Robot system, control device and control method

Abstract

To provide a robot system, a control device and a control method with which contact between a robot and a work body can be accurately detected by measuring the weight of a workpiece W to be transferred, compared to cases where this configuration is not being employed.SOLUTION: A robot system 1 includes: a robot 10; a hand 11 provided on the robot 10; a sensor 14 for detecting a work body within a prescribed range in the periphery of the robot 10; an input unit 151 for receiving information from the sensor 14; a measuring unit for measuring external force applied to the hand 11 or the robot 10; a controlling unit; and a storage unit. The storage unit stores information of a first area that is located within the detection area of the sensor 14 and that is a cooperation area where the robot 10 and a work body cooperate with each other. Further, in the robot system 1, when the input unit receives sensor information about detection of a work body outside of the first area while the hand is gripping a workpiece, the controlling unit causes the measuring unit to measure the weight of the workpiece.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot system, a control device, and a control method, and more particularly to a robot system that performs workpiece transfer operations. [Background technology]

[0002] Robots that work in collaboration with workers in the same workspace are called collaborative robots. Because collaborative robots work in the same workspace as workers, safety is an important consideration, and they are controlled to stop the robot when they detect contact with a worker. Specifically, for example, they detect the load acting on the robot and determine whether it has come into contact with a worker based on the detection results. Then, they control the robot to stop based on the determination results.

[0003] Patent Document 1 describes a robot system. The robot system includes a robot body, a sensor that detects the magnitude of an external force applied to the robot body, a control unit that controls the robot body, and a reference value storage unit that stores the value of the external force detected by the sensor as a reference external force value in an operating state in which only the robot body's own weight and a load handled by the robot body are acting on the robot body. The robot system also includes a determination unit that determines that an external force other than the robot body's own weight and the load has acted on the robot body when the absolute value of the difference between the value of the external force detected by the sensor and the reference external force value stored in the reference value storage unit is greater than a predetermined threshold value while the robot body is operating.

[0004] Patent Document 2 describes a production system having a robot, a robot control device, and a human detection unit. The control device includes a first speed comparison unit that has a function of activating a power cut-off unit to stop the robot's operation when the robot's current speed exceeds a predetermined reference speed, and an external force comparison unit that has a function of activating the power cut-off unit to stop the robot's operation when the current external force acting on the robot exceeds a predetermined reference force. The control device disables the functions of the first speed comparison unit and the external force comparison unit while the human detection unit detects that no human has entered the collaborative operation area.

[0005] Patent Document 3 describes a safety monitoring device that monitors a robot. The safety monitoring device includes a work parameter switching unit that switches work parameters, an external force estimation unit that uses the work parameters to estimate an external force acting on the robot from the external environment as an external force estimated value, and an external force monitoring unit that stops the robot when the external force estimated value satisfies an external force judgment condition. The safety monitoring device also includes a motion monitoring unit that stops the robot based on whether the robot's position is within a predetermined area, etc., a motion monitoring state switching unit that switches between an invalid command and an valid command for the motion monitoring unit, and an external force judgment condition setting unit that switches the external force judgment condition to an external force judgment condition when a valid command is issued, and switches the external force judgment condition to an external force judgment condition when a valid command is issued. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-69633 [Patent Document 2] Japanese Patent Application Publication No. 2018-51734 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-208834 Summary of the Invention [Problem to be solved by the invention]

[0007] When a collaborative robot transfers a workpiece, it is possible to detect loads acting on the robot from sources other than the workpiece by calculating the load acting on the robot minus the load caused by the workpiece. However, if the weight of the workpiece to be transferred is unknown, it is impossible to distinguish between the workpiece and other loads. Therefore, when a collaborative robot lifts a workpiece to perform a task, the robot system must be able to measure the weight of the workpiece before the worker enters the collaboration area where the collaborative robot can work with the worker and the collaborative robot needs to distinguish between the workpiece and other loads. Furthermore, it is preferable that the detection target for detecting contact includes not only the worker but also equipment such as a forklift. Hereinafter, the worker and this equipment will be collectively referred to as the workpiece. The present invention aims to provide a robot system, a control device, and a control method that can accurately detect contact between a robot and a workpiece by measuring the weight of the workpiece to be transferred, compared to when this configuration is not adopted. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a robot system including a robot, a hand provided on the robot, a sensor that detects a workpiece within a predetermined range around the robot, an input unit that receives information from the sensor, a measurement unit that measures external forces acting on the hand or the robot, a control unit, and a memory unit, wherein the memory unit stores information on a first area that is a collaboration area within the sensor's detection range where the robot and the workpiece collaborate, and the control unit measures the weight of the workpiece when it receives sensor information that the input unit has detected the workpiece outside the first area while the hand is holding the workpiece. In this case, a robot system can be provided that can accurately detect contact between the robot and the workpiece by measuring the weight of the workpiece to be transferred, compared to a case in which this configuration is not adopted.

[0009] Here, for example, when a workpiece is detected while being gripped and moved by a hand, the control unit temporarily stops the movement of the hand and the measurement unit measures the weight of the workpiece, thereby enabling the weight of the workpiece to be measured accurately. In addition, for example, the measurement unit determines the load when the hand is stopped as the weight of the workpiece. In this case, the measurement unit can measure the weight of the workpiece by measuring the load. Furthermore, for example, when the input unit receives sensor information indicating that the working body is detected outside the first area while the workpiece is not being gripped by the hand, the control unit measures the weight of the workpiece when gripping the workpiece. In this case, the weight of the workpiece can be accurately measured at the timing when the workpiece is gripped. Furthermore, for example, the robot may further have a second area set outside the first area, and when a workpiece is detected in the second area, the control unit may temporarily suspend the movement of the hand and the measurement unit may measure the weight of the workpiece. In this case, the weight of the workpiece can be measured when there is a risk of contact between the robot and the workpiece. Furthermore, for example, the control unit determines that the robot and the working object have come into contact when the control unit detects the working object in the first area, which makes it possible to more accurately detect that the robot and the working object have come into contact. Furthermore, for example, a stop area may be provided as an area where the robot will stop when a workpiece is detected. In this case, the robot will stop when the workpiece enters an area where the sensor has difficulty detecting the workpiece, ensuring safety. Furthermore, for example, the stopping area may be set around the workpiece storage area, in which case a more appropriate area can be set as the stopping area. Furthermore, for example, when the control unit detects a load greater than the measured weight of the workpiece, it determines that the robot and the workpiece have come into contact. In this case, it is possible to more easily determine that the robot and the workpiece have come into contact. Furthermore, for example, the sensor may be attached to the tip of an outrigger that projects from the housing of the robot system, which widens the range in which the workpiece can be detected.

[0010] The present invention also provides a control device comprising: a robot, a hand provided on the robot, a measuring device that measures external forces acting on the hand or the robot, an input unit connected to a sensor that detects a workpiece within a predetermined range around the robot and that receives information from the sensor, a control unit, and a memory unit, wherein the memory unit stores information about a first area that is a collaboration area within the sensor's detection range where the robot and the workpiece collaborate, and the control unit causes the measuring device to measure the weight of the workpiece when it receives sensor information that the input unit has detected a worker outside the first area while the hand is gripping the workpiece. In this case, a control device can be provided that can more accurately detect contact between the robot and the workpiece by measuring the weight of the workpiece to be transferred, compared to a case in which this configuration is not adopted.

[0011] Furthermore, the present invention provides a control method performed by a control device having a robot, a hand provided on the robot, a measuring device that measures external forces acting on the hand or the robot, and an input unit that is connected to a sensor that detects a workpiece within a predetermined range around the robot and receives information from the sensor, a control unit, and a memory unit, wherein the memory unit stores information about a first area that is a collaboration area within the sensor's detection range where the robot and the workpiece collaborate, and the control unit causes the measuring device to measure the weight of the workpiece when it receives sensor information that the input unit has detected a worker outside the first area while the hand is gripping the workpiece. In this case, a control method can be provided that can accurately detect contact between the robot and the workpiece by measuring the weight of the workpiece to be transferred, compared to a case where this configuration is not adopted. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a robot system, a control device, and a control method that can accurately detect contact between a robot and a workpiece by measuring the weight of the workpiece to be transferred, compared to when this configuration is not adopted. [Brief explanation of the drawings]

[0013] [Figure 1]1A to 1E are external views of a robot system according to this embodiment. [Figure 2] 10(a) and 10(b) are conceptual diagrams illustrating an area set around a robot. [Figure 3] FIG. 1 is a diagram illustrating a basic method by which a control device detects contact between a robot and a worker. [Figure 4] FIG. 2 is a block diagram showing the functional configuration of a control device. [Figure 5] 4 is a flowchart showing the operation of the control device of the present embodiment. [Figure 6] 5(a) to 5(c) are diagrams illustrating in more detail the processing of S502 to S503 in FIG. [Figure 7] 5. (a) and (b) are diagrams illustrating in more detail the processes of S505 to S507 and S510 to S512 in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Overall explanation of Robot System 1> 1(a) to 1(e) are external views of a robot system 1 according to this embodiment. 1(a) is a top view of the robot system 1, showing the robot system 1 as viewed from above. FIG. 1(b) is a front view of the robot system 1, showing the robot system 1 as viewed from the Ib direction in FIG. 1(a). FIG. 1(c) is a left side view of the robot system 1, showing the robot system 1 as viewed from the Ic direction in FIG. 1(a). FIG. 1(d) is a rear view of the robot system 1, showing the robot system 1 as viewed from the Id direction in FIG. 1(a). FIG. 1(e) is a perspective view of the robot system 1. For convenience, the hand 11 and the arm 12 are omitted from FIGS. 1(a) to 1(d), and are shown in FIG. 1(e).

[0015] The illustrated robot system 1 performs the task of transferring a workpiece. The workpiece is an example of an object that can be grasped by a hand. The workpiece is not particularly limited as long as it can be transferred by the robot system 1, and examples include cardboard boxes containing products, products before packaging, and parts that make up products. Transferring is the task of moving a workpiece from one point to another by the robot system 1.

[0016] The robot system 1 is a collaborative robot, and performs work not alone but together with a worker. Therefore, the worker may enter near the robot system 1. For example, the worker may enter near the robot system 1 in the following cases:

[0017] This applies to cases where a pallet is placed to one side of the robot system 1 and another pallet is placed to the other side, and work is transferred between the two pallets; for example, this applies to tasks such as placing work loaded on a pallet onto a belt conveyor, or conversely, loading work carried by a belt conveyor onto a pallet. Furthermore, when the robot system 1 transfers a workpiece to one of the pallets, a worker replaces the pallet that is not being used for work. Therefore, while the robot system 1 is transporting a workpiece, the worker or forklift that is performing the work may come close to the robot system 1. When other work is performed near the robot system 1, that is, when the robot system 1 is a collaborative robot, no fence is set up around it, and it is possible to install equipment for subsequent processes or perform other work near the robot system 1. In this case, workers or equipment for subsequent processes may come near the robot system 1. Therefore, as will be described in detail later, the robot system 1 is designed to operate safely and efficiently while autonomously grasping its surrounding environment.

[0018] The robot system 1 includes a hand 11, an arm 12, a housing 13, a sensor 14, a control device 15, a display unit 16, outriggers 17, pedals 18, and casters 19. In this embodiment, the hand 11 and the arm 12 constitute a robot 10 of this embodiment.

[0019] The hand 11 grips the workpiece. There are no particular limitations on the method by which the hand 11 grips the workpiece, but it can be a vacuum type, for example. That is, a negative pressure is generated in the hand 11 by an ejector or vacuum pump, and the workpiece is gripped by suction using this negative pressure. Alternatively, for example, a gripper type can be used, in which the workpiece is gripped by pinching it with multiple claws. However, the following explanation will be given for the vacuum type using a vacuum pump.

[0020] The arm 12 is composed of a combination of links and joints, and by operating these, the hand 11 attached to the tip of the arm 12 is moved. The arm 12 has multiple links, and by operating electric motors (not shown) incorporated in these links, the arm 12 is directed to a desired position and direction, thereby moving the hand 11 to a desired position and direction. This makes it possible to transfer a workpiece held by the hand 11. After the transfer, the hand 11 can be returned to a position where it will hold the workpiece again.

[0021] The housing 13 is a support for mounting the hand 11, arm 12, sensor 14, control device 15, display unit 16, outrigger 17, pedals 18, and casters 19. The housing 13 is made of a metal or metal alloy such as aluminum, aluminum alloy, titanium alloy, or stainless steel, and has a cavity therein for storing devices.

[0022] The sensor 14 detects a work object within a predetermined range around the robot 10. The sensor 14 detects a worker around the robot 10. The sensor 14 is, for example, a safety laser scanner. The safety laser scanner detects a worker using a laser. Specifically, the safety laser scanner measures the time it takes for an infrared laser beam emitted from the safety laser scanner to hit the worker (the detected object), reflect, and return to the safety laser scanner. The distance to the worker is calculated based on this time. Furthermore, the location of the worker can be detected by calculating the distance by projecting the infrared laser beam in a fan-shaped pattern with varying angles. However, the sensor 14 is not limited to a safety laser scanner. For example, a pyroelectric sensor can be used that uses the pyroelectric effect to detect infrared rays of a specific wavelength emitted by the worker and detects the worker's entry into a predetermined area. Alternatively, an infrared reflective sensor can be used that includes a light-emitting element such as an infrared emitting diode and a light-receiving element that receives the reflected light when the light emitted from the light-emitting element is reflected by the worker. The sensors 14 in this embodiment consist of three sensors: sensors 14a and 14b attached to the tips of outriggers 17 extending from the housing 13 of the robot system 1, and a sensor 14c attached to the back of the housing 13. In this case, the range in which the worker M can be detected is widened.

[0023] The control device 15 controls the entire robot system 1. The control device 15 is, for example, a control board housed inside the housing 13. The control device 15 performs sequence control to operate the hand 11 and the arm 12 in order to transfer a workpiece. Furthermore, as will be described in detail later, when the control device 15 detects a worker in an area set around the robot 10 based on the detection result by the sensor 14, it measures the weight of the workpiece and determines whether the robot 10 has come into contact with the worker based on the measured weight of the workpiece. In this case, it is possible to more accurately detect whether the robot 10 has come into contact with the worker. As a result, if it is determined that the worker has come into contact with the robot 10, the control device 15 performs control to stop the robot 10.

[0024] The control device 15 is a computer device such as a PLC (Programmable Logic Controller) or a robot controller, and includes a processor such as a CPU (Central Processing Unit) as a calculation means, a main memory as a storage means, and a storage. The processor executes various software such as an OS (operating system) and application programs (application software). The main memory is a storage area for storing various software and data used for executing the software. The storage is a storage area for storing input data for the various software and output data from the various software.

[0025] The display unit 16 displays the operating status of the robot system 1. In addition, by using the display unit 16 as a touch panel, an operator can input settings for the robot system 1.

[0026] The outriggers 17 extend like rods from the housing 13 to prevent the robot system 1 from tipping over due to movement of the hand 11 or the arm 12. In this embodiment, the outriggers 17 consist of an outrigger 17a extending from the right side of the robot system 1 and an outrigger 17b extending from the left side of the robot system 1. The sensor 14a is attached to the tip of the outrigger 17a, and the sensor 14b is attached to the tip of the outrigger 17b.

[0027] When an operator presses the pedal 18 with his / her foot, the casters 19 are lowered and fixed in place. This allows the operator to easily move the robot system 1 using the casters 19. Furthermore, by pressing the pedal 18 again, the casters 19 are raised and the robot system 1 is fixed in place. This allows the robot system 1 to be installed at the location where work will be performed.

[0028] The robot system 1 described above has the following features. (1) The front of the housing 13 is made rounded 13a, eliminating blind spots and providing a structure that takes safety into consideration. That is, when a worker stands facing the display unit 16 and looks forward, for example, the worker sees the rounded portion 13a as being downward, but the rounded portion 13a provides good visibility. Therefore, blind spots are eliminated when the worker stands facing the display unit 16 and moves the robot system 1, thereby improving safety.

[0029] (2) By slanting the ridgeline shape of the housing 13, visibility to both sides of the housing 13 can be ensured, which is a consideration for safety. That is, the upper part of the housing 13 is formed into a tapered shape 13b. As a result, when an operator stands facing the display unit 16 and looks forward, for example, the operator will see the tapered shape 13b as downward, but the tapered shape 13b of the upper part of the housing 13 provides good visibility. Therefore, when an operator stands facing the display unit 16 and moves the robot system 1, visibility to both sides of the housing 13 can be ensured, thereby improving safety.

[0030] (3) A wide trajectory can be secured from the placement center of the arm 12. That is, the arm 12 is attached to the attachment portion 13c of the housing 13, and the attachment portion 13c is provided at a position at or near the center of the R-shape 13a. This allows the arm 12 to rotate along the R-shape 13a, increasing the degree of freedom of the trajectory. That is, the range of rotational motion when transferring a workpiece is widened. Therefore, when the robot system 1 transports a workpiece, it is possible to adopt an arm trajectory with a shorter travel distance and smaller changes in acceleration.

[0031] (4) By forming the front of the housing 13 into the rounded shape 13a, storage spaces 13d1 and 13d2 for the sensors 14a and 14b can be provided. As described above, the sensors 14a and 14b are attached to the tips of the outriggers 17a and 17b. The outriggers 17a and 17b can be stored in two stages. When fully stored, the sensor 14a is located in the storage space 13d1, and the sensor 14b is located in the storage space 13d2. As a result, even when the robot system 1 is moved using the casters 19, the sensors 14a and 14b are stored in the storage spaces 13d1 and 13d2, and do not protrude outside. This prevents the sensors 14a and 14b from colliding with each other when the robot system 1 is moved.

[0032] The outriggers 17a, 17b have a mechanism that allows them to be stored in two stages, so that two stages can be set as the placement positions when the sensors 14a, 14b detect a worker: when the outriggers 17a, 17b are extended and when they are stored in one stage. This can be selected depending on the condition of the work space where the robot system 1 is installed, and the installation work of the robot system 1 can be performed efficiently.

[0033] <Explanation of the area set around the robot 10> As described above, the control device 15 detects a worker in the area set around the robot 10. 2(a) and 2(b) are conceptual diagrams illustrating the area set around the robot 10. FIG. As shown in the figure, the areas include area A1, which is set near the robot 10, and area A2, which is set outside area A1 based on the position of the robot 10. In this case, area A1 is an example of a first area, and area A2 is an example of a second area. In this example, the workpiece W is stacked on a pallet P. The robot system 1 then grasps the workpiece W stacked on the pallet P and transfers it to the conveyor Co. As for the movement path at this time, the robot system 1 grasps the workpiece W on the pallet P, and then lifts it vertically to waypoint 1. The robot system 1 then moves the workpiece W horizontally to waypoint 2. The robot system 1 then lowers the workpiece W vertically and places it on the conveyor Co.

[0034] The sensor 14 (sensors 14a to 14c) has a detection range set within a predetermined range around the robot 10, including areas A1 and A2. Here, the predetermined range is, for example, a range obtained by adding a safety distance to the robot's movement range, but it is not limited to this and can be set arbitrarily. The safety distance may be calculated using a formula defined by ISO 13855 or JIS B9715. A portion of the detection range may be excluded from the detection range, or the sensor may be set to not include a specific area. For example, in FIG. 2(b), pallet P may be inappropriate as a detection area because it contains workpieces W. In this case, the detection range of sensor 14a may be set to 270° from the outrigger 17a so that the pallet P is not included in the detection range. The sensor 14 (sensors 14a to 14c) can detect whether worker M is in area A1 or area A2. Furthermore, sensor 14 can detect whether worker M is in either area A1 or area A2. When the worker M enters the area A1, the control device 15 detects whether or not the robot 10 and the worker M have come into contact with each other.

[0035] In this case, area A1 is a collaboration area where the robot 10 and the worker M collaborate. Collaboration between the robot 10 and the worker M allows the workpiece W to be transferred more efficiently. Because there is a possibility that the worker M may come into contact with the robot 10, the control device 15 operates the robot 10 at a slower speed than usual. Therefore, area A1 can also be referred to as a low-speed collaboration area. Because area A1 is a collaboration area where the robot 10 and the worker M collaborate, it is set to encompass the vicinity of the robot 10, targeting an area where the robot 10 and the worker M may come into contact. The area where the robot 10 and the worker M may come into contact preferably includes at least the range physically reachable by the components of the robot 10, for example, the range determined by the rotational range of the links of the arm 12. Area A1 may be set to exclude from the detection range areas around the robot 10 where existing structures exist or areas where it is known in advance that the worker M will not enter. Area A1 may also be set to include multiple discontinuous areas.

[0036] Furthermore, in area A2, the robot 10 and worker M do not cooperate. However, when worker M is detected in area A2, there is a possibility that worker M may enter area A1. Therefore, the control device 15 may operate the robot 10 at a slower speed than usual. In other words, area A2 can also be called a low-speed non-cooperation area. Area A2 is an area for detecting worker M entering area A1, which is a cooperation area, and is set within the detection range of the sensor 14 so as to surround the outside of area A1 based on the robot 10. Note that area A2 may be set so as to exclude from its detection range areas existing buildings around the robot 10 or areas known in advance that worker M will not enter. Furthermore, the second area can be set anywhere as long as it can detect worker M entering area A1. For example, if multiple discontinuous areas are set as area A1, area A2 may be set around each area A1. When the worker M is outside the area A2, the control device 15 operates the robot 10 at a normal speed. In other words, the area outside the area A2 can also be said to be a high-speed non-cooperative area.

[0037] Furthermore, a stop area can be provided inside area A1 as an area where the robot 10 stops when a worker M is detected. In this case, safety can be ensured by stopping the robot 10 when the workpiece enters an area where the sensor 14 has difficulty detecting the worker M. Since the position of the pallet P is loaded with workpieces W, the sensor 14 may not be able to properly detect the worker M, and therefore the area around the pallet P is set as the stop area. In this case, a more appropriate area can be set as the stop area. Note that, because the worker M will have to enter the stop area when replacing the pallet P, the setting of the stop area can be disabled.

[0038] <Explanation of Control by the Control Device 15> FIG. 3 is a diagram showing a basic method by which the control device 15 detects contact between the robot 10 and the worker M. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the load acting on the robot 10. The load acting on the robot 10 can be measured by installing a measuring device that measures the external force acting on the hand 11 or the robot 10. The measuring device is, for example, a force sensor. The force sensor may be provided in the robot 10 in advance, or may be installed later. When worker M is detected in area A1, if the load acting on the robot 10 is F, the control device 15 determines that the robot 10 and worker M are not in contact. This load is the weight of the workpiece W. On the other hand, for example, as shown by line L, if the load acting on the robot 10 exceeds F, the control device 15 determines that the robot 10 and worker M are in contact. In other words, a load greater than the weight of the workpiece W is acting on the robot 10, and this is assumed to be caused by contact between the robot 10 and worker M. On the other hand, if the load acting on the robot 10 is F, the control device 15 determines that the robot 10 and worker M are not in contact. Note that load F can also be considered a threshold for determining that the robot 10 and worker M are in contact. In this case, it is easier to determine that the robot and the workpiece are in contact.

[0039] However, when the workpiece W is being transferred, the load acting on the robot 10 changes. For example, when the workpiece W is moved while being accelerated, the load acting on the robot 10 becomes larger than the weight of the workpiece W. Also, there are times when the weight of the workpiece W is not known in advance. In this case, the load F, which is the threshold value, becomes uncertain. Therefore, in this embodiment, the control device 15 is configured as follows to detect contact between the robot 10 and the worker M.

[0040] FIG. 4 is a block diagram showing the functional configuration of the control device 15. 4, only the functional configuration related to this embodiment is selected from the various functions of the control device 15 and illustrated. As shown in the figure, the control device 15 includes an input unit 151, a measurement unit 152, a control unit 153, and a storage unit 154.

[0041] The input unit 151 receives information from the sensor 14. That is, the input unit 151 acquires the detection result from the sensor 14 that detects the worker M around the robot 10 that is performing the task of transferring the workpiece W. The measuring unit 152 measures the external force acting on the hand 11 or the robot 10. Specifically, when the measuring unit 152 detects the worker M in an area set around the robot 10 (in this case, areas A1 and A2 in FIG. 2) based on the detection result by the sensor 14, the measuring unit 152 measures the weight of the workpiece W in response to a control command from the control unit 153. Note that the measuring unit 152 may be provided as a function of the control device 15, or a measuring device equipped with the measuring unit 152 may be connected to the control device 15 and its function may be executed under control from the control device. The control unit 153 controls the robot 10. That is, the control unit 153 controls the hand 11 and the arm 12 to transfer the workpiece W. The control unit 153 also determines whether the robot 10 has come into contact with the worker M based on the measured weight of the workpiece W. The storage unit 154 stores information about the range of the area set around the robot 10 (in this case, area A1 and area A2).

[0042] FIG. 5 is a flowchart showing the operation of the control device 15 of this embodiment. The operation of the control device 15 will be described below mainly with reference to Figures 4 and 5. Here, a case will be described in which the control device 15 measures the weight of the workpiece W when picking the workpiece W at the pick position (in this case, on the pallet P) and placing it at the place position (in this case, on the conveyor Co). First, the control unit 153 issues a control instruction to pick up the workpiece W (S501). Next, the input unit 151 acquires the detection result from the sensor 14. Then, the control unit 153 determines whether or not the worker M has been detected in area A1 or area A2 before picking up the workpiece W based on the detection result (S502). This can be determined by the control unit 153 acquiring the information on the ranges of area A1 and area A2 stored in the memory unit 154 and comparing it with the detection result. As a result, if it is detected (Yes in S502), the control unit 153 issues a control instruction to the measuring unit 152, which measures the weight of the workpiece W at the pick position (S503). Then, the control unit 153 performs control to move to waypoint 1 (S504). After that, the process proceeds to S509.

[0043] On the other hand, if no workpiece W is detected in S502 (No in S502), the control unit 153 issues a control instruction to move to waypoint 1 (S504). That is, here, the robot system 1 is in a state where the workpiece W is being transported. Next, the input unit 151 acquires the detection result from the sensor 14. Then, the control unit 153 determines, based on the detection result, whether or not worker M has been detected in area A2 before arriving at waypoint 1 (S505). As a result, if it is detected (Yes in S505), the control unit 153 temporarily suspends the operation of the robot 10 (S506). Furthermore, in response to a control instruction from the control unit 153, the measurement unit 152 measures the weight of the workpiece W (S507). Then, the control unit 153 issues a control instruction to move to waypoint 2 (S509). After that, the process proceeds to S514.

[0044] On the other hand, if no detection has been made in S505 (No in S505), the control unit 153 determines whether or not the waypoint 1 has been reached (S508). As a result, if waypoint 1 has been reached (Yes in S508), the control unit 153 issues a control instruction to move to waypoint 2 (S509). If waypoint 1 has not been reached (No in S508), the process returns to S505. Next, the input unit 151 acquires the detection result from the sensor 14. Then, the control unit 153 determines, based on the detection result, whether or not worker M has been detected in area A2 before arriving at waypoint 2 (S510). As a result, if it is detected (Yes in S510), the control unit 153 temporarily suspends the operation of the robot 10 (S511). Furthermore, in response to a control instruction from the control unit 153, the measurement unit 152 measures the weight of the workpiece W (S512). Then, the control unit 153 issues a control instruction to move to the place point (S514).

[0045] On the other hand, if no detection has been made in S510 (No in S510), the control unit 153 determines whether or not the waypoint 2 has been reached (S513). As a result, if waypoint 2 has been reached (Yes in S513), the control unit 153 issues a control instruction to move to the place point (S514). Note that if waypoint 2 has not been reached (No in S513), the process returns to S510. Then, the control unit 153 issues a control instruction to place the work W at the placement point (S515). Furthermore, the control unit 153 determines whether or not all of the works W have been transferred (S516). As a result, if all the works W have been transferred (Yes in S516), the series of processes ends. On the other hand, if all the workpieces W have not been transferred (No in S516), the process returns to S501 and another workpiece W is transferred.

[0046] 6(a) to 6(c) are diagrams illustrating the processing of S502 to S503 in FIG. 5 in more detail. FIG. 6(a) shows a case where worker M is in area A1 when workpiece W is picked up. As explained in S503 of FIG. 5, when the control unit 153 detects worker M in area A1 or area A2 when picking the workpiece W, it measures the weight of the workpiece W at the pick position. Therefore, in the case of FIG. 6(a), the weight of the workpiece W is measured at the pick position. This can also be said to mean that when the input unit 151 receives sensor information indicating that worker M has been detected outside area A1 while the workpiece W is not being grasped by the hand 11, the control unit 153 measures the weight of the workpiece W when the workpiece W is grasped. In this case, the weight of the workpiece W can be accurately measured at the timing when the workpiece W is grasped. Furthermore, when worker M is detected in area A2 while the robot 10 is transporting the workpiece W, the robot 10 temporarily stops and measures the weight of the workpiece W. However, by measuring the weight at the timing when the workpiece W is grasped, the takt time for transporting the workpiece W can be shortened.

[0047] FIG. 6(b) is a diagram showing a method for measuring the weight of the workpiece W at the pick position. When the hand 11 grips the workpiece W at the pick position, a load F equivalent to the weight of the workpiece W is detected. Therefore, the load F at this time can be taken as the weight of the workpiece W. Then, as shown in FIG. 6(c), the measurement unit 152 sets the load F as the reference load. Then, when the control unit 153 detects the worker M in the area A1, it determines whether the robot 10 has come into contact with the worker M based on the reference load. That is, when the load acting on the hand 11 exceeds this reference load, the control unit 153 determines that the robot 10 has come into contact with the worker M. This can also be said to mean that the control unit 153 determines that the robot 10 has come into contact with the worker M when it detects a load that is greater than the measured weight of the workpiece W.

[0048] 7(a) and 7(b) are diagrams explaining in more detail the processes of S505 to S507 and S510 to S512 in FIG. FIG. 7(a) shows a case where worker M is in area A2 while workpiece W is being transported. As described in S506 to S507 and S511 to S512 of FIG. 5, when a worker M is detected in area A2 while the robot 10 is transporting the workpiece W, the control unit 153 temporarily suspends the operation of the robot 10. Furthermore, the measurement unit 152 measures the weight of the workpiece W. This allows the robot 10 to measure the weight of the workpiece W before the worker M enters area A1, where the robot 10 can operate with the worker M, and before the collaborative robot needs to distinguish between the workpiece W and other loads. In other words, the weight of the workpiece W can be measured when there is a risk of contact between the robot 10 and the worker M. Therefore, because the weight of the workpiece W can be measured at an appropriate time while the robot 10 is operating, there is no need to measure the weight of each workpiece W in advance and register it in the system, even when handling a mixed load of workpieces W with various weights, which makes it possible to efficiently set up the operation of the robot 10. Note that if the weight of the workpiece W is measured once during the transport of the workpiece W, even if the worker M is detected again during the transport of the workpiece W, the weight of the workpiece W has already been measured, so the weight will not be measured again. Furthermore, if the worker M does not enter either area A1 or area A2 during the transport of the workpiece W, the control unit 153 does not stop the operation of the robot 10. This can also be said to mean that when worker M is detected in area A2 while the hand 11 is gripping and moving the workpiece W, the control unit 153 temporarily stops the movement of the hand 11, and the measurement unit 152 measures the weight of the workpiece W. In this case, the measurement unit 152 determines that the load F when the hand 11 is stopped is the weight of the workpiece W. In this case, the measurement unit 152 can accurately measure the weight of the workpiece W. Also, the weight of the workpiece W can be reliably measured before worker M enters area A1.

[0049] FIG. 7(b) is a diagram showing a method for measuring the weight of the workpiece W by temporarily stopping the operation of the robot 10. When the hand 11 measures the weight of the workpiece W while moving, a load F greater than or less than the weight of the workpiece W is detected. However, after the hand 11 stops, a load F equal to the weight of the workpiece W is detected. Therefore, the load F at this time can be taken as the weight of the workpiece W. Thereafter, the measurement unit 152 sets the load F as the reference load, and when the control unit 153 detects the worker M in the area A1, the process of determining whether the robot 10 has come into contact with the worker M based on the reference load is the same as in the case of Figure 6(c).

[0050] In the above-described embodiment, the memory unit 154 records information about area A1, which is a collaboration area within the detection range of the sensor 14 where the robot 10 and the work body collaborate, and when the control unit 153 receives sensor information that the input unit 151 has detected a worker M outside area A1 while the hand 11 is holding the work W, it can also be said that the control unit 153 causes the measurement unit 152 or a measurement device to measure the load caused by the work W.

[0051] In the above embodiment, the case where contact between the robot 10 and the worker M is detected has been described, but as mentioned above, contact between the robot 10 and equipment such as a forklift may also be detected. That is, contact with the worker M or a work object including this equipment may also be detected. Therefore, according to the embodiment described above, it is possible to provide a robot system 1 and a control device 15 that can accurately detect contact between the robot 10 and the workpiece by measuring the weight of the workpiece W to be transferred, compared to when this configuration is not adopted.

[0052] <Control method explanation> The processing performed by the control device 150 is realized by the cooperation of software and hardware resources. That is, a processor such as a CPU provided in the control device 15 loads into a main memory and executes a program that realizes each function of the control device 15, thereby realizing each function. Therefore, the processing performed by the control device 15 described above can be understood as a control method characterized in that the control device 15 is connected to the robot 10, the hand 11 provided on the robot 10, a measuring device that measures external forces acting on the hand 11 or the robot 10, and a sensor 14 that detects a workpiece within a predetermined range around the robot 10, and has an input unit 151 that receives information from the sensor 14, a control unit 153, and a memory unit 154, the memory unit 154 stores information on area A1, which is a collaboration area within the detection range of the sensor 14 where the robot 10 and the workpiece collaborate, and the control unit 153 causes the measuring device to measure the weight of the workpiece W when it receives sensor information that the input unit 151 has detected a worker M outside area A1 while the hand 11 is holding the workpiece W. This provides a control method that can accurately detect contact between the robot 10 and the workpiece by measuring the weight of the workpiece W to be transferred, compared to a case where this configuration is not adopted.

[0053] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0054] 1...Robot system, 10...Robot, 11...Hand, 12...Arm, 13...Housing, 14...Sensor, 15...Control device, 16...Display unit, 17...Outrigger, 151...Input unit, 152...Measuring unit, 153...Control unit, 154...Memory unit, M...Worker, W...Work, P...Pallet, Co...Conveyor, A1, A2...Area

Claims

1. 1. A robotic system comprising: a robot, a hand provided on the robot, a sensor that detects a workpiece within a predetermined range around the robot, an input unit that receives information from the sensor, a measurement unit that measures an external force acting on the hand or the robot, a control unit, and a memory unit; The storage unit stores information about a first area that is a collaboration area within the detection range of the sensor where the robot and the working body collaborate, The control unit causes the measurement unit to measure the weight of the workpiece when the input unit receives sensor information indicating that the workpiece is detected outside the first area while the hand is holding the workpiece.

2. 2. The robot system according to claim 1, wherein when a workpiece is detected while the hand is gripping and moving the workpiece, the control unit temporarily stops the movement of the hand and the measuring unit measures the weight of the workpiece.

3. The robot system according to claim 2 , wherein the measuring unit determines the load when the hand is stopped as the weight of the workpiece.

4. 3. The robot system according to claim 2, wherein the control unit measures the weight of the workpiece when grasping the workpiece when the input unit receives sensor information indicating that the input unit has detected a workpiece outside the first area when the hand is not grasping the workpiece.

5. Further, the second area is set outside the first area, The robot system according to claim 2 , wherein when a workpiece is detected in the second area, the control unit temporarily stops the movement of the hand, and the measurement unit measures the weight of the workpiece.

6. The robot system according to claim 5 , wherein the control unit determines that the robot has come into contact with the workpiece when the control unit detects the workpiece in the first area.

7. The robot system according to claim 5, further comprising a stop area where the robot is stopped when a workpiece is detected.

8. The robot system according to claim 7 , wherein the stopping area is set around a workpiece placement area.

9. 2. The robot system according to claim 1, wherein the control unit determines that the robot and the workpiece have come into contact when a load greater than the measured weight of the workpiece is detected.

10. The robot system according to claim 1 , wherein the sensor is attached to a tip of an outrigger extending from a housing of the robot system.

11. a robot; a hand provided on the robot; a measuring device that measures an external force acting on the hand or the robot; an input unit that is connected to a sensor that detects a workpiece within a predetermined range around the robot and that receives information from the sensor; a control unit; and a storage unit; The storage unit stores information about a first area that is a collaboration area within the detection range of the sensor where the robot and the working body collaborate, The control unit is characterized in that when the input unit receives sensor information indicating that a worker is detected outside the first area while the hand is gripping the workpiece, the control unit causes the measuring device to measure the weight of the workpiece.

12. The control device is connected to a robot, a hand provided on the robot, a measuring device that measures external forces acting on the hand or the robot, and a sensor that detects a workpiece within a predetermined range around the robot, and the control device has an input unit that receives information from the sensor, a control unit, and a memory unit, The storage unit stores information about a first area that is a collaboration area within the detection range of the sensor where the robot and the working body collaborate, The control method is characterized in that the control unit causes the measuring device to measure the weight of the workpiece when the input unit receives sensor information that indicates that a worker is detected outside the first area while the hand is gripping the workpiece.

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