JPH08103869A - Welding robot - Google Patents

Abstract

PURPOSE: To prevent the defective welding by scanning the part to be welded, calculating the deviation from the reference position, and correcting the teaching data to achieve the welding, or displaying the error to stop the operation of a robot when the deviation meets the predetermined error condition. CONSTITUTION: A sensor 21 is scanned in the teaching mode to prepare the teaching data, and the data are stored in a storage part 13b. The part to be welded of a work is scanned in the feedback mode, comparison is made with the teaching data, and a deviation calculating part 13c calculates the deviation. A correcting part 13d corrects the teaching data according to the deviation, and outputs the corrected data to a robot controller 12 to achieve the welding. When an error judging part 13e makes a judgement that the deviation meets the predetermined error condition, the error number is displayed and a robot body 11 is stopped. Thus, no welding is achieved based on the mistaken data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a sensor with a welding torch on the distal wrist of a moving arm, and the sensor senses the shape (including the position) of the planned welding site and uses the sensing data in advance. The present invention relates to a teaching playback type arc welding robot (hereinafter, simply referred to as a welding robot) that performs welding while correcting taught data.

[0002]

2. Description of the Related Art Conventionally, as a welding robot of this type,
For example, JP-A-5-212540 and Japanese Patent Application No. 6-1
There is one described in Japanese Patent No. 6293. In such a welding robot 1, as shown in FIG. 5, a laser sensor 4 and a welding torch 5 are arranged on the tip wrist of the movable arm 3 arranged on the pedestal 2. The laser sensor 4
Is arranged so that it can be scanned with a laser beam along a detection line in a direction orthogonal to the direction of the planned welding line in the vicinity of the welded portion, and a part of the laser diffused light diffusely reflected on the surface of the workpiece during scanning is The light is received and the shape such as the position of the planned welding site is detected.

In this welding robot 1, as shown in the figure, first, the teaching (teaching) mode is set, the movable arm 3 is directed toward a teaching object 7'of the same size and size as the object 7 to be welded, and the robot body ( The controller 6 for controlling the manipulator) learns and stores in advance a welding reference position for welding and a sensor measurement position for performing measurement by scanning with the laser sensor 4. After that, the movable arm 3 is directed to the workpiece 7 on the feed line L in the playback mode, and the planned welding position of the workpiece 7 is stored based on the stored welding reference position and sensor measurement position. Deviation is detected to create position correction data, and based on this position correction data, the controller 6 corrects the position difference between the stored welding reference position and the detected planned welding position, and the workpiece is welded. The welding torch 5 welds to the welding scheduled portion 8 of 7. According to the welding robot having such a configuration, it is possible to perform the welding faithful to the teaching content at the accurate welding scheduled position for the object to be welded which is difficult to be repeatedly positioned at the accurate position.

[0004]

By the way, when the laser sensor senses the planned welding site of the object to be welded, erroneous data may be sent to the controller for some reason. In this case, if the teaching data is corrected based on the data from the laser sensor as it is and welding is performed, there is a possibility that welding failure may occur or the welding torch may hit the workpiece.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a welding robot capable of immediately coping with the occurrence of a sensing error on the controller side.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 has a robot main body provided with a welding torch at a tip of a moving arm and a sensor for measuring a surface position of a planned welding site. A robot control means for controlling the movement of the moving arm of the robot body and the welding operation; an analysis means for analyzing the reference position of the planned welding site from the data of the sensor; a storage means for storing teaching data; Deviation amount calculating means for calculating an amount of deviation between the reference position included in the teaching data and the reference position of the planned welding site of the workpiece to be analyzed by the analyzing means, and the teaching data based on the output of the deviation amount calculating means. In the welding robot in which the robot control means controls the robot body according to the output of the correction means, the sensor or the deviation amount calculation means is provided. Error determining means for determining whether or not the signal from the above corresponds to a predetermined error condition, and error signal generating means for sending an error signal to the robot control means when the error determining means determines an error. The feature is that it is provided.

According to a second aspect of the present invention, in the welding robot according to the first aspect, the error determining means determines which of a plurality of error conditions given in advance corresponds to which error condition. The error signal generating means sends to the robot control means an error signal corresponding to a corresponding error condition among different error signals corresponding to the respective error conditions.

The invention according to claim 3 is the welding robot according to claim 2, wherein the robot control means is:
It is characterized in that a screen corresponding to the input error signal is displayed on the display device.

Further, the invention according to claim 4 is the welding robot according to claim 2 or 3, wherein when the error determining means determines that a plurality of error conditions are satisfied, the error signal generating means preliminarily sets the error signal generating means in advance. It is characterized in that only an error signal corresponding to an error condition having a higher priority than the determined priority is sent to the robot control means.

Further, the invention according to claim 5 is the welding robot according to any one of claims 1 to 4,
It is characterized in that the reference position included in the teaching data is a position obtained by scanning the above-mentioned sensor on a planned welding site of the teaching object and analyzing it by the analyzing means.

[0011]

According to the first aspect of the invention, the reference position of the planned welding site of the workpiece is analyzed based on the data from the sensor, and the reference position of the teaching data taught in advance and the reference position detected by the sensor are deviated. The amount is calculated, the teaching data is corrected according to the amount of deviation, and the robot control means controls the robot main body based on the corrected teaching data to perform welding. At this time, if the data of the sensor or the data of the deviation amount calculation means matches a predetermined error condition (for example,
When the sensor data is not usable as it is or the amount of deviation is extremely large), that is, when a sensing error occurs, an error signal is sent from the error signal generating means to the robot control means.

According to the second aspect of the invention, since an error signal according to the content of the sensing error is sent to the robot control means, the robot control means can deal with each error.

According to the third aspect of the invention, when a sensing error occurs, a screen showing the content of the error is displayed on the display device.

Further, in the invention according to claim 4, when the error contents correspond to a plurality of error conditions, only the error contents having a higher priority are displayed on the display device.

According to the fifth aspect of the invention, the reference position of the teaching data is determined by scanning the sensor at the planned welding site of the teaching object. Then, the deviation between the teaching data and the actual reference position of the workpiece is calculated, and the teaching data is corrected based on the result to control the welding robot.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an entire welding robot system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an electrical configuration of a sensor controller applied to the system. The welding robot of this example is installed in an assembly plant of a steel frame type building unit, and performs arc welding of steel beams and columns of a structure temporarily assembled on a feed line via a joint piece. As shown in FIG. 1, the robot main body 11, the robot controller 12, the sensor controller 13, the display device (monitor) 14, and the teaching box 15 are provided.
A personal computer or host computer can be connected as needed.

The robot main body 11 has a multi-joint structure in which a motor and a speed reducer are directly attached to each joint.
A moving arm portion 16 that can be driven three-dimensionally and can take a desired posture is provided on the above. The moving arm portion 16 includes two arms (a first arm 17a and a second arm 17b), a movable arm 17 that can be driven in a predetermined direction, and a wrist portion 18 provided at the tip of the movable arm 17. The movable arm 17 includes a base portion 19 which rotatably supports the base end portion of the movable arm 17 on the pedestal 2 and drives the movable arm 17 to reciprocate between the object to be welded and the teaching object. The wrist 18 is provided with a welding torch 20 and a laser sensor 21 for detecting the shape of the planned welding site and the position of the planned welding line.

FIG. 3 is a partial perspective view showing an example of an object to be welded 50 which is a structure. In this example, the object to be welded 5
Reference numeral 0 is a part of the steel frame of the building unit, which is a column 51 made of a rectangular steel pipe with an R portion at each corner, and a joint piece 5 arranged close to the upper end or the lower end of the column 51.
2 and the edge portion 52a of the joint piece 52
However, they are temporarily attached in advance to the corners of the columns 51 with a gap of about several mm. And this joint piece 52
A welding planned line P for arc welding is set along the edge portion 52a so as to join the edge portion 52a and the corner portion of the column 51. The joint piece 52 connects the beam to the pillar 51.
Is a joining member having a U-shaped cross section for joining and erection on the joint piece 52, and when the joint piece 52 and the column 51 are arc-welded, the beam is already inserted into the U-shaped concave portion of the joint piece, The double structure portion is spot welded and fixed to each other. That is, after the steel skeleton of the building unit is temporarily assembled on the feed line, the corners of the steel skeleton (upper and lower ends of the pillar 51 and the joint piece 51) are assembled.
The joining part) is to be main welded by the welding robot of this example.

The laser sensor 21 includes a light emitting portion including a semiconductor laser and a light projecting lens, and a light receiving portion including an image forming lens, a position detecting element (PSD) and the like, and light emitted from the semiconductor laser is projected. When a beam spot is created on the DUT by the optical lens, the beam spot is diffusely reflected (diffuse reflected) on the DUT surface, and a part of it returns to the position on the position detection element by the imaging lens. The image of the spot light and the distance from the front surface of the laser sensor 21 to the surface of the object to be measured can be measured. The laser sensor 21 is provided so as to be capable of scanning in the direction of the detection line S near the planned welding line P.
The surface position of the workpiece 50 along the detection line S is detected. The scanning mechanism of the laser sensor 21 may be one that drives the laser sensor 21 itself.
Inside the laser sensor 21, a mirror or the like may be used to change the irradiation direction of the light from the light emitting unit.

A sensor controller 13 is connected to the laser sensor 21. As shown in FIG. 2, the sensor controller 13 includes a shape analysis unit 13a, a storage unit 13b, a displacement amount calculation unit 13c, a correction unit 13d, and
An electrical configuration including an error determination unit 13e, an error signal generation unit 13f, a control unit 13g, a sensing drive circuit, a teaching data creation unit, an optimum condition selection unit, and a transmission circuit (all not shown). Has been done.

In the sensor controller 13, the sensing drive circuit is a circuit for scanning the laser sensor 21 positioned at the sensing position as described above, and the shape analysis section 13a is sent from the laser sensor 21. Based on the detection signal and according to a predetermined algorithm, the gap of the welding site of the workpiece 50,
Shape data such as the dimensions of the step or the like and the position of the edge portion 52a (in this example, the position of the edge portion is the planned welding position) are calculated. In the teaching mode, the teaching data creation unit (not shown) scans the laser sensor 21 to create teaching data including shape data of the simulated welding portion, and the RAM.
It is stored in the storage unit 13b including an EEPROM or the like.

In addition to storing the teaching data, the storage section 13b scans the laser sensor 21 and stores the amount of received light measured at each measurement point. In addition, the shift amount calculation unit 13c
Is the reference position (the position of the edge portion 52a 'taught by the teaching object 50') included in the teaching data and the reference position (the position of the edge portion 52a) of the planned welding site of the workpiece 50 analyzed by the shape analysis unit 13a. The amount of deviation from is calculated. Correction unit 13
In step d, the teaching data is corrected based on the output of the deviation amount calculator 13c. The optimum condition selection unit (not shown) selects the optimum welding condition according to the corrected teaching data from the optimum welding condition database stored in advance by the robot controller 12. Further, the error determination unit 13e determines whether or not the signal from the laser sensor 21 or the deviation amount calculation unit 13c meets a predetermined error condition. The error signal generation unit 13f generates an error signal when the error determination unit 13e determines an error. Further, a transmission circuit (not shown) transmits to the robot controller 12 the coordinate values (corrected teaching data) of the planned welding site, the optimum welding condition signal, and the error signal. The control unit 13g is C
A central processing unit (PU) and an internal memory such as ROM and RAM are provided, and the processing program stored in the ROM is stored in the RA.
The sensor controller 13 is executed by using M.
Control each part of the configuration.

The error determining section 13e in this example can determine which of a plurality of error conditions given in advance corresponds to the error condition. Then, the error signal generator 13f generates an error number corresponding to the corresponding error condition (different for each error condition). In particular, when the error determination unit 13e determines that a plurality of error conditions are met, the error signal generation unit 13f generates only an error number corresponding to a higher priority error condition of a predetermined priority. The specific relationship between the error condition and the error number will be described in the description of the operation.

The sensor controller 13 is connected to the robot controller 12, and the robot controller 12 sends the corrected teaching data (corrected coordinate values of the planned welding site) sent from the sensor controller 13 and the optimum welding conditions. Robot body 1 based on signals etc.
1 is performed and welding is performed. When an error signal is sent, the error signal is displayed on the display device 14, and the operation of the robot main body 11 is stopped if necessary. The optimum welding condition database in the robot controller 12 stores information such as current, voltage, speed, torch angle, and aiming angle for determining welding conditions based on the knowledge and experience of skilled workers.

Next, the operation of this example will be described. In the assembly plant of the building unit, the welding robot uses this welding robot to weld the planned welding site (column 51) of the workpiece 50.
And the joint piece 52), first, the teaching object is arranged outside the feed line so that the relative position with respect to the robot body 11 has the same relationship as the object to be welded on the feed line. . The teaching material is the same as the work piece or a modeled one. Then, the robot main body 11 is directed to this teaching object to perform teaching. That is, first, the welding robot 10 is taught the reference coordinates of the teaching object by moving the tip of the movable arm 17. Then,
By manually moving the tip of the welding torch 20 along the simulated welding planned line of the teaching object, the coordinate value of the moving arm portion 16 is detected and the welding reference line is calculated.

Next, the sensing position (laser sensor 21
Measurement position) is determined, the laser sensor 21 is scanned at that position, and the shape of the simulated welding site is analyzed by the measurement data. The analysis data includes the coordinate value of the edge portion (welding reference position) of the teaching object and the coordinate value of the welding reference line. In the case of this example, the sensing positions are two points that are vertically spaced (three points or more may of course be used).

Next, the movable arm 17 of the robot body 11
Is returned to the object to be welded 50 on the feed line to enter the regeneration mode. At this time, the coordinate values in the work space are calculated using only the coordinate values of the movable arm 18 and the wrist 19 among the coordinate values when the teaching is performed toward the teaching object. The coordinate value of the base portion 20 used for the reciprocating motion between the object and the object to be welded 50 is excluded, and the welding planned portion of the object to be welded 50 on the feed line is scanned as it is. That is, as shown in FIG. 3, the laser sensor 21 is scanned at two upper and lower sensing positions SP1 and SP2 (h indicates a scanning range in the figure), and the edge portion (welding planned position) 52a of the workpiece 50 is welded. The positions S1 and S2 are analyzed. Then, as shown in FIG. 4, a shift amount δ between the position of the edge portion 52a ′ analyzed by the teaching object 50 ′ and the position of the edge portion 52a analyzed by the workpiece 50 is calculated, and the upper and lower sensing positions SP1 , The larger deviation amount δ in SP2 is selected, the content of the teaching data is corrected according to the deviation amount δ, and the corrected data is used as the official coordinate data of the planned welding site. Then, the welding conditions corresponding to this data are selected and transmitted to the robot controller 12.

At the time of this sensing operation, the sensor controller 13 has an error diagnosis function, and it is determined whether or not the following error condition (diagnosis condition) is met. (1) The position S1 of the edge portion at the sensing position SP1 cannot be measured. (2) The position S2 of the edge portion at the sensing position SP2 cannot be measured. (3) The difference (deviation amount δ) between the position of the edge portion of the teaching data and the position S1 of the edge portion of the workpiece is not less than the predetermined value L1. (4) The difference (deviation amount δ) between the position of the edge portion of the teaching data and the position S2 of the edge portion of the workpiece is not less than the predetermined value L1. (5) The difference between S1 and S2 exceeds the predetermined value L2.

When the above error conditions are met, the error number corresponding to the applicable error condition is transmitted to the robot controller 12. In this case, there is a one-to-one correspondence between error numbers and error conditions, and different error numbers are associated with each other as follows.

Error number ... Error content 31 ... (1) 32 ... (2) 33 (*) ... (3) 34 (*) ... (4) 35 (*) ... (5)

Therefore, when an error corresponding to the above condition (2) occurs, the error number "32" is transmitted to the robot controller 12. When a plurality of errors occur simultaneously, the error number is sent at the same time. However, if there is a priority, only the error number with the higher priority is transmitted. Here, the error with the number without * is higher than the error with the number with *. Therefore, even if the error marked with * is detected, if the error number “31” or “32” occurs, the number marked with * is not transmitted.

When the error number "32" is transmitted, the robot controller 12 causes the display device to display the error number and jumps to the command word of the error number (sentence number) "32" to issue this command. Run. That is, the operation of the robot body is stopped. On the other hand, when the error number is not transmitted, the welding torch 20 is moved and welding is performed according to the corrected teaching data and the selected welding condition.

As described above, when a sensing error occurs, an error signal is immediately sent to the robot controller 12, so that the robot controller 12 can immediately deal with it. Therefore, there is no need to worry about welding due to incorrect sensing data,
There is no risk of welding failure or hitting the welding torch 20 on the workpiece 50. Also, by looking at the display screen, it is possible to know what error has occurred. Therefore,
You can deal with the error immediately. In particular, since only errors with higher priority are displayed, it is possible to efficiently eliminate the errors by coping with the displayed contents.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific structure is not limited to this embodiment, and there are design changes and the like within the scope not departing from the gist of the present invention. Also included in the present invention. For example, the error condition is not limited to the above example, and various settings can be made. The error number can also be set to any sentence number. Further, the sensor controller does not matter whether it has a software configuration or a hardware configuration. Further, in the above-described embodiment, the case where the sensor controller and the robot controller are separate from each other has been described. However, for example, the robot controller may also have the function of the sensor controller.

[0035]

As described above, according to the first aspect of the invention, when a sensing error occurs, an error signal is sent to the robot control means, so the robot control means handles the error. be able to. Therefore, there is no risk of welding being performed due to incorrect data, and there is no fear of causing welding defects or hitting the welding torch on the workpiece.

Further, according to the second aspect of the present invention, since the signal corresponding to the corresponding error condition is sent to the robot control means, the robot control means performs a coping method according to the content of the error. be able to.

According to the third aspect of the invention, it is possible to know what error has occurred by looking at the display screen.
Therefore, the error can be dealt with immediately.

Further, according to the invention of claim 4, since only the errors of higher priority are displayed, it is possible to efficiently eliminate the errors by coping with the displayed contents.

Further, according to the invention of claim 5, the teaching data is corrected according to the deviation between the teaching data (reference position) taught by the teaching object and the sensing data (scheduled welding position). Even if the position of the object is slightly deviated from the taught position, it is possible to perform welding at an accurate planned welding position.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an entire system of a welding robot according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of a sensor controller applied to the system.

FIG. 3 is a diagram for explaining how a laser sensor mounted on the welding robot senses a planned welding site of an object to be welded.

FIG. 4 is a plan view for explaining the positional deviation of the edge portion between the teaching object and the object to be welded according to the same embodiment.

FIG. 5 is a plan view showing a schematic configuration of a conventional welding robot.

[Explanation of symbols]

 10 welding robot 11 robot body 12 robot controller (robot control means) 13 sensor controller 13a shape analysis unit 13b storage unit 13c deviation amount calculation unit 13d correction unit 13e error determination unit 13f error signal generation unit 13g control unit 16 moving arm unit 20 welding Torch 21 Laser sensor 50 Workpiece 52a Edge part (reference position) δ Deviation amount

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Claims (5)

[Claims] 1. A robot main body having a welding torch at a tip of a moving arm portion and a sensor for measuring a surface position of a planned welding site, and a robot control means for controlling the movement and welding operation of the moving arm portion of the robot main body. And analysis means for analyzing the reference position of the planned welding site from the data of the sensor, storage means for storing teaching data, welding schedule of the workpiece to be analyzed analyzed by the reference position and the teaching data included in the teaching data. Deviation amount calculating means for calculating the amount of deviation of the part from the reference position,
A welding robot in which a correction means for correcting the teaching data based on the output of the deviation amount calculation means is provided, and the robot control means controls the robot main body in accordance with the output of the correction means. Error determination means for determining whether or not the signal from the amount calculation means meets a predetermined error condition, and an error signal generation for sending an error signal to the robot control means when the error determination means determines an error A welding robot characterized in that it is provided with means. 2. The welding robot according to claim 1, wherein the error determination means determines which one of a plurality of error conditions given in advance corresponds to, and the error signal generation means Among the different error signals corresponding to each of the error conditions, an error signal corresponding to the corresponding error condition is sent to the robot control means. 3. The welding robot according to claim 2, wherein the robot control means causes a display device to display a screen corresponding to the input error signal. 4. The welding robot according to claim 2, wherein, when the error determining means determines that a plurality of error conditions are satisfied, the error signal generating means has a higher priority error condition of a predetermined priority. A welding robot characterized in that only an error signal corresponding to is sent to the robot control means. 5. The welding robot according to claim 1, wherein the reference position included in the teaching data causes the sensor to scan a welding planned portion of the teaching object and analyzes the reference position. A welding robot characterized by the obtained position.