Robot control device, robot control system, and robot control method

A robot control device is configured to control a robot operating in a shared work area with an operator. The robot control device includes a distance estimation unit configured to obtain a reachable range of the operator on the basis of information on position and information on physical characteristics of the operator, and obtain a distance between the reachable range and the robot on the basis of information on position and information on shape of the robot and the reachable range, an interference probability calculation unit configured to obtain an interference probability between the robot and the operator on the basis of the distance, and an operation control unit configured to control operation of the robot on the basis of the interference probability.

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2018-237097, filed on 19 Dec. 2018, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a robot control device, a robot control system, and a robot control method for controlling a robot, and more specifically relates to a robot control device, a robot control system and a robot control method for controlling a robot operating in a shared work area with an operator.

Related Art

Conventionally, in the field of an industrial robot and the like, a robot and an operator work in a work area shared with each other in some case, in order to increase the efficiency of production and assembly. In this case, it is undesirable that the robot and the operator may interfere with each other, and the robot and the operator may come into contact with each other in the work area. A prior art for preventing such interference from occurring is known (refer to, for example, Patent Document 1).

Patent Document 1 discloses that “A robot control device is configured to control a robot working in a shared workspace with an operator performing at least one work process with the work action set previously. The robot control device comprises a robot control state measuring unit that measures a robot control state that includes the position and the posture of a robot; a work area setting unit that stores, for each work process, an area that contains the space occupied by the body of an operator in work actions performed by the operator from the start to the end of the work process, and that sets a work area corresponding to the current work process of the operator on the basis of a work process specifying signal that specifies the work process that is currently being performed by the operator; and a robot command generating unit that generates an operation command for the robot on the basis of the work area and the robot control state. The robot command generating unit changes the operation command for the robot in accordance with whether the robot is inside the work area.

Patent Document 1: Pamphlet of PCT International Publication No. WO2017/203937

SUMMARY OF THE INVENTION

In the case where a robot and an operator work in a shared work area, the operator may perform an action unrelated to the work operation, for example, an action of unexpectedly stretching out the arm. Taking into consideration such a case, a technique for preventing such interference from occurring between the robot and the operator is desired.

(1) A robot control device according to one aspect of the present disclosure (for example, a robot control device100to be described below) is configured to control a robot operating in a shared work area with an operator. The robot control device includes a distance estimation unit (for example, a distance estimation unit102to be described below) configured to obtain a reachable range of the operator on the basis of information on position and information on physical characteristics of the operator, and obtain a distance between the reachable range and the robot, on the basis of information on position and information on shape of the robot and the reachable range, an interference probability calculation unit (for example, an interference probability calculation unit103to be described below) configured to obtain an interference probability between the robot and the operator on the basis of the distance, and an operation control unit (for example, an operation control unit104to be described below) configured to control operation of the robot on the basis of the interference probability.

(2) In the robot control device according to (1), the operation control unit may determine a speed of an arm of the robot on the basis of the interference probability.

(3) In the robot control device according to (2), the operation control unit may determine the speed of the arm of the robot depending on a moving direction of the arm of the robot.

(4) in the robot control device according to any one of (1) to (3), a bar code or a QR code (registered trademark) (for example, a QR code420or210) may be attached to the operator and the robot, respectively, and the bar code or the QR code (for example, a QR code420) attached to the operator may include information indicating an operator ID and physical characteristics of the operator, and the bar code or the QR code (for example, a QR code210) attached to the robot may include information indicating a robot ID and a robot size.

(5) A robot control system according to one aspect of the present disclosure includes the robot control device according to any one of (1) to (4), a robot configured to be controlled by the robot control device, and a camera configured to capture images of an operator and the robot.

(6) A robot control method according to one aspect of the present disclosure is provided for a robot control device (for example, a robot control device100to be described below) configured to control a robot operating in a shared work area with an operator. The robot control method includes the steps of obtaining a reachable range of the operator on the basis of information on position and information on physical characteristics of the operator, obtaining a distance between the reachable range and the robot on the basis of information on position and information on shape or the robot and the reachable range, obtaining an interference probability between the robot and the operator on the basis of the distance, and controlling operation of the robot on the basis of the interference probability.

One aspect of the present disclosure enables to make a robot operate so as to avoid interference from occurring between an operator and the robot even when the operator performs an action unrelated to work operation.

DETAILED DESCRIPTION OF THE INVENTION

<Overall Configuration of Embodiment>

The overall configuration of a robot control system10according to the present embodiment is described first by referring toFIG. 1. As shown inFIG. 1, the robot control system10includes a robot control device100, a robot200and a camera300. An operator400and a work table501are illustrated in the drawing. The operator400wears a working cap (also referred to as a protective cap)410with a QR code (registered trademark)420attached to the head top.

The robot control device100and the robot200are communicably connected to each other. The robot control device100and the camera300are also communicably connected to each other. Such connection may be wired connection via signal lines or wireless connection. Alternatively, such connection may be performed via, for example, a network such as a LAN (local area network) or the Internet. The robot control device100mutually communicate with the robot200and the camera300by such connection.

The robot control device100is configured to control the operation of the robot200. The robot control device100includes various functional blocks for controlling the operation of the robot200. These functional blocks will be detailed below by referring toFIG. 4. The robot control device100is realized by adding a function specific to the present embodiment to a general robot control device (robot controller).

The robot200is configured to be operated on the basis of the control by the robot control device100. The robot200includes movable parts operated on the basis of the control by the robot control device100, such as an arm and an end effector (for example, a gripper for gripping a workpiece). A QR code (registered trademark)210is provided at the tip of the end effector of the robot control device100. The robot200is a general industrial robot for use in a factory in which, for example, automobiles, home electric appliances, or electronic components are manufactured.

The camera300is configured to capture images of an operator and a robot in the vicinity of the work table501. The camera300is installed, for example, on a ceiling so as to be able to capture images of the QR code210provided at the tip of the end effector of the robot200and the QR code420attached to the head top of the working cap410, when the robot200and the operator400are positioned in the vicinity of the work table501. The image data captured by the camera300is output to the robot control device100. It is noted that, although the case of one unit of the camera300provided is described in the present embodiment, a plurality of cameras may be provided.

The QR code210includes information such as a robot ID (for example, a robot identification number) and a robot size. The information on robot size includes information such as the lengths of an arm and an end effector, and the diameters of the arm and the end effector. The QR code420includes information such as an ID (for example, operator identification number) and physical characteristics of an operator. The information on physical characteristics of operator includes a shoulder width and the lengths of left and right arms, and thus by use of such information, the span of operator's arms is able to be calculated. The QR code420may include a span of operator's arms as information on physical characteristics. The QR code210and the OR code420may be of bar codes.

FIG. 2shows the functional blocks of the robot control device according to the embodiment of the present invention. As shown inFIG. 2, the robot control device100includes an information acquisition unit101, a distance estimation unit102, an interference probability calculation unit103, and an operation control unit104.

The information acquisition unit101acquires the image data including the QR code (registered trademark)210and the QR code420from the camera300, and transmits the image data to the distance estimation unit102.

The distance estimation unit102obtains a distance d between the robot200and the reachable range of the operator400by using the image data. The distance is obtained by the following steps (1) to (4).(1) The distance estimation unit102obtains the position of the tip of the end effector of the robot200and the position of the head top of the working cap of the operator400, by detecting the positions of the QR code210and the QR code420having square shapes in the imaging area of the camera300.(2) The distance estimation unit102reads the information on physical characteristics of the operator400described in the QR code420, for example, the shoulder width and the lengths of the left and right arms, and calculates the span of the arms of the operator400. The distance estimation unit102obtains a reachable range A of the operator400shown inFIG. 3, on the basis of the position of the QR code420and the span of the arms of the operator400. In the present embodiment, the circular range centering on the position of the QR code420of the operator when the operator400spreads out the arms is set as the reachable range. Alternatively, taking into consideration the case where the operator400stretches out the hand when stooping, a range wider than the range of the span of the arms of the operator400may be set as the reachable range. It is noted that, since the operator400rarely stretches out the hand rearward in general during operation, a semicircular range on the front side (chest side) of the operator may be set as the reachable range.(3) The distance estimation unit102reads information on robot shape described in the QR code210, for example, the lengths of the arm and the end effector, and the diameters of the arm and the end effector, and obtains a straight line L which passes the side surface of the arm or the end effector positioned closest to the operator400, on the basis of the read information and the position of the QR code210.(4) The distance estimation unit102obtains the distance d between the obtained straight-line L and the reachable range A of the hand, as shown inFIG. 3. The distance d corresponds to the distance between the reachable range and the robot. The distance estimation unit102transmits the obtained distance d to the interference probability calculation unit103.

The interference probability calculation unit103calculates an interference probability between the robot200and the operator400by using the distance d. In the present embodiment, an interference probability depends on the overlap condition between the reachable range of an operator and the arm of the robot200, and an interference probability is calculated as follows.

The interference probability calculation unit103obtains 0% as the interference probability, in the case where the distance d between the circular reachable range determined by the physical characteristics of the operator400and the arm of the robot200is larger than a threshold Th. The interference probability calculation unit103obtains 50% as the interference probability, in the case where the distance d is smaller than the threshold Th and larger than 0. The interference probability calculation unit103obtains 100% as the interference probability, in the case where the distance d is 0 or less (overlapped condition). The interference probability calculation unit103transmits the resultant interference probability to the operation control unit104.

The operation control unit104controls the operation of the arm and the end effector of the robot200on the basis of a control program. In the case where the interference probability is 0%, the operation control unit104controls the arm of the robot200to operate at the speed (normal speed) set by the control program. In the case where the interference probability is 100%, the operation control unit104controls the arm of the robot200to stop. In the case where the interference probability is 50%, the operation control unit104controls the arm of the robot200to operate at a speed of, for example, approximately 20% to the normal speed in the present embodiment, the interference probability is divided into three levels. Alternatively, in the case where the distance d is smaller than the threshold Th and larger than 0, the interference probability may be divided into a plurality of levels of, for example, 10%, 30%, 50% and 70%, depending on the value of the distance d. The speed of the arm is controlled stepwise on the basis of the value of the interference probability.

It is noted that, in the case where the interference probability between the robot200and the operator400is 100%, the operation control unit104preferably controls the arm of the robot200to move to the position where the interference probability is 50% or less and to stop at the position, and controls the arm of the robot200to return to the original position after the interference with the operator is avoided.

The operation control unit104controls the speed of the arm depending on the direction of the arm to be controlled to move by the control program. In an example, in the case where the interference probability is 100%, the operation control unit104controls the arm of the robot200to stop during when the arm is approaching the operator400, while the operation control unit104controls the arm of the robot200to operate at the normal speed during when the arm is moving away from the operator400. The moving direction of the arm of the robot200is able to be obtained on the basis of the control program, or alternatively may be obtained by obtaining the change of the distance d and then determining whether the distance d is increasing or decreasing.

The operation of the above-described robot control device100is described by referring to the flowchart ofFIG. 4. The description below is made, assuming that the arm of the robot200moves to approach the operator400. In step S11, the information acquisition unit101acquires the image data including the QR code (registered trademark)210and the QR code420from the camera300. In step S12, the distance estimation unit102obtains the distance d between the robot200and the reachable range of the operator400by using the image data. In step S13, the interference probability calculation unit103obtains an interference probability on the basis of the distance d. Then in step S14, the value of the interference probability is determined. In the case where the interference probability is 0%, then in step S15, the operation control unit104controls the robot200to operate at the normal speed. In the case where the interference probability is 50%, then in step S16, the operation control unit104controls the robot200to operate at a speed of approximately 20% to the normal speed. In the case where the interference probability is 100%, then in step S17, the operation control unit104controls the robot200to stop. In step S18, the operation control unit104determines whether to finish the control program. In the case where the control program is not to be finished, the processing returns to step S11. In the case where the control program is to be finished, the operation control unit104finishes the processing.

The above-described operation by the robot control device100enables to prevent the interference between the operator400and the robot200from occurring. That is, the operation by the robot control device100enables to prevent the arm of the robot200from intruding on the work table501during when the operator400is operating on the work table501. The description above is about the example of preventing the interference between the operator400and the robot200. The same applies to the case where a person other than the operator400, for example, a manager wearing a working cap with the QR code attached to the head top approaches the robot200.

The functional blocks included in the robot control device100and the operation thereof have been described so far. In order to realize the functional blocks of the robot control device100, the robot control device100includes an arithmetic processing unit such as a CPU (central processing unit). The robot control device100further includes an auxiliary storage device such as an HDD (hard disk drive) storing various types of control programs such as application software and OS (operating system), and a main storage device such as a RAM (random access memory) configured to store data temporarily required when the arithmetic processing unit executes a program.

Then, in the robot control device100, the arithmetic processing unit reads such application software and OS from the auxiliary storage device, expands the read application software and the OS in the main storage device, and executes arithmetic processing on the basis of the application software and the OS. On the basis of the arithmetic result, various types of hardware included in respective devices are controlled. As a result, the functional blocks or the present embodiment are realized. That is, the present embodiment is realized by cooperation of hardware and software.

<Example of Work Process>

An example of the work process by use of the robot control system10is described below by referring toFIG. 5. The robot200carries a workpiece-in-process601placed on a work table502onto the work table501by using the arm, and then moves the arm toward the work table502in order to carry a next workpiece-in-process602placed on the work table502. At this time, it is assumed that the operator400faces a work table503, not being positioned in the vicinity of the work table501. The operator400moves from the work table503to the work table501, attaches two parts to the workpiece-in-process601placed on the work table501, and carries the workpiece-in-process601to the next work table503. The operator400then inspects the workpiece-in-process601with the two parts attached, on the work table503by using an inspection device. During when the operator400is inspecting the workpiece-in-process601on the work table503, the robot200carries the workpiece-in-process602placed on the work table502onto the work table501by using the arm.

In the above-described work process, the operator400is not positioned in the vicinity of the work table501during when the robot200carries the workpiece-in-process601onto the work table501, and thus the interference probability between the robot200and the operator400is 0%. When the robot200carries the workpiece-in-process601onto the work table501by the arm, and thereafter moves the arm toward the work table502, the interference probability becomes 0% even when the operator400is positioned in the vicinity of the work table501.

However, when the robot200is about to carry the workpiece-in-process602placed on the work table502onto the work table501by using the arm, and if the operator400is in the step of attaching the two parts to the workpiece-in-process601on the work table501, the interference between the operator400and the robot200may occur.

When the interference probability becomes 50%, the robot control device100reduces the speed of the arm of the robot200to 20% to the normal speed when the distance d becomes 0 and when the interference probability becomes 100% or before the interference probability becomes 100%, the robot control device100prevents the interference by controlling the arm of the robot200to stop. Thereafter, when the operator400moves to carry the workpiece-in-process601(product) with the two parts attached onto the work table503, the robot control device100controls the robot200to carry the workpiece-in-process602onto the work table501after the interference probability becomes 0%.

As described above, the robot control device100according to the present embodiment controls the robot200by calculating the interference probability between the robot200and the operator400in order to avoid the interference between the robot200and the operator400.

It noted that the robot control device described above is realized by hardware, software, or the combination thereof. A robot control method to be executed by the cooperation of respective devices included in the robot control system described above is also realized by hardware, software, or the combination thereof. The above expression of “being realized by software” means being realized when a computer reads and executes a program.

A program is able to be stored by various types of non-transitory computer readable media, and is able to be supplied to a computer. The non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disk and hard disk drive), magneto-optical recording media (for example, magneto-optical disk), CD-ROM (read only memory), CD-R, CD-R/W, semiconductor memory (for example, mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, and RAM (random access memory). A program may also be supplied to a computer by various types of transitory computer readable media. Although the above-described embodiment is a preferred embodiment of the present invention, the scope of the present invention is not limited only to the above-described embodiment. Various modifications are available without departing from the gist of the present invention. For example, modifications with the following changes are available.

In the embodiment described above, the robot control device100controls the operation of the robot200, on the basis of the image data including the QR code (registered trademark)210and the QR code420captured by the camera300. The QR code420includes information such as an operator ID and physical characteristics of the operator, and the QR code210includes information such as a robot ID and a robot size. As a modification, the QR code420may include only an operator ID, and the QR code210may include only a robot ID. In this case, the distance estimation unit102previously stores information such as physical characteristics of an operator in association with an operator ID, and previously stores information such as a robot size in association with a robot ID. With this manner, the distance estimation unit102is able to obtain the distance d.

In the above-described embodiment, it is assumed that the robot control device100and the robot200are realized in individual devices. As a modification, the robot control device100and the robot200may be realized in one device. Alternatively, some or the all of the functional blocks of the robot control device100may be realized in the same device as the robot200.

In the above-described embodiment, it is assumed that the robot200and the operator400are under a one-to-one relation. As a modification, the present embodiment may be applied to the case where the robot200and the operator400are under a one-to-multiple relation, a multiple-to-one relation, or a multiple-to-multiple relation.

EXPLANATION OF REFERENCE NUMERALS