JP2022152460A - robot system - Google Patents

Abstract

To provide a robot system capable of detecting positions of all objects in a workpiece even when a size of an optical sensor is not selected according to the size of the workpiece.SOLUTION: A laser sensor 11 capable of detecting a position of an object captured in a detection range is arranged in a tip part of an arm of a robot 2, and a controller 3 controls the robot 2, and detects respective positions of a plurality of yarns 23 in a workpiece 22 based on a sensor signal input from the laser sensor 11. With this, when the arm of the robot 2 is moved in a direction where the plurality of yarns 23 are aligned, the arm is moved so that one end part of the detection range of the laser sensor 11 is overlapped, and when the overlappingly detected yarn 23 exists in a part of the detection range overlapped before and after the movement, the yarn 23 is excluded from position detection objects.SELECTED DRAWING: Figure 1

Description

The present invention relates to a system comprising a robot having an arm, an optical sensor arranged at the tip of the arm, and a control device that controls the robot and receives a sensor signal from the optical sensor.

In a system using a robot having an arm, it is common practice to detect the position of a work by a sensor and then perform work on the work.

JP 2018-144159 A

By the way, there are various shapes of workpieces handled by robots, and among them, for example, there are those in which a plurality of thread-like or string-like objects are lined up in a state of being stretched at intervals. In this case, each position where a plurality of threads are stretched is detected by a sensor before the work is performed.

However, as the number of objects in one work increases, the work becomes longer in the direction in which the objects are arranged. At that time, if the detection range of the sensor is matched to the length of the work, the size of the sensor becomes large, resulting in an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a robot system capable of detecting the positions of all objects in a workpiece without selecting the size of the optical sensor according to the size of the workpiece. to provide.

According to the robot system of claim 1, an optical sensor capable of detecting the position of an object captured within a detection range is arranged at the tip of the robot arm, and the control device controls the robot and controls the optical sensor. Each position of a plurality of objects in the workpiece is detected based on sensor signals input from the workpiece. At that time, the control device moves the arm of the robot in the direction in which the plurality of objects are aligned, but moves the arm so that one end of the detection range of the optical sensor overlaps. Then, if there is an object that is detected redundantly in the portion of the detection range that overlaps before and after the movement, that object is excluded from the detection targets.

With this kind of control, even if the optical sensor does not have a detection range that can capture all of the objects lined up on the workpiece at once, the control device can detect the positions of the objects. It can be detected without omission and without duplication.

According to the robot system of claim 2, the control device moves the arm so that an object detected at one end of the current detection range is also detected in the overlapping portion in the next detection range. This kind of control is possible if the approximate distance between the objects lined up on the workpiece is known in advance. By controlling in this way, objects that are at one end of the detection range can be detected more reliably without omission. can.

According to the robot system of claim 3, the control device moves the arm so as to detect the positions of all the objects on the one end side and the other end side where the plurality of objects are fixed to the workpiece. With this control, the position of each object can be accurately detected even when a plurality of objects are not aligned in parallel within the workpiece.

According to the robot system of claim 4, the tip of the arm is also provided with a tool for processing each object in the workpiece, and the control device also controls the robot for processing using the tool. With this configuration, the robot can perform a series of operations from position detection of each object to work using the tool, thereby improving work efficiency.

FIG. 1 is a perspective view showing the system configuration of one embodiment (part 1); Perspective view showing system configuration (Part 2) Functional block diagram showing system configuration Top view of workpiece 4 is a flow chart showing the gist of the processing performed by the controller; Control sequence diagram between robot, controller, and laser sensor A diagram for explaining the state in which the detection range of the laser sensor is moved with respect to the detection range A of the workpiece.

An embodiment will be described below with reference to the drawings. 1 and 2 show the system configuration of this embodiment including a general horizontal four-axis industrial robot. A robot system 1 is composed of a robot 2 and a controller 3 that controls the robot 2 . The controller 3 corresponds to a control device.

The robot 2 is, for example, a four-axis horizontal articulated robot. The robot 2 includes a base 5 fixed to an installation surface, a first arm 6 rotatably connected to the base 5 about a first axis J1 having a center axis in the Z-axis direction, which is a vertical axis, and a first arm. A second arm 7 is rotatably connected to the tip of the first arm 6 around a second axis J2 having an axis in the Z-axis direction. and a shaft 8 provided in the The axis for vertically moving the shaft 8 is the third axis J3, and the axis for rotating it is the fourth axis J4. A flange 9 is attached to the lower end of the shaft 8 .

Base 5 , first arm 6 , second arm 7 , shaft 8 and flange 9 function as arms of robot 2 . A plurality of axes J1 to J4 provided in the robot 2 are driven by motors (not shown) provided corresponding to the axes J1 to J4. A position detector (not shown) for detecting the rotation angle and rotation position of each rotary shaft is provided near each motor.

A substantially rectangular parallelepiped base member 10 is attached to a flange 9 as an arm tip, and a laser sensor 11 as an optical sensor is attached to one side surface of the base member 10 . A tool 12, which is a narrow tubular nozzle, is attached to the lower surface of the base member 10. As shown in FIG. FIG. 3 is a functional block diagram of the system configuration.

A work 22 having a rectangular frame shape is placed on the work table 21 . As shown in FIG. 4, a plurality of threads 23, which are objects to be detected, are stretched between the long sides of the workpiece 22 facing each other. That is, the upper and lower ends of the thread 23 are fixed to the upper and lower sides of the workpiece 22, respectively. The robot 2 is installed on a robot installation table 24 that is higher than the work table 21 . The size of the work 22 is, for example, 400 mm×700 mm.

Next, the operation of this embodiment will be described with reference to FIGS. 5 to 7. FIG. In this embodiment, it is assumed that the robot 2 is caused to perform the following work.
(1) The position of each thread 23 stretched on the work 22 is detected by the laser sensor 11 .
(2) The adhesive discharged from the tool 12 is applied to each thread 23 whose position has been detected.
(3) When the adhesive is applied to all threads 23, the next work 22 is replaced.
Thereafter, (1) to (3) are repeatedly executed. However, since the work related to the gist of the present embodiment is only (1), the following describes (1).

Three types of threads 23 with different thicknesses are stretched on the work 22 shown in FIG. As shown in FIG. 7, the total detection range is divided into A, B, and C according to the three types of yarn 23. FIG. Compared to the longitudinal distance of the detection range A of 240 mm, the length of the range that can be detected by the laser sensor 11 at one time is 65 mm, which is short. It is conceivable to use a laser sensor having a detection range of 240 mm or more, but in that case, the cost of constructing the system will increase. Therefore, in the present embodiment, the positions of all the threads 23 within the detection range A are detected by moving the laser sensor 11 in the longitudinal direction of the workpiece 22 multiple times.

In FIG. 7, the laser sensor 11 is shown to be moved four times in the horizontal direction in the figure for detection, but it is difficult to accurately set the irradiation width of the laser for the detection range after movement. Further, as shown in FIG. 4, the intervals between the threads 23 are not constant, but vary from 2 mm to 5 mm, for example. Therefore, the end portions of both detection ranges are set so as to overlap before and after movement, thereby avoiding omission of detection of the yarn 23 . The overlapping width is, for example, about 7 mm. This overlapping width is set so that the thread 23 detected at the right end of the detection range before movement is reliably detected even in the overlapping portion at the left end of the detection range after movement.

Further, since the threads 23 are not necessarily stretched in parallel, the adhesive cannot be applied to the entire threads 23 even if the position is detected only at one end of the workpiece 22 . Therefore, position detection is performed on both the lower end side and the upper end side of the workpiece 22 in each detection range. For example, regarding the detection range A, the lower end side is A1 and the upper end side is A2.

FIG. 5 is a flow chart showing a portion of the processing performed by the controller 3 according to the gist of the present embodiment. 6 shows a control sequence among the robot 2, controller 3 and laser sensor 11 corresponding to FIG. The controller 3 causes the robot 2 to move the reading position of the workpiece 22 by the laser sensor 11 (S 1 ), and outputs a reading instruction to the laser sensor 11 . The first reading position is the left end (1) of the detection range A1 in the drawing. The laser sensor 11 then returns the reading result to the controller 3 . As a result, the thread 23 within the reading position (1) is detected (S2). In the sensor signal waveform of the laser sensor 11 shown in FIG. 7, the yarn 23 is detected in the portion where the waveform rises in a pulse shape.

If reading of the detection range A1 is not completed (S3; NO), the process returns to step S1 to move the laser sensor 11 to the next reading position (2). When the above processing is repeated until the reading position (4) is detected (S3; YES), the robot 2 moves the reading position by the laser sensor 11 to the opposite side, that is, to the detection range A2 side (S4). In subsequent steps S5 to S7, the same processing as in steps S1 to S3 is performed for the detection range A2.

When the detection range A2 is detected up to the reading position (4) (S7; YES), the controller 3 converts the position of each thread 23 detected by the laser sensor 11 into robot coordinates based on the position of the robot 2. (S8). Then, if there is an overlapping robot coordinate due to the thread 23 being detected in the overlapped detection range before and after the laser sensor 11 is moved (S9; YES), the robot coordinate is removed from the recognition target. Exclude (S11). Robot coordinates that do not overlap (S9; NO) are used as they are for recognition (S10).

Since the number of yarns 23 existing within the detection range A is known, the process returns to step S9 until the processing for that number is completed (S12; NO). When the processing for the number of lines is completed (S12; YES), the reading of the detection range A ends. When the above processing is similarly performed for the detection ranges B and C, position detection of all the threads 23 with respect to the work 22 is completed. After that, the controller 3 causes the robot 2 to apply the adhesive to each thread 23 .

As described above, according to this embodiment, the laser sensor 11 capable of detecting the position of an object captured within the detection range is arranged at the tip of the arm of the robot 2, and the controller 3 controls the robot 2. At the same time, each position of a plurality of threads 23 in the work 22 is detected based on sensor signals input from the laser sensor 11 .

Therefore, when moving the arm of the robot 2 in the direction in which the threads 23 are arranged, the arm is moved so that one end of the detection range of the laser sensor 11 overlaps. Then, if there is a yarn 23 that is detected redundantly in the portion of the detection range that overlaps before and after the movement, the yarn 23 is excluded from the target of position detection.

With this control, even if the laser sensor 11 does not have a detection range for capturing all of the plurality of threads 23 aligned on the workpiece 22 at once, the controller 3 can detect each position of the plurality of threads 23. It can be detected without omission and without duplication.

Further, the controller 3 moves the arm of the robot 2 so that the yarn 23 detected at one end of the current detection range is also detected in the overlapping portion in the next detection range. Such control is possible by grasping in advance the approximate spacing of the threads 23 lined up on the workpiece 22, and by controlling in this way, the threads 23 that overlap one end of the detection range can be detected without omission. can be reliably detected.

Further, the controller 3 moves the arm so as to detect the positions of all the threads 23 on the lower end side and the upper end side where the plurality of threads 23 are fixed to the workpiece 22 . With this control, the position of each thread 23 can be accurately detected even when the plurality of threads 23 are not aligned in parallel within the workpiece 22 .

In addition, the tip of the arm is equipped with a tool 12 for processing each yarn 23 in the workpiece 22, and the controller 3 also controls the robot 2 for processing using the tool 12. , detection of the position of each thread 23 to work using the tool 12 can be performed as a series of operations, and work efficiency is improved.

The present invention is not limited to the embodiments described above or illustrated in the drawings, but can be modified or expanded as follows.
Only one type of thread 23 may be arranged on the work 22 .
The number of times the detection range of the laser sensor 11 is moved is not limited to four, and may be changed as appropriate according to individual designs.
It is not necessary to set overlapping ranges such that the yarn 23 detected at the end of the detection range before movement is also detected at the end of the detection range after movement.

Specific numerical values are only examples.
The work performed by the robot 2 after position detection is not limited to applying adhesive.
If it is sufficient to detect the position of only one end depending on the length of the object to be detected and the type of work performed by the robot, position detection does not necessarily need to be performed on both ends of the workpiece.
The optical sensor is not limited to the laser sensor 11, and any sensor capable of detecting the position of the thread 23 may be used.
The object to be detected is not limited to the thread 23 .
The robot is not limited to a horizontal 4-axis type, but may be a vertical 6-axis type, for example.

In the drawings, 1 is a robot system, 2 is a robot, 3 is a controller, 11 is a laser sensor, 12 is a tool, 22 is a work, and 23 is a thread.

Claims (4)

a robot having an arm;
an optical sensor that is arranged at the tip of the arm and capable of detecting the position of the object captured within a detection range for a workpiece in which a plurality of objects are arranged so as to be spaced apart;
a control device that controls the robot and detects each position of the plurality of objects based on sensor signals input from the optical sensor;
The control device moves the arm of the robot in the direction in which the plurality of objects are arranged to detect the positions of all the objects on the workpiece, and the detection range of the optical sensor overlaps at one end. a robot system that moves the arm as described above, and excludes the object from the target of position detection when an object that is detected redundantly in a portion of the detection range that overlaps before and after the movement is present. 2. The robot system according to claim 1, wherein the control device moves the arm so that an object detected at one end of a current detection range is also detected at an overlapping portion in the next detection range. 3. The robot according to claim 1, wherein the control device moves the arm so as to detect the positions of all objects on one end side and the other end side where the plurality of objects are fixed to the work. system. A tool for processing each of the objects is provided at the tip of the arm,
The robot system according to any one of claims 1 to 3, wherein the control device also controls the robot for processing using the tool.

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