Sewing system
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- JUKI CORP
- Filing Date
- 2017-09-15
- Publication Date
- 2026-06-11
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
TECHNICAL AREA
[0001] The present invention relates to a sewing system in which a robot arm is equipped with a sewing machine. BACKGROUND OF THE INVENTION
[0002] In the prior art, a sewing system is designed in which a front end region of a robot arm is equipped with a sewing machine and a sewing process is carried out on a curved surface which has a three-dimensional shape, without the sewing being limited to a flat surface.
[0003] If, at the start of sewing with this sewing system, the needle center position of the sewing machine, which is set in a coordinate system of the robot arm, and the actual needle center position of the mounted sewing machine do not precisely match each other, the sewing process cannot be carried out in the desired way, and an improvement in sewing quality cannot be achieved (see, for example, JP H05-305 193 A).
[0004] The needle center position of the sewing machine, which is set in the coordinate system of the robot arm, and the actual needle center position of the sewing machine coincide precisely when the sewing machine is precisely mounted on the robot arm; however, this requires a high degree of precision in the assembly work of the sewing machine and leads to a problem insofar as the load associated with the assembly work becomes very high.
[0005] US Patent 2015 / 0 234 375 A1 discloses a robot system and a method for correcting a tool coordinate system of a robot system. DE 10 2015 001 527 A1 describes a robot system that uses visual feedback. US Patent 2015 / 0 158 176 A1 deals with a machine equipped with an articulated robot and with a machine for assembling electrical components. US Patent 2015 / 0 258 688 A1 discloses a robot system, a calibration method for a robot system, and a position correction method for a robot system. US Patent 5 313 897 A describes a robot for performing sewing operations. CN Patent 1 05 447 856 A deals with methods for connecting marker points based on motion parameters and characteristic vectors of a robot.From JP 2015 - 89 607 A, a program for correcting tool tip information, a device for correcting tool tip information and a method for correcting tool tip information are known. SUMMARY OF THE INVENTION
[0006] The present invention aims to improve the sewing quality while reducing the stress, and has one of the following features (1) or (2).
[0007] (1) Sewing system, comprising: a sewing machine; a camera that captures an image of a reference position for sewing; a robotic arm that holds the sewing machine and the camera; and a control device, wherein The control unit controls the following operations: Forming an initial stitch position, which results from a stitch formation of the sewing machine; and Forming a second stitch position resulting from stitch formation by the sewing machine after the sewing machine has rotated at a prescribed angle around an axis of rotation which passes through a needle center position stored by the control device, and wherein The control unit further performs a calibration process which calibrates the needle center position stored by the control unit, based on each position of the first stitch position and the second stitch position within image acquisition areas of acquisition images obtained by capturing images of the first stitch position and the second stitch position using the camera.
[0008] (2) Sewing system according to (1), wherein the robot arm includes a first joint which causes the entire robot arm to rotate around an axis in a vertical upward and downward direction, wherein The control unit for a stub position, which is to be set as a target, controls the following operations: Forming a third stitch position using the sewing machine after a positioning operation resulting from a rotation in a fixed direction in the first joint, and Forming a fourth stitch position using the sewing machine after a positioning operation resulting from a rotation in a direction opposite to the fixed direction in the first joint; Capturing images of the third stitch position and the fourth stitch position using the camera; and Acquiring an amount of dead gait occurring in the first joint, based on each position of the third stitch position or the fourth stitch position within image acquisition areas.
[0009] According to the present invention, the control device can detect the actual needle center position of the sewing machine more precisely, and the stitch position of the sewing machine can be positioned more accurately by the robot arm, making it possible to improve the sewing quality without burdening the operator. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view showing an overall configuration of a sewing system according to an embodiment of the present invention; Fig. 2 is a side view showing a sewing machine in a state where a stitch plate is arranged in an upper position; Fig. 3 is a side view showing the sewing machine in a state where the stitch plate is in a lower position; Fig. 4 is a block diagram in a control system of the sewing system; Fig. 5 is a flowchart for calibration processing; Fig. 6 is an explanatory diagram showing capture images at the first and second stitch positions; Fig. Figure 7 is an enlarged explanatory diagram showing an arrangement of one needle center position and another needle center position on an XY plane; Fig. 8 is a flowchart for the acquisition processing of an amount of dead weight; and Fig. Figure 9 is an explanatory diagram showing the images captured at the third and fourth stitch positions. DETAILED DESCRIPTION: Overall configuration of the sewing system
[0010] In the following, a sewing system 100 according to an embodiment of the present invention is described with reference to the drawings. Fig. Figure 1 is a side view showing an overall configuration of the sewing system 100.
[0011] The sewing system 100 comprises a sewing machine 10, which performs a sewing operation on a workpiece, and a robot arm 110, which not only holds the sewing machine 10, but also positions the held sewing machine 10 with respect to the workpiece and performs any sewing operation, as well as a control device 90, which controls each of the component-forming components described above. robot arm
[0012] The robot arm 110 is a vertical-jointed robot arm comprising a base 111, which serves as a foundation, a plurality of arms 112, each connected via joints 113, a servo motor 114 as a drive power source provided in each of the joints 113, and an encoder 115, which detects each arm angle at which a rotation or drive is performed by each servo motor 114. The sewing machine 10 is held at a front end region of the plurality of arms 112, each connected via the joints 113.
[0013] Each of the joints 113 described above is formed with one of the joints, which are a pivot joint, which holds one end of the arm so that it can pivot and supports the other end on a wave bearing, and a rotation joint, which supports on a wave bearing so that the arm itself can rotate around the longitudinal direction of the arm.
[0014] The robot arm 110 comprises six joints 113 and can position the sewing machine 10 at the front end area of the joints in any position and assume any posture using six axes.
[0015] This makes it possible to induce the robot arm 110 to perform the sewing process along any curve on a three-dimensional surface of the workpiece.
[0016] The joint 113 closest to the base 111, which is positioned at the bottom of the robot arm 110, is defined as a first joint 113A. This first joint 113A can rotate the entire robot arm 110, except for the base 111, about an axis in a vertical upward and downward direction.
[0017] Without being limited to six shafts, the robot arm 110 can also use seven shafts, each with seven joints. In this case, the creation of a redundant joint allows the central joint to be set in motion while the sewing machine 10 is positioned and assumes any desired posture. This prevents any interference with other components in the vicinity of the robot arm 110. As a result, the sewing machine 10 can be positioned and assumed in any desired posture over a wider range of motion.
[0018] The front end region of the robot arm 110 holds an upper part of a front end region (a needle bar-side end region) of an arm region 23 in a sewing machine frame 20 of the sewing machine 10, and in this way a distance between the neighborhood of a stitch position of the sewing machine 10 and the front end region of the arm of the robot arm 110 can be reduced, and it is possible to position the stitch position more precisely. sewing machine
[0019] Fig. 2 and Fig. Figure 3 shows side views of sewing machine 10. As in Fig. 2 and Fig. As shown in Figure 3, sewing machine 10 has a stitch plate 13 and a base 61, which holds the needle plate 13, that can be raised and lowered relative to a bed area 21 of the sewing machine frame 20. Sewing is carried out in the raised positions of the stitch plate 13 and the base 61, which are in Fig. 2 are shown. An operation of preparing for sewing, such as placing the workpiece in a descending position, which is shown in Fig. The action shown in section 3 will be carried out.
[0020] The sewing machine 10 described above comprises a needle bar 12, which holds two sewing needles 11 at its lower end; a needle bar vertical movement mechanism, which enables the needle bar 12 to perform a vertical back-and-forth movement operation; a gripper mechanism, which causes a gripper thread to be inserted into a needle thread passing through each sewing needle 11 by means of two grippers; a lifting and lowering mechanism, which performs a lifting and lowering operation of the base 61, which holds the stitch plate 13 and a gripper; a presser foot 14, which presses the workpiece from above against the stitch plate 13 in the raised position; a camera 15 as an image capture device, which captures an image of a reference line formed on the workpiece; and a laser 16 as a light source, which emits slit light for suitable execution of the image capture of the reference line towards the workpiece.and the sewing machine frame 20, which holds each of the component parts described above.
[0021] The sewing machine frame 20 comprises the bed area 21, which extends in a predetermined longitudinal direction, an upright stand area 22, which is provided upright in a direction extending from an end area of the bed area 21 in a direction orthogonal to a longitudinal direction of the bed area 21, and the arm area 23, which extends from a head area of the upright stand area 22 in the same direction as the bed area 21.
[0022] In the following description of each of the constituent components of the sewing machine 10, a longitudinal direction of the bed area 21 is defined as the Y-axis direction, a direction which runs orthogonal to the Y-axis direction and in which the upright stand area 22 is provided in the upright position is defined as the Z-axis direction, and a direction which runs orthogonal to the Y-axis direction and the Z-axis direction is defined as the X-axis direction.
[0023] One side of the Y-axis direction is defined as the front direction and the other side as the back direction. One side of the X-axis direction is defined as the left direction (towards the back of the sheet). Fig. 2) and the other side is the right direction (towards the front of the sheet) Fig. 2) defined. One side of the Z-axis direction is defined as an upward direction and the other side as a downward direction.
[0024] The needle bar vertical movement mechanism has a well-known configuration in which a top shaft is driven rotatably by a sewing machine motor 24 as a drive power source and in which the needle bar 12 is caused to move up and down via a crank mechanism.
[0025] An upper shaft of the needle bar vertical movement mechanism extends along the Y-axis direction within the arm area 23 and provides a torque to a lower shaft, which, via a belt mechanism not shown, drives the gripper mechanism.
[0026] The press foot 14 is held at a lower end region of a press rod 141 extending along the Z-axis direction, which is positioned adjacent to the left side of the needle bar 12, and provides a downward pressing force via the press rod 141 by means of a press spring (not shown).
[0027] A presser lifting mechanism (not shown) is provided together with the presser foot 14, and the presser foot 14 can be held in a retracted position, which is positioned higher when not sewing. The presser lifting mechanism can be operated manually; however, it is desirable that switching between the retracted position and a sewing position be possible according to a control signal using an actuator.
[0028] The gripper mechanism comprises two grippers, which are positioned below the needle plate in a manner corresponding to two sewing needles, a lower shaft through which torque from the sewing machine motor 24 is transmitted and which may be divided into two parts, and a cam mechanism that enables each gripper to perform a coupled back-and-forth movement operation. The two grippers and the cam mechanism are held by the base 61, which is described below.
[0029] In a state where two grippers are arranged side by side in the Y-axis direction, the tapered front end of each gripper is directed to the left, and the coupling causes the front end to dip into a loop of needle thread, which is then caused to pass through each stitch plate 13. Thus, the loop of needle thread is not only captured, but the gripper thread is also caused to be inserted. Retraction of the gripper causes a loop of gripper thread to form, and the sewing needle 11 dips into the loop of gripper thread to capture it. Repeating this process creates a seam.
[0030] It is possible that the lower shaft is divided into two parts, a front part and a rear part. The front part, together with the gripper and cam body mechanism, is rotatably mounted on the base 61.
[0031] The front part of the lower shaft provides torque to the cam mechanism. By means of a rotating cam, the cam mechanism enables a coupling arm, which holds the gripper, to perform the coupled back-and-forth movement operation.
[0032] As described above, a torque is transmitted from the upper shaft via the belt mechanism using the rear part of the lower shaft.
[0033] The front and rear portions of the lower shaft are typically arranged on the same axis and connected by an Oldham coupling. This allows the front and rear portions to rotate in a coupled manner. When the base 61 is lowered to separate the needle plate 13 from the sewing needle 11, the characteristics of the Oldham coupling cause the front portion to move in such a way that it slides relative to the rear portion of the lower shaft, thus not interfering with the raising and lowering operation of the base 61.
[0034] As long as torque transmission is possible when the front part and the rear part are on the same axis, and as long as relative separation between the front part and the rear part is possible, the lower shaft can use a coupling structure different from the Oldham coupling.
[0035] The lifting and lowering mechanism comprises the base 61, which holds the main components forming part, for example the needle plate 13 and the gripper mechanism, and the cam body mechanism, which causes the base 61 to be lifted and lowered.
[0036] As described above, the base 61 holds the stitch plate 13 at its upper end area and holds below the stitch plate 13 component parts of the gripper mechanism, which are different from the rear part of the lower shaft 33.
[0037] A right outer wall of the base 61 is fixedly equipped with a sliding rail running in the Z-axis direction; this is not shown. Sliding movement along the Z-axis direction is possible with a sliding block, with which an inner wall of the bed area 21 is equipped.
[0038] The cam mechanism is provided on a left outer wall of the base 61. The cam mechanism comprises a roller, acting as a cam-driven body and provided on the base 61; a grooved cam body, acting as a cam-driven body and provided on the sewing machine head side; and an air cylinder 62 as a drive power source, which allows the grooved cam body to perform a movement operation in the forward and reverse directions. The cam mechanism includes a cam groove that is diagonally formed in the forward and reverse directions and in the upward and downward directions.When the cam body mechanism is moved backwards and forwards by the air cylinder 62, the roller inside the cam body groove causes the base 61 to be moved in the upward and downward direction; in this way the operation of raising and lowering the base 61 is made possible.
[0039] The camera 15 is positioned at the bottom of the bed section 21 such that an optical axis runs parallel to the upward and downward direction of the sewing needle 11 and points downwards. In a state where the robot arm 110 is installed on a horizontal surface, a state in which the needle bar 12 is arranged parallel to the vertically upward and downward direction (in which the bed section 21 and the arm section 23 of the sewing machine frame 20 are parallel to each other) is defined as a reference position of the sewing machine 10. In the reference position, the optical axis of the camera 15 runs parallel to the upward and downward direction and points downwards.
[0040] The laser 16 is positioned at the bottom of the bed area 21, behind the camera 15, and emits the slit light, which is parallel to the X-axis direction, diagonally forward in a downward direction.
[0041] The reference line, which is attached to the workpiece, is formed in the form of a groove. The emission of the slit light in a direction that intersects the reference line causes a concavity to appear at a reference line position, and in this way an image of the reference line position can be clearly captured. The tilt angle of the optical axis of the laser 16 is well known. The control unit 90 can maintain a distance of the slit light in the Z-axis direction (the upward and downward directions) from the camera 15 to the workpiece, whose image is captured within an image acquisition area of the camera 15, according to a position in the Y-axis direction. Control system of the sewing system
[0042] The control unit 90 of the sewing system 100 comprises, as shown in Fig. 4 shown, a read-only memory (ROM) 92 in which a program for carrying out various types of processing or control operations relating to sewing is stored, a random access memory (RAM) 93 which serves as a work area for arithmetic operation processing, a rewritable non-volatile data memory 94 as a memory area in which various data and the like are stored, and a central processing unit (CPU) 91 which executes the program in the ROM 92.
[0043] The CPU 91 controls the drive of the servomotor 114 of the robot arm 110 and the sewing machine motor 24 of the sewing machine 10 via motor drive circuits 114a and 24a. The encoder 115 and an encoder 25, which detect output axis angles, are provided together with the servomotor 114 and the sewing machine motor 24, respectively. The CPU 91 is connected via each of the detection circuits 115a and 25a. The robot arm 110 includes the servomotor 114 and the encoder 115 for each of the six joints 113 (including 113A); in Fig. However, only one servomotor 114 and one encoder 115 are shown in Figure 4, and representations of the other servomotors and encoders are omitted.
[0044] The CPU 91 is connected to a drive circuit 62a for controlling an electromagnetic valve 62b, which operates the air cylinder 62 that performs the operation of raising and lowering the base 61 of the sewing machine 10. The CPU 91 is connected to the camera 15 via an image processing unit 15a. The CPU 91 is connected to the laser 16 via a drive circuit 16a. Calibration processing of the sewing system
[0045] In order for the robot arm 110 to position the stitch position of the sewing machine 10 with high precision, it is necessary that position coordinates (a needle center position and a direction of the sewing machine 10 relative to the front end region of the robot arm 110) of a needle center position of the sewing machine 10 in a coordinate system (which is assumed to be a front end coordinate system) which is fixed at the front end region of the robot arm 110, are precisely acquired by the control unit 90.
[0046] In a case where the sewing machine 10 is mounted on the front end region of the robot arm 110, it is possible that the sewing machine 10 knows a relative positional relationship between a position held in the robot arm 110 and the needle center position based on design data, but because an error in assembly and the like also occurs, it is difficult to always precisely acquire the positional coordinates of the needle center position of the sewing machine 10 in the front end coordinate system of the robot arm 110.
[0047] Accordingly, the control unit 90 performs a calibration process, which is described below.
[0048] The "needle center position" of sewing machine 10 specifies the midpoint (the midpoint between the positions of two sewing needles 11 when viewed from above) between the positions of two sewing needles 11 on an XY plane. In a case where the sewing machine 10 is a single-needle sewing machine, the "needle center position" of the sewing machine specifies a position (a position of a sewing needle 11 when viewed from above) of a sewing needle 11 on the XY plane.
[0049] Fig. Figure 5 is a flowchart for the calibration processing, which is performed by the CPU 91 of the control unit 90 based on the program.
[0050] First, the CPU 91 performs a processing operation in which XY coordinate data, which specifies a pre-calibration needle center position, is read from the data memory 94 (step S1).
[0051] The data concerning the pre-calibration needle center position is, for example, a default value obtained from the design data of sewing machine 10, or a needle center position acquired in the previously performed calibration process.
[0052] Next, the CPU 91 causes the servomotor 114 of each of the robot arms 110 to transport the sewing machine 10 to a prescribed stitch position (step S3).
[0053] In the prescribed stitching position, a workpiece or holding device is installed which, in the event of a stitch being performed, is easily recognizable from a captured image of the stitching position. For example, a hole formed as a result of the stitch stands out from the image; however, a sheet of white paper or the like is also suitable.
[0054] Next, the CPU 91 initiates the drive of the sewing machine motor 24, thus executing the first stitch to establish an initial stitch position (step S5). At this point, the sewing machine 10 maintains the reference position, in which one longitudinal direction (the up and down direction of the needle) of the needle bar 12 is parallel to the vertical up and down direction.
[0055] Next, the CPU 91 causes the servomotor 114 of each of the robot arms 110 to be driven, and thereby causes - based on the data concerning the pre-calibration needle center position - the sewing machine 10 to perform a 90° rotation about a rotation axis along the vertical upward and downward direction passing through the center position in a counterclockwise direction (step S7).
[0056] This rotation operation is performed to maintain the needle center position (a preconfigured needle center position stored in the control unit 90) of the sewing machine 10 in an absolute coordinate system (a coordinate system that is fixed independently of the operation of the robot arm 110, with the floor serving as the reference).
[0057] A direction of rotation of the sewing machine 10 can be a clockwise direction, and it is possible to change a rotation angle to any angle without being limited to 90° (but an angle of 360° or an angle that is an integer multiple of 360°).
[0058] The sewing machine motor 24 is driven and the second stitch is executed to form a second stitch position (step S9).
[0059] Next, the CPU 91 causes the servomotor 114 of each of the robot arms 110 to be driven so that both first and second stitch positions also fall within an image capture area of the camera 15, and thus causes the sewing machine 10 to be moved so that the camera 15 can capture images of the first and second stitch positions (step S11).
[0060] Fig. Figure 6 is an explanatory diagram showing images of the first and second stitch positions.
[0061] An image processing unit 15a performs pattern matching and similar operations based on the captured image and extracts the first and second stitch positions. The CPU 91 calculates the actual needle center position of the sewing machine 10.
[0062] This means that the CPU 91 specifies a needle center position c1, which is the midpoint between first stitch positions p11 and p12, from the first stitch positions p11 and p12 resulting from the extracted first two sewing needles 11. In the same way, a needle center position c2, which is the midpoint between second stitch positions p21 and p22, is specified from the second stitch positions p21 and p22 resulting from the second two sewing needles 11.
[0063] The first stitch positions p11 and p12, the second stitch positions p21 and p22 and the needle center positions c1 and c2 are positions in the absolute coordinate system.
[0064] Fig. Figure 7 is an explanatory diagram showing an arrangement of the needle center position c1 and the needle center position c2 on the XY plane (a horizontal surface).
[0065] If the pre-calibration needle center position (a position in the front end coordinate system) stored in the control unit 90 is precise, then even if the sewing machine 10 is made to rotate by 90°, there will be no change in the position of the needle center position c1 and the needle center position c2 in the absolute coordinate system; however, if the pre-calibration needle center position contains an error, the position of the needle center position c1 and the needle center position c2 will change.
[0066] As in Fig. As shown in Figure 7, in the case of a positional discrepancy between the needle center position c1 and the needle center position c2 in the absolute coordinate system, the CPU 91 receives an arc-shaped vector b with a central angle of 90°, which is directed counterclockwise and is able to connect these points c1 and c2, and calculates a central position c0 of the arc-shaped vector b.
[0067] Since the control device 90 causes a rotation of the sewing machine 10 around this central position c0 (central position c0 = pre-calibration needle central position), this is compensated to obtain a correct position.
[0068] In particular, a value resulting from the subtraction of the position coordinates of the needle center position c1 in the absolute coordinate system from the position coordinates of the center position c0 in the absolute coordinate system is set to a compensation value, and the compensation value is converted into a value in the front-end coordinate system. Subsequently, the result of this conversion is added to the pre-calibration center position stored in control unit 90 to obtain a new needle center position for correction purposes.
[0069] The compensation can be performed by subtracting the center position c0 from the position coordinates of the needle center position c2 in the absolute coordinate system.
[0070] Accordingly, the precise needle center position of sewing machine 10 is calculated (step S13).
[0071] To update, the CPU then replaces the sewing machine's needle center position data within data memory 94 with XY coordinate data in the front end area coordinate system, which indicates a newly obtained needle center position of the sewing machine (step S15).
[0072] Accordingly, the calibration process is complete.
[0073] The calibration process can be configured to be performed on the sewing system 100 as follows: only once at an initial stage before shipping, each time the main power supply of the sewing machine 100 is switched on, and periodically. The calibration process can be performed from any operating area provided together with the control unit 90. Acquisition processing of an amount of dead weight in the sewing system
[0074] The joint 113 of the robot arm 110 can cause backlash if the direction of rotation is reversed.
[0075] However, since in most cases a rotational axis of joint 113, which is different from the first joint 113A, is in a state in which an inclination with respect to the vertical upward and downward direction occurs according to a change in the attitude of the robot arm 110, dead-slip occurs only with difficulty under the influence of gravity, but since only the rotational axis of the first joint 113A always maintains the vertical upward and downward direction, dead-slip occurs easily.
[0076] Because the first joint 113A is the joint of the robot arm 110 that is closest to the base end area (of a substructure), when backlash occurs, it is easy for the greatest influence on the precision of the position to be exerted on the front end area of the robot arm 110. Therefore, the control unit 90 performs the acquisition processing, which acquires a value for backlash in the first joint 113A.
[0077] Fig. Figure 8 is a flowchart for the acquisition processing of the amount of dead load, which is executed by the CPU 91 of the control unit 90 based on the program.
[0078] First, the CPU 91 performs a processing operation in which position coordinate data in the absolute coordinate system, which specify a predetermined target position, are read from the data memory 94 (step S31).
[0079] Next, the CPU 91 causes the servomotor 114 of each of the robot arms 110 to transport the sewing machine 10 to the predetermined target stitch position (step S33).
[0080] At this time, the first joint 113A of the robot arm 110 transports the sewing machine 10 along a path to reach the target stitch position, while the rotation operation is performed in a fixed direction (for example, in a clockwise direction).
[0081] A workpiece or holding device is installed in a prescribed target position, which is easily recognizable from the capture image of the stitch position when the stitch is performed.
[0082] Next, in the target position, the CPU 91 initiates the drive of the sewing machine motor 24, thus executing the first stitch to form a third stitch position (step S35). At this point, the sewing machine 10 maintains the reference position, in which the longitudinal direction (the up and down direction of the needle) of the needle bar 12 is parallel to the vertical up and down direction, and executes the stitch.
[0083] Next, the CPU 91 causes only the first joint 113A of the robot arm 110 to rotate at a predetermined angle of rotation in the fixed direction (for example, clockwise), as described above, and then performs the rotation operation at the same angle of rotation in the opposite direction (for example, counterclockwise) and performs a transport operation to return the sewing machine 10 to the target stitch position described above (step S37).
[0084] In the target position, the drive of the sewing machine motor 24 is initiated again to execute the second stitch and form a fourth stitch position (step S39).
[0085] Next, the CPU 91 causes the servomotor 114 of each of the robot arms 110 to be driven, so that both the first and second stitch positions also fall within the image capture area of the camera 15, and thereby causes the sewing machine 10 to be moved so that the camera 15 can capture images of the third and fourth stitch positions (step S41).
[0086] Fig. Figure 9 is an explanatory diagram showing images of the third and fourth stitch positions.
[0087] Pattern matching and similar operations are performed by the image processing unit 15a using the captured image to extract the third and fourth stitch positions. The CPU 91 calculates the amount of dead travel in the first joint 113A (step S43).
[0088] This means that the CPU 91 specifies third stitch positions p31 and p32 as well as fourth stitch positions p41 and p42, which result from the first two sewing needles that are extracted, in the absolute coordinate system.
[0089] From these, the CPU 91 calculates a distance d between the stitch positions p31 and p41 from a distance within the capture image, focusing on the stitch positions p31 and p41, which result from the same sewing needle 11 (which may be the stitch positions p32 and p42).
[0090] The CPU 91 detects the angles of all joints 113 of the robot arm 110 from the encoder 115 and calculates a distance from the central axis of the first joint 113A of the robot arm 110 to the front end of the arm, viewed from above. A distance R from the central axis of the first joint 113A to the sewing needle 11, viewed from above, is calculated with reference to the position coordinates of the needle center position of the sewing machine 10. This position is obtained from design data concerning a distance from a holding position of the sewing machine 10 at the front end of the robot arm 110 to the sewing needle 11, or it is obtained in the calibration process described above.
[0091] On the other hand, in a case where the distance d is sufficiently smaller than the distance R, with a certain amount of dead travel in the first joint 113A, because this is considered to be R sinθ = d, a calculation using the angle θ = sin 1(d / R) performed, which indicates the amount of free movement in the first joint 113A.
[0092] The CPU 91 records a value of the angle θ, which indicates the amount of dead travel in the first joint 113A, with the data memory 94 (step S45) and completes the acquisition processing of the amount of dead travel. In a case where, during the operation of the robot arm 110, the rotation direction of the first joint 113A is reversed, the amount of dead travel is referred to as the compensation value.
[0093] The acquisition processing of the amount of dead thread can be configured to be carried out in the sewing system 100 as follows: only once in the initial stage before shipping, every time the main power supply of the sewing system 100 is switched on, and periodically, and it can be carried out arbitrarily from the operating area which is provided together with the control device 90. Effects of embodiments
[0094] In the sewing system 100 described above, the control unit 90 executes the stitch before and after it causes the rotation about the axis of rotation, which passes through the pre-calibration needle center position stored in the control unit 90, in order to rotate the sewing machine 10 at a predetermined angle. Furthermore, the control unit 90 performs the calibration processing, which calibrates the needle center position stored in the control unit 90 based on the first stitch positions p11 and p12 and the second stitch positions p21 and p22 within the image acquisition areas of the acquisition images. These images are obtained by capturing the images of the first stitch positions p11 and p12 and the second stitch positions p21 and p22, which are formed as a consequence of the stitch execution, using the camera 15.
[0095] For this reason, the control unit 90 can precisely detect the actual needle center position of the sewing machine 10 by controlling each area of the sewing system 100 without performing measurements or the like that require human intervention, and the robot arm 110 can precisely position the stitch position of the sewing machine 10. Thus, it is possible to achieve an improvement in sewing quality.
[0096] It is possible to reduce the workload associated with calibration processing.
[0097] Furthermore, in the sewing system 100 described above, the control unit 90, for the target stitch position, captures the images of the third stitch positions p31 and p32, which are formed after positioning by rotation in a fixed direction in the first joint 113A, and the fourth stitch positions p41 and p42, which are formed after positioning by rotation in the opposite direction in the first joint 113A, using the camera 15. The control unit 90 also performs the acquisition processing of the amount of play that occurs in the first joint 113A, based on each of the third stitch positions p31 and p32 and the fourth stitch positions p41 and p42 within the image acquisition areas of the captured images.
[0098] For this reason, by acquiring the amount of dead travel that occurs in the first joint 113A of the sewing machine 10, the control of the operation for the compensation, in which the amount of dead travel is taken into account, is carried out in the operation of positioning the stitch position of the sewing machine 10. Thus, because the robot arm 110 can precisely position the stitch position of the sewing machine 10, it is possible to achieve a further improvement in sewing quality. Further
[0099] During calibration processing, the images of the stitch position resulting from the first stitch and the stitch position resulting from the second needle stitch are captured at the same time; however, image capture can also be done individually for each stitch.
[0100] The same applies in the case of the acquisition process for the amount of the death charge.
[0101] In the sewing machine 10, the optical axis of the camera 15 runs forwards to be parallel to the longitudinal direction of the needle bar 12; however, the optical axis of the camera 15 can also run in a downward tilting direction.
[0102] The laser 16 is used as a light source which emits the slit light towards the workpiece so that the camera 15 can appropriately capture the image of the reference line; however, any device which can emit the slit light, for example an LED or an electric lamp, can be used.
Claims
Sewing system (100) comprising: a sewing machine (10); a camera (15) which captures an image of a reference position for sewing; a robot arm (110) which holds the sewing machine (10) and the camera (15); and a control device (90) wherein the control device (90) controls the following operations: forming a first stitch position (p11, p12) which results from a stitch formation of the sewing machine (10);and forming a second stitch position (p21, p22) resulting from stitch formation by the sewing machine (10) after the sewing machine (10) has been rotated at a prescribed angle about an axis of rotation which passes through a needle center position stored by the control device (90), and wherein the control device (90) further performs a calibration process which calibrates the needle center position stored by the control device (90) based on each position of the first stitch position (p11, p12) and the second stitch position (p21, p22) within image acquisition areas of acquisition images obtained by acquiring images of the first stitch position (p11, p12) and the second stitch position (p21, p22) using the camera (15). Sewing system (100) according to claim 1, wherein the robot arm (110) comprises a first joint (113A) which causes the entire robot arm (110) to rotate about an axis in a vertically upward and downward direction, wherein the control device (90) for a stitch position which is to be set as a target controls the following operations: forming a third stitch position (p31, p32) using the sewing machine (10) after a positioning operation which results from a rotation in a fixed direction in the first joint (113A), and forming a fourth stitch position (p41, p42) using the sewing machine (10) after a positioning operation which results from a rotation in a direction opposite to the fixed direction in the first joint (113A); capturing images of the third stitch position (p31, p32) and the fourth stitch position (p41, p42) using the camera (15);and acquiring an amount of dead mandible occurring in the first joint (113A) based on each position of the third stitch position (p31, p32) or the fourth stitch position (p41, p42) within image acquisition areas.;