KR102734364B1 - Automatically calibration method the coordinates of a sewing machine - Google Patents

Abstract

The present invention relates to a method for automatically correcting coordinates of a sewing machine capable of automatically correcting a distortion of a trapezoidal shape of a straight line caused by an abnormality of an X-Y frame. The method comprises the steps of: (a) storing a plurality of ideal XY coordinates in a storage unit in an ideal state of an X-Y transfer frame that moves a sewing needle in an X-Y direction in a main central processing unit (CPU); (b) moving the X-Y transfer frame to the coordinates in a calibration mode where a pin is mounted on the X-Y transfer frame and a jig for distortion detection is set instead of an embroidery item, to obtain and store a plurality of measurement coordinates; (c) extracting four adjacent coordinates from the plurality of measurement coordinates and determining the distortion shape by calculating the extracted four coordinates; (d) judging that the intermediate position based on the coordinates is not located on a straight line between both ends, determining it as a curved distortion, and applying a correction algorithm for curved distortion to correct the distortion; and (e) storing a corrected design file in the storage unit.

Description

{Automatically calibration method the coordinates of a sewing machine}

The present invention relates to automatic coordinate correction of a sewing machine, and more particularly, to a method for automatic coordinate correction of a sewing machine which enables automatic correction of not only a trapezoidal straight-line distortion caused by an abnormality in an X-Y frame, but also a curved distortion caused when an X-Y transport frame is bent.

A sewing machine is a machine that performs repeated, easy-to-use mechanical movements to sew together pieces of fabric, and has been mainly used to make clothing and other daily necessities that are essential to human life.

As civilization developed and the population increased, sewing various items to make life more convenient and safe, including clothing, became necessary, and it became necessary to repeatedly produce items of the same design and size.

In particular, in order to mass-produce textile products of the same size and design, an electronic circuit control function was added to a mechanical sewing machine to automate the process, making it possible to mass-produce identical textile products of the same specified specifications. Such sewing machines are called electronically controlled automatic sewing machines or computer sewing machines.

Typically, an electronically controlled sewing machine includes a central control unit (main CPU), an operation and application program, a memory storing control data or programs, an input unit for inputting data and control commands, a display unit for outputting and displaying the status of automatic processing, and an image input unit for inputting or acquiring images or patterns.

In order to produce high-quality embroidery using an electronically controlled sewing machine, the electronically controlled sewing machine must always be kept in optimal condition.

Some parts of an actual electronically controlled sewing machine are made up of mechanical equipment, and with long-term use, mechanical equipment such as the X-Y transport frame that performs frequent movements usually experiences deformation such as bending or mechanical tolerances.

When deformation or mechanical tolerance of the transfer frame occurs, the methods to overcome this include replacing it with new equipment or using it after correcting the coordinate distortion.

Since replacing with new equipment is a burden on the business side, most companies mainly use a method of producing high-quality embroidery through coordinate distortion correction.

A method for correcting the coordinate distortion of an electronically controlled sewing machine is to attach a test pin to the needle bar instead of a sewing needle, attach a jig for coordinate measurement instead of the sewing material, slowly lower the needle bar, and then analyze the measured coordinate values to perform correction.

For example, for the calibration of an electronically controlled sewing machine, as illustrated in Fig. 1, each coordinate value is measured based on 9 holes of n coordinates. Here, the method of performing calibration using the coordinate values of 9 holes is an example, and it will be obvious to those skilled in the art to perform calibration using coordinate values of fewer holes or using more coordinate values.

When a touch command of a specific coordinate (e.g., n1) is input using an input means, the main control unit operates the motor drive unit to move the XY motors to the preset coordinates (e.g., X-290, Y+190) and move the X-Y transfer frame to the corresponding position. Then, when the X-Y transfer frame has completed moving to the corresponding position, the main control unit operates the spindle motor to slowly lower the needle bar so that the pin touches the jig. Then, the coordinate values of the touched jig are read and stored as the measurement values of the corresponding coordinates and displayed on the screen through the display unit. The user (corrector) recognizes the direction in which the pin is offset through the values of the corresponding coordinates through the display unit, and adjusts the X and Y values to be corrected using the arrow keys to correct so that the pin is located at the center of the coordinates. Here, the operation of the arrow keys is in the form of moving 0.05 mm per 1 PULSE. In other words, if the arrow keys are operated once, it moves 0.05 mm. Through this process, when the pin is located at the center of the coordinates, press the Enter key to end the calibration for the n1 coordinate. This method is repeated to perform calibration for the n2 to n9 coordinates.

However, this manual XY coordinate calibration method requires a lot of calibration time and has the disadvantage of lacking accuracy due to user intervention.

Therefore, recently, the method of automatic XY calibration using image conversion method is mainly used.

Figure 2 is an example of performing XY calibration by perspective transforming an original image, or performing XY calibration by affine transforming (translating, translating, resizing, rotating, and symmetrically transforming) an original image. Here, perspective transform refers to a geometric transformation method of an image using a determinant. In other words, the original image is geometrically transformed into a trapezoidal shape through perspective transform or affine transform, and the determinant thus geometrically transformed is processed with a preset correction algorithm to correct the XY coordinates, thereby modifying the design file and performing sewing.

Figures 3 and 4 are exemplary diagrams for explaining an XY calibration method using conventional image conversion.

As shown in Fig. 3, the XY coordinates of the XY position command value are stored. The XY coordinates are stored by performing five measurements. Here, the XY coordinate values are ideal coordinate information. If this is expressed as a formula, it is as shown in [Mathematical Formula 1] below.

여기서 x_i = i번째 재봉침 CAD/CAM 재봉 좌표 x축 위치 명령값, y_i = i번째 재봉침 CAD/CAM 재봉 좌표 y축 위치 명령값,

= i번째 재봉침 CAD/CAM 재봉 좌표 x축 위치 명령 제어 결과값,

= i번째 재봉침 CAD/CAM 재봉 좌표 y축 위치 명령 제어 결과값,

= i번째 재봉침 CAD/CAM 재봉 좌표 (x,y)축 위치 명령 제어 결과값이다.

Here, x _i = i-th sewing needle CAD/CAM sewing coordinate x-axis position command value, y _i = i-th sewing needle CAD/CAM sewing coordinate y-axis position command value,

= i-th sewing needle CAD/CAM sewing coordinate x-axis position command control result value,

= i-th sewing needle CAD/CAM sewing coordinate y-axis position command control result value,

= It is the result of the command control for the position of the i-th sewing needle CAD/CAM sewing coordinate (x,y) axis.

Next, the XY position is measured using a pin and a jig, and the measured coordinate information is stored. Five measurements are performed to store the XY coordinates. Here, the XY coordinate values are actual measured coordinate values, and may include distortion as shown in Fig. 4. Here, the distortion may occur due to deformation or tolerance of the X-Y transfer frame. If this is expressed in a formula, it is as shown in [Mathematical Formula 2] below.

를 아래의 [수학식 3]에 대입하여, 좌표 p11부터 좌표 p33을 계산한다.Next, through the above process,

By substituting into [Mathematical Formula 3] below, coordinates p11 to p33 are calculated.

Through this process, the XY coordinates of the design file to be sewn are corrected based on the corrected XY coordinates, and the corrected design file is then stored in the storage unit. This XY coordinate calibration is performed every time the calibration mode is executed, and the design file is corrected by correcting the XY coordinates of the design file with the XY correction coordinates according to the performance result.

The main central processing unit (Main CPU) extracts the corrected design file stored in the storage unit and performs sewing, thereby correcting the straight line distortion of the XY transport frame caused by deformation or tolerance of the X-Y frame, thereby producing a precise embroidery.

However, this XY calibration method using perspective transformation has a disadvantage in that, due to the characteristics of perspective transformation, it can only correct XY frame distortion for a trapezoid with straight upper, lower, and side surfaces, as shown in Fig. 4, and cannot correct curved distortion that occurs when the X-Y translation frame is bent.

Therefore, a calibration technology that can correct both linear and curved distortions caused by bending or tolerance of the XY transport frame is required.

Korean Patent No. 10-0407698 (registered on November 19, 2003) (control device and control method for a shape sewing machine) Republic of Korea Publication Patent No. 10-2012-0119282 (Published on October 31, 2012) (Embroidery machine and its correction method) Republic of Korea Patent No. 10-2044682 (registered on November 8, 2019) (Method for correcting design coordinates of a sewing machine) Korean Patent No. 10-25090407 (registered on 2023.03.08) (Sewing system using barcode recognition for pattern sewing machine and sewing method using the same) Japanese Patent Publication No. 2018-68722 (Published on May 10, 2018) (Missing machine and retaining member) US Patent 10,619,278 (registered on April 14, 2020) (Method of sewing a fabric piece onto another fabric piece based on image detection)

Accordingly, the present invention has been proposed to solve the disadvantage of being unable to correct curved distortions that occur in the above-described general computer sewing machines and in the prior art X-Y transport frame distortion correction methods, and the purpose of the present invention is to provide an automatic coordinate correction method for a sewing machine that enables automatic correction of not only trapezoidal straight-line distortions that occur due to an abnormality in the X-Y frame, but also curved distortions that occur when the X-Y transport frame is bent.

In order to achieve the above-mentioned purpose, the "automatic coordinate correction method of a sewing machine" according to the present invention,

(a) a step of storing a plurality of ideal XY coordinates in an ideal state of an X-Y transport frame that moves a sewing needle in the X-Y direction;

(b) a step of mounting a pin on the X-Y transfer frame in a calibration mode, mounting a jig for distortion detection instead of embroidery, moving the X-Y transfer frame to a coordinate to obtain and store a plurality of measurement coordinates;

(c) a step of determining a distortion shape based on arbitrary multiple coordinate values from the multiple measurement coordinates;

(d) a step of correcting the distortion by applying a trapezoidal distortion correction algorithm when the distortion type determined in step (c) is a straight-line distortion of a trapezoidal shape;

(e) a step of correcting the distortion by applying a curve-shaped distortion correction algorithm when the distortion type determined in step (c) is a curve-shaped distortion;

(f) a step of correcting the XY coordinates of the design file to be sewn with the XY coordinate correction values corrected in step (d) or step (e), and then storing the corrected design file in the storage unit; and

(g) It is characterized by including a step of controlling sewing in the main central processing unit based on the corrected design file stored in the above storage unit.

The measurement coordinates of step (b) above are characterized as coordinates that include distortion information in the form of a straight line or a curve.

Step (c) above is characterized by extracting four adjacent coordinates from the plurality of measurement coordinates and calculating the four extracted coordinates to determine the distortion shape.

According to the present invention, not only is it possible to correct a trapezoidal straight-line distortion caused by an abnormality in the X-Y frame, but it is also possible to automatically correct a curved distortion caused when the X-Y transport frame is bent, thereby having the effect of always helping to produce high-quality embroidery.

Figure 1 is an example diagram explaining the calibration method of a general computer sewing machine.
Figure 2 is an example of an image transformation that performs XY calibration using conventional perspective transformation.
Figure 3 is an example of coordinates of ideal XY position command values among conventional XY calibration methods.
Figure 4 is an example showing coordinate distortion in the form of a conventional straight line.
Figure 5 is a configuration diagram of a calibration system of a sewing machine to which the coordinate automatic correction method of a sewing machine according to the present invention is applied.
Figure 6 is a flow chart showing a method for automatically correcting coordinates of a sewing machine according to the present invention.
Figure 7 is an example of an ideal XY coordinate diagram when the mechanical assembly of the sewing machine in the present invention is ideal.
Figure 8 is an example showing a linear coordinate distortion in the present invention.
Figure 9 is an example showing a curved coordinate distortion caused by the bending phenomenon of the XY transfer frame in the present invention.
Figure 10 is an explanatory diagram explaining the linear coordinate distortion in the present invention.
Figure 11 is an explanatory diagram explaining the curved coordinate distortion in the present invention.

Hereinafter, a method for automatically correcting coordinates of a sewing machine according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

The terms or words used in the present invention described below should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best way.

Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

FIG. 5 is a block diagram of a coordinate calibration system (100) of a sewing machine to which an automatic coordinate correction method of a sewing machine according to a preferred embodiment of the present invention is applied, which may include an image acquisition unit (103) for acquiring a design for sewing on an embroidery fabric, a communication unit (104) for receiving the design data via a communication network, an input unit (101) for setting a function, inputting an operation command, setting a calibration mode, or inputting a coordinate measurement command or coordinate information, and a storage unit (102) for storing a calibration algorithm and ideal XY coordinate information. Here, the calibration algorithm may include a trapezoidal distortion correction algorithm for correcting trapezoidal distortion in a straight line shape and a curved distortion correction algorithm for correcting curved distortion.

In addition, the coordinate calibration system of the sewing machine may include a display unit (105) that displays coordinate information, distortion information, design pattern information, etc. on the screen, a main central processing unit (CPU) (106) that automatically corrects distortion in calibration mode and controls the X-Y feed motor and spindle feed according to the corrected design file, a motor drive unit (107) that drives the spindle motor (108) that moves the needle bar up and down according to the control of the main central processing unit (106) and drives the XY motor (109) that moves the X-Y feed frame in the XY axis direction.

The above main central processing unit (106) may include a distortion correction module that corrects linear distortion or curved distortion in calibration mode.

In the present invention, the sewing machine means an electronically controlled automatic sewing machine or a computer sewing machine, and the sewing machine hereinafter is understood to mean an electronically controlled automatic sewing machine or a computer sewing machine.

FIG. 6 is a flow chart showing the "Method for Automatic Coordinate Correction of a Sewing Machine" according to the present invention, and is a process for calibrating coordinates by software in the main central processing unit (CPU) of FIG. 5, comprising: (a) a step of storing a plurality of ideal XY coordinates in an ideal state of an X-Y transfer frame that moves a sewing needle in the X-Y direction (S101), (b) a step of moving the X-Y transfer frame in a calibration mode by mounting a pin on the X-Y transfer frame and mounting a jig for distortion detection instead of an embroidery fabric, and obtaining and storing a plurality of measurement coordinates (S102 to S103), (c) a step of determining a distortion type based on arbitrary multiple coordinate values from the plurality of measurement coordinates (S104), (d) a step of correcting the distortion by applying a trapezoidal distortion correction algorithm when the distortion type determined in step (c) is a trapezoidal straight-line distortion, (S105 to S106), (e) a step of correcting the distortion when the distortion type determined in step (c) is a curved-shaped distortion, The method may include a step of correcting distortion by applying a distortion correction algorithm (S107, S109); a step of terminating calibration if there is no distortion as a result of the judgment in step (c), (S108); (f) a step of correcting XY coordinates of a design file to be sewn with the XY coordinate correction values corrected in step (d) or (e) and then storing the corrected design file in a storage unit (S110); and (g) a step of controlling sewing in a main central processing unit based on the corrected design file stored in the storage unit (S111).

The measurement coordinates of the above step (b) may be coordinates that include distortion information in the form of a straight line or a curve.

The above step (c) extracts four adjacent coordinates from the plurality of measurement coordinates, and calculates the four extracted coordinates to determine the distortion shape.

The “automatic coordinate correction method of a sewing machine” according to the present invention configured as described above will be described in detail with reference to the attached drawings, FIGS. 5 to 11.

First, the main central processing unit (106) stores image information acquired through the image acquisition unit (103) or design files to be sewn on embroidery acquired through the communication unit (104) in the storage unit (102). In addition, ideal XY coordinate information to be used in the calibration mode is also input through the communication unit (104) or input unit (101) and stored in the storage unit (102) (S101).

Here, the ideal XY coordinate information is the XY coordinate information obtained in an ideal state by the mechanical assembly of the X-Y transport frame that moves the sewing needle in the X-Y direction.

As illustrated in Fig. 7, when the mechanical assembly state of the X-Y transport frame is in an ideal state (a state without distortion), nine ideal coordinates are stored, and this can be expressed mathematically as shown in [Mathematical Formula 4]. Here, the method of using nine ideal coordinates is only one embodiment, and the present invention is not limited thereto, and it will be apparent to those skilled in the art that a smaller number of coordinates or a larger number of coordinates can be used.

Thereafter, the function input through the input unit (101) is checked, and if the input function is a sewing function, the design file stored in the storage unit (102) is extracted in the same manner as before, and the motor drive unit (107) is controlled based on the extracted design file, thereby controlling the main shaft motor (108) and the XY motor (109) to sew the design on the embroidery.

Meanwhile, if the function input through the input unit (101) is determined to be in calibration mode (S102), the X-Y transfer frame is moved to the coordinates to obtain multiple measured coordinates and store them in the storage unit (102) (S103).

Here, the calibration mode is a mode in which actual coordinate information is measured by contacting the corresponding coordinates according to the coordinate command while mounting a pin instead of a needle on the X-Y transfer frame and a jig for distortion detection instead of embroidery.

As shown in FIGS. 8 and 9, the X-Y transfer frame is moved in response to the coordinate command to store nine XY coordinates through actual measurement. Here, the XY coordinates are coordinates of a position corresponding to the position of the ideal XY coordinates, and if expressed as a mathematical formula, it is as follows: [Mathematical Formula 5].

The nine XY coordinates acquired through the above measurement may be coordinates that include information on straight-line distortion (Fig. 8) or curved distortion (Fig. 9) caused by an abnormal condition, tolerance, or bending phenomenon of the X-Y transport frame.

Next, the distortion shape is determined based on arbitrary multiple coordinate values from the multiple measurement coordinates (S104). That is, four adjacent coordinates (e.g., p ₁₁ , p ₁₂ , p ₂₁ , p ₂₂ ) are extracted from the multiple measurement coordinates, and the distortion shape can be determined by calculating the four extracted coordinates.

That is, the distortion type is determined by comparing the four position values with each other.

In general, even if the position of the X-Y transfer frame is misaligned, both ends are located on a straight line as shown in Fig. 10, and the four position values are compared with each other, and if both ends are located on a straight line, it is judged that there is a distortion in the form of a straight line.

In contrast, if the X-Y transport frame is deformed, such as by bending, as shown in Fig. 11, the middle position is not located on a straight line at both ends, and in this case, it is judged to be a curved distortion.

Of course, if the four measured position values are identical to the ideal XY position coordinates, it is judged that no distortion occurs.

If the above judgment result shows that there is no distortion, calibration is terminated (S108).

In contrast, if the distortion type is a trapezoidal straight-line distortion as shown in Fig. 8 as a result of determining the above distortion type, the distortion is corrected by applying the trapezoidal distortion correction algorithm stored in the storage unit (102) (S105 - S106). Here, the trapezoidal distortion correction algorithm is the same as the aforementioned [Mathematical Formula 3], and the trapezoidal distortion in the straight-line shape is corrected by using it.

In addition, as a result of determining the above distortion type, if the distortion type is a curved distortion as in Fig. 9, the trapezoidal distortion correction algorithm stored in the storage unit (102) is applied to correct the distortion (S107, S109). If this is expressed as a mathematical formula, it can be expressed as in [Mathematical Formula 6] below.

여기서

= i번째 재봉침 CAD/CAM 재봉 좌표 x축 위치 명령값,

= i번째 재봉침 CAD/CAM 재봉 좌표 y축 위치 명령값,

= i번째 재봉침 CAD/CAM 재봉 좌표 (x,y)축 위치 명령 제어 결과값,

= CAD/CAM 재봉 좌표 명령값과 실제 제어된 결과 값 사이의 곡선 관계를 고려한 관계 매개 변수, p = CAD/CAM 재봉 좌표 명령값과 실제 제어된 결과값 사이 관계 매개 행렬이다.

Here

= i-th sewing needle CAD/CAM sewing coordinate x-axis position command value,

= i-th sewing needle CAD/CAM sewing coordinate y-axis position command value,

= i-th sewing needle CAD/CAM sewing coordinate (x,y) axis position command control result value,

= Relationship parameter considering the curvilinear relationship between the CAD/CAM sewing coordinate command value and the actual controlled result value, p = Relationship parameter matrix between the CAD/CAM sewing coordinate command value and the actual controlled result value.

Here, the front end is a distorted position value, and the rear end is an ideal XY coordinate value. These are substituted into the above [Mathematical Formula 6] to calculate the correction value for each coordinate.

The process of calculating the correction value for each coordinate is described in detail as follows.

If the 9 coordinates for the above [Mathematical Formula 6] are expressed as [Mathematical Formula 7] below,

The coordinate correction calculation is as follows:

If we simply express the above [Mathematical Formula 7], can be expressed as

Next, compute Z ^T on both sides ( ) is done.

Next, on both sides Each of them is calculated ( ).

By organizing the above formula, the parameter (P) is derived as follows ( ).

Through this process, calculations are performed from p ₁₁ to p ₃₅ to derive correction parameters (XY coordinate correction values) for each location.

Next, the XY coordinates of the design file to be sewn, stored in the storage unit (102), are automatically corrected with the XY coordinate correction values corrected in the step S106 or the step S109, and then the corrected design file is stored in the storage unit (102) (S110).

After the calibration process is completed and a sewing command is input, the main central processing unit (106) controls the motor drive unit (107) based on the corrected design file stored in the storage unit (102) to sew the embroidery (S111).

By using the trapezoidal distortion correction algorithm for correcting straight-line distortion and the curved distortion correction algorithm for correcting curved distortion, automatic calibration is possible even when curved distortion occurs due to the X-Y transfer frame being tilted or bent along the X-axis, so that the best embroidery can always be produced.

According to the present invention described above, not only is it possible to correct the trapezoidal straight-line distortion caused by an abnormality in the X-Y frame, but it is also possible to automatically correct the curved distortion caused when the X-Y transport frame is bent, thereby helping to always produce high-quality embroidery.

Although the invention made by the present inventor has been specifically described according to the above embodiments, it is obvious to a person skilled in the art that the present invention is not limited to the above embodiments and various modifications can be made without departing from the spirit thereof.

100: Coordinate Calibration System for Sewing Machines
101: Input section
102: Storage
103: Image acquisition section
104: Communications Department
105: Display section
106: Main CPU
107: Motor drive unit
108: Spindle Motor
109: XY motor

Claims (5)

(a) a step of storing a plurality of ideal XY coordinates in an ideal state of an XY transport frame that moves a sewing needle in the XY direction in a storage unit in a main central processing unit (CPU) that controls calibration and sewing;
(b) a step of moving the XY translation frame to coordinates in a calibration mode in which a pin is mounted on the XY translation frame and a jig for distortion detection is placed instead of an embroidery material, thereby obtaining and storing a plurality of measurement coordinates;
(c) a step of extracting four adjacent coordinates from the plurality of measurement coordinates and calculating the four extracted coordinates to determine the distortion shape;
(d) a step of judging the distortion type in step (c) above, if the middle position based on the coordinates is not located on a straight line at both ends, judging it as a curved distortion, and applying a curved distortion correction algorithm to correct the distortion; and
(e) a step of correcting the XY coordinates of the design file to be sewn with the XY coordinate correction values corrected in step (d) above, and then storing the corrected design file in a storage unit;
The algorithm for correcting curve-shaped distortion of the above step (d) is a method for automatically correcting coordinates of a sewing machine, characterized in that it corrects curve-shaped distortion using the following formula.

Here

= i-th sewing needle CAD/CAM sewing coordinate x-axis position command value,

= i-th sewing needle CAD/CAM sewing coordinate y-axis position command value,

= i-th sewing needle CAD/CAM sewing coordinate (x,y) axis position command control result value,

= Relationship parameter considering the curvilinear relationship between the CAD/CAM sewing coordinate command value and the actual controlled result value, p = Relationship parameter matrix between the CAD/CAM sewing coordinate command value and the actual controlled result value, where the front end is the distorted position value and the back end represents the ideal XY coordinate value.
A method for automatically correcting coordinates of a sewing machine, characterized in that in claim 1, the measurement coordinates of step (b) are coordinates that include distortion information in a straight line shape or a curved shape.



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