Patent Description:
<CIT> (Patent Literature <NUM>) 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.

Further, Patent Literature <NUM> - <CIT> - 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.

Finally, <CIT> - Patent Literature <NUM> - 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.

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.

A robot system according to the invention is defined in claim <NUM>.

<FIG> is an explanatory diagram showing an example of a robot system. The robot system includes a robot <NUM> and a controller <NUM>. The periphery of a work region of the robot <NUM> 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.

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

In this robot system, an object detecting device <NUM>, a light curtain <NUM>, a safety door sensor <NUM>, and a force detecting section <NUM> are provided as sensors. Detection signals of the sensors are supplied to the controller <NUM>. The object detecting device <NUM> is equivalent to an "object detecting device" according to the present disclosure. The light curtain <NUM> and the safety door sensor <NUM> 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 <NUM> can be omitted.

The object detecting device <NUM> is a sensor that detects an object such as a person approaching the robot <NUM>. As the object detecting device <NUM>, a proximity sensor capable of measuring a distance from the robot <NUM> to the object such as a millimeter wave radar or a laser range sensor can be used. The object detecting device <NUM> 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 <NUM>. The object to be detected by the object detecting device <NUM> is an object other than work that is a work target of the robot <NUM>. The object detecting device <NUM> may have a configuration in which a plurality of sensor elements are provided around the base <NUM> to detect approach of objects over the entire range of <NUM> degrees around the robot <NUM>. A not-shown abnormality sensor for detecting whether an abnormality has occurred in the object detecting device <NUM> is desirably provided in the object detecting device <NUM>. When an abnormality has occurred in the object detecting device <NUM>, the object detecting device <NUM> notifies the controller <NUM> to that effect.

The light curtain <NUM> is an optical sensor that detects an object passing through the safety door DR. An object approaching the robot <NUM> may be detected by setting one or more light curtains <NUM> around the robot <NUM>.

The safety door sensor <NUM> is an opening and closing sensor that detects an opening and closing state of the safety door DR.

The force detecting section <NUM> is a sensor that measures an external force applied to the arm <NUM>. The force detecting section <NUM> is provided at the proximal end of the arm <NUM>, that is, on the base <NUM> side of the first joint J1. This disposition is desirable because the force detecting section <NUM> can detect forces applied to all parts of the arm <NUM>. As the force detecting section <NUM>, 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 <NUM> 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.

<FIG> is a block diagram showing functions of the controller <NUM>. The controller <NUM> includes a processor <NUM>, a monitoring section <NUM>, a memory <NUM>, a display device <NUM>, and an input device <NUM>. The display device <NUM> and the input device <NUM> are used as operation devices of a user of the robot <NUM>.

A program command <NUM> for realizing various functions of the processor <NUM> and a control program <NUM> describing work of the robot <NUM> are stored in the memory <NUM>. The processor <NUM> executes the program command <NUM> to thereby realize a function as a robot control section <NUM> that controls the robot <NUM>.

The monitoring section <NUM> has a function of monitoring the periphery of the robot <NUM> and notifying a result of the monitoring to the processor <NUM>. The monitoring section <NUM> can be implemented as, for example, a printed board mounted with one or more electronic components. The monitoring section <NUM> includes an essential sensor port CP1 and optional sensor ports CP2 and CP3. In the present disclosure, the object detecting device <NUM> is coupled to the essential sensor port CP1. The light curtain <NUM> and the safety door sensor <NUM> 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 <NUM> to the monitoring section <NUM> 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 <NUM> 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 <NUM> 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>, a detection signal of the force detecting section <NUM> is supplied to the processor <NUM> not via the monitoring section <NUM>. However, instead, the detection signal may be supplied to the processor <NUM> via the monitoring section <NUM>.

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

<FIG> 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 <NUM> and the controller <NUM> for the robot <NUM>, personal computers <NUM> and <NUM> and a cloud service <NUM> provided via a network environment such as a LAN are drawn. The personal computers <NUM> and <NUM> respectively include processors and memories. A processor and a memory can also be used in the cloud service <NUM>. A controller for the robot <NUM> can be realized using a part or all of the plurality of processors.

<FIG> 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> is different from the example shown in <FIG> in that the controller <NUM> for the robot <NUM> is housed in the robot <NUM>. In this example as well, the controller for the robot <NUM> can be realized using a part or all of the plurality of processors.

As a control mode of the robot <NUM> by the robot control section <NUM>, 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.

In the human cooperation mode, the robot control section <NUM> controls the robot <NUM> in a low-speed operation assuming that the robot <NUM> and an object approaching the robot <NUM> come into contact with each other. Specifically, in the human cooperation mode, maximum displacement speed of the arm <NUM> 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 <NUM> and the end effector <NUM>. Usually, any one of moving speed of the distal end of the arm <NUM>, moving speed of the distal end of the end effector <NUM>, 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 <NUM>/second or more and <NUM>/seconds or less. The human cooperation mode is equivalent to a mode in which the displacement speed of the robot <NUM> does not exceed the first speed. In the human cooperation mode, the monitoring section <NUM> executes monitoring of the control of the robot <NUM> in the low-speed operation in which the maximum displacement speed of the robot <NUM> is the first speed or less and an instruction for deceleration or stop of the robot <NUM> at the time when the contact of the robot <NUM> and the object is detected using the force detecting section <NUM>. The maximum displacement speed of the robot <NUM> can be calculated from detection signals of not-shown encoders set in the joints J1 to J6 of the arm <NUM>. Presence or absence of the contact of the robot <NUM> and the object determined using the force detecting section <NUM> can be determined, for example, according to whether a force detected by the force detecting section <NUM> 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 <NUM>. In the human cooperation mode, when an unexpected force is detected by the force detecting section <NUM>, it is determined that the object comes into contact with the robot <NUM>. The robot <NUM> 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 <NUM>.

In the normal mode, the robot control section <NUM> controls the robot <NUM> in high-speed operation assuming that the robot <NUM> and an object approaching the robot <NUM> do not come into contact with each other. In the normal mode, the maximum displacement speed of the arm <NUM> 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 <NUM>/second or more and <NUM>/second or less. The normal mode is equivalent to a mode in which the displacement speed of the robot <NUM> is the second speed higher than the first speed. In the normal mode, the monitoring section <NUM> performs monitoring of the control of the robot <NUM> in the high-speed operation in which the maximum displacement speed of the robot <NUM> is the second speed or less. In the normal mode, the monitoring section <NUM> does not need to perform the monitoring of presence or absence of contact of the robot <NUM> and the object.

The selection of the human cooperation mode and the normal mode is executed according to the following step-by-step rules.

As shown in <FIG>, the safety door sensor <NUM>, 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 <NUM> in the human cooperation mode if the object detecting device <NUM> is coupled to the essential sensor port CP1 and an object is approaching the robot <NUM>. 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.

<FIG> is a flowchart showing a control procedure for the robot <NUM> conforming to the rules described above. The control procedure is executed from power-on of the controller <NUM> in step S110 until power-off of the controller <NUM> in step S160.

After the start of the controller <NUM>, in step S120, the monitoring section <NUM> confirms whether the object detecting device <NUM> is coupled to the essential sensor port CP1. If the object detecting device <NUM> is not coupled to the essential sensor port CP1, the monitoring section <NUM> proceeds to step S210 and notifies the robot control section <NUM> that the object detecting device <NUM> is not coupled to the essential sensor port CP1. At this time, the monitoring section <NUM> may display on the display device <NUM> that the object detecting device <NUM> is not coupled to the essential sensor port CP1 and notify the user of the robot <NUM> to that effect. In step S220, the monitoring section <NUM> instructs the robot control section <NUM> to operate in the human cooperation mode. In step S230, the monitoring section <NUM> continues to perform the monitoring of the robot <NUM> and the robot control section <NUM> 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 <NUM> are likely to come into contact with each other. Specifically, in the human cooperation mode monitoring, monitoring of the control of the robot <NUM> in the low-speed operation in which the maximum displacement speed of the robot <NUM> is the first speed or less and monitoring of presence or absence of contact of the arm <NUM> and the object determined using the force detecting section <NUM> are performed.

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

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

On the other hand, when detecting in step S140 that an object approaching the robot <NUM> is absent, the monitoring section <NUM> proceeds to step S410 and notifies the robot control section <NUM> that an object approaching the robot <NUM> is not detected by the object detecting device <NUM>. At this time, the monitoring section <NUM> may display on the display device <NUM> that an object approaching the robot <NUM> is absent and notify the user of the robot <NUM> to that effect. In step S420, the monitoring section <NUM> instructs the robot control section <NUM> to operate in the normal mode. In step S430, the monitoring mode of the monitoring section <NUM> 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 <NUM> are unlikely to come into contact with each other. Specifically, in the normal mode monitoring, monitoring of the control of the robot <NUM> in the low-speed operation in which the maximum displacement speed of the robot <NUM> is the first speed or less is perform. However, it is unnecessary to perform monitoring of presence or absence of contact of the arm <NUM> and the object determined using the force detecting section <NUM>.

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

When the object detecting device <NUM> is not coupled to the essential sensor port CP1 and the object detecting device <NUM> or another object detecting device is coupled to one of the optional sensor ports CP2 and CP3, the robot <NUM> may be controlled in the human cooperation mode. Then, even when the object detecting device <NUM> 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 <NUM> 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 <NUM>.

When approach of an object to the robot <NUM> 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 <NUM> 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 <NUM> notifies the robot control section <NUM> that the abnormality is detected in the object detecting device coupled to the optional sensor port. The monitoring section <NUM> instructs the robot control section <NUM> to operate in the human cooperation mode. At this time, the monitoring section <NUM> may continue to perform the monitoring of the robot <NUM> and the robot control section <NUM> 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 <NUM> 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 <NUM> compared with when only the object detecting device <NUM> coupled to the essential sensor port CP1 is used. Therefore, it is possible to more surely prevent the contact of the robot <NUM> and the object.

As explained above, in the embodiment explained above, when the object detecting device <NUM> is coupled to the essential sensor port CP1, the robot <NUM> is controlled in the normal mode when an object such as a person is not approaching the robot <NUM>. 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 <NUM>, the robot <NUM> is controlled in the human cooperation mode in which the displacement speed of the robot <NUM> 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 <NUM>. The robot <NUM> is controlled in the human cooperation mode even when the object detecting device <NUM> 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 <NUM> even in this case.

In the embodiment explained above, the robot <NUM> is controlled in the human cooperation mode when an abnormality occurs in the object detecting device <NUM>. Therefore, as in the case in which the object detecting device <NUM> 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 <NUM>.

In the embodiment explained above, the object detecting device <NUM> detects the distance between the robot <NUM> 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 <NUM> is sufficiently small, it is possible to control the robot <NUM> in the human cooperation mode in which the displacement speed of the robot <NUM> is small. It is possible to further reduce the likelihood of occurrence of interference between the object and the robot <NUM>.

Claim 1:
A robot system comprising a robot (<NUM>) and a controller (<NUM>) including a control section configured to control the robot (<NUM>), wherein
the controller (<NUM>) includes a first coupling section (CP1) coupled to an object detecting device (<NUM>) which is a sensor configured to detect a distance between the robot (<NUM>) and an object such as a person approaching the robot (<NUM>) and to supply an output signal indicating the approach of the object when the distance between the robot (<NUM>) and the object is a predetermined distance threshold or less,
wherein the controller (<NUM>) is configured to
control the robot (<NUM>) in one of a first mode in which displacement speed of the robot (<NUM>) 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 (<NUM>) 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 (<NUM>), and
control the robot (<NUM>) in the first mode when the object detecting device is not coupled to the first coupling section (CP1).