JP2023108410A - Robot control device - Google Patents

Abstract

To provide a robot control device that allows reduction in tact time while keeping cost low.SOLUTION: A robot control device includes: a point cloud data detection unit for detecting coordinate data corresponding to a workpiece W on which a manipulator 2 works as workpiece point cloud data from three-dimensional image data containing the workpiece W; an error calculation unit for calculating an error by comparing the detected workpiece point cloud data with a prestored reference point cloud data serving as a reference; and a sensor control unit for starting sensing by a laser sensor 3 from a sensing start position corresponding to the calculated error in a direction of approaching the workpiece W.SELECTED DRAWING: Figure 1

Description

The present invention relates to a robot controller.

2. Description of the Related Art When an industrial robot performs work, the position of an object is measured and corrected to the correct position in order to prevent misalignment of the target caused by an installation error of the object or a machining error of the robot. Methods for measuring the position of an object include, for example, a method using a 2D camera and a laser sensor and a method using a 3D camera. Patent Document 1 below discloses a method for measuring the position and orientation of an object using a two-dimensional CCD camera and a laser sensor. Patent Document 2 below discloses three-dimensional data measured by a three-dimensional measuring instrument. Disclosed is a method for determining the position of an object using

Japanese Patent No. 3556589 JP 2009-222568 A

By the way, the method using a 2D camera and a laser sensor has the problem that the 2D camera cannot accurately measure the distance to the object, and the laser sensor has a narrow range in which the object can be detected. The method using a 3D camera has a problem that a 3D camera with high detection accuracy is expensive and the cost increases. In order to avoid these problems, when using a 2D camera and laser sensor, it is possible to grope for sensing from a distant position so that the laser sensor does not interfere with the target object, but this increases the takt time. put away. Also, when using a 3D camera, an inexpensive three-dimensional camera can be used in order to keep costs down.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a robot controller capable of reducing the tact time while suppressing the cost.

A robot control device according to an aspect of the present invention detects, as target object point cloud data, three-dimensional coordinate data corresponding to an object from three-dimensional image data including an object to be worked by an industrial robot. A data detection unit, an error calculation unit that compares the detected object point cloud data with reference point cloud data that is stored in advance to calculate an error, and a sensing start position corresponding to the calculated error. a sensor control unit that causes the sensor to start sensing in a direction approaching the object.

According to this aspect, the three-dimensional object point cloud data corresponding to the object detected from the three-dimensional image data including the object and the reference point cloud data are compared to determine the deviation from the reference position. A representative error can be calculated and the sensor can start sensing from a sensing start position corresponding to the error. As a result, even if the object is deviated from the reference position by the amount of the error, the sensing start position of the sensor can also be shifted according to the error, so that the efficiency of the sensing work can be improved. In addition, it is not necessary to use an expensive 3D camera because it is sufficient to capture three-dimensional image data.

In the above aspect, the error calculator may calculate the error based on the distance between the object point cloud data and the reference point cloud data.

According to this aspect, it is possible to control the starting position of the sensor using the distance by which the object point cloud data is separated from the reference point cloud data as an error.

In the above aspect, the error calculation unit calculates the distance between each point included in the object point cloud data and the approximate plane corresponding to the reference point cloud data, and uses the average value of the calculated distances as the error. can be calculated.

According to this aspect, it is possible to reduce the amount of calculation when calculating the error.

In the above aspect, the error calculation unit may calculate the distance between points having a corresponding positional relationship in the object point cloud data and the reference point cloud data, and calculate the average value of the calculated distances as the error. good.

According to this aspect, it is possible to improve the calculation accuracy of the error.

In the above aspect, the sensing start position is based on the fact that the industrial robot including the sensor does not interfere with the object even if the sensor moves a distance corresponding to the error from the sensing start position toward the object. may be set as

According to this aspect, even if the object deviates from the reference position by the amount of the error, the sensing start position can be shifted according to the error. It is possible to move without interfering with objects.

ADVANTAGE OF THE INVENTION According to this invention, the robot control apparatus which can shorten a tact time while holding down cost can be provided.

It is a figure which illustrates the structure of the robot system containing the robot control apparatus which concerns on embodiment. It is a figure which illustrates the functional structure of a robot control apparatus. FIG. 4 is a schematic diagram for explaining a visual field range of a laser sensor; FIG. 5 is a diagram for explaining an example of a correspondence relationship between an error and a sensing start position; FIG. 5 is a schematic diagram for explaining a sensing start position set based on an error; FIG. 5 is a schematic diagram for explaining a sensing start position set based on an error; FIG. 5 is a schematic diagram for explaining a sensing start position set based on an error;

Preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that, in each figure, the same reference numerals have the same or similar configurations. Also, since the drawings are schematic, the dimensions and proportions of each component are different from the actual ones.

FIG. 1 is a diagram illustrating the configuration of a robot system 100 including a robot control device 1 according to an embodiment. The robot system 100 includes, for example, a robot control device 1, a manipulator 2, a laser sensor 3, and an imaging terminal 4. Each device can be connected, for example, via a wired or wireless network such as a communication cable. Note that the robot system 100 may include a teaching pendant. A teaching pendant is an operation terminal for an operator to teach the operation of the manipulator 2 .

The manipulator 2 is a welding robot that performs arc welding according to construction conditions set by the robot controller 1 . The manipulator 2 has, for example, an articulated arm 21 provided on a base member fixed to the floor of a factory or the like, and a welding torch 22 connected to the tip of the articulated arm 21 .

The robot control device 1 is a control unit that controls the operation of the manipulator 2, and includes, for example, a control section 11, a storage section 12, a communication section 13, and a welding power source section .

The control unit 11 controls the manipulator 2 and the welding power source unit 14 by causing the processor to execute a work program stored in the storage unit 12, for example. The communication unit 13 controls communication with each device connected via the network.

The welding power supply unit 14, for example, in order to generate an arc between the tip of the welding wire and the work (object) W, according to predetermined welding execution conditions, the welding current and welding voltage, etc. to the manipulator 2. supply. The welding execution conditions include, for example, data items such as welding conditions, welding start position, welding end position, welding distance, welding torch posture, and the like. Welding conditions include data items such as welding current, welding voltage, welding speed, wire feed speed, and work thickness. The welding power source section 14 may be provided separately from the robot control device 1 .

The laser sensor 3 is attached to the tip of the articulated arm 21 of the manipulator 2 and measures the distance to the workpiece W. As shown in FIG. The laser sensor 3 is, for example, a scanning laser sensor, and includes a light-emitting portion that emits laser light toward the work W and a light-receiving portion that receives the laser beam reflected by the work W. A laser beam emitted by the light-emitting portion is diffusely reflected by the work W and received by the light-receiving portion. The light-receiving part is composed of, for example, a CCD sensor, and measures the distance from the laser sensor 3 to the workpiece W within the visual field range.

The sensor control unit 31 is a controller that controls the laser sensor 3 and transmits information including measured values of the laser sensor 3 to the robot control device 1 . The sensor control unit 31 calculates groove information including the cross-sectional shape of the workpiece W, for example, based on distance measurement data (distance information) measured in the process of determining the target position (target coordinates) of the welding torch 22. . The sensor control unit 31 transmits the target position and groove information to the robot control device 1 . Note that the function of the sensor control unit 31 may be included in the function of the control unit 11 of the robot control device 1 .

The photographing terminal 4 is, for example, a 3D camera having a 3D laser scanner function, but may be a portable terminal with a 3D camera. Portable terminals include, for example, portable terminals such as tablet terminals, smart phones, personal digital assistants (PDAs), and notebook PCs (personal computers). In order to fix the positional relationship with the workpiece W to be photographed, the photographing terminal 4 is preferably fixed at a predetermined position, orientation, and posture.

In order to implement the 3D laser scanner function, for example, a LiDAR (Light Detection and Ranging) sensor, a millimeter wave sensor, an ultrasonic sensor, etc. can be equipped.

The photographing terminal control unit 41 is a controller that controls the photographing terminal 4 and transmits information including photographed image data of the photographing terminal 4 to the robot control device 1 . The photographing terminal control unit 41 transmits, for example, three-dimensional image data including the work W photographed by the photographing terminal 4 to the robot control device 1 . Note that the functions of the imaging terminal control unit 41 may be included in the functions of the control unit 11 of the robot control device 1 .

FIG. 2 is a diagram illustrating the functional configuration of the robot control device 1 according to the present invention. The robot control device 1 has, for example, a point cloud data detection unit 111, an error calculation unit 112, and a sensor control unit 113 as functional configurations.

The point cloud data detection unit 111 detects point cloud data corresponding to the work W from three-dimensional image data including the work W photographed by the photographing terminal 4 . Specifically, the point cloud data detection unit 111 detects three-dimensional coordinate data corresponding to the workpiece W included in the image data based on the three-dimensional camera coordinate system, and uses this coordinate data as workpiece point cloud data. do. A three-dimensional camera coordinate system can be set, for example, with the center of the lens of the photographing terminal 4 as the origin.

The error calculator 112 compares the workpiece point cloud data detected by the point cloud data detector 111 and the reference point cloud data to calculate an error. The reference point cloud data is point cloud data corresponding to the reference work W arranged according to the reference position, orientation, and orientation. It is preferable that the reference point cloud data is detected in advance using the workpiece W as a reference and stored in the storage unit 12 . An example of the error calculation method will be described in (a) and (b) below.

(a) Create an approximation plane based on the reference point cloud data, calculate the distance between the approximation plane and each point included in the workpiece point cloud data, and use the average value of the calculated distances as an error. calculate. The distance between the approximation plane and each point of the workpiece point cloud data can be obtained as the length of the perpendicular drawn from each point to the approximation plane. can be calculated using This method can reduce the amount of calculation when calculating the error compared to the method (b) below.

(b) Calculate the distances between points having corresponding positional relationships in the workpiece point cloud data and the reference point cloud data, and calculate the average value of the calculated distances as an error. Although this method requires more calculation than the above method (a), it can improve the accuracy of error calculation.

When calculating the average value of the distances in (a) and (b) above, it is preferable to use the absolute value of the distances. As a result, even if there is variation in each point of the point cloud data, it is possible to cancel out the variation, so it is possible to improve the accuracy of error calculation.

The error calculation method is not limited to the above methods (a) and (b), and for example, the maximum distance among the distances within the reference may be extracted as the error.

When the sensor control unit 113 causes the laser sensor 3 to start sensing the workpiece W, the sensor control unit 113 causes the sensing start position corresponding to the error calculated by the error calculation unit 112 to start.

The sensing start position indicates that the manipulator 2 including the laser sensor 3 does not interfere (contact) the work W even when the laser sensor 3 moves from the start position toward the work W by a distance corresponding to the error. It is preferable to set it as a standard. As a result, even if the workpiece W deviates from the reference position by the amount corresponding to the error, the sensing start position can be shifted according to the error. It is possible to move without interfering with

The correspondence relationship between the error and the sensing start position is set according to the visual field range of the laser sensor 3 . For example, as shown in FIG. 3, the case where the visual field range V of the laser sensor 3 is 40 to 60 [mm] will be described. In this case, the laser sensor 3 can detect the workpiece W when the distance between the laser sensor 3 and the workpiece W is within the visual field range V of 40 to 60 [mm].

With reference to FIG. 4, the correspondence relationship between the settable error and the sensing start position when the visual field range V of the laser sensor 3 is 40 to 60 [mm] will be described. As shown in the figure, for example, (1) when the error calculated by the error calculator 112 is 0 to 5 [mm], the sensing start position is set to a position 50 [mm] away from the workpiece W. (2) If the error is 5 to 10 [mm], set the sensing start position to a position 60 [mm] away from the work W, (3) If the error is 10 to 20 [mm], the sensing start position can be set at a position 70 [mm] away from the workpiece W. (1) to (3) will be described with reference to FIGS. 5 to 7. FIG.

(1) When the error calculated by the error calculator 112 is 0 to 5 [mm] As shown in FIG. set to In this case, even if there is a deviation of 5 [mm], which is the maximum error, from the 50 [mm] set for the sensing start position S, the actual sensing start position is 45 to 55 [mm] from the workpiece W. You will be placed in a distant position. Therefore, if sensing is started from the sensing start position S set to 50 [mm], even if a deviation of 5 [mm], which is the maximum error, occurs, the visual field range V of the laser sensor 3 is 40 to 60 [mm]. ], the workpiece W can be detected. This makes it possible to prevent the manipulator 2 including the laser sensor 3 from interfering with the work W because the work W cannot be detected.

(2) When the error calculated by the error calculator 112 is 5 to 10 [mm] As shown in FIG. set. In this case, even if there is a deviation of 10 [mm], which is the maximum error, from the set sensing start position S of 60 [mm], the actual sensing start position is 50 to 70 [mm] from the workpiece W. You will be placed in a distant position. Therefore, by starting sensing from the sensing start position S set to 60 [mm] and repeating sensing while moving in a direction approaching the work W, the visual field range V of the laser sensor 3, 40 to 60 [mm], is obtained. It becomes possible to detect the workpiece W within the range.

(3) When the error calculated by the error calculator 112 is 10 to 20 [mm] As shown in FIG. In this case, even if there is a deviation of 20 [mm], which is the maximum error, from the set sensing start position S of 70 [mm], the actual sensing start position is 50 to 90 [mm] from the workpiece W. You will be placed in a distant position. Therefore, by starting sensing from the sensing start position S set to 70 [mm] and repeating sensing while moving in a direction approaching the work W, the visual field range V of the laser sensor 3, 40 to 60 [mm], is obtained. It becomes possible to detect the workpiece W within the range.

Even when the error calculated by the error calculating unit 112 exceeds 20 [mm], as in (1) to (3) above, even when the deviation of the maximum error occurs, the actual sensing start position The sensing start position S may be set such that the minimum value falls within the visual field range V. FIG. This makes it possible to prevent the manipulator 2 including the laser sensor 3 from interfering with the work W because the work W cannot be detected.

Returning to the description of FIG. The sensor control unit 113 performs sensing while moving the laser sensor 3 in a direction approaching the work W, and stops the movement of the laser sensor 3 when the work W is detected. As a result, the laser sensor 3 can be stopped when the purpose of sensing is achieved, so interference with the workpiece W can be reliably avoided.

When the laser sensor 3 moves a predetermined distance from the sensing start position toward the work W, the sensor control unit 113 stops the movement of the laser sensor 3 and displays an error message indicating that the work W could not be detected. Output. The output destination of the error message may be, for example, a display device such as a display, or a loudspeaker device such as a speaker.

The predetermined distance is determined, for example, by taking into account the error, the sensing start position S, and the visual field range V. It is preferable to set it within a range in which it does not occur. As a result, even if sensing cannot be performed normally, the laser sensor 3 can be stopped when the laser sensor 3 moves a predetermined distance, so that interference with the workpiece W can be reliably avoided. becomes possible.

As described above, according to the robot control device 1 according to the embodiment, the three-dimensional workpiece point cloud data corresponding to the workpiece W detected from the three-dimensional image data including the workpiece W and the reference point cloud data are generated. By comparison, an error representing the deviation from the reference position is calculated, and the laser sensor 3 can start sensing from the sensing start position S corresponding to the error. As a result, even if the workpiece W is displaced from the reference position by the amount of the error, the sensing start position S of the laser sensor 3 can also be displaced according to the error, thereby improving the efficiency of the sensing work. Moreover, since the photographing terminal 4 may be a camera capable of photographing three-dimensional image data, there is no need to use an expensive 3D camera.

Therefore, according to the robot control device 1 according to the embodiment, it is possible to shorten the tact time while suppressing the cost.

[Modification]
It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented in various other forms without departing from the gist of the present invention. Therefore, the above-described embodiment is merely an example in all respects, and should not be construed as limiting.

For example, in the above-described embodiment, the photographing terminal 4 is fixed at a predetermined position, orientation, and posture. good. In this case, it is preferable to store the reference point cloud data in advance in association with the photographing position.

Moreover, in the above-described embodiment, the case where the present invention is applied to a welding robot has been described, but the present invention is not limited to this. For example, the present invention can be applied to industrial robots including handling robots that perform picking and the like.

Furthermore, in the above-described embodiments, the laser sensor is used for explanation, but the present invention can also be applied to sensors other than the laser sensor. For example, a touch sensor may be used. Even when a touch sensor is used, the sensing start position of the touch sensor can be changed according to the error.

DESCRIPTION OF SYMBOLS 1... Robot control apparatus, 2... Manipulator, 3... Laser sensor, 4... Imaging terminal, 11... Control part, 12... Storage part, 13... Communication part, 14... Welding power supply part, 21... Articulated arm, 22... Welding Torch 31 Sensor control unit 41 Shooting terminal control unit 100 Robot system 111 Point cloud data detection unit 112 Error calculation unit 113 Sensor control unit S Sensing start position V Visual field range , W... work

Claims (5)

a point cloud data detection unit that detects, as object point cloud data, three-dimensional coordinate data corresponding to the object from three-dimensional image data including the object that the industrial robot is working on;
an error calculation unit that compares the detected object point cloud data with reference point cloud data that is stored in advance and calculates an error;
a sensor control unit that causes the sensor to start sensing in a direction approaching the object from a sensing start position corresponding to the calculated error;
A robot controller comprising: The error calculation unit calculates the error based on the distance between the object point cloud data and the reference point cloud data.
The robot controller according to claim 1. The error calculation unit calculates a distance between each point included in the object point cloud data and an approximate plane corresponding to the reference point cloud data, and uses an average value of the calculated distances as the error. calculate,
3. The robot controller according to claim 2. The error calculation unit calculates a distance between points having a corresponding positional relationship in the object point cloud data and the reference point cloud data, and calculates an average value of the calculated distances as the error.
3. The robot controller according to claim 2. The sensing start position is such that the industrial robot including the sensor does not interfere with the object even when the sensor moves a distance corresponding to the error from the sensing start position toward the object. is set on the basis of
The robot controller according to any one of claims 1 to 4.

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