Robot system and position detection method

Abstract

The invention provides a robot system and a position detection method capable of detecting the position of a tool with high precision. The robot system includes: a robot arm; the tool is mounted on the mechanical arm; a plurality of optical sensors which are disposed so that the relative positional relationship with the tool is constant, and which detect the amount of translation with respect to an object; and a control device that detects a translation amount and a rotation amount of the tool on the basis of the translation amounts detected by the plurality of optical sensors, and detects a position of the tool on the basis of the translation amount and the rotation amount of the tool.

Description

Technical Field

[0001] The present invention relates to a robot system and a position detection method. Background Art

[0002] The printing system described in Patent Document 1 prints on an object by causing a robot having a print head mounted at the front end to move and eject ink toward the object. In addition, the printing system has a rotation angle sensor and a piezoelectric actuator. The rotation angle sensor is used to detect the actual position of the print head. The piezoelectric actuator is arranged between the print head and corrects the position of the print head according to the actual position of the print head. In this way, by correcting the position of the print head according to the actual position of the print head, printing without stripes (gaps) is achieved.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-202781

[0004] However, in the printing system of Patent Document 1, it is difficult to detect the change in the posture of the printing head relative to the translation direction due to the arrangement of the rotation angle sensor. Therefore, there is a problem that the detection accuracy of the actual position of the printing head is low and high-precision printing cannot be performed. Summary of the invention

[0005] The robot system of the present invention comprises: a robot arm;

[0006] a tool mounted on the robotic arm; and

[0007] a plurality of optical sensors arranged in a fixed relative position relationship with the tool and detecting the amount of translation relative to the object; and

[0008] The control device detects the translation amount and the rotation amount of the tool based on the translation amounts detected by the plurality of optical sensors, and detects the position of the tool based on the translation amount and the rotation amount of the tool.

[0009] The position detection method of the present invention comprises: a robot arm; a tool mounted on the robot arm; and a plurality of optical sensors arranged in a fixed relative position relationship with the tool and detecting a translation amount relative to an object.

[0010] The position detection method detects the translation amount and the rotation amount of the tool based on the translation amounts detected by the plurality of optical sensors, and detects the position of the tool based on the translation amount and the rotation amount of the tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is an overall diagram of the robot system according to the first embodiment.

[0012] Figure 2 It is a schematic diagram showing the status of a print job.

[0013] Figure 3 is a top view showing the mobile station.

[0014] Figure 4 is a cross-sectional view of an optical sensor.

[0015] Figure 5 is a schematic diagram showing the detection principle of the optical sensor.

[0016] Figure 6 This is a schematic diagram for explaining the problems of optical sensors.

[0017] Figure 7 This is a schematic diagram for explaining a method of detecting the amount of translation and the amount of rotation.

[0018] Figure 8 It is a schematic diagram for explaining a method of detecting a rotation amount.

[0019] Fig. 9 It is a schematic diagram for explaining a method of detecting a rotation amount.

[0020] Fig.10 It is a top view showing a modified example of the arrangement of the optical sensor.

[0021] Fig.11 It is a top view showing a modified example of the arrangement of the optical sensor.

[0022] Fig.12 It is a top view showing a modified example of the arrangement of the optical sensor.

[0023] Fig.13 It is a top view showing a modified example of the arrangement of the optical sensor.

[0024] Fig.14 It is a top view showing a modified example of the arrangement of the optical sensor.

[0025] Fig.15 It is a top view showing a modified example of the arrangement of the optical sensor.

[0026] Fig.16 It is a top view showing a modified example of the arrangement of the optical sensor.

[0027] Fig.17 It is an overall diagram of a robot system according to a second embodiment.

[0028] Fig.18 It is a schematic diagram showing the status of a print job.

[0029] Fig.19 It is a schematic diagram showing the status of a print job.

[0030] Fig. 20 It is a schematic diagram showing the status of a print job.

[0031] Fig.21 It is an overall diagram of a robot system according to a third embodiment.

[0032] Description of Reference Numerals

[0033] 1: robot system; 2: robot; 21: base; 22: robot arm; 221: arm; 222: arm; 223: arm; 224: arm; 225: arm; 226: arm; 3: print head; 31: ink ejection hole; 4: moving stage; 40: base; 400: piezoelectric actuator; 41: first stage; 42: second stage; 45: first stage driving unit; 46: second stage driving unit; 5: optical sensor; 5A: first optical sensor; 5B: second optical sensor; 5C: third optical sensor; 5D: fourth optical sensor; 50: optical tracking sensor; 51: base; 521: lens component; 522: lens component; 53: light source; 54: imaging element; 55: processing circuit; 59: holding component; 6: contact part ;7: force sensor;8: conveyor belt;81: camera;9: control device;A: first direction;B: second direction;D: separation distance;F: plane;Gn: image;Gn-1: image;I: ink;J1: joint;J2: joint;J3: joint;J4: joint;J5: joint;J6: joint;L: light;O: rotation center;P1: position;P2: position;P3: position;Pn: position posture;Pn-1: position posture;Q: printing track;W: object;ΔLa: moving distance;ΔLb: moving distance;Δx: translation amount;Δx3: translation amount;Δxa: translation amount;Δxb: translation amount;Δy: translation amount;Δy3: translation amount;Δya: translation amount;Δyb: translation amount;Δθ: rotation amount. DETAILED DESCRIPTION

[0034] Hereinafter, the robot system and the position detection method of the present invention will be described in detail based on the embodiments shown in the drawings.

[0035] First embodiment

[0036] Figure 1 It is an overall diagram of the robot system according to the first embodiment. Figure 2 It is a schematic diagram showing the status of a print job. Figure 3 is a top view showing the mobile station. Figure 4 is a cross-sectional view of an optical sensor. Figure 5 is a schematic diagram showing the detection principle of the optical sensor. Figure 6 This is a schematic diagram for explaining the problems of optical sensors. Figure 7 This is a schematic diagram for explaining a method of detecting the amount of translation and the amount of rotation. Figure 8 and Fig. 9 Each of them is a schematic diagram for explaining a method of detecting a rotation amount. Figures 10 to 16 Each of them is a plan view showing a modified example of the arrangement of the optical sensor.

[0037] Figure 1 The robot system 1 shown is applied to a printing system that performs a printing operation on an object W. The robot system 1 includes a robot 2, a printing head 3 as a tool mounted on the front end of the robot 2, a moving stage 4 disposed between the robot 2 and the printing head 3, a plurality of optical sensors 5 disposed on the printing head 3, and a control device 9 that controls the driving of the robot 2.

[0038] Robot 2

[0039] The robot 2 is a six-axis vertical multi-joint robot with six drive axes, and has a base 21 fixed to a mounting table, a floor, etc. and a robot arm 22 rotatably connected to the base 21. The robot arm 22 is a structure in which six arms 221, 222, 223, 224, 225, and 226 are rotatably connected in sequence from the side of the base 21, and has six joints J1, J2, J3, J4, J5, and J6. Among these joints J1 to J6, the joints J2, J3, and J5 are bending joints, and the joints J1, J4, and J6 are torsion joints. In addition, a driving mechanism with a motor and an encoder is provided at each of the joints J1, J2, J3, J4, J5, and J6, and the motor is driven by servo control of the output of the feedback encoder.

[0040] However, the structure of the robot 2 is not particularly limited. For example, the number of arms provided by the robot arm 22 is not limited to six. In addition, the robot 2 may also be a dual-arm robot, a horizontal multi-joint robot (SCARA robot), etc. In addition, the robot 2 may not be fixed to a mounting table, a floor, etc., but may be able to move on its own.

[0041] Printing head 3

[0042] The print head 3 is disposed at the front end of the robot arm 22, that is, the arm 226. The print head 3 is not particularly limited, but an inkjet head is used in this embodiment. The inkjet head includes an ink chamber (not shown), a vibration plate disposed on the wall of the ink chamber, and an ink ejection hole 31 connected to the ink chamber. The vibration plate vibrates to eject the ink I in the ink chamber from the ink ejection hole 31. Figure 2 As shown, the printing is performed by driving the robot arm 22 to move the print head 3 on a predetermined printing track Q relative to the object W, and then ejecting ink I from the print head 3 and causing it to adhere to the printed surface of the object W.

[0043] In addition, in the present embodiment, the tool is the printing head 3 , but the present invention is not limited thereto and can be changed as appropriate depending on the work to be performed on the object W.

[0044] Mobile Station 4

[0045] The movable platform 4 is disposed between the arm 226 and the printing head 3 and is used to correct the position of the printing head 3. Figure 3 As shown, the movable stage 4 includes a base 40 supported by an arm 226 , a first stage 41 that moves straightly in a first direction A relative to the base 40 , and a second stage 42 that moves straightly in a second direction B orthogonal to the first direction A relative to the first stage 41 . The printing head 3 is arranged on the second stage 42 .

[0046] The moving stage 4 includes a first stage driving unit 45 that moves the first stage 41 in the first direction A relative to the base 40 and a second stage driving unit 46 that moves the second stage 42 in the second direction B relative to the first stage 41 .

[0047] The first stage driving unit 45 and the second stage driving unit 46 are respectively equipped with a piezoelectric actuator 400 driven by the expansion and contraction of the piezoelectric element caused by the energization, and the first stage 41 and the second stage 42 are moved by transmitting the vibration of the piezoelectric actuator 400 to them. In this way, by using the piezoelectric actuator 400, the movement amount and movement speed of the first stage 41 and the second stage 42 can be finely and accurately controlled, and the switching of the movement direction also becomes agile. Therefore, the position correction of the printing head 3 can be performed with high precision. In addition, the miniaturization and lightweight of the mobile stage 4 can also be achieved. Therefore, the increase in the front end weight of the robot 2 due to the configuration of the mobile stage 4 can be minimized, and the reduction in the driving characteristics of the robot 2 such as responsiveness and vibration reduction can be effectively suppressed.

[0048] However, the structure of the moving stage 4 is not particularly limited. For example, the first stage driving unit 45 and the second stage driving unit 46 may be structures using a driving source other than the piezoelectric actuator 400, such as a motor that rotates by energizing. In addition, the moving stage 4 may be omitted. In this case, the position correction of the printing head 3 can be performed by the robot arm 22.

[0049] Optical sensor 5

[0050] like Figure 3 As shown, the optical sensor 5 is disposed on the second stage 42 of the moving stage 4 together with the print head 3. Based on the output of the optical sensor 5, the position and posture (hereinafter also simply referred to as "position and posture") of the print head 3 are detected.

[0051] The optical sensor 5 is an optical tracking sensor 50 which is also widely used in optical mice. The optical tracking sensor 50 has two mutually orthogonal detection axes, namely, the x-axis and the y-axis, and can detect the translation amount Δx in the x-axis direction and the translation amount Δy in the y-axis direction independently. In addition, the optical tracking sensor 50 is in a rectangular shape extending along the y-axis when viewed from above. However, the shape of the optical tracking sensor 50 is not particularly limited, and can be a rectangular shape extending along the x-axis, a square, a circle, etc.

[0052] like Figure 4 As shown, the optical tracking sensor 50 includes a base 51, a pair of lens components 521 and 522, a light source 53, an imaging element 54, and a processing circuit 55. The base 51 is arranged to face the object W. The light L emitted by the light source 53 is guided to the surface of the object W by the lens component 521 and the reflection surface formed on the inner surface of the base 51, reflected by the surface of the object W, focused by the lens component 522, and received by the imaging element 54. The imaging element 54 continuously takes pictures at a cycle of about 1 ms, and the processing circuit 55 obtains the translation amount of the optical tracking sensor 50 relative to the object W based on the image obtained by the imaging element 54.

[0053] Specifically, by irradiating light L to the object W, Figure 5 As shown, in the image captured by the imaging element 54, light and dark corresponding to the minute concave-convex of the surface of the object W appear. Furthermore, the processing circuit 55 compares the image Gn newly captured by the imaging element 54 with the image Gn-1 captured last time, and detects the movement amount of the image Gn relative to the image Gn-1 using the optical flow method or the like. Furthermore, based on the detection result, the processing circuit 55 detects the translation amount Δx in the x-axis direction and the translation amount Δy in the y-axis direction of the optical tracking sensor 50 relative to the object W from the time when the image Gn-1 is acquired to the time when the image Gn is acquired. In particular, as shown in the present embodiment, by irradiating the object W with light L from an oblique direction, that is, a direction oblique to the normal of the printed surface of the object W, the light and dark appear more clearly, so that the translation amounts Δx and Δy can be detected with higher accuracy.

[0054] In addition, the light source 53 is not particularly limited, and for example, an LED (light emitting diode), a laser light source, etc. can be used. In addition, the light L from the light source 53 is not particularly limited, and for example, red light, blue light, infrared light, etc. can be used. In addition, the imaging element 54 is not particularly limited, and for example, a CCD image sensor, a CMOS image sensor, etc. can be used.

[0055] The optical tracking sensor 50 has been described above. As can be seen from the fact that the optical tracking sensor 50 is widely used in optical mice, it is cheap and small, and has high detection accuracy. Therefore, by using the optical tracking sensor 50 as the optical sensor 5, a robot system 1 that can achieve both low price and small size and high-precision position detection can be obtained.

[0056] However, as described above, the optical tracking sensor 50 can only detect the translation amounts Δx and Δy of the optical tracking sensor 50 between the compared images, but cannot detect the rotation amount Δθ. Figure 6 As shown, when the optical sensor 5 moves to positions P1, P2, and P3 in sequence while performing translational and rotational motions in which translational motion and rotational motion are mixed, the deviation between the actual position shown by the solid line and the detection position shown by the dot-dash line gradually increases.

[0057] Due to such a problem, a simple printing track Q without rotational motion needs to be set, and a complex printing track Q with rotational motion cannot be set. Therefore, complex printing cannot be performed. Therefore, in order to eliminate such a problem, the robot system 1 is configured to use a plurality of optical sensors 5, which can detect not only the translation amounts Δx and Δy but also the rotation amount Δθ. Thus, a complex printing track Q with rotational motion can be set, and more complex printing can be performed.

[0058] Specifically, the robot system 1 includes a first optical sensor 5A and a second optical sensor 5B as two optical sensors 5. The first optical sensor 5A and the second optical sensor 5B are both optical tracking sensors 50 and have the same configuration as each other.

[0059] like Figure 3 As shown in FIG. 4 , the first optical sensor 5A and the second optical sensor 5B are both arranged on the second stage 42 via a holding member 59. Therefore, the relative positional relationship between the first optical sensor 5A and the second optical sensor 5B and the print head 3 remains fixed. In addition, the holding member 59 functions as a spacer for adjusting the separation distance between the first optical sensor 5A and the second optical sensor 5B and the object W during the printing operation.

[0060] In addition, the first optical sensor 5A and the second optical sensor 5B are arranged so that the x-axis coincides with the first direction A and the y-axis coincides with the second direction B. In this way, by aligning the moving direction of the moving stage 4 with the detection axis of the first optical sensor 5A and the second optical sensor 5B, a transformation function for aligning them is not required or the transformation function becomes simple. Therefore, it is easy to create a control program for the robot system 1.

[0061] In addition, the first optical sensor 5A and the second optical sensor 5B are arranged side by side and separated in the first direction A, and the print head 3 is arranged between the first optical sensor 5A and the second optical sensor 5B. That is, the first optical sensor 5A and the second optical sensor 5B are arranged on the opposite side of the first direction A relative to the print head 3. As a result, the first optical sensor 5A and the second optical sensor 5B can be arranged near the print head 3, so the position and posture of the print head 3 can be detected with higher accuracy. In particular, in the present embodiment, the first optical sensor 5A and the second optical sensor 5B are arranged symmetrically relative to the print head 3. Therefore, the function for obtaining the position and posture of the print head 3 from the outputs of the first optical sensor 5A and the second optical sensor 5B becomes simple, and accordingly, the creation of the control program of the robot system 1 becomes easy. In addition, the coordinates of the first optical sensor 5A, the second optical sensor 5B and the print head 3 are respectively known and stored in the control device 9 in advance.

[0062] In addition, if Figure 2 As shown, the first optical sensor 5A and the second optical sensor 5B are arranged on the same plane F including the first direction A (direction along the x-axis) and the second direction B (direction along the y-axis). During the printing operation, the print head 3 is moved while keeping the plane F including the first direction A and the second direction B substantially parallel to the printed surface of the object W. Therefore, by forming such a configuration, the separation distance between the first optical sensor 5A and the second optical sensor 5B and the object W can be equal. Therefore, the detection conditions of the first optical sensor 5A and the second optical sensor 5B can be made equal to each other, so that the detection error between the first optical sensor 5A and the second optical sensor 5B can be suppressed. As a result, the position and posture of the print head 3 can be detected with higher accuracy.

[0063] However, the arrangement of the first optical sensor 5A and the second optical sensor 5B is not particularly limited as long as the relative positional relationship with the print head 3 remains fixed. For example, the first optical sensor 5A and the second optical sensor 5B may be directly arranged on the second stage 42 without being disposed via the holding member 59. In addition, the first optical sensor 5A and the second optical sensor 5B may not be disposed on the second stage 42, but may be disposed on the print head 3 directly or via a holding member.

[0064] In addition, in the present embodiment, the front end surfaces of the first optical sensor 5A and the second optical sensor 5B are flush with the front end surface of the print head 3, but the present invention is not limited thereto, and the front end surfaces of the first optical sensor 5A and the second optical sensor 5B may protrude toward the object W side relative to the front end surface of the print head 3, or may be retracted toward the moving stage 4. This arrangement may be appropriately set according to the recommended separation distance from the object W set in the print head 3, the recommended separation distance from the object W set in the first optical sensor 5A and the second optical sensor 5B, and the like.

[0065] Control device 9

[0066] The control device 9 controls the driving of the robot 2, the printing head 3, and the moving stage 4 independently or in conjunction with each other. The control device 9 is composed of, for example, a computer, and has a processor (CPU) for processing information, a memory connected to the processor in a communicable manner, and an external interface for connecting to an external device. The memory stores various programs that can be executed by the processor, and the processor can read and execute the programs stored in the memory.

[0067] The configuration of the robot system 1 has been described above. Figure 7 Taking the case of the translation and rotation motion as shown as an example, a method of detecting the position of the print head 3 using the first optical sensor 5A and the second optical sensor 5B will be described.

[0068] In this case, the first optical sensor 5A detects its own translation amount Δxa (Δx) and translation amount Δya (Δy) by the above method, and sends the result to the control device 9. Similarly, the second optical sensor 5B detects its own translation amount Δxb (Δx) and translation amount Δyb (Δy) by the above method, and sends the result to the control device 9. In addition, the first optical sensor 5A and the second optical sensor 5B are synchronized and controlled to take pictures at the same timing by the imaging element 54. As a result, the position and posture of the print head 3 can be detected with higher accuracy.

[0069] The control device 9 calculates the average value (Δya+Δyb) / 2 of the translation amounts Δya and Δyb as the translation amount Δy3 of the print head 3 in the y-axis direction. Similarly, the control device 9 calculates the average value (Δxa+Δxb) / 2 of the translation amounts Δxa and Δxb as the translation amount Δx3 of the print head 3 in the x-axis direction. Furthermore, the control device 9 calculates the rotation amount Δθ of the print head 3 based on the difference (Δya-Δyb) between the translation amounts Δya and Δyb and the separation distance D between the first optical sensor 5A and the second optical sensor 5B.

[0070] Furthermore, the control device 9 detects the latest position and posture Pn of the print head 3 by adding the position and posture Pn-1 of the print head 3 detected last time to the translation amounts Δx3, Δy3 and the rotation amount Δθ detected this time. Whenever the first optical sensor 5A and the second optical sensor 5B send new translation amounts Δx and Δy, the control device 9 repeats the above-mentioned processing to update the latest position and posture of the print head 3. In addition, the control device 9 can also detect the trajectory of the print head 3 by combining the detected position and posture in a time series. In this way, by using a plurality of optical sensors 5 that can only detect translational motion alone, it is possible to easily detect not only the translational motion of the print head 3 but also the rotational motion. Moreover, according to such a method, the position and posture of the print head 3 can be detected with high precision.

[0071] In addition, the method for detecting the translation amount and rotation amount of the print head 3 is not limited to the above method. For example, either the translation amount Δya or Δyb may be used as the translation amount of the print head 3 in the y-axis direction. Similarly, either the translation amount Δxa or Δxb may be used as the translation amount of the print head 3 in the x-axis direction.

[0072] On the other hand, the rotation amount Δθ can also be calculated using, for example, the distance measurement method. In this case, Figure 8 As shown, the moving distance ΔLa of the first optical sensor 5A is represented by (p+d)Δθ, and the moving distance ΔLb of the second optical sensor 5B is represented by (pd)Δθ. Moreover, according to these two equations, the rotation amount Δθ=(ΔLa-ΔLb) / 2d. The rotation amount Δθ can also be easily detected by such a method. p is the distance from the rotation center O to the print head 3, and d is D / 2. In addition, ΔLa can be obtained as the resultant force of the translation amounts Δxa and Δya, and ΔLb can be obtained as the resultant force of the translation amounts Δxb and Δyb.

[0073] Alternatively, the translation amounts Δx3 and Δy3 of the print head 3 may be detected based on the translation amounts Δx and Δy of the first optical sensor 5A, and the rotation amount Δθ of the print head 3 may be detected based on the translation amounts Δx and Δy of the second optical sensor 5B. In this case, the translation amounts Δx and Δy of the first optical sensor 5A are set to translation amounts Δx3 and Δy3. Fig. 9 As shown, the rotation center O is set to the center of the first optical sensor 5A, and the rotation amount Δθ is detected based on the translation amount Δy of the second optical sensor 5A and the separation distance D (the separation distance between the rotation center and the second optical sensor 5B). In addition, the rotation center O is not particularly limited and can be appropriately set according to the printing track Q.

[0074] The above is a description of the position and posture detection method of the print head 3 using the first optical sensor 5A and the second optical sensor 5B. Next, a printing operation of printing on an object W using the robot system 1 is briefly described. The control device 9 moves the print head 3 along the indicated printing track Q by controlling the drive of the robot 2, and ejects ink I from the print head 3 to the object W at the indicated timing. In addition, the control device 9 periodically detects the latest position and posture of the print head 3 using the above-mentioned position and posture detection method during the movement of the print head 3 on the printing track Q, and controls the drive of the moving stage 4 so that the detected position and posture are consistent with the printing track Q. As a result, the deviation of the actual printing track from the printing track Q can be suppressed, and a high-quality printing operation can be performed. In particular, since the deviation of the printing track is corrected by the drive of the moving stage 4, the printing track can be corrected quickly and with high precision, for example, compared with when the deviation of the printing track is corrected by the drive of the robot 2. Therefore, a higher-quality printing operation can be performed.

[0075] Furthermore, in the above, the offset between the printing track Q and the actual printing track is detected in real time while the printing operation is being performed, and the offset is fed back to control the drive of the movable table 4, but the method of the printing operation is not limited to this. For example, before performing the actual printing operation, a test run is performed to move the printing head 3 along the printing track Q, and the actual printing track is obtained in advance. Then, the offset between the obtained actual printing track and the printing track Q is calculated, and a drive instruction for the movable table 4 is generated to correct the offset. Moreover, in the actual printing operation, the position and posture of the printing head 3 is not detected, and the printing head 3 is moved along the printing track Q while the movable table 4 is moved by the generated drive instruction. According to such a method, the offset between the printing track Q and the actual printing track can also be reduced, so that high-quality printing operations can be performed.

[0076] The robot system 1 and the position detection method have been described above. As described above, such a robot system 1 includes: a robot arm 22; a print head 3 as a tool, which is mounted on the robot arm 22; a plurality of optical sensors 5, which are arranged in a fixed relative positional relationship with the print head 3 and detect the translation amounts Δx and Δy relative to the object W; and a control device 9, which detects the translation amounts Δx3, Δy3 and the rotation amount Δθ of the print head 3 based on the translation amounts Δx and Δy detected by the plurality of optical sensors 5, and detects the position of the print head 3 based on the translation amounts Δx3, Δy3 and the rotation amount Δθ of the print head 3. In this way, the rotation amount Δθ can be detected by using the translation amounts Δx and Δy detected by the plurality of optical sensors 5. Therefore, the posture change of the print head 3 with respect to the translation direction can be easily detected, and the position of the print head 3 can be detected with high accuracy.

[0077] As described above, the optical sensor 5 is an optical tracking sensor 50, which includes a light source 53, a lens component 521 for irradiating the light L from the light source 53 to the object W, and an imaging element 54 for receiving the light L reflected by the object W. The image movement amount is calculated by comparing a plurality of images captured by the imaging element 54, thereby detecting the translation amounts Δx and Δy relative to the object W. In this way, by using the optical tracking sensor 50 as the optical sensor 5, a robot system 1 is provided that can realize both low cost and small size and high-precision position detection.

[0078] As described above, the optical sensor 5 irradiates the object W with light L from an oblique direction. This makes it easier for light and dark corresponding to minute irregularities on the surface of the object W to appear in the image captured by the imaging element 54, and the translation amounts Δx and Δy relative to the object W can be detected with high accuracy.

[0079] As described above, the optical sensor 5 has two mutually orthogonal detection axes, ie, the x-axis and the y-axis. Thus, the optical sensor 5 can detect the translation amounts Δx and Δy. Therefore, the two-dimensional movement of the print head 3 can be easily detected.

[0080] As described above, the print head 3 is disposed between the plurality of optical sensors 5. Thus, the plurality of optical sensors 5 can be disposed near the print head 3, respectively, and thus the posture of the print head 3 can be detected with higher accuracy.

[0081] As described above, the tool is the print head 3, and the printing operation is performed on the object W. Thus, a high-quality printing operation can be performed.

[0082] In addition, as described above, the control device 9 corrects the print track Q of the print head 3 based on the detected position of the print head 3. This can suppress the deviation between the actual print track and the print track Q, and can perform a higher quality printing operation.

[0083] In addition, as described above, the position detection method includes: the robot arm 22; the print head 3 as a tool, which is mounted on the robot arm 22; and the plurality of optical sensors 5, which are arranged in a fixed relative positional relationship with the print head 3 and detect the translation amounts Δx and Δy relative to the object W, and the position detection method detects the translation amounts Δx3 and Δy3 and the rotation amount Δθ of the print head 3 based on the translation amounts Δx and Δy detected by the plurality of optical sensors 5, and detects the position of the print head 3 based on the translation amounts Δx3, Δy3 and the rotation amount Δθ of the print head 3. In this way, the rotation amount Δθ can be detected by using the translation amounts Δx and Δy detected by the plurality of optical sensors 5. Therefore, the posture change of the print head 3 with respect to the translation direction can be easily detected, and the position of the print head 3 can be detected with high accuracy.

[0084] The first embodiment of the robot system 1 is described above, but the configuration and number of the optical sensors 5 are not particularly limited. Figures 10 to 16 Configuration shown.

[0085] exist Fig.10 In the illustrated configuration, the first optical sensor 5A and the second optical sensor 5B are separately arranged in the first direction A and the second direction B, respectively, and the print head 3 is arranged between them. Fig.11 In the structure shown, the first optical sensor 5A is Fig.10 The structure shown is further rotated 90° and configured. Fig.12 In the structure shown, the second optical sensor 5B is Fig.11 The structure shown is further rotated by 90 degrees.

[0086] In addition, Fig.13 In the configuration shown, the first optical sensor 5A and the second optical sensor 5B are arranged side by side in the second direction B. Fig.14 In the structure shown, the first optical sensor 5A is Fig.13 The structure shown is further rotated 90° and configured. Fig.15 In the structure shown, the second optical sensor 5B is Fig.14 The structure shown is further rotated by 90 degrees.

[0087] In addition, Fig.16 In the illustrated configuration, four optical sensors 5 are provided, namely, a first optical sensor 5A, a second optical sensor 5B, a third optical sensor 5C, and a fourth optical sensor 5D.

[0088] Second embodiment

[0089] Fig.17 It is an overall diagram of a robot system according to a second embodiment. Figures 18 to 20 Each of them is a schematic diagram showing the status of a printing job.

[0090] The robot system 1 involved in this embodiment is the same as the robot system 1 of the first embodiment except that a force sensor 7 is provided on the robot 2. In addition, in the following description, the robot system 1 of this embodiment is mainly described with respect to the differences from the first embodiment, and the description of the same matters is omitted. In addition, in each figure of this embodiment, the same reference numerals are attached to the same components as those in the above embodiment.

[0091] like Fig.17As shown, in the robot system 1 of the present embodiment, the first optical sensor 5A and the second optical sensor 5B are arranged to protrude toward the object W side relative to the print head 3. In addition, a force sensor 7 is arranged between the robot 2 and the moving stage 4. The force sensor 7 has three mutually orthogonal detection axes, and can independently detect the translation force (axial force) along each detection axis and the rotation force (torque) around each detection axis. In the robot system 1, the contact between the first optical sensor 5A and the second optical sensor 5B and the object W is detected using the force sensor 7.

[0092] According to such a configuration, by feeding back the detection result of the force sensor 7, Fig.18 As shown, the first optical sensor 5A and the second optical sensor 5B can be brought into light contact with the object W with a predetermined force and the print head 3 can be moved along the print track Q. According to such a method, the separation distance between the first optical sensor 5A and the second optical sensor 5B and the object W can be kept constant (zero). Therefore, the detection error of the first optical sensor 5A and the second optical sensor 5B caused by the change of the separation distance between the first optical sensor 5A and the second optical sensor 5B and the object W can be reduced, so that the translation amounts Δx and Δy can be detected with higher accuracy. In addition, the separation distance between the print head 3 and the object W can be kept constant, so that higher quality printing can be performed.

[0093] In addition, in the above example, the first optical sensor 5A and the second optical sensor 5B are brought into contact with the object W, but the present invention is not limited thereto. Fig.19 As shown in the figure, a contact portion 6 for contacting with the object W may be separately arranged so that the contact portion 6 contacts the object W. Moreover, for example, by printing while contacting the contact portion 6 with a position of the object W that does not overlap with the printed area or with an area of ​​the printed area that has not been printed, it is possible to suppress contact with the ink I that is not completely dried. Therefore, higher quality printing can be performed. In addition, in the example shown in the figure, the contact portion 6 protrudes from the holding member 59, but the structure of the contact portion 6 is not particularly limited.

[0094] When the force sensor 7 detects that the first optical sensor 5A and the second optical sensor 5B are in contact with the object W, the first optical sensor 5A and the second optical sensor 5B are controlled to be slightly separated from the object W so that they are out of contact, thereby Fig. 20 As shown, the print head 3 can also be moved so as to draw the vicinity of the surface of the object W. According to such a method, the separation distance between the print head 3 and the object W can be further reduced, and the variation of the separation distance can be suppressed, so that higher quality printing can be performed.

[0095] As described above, the robot system 1 of this embodiment includes the force sensor 7 that detects contact with the object W. The detection result of the force sensor 7 can suppress the variation of the separation distance between the print head 3 and the object W, thereby enabling higher quality printing.

[0096] According to such a second embodiment, the same effects as those of the above-mentioned first embodiment can be achieved.

[0097] Third embodiment

[0098] Fig.21 It is an overall diagram of a robot system according to a third embodiment.

[0099] The robot system 1 according to the present embodiment is the same as the robot system 1 according to the first embodiment except that the conveyor belt 8 is used to convey the object W. In the following description, the robot system 1 according to the present embodiment is mainly described with the differences from the first embodiment, and the description of the same matters is omitted. In addition, in the drawings of the present embodiment, the same reference numerals are given to the same components as those in the above embodiment.

[0100] like Fig.21 As shown, the robot system 1 of the present embodiment 1 has a conveyor belt 8 for conveying an object W. In addition, a camera 81 is arranged just above the conveyor belt 8. The control device 9 uses the camera 81 to photograph the object W flowing on the conveyor belt 8, and detects the position of the object W on the conveyor belt 8 based on the image obtained thereby. In addition, the control device 9 predicts the time when the object W reaches the working area of ​​the robot 2 and the moving trajectory within the working area based on the position of the object W detected as described above and the conveying speed of the conveyor belt 8, and controls the driving of the robot 2 based on the prediction so that the printing head 3 moves along the printing track Q relative to the object W. In this way, by using the conveyor belt 8 to convey the object W, it becomes easy and smooth to supply the object W to the working area of ​​the robot 2. Therefore, the cycle time of the printing operation can be shortened.

[0101] As described above, the robot system 1 of this embodiment includes the conveyor belt 8 for conveying the object W, and uses the print head 3 to perform work on the object W conveyed by the conveyor belt 8. According to such a configuration, it becomes easy and smooth to supply the object W into the working area of ​​the robot 2. Therefore, the cycle time of the work can be shortened.

[0102] According to such a third embodiment as well, the same effects as those of the above-mentioned first embodiment can be achieved.

[0103] The robot system and position detection method of the present invention are described above based on the illustrated embodiments, but the present invention is not limited thereto, and the configuration or process of each part can be replaced by any configuration or process having the same function. In addition, other arbitrary configurations or processes may be added to the present invention. In addition, the various embodiments may be appropriately combined.

Claims

1. A robot system, characterized in that: have: Robotic arm; A tool, mounted on the robotic arm; a plurality of optical sensors arranged in a fixed relative positional relationship with the tool and detecting an amount of translation relative to the object; as well as The control device detects the translation amount and the rotation amount of the tool based on the translation amounts detected by the plurality of optical sensors, and detects the position of the tool based on the translation amount and the rotation amount of the tool.

2. The robot system according to claim 1, wherein: The optical sensor is an optical tracking sensor having: light source; a lens component for irradiating the light from the light source to the object; as well as an imaging element, receiving the light reflected by the object, The translation amount relative to the object is detected by comparing a plurality of images captured by the imaging element and calculating the movement amount of the images.

3. The robot system according to claim 2, wherein: The optical sensor irradiates the light toward the object from an oblique direction.

4. The robot system according to claim 1, wherein: The optical sensor has two detection axes that are orthogonal to each other.

5. The robot system according to claim 1, wherein: The tool is arranged between the plurality of optical sensors.

6. The robot system according to claim 1, wherein: The tool is a printing head, Then, a printing operation is performed on the object.

7. The robot system according to claim 6, wherein: The control device corrects a printing track of the printing head according to the position of the printing head.

8. The robot system according to claim 1, wherein: The robot system includes a force sensor that detects contact with the object.

9. The robot system according to claim 1, wherein: The robot system has a conveyor belt for conveying the object. The tool is used to perform work on the object conveyed by the conveyor belt.

10. A position detection method, characterized in that: have: A robot arm; a tool mounted on the robot arm; and a plurality of optical sensors arranged in a fixed relative position relationship with the tool and detecting a translation amount relative to an object, The position detection method detects the translation amount and the rotation amount of the tool based on the translation amounts detected by the plurality of optical sensors, and detects the position of the tool based on the translation amount and the rotation amount of the tool.

Images