ROBOT CONTROL DEVICE, ROBOT SYSTEM, AND ROBOT CONTROL METHOD

Abstract

Robot control device (20) for controlling a robot (10), wherein the robot control device (20) has a receiving unit (21) which receives transmission data containing operating commands for the robot (10) via wireless communication; a delay detection unit (22) which detects the delay of the received transmission data from the scheduled arrival time; and a speed setting unit (23) which sets the operating speed at which the robot (10) is operated according to the operating commands to a second speed, which is lower than a first speed set when a deceleration is not detected, and greater than zero, when a deceleration is detected.

Description

[0001] The present invention relates to a robot control device, a robot system, and a robot control method.

[0002] In recent years, robot systems have been proposed in which an operation input device for providing operation inputs to the robot and a robot control device are wirelessly connected. Patent Application Publication JP 2015-020215 A describes a robot control system in which a handheld guide device serving as an operation input device is wirelessly connected to a control device and a monitoring device. Other robot control systems and methods are known, for example, from DE 10 2015 002 192 B4, DE 10 2014 104 377 A1, WO 2019 / 052 665 A1, US 2019 / 0 061 155 A1, US 2016 / 0 109 883 A1, and JP 2018-107 568 A.

[0003] In wireless communication, the communication status may deteriorate due to environmental influences. When the wireless communication status deteriorates in a robot system such as the one described above, in which the operation input device and the robot controller are wirelessly connected, the transmission data from the operation input device may be delayed and not reach the robot controller at a specified time. In such a case, the robot controller generally takes action to stop the robot. However, stopping the robot during a teaching activity will result in a decrease in the efficiency of the teaching activity as a whole.

[0004] It is therefore an object of the present invention to provide an improved robot control device. A further object of the present invention is to provide a robot system and a robot control method.

[0005] This object is achieved according to the invention by a robot control system according to claim 1. With regard to the robot system, the object is achieved by the subject matter of claim 4 and with regard to the robot control method by the subject matter of claim 6.

[0006] Specifically, the object is achieved according to the invention by a robot control device for controlling a robot, comprising a receiving unit configured to receive, by wireless communication, transmission data containing an operation command for the robot; a delay detection unit configured to detect a delay of the received transmission data from a scheduled arrival time; and a speed setting unit configured to set a movement speed of the robot, which is moved according to the operation commands, to a second speed, which is lower than a first speed, which is set when the delay is not detected, and greater than zero, upon detection of the delay.

[0007] The objects, features and advantages of the present invention will become more apparent from the following explanation of an embodiment taken in conjunction with the accompanying drawings. In the accompanying drawings is Fig. 1 is a view illustrating the entire structure of a robot system including a robot control device according to an embodiment; is Fig. 2 is a functional block diagram of the robot control device; is Fig. 3 is a view showing a first example of the operation for detecting a delay of the transmission data by the delay detecting unit; is Fig. 4 is a view showing a second example of the operation for detecting a delay of the transmission data by the delay detecting unit; is Fig. 5 is a view schematically illustrating the positional relationship between a robot and an operator in a horizontal plane; is Fig. 6 is a diagram showing an example of the change in the speed of the robot (a specific moving part) due to a speed setting by the speed setting unit; is Fig. 7 is a flowchart illustrating the robot control method with respect to the operating speed; and is Fig. 8 is a view showing the entire structure of the robot system when the operation input device is a teaching operation panel.

[0008] An embodiment of the present disclosure will be explained below with reference to the accompanying drawings. Throughout the drawings, corresponding structural elements are designated by common reference numerals. For convenience of explanation, the scale of these drawings has been arbitrarily changed. The embodiment shown in the drawings is an example of the embodiment of the present invention, but the present invention is not limited to the embodiment shown in the drawings.

[0009] Fig. 1 is a view illustrating the entire structure of a robot system 100 including a robot control device 20 according to an embodiment. Fig. 2 is a functional block diagram of the robot control device 20. As in Fig. As shown in Figure 1, the robot system 100 includes a robot 10, the robot controller 20 that controls the robot 10, and a handheld device 30 as an operation input device for operating the robot 10. In the present embodiment, the robot 10 is a vertically articulated robot having a base portion 11 fixed to a facility floor and an arm portion 12 composed of a plurality of joint portions and link members. A robot of another type may also be used as the robot 10. The handheld device 30 is attached to a specific movable part of the robot 10 (in the present embodiment, to the tip end of the arm).

[0010] The handheld device 30 includes an operating unit 31 having an operating lever 31a, an emergency stop switch (not shown), and so on, and a transmitting unit 32 that transmits transmission data containing operation commands input via the operating unit 31 through wireless communication. The robot controller 20 operates the robot 10 according to the operation commands received from the handheld device 30 through wireless communication. The wireless communication between the handheld device 30 and the robot controller 20 may also be based on a specific wireless communication standard such as wireless LAN. The robot controller 20 may also be configured as a general computer including a CPU, a ROM, a RAM, a storage device, an operating unit, a network interface, and so on.

[0011] An operator (not shown) performs a teaching operation by operating the robot 10 using the handheld teaching device 30. For example, the operator moves a specific movable part of the robot 10 (the tip end of the arm in the present embodiment) in a desired direction by tilting the operation lever 31a. In a system using wireless communication, such as the robot system 100, the communication state may deteriorate due to environmental influences. When the communication state has deteriorated, the transmission data from the handheld teaching device 30 may be delayed and may not be received by the robot control device 20 at a specified time.The robot control device 20 is designed to appropriately control the speed of the robot 10 when such a situation occurs, with a view to suppressing a decrease in the efficiency of the teaching work as a whole while also ensuring safety.

[0012] As in Fig. 2, the robot control device 20 includes a receiving unit 21, a delay detection unit 22, and a speed setting unit 23. The receiving unit 21 receives transmission data containing operation commands from the handheld device 30 through wireless communication. The delay detection unit 22 detects a delay of the transmission data from the scheduled arrival time. When a delay in the arrival of the transmission data has been detected by the delay detection unit 22, the speed setting unit 23 sets the operating speed when operating the robot 10 according to the operation commands to a second speed that is lower than a first speed, which is set when no delay is detected, and greater than zero. In the structural example shown in Fig. 1, the robot control device 20 is configured to receive the wireless signals from the handheld device 30 directly, but the robot control device 20 may also be configured to receive the transmission signals from the handheld device 30 via an externally connected device with wireless communication capability, such as a teaching control panel.

[0013] Fig. 3 is a view showing a first example of the operation for detecting a delay in the transmission data by the delay detection unit 22. Generally, the hand-held device 30 continuously transmits operation commands (for example, a command to move in the positive X-axis direction of a robot coordinate system) at a certain period while the operation lever 31a is tilted in a desired direction by the operator. Fig. 3 shows the timing at which the transmitting unit 32 continuously transmits the transmission data periodically while the tilting operation of the operating lever 31a is performed. Here, it is assumed that an identifier (1, 2, 3, 4, ... n) indicating the order of transmission is added to each transmission data. The case is assumed that the period of the transmission data is known in the robot control device 20. At the bottom of Fig. 3 shows the timing at which the receiving unit 21 receives the transmission data (1, 2, 3, 4, ... n). In this case, the delay detection unit 22 determines the scheduled arrival time for the arrival of the second and subsequent transmission data by counting an internal clock signal with the time of reception of the first transmission data as a trigger, and observes whether the respective transmission data has been delayed from the scheduled arrival time. For example, it is assumed that the nth transmission data arrived late by a time τ from the scheduled arrival time t0. In this case, the delay detection unit 22 detects that a delay of a time τ has occurred in the nth transmission data.

[0014] Fig. 4 is a view showing a second example of the operation for detecting a delay of the transmission data by the delay detecting unit 22. In the second example, the transmitting unit 32 of the handheld device 30 performs transmission by adding the transmission timing to the transmission data. In the case of this second example, the timings of the respective internal clocks between the handheld device 30 and the robot control device 20 are coordinated in advance, for example, using a timing synchronization function via a network. It is assumed that the transmitting unit 32 of the handheld device 30 transmits the transmission data (DATA1) as shown in Fig. 4 with the addition of the transmission time Ta1. When the receiving unit 21 in the robot control unit 20 receives the transmission data (DATA1), the delay detection unit 22 detects, by referring to the time of the internal clock, that the transmission data (DATA1) arrived after a time τ1 from the transmission time Ta1. As an example, the delay detection unit 22 sets a time at which a transmission delay time normally required for the transmission of wireless signals has been added to the transmission time Ta1 as the scheduled arrival time for the transmission data (DATA1). If the arrival time of the transmission data (DATA1) is later than the scheduled arrival time, the delay detection unit 22 detects that a delay has occurred in the transmission data (DATA1). In this case, the delay time of the transmission data (DATA1) can be determined by τ1 - (transmission delay time).

[0015] When the delay detection unit 22 is detected by the Fig. 3 or Fig. 4, the speed setting unit 23 sets the operating speed when moving the robot 10 in the direction specified by the operating commands to a second speed that is lower than a first speed set when no deceleration is detected and greater than zero. The first speed and second speed mentioned here may also be a target speed when controlling the speed of the robot 10 or may be set as a maximum operating speed. The value to which the second speed is set may be set in the following example.

[0016] Setting example 1: a sufficiently slow specific speed to ensure safety even if the robot (the specific moving part) comes into contact with a person.

[0017] Setting Example 2: A speed at which the specific moving part of the robot can stop, when decelerating from the second speed at a specific deceleration rate, within a first specific distance from the position where the specific moving part started decelerating at the specific deceleration rate. The first specific distance in this case is, for example, a distance that can be generally assumed to be maintained between the handheld device 30 and the operator when the operator operates the robot 10 while holding the handheld device 30 (for example, 30 cm). By setting the second speed to such a value, situations such as the robot 10 touching the operator can be prevented when the wireless communication condition deteriorates.

[0018] Setting Example 3: A speed at which the specific moving part of the robot can stop, when decelerating from the second speed at a specific deceleration rate, within the range of a second specific distance from a reference position set on the base section 11 as the fixed section of the robot 10. By setting the second speed to such a value, situations such as the specific moving part of the robot 10 deviating from the range of the second specific distance from the reference position can be prevented in the event of a deterioration in the wireless communication condition, and safety can be ensured. In this case, the speed setting unit 23 can also continuously update the second speed based on the current position of the specific moving part of the robot every time a reception delay in the transmission data is detected.

[0019] The second speed setting example 3 can be used when the operation input device is as shown in Fig. 8 as a construction example, a teaching control panel 30A is shown, which is wirelessly connected to the robot control device 20, can be used even more ideally. Fig. The robot system 100A shown in FIG. 8 includes the robot 10, a robot controller 20A that controls the robot 10, and the teaching operation panel 30A wirelessly connected to the robot controller 20A. The teaching operation panel 30A includes an operation unit that has step operation buttons and the like for operating the robot 10, and a transmission unit that wirelessly transmits transmission data containing operation commands input via the operation unit to the robot controller 20A. In the case of such a system configuration, the operator operates the robot 10 using the teaching operation panel 30A from a position a certain distance from the robot 10.

[0020] Fig. 5 is a view schematically illustrating the positional relationship between the robot 10 and the operator OP in a horizontal plane when a system such as the robot system 100A is used. As shown in Fig. As shown in Fig. 5, in the second speed setting example 3 described above, assuming that the operator OP is operating at a position with a distance D1 from a reference position P0 set on the base portion 11 of the robot 10, the second specified distance may be set to a value of at most the distance D1. For example, it is assumed that the specified moving part of the robot 10 moves radially outward with respect to the reference position P0, and the distance between the specified moving part and the outer edge of the second specified distance range is D0. Furthermore, it is assumed that the specified moving part is decelerated at the constant deceleration degree A0. In this case, the speed setting unit 23 may set the second speed to a value of at most (2D0A0) 1 / 2, which is a speed at which it is possible to stop within the distance D0 in the event of deceleration with the deceleration rate A0.

[0021] In addition, the 100A robot system can be used as Fig. 5, the distance sensor 80 may also include a distance sensor 80 that measures the distance between the reference position P0 and the operator OP. The distance sensor 80 is attached to the base portion 11 of the robot 10, as an example, and is also connected to the robot controller 20A, for example, by a cable. The distance sensor 80 provides the measured distance to the operator OP to the robot controller 20A. In this case, even if the position of the operator OP changes, the position of the operator OP can be detected, and the second specified distance can be set. As the distance sensor 80, for example, a laser sensor, a laser scanner, or the like that can acquire three-dimensional point group data of an object located within a specified measurement range can be used.In order to obtain the shortest distance to an object (or a person) in the environment of the robot 10, several distance sensors 80 can also be arranged on the base section 11 of the robot 10.

[0022] Fig. 6 is a diagram showing an example of the change in the speed of the robot 10 (the specific moving part) in connection with the speed setting operation by the speed setting unit 23. In Fig. 6, the horizontal axis shows time and the vertical axis the speed. Here, a situation is assumed in which the operator is at the initial time (time zero) on the time axis of Fig. 6 performs an operation in which he tilts the operating lever 31a by a certain amount in a desired direction, and this state is maintained. Therefore, the hand-held guiding device 30 transmits over the entire time axis of the diagram of Fig. 6 continuously transmits data containing a specific operation command (for example, a command to move in the positive X-axis direction) at a specific period. It is assumed that time T0 on the time axis of Fig. 6 is a time when the wireless communication state is good, time T1 is a time when the wireless communication state is deteriorated, and time T2 is a time when the wireless communication state has returned to a good state. Since no delay in the transmission data occurs during time T0, the robot controller 20 accelerates the robot 10 (the specific moving part) up to the first speed V1 corresponding to the operation command and moves it at the first speed V1.

[0023] Upon entering time T1 at which the wireless communication state is deteriorated, the delay detection unit 22 detects a delay in the transmission data, and the operating speed of the robot 10 (the specific moving part) is set to the second speed V2, which is lower than the first speed V1, by the speed setting unit 23. Since the state in which the transmission data reaches the robot control device 20 with a specific delay time continues during time T1, the speed setting unit 23 continues the operation of setting the second speed V2. Consequently, at time T1, the robot 10 (the specific moving part) gradually decelerates from the speed V1 and continues its movement in the commanded direction at the second speed V2.

[0024] Upon subsequent entry into time T2 at which the communication state has recovered, the delay in the transmission data is no longer detected, and the speed setting unit 23 returns the setting of the operating speed of the robot 10 (the designated moving part) to the first speed V1. As a result, the robot 10 (the designated moving part) accelerates to the first speed V1 and continues its movement in the commanded direction at the first speed V1. When the second speed is set according to Setting Example 3, the robot control device 20 can control the robot 10 (the designated moving part) at the time when the robot 10 (the designated moving part) has approached the edge of the range of the second designated distance, as shown in Fig. 6, the robot 10 (the specified moving range) may also decelerate and stop at the maximum deceleration rate, as shown by the dashed line L, so that the robot 10 (the specified moving range) does not deviate from the second specified distance range. By performing such control, the edge of the second specified distance range can be set as a virtual barrier that takes effect when the wireless communication condition has deteriorated, and the range within which operation of the robot 10 is possible.

[0025] Fig. Fig. 7 is a view showing the above-described robot control method in terms of operating speed as a flowchart. The processing of Fig. 7 is executed under the control of the CPU of the robot control device 20. As in Fig. 7, the robot control device 20 detects upon receipt of transmission data (step S1) by the Fig. 3 or Fig. 4, a delay in the received transmission data is detected (step S2). If a delay in the transmission data from the target arrival time is detected, the robot control device 20 sets the operating speed of the robot 10 (the specific moving part) to the second speed by the method of any one of the setting examples 1 to 3 described above (step S3). If no delay in the transmission data is detected, the robot control device 20 sets the operating speed of the robot (the specific moving part) to the first speed, which is the speed in the normal state. When the operating speed is set, the robot control device 20 operates the robot 10 according to the operation commands and the set operating speed (step S4).

[0026] As explained above, according to the present embodiment, even if the state of wireless communication deteriorates, it becomes possible to suppress a decrease in the efficiency of teaching as a whole while ensuring security.

[0027] In the foregoing, an embodiment of the present disclosure has been explained, but those skilled in the art will understand that various improvements and changes can be made without departing from the scope of the disclosure of the following claims.

[0028] The Fig. 1 and Fig. 8 are exemplary configuration examples of a robot system, the present invention can be applied to various types of robot systems in which the operation input device and the robot control device are connected by wireless communication.

[0029] The program for executing the processing of the robot control method shown in the above-described embodiment ( Fig. 7) can be recorded on various types of computer-readable recording media (for example, a ROM, an EEPROM, a semiconductor memory such as a flash memory, a magnetic recording medium, an optical disk such as a CD-ROM, a DVD-ROM, etc.).

Claims

[1] Robot control device (20) for controlling a robot (10), wherein the robot control device (20) has a receiving unit (21) which receives transmission data containing operating commands for the robot (10) via wireless communication; a delay detection unit (22) which detects the delay of the received transmission data from the scheduled arrival time; and a speed setting unit (23) which sets the operating speed at which the robot (10) is operated according to the operating commands to a second speed, which is lower than a first speed set when a deceleration is not detected, and greater than zero, when a deceleration is detected. [2] The robot control device (20) according to claim 1, wherein the speed setting unit (23) sets the second speed to a speed at which the specific movable part of the robot (10) can stop in the case of deceleration from the second speed with a specific deceleration degree within a first specific distance from the position at which the specific movable part started the deceleration with the specific deceleration degree. [3] The robot control device (20) according to claim 1, wherein the speed setting unit (23) sets the second speed so that the specific movable part of the robot (10) can stop in the case of deceleration from the second speed with a specific deceleration degree within the range of a second specific distance from a reference position set at a fixing portion of the robot. [4] Robot system (100) that is equipped with a robot (10); an operation input device (30) comprising an operation unit (31) for operating the robot (10), and a transmission unit (32) that transmits transmission data containing operation commands input via the operation unit (31) by wireless communication; and a robot control device (20) according to one of claims 1 to 3 is equipped. [5] Robot system (100) according to claim 4, wherein the operation input device (30) is a hand-held guide device (30) carried on a specific movable part of the robot (10). [6] Robot control method for controlling a robot (10), wherein Transmission data containing operating commands for the robot (10) are received by wireless communication; a delay of the received transmission data is detected by a target arrival time; and if a deceleration has been detected, the operating speed when operating the robot (10) according to the operating commands is set to a second speed which is lower than a first speed which is set when a deceleration is not detected and greater than zero.

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