PROCESSING SYSTEM, ROBOT SYSTEM, CONTROL DEVICE, TEACHING METHOD, AND STORAGE MEDIUM

According to one embodiment, a processing system teaches an operation to a robot. The robot includes a detector including detection elements arranged along first and second directions, and a manipulator to which the detector is mounted. The processing system performs position teaching processing. The position teaching processing includes causing the detector to perform a probe of a weld portion of a joined body. The probe includes a transmission of an ultrasonic wave and a detection of a reflected wave. The position teaching processing includes calculating a center position of the weld portion in a first plane based on first intensity data of an intensity of the reflected wave, setting a teaching point of the robot based on a first position of the detector, and moving the detector along the first plane to a second position, and setting the teaching point based on the second position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-118985, filed on Jul. 19, 2021; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a processing system, a robot system, a control device, a teaching method, a program, and a storage medium.

BACKGROUND

There is a robot that inspects a joined body. There is a need for technology that can more easily set teaching points for such a robot when inspecting.

DETAILED DESCRIPTION

According to one embodiment, a processing system teaches an operation to a robot. The robot includes a detector including a plurality of detection elements arranged along a first direction and a second direction, and a manipulator to which the detector is mounted. The second direction crosses the first direction. The processing system performs position teaching processing. The position teaching processing includes causing the detector to perform a probe of a weld portion of a joined body. The probe includes a transmission of an ultrasonic wave and a detection of a reflected wave. The position teaching processing includes calculating a center position of the weld portion in a first plane based on first intensity data of an intensity of the reflected wave obtained by the probe. The first plane is along the first and second directions. The position teaching processing includes setting a teaching point of the robot based on a first position of the detector in the first plane when a distance between the center position and the first position is not more than a first threshold. When the distance is greater than the first threshold, the position teaching processing includes moving the detector along the first plane to a second position to reduce the distance, and setting the teaching point based on the second position.

FIG.1is a schematic view showing a robot system according to an embodiment.

As shown inFIG.1, the robot system2according to the embodiment includes a processing system1and a robot20. The processing system1includes a control device10, an operation terminal11, and a processing device12. The processing system1teaches an operation to the robot20.

The control device10controls operations of the robot20. The control device10is a so-called robot controller. The control device10includes a control circuit, a servo controller, a power supply device, etc. The control device10controls operations of the robot20by controlling servo motors of each axis according to a prestored operation program, teaching data set by the operation terminal11, etc.

The operation terminal11is a terminal device for operating the robot20. The operation terminal11is a so-called teaching pendant. The operation terminal11is connected with the control device10and accepts input of the operation program of the robot20, input of settings, etc. For example, the control device10and the operation terminal11are connected via a wired cable, wireless communication, or a network. Also, the user uses the operation terminal11to modify, correct, or generate new teaching data, etc. Teaching data is data for teaching the operations of the robot20to the robot20.

The robot20includes a manipulator21, and a detector22mounted to the manipulator21. For example, the manipulator21is vertical articulated. The detector22is located at the distal end of the manipulator21as an end effector. The manipulator21may be horizontal articulated or parallel link. The manipulator21may include a combination of two or more selected from vertical articulated, horizontal articulated, and parallel link. It is favorable for the manipulator21to have not less than six degrees of freedom.

The detector22performs a probe (probing) of the object. The probe includes transmitting an ultrasonic wave toward the object and detecting (receiving) a reflected wave. The detector22acquires intensity data of the intensity of the reflected wave by the probe. The detector22transmits the intensity data to the processing device12connected with the control device10. For example, the control device10and the processing device12are connected via a wired cable, wireless communication, or a network.

In the example ofFIG.1, a dispenser25also is included as an end effector. The dispenser25dispenses a couplant liquid onto the surface of the object.

The object of the probe is a joined body joined by welding multiple members. The multiple members are joined at a weld portion. The processing device12processes intensity data and acquires data related to the weld portion. For example, the processing device12uses the intensity data to perform inspection processing of the weld portion. The robot system2performs the inspection processing for multiple joined bodies50of the same type.

FIG.2is a schematic view showing the structure of the detector and the joined body.

In the example ofFIG.2, the object of the probe by the detector22is the joined body50. The joined body50includes a metal plate51(a first member) and a metal plate52(a second member). The metal plate51and the metal plate52are joined at a weld portion53. In other words, a boundary between the metal plate51and the metal plate52does not exist at the weld portion53. A solidified portion54that is formed by mixing the melted metal exists at the weld portion53. The weld portion53is formed by resistance spot welding.

As shown inFIG.2, the detector22includes detection elements22a, a propagating part22b, a housing22c, and a sensor22d.

The detection elements22aare two-dimensionally arranged along an X-direction (a first direction) and a Y-direction (a second direction). The X-direction and the Y-direction cross each other. In the example, the Y-direction is perpendicular to the X-direction. For example, the detection element22ais a transducer that emits an ultrasonic wave of a frequency of not less than 1 MHz and not more than 100 MHz. The detection element22atransmits the ultrasonic wave along a Z-direction (a third direction). The Z-direction is perpendicular to the X-Y plane (a first plane).

The multiple detection elements22aare located at the distal end of the housing22cand are covered with the propagating part22b. The propagating part22bis positioned between the joined body50and the detection elements22awhen the detector22is caused to contact the joined body50. When the detection element22aemits an ultrasonic wave, the ultrasonic wave propagates through the propagating part22band is transmitted outside the detector22. When the ultrasonic wave is reflected, the reflected wave propagates through the propagating part22band reaches the detection elements22a.

The detection elements22adetect the reflected wave. The intensity of the signal detected by the detection elements22acorresponds to the intensity of the reflected wave. The detector22acquires signals (intensity data) indicating the reflected wave intensity and transmits the signals to the processing device12.

The propagating part22bincludes a resin material or the like through which the ultrasonic wave easily propagates. Deformation, damage, and the like of the detection elements22acan be suppressed by the propagating part22bwhen the detector22contacts the weld portion53. The propagating part22bhas a hardness sufficient to suppress the deformation, damage, and the like when contacting the weld portion53.

The sensor22dis mounted to the housing22cand detects contact of the detector22on the joined body50. The sensor22dis, for example, a force sensor, an acceleration sensor, an angular velocity sensor, a photointerrupter sensor, or a distance sensor.

A couplant liquid55is coated onto the surface of the joined body50so that the ultrasonic wave easily propagates between the detector22and the joined body50when probing. Each detection element22atransmits an ultrasonic wave US toward the joined body50on which the couplant liquid55is coated.

For example, as shown inFIG.2, one detection element22atransmits the ultrasonic wave US toward the joined body50. A portion of the ultrasonic wave US is reflected by the upper surface, lower surface, or the like of the joined body50. The multiple detection elements22aeach detect a reflected wave RW. In the probe, each detection element22asequentially transmits the ultrasonic wave US; and each reflected wave RW is detected by the multiple detection elements22a.

The processing device12uses the intensity data to perform various processing. For example, the processing device12inspects the weld portion53. The processing device12may identify the position of the weld portion53in the joined body50. The processing device12may calculate the center position of the weld portion53. The processing device12may calculate the diameter of the weld portion53.

FIGS.3A to3Care schematic views for describing operations of the processing system according to the embodiment.

As shown inFIG.3A, the ultrasonic wave US is reflected by the surface of the propagating part22b, an upper surface51aand a lower surface51bof the metal plate51, and an upper surface53aand a lower surface53bof the weld portion53.

The Z-direction positions of the surface of the propagating part22b, the upper surface51a, the upper surface53a, the lower surface51b, and the lower surface53bare different from each other. In other words, distances in the Z-direction between the detection element22aand these surfaces are different from each other. The detection element22adetects peaks of the reflected wave intensities when detecting the reflected waves from these surfaces. Which surface reflected the ultrasonic wave US can be discriminated by calculating the time until each peak is detected after transmitting the ultrasonic wave US.

FIGS.3B and3Care graphs illustrating the relationship between the time after transmitting the ultrasonic wave US and the intensity of the reflected wave RW at one point in the X-Y plane. InFIGS.3B and3C, the horizontal axis is the intensity of the detected reflected wave RW. The vertical axis is the elapsed time after transmitting the ultrasonic wave US. The time corresponds to the Z-direction position. The graph ofFIG.3Billustrates a detection result of the reflected waves RW from the surface of the propagating part22b, the upper surface51a, and the lower surface51b. In other words, the graph ofFIG.3Billustrates the detection result of the reflected waves RW from a point that is not joined. The graph ofFIG.3Cillustrates the detection result of the reflected waves RW from the surface of the propagating part22b, the upper surface53a, and the lower surface53b. In other words, the graph ofFIG.3Cillustrates the detection result of the reflected waves RW from a point that is joined.

In the graphs ofFIGS.3B and3C, a peak Pe10is based on the reflected wave RW from the surface of the propagating part22b. A peak Pe11is based on the reflected wave RW from the upper surface51a. A peak Pe12is based on the reflected wave RW from the lower surface51b. Times from the transmission of the ultrasonic wave US until the peak Pe11and the peak Pe12are detected correspond respectively to the Z-direction positions of the upper surface51aand the lower surface51b.

Similarly, a peak Pe13is based on the reflected wave RW from the upper surface53a. A peak Pe14is based on the reflected wave RW from the lower surface53b. The times from the transmission of the ultrasonic wave US until the peak Pe13and the peak Pe14are detected correspond respectively to the Z-direction positions of the upper surface53aand the lower surface53b.

The processing device12determines whether or not the peak Pe12exists in the Z-direction reflected wave intensity distribution at points in the X-Y plane. Specifically, the processing device12detects a peak in a range in the Z-direction in which the peak Pe12may be detected. The processing device12compares the peak intensity to a threshold. The threshold and the range in the Z-direction are preset.

When the peak intensity is greater than the threshold, the processing device12determines that the peak is the peak Pe12. The existence of the peak Pe12indicates that the lower surface51bexists at the point and that the metal plate51and the metal plate52are not joined. The processing device12determines that points at which the peak Pe12is detected are not joined. The processing device12determines that points at which the peak Pe12is not detected are joined. The processing device12sequentially determines whether or not each of multiple points in the X-Y plane are joined. The processing device12identifies a cluster of points determined to be joined as the weld portion53.

For example, in the inspection processing, the processing device12identifies the weld portion53and calculates the diameter of the weld portion53. The processing device12compares the diameter to a preset threshold. The processing device12determines the weld portion53to pass when the diameter is greater than the threshold. The processing device12determines the weld portion53to fail when the diameter is not more than the threshold. The diameter that is compared to the threshold is the major diameter or the minor diameter of the weld portion53.

In the examples ofFIGS.3B and3C, the intensity of the reflected wave RW is expressed as an absolute value. The intensity of the reflected wave may be expressed in any form. For example, the reflected wave intensity that is output from the detection element22aincludes positive values and negative values according to the phase. Various processing may be performed based on the reflected wave intensity including positive values and negative values. The reflected wave intensity that includes positive values and negative values may be converted into absolute values. The average value of the reflected wave intensities may be subtracted from the reflected wave intensity at each time. Or, the weighted average value, the weighted moving average value, etc., of the reflected wave intensities may be subtracted from the reflected wave intensity at each time. Filtering may be performed to extract only a frequency component of a specific period. The various processing described in the application can be performed even when the results of such processing applied to the reflected wave intensity are used.

FIG.4is a schematic view illustrating intensity data obtained by the probe.

In the probe as described above, each detection element22asequentially transmits an ultrasonic wave; and each reflected wave is detected by the multiple detection elements22a. In the specific example shown inFIGS.2, 8×8, i.e., sixty-four detection elements22aare provided. In such a case, the sixty-four detection elements22asequentially transmit ultrasonic waves. One detection element22arepeatedly detects the reflected wave 64 times. The detection result of the Z-direction reflected wave intensity distribution is output 64 times from one detection element22a. The intensity distribution of the sixty-four reflected waves output from the one detection element22aare summed. The summed intensity distribution is used as the intensity distribution at the coordinate at which the one detection element22ais located in one probe. Similar processing is performed for the detection results of the sixty-four detection elements22a. Aperture synthesis may be performed to increase the resolution in the X-direction and the Y-direction of the detection results of the detection elements22a. The reflected wave intensity distribution in the Z-direction is generated at each of multiple points in the X-Y plane (the first plane) by the processing described above. In other words, three-dimensional intensity data that includes the reflected wave intensity at points in the X-direction, the Y-direction, and the Z-direction is obtained.

FIG.4schematically shows a three-dimensional intensity distribution. The schematic view ofFIG.4shows the weld portion53vicinity of the three-dimensional intensity data. InFIG.4, portions at which the luminance is high are portions at which the reflected wave intensity of the ultrasonic wave is relatively large. In the example ofFIG.4, reflected waves from the upper surface and the lower surface of the weld portion53and reflected waves of multiple reflections between the upper surface and the lower surface appear.

When obtaining data related to the weld portion in the inspection processing, the control device10operates the manipulator21so that the distal end of the detector22contacts the weld portion53. When performing the probe in the inspection processing, the orientation and the position of the distal end of the detector22are preset as a teaching point. The position and orientation of another portion corresponding to the position and orientation of the distal end of the detector22may be set as the teaching point. In such a case as well, the position and orientation of the distal end of the detector22can be considered to be set as the teaching point.

The control device10operates the manipulator21according to an operation program to set the position and orientation of the distal end of the detector22to the position and orientation of the teaching point. Specifically, the control device10acquires data of the rotation angles of the actuators from encoders included at the joints of the manipulator21. The control device10generates a control signal based on the stored teaching point and the acquired data. The control device10transmits the generated control signal to the robot20and moves the manipulator21by operating the actuators.

The processing system1according to the embodiment teaches an operation to the robot20. The processing system1can be utilized to set the teaching point of the robot20. The processing system1sets the teaching point by using the intensity data transmitted from the detector22.

FIG.5is a flowchart showing a teaching method according to the embodiment.

The user causes the distal end of the detector22to approach the weld portion53. A couplant liquid is coated onto the weld portion53. The detector22contacts the weld portion53(step S1). For example, the user moves the manipulator21by hand or by the operation terminal11and causes the distal end of the detector22to contact the weld portion53. Or, after the user causes the detector22to approach the weld portion53, the control device10may cause the detector22to contact the weld portion53by moving the manipulator21. The processing system1performs position teaching processing (step S10).

In the position teaching processing, the processing device12causes the detector22to perform a probe in a state in which the detector22contacts the weld portion53(step S11). The detector22acquires intensity data (first intensity data) of the intensity of the reflected wave by the probe (step S12). The processing device12receives the intensity data from the detector22. The processing device12calculates the center position of the weld portion53in the X-Y plane based on the intensity data (step S13). The processing device12transmits the center position to the control device10. The control device10refers to the position (a first position) in the X-Y plane of the detector22. The control device10compares the distance between the first position and the received center position to a preset threshold (a first threshold) (step S14).

For example, the position in the X-Y plane of the detector22corresponds to the center position in the X-Y plane of the intensity data. In such a case, the center position of the weld portion53calculated based on the intensity data corresponds to the distance between the center position of the weld portion53and the center position in the X-Y plane of the intensity data. Therefore, in step S14, the control device10compares the received center position of the weld portion53to the preset threshold (the first threshold).

When the distance is not more than the threshold, the control device10sets a teaching point based on the first position (step S15). For example, the control device10sets the first position as the position of the teaching point. The control device10may set a position obtained by a calculation performed on the first position as the position of the teaching point.

When the distance is greater than the threshold, the control device10moves the detector22along the X-Y plane to reduce the distance (step S16). At this time, the control device10may move the detector22away from the joined body50to avoid friction between the detector22and the joined body50. After moving the detector22away from the joined body50, the control device10moves the detector22along the X-Y plane. Subsequently, the control device10causes the detector22to contact the joined body50.

The control device10refers to the position (a second position) in the X-Y plane of the detector22after moving. The control device10sets the teaching point based on the second position (step S17). For example, the control device10sets the second position as the position of the teaching point. The control device10may set a position obtained by a calculation performed on the second position as the position of the teaching point.

The control device10may re-perform step S14after step S16. In such a case, the distance between the center position and the position of the detector22is re-compared to the threshold. Step S16is repeated until the distance equals the threshold or less. The position of the teaching point can be set more appropriately thereby. The control device10stores the set teaching point (step S18).

The XYZ coordinate system shown inFIG.2may be different from the robot coordinate system used to express the teaching point. The control device10or the processing device12may convert the center position calculated in step S13into the robot coordinate system as appropriate. When setting the teaching point, the control device10or the processing device12may convert the position in the X-Y plane of the detector22into the robot coordinate system as appropriate.

The method for calculating the center position of the weld portion53in the teaching method described above will now be described. The center position can be calculated using any of the following methods.

FIGS.6A to6Care schematic views showing a reflected wave intensity distribution obtained by processing the intensity data.

The processing device12acquires the data shown inFIGS.6A to6Cby processing the intensity data.FIG.6Ashows the reflected wave intensity distribution in the X-Y plane at the weld portion53vicinity.FIG.6Bshows the reflected wave intensity distribution in the Y-Z plane at the weld portion53vicinity.FIG.6Cshows the reflected wave intensity distribution in the X-Z plane at the weld portion53vicinity.

The data ofFIG.6Ais obtained by summing the intensity in the Z-direction at each point in the X-Y plane. The data ofFIG.6Bis obtained by summing the intensity in the X-direction at each point in the Z-direction. The data ofFIG.6Cis obtained by summing the intensity in the Y-direction at each point in the Z-direction.FIGS.6A to6Cshow schematically binarized intensities of the reflected waves. The white points indicate that the intensity of the reflected wave is relatively high at those points. The black points indicate that the intensity of the reflected wave is relatively low at those points.

For example, the processing device12calculates the centroid position of the intensity as the center position of the weld portion53for the reflected wave intensity distribution in the X-Y plane shown inFIG.6A. For example, as shown inFIG.6A, the luminous centroid position of the binarized image may be calculated. Or, the luminous centroid position may be calculated for an image in which each pixel has a pixel value of one of three or more levels (e.g., 0 to 255).

Or, the processing device12may calculate the centroid position by extracting the reflected wave component from the weld portion53in the Z-direction. For example, as shown inFIGS.6B and6C, the period at which the reflected wave from the weld portion53is detected is different from the period at which the reflected waves from other portions are detected. The processing device12filters the intensity distribution in the Z-direction by using a preset thickness of the weld portion53. Thereby, the processing device12extracts the reflected wave component from the weld portion53. The processing device12calculates the centroid position of the intensity distribution in the X-Y plane after filtering as the center position of the weld portion53.

Or, the processing device12may identify the weld portion53and calculate the center position based on the identified weld portion53.

FIG.7is a schematic view illustrating the identified weld portion.

FIG.7shows the result of determining a joint or non-joint at each of multiple points in the X-Y plane in which the probe is performed. The ranges in the X-direction and the Y-direction of the region in which the determination of the joint or non-joint is performed correspond to the range in the X-direction and the Y-direction in which the intensity data is obtained. As an example, the range in the X-direction and the range in the Y-direction of the two-dimensional data shown inFIG.7correspond respectively to the range in the X-direction and the range in the Y-direction of the three-dimensional intensity data shown inFIG.4. A portion of the range in the X-direction and the Y-direction in which the intensity data is obtained may be extracted, and the determination of the joint or non-joint may be performed for the extracted region. InFIG.7, the points that are determined to be joined based on the intensity data are illustrated using white. The points that are determined not to be joined are illustrated using black. A cluster of points determined to be joined is identified as the weld portion53. The processing device12uses the determination result of the joining at the points to generate the two-dimensional data shown inFIG.7.

The processing device12may calculate the centroid position in the X-Y plane of the identified weld portion53as the center position of the weld portion53. As described above, the weld portion53can be identified by determining the joint or non-joint at each point in the X-Y plane. The processing device12may calculate the center of a circle that inscribes or circumscribes the identified weld portion53in the X-Y plane as the center position of the weld portion53.

When the teaching point has been set, thereafter, the robot system2uses the teaching point to perform the inspection processing. For example, the robot system2refers to the teaching point and performs the inspection processing for the weld portion53of another joined body50. When performing the inspection processing, the control device10moves the manipulator21and sets the position and orientation of the distal end of the detector22to the position and orientation of the teaching point.

When multiple weld portions53are formed in one joined body50, the teaching point is set for each weld portion53. After the multiple teaching points are set, the inspection processing is performed for the multiple weld portions53of another joined body50.

Advantages of the embodiment will now be described.

To automatically inspect the joined body50by using the manipulator21, it is necessary to pre-teach the position and orientation of the detector22when inspecting. The taught operation is performed by a teaching playback method. The following is a teaching method according to a reference example. The user of the robot20prepares the joined body50. The user checks the weld portion53of the joined body50with the naked eye. The user moves the manipulator21by hand or by the operation terminal11and causes the distal end of the detector22to contact the center of the weld portion53. The control device10sets the position and orientation of the distal end of the detector22at this time as a teaching point.

To cause the distal end of the detector22to contact the center of the weld portion53, it is necessary to finely adjust the position of the detector22. A long period of time is necessary to set the teaching point when the user is inexperienced at the task. Also, fluctuation occurs in the taught position. When teaching, there is also a possibility that the detector22may be damaged by contact of the detector22with the joined body50. Also, a weld mark exists at the position at which the weld portion53is formed. The user considers the center of the weld mark to be the center of the weld portion53and causes the detector22to contact the center of the weld mark. However, there are cases where the center of the weld mark deviates from the actual center of the weld portion53. When the position of the detector22deviates from the center of the weld portion53, the accuracy of the inspection may decrease. Therefore, technology that can more easily set the center of the weld portion53as the teaching point is desirable.

For this problem, in the processing system1according to the embodiment, position teaching processing is performed. In the position teaching processing, it is automatically determined whether or not the position of the detector22deviates from the center position of the weld portion53based on the intensity data obtained by the probe. When the position of the detector22deviates from the center position of the weld portion53, the processing system1controls the manipulator21so that the detector22approaches the center position of the weld portion53. It is therefore unnecessary for the user to adjust the position of the detector22. The fluctuation of the taught position also can be suppressed. Damage of the detector22when teaching can be suppressed. Also, the position of the detector22can be aligned with the center position of a weld portion53that cannot be checked by the naked eye of the user. According to the embodiment, the center position of the weld portion53can be more easily set as the teaching point.

First Modification

FIG.8is a flowchart showing a teaching method according to a first modification of the embodiment.

The orientation of the detector22affects the intensity data obtained by the probe. It is favorable for the orientation of the detector22to be perpendicular to the surface of the weld portion53. As shown inFIG.8, the processing system1may perform orientation teaching processing (step S20) in addition to the position teaching processing (step S10).

In the orientation teaching processing, the processing device12causes the detector22to perform the probe in a state in which the detector22contacts the weld portion (step S21). The detector22acquires intensity data (second intensity data) of the intensity of the reflected wave by the probe (step S22). Based on the intensity data, the processing device12calculates how much the orientation (a first orientation) of the detector22when probing is tilted with respect to the weld portion53(step S23). The processing device12transmits the calculated tilt to the control device10. The control device10compares the tilt to a preset threshold (a second threshold) (step S24).

When the tilt is not more than the threshold, the control device10sets the orientation of the teaching point based on the first orientation (step S25). For example, the control device10sets the first orientation as the orientation of the teaching point. The control device10may set an orientation obtained by a calculation performed on the first orientation as the orientation of the teaching point.

When the tilt is greater than the threshold, the control device10rotates the detector22around the X-direction or the Y-direction to reduce the tilt (step S26). For example, the distal end of the detector22is set to the rotation center. The control device10refers to the orientation (the second orientation) of the detector22after rotating. The control device10sets the orientation of the teaching point based on the second orientation (step S27). For example, the control device10sets the second orientation as the orientation of the teaching point. The control device10may set an orientation obtained by a calculation performed on the second orientation as the orientation of the teaching point.

The control device10may re-perform step S24after step S26. In such a case, the tilt is re-compared to the threshold. Step S26is repeated until the tilt becomes the threshold or less. The orientation of the teaching point can be set more appropriately thereby. The control device10stores the teaching point that is set (step S28).

FIG.9is a schematic view showing the detector.

For example, the orientation corresponds to a direction D1of the detector22shown inFIG.9. The direction D1is perpendicular to the arrangement directions of the multiple detection elements22a. The tilt is represented by an angle θx around the X-direction and an angle θy around the Y-direction between the direction D1of the detector22and a normal direction D2of the weld portion53.

The angle that represents the orientation shown inFIG.8may be different from an angle in the robot coordinate system used to express the teaching point. The control device10or the processing device12may convert the tilt calculated in step S23into the robot coordinate system as appropriate. When setting the teaching point, the control device10or the processing device12may convert the angle representing the orientation of the detector22into an angle in the robot coordinate system as appropriate.

FIGS.10A to10Care examples of images obtained in the inspection.

A method for calculating the tilt will now be described.FIG.10Ais an image of the reflected wave intensity distribution in the X-Y plane at the weld portion53vicinity.FIG.10Bis an image of the reflected wave intensity distribution in the Y-Z plane at the weld portion53vicinity.FIG.10Cis an image of the reflected wave intensity distribution in the X-Z plane at the weld portion53vicinity. In the images ofFIGS.10A to10C, the luminance corresponds to the intensity of the reflected wave. In other words, a brighter pixel color indicates that the reflected wave intensity is high at that point.

As shown inFIG.10B, the angle θx is calculated based on the detection result in the Y-Z plane. As shown inFIG.10C, the angle θy is calculated based on the detection result in the X-Z plane. Specifically, the processing device12calculates the average of the three-dimensional luminance gradients. The processing device12uses the average of the gradients around the X-direction as the angle θx. The processing device12uses the average of the gradients around the Y-direction as the angle θy.

The orientation teaching processing may be performed before the position teaching processing or may be performed after the position teaching processing. The position teaching processing and the orientation teaching processing may be performed based on the result of one probe.

Favorably, the orientation teaching processing is performed after the position teaching processing. When the center position of the weld portion53deviates from the position of the detector22and the detector22is tilted with respect to the weld portion53, there is a possibility that multiple-reflection waves from the weld portion53may be undetected by the detector22as shown inFIG.11A. Multiple-reflection waves are reflected waves detected at deep Z-direction positions. When multiple-reflection waves are not detected, the accuracy of the calculated orientation of the detector22may decrease. By performing the position teaching processing before the orientation teaching processing, the multiple-reflection waves from the weld portion53are more easily detected as shown inFIG.11B. Thereby, the orientation of the detector22can be calculated with higher accuracy.

Second Modification

FIG.12is a flowchart showing a teaching method according to a second modification of the embodiment.FIGS.13A and13Bare schematic views for describing the teaching method according to the second modification of the embodiment.

Compared to the teaching method shown inFIG.5, the teaching method according to the second modification includes step S19instead of step S1. Also, the teaching method according to the second modification includes steps S15aand S17ainstead of steps S15and S17.

In step S19, the processing system1sets the distance in the Z-direction between the detector22and the weld portion53to a first distance. The first distance is greater than a second distance in the Z-direction between the detector22and the weld portion53when the inspection processing is performed. At this time, as shown inFIG.13A, the detector22contacts the joined body50via the couplant liquid55. The detector22does not directly contact the joined body50.

Subsequently, similarly to the teaching method shown inFIG.5, the processing system1performs steps S11to S14. In step S15a, the processing system1sets the teaching point based on the first position. At this time, the control device10sets the distance in the Z-direction between the detector22and the weld portion53to the second distance. Thereby, the detector22approaches the weld portion53. For example, as shown inFIG.13B, the detector22directly contacts the joined body50. The processing system1sets the teaching point based on the first position in the X-Y plane and the Z-direction position of the detector22after the approach of the detector22.

Similarly, in step S17a, the processing system1sets the teaching point based on the second position. At this time, the control device10sets the distance in the Z-direction between the detector22and the weld portion53to the second distance. The processing system1sets the teaching point based on the second position in the X-Y plane and the Z-direction position of the detector22after approaching.

The first distance can be set by causing the detector22to approach the joined body50while performing the probe. When the detector22is separated from the joined body50and the couplant liquid55, the ultrasonic wave is attenuated, and the reflected wave is not detected. When the detector22contacts the couplant liquid55, the ultrasonic wave propagates through the couplant liquid55; and the reflected wave is detected. The control device10causes the detector22to gradually approach the joined body50, and stops the detector22at the timing at which a reflected wave is detected. Thereby, the distance between the detector22and the joined body50is set to the first distance.

Or, the first distance may be set by moving the detector22slightly away from the joined body50after causing the detector22to contact the joined body50. The control device10causes the detector22to approach the joined body50until contact of the detector22with the joined body50is detected by the sensor22d. After the contact is detected, the control device10moves the detector22slightly away from the joined body50. The distance to be moved away is preset. Thereby, the distance between the detector22and the joined body50is set to the first distance.

After contact is detected, the detector22may be gradually moved away from the joined body50while probing. The control device10gradually moves the detector22away from the joined body50while the reflected wave is detected. When the reflected wave is no longer detected, the control device10moves the detector22to the Z-direction position at which the reflected wave was lastly detected. Thereby, the distance between the detector22and the joined body50is set to the first distance.

When performing step S16, the distance in the Z-direction between the detector22and the weld portion53is set to the first distance. In other words, when performing step S16, the control device10moves the detector22along the X-Y plane without moving the detector22away from the weld portion53. At this time, the detector22contacts the joined body50via the couplant liquid. Therefore, the friction between the detector22and the joined body50when moving the detector22can be reduced. Also, the time necessary for performing the teaching method can be reduced because the operation of moving the detector22away from the weld portion53is unnecessary.

In the teaching method according to the second modification, the orientation teaching processing also may be performed similarly to the first modification. As described above, it is favorable for the orientation teaching processing to be performed after the position teaching processing.

FIG.14is a flowchart showing inspection processing according to the embodiment.

When the teaching point has been set by any of the teaching methods described above, the robot system2performs inspection processing (step S30). The control device10dispenses the couplant liquid55from the dispenser25toward the joined body50(step S31). The control device10operates the manipulator21and sets the position and orientation of the detector22to the position and orientation of the teaching point (step S32). The control device10causes the detector22to perform a probe of the weld portion53(step S33). The processing device12identifies the weld portion53based on the obtained intensity data (third intensity data) (step S34). The processing device12inspects the weld portion53(step S35). In the inspection, for example, the diameter of the weld portion53is compared to a threshold. The processing device12stores the inspection result (step S36).

According to the processing method that includes the teaching method and the inspection processing, the center position of the weld portion53can be more easily set as the teaching point; and the weld portion53can be inspected using the teaching point that is set.

FIG.15is a schematic view showing the structure of another detector.

In an example described above, the couplant liquid55is used when performing the probe. The couplant liquid55is omissible if a propagating member that is deformable according to the shape of the weld portion53is included in the detector.

The detector23shown inFIG.15includes a first propagating member22b1and a second propagating member22b2. The first propagating member22b1is mounted to the housing22cof the detector23. The ultrasonic wave can propagate through the first propagating member22b1. For example, the first propagating member22b1contacts the multiple detection elements22a. Or, another member capable of propagating the ultrasonic wave may be located between the first propagating member22b1and the multiple detection elements22a.

The second propagating member22b2is mounted to the first propagating member22b1. The second propagating member22b2may be bonded to the first propagating member22b1or may be fixed with respect to the first propagating member22b1by a not-illustrated fixture. The first propagating member22b1is positioned between the second propagating member22b2and the multiple detection elements22a. The second propagating member22b2can propagate the ultrasonic wave. The ultrasonic wave that propagates through the first propagating member22b1propagates through the second propagating member22b2and is transmitted outside the detector23.

The first propagating member22b1is a solid. The first propagating member22b1has a sufficient hardness so that substantial modification does not occur even when operating the detector22. The second propagating member22b2is a gel but is not a liquid. The second propagating member22b2is softer than the first propagating member22b1. In other words, the hardness of the second propagating member22b2is less than the hardness of the first propagating member22b1. Therefore, the second propagating member22b2deforms easily compared to the first propagating member22b1. The first propagating member22b1has sufficient softness so that the first propagating member22b1can deform according to the surface configuration of the object of the inspection when probing.

The first propagating member22b1and the second propagating member22b2include resins. As one specific example, the first propagating member22b1includes acrylic. The second propagating member22b2includes segmented polyurethane. The acoustic impedance of a general steel plate used in joining is about 4.5×107(Pas/m). It is favorable for the acoustic impedances of the first and second propagating members22b1and22b2each to be greater than 1.0×105(Pas/m) and less than 1.0×108(Pas/m) so that the ultrasonic wave sufficiently propagates between the detector22and the joined body50. The acoustic impedance can be measured in accordance with JIS A 1405-1 (ISO 10534-1).

The processing system1may perform the teaching method described above for the robot20that includes the detector23instead of the detector22. However, it is favorable for the control device10to move the detector23away from the joined body50when moving the detector23along the X-Y plane in step S16of any of the teaching methods. Because the second propagating member22b2is a gel, the friction between the second propagating member22b2and the joined body50is large. The second propagating member22b2may be damaged when the detector22is moved in a state in which the second propagating member22b2contacts the joined body50. By moving the detector23along the X-Y plane after moving the detector23away from the joined body50, the damage of the second propagating member22b2can be suppressed.

FIG.16is a schematic view showing a hardware configuration.

The control device10, the operation terminal11, and the processing device12each include, for example, the configuration of a computer90shown inFIG.16. The computer90includes a CPU91, ROM92, RAM93, a memory device94, an input interface95, an output interface96, and a communication interface97.

The ROM92stores programs that control the operations of the computer90. Programs that are necessary for causing the computer90to realize the processing described above are stored in the ROM92. The RAM93functions as a memory region into which the programs stored in the ROM92are loaded.

The CPU91includes a processing circuit. The CPU91uses the RAM93as work memory to execute the programs stored in at least one of the ROM92or the memory device94. When executing the programs, the CPU91executes various processing by controlling configurations via a system bus98.

The memory device94stores data necessary for executing the programs and/or data obtained by executing the programs.

The output interface (I/F)96connects the computer90and an output device96a. The output I/F96is, for example, an image output interface such as Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI (registered trademark)), etc. The CPU91can transmit data to the output device96avia the output I/F96and cause the output device96ato display an image.

The communication interface (I/F)97connects the computer90and a server97athat is outside the computer90. The communication I/F97is, for example, a network card such as a LAN card, etc. The CPU91can read various data from the server97avia the communication I/F97.

The memory device94includes at least one selected from a hard disk drive (HDD) and a solid state drive (SSD). The input device95aincludes at least one selected from a mouse, a keyboard, a microphone (audio input), and a touchpad. The output device96aincludes at least one selected from a monitor and a projector. A device such as a touch panel that functions as both the input device95aand the output device96amay be used.

The functions of the control device10and the processing device12may be realized by the collaboration of three or more computers. The functions of the control device10and the processing device12may be realized by one computer. The major parts of the various processing described above are modifiable as appropriate between the control device10and the processing device12.

The processing of the various data described above may be recorded, as a program that can be executed by a computer, in a magnetic disk (a flexible disk, a hard disk, etc.), an optical disk (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD±R, DVD±RW, etc.), semiconductor memory, or another non-transitory computer-readable storage medium.

For example, the information that is recorded in the recording medium can be read by a computer (or an embedded system). The recording format (the storage format) of the recording medium is arbitrary. For example, the computer reads the program from the recording medium and causes the CPU to execute the instructions recited in the program based on the program. In the computer, the acquisition (or the reading) of the program may be performed via a network.

According to the processing system, the robot system, the control device, the teaching method, or the processing method described above, the center position of the weld portion can be more easily set as the teaching point. The center position of the weld portion can be more easily set as the teaching point by using a program to cause a computer to perform the teaching method or the processing method.