Interference avoidance device and robot system

文档序号:1396712 发布日期:2020-03-03 浏览:6次 中文

阅读说明:本技术 干涉回避装置以及机器人系统 (Interference avoidance device and robot system ) 是由 藁科文和 並木勇太 小窪恭平 于 2019-08-20 设计创作,主要内容包括:本发明提供一种干涉回避装置以及机器人系统,能够准确且简便地获取应该回避的周围物体的位置,并且可靠地回避机器人与周围物体的干涉。干涉回避装置(3)具备:三维传感器(13),其安装于机器人臂的前端部,并且获取机器人(1)周围的距离图像;位置数据创建部(15),其将距离图像中的周围物体的坐标转换为机器人坐标系中的坐标,并且基于机器人坐标系中的周围物体的坐标,创建周围物体的位置数据(23);存储部(12),其存储位置数据(23);以及控制部(11),其基于机器人坐标系控制机器人(1),控制部(11)基于存储于存储部(12)的位置数据(23),以回避机器人(1)与周围物体的干涉的方式控制机器人(1)。(The invention provides an interference avoidance device and a robot system, which can accurately and simply acquire the position of a peripheral object to be avoided and reliably avoid the interference between a robot and the peripheral object. The interference avoidance device (3) is provided with: a three-dimensional sensor (13) that is attached to the tip of the robot arm and that acquires a distance image around the robot (1); a position data creation unit (15) that converts the coordinates of the surrounding object in the range image into coordinates in the robot coordinate system, and creates position data (23) of the surrounding object based on the coordinates of the surrounding object in the robot coordinate system; a storage unit (12) that stores position data (23); and a control unit (11) that controls the robot (1) on the basis of the robot coordinate system, wherein the control unit (11) controls the robot (1) so as to avoid interference between the robot (1) and surrounding objects on the basis of the position data (23) stored in the storage unit (12).)

1. An interference avoiding device, characterized in that interference between a robot and a peripheral object arranged around the robot is avoided,

the interference avoidance device includes:

a three-dimensional sensor that is attached to a distal end portion of a robot arm of the robot and acquires a distance image around the robot;

a position data creation unit that converts coordinates of the surrounding object in the distance image into coordinates in a robot coordinate system, and creates position data of the surrounding object based on the coordinates of the surrounding object in the robot coordinate system;

a storage unit that stores the position data; and

a control unit that controls the robot based on the robot coordinate system,

the control unit controls the robot so as to avoid interference between the robot and the surrounding object based on the position data of the surrounding object stored in the storage unit.

2. The interference avoidance device of claim 1,

the position data creating section determines whether or not each of the coordinates of the surrounding object in the robot coordinate system is a self-coordinate of the robot, the self-coordinate being a coordinate of the robot in the robot coordinate system at the time of acquiring the distance image,

the position data is created based on the coordinates of the peripheral object in the robot coordinate system other than the coordinates of the peripheral object as the own coordinates.

3. The interference avoidance device of claim 1 or 2,

the robot arm includes a plurality of joints, and the position and posture of the three-dimensional sensor can be three-dimensionally changed by the operation of the plurality of joints,

the control unit causes the three-dimensional sensor to acquire the distance image while causing the plurality of joints of the robot arm to operate.

4. The interference avoidance device of any one of claims 1 to 3,

the three-dimensional sensor acquires the range image including the range of the entire action area of the robot.

5. A robot system is characterized by comprising:

a robot having a robot arm; and

the interference avoidance device of any one of claims 1 to 4.

Technical Field

The present invention relates to an interference avoidance device and a robot system.

Background

Conventionally, a robot system having a function of avoiding interference between a robot and a surrounding object is known (for example, see patent documents 1 to 4).

In patent documents 1 to 3, the position of a workpiece and an object near the workpiece is detected by a sensor at the tip of a robot arm, and the position of a hand is controlled so that the hand does not interfere with the object.

In patent document 4, in order to avoid interference between a robot and an obstacle around the robot, a 3D camera is used to acquire a captured image of a region around the robot, and an interference region in which the obstacle exists is set based on the captured image. Thereafter, the robot is controlled so as to be inhibited from moving into the interference area. In patent document 4, a 3D camera is used to capture an image of a surrounding area including a robot from the outside of the robot. The robot is attached with a mark for identifying the robot in the captured image. Coordinates of the obstacle in the captured image are converted into coordinates in the robot coordinate system based on the markers in the captured image.

Disclosure of Invention

Problems to be solved by the invention

As described above, in patent documents 1 to 3, the position of an object near a workpiece is detected during the operation of the robot. Therefore, the robot cannot avoid interference with surrounding obstacles.

In patent document 4, a plurality of captured images are acquired while changing the position and orientation of a 3D camera with respect to a robot. Therefore, the conversion of the coordinates of the obstacle in the captured image requires complicated calculation. In addition, the calculation of the complex coordinate conversion causes the positional accuracy of the obstacle in the robot coordinate system to become low.

The captured image is an image of the robot and the obstacle viewed from the periphery. Based on such a captured image, it is difficult to grasp the exact position of the obstacle viewed from the robot.

In addition, since the mark of the robot needs to be included in the imaging range of the 3D camera, the position and orientation of the 3D camera are limited. Therefore, a blind area of the 3D camera may be generated within the motion region of the robot. Since an object existing in the blind area is not set in the interference area, interference between such an object and the robot cannot be avoided.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an interference avoidance device and a robot system capable of accurately and easily acquiring the position of a peripheral object to be avoided and reliably avoiding interference between a robot and the peripheral object.

Means for solving the problems

In order to achieve the above object, the present invention provides the following aspects.

One aspect of the present invention is an interference avoidance device that avoids interference between a robot and a peripheral object disposed around the robot, the interference avoidance device including: a three-dimensional sensor that is attached to a distal end portion of a robot arm of the robot and acquires a distance image around the robot; a position data creation unit that converts coordinates of the surrounding object in the distance image into coordinates in a robot coordinate system, and creates position data of the surrounding object based on the coordinates of the surrounding object in the robot coordinate system; a storage unit that stores the position data; and a control unit that controls the robot based on the robot coordinate system, wherein the control unit controls the robot so as to avoid interference between the robot and the peripheral object based on the position data of the peripheral object stored in the storage unit.

According to this aspect, before the robot performs a work, the position data of the surrounding object is acquired by the three-dimensional sensor and the position data creating unit and stored in the storage unit. That is, a distance image around the robot is acquired by the three-dimensional sensor, and position data of a peripheral object in the robot coordinate system is created from the distance image by the position data creating unit. Thereafter, the robot performs work while avoiding interference with surrounding objects under the control of the control unit.

Since the three-dimensional sensor is attached to the distal end portion of the robot arm, accurate position data of a surrounding object can be easily acquired. Interference between the robot and the surrounding object can be reliably avoided based on such accurate position data.

That is, the accurate position and orientation of the three-dimensional sensor in the robot coordinate system at the time of acquiring the distance image are easily acquired from the control signal used by the control unit for controlling the robot. Therefore, the coordinates of the peripheral object in the range image can be converted into the coordinates of the robot coordinate system with high accuracy by simple calculation, and the accurate position of the peripheral object in the robot coordinate system can be acquired.

In addition, a range image of a surrounding object viewed from the robot is acquired by a three-dimensional sensor. Therefore, a blind area of the three-dimensional sensor does not occur in the operation region of the robot, and the presence of a peripheral object in the operation region can be accurately grasped. In addition, an accurate position of the peripheral object viewed from the robot can be obtained.

In the above aspect, the position data creating unit may determine whether each of the coordinates of the peripheral object in the robot coordinate system is a self coordinate of the robot, the self coordinate being a coordinate of the robot in the robot coordinate system at the time of acquiring the distance image, and create the position data based on the coordinates of the peripheral object in the robot coordinate system other than the coordinates of the peripheral object as the self coordinate.

A part of the robot can be included in the range image. The position of a part of the robot within the range image changes with the movement of the robot. Therefore, when the positional data of a part of the robot in the distance image is stored in the storage unit, the control unit erroneously recognizes that a peripheral object is present at the position of the part of the robot at the time of acquiring the distance image, and controls the robot to avoid the position. According to the above configuration, such erroneous recognition can be prevented, and unnecessary avoidance operation of the robot can be eliminated.

In the above aspect, the robot arm may include a plurality of joints, and the position and posture of the three-dimensional sensor may be three-dimensionally changed by operations of the plurality of joints, and the control unit may cause the three-dimensional sensor to acquire the distance image while causing the plurality of joints of the robot arm to operate.

With this configuration, a wide range of distance images around the robot can be acquired by using one three-dimensional sensor.

In the above aspect, the three-dimensional sensor may acquire the distance image including a range of the entire motion region of the robot.

According to this configuration, the coordinates of all the peripheral objects in the operation area where the robot in operation can be arranged are acquired from the distance image, and the position data on all the peripheral objects is stored in the storage unit. This makes it possible to more reliably avoid interference between the robot and surrounding objects.

Another aspect of the present invention is a robot system including: a robot having a robot arm; and the interference avoiding device according to any one of the above.

Effects of the invention

According to the present invention, the following effects are obtained: the position of a peripheral object to be avoided can be accurately and easily acquired, and interference between the robot and the peripheral object can be reliably avoided.

Drawings

Fig. 1 is an overall configuration diagram of a robot system according to an embodiment of the present invention.

Fig. 2 is a block diagram of the robotic system of fig. 1.

Fig. 3 is a flowchart showing an operation of the robot system of fig. 1.

Description of the reference numerals

1: robot

2: control device

3: interference avoiding device

4: robot arm

5: base station

10: robot system

11: robot control unit

12: storage unit

13: three-dimensional sensor

14: sensor control unit

15: position data creating unit

21: action program

22: position data creation program

23: position data

Detailed Description

The interference avoiding device and the robot system according to one embodiment of the present invention will be described below with reference to the drawings.

As shown in fig. 1, a robot system 10 according to the present embodiment controls a robot 1 so as to avoid interference between the robot 1 and a peripheral object O during work in an environment in which the peripheral object O is disposed around the robot 1. The peripheral object O is, for example, a device, another robot, a structure, or the like. As shown in fig. 1 and 2, the robot system 10 includes: a robot 1; a control device 2 connected to the robot 1; and an interference avoidance device 3 that avoids interference between the robot 1 and the peripheral object O.

The robot 1 is, for example, a six-axis articulated robot. The robot 1 has a robot arm 4 provided with a plurality of joints, and the position and posture of the tip of the robot arm 4 can be changed three-dimensionally by the action of the joints. The position and posture of a three-dimensional sensor 13 (to be described later) attached to the distal end portion of the robot arm 4 are also changed together with the distal end of the robot arm 4. Each joint is provided with a servomotor (not shown), and each servomotor rotates the corresponding joint in accordance with a robot control signal from the control device 2. An end effector (not shown) such as a hand or a tool is attached to a wrist flange at the distal end of the robot arm 4. The robot 1 performs a predetermined operation such as conveyance or processing of a workpiece by using an end effector.

A robot coordinate system a is defined in the robot 1. The robot coordinate system a is a three-dimensional coordinate system having a predetermined position of a stationary part of the robot (for example, the center of the installation surface of the base 5) as an origin.

As shown in fig. 2, the control device 2 includes: a robot control unit 11 having a processor; and a storage unit 12 having a RAM, a ROM, a nonvolatile memory, and the like.

The storage unit 12 stores an operation program 21. The robot control unit 11 generates a robot control signal for driving each servomotor based on the operation program 21, and transmits the robot control signal to each servomotor. Thereby, the robot arm 4 operates based on the operation program 21. The robot control unit 11 controls the robot 1 using the coordinates in the robot coordinate system a.

The interference avoidance device 3 includes a three-dimensional sensor 13, a sensor control unit 14, and a position data creation unit 15. The sensor control unit 14 and the position data creating unit 15 are provided in the control device 2, for example. The robot control unit (control unit) 11 and the storage unit 12 also function as a part of the interference avoidance device 3.

The three-dimensional sensor 13 is attached to the distal end portion of the robot arm 4. For example, the three-dimensional sensor 13 is a stereo camera having a pair of cameras. The stereo camera calculates a distance between an object in a stereo image acquired by a pair of cameras and the stereo camera from the stereo image, and generates a distance image. For example, the three-dimensional sensor 13 is a visual sensor that is mounted to a wrist flange together with the end effector and observes a workpiece held or processed by the end effector. The three-dimensional sensor 13 may also be a laser range finder that outputs laser light and calculates the distance of an object from the reflection position and the reflection time of the laser light.

The three-dimensional sensor 13 acquires a range image around the robot 1. The distance image is an image in which each pixel has information of the distance from the three-dimensional sensor 13 to the object. Preferably, the imaging range of the distance image includes the entire operation area where the robot 1 can be arranged during the work. Such a wide-range image is obtained by three-dimensionally changing the position and orientation of the three-dimensional sensor 13 while directing the three-dimensional sensor 13 to the outside of the robot 1 by the motion of the robot arm 4, and acquiring range images at a plurality of positions and orientations by the three-dimensional sensor 13. The distance image is transmitted from the three-dimensional sensor 13 to the control device 2 and stored in the storage unit 12.

A sensor coordinate system B is defined in the three-dimensional sensor 13. The sensor coordinate system B is a three-dimensional coordinate system having a predetermined position of the three-dimensional sensor 13 as an origin. The coordinates of the object within the range image are the coordinates in the sensor coordinate system B.

The sensor control unit 14 controls the three-dimensional sensor 13. The sensor control unit 14 causes the three-dimensional sensor 13 to perform imaging in response to a sensor control signal from the robot control unit 11, and causes the three-dimensional sensor 13 to acquire a distance image in synchronization with the movement of the robot arm 4.

The position data creating unit 15 has a processor, and executes the following processing based on a position data creating program 22 to be described later. The position data creation section 15 reads the range image from the storage section 12, and acquires the three-dimensional coordinates of the surface of the surrounding object O within the range image. The acquired coordinates are coordinates in the sensor coordinate system B. Next, the position data creation section 15 converts the coordinates of the surface of the surrounding object O into coordinates in the robot coordinate system a based on the position and orientation of the three-dimensional sensor 13 in the robot coordinate system a at the time of acquiring the distance image.

The position and posture of the three-dimensional sensor 13 in the robot coordinate a at the time of acquiring the distance image are calculated from the position and posture of the distal end of the robot arm 4 at the time of acquiring the distance image and the position and posture of the three-dimensional sensor 13 with respect to the distal end of the robot arm 4. The position and posture of the tip of the robot arm 4 are calculated from the robot control signal. These calculations are performed by the robot control unit 11 or the position data creation unit 15, for example.

Next, the position data creating unit 15 creates the position data 23 of the peripheral object O based on the three-dimensional coordinates of the peripheral object O in the robot coordinate system a. The position data 23 is, for example, a set of coordinates of the surface of the surrounding object O in the robot coordinate system a.

The storage unit 12 stores a position data creation program 22. The robot control unit 11 generates a robot control signal and a sensor control signal based on the position data creation program 22. The robot control unit 11 transmits a robot control signal to each servomotor and a sensor control signal to the sensor control unit 14. Thereby, the robot arm 4 operates based on the position data creation program 22, and the three-dimensional sensor 13 acquires a distance image based on the position data creation program 22.

The robot control unit 11 generates a robot control signal for moving the distal end of the robot arm 4 to the target position in accordance with the operation program 21. The robot control unit 11 predicts whether the robot 1 will interfere with the peripheral object O until the leading end reaches the target position based on the position data 23 before transmitting the robot control signal to the robot 1. When it is predicted that the robot 1 does not interfere with the surrounding object O, the robot control unit 11 transmits a robot control signal to the robot 1 to move the tip of the robot arm 4 to the target position. On the other hand, when it is predicted that the robot 1 interferes with the peripheral object O, the robot control unit 11 controls the robot 1 so as to avoid the interference between the robot 1 and the peripheral object O. For example, the robot control unit 11 stops transmitting the robot control signal to the robot 1 to stop the operation of the robot 1.

The interference between the robot 1 and the surrounding object O is predicted, for example, in the following order.

The storage unit 12 stores, as the position data 23, the coordinates Pi of the surface of the peripheral object O (Xi, Yi, Zi) (i 1, 2, …, n). The coordinates Pi are the coordinates in the robot coordinate system a. The robot control unit 11 defines the three-dimensional shape of the robot 1 as a plurality of columnar regions Cj (j is 1, 2, …, m). That is, the three-dimensional shape of the robot 1 is expressed as a combination of the plurality of regions Cj. Actually, since it is difficult to accurately represent the three-dimensional shape of the robot 1 by the combination of the plurality of regions Cj, the regions Cj are set so that the entire robot 1 is included in the combination of the plurality of regions Cj.

The robot control unit 11 calculates the three-dimensional shape Cj of the robot 1 when the robot arm 4 is assumed to operate in accordance with the robot control signal. Then, the robot control unit 11 calculates whether or not (i, j) satisfying Pi ∈ Cj exists for i ∈ 1, 2, …, n, and j ═ 1, 2, …, and m. If not, the robot control unit 11 predicts that the robot 1 does not interfere with the peripheral object O. On the other hand, if any, the robot control unit 11 predicts that the robot 1 interferes with the surrounding object O.

Next, an operation of the robot system 10 configured as described above will be described.

According to the robot system 10 of the present embodiment, the position data creation program 22 is executed, and then the operation program 21 is executed.

If the position data creation program 22 is executed, the position and posture of the three-dimensional sensor 13 are changed by the action of the robot arm 4 as shown in fig. 3, and the three-dimensional sensor 13 acquires distance images at a plurality of positions and postures. Thereby, a distance image around the robot 1 is acquired (step S1). The distance image is transmitted from the three-dimensional sensor 13 to the control device 2 and stored in the storage unit 12. Next, in the position data creating unit 15, the three-dimensional coordinates of the peripheral object O within the range image are acquired, the coordinates of the peripheral object O are converted into coordinates in the robot coordinate system a (step S2), and the position data 23 of the peripheral object O is created from the coordinates of the peripheral object O in the robot coordinate system a (step S3). The position data 23 is stored in the storage unit 12 (step S4).

The position data creation program 22 may be executed before each execution of the action program 21. Alternatively, the position data creation program 22 may be executed only after the environment around the robot 1 changes, such as after the robot 1 is moved or the configuration of the surrounding devices is changed.

Next, the action program 21 is executed. The robot control unit 11 causes the robot 1 to perform a predetermined operation in accordance with the operation program 21. The robot control unit 11 reads the position data 23 from the storage unit 12, and controls the robot 1 during the work so as to avoid interference between the robot arm 4 and the peripheral object O based on the position data 23. For example, the robot control unit 11 predicts whether the robot 1 will interfere with the surrounding object O on the next target position of the tip of the robot arm 4 or on the moving path to the target position, and stops the robot 1 when the prediction of interference is made.

As described above, according to the present embodiment, the distance image of the peripheral object O is acquired by the three-dimensional sensor 13 attached to the distal end portion of the robot arm 4. Has the following advantages: accurate position data 23 of the peripheral object O can be acquired based on the distance image, and interference between the robot 1 and the peripheral object O can be reliably avoided based on the accurate position data 23.

Specifically, in order to convert the position of the peripheral object O in the range image into a position in the robot coordinate system a, it is necessary to acquire information of the position and orientation of the three-dimensional sensor 13 in the robot coordinate system a at the time of the range image. According to the present embodiment, the accurate position and orientation of the three-dimensional sensor 13 in the robot coordinate system a are obtained by simple calculation from the robot control signal. Therefore, the accurate position of the peripheral object O in the robot coordinate system a can be calculated.

The distance image is an image of the peripheral object O viewed from the distal end of the robot arm 4. Therefore, a blind area that cannot be captured by the three-dimensional sensor 13 does not occur in the motion region of the robot 1, and the peripheral object O existing in the motion region can be reliably recognized from the range image. In addition, the accurate position of the peripheral object O observed from the robot 1 can be obtained from the range image.

Unlike the case where the distance image of the peripheral object O is acquired by the three-dimensional sensor arranged around the robot 1, the case where the distance image is acquired by the three-dimensional sensor 13 at the tip of the robot arm 4 is rare in which the robot 1 itself is imaged. However, a part of the robot 1 is included in the range image. When a part of the robot 1 in the range image is a movable part (for example, the robot arm 4) and the coordinates of the movable part are stored as the position data 23, the robot control unit 11 erroneously recognizes a three-dimensional area in which the movable part is arranged as the surrounding object O when acquiring the range image, and controls the robot 1 so as to avoid the area.

In order to prevent such unnecessary interference avoidance operation, the position data creating unit 15 may exclude a part of the coordinates of the robot 1 from the coordinates of the peripheral object O acquired in the range image, and create the position data 23 from the remaining coordinates.

The position data creating unit 15 determines whether or not the coordinates of the peripheral object O after the coordinate conversion is the coordinates of the movable part of the robot 1. The self coordinates of the movable portion of the robot 1 are coordinates in the robot coordinates a of the three-dimensional region in which the movable portion is arranged at the time of acquiring the distance image. The position data creating unit 15 creates the position data 23 based on the coordinates of the peripheral object O other than the coordinates of the peripheral object O as its own coordinates.

The coordinates of the robot 1 can be easily calculated from the robot control signals. Therefore, whether the object in the range image is the surrounding object O or part of the robot 1 can be easily determined. The coordinates of the robot 1 calculated by the position data creation program 22 may be stored in the storage unit 12 in advance.

In the present embodiment, the position data creating unit 15 may create the position data 23 including all the coordinates of the peripheral object O acquired from the range image, or may create the position data 23 from the remaining coordinates by removing the coordinates of the peripheral object O acquired from the range image at intervals. For example, in the case where two coordinates of the surrounding object O exist within a predetermined distance, only one coordinate may be used for the position data 23.

In this way, by reducing the number of coordinates included in the position data 23, the amount of information of the position data 23 can be reduced. In addition, the processing time required for the interference determination between the robot 1 and the peripheral object O can be reduced.

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