ROBOT SYSTEM

Description

BACKGROUND1. Technical Field

[0001] The present disclosure relates to a robot system.2. Related Art

[0002] JP A-9-272096 (Patent Literature 1) discloses a robot system capable of selecting, as an operation mode of a robot, a cooperation mode used in a state in which a person is present near the robot and an automatic mode used in a state in which a person is absent near the robot. A user of the robot switches the two modes.

[0003] Further, Patent Literature 2 - JP 3 972350 B2 - relates to a safety protection device for a robotic drive device, provided with a servo-amplifier for inputting a order voltage from D / A board built in a robot controller, a servo-motor driven by the current order outputted from the servo-amplifier and a robot whose drive source is the servo-motor. Touch sensors by which the detected resistance values are reduced monotonously in response to the intensity of the load when the robot is contacted with a human being are provided on the arm of the robot and by comparing threshold value voltage changed by the detection resistances of the touch sensors with the order voltage, a safety protection judging part for judging that the motion of the robot is exerted to the safety side is connected to D / A board.

[0004] Finally, US 2018 / 093378 A1 - Patent Literature 3 - describes production system for performing cooperative work by operator and robot including a robot, a robot controller, and a person detection part. The controller includes first speed comparison unit that has the function of activating a power cutoff unit so as to stop an operation of the robot when a current speed exceeds a predetermined reference speed; and an external-force comparison unit that has the function of activating the power cutoff unit so as to stop the operation of the robot when a current force applied to the robot exceeds a predetermined reference force. The controller disables the functions of the first speed comparison unit and the external-force comparison unit while the person detection part detects the absence of the operator in the cooperative operation space.

[0005] However, in the related art described above, since the user switches the modes of the robot, when the robot is set in a mode different from the cooperation mode, an object and the robot are likely to interfere when the object approaches the robot.SUMMARY

[0006] A robot system according to the invention is defined in claim 1.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is an explanatory diagram of a configuration example of a robot system. FIG. 2 is a functional block diagram of a controller. FIG. 3 is a conceptual diagram showing an example of the controller including a plurality of processors. FIG. 4 is a conceptual diagram showing another example of the controller including the plurality of processors. FIG. 5 is a flowchart showing a procedure for controlling a robot using a monitoring section. DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0008] FIG. 1 is an explanatory diagram showing an example of a robot system. The robot system includes a robot 100 and a controller 200. The periphery of a work region of the robot 100 is surrounded by a safety fence CG. A safety door DR through which people can enter and exit is provided in the safety fence CG.

[0009] The robot 100 includes an arm 110 and a base 120. The arm 110 is sequentially coupled by six joints J1 to J6. An end effector 150 is attached to the distal end portion of the arm 110. In this embodiment, a six-axis robot in which the arm 110 includes the six joints J1 to J6 is illustrated. However, a robot including any arm mechanism including one or more joints can be used.

[0010] In this robot system, an object detecting device 310, a light curtain 320, a safety door sensor 330, and a force detecting section 350 are provided as sensors. Detection signals of the sensors are supplied to the controller 200. The object detecting device 310 is equivalent to an "object detecting device" according to the present disclosure. The light curtain 320 and the safety door sensor 330 are equivalent to "another object detecting device" according to the present disclosure. A part or all of the sensors other than the object detecting device 310 can be omitted.

[0011] The object detecting device 310 is a sensor that detects an object such as a person approaching the robot 100. As the object detecting device 310, a proximity sensor capable of measuring a distance from the robot 100 to the object such as a millimeter wave radar or a laser range sensor can be used. The object detecting device 310 may be configured to, when the object approaches a distance equal to or smaller than a predetermined distance threshold, supply an output signal indicating the approach of the object to the controller 200. The object to be detected by the object detecting device 310 is an object other than work that is a work target of the robot 100. The object detecting device 310 may have a configuration in which a plurality of sensor elements are provided around the base 120 to detect approach of objects over the entire range of 360 degrees around the robot 100. A not-shown abnormality sensor for detecting whether an abnormality has occurred in the object detecting device 310 is desirably provided in the object detecting device 310. When an abnormality has occurred in the object detecting device 310, the object detecting device 310 notifies the controller 200 to that effect.

[0012] The light curtain 320 is an optical sensor that detects an object passing through the safety door DR. An object approaching the robot 100 may be detected by setting one or more light curtains 320 around the robot 100.

[0013] The safety door sensor 330 is an opening and closing sensor that detects an opening and closing state of the safety door DR.

[0014] The force detecting section 350 is a sensor that measures an external force applied to the arm 110. The force detecting section 350 is provided at the proximal end of the arm 110, that is, on the base 120 side of the first joint J1. This disposition is desirable because the force detecting section 350 can detect forces applied to all parts of the arm 110. As the force detecting section 350, for example, a six-axis force sensor can be used. However, a sensor that detects forces in fewer directions may be used. Instead of providing the force detecting section 350 on the proximal end side of the first joint J1, force sensors functioning as force detecting sections may be provided in the other one or more joints.

[0015] FIG. 2 is a block diagram showing functions of the controller 200. The controller 200 includes a processor 210, a monitoring section 220, a memory 230, a display device 260, and an input device 270. The display device 260 and the input device 270 are used as operation devices of a user of the robot 100.

[0016] A program command 232 for realizing various functions of the processor 210 and a control program 234 describing work of the robot 100 are stored in the memory 230. The processor 210 executes the program command 232 to thereby realize a function as a robot control section 240 that controls the robot 100.

[0017] The monitoring section 220 has a function of monitoring the periphery of the robot 100 and notifying a result of the monitoring to the processor 210. The monitoring section 220 can be implemented as, for example, a printed board mounted with one or more electronic components. The monitoring section 220 includes an essential sensor port CP1 and optional sensor ports CP2 and CP3. In the present disclosure, the object detecting device 310 is coupled to the essential sensor port CP1. The light curtain 320 and the safety door sensor 330 are respectively coupled to the optional sensor ports CP2 and CP3. The essential sensor port CP1 is an essential coupling section for coupling the object detecting device 310 to the monitoring section 220 and is equivalent to a "first coupling section" according to the present disclosure. The optional sensor ports CP2 and CP3 are coupling sections nonessential for the monitoring section 220 and are equivalent to a "second coupling section" according to the present disclosure. An object detecting device of the same type as the object detecting device 310 coupled to the essential sensor port CP1 may be coupled to one of the optional sensor ports CP2 and CP2. A part or all of the optional sensor ports CP2 and CP3 may be omitted. In FIG. 2, a detection signal of the force detecting section 350 is supplied to the processor 210 not via the monitoring section 220. However, instead, the detection signal may be supplied to the processor 210 via the monitoring section 220.

[0018] As configuration of the controller 200, various configurations can be adopted other than the configuration shown in FIG. 2. For example, the processor 210 and the memory 230 may be deleted from the controller 200 shown in FIG. 1. The processor 210 and the memory 230 may be provided in another device communicably connected to the controller 200. In this case, an entire device obtained by combining the other device and the controller 200 functions as a controller for the robot 100. In another embodiment, the controller 200 may include two or more processors 210. In still another embodiment, the controller 200 may be realized by a plurality of devices communicably connected to one another. In these various embodiments, the controller 200 is configured as a device or a group of devices including one or more processors 210.

[0019] FIG. 3 is a conceptual diagram showing an example in which the controller for the robot is configured by a plurality of processors. In this example, besides the robot 100 and the controller 200 for the robot 100, personal computers 510 and 520 and a cloud service 500 provided via a network environment such as a LAN are drawn. The personal computers 510 and 520 respectively include processors and memories. A processor and a memory can also be used in the cloud service 500. A controller for the robot 100 can be realized using a part or all of the plurality of processors.

[0020] FIG. 4 is a conceptual diagram showing another example in which the controller for the robot is configured by the plurality of processors. The example shown in FIG. 4 is different from the example shown in FIG. 3 in that the controller 200 for the robot 100 is housed in the robot 100. In this example as well, the controller for the robot 100 can be realized using a part or all of the plurality of processors.

[0021] As a control mode of the robot 100 by the robot control section 240, a human cooperation mode and a normal mode explained below can be used. The human cooperation mode is equivalent to a "first mode" according to the present disclosure and the normal mode is equivalent to a "second mode" according to the present disclosure.Human cooperation mode

[0022] In the human cooperation mode, the robot control section 240 controls the robot 100 in a low-speed operation assuming that the robot 100 and an object approaching the robot 100 come into contact with each other. Specifically, in the human cooperation mode, maximum displacement speed of the arm 110 is limited to preset first speed or less. The "maximum displacement speed" means a maximum value of moving speed in any parts of the arm 110 and the end effector 150. Usually, any one of moving speed of the distal end of the arm 110, moving speed of the distal end of the end effector 150, and moving speed of the joints is the maximum displacement speed. The first speed, which is an upper limit value of the maximum displacement speed in the human cooperation mode, is set to, for example, a value in a range of 100 mm / second or more and 500 mm / seconds or less. The human cooperation mode is equivalent to a mode in which the displacement speed of the robot 100 does not exceed the first speed. In the human cooperation mode, the monitoring section 220 executes monitoring of the control of the robot 100 in the low-speed operation in which the maximum displacement speed of the robot 100 is the first speed or less and an instruction for deceleration or stop of the robot 100 at the time when the contact of the robot 100 and the object is detected using the force detecting section 350. The maximum displacement speed of the robot 100 can be calculated from detection signals of not-shown encoders set in the joints J1 to J6 of the arm 110. Presence or absence of the contact of the robot 100 and the object determined using the force detecting section 350 can be determined, for example, according to whether a force detected by the force detecting section 350 exceeds a preset force threshold. The force threshold is set to a value equal to or larger than an upper limit value of a force assumed in advance in the work of the robot 100. In the human cooperation mode, when an unexpected force is detected by the force detecting section 350, it is determined that the object comes into contact with the robot 100. The robot 100 can be decelerated or stopped. Therefore, it is possible to reduce likelihood of occurrence of interference between an object such as a person and the robot 100.Normal mode

[0023] In the normal mode, the robot control section 240 controls the robot 100 in high-speed operation assuming that the robot 100 and an object approaching the robot 100 do not come into contact with each other. In the normal mode, the maximum displacement speed of the arm 110 is limited to second speed, which is higher than the first speed in the human cooperation mode, or less. The second speed, which is an upper limit value of the maximum displacement speed in the normal mode, is set to, for example, a value in a range of 500 mm / second or more and 3000 mm / second or less. The normal mode is equivalent to a mode in which the displacement speed of the robot 100 is the second speed higher than the first speed. In the normal mode, the monitoring section 220 performs monitoring of the control of the robot 100 in the high-speed operation in which the maximum displacement speed of the robot 100 is the second speed or less. In the normal mode, the monitoring section 220 does not need to perform the monitoring of presence or absence of contact of the robot 100 and the object.

[0024] The selection of the human cooperation mode and the normal mode is executed according to the following step-by-step rules. C1) When the object detecting device 310 is not coupled to the essential sensor port CP1: the human cooperation mode is selected. C2) When the object detecting device 310 is coupled to the essential sensor port CP1: C2-1) when an abnormality is absent in the object detecting device 310: C2-1-1) when an object approaches to a distance equal to or smaller than a predetermined distance threshold: the human cooperation mode is selected. C2-1-2) When an object is not approaching the distance equal to or smaller than the predetermined distance threshold: the normal mode is selected. C2-2) When an abnormality is present in the object detecting device 310: the human cooperation mode is selected.

[0025] As shown in FIG. 2, the safety door sensor 330, which is the opening and closing sensor for the safety door DR, is coupled to the optional sensor port CP3. According to the mode selection rules described above, one of the human cooperation mode and the normal mode is selected irrespective of detection results of the sensors coupled to the optional sensor ports CP2 and CP3. Therefore, even when the safety door DR is open, it is possible to control the robot 100 in the human cooperation mode if the object detecting device 310 is coupled to the essential sensor port CP1 and an object is approaching the robot 100. As a result, there is an advantage that it is possible to continue work even when the safety door DR is open and improve productivity.

[0026] FIG. 5 is a flowchart showing a control procedure for the robot 100 conforming to the rules described above. The control procedure is executed from power-on of the controller 200 in step S110 until power-off of the controller 200 in step S160.

[0027] After the start of the controller 200, in step S120, the monitoring section 220 confirms whether the object detecting device 310 is coupled to the essential sensor port CP1. If the object detecting device 310 is not coupled to the essential sensor port CP1, the monitoring section 220 proceeds to step S210 and notifies the robot control section 240 that the object detecting device 310 is not coupled to the essential sensor port CP1. At this time, the monitoring section 220 may display on the display device 260 that the object detecting device 310 is not coupled to the essential sensor port CP1 and notify the user of the robot 100 to that effect. In step S220, the monitoring section 220 instructs the robot control section 240 to operate in the human cooperation mode. In step S230, the monitoring section 220 continues to perform the monitoring of the robot 100 and the robot control section 240 in human cooperation mode monitoring. The "human cooperation mode monitoring" is a monitoring mode suitable for the human cooperation mode and is a monitoring mode assuming a case in which an object such as a person and the robot 100 are likely to come into contact with each other. Specifically, in the human cooperation mode monitoring, monitoring of the control of the robot 100 in the low-speed operation in which the maximum displacement speed of the robot 100 is the first speed or less and monitoring of presence or absence of contact of the arm 110 and the object determined using the force detecting section 350 are performed.

[0028] When the object detecting device 310 is coupled to the essential sensor port CP1 as a result of the confirmation in step S120, the monitoring section 220 proceeds to step S130 and performs abnormality detection for the object detecting device 310 coupled to the essential sensor port CP1. When an abnormality is detected in the object detecting device 310, the monitoring section 220 proceeds to step S135 and notifies the robot control section 240 that the abnormality is detected in the object detecting device 310 coupled to the essential sensor port CP1. At this time, the monitoring section 220 may display on the display device 260 that the abnormality is present in the object detecting device 310 and notify the user of the robot 100 to that effect. After step S135, steps S220 and S230 described above are executed.

[0029] When an abnormality is not detected in the object detecting device 310 as a result of the confirmation in step S130, the monitoring section 220 proceeds to step S140 and confirms, using the object detecting device 310, whether an object approaching the robot 100 is present around the robot 100. The determination of whether an object approaching the robot 100 is present can be executed, for example, according to whether the distance between the robot 100 and the object is the predetermined distance threshold or less. When detecting that an object approaching the robot 100 is present, the monitoring section 220 proceeds to step S310 and notifies the robot control section 240 that the object approaching the robot 100 is detected by the object detecting device 310 coupled to the essential sensor port CP1. At this time, the monitoring section 220 may display on the display device 260 that the object approaching the robot 100 is detected and notify the user of the robot 100 to that effect. In step S320, the monitoring section 220 instructs the robot control section 240 to operate in the human cooperation mode. In step S330, the monitoring section 220 is switched to the human cooperation mode monitoring.

[0030] On the other hand, when detecting in step S140 that an object approaching the robot 100 is absent, the monitoring section 220 proceeds to step S410 and notifies the robot control section 240 that an object approaching the robot 100 is not detected by the object detecting device 310. At this time, the monitoring section 220 may display on the display device 260 that an object approaching the robot 100 is absent and notify the user of the robot 100 to that effect. In step S420, the monitoring section 220 instructs the robot control section 240 to operate in the normal mode. In step S430, the monitoring mode of the monitoring section 220 is switched to normal mode monitoring. The "normal mode monitoring" is a monitoring mode suitable for the normal mode and is a monitoring mode assuming a case in which an object such as a person and the robot 100 are unlikely to come into contact with each other. Specifically, in the normal mode monitoring, monitoring of the control of the robot 100 in the low-speed operation in which the maximum displacement speed of the robot 100 is the first speed or less is perform. However, it is unnecessary to perform monitoring of presence or absence of contact of the arm 110 and the object determined using the force detecting section 350.

[0031] After steps S230, S330, and S430, in step S150, the monitoring section 220 confirms whether power-off of the controller 200 is performed. When the power-off of the controller 200 is not performed, the monitoring section 220 returns to step S130 described above. On the other hand, when the power-off of the controller 200 is performed, the monitoring section 220 ends the procedure shown in FIG. 5 in step S160.

[0032] When the object detecting device 310 is not coupled to the essential sensor port CP1 and the object detecting device 310 or another object detecting device is coupled to one of the optional sensor ports CP2 and CP3, the robot 100 may be controlled in the human cooperation mode. Then, even when the object detecting device 310 is not coupled to the essential sensor port CP1 and some object detecting device is coupled to one of the optional sensor ports CP2 and CP3, the robot 100 is controlled in the human cooperation mode. Therefore, it is possible to more surely reduce the likelihood of occurrence of interference between an object such as a person and the robot 100.

[0033] When approach of an object to the robot 100 is detected using the sensors coupled to the optional sensor ports CP2 and CP3, the mode switching may be executed as explained below. That is, when some object detecting device is coupled to one of the optional sensor ports CP2 and CP3, the monitoring section 220 confirms whether an abnormality is present in the object detecting device coupled to the optional sensor port CP2 or CP3. When an abnormality is present in the object detecting device, the monitoring section 220 notifies the robot control section 240 that the abnormality is detected in the object detecting device coupled to the optional sensor port. The monitoring section 220 instructs the robot control section 240 to operate in the human cooperation mode. At this time, the monitoring section 220 may continue to perform the monitoring of the robot 100 and the robot control section 240 in the human cooperation mode monitoring. On the other hand, when an abnormality is absent in the object detecting device coupled to optional sensor port CP2 or CP3, the human cooperation mode and the normal mode may be switched using a logical sum of a detection result of the object by the object detecting device 310 coupled to the essential sensor port CP1 and a detection result of the object by the other object detecting device coupled to the optional sensor port CP2 or CP3. Then, it is possible to more surely detect an object approaching the robot 100 compared with when only the object detecting device 310 coupled to the essential sensor port CP1 is used. Therefore, it is possible to more surely prevent the contact of the robot 100 and the object.

[0034] As explained above, in the embodiment explained above, when the object detecting device 310 is coupled to the essential sensor port CP1, the robot 100 is controlled in the normal mode when an object such as a person is not approaching the robot 100. Therefore, it is possible to reduce likelihood of deterioration in productivity. On the other hand, when an object such as a person approaches the robot 100, the robot 100 is controlled in the human cooperation mode in which the displacement speed of the robot 100 is lower than the displacement speed in the normal mode. Therefore, it is possible to reduce the likelihood of occurrence of interference between the object and the robot 100. The robot 100 is controlled in the human cooperation mode even when the object detecting device 310 is not coupled to the essential sensor port CP1. Therefore, it is possible to reduce the likelihood of occurrence of interference between the object and the robot 100 even in this case.

[0035] In the embodiment explained above, the robot 100 is controlled in the human cooperation mode when an abnormality occurs in the object detecting device 310. Therefore, as in the case in which the object detecting device 310 is not coupled to the essential sensor port CP1, it is possible to reduce the likelihood of occurrence of interference between the object and the robot 100.

[0036] In the embodiment explained above, the object detecting device 310 detects the distance between the robot 100 and the object. The human cooperation mode and the normal mode are switched based on the distance. Therefore, when the distance between the object and the robot 100 is sufficiently small, it is possible to control the robot 100 in the human cooperation mode in which the displacement speed of the robot 100 is small. It is possible to further reduce the likelihood of occurrence of interference between the object and the robot 100.

[0037] In the embodiment explained above, in the human cooperation mode, the robot 100 is decelerated or stopped based on an output from the force detecting section 350. Therefore, it is possible to decelerate or stop the robot 100 when an unexpected force is detected by the force detecting section 350. It is possible to further reduce the likelihood of occurrence of interference between the object and the robot 100.

Claims

1. A robot system comprising a robot (100) and a controller (200) including a control section configured to control the robot (100), wherein the controller (200) includes a first coupling section (CP1) coupled to an object detecting device (310) which is a sensor configured to detect a distance between the robot (100) and an object such as a person approaching the robot (100) and to supply an output signal indicating the approach of the object when the distance between the robot (100) and the object is a predetermined distance threshold or less, wherein the controller (200) is configured to control the robot (100) in one of a first mode in which displacement speed of the robot (100) does not exceed first speed and a second mode in which the displacement speed is a second speed higher than the first speed, when the object detecting device (310) is coupled to the first coupling section (CP1), switch the first mode and the second mode based on the distance output from the object detecting device (310), and control the robot (100) in the first mode when the object detecting device is not coupled to the first coupling section (CP1).

2. The robot system according to claim 1, wherein, when a signal indicating an abnormality of the object detecting device (310) is input, the controller (200) is configured to control the robot in the first mode.

3. The robot system according to any one of claims 1 to 2, wherein a force detecting section (350) is configured to detect a force is provided in the robot (100), and in the first mode, the control section is configured to reduce the displacement speed or to stop the robot (100) based on an output from the force detecting section (350).

4. The robot system according to any one of claims 1 to 3, wherein the controller (200) further includes a second coupling section (CP2, CP3) coupled to the object detecting device (310) or another object detecting device (320, 330), and when the object detecting device (310) is not coupled to the first coupling section (CP1) and the object detecting device (310) or the other object detecting device (320, 330) is coupled to the second coupling section (CP2, CP3), the controller (200) is configured to control the robot (100) in the first mode.

5. The robot system according to claim 4, wherein the other object detecting device (330) is an opening and closing sensor for a safety door (DR), the object detecting device (310) is coupled to the first coupling section (CP1), and the opening and closing sensor is coupled to the second coupling section (CP2).