence of operation can be varied depending upon end use and performance level required. The system of this invention can thus provide the precise identification and elimination of only the objectionable faults thereby enabling greater flexibility in the settings. Possible use of up to date technology chips further provide FFT analysis in less clock cycles, reducing the calculation time, high speeds, integration of more sensors into a single processing unit ultimately resulting in reduced hardware and thus cost effective. The system serves as a calibrated system which do not have any ambiguous area of fault and clearly indicates the objectionable fault as the detected fault and all other yarn signals as normal. We Claim : 1. A system for detection of yarn faults comprising : means for sensing the yarn thickness ; means for converting the sensed yarn signal to voltage/current signals with varying amplitudes ; means for converting the voltage/current signals to digital signals ; means for generating FFT based on said digital signals including means for analyzing of the FFT data ; and means for detecting the yarn fault based upon said FFT analysis. 2. A system for detection of yarn faults as claimed in claim 1 wherein said means for sensing the yarn thickness comprise sensor means for sensing the thickness of the yarn. 3. A system for detection of yarn faults as claimed in claim 2 wherein said sensor j means is adapted to generate electrical equivalent based on anyone or more of I mass variations, yarn image shadow and any other known means for measurement. ■ 4. A system for detection of yarn faults as claimed in anyone of claims 1 or 2 wherein said sensor means is capacitance based and/or optical based. 5. A system for detection of yarn faults as claimed in anyone of claims 1 to 3 wherein said means for converting the sensed yarn thickness into voltage/current electrical signal is an integral part of the thickness sensor itself. 6. A system for detection of yarn faults as claimed in anyone of claims 1 to 5 wherien said means for converting sensed voltage/current electrical signal to digital signals is adapted to convert the electrical equivalent signal of yarn thickness into digital data format. 7. A system for detection of yarn faults as claimed in anyone of claims 1 to 6 wherein said means for converting sensed voltage/current electrical signal to digital signals is A/D converter of any suitable configurations such as single slope, successive approximation, dual slope, integrating type, flash ADC. 8. A system for detection of yarn faults as claimed in anyone of claims 1 to 7 wherein said means for generating FFT data comprise a digital signal processing circuitry preferably comprising a central processing unit. 9. A system for detection of yarn faults as claimed in claim 8 wherein said central processing unit comprise Digital Signal Processor along with random access memories (RAM), read only memories (ROM), logic selection components and other conventional gadgets. 10. A system for detection of yarn faults as claimed in claim 9 wherein said ROMs means is adapted to generate the FFT (Fast Fourier Transform) from the available yarn fault signal converted to digital data. 11.A system for detection of yarn faults as claimed in anyone of claims 1 to 10 comprising: means for on-line removal of thick faults and/or trimming the hairiness of the yarn. 12. A system as claimed in claim 11 comprising: means for on-line removal of thick faults and/or trimming hairiness of the yarn comprising cut generator circuitry with necessary logic operatively connected to the sensor means to generate a cut signal and activate a cutter and wherein the said cutter can be a knife activated by magnet or any other type of yarn without adding tension on yarn and also which can break the yarn instantly after the detection of the fault. 13. A system as claimed in claim 11 wherein said FFT based yarn fault detection circuitry is provided with means to generate a cut signal and to activate a cutter. \A V ys^k system as claimed in anyone of claims i2^tevl4 wherein said means for on-line ^ clearing for removal of thick faults and/or trimming the hairiness of the yarn is operatively connected to a central monitoring station to provide for user interface, classification logic input and operatively connected to display unit/printer. y&:k system as claimed in claim J^wherien said display system is provided in the circuit itself or at another control unit to which it communicates by suitable operative link. \u\T.tK system as claimed in claim ;l^ wherein said central control unit communicate the same settings by the user to plurality of FFT analyzer circuits and display the results at one or more display means. ^^ >6. A system as claimed in claim IT'wherein a single power supply means is adapted to distribute to every FFT analyzer. . A system as claimed in claim J-B wherein independent power supply means are provided for each of the plurality of the FFT analyzer circuits., . A system as claimed in anyone of claims >2^to ^ comprising cirucuit and/or logic means to resolve the speed information and to sample the thickness at regular lengths of yarn. I ^. A system gs claimed in anyone of claims ^ to^ comprising means for detection of yarn fault and identification of the shape of the fault comprising : means for A/D converting of yarn signal within specified time intervals ; means for comparing each sample with the specified levels to determine the occurrence of a fault; means for identifying fault condition data and means for continuously storing fault condition in a memory block and means for processing the fault amplitude wise and time wise to obtain a normalized waveform along time axis ; means for applying Fast Fourier Transform on the resulting wave generating the FFT outputs ; means for comparing FFT output with the store FFTs of classified fault shape signals; means for weighing the compared results to identify the best match which is identified as the fault shape category. ' system as claimed in anyone of claims 1 to comprising chip means adapted to analyze A/D converter signals, store it and perform FFT and compare FFT signals to determine the nature/categories of the yarn fault. J23:A system for on-line detection of yarn faults, system for on-line clearing of yarn ' . fault and syotom for idontification of yaffl^^feigte substantially as herein described ad illustrated with reference to the accompanying figures.

Documents:

1017-mas-1999 abstract-duplicate.pdf

1017-mas-1999 abstract.pdf

1017-mas-1999 claims-duplicate.pdf

1017-mas-1999 claims.pdf

1017-mas-1999 correspondence-others.pdf

1017-mas-1999 correspondence-po.pdf

1017-mas-1999 description (complete)-duplicate.pdf

1017-mas-1999 description (complete).pdf

1017-mas-1999 drawings-duplicate.pdf

1017-mas-1999 drawings.pdf

1017-mas-1999 form-1.pdf

1017-mas-1999 form-19.pdf

1017-mas-1999 form-26.pdf

1017-mas-1999 form-3.pdf

1017-mas-1999 petition.pdf