JP2020203308A - Control device, program, and robot control system - Google Patents

Abstract

To provide a control device that can enhance accuracy in determining an abnormality of welding, a program and a robot control system.SOLUTION: A control device comprises: a correction part that determines a corrected value to a command value of a welding parameter, using ranging data acquired from a laser sensor or groove information on an object to be welded based on image information acquired from a photographing device; an adjustment part that adjusts a threshold which is used for determining an abnormality of welding, using the corrected value; an abnormality determination part that determines an abnormality of welding, using the adjusted threshold and a measured value of the welding parameter; and an output part that outputs a determined result of the abnormality.SELECTED DRAWING: Figure 1

Description

The present invention relates to control devices, programs, and robot control systems.

Conventionally, various methods have been proposed as a method for detecting welding abnormalities in arc welding. For example, Patent Document 1 describes an arc welding quality determination system capable of setting a more appropriate threshold of physical quantity as compared with welding current and welding voltage by estimating a physical quantity different from welding current and welding voltage. It is disclosed. Further, Patent Document 2 discloses that the welding current is increased or decreased to a predetermined welding current according to groove information such as a gap in a welded portion due to poor accuracy of the work.

Japanese Unexamined Patent Publication No. 2016-26877 JP-A-2009-6383

In the prior art including Patent Document 1, the threshold value is set using the values of welding parameters such as the welding current, the welding voltage, and the physical quantity measured in the normal state. Once this threshold is set, the same threshold is used each time in the same weld section.

Further, in the technique described in Patent Document 1, the command value of the welding current is adaptively changed according to the groove information to set an appropriate welding current value, but when determining a welding abnormality, the welding current value is set. , As in the above-mentioned conventional technique, the threshold value once set is used as it is. Therefore, even though the welding current command value (current command value) is adaptively adjusted, the preset threshold value for the pre-adjustment current command value is used as it is, so that the adjusted normal welding current is used. Even if it is the measured value of, it may be determined that the welding is abnormal.

Therefore, an object of the present invention is to provide a control device, a program, and a robot control system capable of improving the accuracy of welding abnormality determination.

The control device according to one aspect of the present invention uses the groove information of the welding target based on the ranging data acquired from the laser sensor or the image information acquired from the imaging device to correct the command value of the welding parameter. Welding abnormality determination is performed using the correction unit to be determined, the adjustment unit that adjusts the threshold used for welding abnormality determination based on the correction value, the adjusted threshold value, and the measured value of the welding parameter. It includes an abnormality determination unit and an output unit that outputs the result of the abnormality determination.

According to this aspect, the threshold value used for determining the welding abnormality is also adaptively adjusted in response to the correction value adaptively adjusted with respect to the command value of the welding parameter. Therefore, the command of the welding parameter after adjustment is performed. It is possible to determine welding abnormalities by using a threshold value suitable for the value, and it is possible to improve the accuracy of determining welding abnormalities.

In the above aspect, when the section to be welded is further provided with a pre-determination unit for determining whether or not a threshold value used for welding abnormality determination is set, and it is determined that the section is a section in which the threshold value is set. In addition, the adjusting unit may perform adjustment processing of the threshold value used for determining the abnormality of welding.

As a result, the welding target section includes a section in which the threshold value is set in advance and a section in which the threshold value is not set, but the threshold value is adaptively changed for the section in which the threshold value is set in advance. At the same time, since welding abnormality is determined, it is possible to improve the accuracy of welding abnormality determination.

In the above aspect, even if the correction unit determines the correction value based on the correction information in which each value of the parameter related to the abnormality of the work shape and each correction value corresponding to each value are associated with each other. Good. For example, a correspondence table (correction information) is used, which includes gaps, steps, and the like as parameters related to the abnormality of the work shape, and the correction values are associated with the values of the respective parameters. The correction unit specifies the value of this parameter (for example, the value of a gap or a step) based on the groove information, and determines the correction value corresponding to the value of this parameter with reference to the corresponding table.

As a result, a correction value is set in advance for an abnormality in the work shape that may occur in the section to be welded, and an appropriate correction value is used according to the abnormality in the work shape to determine the command value of the welding parameter. Therefore, it is possible to improve the accuracy of welding abnormality determination because the welding abnormality is determined while improving the welding accuracy and the threshold value is adaptively changed.

According to the present invention, it is possible to provide a control device, a program, and a robot control system capable of improving the determination accuracy of welding abnormality.

It is a figure which shows an example of the schematic structure of the robot control system 1 provided with the arc welding abnormality determination system which concerns on embodiment. It is a block diagram which shows an example of the function of the welding control unit 213 and the processing unit 214 used for the arc welding abnormality determination processing which concerns on embodiment. It is a figure explaining the normality or abnormality of the work shape which concerns on embodiment. It is a figure which shows an example of the relationship between the welding current and the threshold value in the predetermined welding section which concerns on embodiment. It is a figure which shows an example of the predetermined welding section which concerns on embodiment. It is a figure which shows an example of the command value after correction with respect to the welding current when the work shape which concerns on embodiment are abnormal. It is a figure which shows the relationship between the gap G which shows the gap which concerns on embodiment, and the welding time. It is a figure which shows an example of the adaptive welding condition table which shows the relationship between the gap and the correction value which concerns on embodiment. It is a figure which shows an example of the adjustment of the threshold value which concerns on embodiment. It is a flowchart which shows an example of the abnormality determination procedure which concerns on embodiment.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those having the same reference numerals have the same or similar configurations.

<Overall configuration>
FIG. 1 is a diagram showing an example of a schematic configuration of a robot control system 1 including an arc welding abnormality determination system according to an embodiment of the present invention. FIG. 1 is also a diagram including an example of a functional block of the robot control system 1. The robot control system 1 performs arc welding (hereinafter, also simply referred to as “welding”) on the work W by a program-controlled articulated robot. The robot control system 1 includes a robot (for example, a manipulator) 10, a robot control device 20, an input / output terminal 30, a welding machine 40 including a welding power supply, a laser sensor LS, and a sensor control device 15. The robot control device 20 and the robot 10 have a minimum configuration of the "robot control system" disclosed, but include at least one of an input / output terminal 30, a welding machine 40, a laser sensor LS, and a sensor control device 15. A "control system" may be configured. The robot control device 20 and the input / output terminal 30 may be integrally configured with each other, or may be separately configured with each other as shown in FIG.

The robot control system 1 includes, for example, various cables for connecting the robot control device 20 and various devices to each other, and the robot control device 20 communicates with the various devices. The robot control system 1 also includes a power cable or the like for supplying a high-voltage welding voltage Vs between the welding wire 14 and the work W, which will be described later.

(Robot 10)
The robot 10 performs arc welding on the work W under the control of the robot control device 20, the input / output terminal 30, and the welding machine 40. The robot 10 includes a robot motor 101 controlled by a movement command output by the servo control unit 23. The movement of the articulated arm is controlled by driving the robot motor 101. Further, the robot 10 has a welding torch 13 connected to the tip of the articulated arm, a wire feeding device fixed to the articulated arm and the like, and a workbench 11.

One end (tip) of the articulated arm is connected to the welding torch 13, and the welding wire 14 as a filler material is exposed at the tip of the welding torch 13. The welding torch 13 generates an arc between the tip of the welding wire 14 and the work W, and melts the welding wire 14 and the work W with the heat of the arc to perform arc welding on the work W. is there. The welding torch 13 has a contact tip (not shown) electrically connected to the cable. The contact tip (hereinafter, also referred to as “chip”) is configured to supply the welding voltage Vs supplied from the cable to the welding wire 14. Due to the wear of the contact tip, the measured value of the welding parameter, which will be described later, fluctuates so as to be different from the measured value immediately after replacement.

(Laser sensor LS)
The laser sensor LS is a means for measuring the shape of the work W by emitting and receiving light from the laser, and is, for example, a scanning type laser sensor for measuring the distance to the work W. For example, the laser sensor LS is mounted on the welding torch 13 and measures the distance of the open groove portion (that is, the unwelded portion) on the side in the direction in which the welding torch 13 travels along the welding line. The laser sensor LS includes a light emitting unit that emits light toward the work W, a light receiving unit that receives the laser reflected by the work W, and the like (both not shown). The laser emitted by the light emitting unit is diffusely reflected by the work W and received by the light receiving unit. The light receiving unit is composed of, for example, a CCD line sensor, and measures the distance from the position of the center of gravity of the light receiving amount distribution to the work W.

(Sensor control device 15)
The sensor control device 15 drives and controls the laser sensor LS, and in the process of obtaining the target position (target coordinates) of the welding torch 13, the gap amount, groove area, cross-sectional shape, etc. from the distance measurement data (distance information) measured. Calculate the groove information including at least one of the above in real time. The sensor control device 15 transmits the groove information including the cross-sectional shape of the welded joint to the robot control device 20 as well as the transmission of the target position (target coordinates). The groove information referred to here means shape information between the base materials to be welded, and it is not always necessary that there are grooves between the base materials. For example, butt welding without grooves, fillet welding, etc. Information including the shape between the base materials. Since the sensor control device 15 only needs to be able to detect a shape defect of the welding target, information such as a gap generated between the base materials due to inaccuracies or heat shrinkage of the base material even if there is no groove between the base materials. Will be included in the destination information.

The sensor control device 15 includes a central processing unit (CPU), a plurality of image analysis programs prepared according to various groove shapes, a memory for storing various data, and the like. The sensor control device 15 corresponds to a means for acquiring groove information. The sensor control device 15 acquires groove information including the feature points and physical quantities (gap amount according to the groove, groove angle, groove area, etc.) by image analysis, and connects the acquired feature points. As a result, a three-dimensional trajectory of the welding torch 13 is generated.

In the generated three-dimensional orbit, the tangent vector is defined as the traveling direction vector. The sensor control device 15 defines the feature line in the groove as a reference angle for the groove information (for example, a feature point), and gives a target relative angle to the reference angle in combination with the traveling direction vector. , Generate a target orientation of the welding torch 13 with respect to the groove. Here, in the groove information based on the distance measurement data obtained from the laser sensor LS, the position / orientation of the feature point with respect to the groove coordinate system is calculated. Therefore, the robot control device 20 transmits the current coordinates of the welding torch 13 in the robot coordinate system to the sensor control device 15.

The sensor control device 15 uses the current coordinates of the robot coordinate system of the received welding torch 13, the feature point coordinates acquired by image analysis, and the speed (speed data) given in advance to determine the target position (that is, the target position) in the robot coordinate system. , Target coordinates) and send it to the robot control device 20.

Here, the laser sensor LS and the sensor control device 15 may be replaced with an image pickup device such as a camera and an image pickup control device, respectively. In the technique of the present disclosure, since it is sufficient that the groove information of the welding destination can be acquired in the welding target section, the sensor is obtained by imaging the groove portion in the imaging device and performing image analysis in the imaging control device. Similar to the control device 15, the imaging control device can acquire the groove information. The acquired groove information is transmitted to the robot control device 20.

(Robot control device 20)
The robot control device 20 operates the robot 10 by replacing the interpolation points generated from the teaching data used for welding with the received target positions (target coordinates). Here, in the adaptive welding function using the laser sensor LS, the robot control device 20 refers to the preset adaptive welding condition table, and the welding parameters included in the welding conditions commanded to the welding power source 401 according to the groove information. (For example, welding current and welding voltage) can be changed in real time. For example, an adaptive welding condition table that changes the welding current, which is one of the welding conditions, is set according to the gap amount G as the groove information. In this example, the welding current Is changes stepwise or linearly according to the gap amount G.

The robot control device 20 controls the robot 10 and the welding machine 40 according to the instructions from the control unit 21 having the adaptive welding function described above. The robot control device 20 further determines the threshold value of the welding abnormality by using the measured values of the welding parameters. The robot control device 20 includes a control unit 21, a storage unit 22, and a servo control unit 23 in order to perform the adaptive welding process and the abnormality determination process described above.

The storage unit 22 includes a welding condition storage unit 22A, a program storage unit 22B, and a sampling buffer 22C, and can store various programs and various data files.

The welding condition storage unit 22A stores, for example, the set values (command values) of the welding current Is, the welding voltage Vs, the wire feeding speed Vf, and the welding speed Vw, the threshold value used for determining the threshold value of the welding abnormality, and the like. Further, the welding condition storage unit 22A includes the respective values of the parameters (gap, step, etc.) related to the abnormality of the work shape as described above, and the correction values of the welding parameters (welding current or welding voltage) corresponding to these values. The adaptive welding condition table associated with the above may be stored.

The program storage unit 22B stores a control program for controlling the operation of the articulated arm, a determination program used for threshold value determination, and the like. The control program and the determination program are stored in, for example, a ROM (read only memory). Further, the program storage unit 22B stores one or a plurality of work programs in which the procedure of the welding work of the robot 10 is taught. One or more work programs are stored, for example, on a hard disk.

The sampling buffer 22C stores various data generated by executing the determination program. These various types of data are stored in, for example, a RAM (Random Access Memory).

Various data include, for example, measurement of welding parameters such as a measurement value of welding current Is at the time of welding, a measurement value of welding voltage Vs obtained from the welding machine 40, a measurement value of wire feeding speed Vf, and a measurement value of welding speed Vw. The value.

The servo control unit 23 controls each robot motor 101 of the robot 10. The servo control unit 23 controls each robot motor 101 of the robot 10 based on the movement command described in the work program and the position information from the encoder of the robot 10. The movement command may include, for example, a movement start command, a movement stop command, a work path (teaching data), and a torch posture based on a target position in the robot coordinate system received from the sensor control device 15. Further, the servo control unit 23 derives (measures) the welding speed Vw based on the position information from the encoder of the robot 10. The servo control unit 23 outputs the welding speed Vw to the control unit 21.

The control unit 21 has an analysis unit 211 that reads out a work program and an arc welding abnormality determination program based on a work command input from the input / output terminal 30 and analyzes the contents thereof. The analysis unit 211 generates instruction notifications corresponding to the instructions described in these programs based on the analysis results.

The control unit 21 has an execution unit 212 that outputs a movement command or a welding command according to the content of the command notification generated by the analysis unit 211. The execution unit 212 generates, for example, a notification (monitoring start notification) for starting monitoring based on the abnormality determination program in response to the monitor information (for example, arc generation notification) input from the welding machine 40. Further, the execution unit 212 may generate, for example, a notification (monitoring end notification) for ending monitoring based on the determination program according to the welding distance, or welding ends using the ranging data from the laser sensor LS. The position may be specified to generate a monitoring end notification. The welding distance is derived by, for example, the welding speed Vw × the arc time At. The execution unit 212 derives the welding distance using the welding speed Vw input from the servo control unit 23 and the time (arc time) after receiving the arc generation notification.

The control unit 21 has a welding control unit 213 that outputs a voltage command value and a current command value to the welding machine 40 based on the welding command generated by the execution unit 212. For example, the welding control unit 213 notifies the welding power supply 401 of the welding machine 40 of the voltage command value and the current command value together with the welding command. Although the welding control unit 213 will be described with reference to FIG. 2, as described above, the welding control unit 213 has an adaptive welding function and adaptively responds to the groove information of the welding target with command values of welding parameters (for example, voltage command values and currents). (Command value) is corrected. The correction value used for correcting the command value of the welding parameter is notified to the processing unit 214.

The control unit 21 has a processing unit 214 that executes an arc welding abnormality determination program in accordance with a monitoring start notification from the execution unit 212. As will be described later with reference to FIG. 2, the processing unit 214 determines the welding abnormality by using the measured value of the welding parameter stored in the sampling buffer 22C and the threshold value. Regarding the threshold value, the processing unit 214 appropriately adjusts the threshold value used for the abnormality determination according to the value of the welding parameter corrected according to the groove information. Therefore, by using this adjusted threshold value, the threshold value is determined in consideration of the correction of the command value of the welding parameter. The processing unit 214 may acquire the threshold value and the like used for the abnormality determination from the welding condition storage unit 22A.

By communicating with the welding machine 40, the control unit 21 synchronizes with the welding machine 40 and instructs, for example, the start and end of arc welding, the setting of the welding voltage Vs, or the setting of the wire feeding speed Vf. .. Further, the control unit 21 instructs the welding machine 40 to control the wire feeding device, and the welding machine 40 sends the welding wire 14 to the wire feeding device, for example, the start or end of arc welding, or the welding voltage. Instructs the setting of Vs and the like.

(I / O terminal 30)
The input / output terminal 30 is a device in which an operator teaches the operation of the robot 10. The input / output terminal 30 is, for example, a computer or the like, and has a control unit, a display unit, an input unit, a communication unit, and a storage unit included in a general computer.

The display unit of the input / output terminal 30 displays a video when a video signal is input. For example, a graph showing an abnormality determination result of arc welding is displayed. The input unit of the input / output terminal 30 receives the instruction from the operator, generates an input signal according to the operation of the operator, and outputs the input signal to the control unit. The communication unit of the input / output terminal 30 communicates with the robot control device 20 via a cable, and transmits a work command from the control unit to the robot control device 20. Further, this communication unit receives the monitoring information from the robot control device 20 and outputs it to the control unit. The storage unit of the input / output terminal 30 stores a teaching program that enables various displays and work instructions in various modes. The teaching program is stored in, for example, a ROM.

The control unit of the input / output terminal 30 generates a video signal and outputs it to the display unit, and also generates a work command as necessary and outputs it to the communication unit. The control unit generates a video signal according to the read teaching program, and generates a work command as needed. For example, when the control unit acquires the monitoring information from the communication unit, the control unit generates a video signal for displaying the acquired monitoring information.

(Welding machine 40)
The welding machine 40 generates an arc between the tip of the welding wire 14 and the work W by controlling the welding current Is, the welding voltage Vs, the wire feeding speed Vf, and the like based on the control by the robot control device 20. Let me. The welding machine 40 has a welding power supply 401, a welding monitoring unit 402, and the like.

The welding machine 40 controls the operation of the wire feeding device based on the welding command from the robot control device 20. The welding command from the robot control device 20 may include, for example, a voltage command, a current command, a wire feeding start command, a wire feeding stop command, a set value of the wire feeding speed Vf, and the like.

The welding power supply 401 has, for example, a digital inverter circuit, and performs precise welding current waveform control with a high-speed response by using an inverter control circuit for a commercial power supply (for example, three-phase 200V) input from the outside. That is, the welding power supply 401 supplies a high voltage welding voltage Vs between the welding torch 13 and the work W. The welding power supply 401 controls the welding current Is and the welding voltage Vs according to the voltage command value and the current command value from the robot control device 20. The welding command from the robot control device 20 includes, for example, an arc welding start command, an arc welding end command, a set value of welding current Is included in the current command, a set value of welding voltage Vs included in the voltage command, and the like. Can be included.

The welding monitoring unit 402 measures the welding current Is flowing between the welding torch 13 and the work W and the welding voltage Vs between the welding torch 13 and the work W. The welding monitoring unit 402 outputs the measured values of the welding current Is and the welding voltage Vs to the sampling buffer 22C of the robot control device 20. Further, the welding monitoring unit 402 measures the wire feeding speed Vf based on the pulse output from the motor of the wire feeding device (or some signal in place of the above pulse), and measures the wire feeding speed Vf. The value is output to the sampling buffer 22C of the robot control device 20.

(Arc welding abnormality judgment processing)
FIG. 2 is a block diagram showing an example of the functions of the welding control unit 213 and the processing unit 214 used for the arc welding abnormality determination process according to the embodiment. In the example shown in FIG. 2, the welding control unit 213 includes a command value control unit 302, a shape determination unit 304, and a correction unit 306, and the processing unit 214 includes a preliminary determination unit 352, an adjustment unit 354, and an abnormality determination unit 356. And the output unit 358 are included.

The command value control unit 302 controls the command value of the welding parameter output to the welding machine 40 based on the welding command generated by the execution unit 212 with respect to the welding target section. The command value of the welding parameter is, for example, a voltage command value, a current command value, or the like. Further, the command value control unit 302 corrects the command value of the welding parameter by using the correction value determined by the correction unit 306 described later. For example, the command value control unit 302 calculates the corrected command value by adding the correction value to the original command value. In this case, the corrected command value is output to the welding machine 40.

The shape determination unit 304 determines an abnormality in the work shape by using the groove measurement data acquired from the laser sensor LS or the groove information of the welding target based on the image information acquired from the image pickup apparatus. Regarding the abnormality of the work shape, if there is a gap or step above a predetermined value in the welded joint, it is judged to be abnormal. As a result, it is possible to execute the correction process for the command value only when it is determined to be abnormal.

When an abnormality in the work shape is determined, the correction unit 306 determines a correction value for the command value of the welding parameter according to the degree of the abnormality. For example, the correction unit 306 can determine the correction value by acquiring the correction value corresponding to the value of the groove information such as a gap or a step by using a function or the like that calculates the correction value from the groove information. It is possible.

The correction unit 306 refers to the adaptive welding condition table according to the value of the groove information without determining an abnormality in the work shape, and sets a correction value corresponding to the value of the groove information such as a gap or a step. You may decide. As a result, the welding process can be performed quickly by omitting the abnormality determination process of the work shape.

The pre-determination unit 352 may determine whether or not a threshold value used for welding abnormality determination is set for the welding target section. For example, the pre-determination unit 352 determines whether or not it is a determination section in which a threshold value for determining a welding abnormality is set by acquiring specific information of the welding target section or the like before the welding operation. The pre-determination unit 352 outputs the determination result to the shape determination unit 304 or the adjustment unit 354.

For example, when the shape determination unit 304 determines an abnormality in the work shape, if the advance determination unit 352 determines that the welding target section is a section in which a threshold value is set, the shape determination unit 304 uses the work. Start the process of determining the shape abnormality. Further, when the correction value is determined using the groove information without performing the abnormality determination of the work shape, it is determined by the pre-determination unit 352 that the welding target section is a section in which the threshold value is set. , The adjustment unit 354 starts the threshold adjustment process.

As a result, the welding target section includes a section in which the threshold value is set in advance and a section in which the threshold value is not set, but the threshold value is adaptively changed for the section in which the threshold value is set in advance. At the same time, since welding abnormality is determined, it is possible to improve the accuracy of welding abnormality determination.

The adjusting unit 354 adjusts the threshold value used for determining the welding abnormality based on the correction value determined by the correction unit 306. For example, the adjusting unit 354 adjusts the threshold value used at that time by using the correction value of the command value of the welding parameter which is adaptively corrected while welding. More specifically, when the welding current is used as the welding parameter, the adjusting unit 354 increases the correction value for increasing the command value of the welding current as the gap in the welding section increases, and sets this correction value as a threshold value. The correction value is adjusted by adding to each time.

The abnormality determination unit 356 determines an abnormality in arc welding by using the threshold value adjusted by the adjustment unit 354 and the measured value of the welding parameter measured corresponding to the adjustment of the threshold value. For example, if there is an upper limit threshold value and a lower limit threshold value as the threshold value, the abnormality determination unit 356 determines whether or not the measured value of the measured welding parameter is included between the upper limit threshold value and the lower limit threshold value. If the determination result is affirmative (if the measured value is included between the upper limit threshold value and the lower limit threshold value), the abnormality determination unit 356 determines that there is no welding abnormality, and if the determination result is negative (the measured value is the upper limit). If it deviates between the threshold value and the lower limit threshold value), it is determined that there is a welding abnormality.

The output unit 358 outputs the result of the abnormality determination by the abnormality determination unit 356 to, for example, the input / output terminal 30. Further, the output unit 358 may transmit the result information indicating the result of the abnormality determination to a preset destination.

As a result, the threshold value used for determining welding abnormalities is also adaptively adjusted in response to the correction value adaptively adjusted to the command value of the welding parameter, so that it is suitable for the command value of the welded parameter after adjustment. It is possible to determine the welding abnormality by using the threshold value, and it is possible to improve the accuracy of determining the welding abnormality.

Further, the correction unit 306 may determine the correction value based on the correction information in which each value of the parameter related to the abnormality of the work shape and each correction value corresponding to each value are associated with each other. For example, an adaptive welding condition table (correction information) is used in which the parameters related to the abnormality of the work shape include any parameter such as a gap or a step, and the correction value is associated with the value of each parameter. The correction unit 306 specifies the value of this parameter (for example, the value of a gap or a step) based on the groove information, and determines the correction value corresponding to the value of this parameter with reference to the adaptive welding condition table.

As a result, a correction value is set in advance for an abnormality in the work shape that may occur in the section to be welded, and an appropriate correction value is used according to the abnormality in the work shape to determine the command value of the welding parameter. Therefore, it is possible to improve the accuracy of welding abnormality determination because the welding abnormality is determined while improving the welding accuracy and the threshold value is adaptively changed.

Although the welding current has been described as an example of the welding parameters, other parameters such as the welding voltage and the feed load (= motor rated current / motor current × 100) may be used. Further, the welding parameter that outputs the command value in the welding control unit 213 and the welding parameter used for determining the welding abnormality may be different. For example, the welding control unit 213 outputs a command value of the welding current, but the welding parameter used in the abnormality determination unit 356 may be a feed load.

<Specific example>
Hereinafter, the disclosed welding abnormality determination process will be described with reference to FIGS. 3 to 9. In the example shown below, it is assumed that the object controlled by the welding control unit 213 and the object determined by the abnormality determination unit 356 are the welding current.

FIG. 3 is a diagram illustrating normality or abnormality of the work shape according to the embodiment. FIG. 3A shows that there are no gaps or steps in the joints between the base materials 400, and the work shape is normal. On the other hand, FIG. 3B shows that there is a gap in the joint between the base materials 400 and the work shape is abnormal. An example in which the gap G gradually increases is shown, but the gap G is not limited to this example.

FIG. 4 is a diagram showing an example of the relationship between the welding current and the threshold value in the predetermined welding section according to the embodiment. In the example shown in FIG. 4, the welding current Is indicates the transition (current waveform) of the welding current from the start of welding to the end of welding in a predetermined welding section. Further, the welding current Is may indicate the average value of the welding currents measured a plurality of times when the work shape is normal. The threshold Th1 indicates the transition of the upper limit threshold value (threshold value waveform) with respect to the transition of the welding current, and the threshold value Th2 indicates the transition of the lower limit threshold value with respect to the transition of the welding current.

FIG. 5 is a diagram showing an example of a predetermined welding section according to the embodiment. The example shown in FIG. 5 is an example in which the weld beads 410 are formed as the work W so that the two base materials 400 are parallel to each other and the ends of the two base materials 400 are in contact with each other. is there. The welding monitoring unit 402 measures the welding parameters from the start of welding to the end of welding in the welding section as shown in FIG.

FIG. 6 is a diagram showing an example of a command value after correction for a welding current when the work shape according to the embodiment is abnormal. FIG. 7 is a diagram showing the relationship between the gap G showing the gap according to the embodiment and the welding time. FIG. 8 is a diagram showing an example of an adaptive welding condition table showing the relationship between the gap and the change amount (correction value) according to the embodiment. In FIGS. 6 to 8, for example, it is assumed that the work shape has a shape abnormality in which the gap G gradually increases as shown in FIG. 3 (B). The welding time shown in FIG. 7 may be the distance from the start of welding.

In this case, as shown in FIG. 7, a gap is specified from the groove information at a certain time, and the correction unit 306 refers to the welding condition table shown in FIG. 8 based on the specified gap to correct the value. To determine. For example, if the gap is 5 mm, the correction value for the command value of the welding current is 3 A.

Next, the command value control unit 302 corrects the command value of the welding current included in the welding command by using the determined correction value. For example, the command value control unit 302 adds a correction value to the originally set command value if it is positive, and if it is negative, the correction value is corrected from the originally set command value. Is subtracted. The command value of the welding current from the start of welding to the end of welding corrected in this way represents the current waveform Is2 shown in FIG.

FIG. 9 is a diagram showing an example of adjusting the threshold value according to the embodiment. In the example shown in FIG. 9, the welding current Is, the upper limit threshold value Th1 and the lower limit threshold value Th2 are the same as those shown in FIG. 3, and therefore have the same reference numerals. That is, the measured value of the welding current when the work shape is normal, and the upper limit threshold value and the lower limit threshold value for the measured value are shown.

The upper limit threshold Th3 is calculated by adding a correction value from the upper limit threshold Th1 each time, and the lower limit threshold Th4 is calculated by adding a correction value from the lower limit threshold Th2. If the correction value in the adaptive welding condition table shown in FIG. 8 shows a negative value, the correction value is subtracted from the original upper limit threshold value and lower limit threshold value.

In the specific example described above, the abnormality determination unit 356 uses the adjusted upper limit threshold value Th3 and lower limit threshold value Th4 at the same time shown in FIG. 9 for the measured value of the corrected welding current shown in FIG. Make an abnormality judgment. As a result, by adaptively adjusting the threshold value according to the command value to be adaptively corrected, it becomes possible to appropriately determine the abnormality of the measured value with respect to the corrected command value.

<Operation>
FIG. 10 is a flowchart showing an example of the abnormality determination procedure according to the embodiment. In the example shown in FIG. 10, a welding current is used as an example of welding parameters, and a gap is used as a parameter for determining an abnormality in the work shape.

In step S102, the pre-determination unit 352 determines whether or not the target section to be welded from now on is a section (determination section) for which the threshold value is determined. For example, the pre-determination unit 352 determines whether or not it is a determination section in which a threshold value for determining a welding abnormality is set by acquiring specific information of the target section or the like before the welding operation. If the target section is a determination section (step S102-YES), the process proceeds to step S104, and if the target section is not a determination section (step S102-NO), the process ends.

In step S104, the correction unit 306 determines the correction value (current value) of the welding current according to the gap of the welded portion (welding target section) (see, for example, FIG. 8).

In step S106, the adjusting unit 354 adjusts the threshold value based on the determined correction value. As described above, for example, the correction value is added or subtracted from the upper limit threshold value and the lower limit threshold value.

In step S122, the abnormality determination unit 356 determines the threshold value of the welding abnormality. The output unit 310 outputs the determination result to a preset destination. The other party is, for example, an input / output terminal 30 or a terminal of a predetermined worker.

According to the above-mentioned abnormality determination procedure, the threshold value used for welding abnormality determination is also adaptively adjusted in response to the correction value adaptively adjusted with respect to the command value of the welding parameter. Welding abnormality can be determined by using a threshold value suitable for the command value, and the welding abnormality determination accuracy can be improved.

Further, each process shown in FIG. 9 may be implemented as a determination program executed by a computer. This determination program is installed in the robot control device 20, stored in a storage medium readable by a computer (for example, a non-temporary storage medium), and executed by a control unit (for example, a processor) of the computer. Then, the above processing may be realized.

Further, each function in the control unit 21 of the robot control device 20 may be configured to function in the control unit of the input / output terminal 30. In this case, the sampling buffer 22C may be included in either the robot control device 20 or the input / output terminal 30.

The embodiments described above are for facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those exemplified, and can be changed as appropriate. For example, the above-mentioned processing steps can be arbitrarily changed in order or executed in parallel as long as the processing contents do not conflict with each other.

1 ... Robot control system, 10 ... Robot, 11 ... Worktable, 13 ... Welding torch, 14 ... Welding wire, 15 ... Sensor control device, 20 ... Robot control device, 21, Control unit, 22 ... Storage unit, 30 ... Output terminal, 40 ... Welding machine, 101 ... Robot motor, 211 ... Analysis unit, 212 ... Execution unit, 213 ... Welding control unit, 214 ... Processing unit, 302 ... Command value control unit, 304 ... Shape determination unit, 306 ... Correction Unit, 352 ... Preliminary determination unit, 354 ... Adjustment unit, 356 ... Abnormality determination unit, 358 ... Output unit, 401 ... Welding power supply, 402 ... Welding monitoring unit.

Claims (5)

A correction unit that determines the correction value for the command value of the welding parameter using the distance measurement data acquired from the laser sensor or the groove information of the welding target based on the image information acquired from the image pickup device.
An adjustment unit that adjusts the threshold value used for determining welding abnormalities based on the correction value, and
An abnormality determination unit that determines welding abnormalities using the adjusted threshold value and the measured values of welding parameters, and
A control device including an output unit that outputs the result of the abnormality determination. A pre-determination unit for determining whether or not a threshold value used for welding abnormality determination is set for the welding target section is further provided.
The control device according to claim 1, wherein when it is determined that the interval is a section in which the threshold value is set, the adjustment unit performs the threshold value adjustment process. The correction unit
The control according to claim 1 or 2, wherein the correction value is determined based on the correction information associated with each value of the parameter related to the abnormality of the work shape and each correction value corresponding to each value. apparatus. On the computer
The step of determining the correction value for the command value of the welding parameter by using the groove information of the welding target based on the ranging data acquired from the laser sensor or the image information acquired from the imaging device, and
Based on the correction value, the step of adjusting the threshold value used for determining the welding abnormality and
A step of determining a welding abnormality using the adjusted threshold value and the measured value of the welding parameter, and
A program that executes a step that outputs the result of the abnormality determination. A robot control system including a robot and a control device that controls the robot to perform welding.
The control device is
A correction unit that determines the correction value for the command value of the welding parameter using the distance measurement data acquired from the laser sensor or the groove information of the welding target based on the image information acquired from the image pickup device.
An adjustment unit that adjusts the threshold value used for determining welding abnormalities based on the correction value, and
An abnormality determination unit that determines welding abnormalities using the adjusted threshold value and the measured values of welding parameters, and
A robot control system including an output unit that outputs the result of the abnormality determination.