Robot System

Abstract

To provide a robot system capable of efficiently avoiding contact between a person and a robot without making complicated advance preparations when changing the operation of the robot. [Solution] A robot system 1 includes a robot 2, a control device 3 that controls the operation of the robot 2, and sensors 4a and 4b that measure the distance to an object within a fixed range in a substantially horizontal direction. The control device 3 acquires current measurement values ​​from the sensors 4a and 4b, calculates the current arm position of the robot 2, projects a point based on the current measurement values ​​and a figure based on the current arm position onto a projection plane perpendicular to the vertical direction, determines whether the distance between the point based on the current measurement values ​​and the figure based on the current arm position is equal to or less than a threshold, and if it is equal to or less than the threshold, executes a monitoring process that stops the operation of the robot 2.

Description

[Technical Field]

[0001] The present invention relates to a robot system having a function for avoiding contact between a human and a robot. [Background technology]

[0002] Conventionally, collaborative robots are an example of robots that can share a space with workers and operate without a safety fence. The control device of a collaborative robot has a function to detect external forces caused by, for example, a collision with a worker during collaborative operation and safely stop the robot. For example, Patent Document 1 discloses a human-collaborative industrial robot that includes a contact force detection unit that detects the contact force applied to the robot when the worker and the robot come into contact, and a contact force monitoring unit that stops the robot or moves the robot away in a direction that reduces the contact force when the contact force exceeds a predetermined threshold.

[0003] Furthermore, even robot systems that do not detect external forces acting on the robot may be able to operate without a safety fence if they use safety devices such as safety laser scanners. Generally, safety laser scanners are safety devices that detect when a worker enters a pre-defined detection area. In conventional robot systems that use safety laser scanners, the robot's control device stops the robot when it receives a signal from the safety laser scanner, i.e., when a person enters the detection area. This allows the robot to be safely stopped before the worker comes into contact with it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-199174 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using a safety laser scanner to prevent contact between humans and robots using conventional methods, sufficient risk assessment and detection area settings are required depending on the robot's movements. When changing the robot's movements, the risk assessment and detection area settings must be performed again, which increases the amount of work required for advance preparation.

[0006] Furthermore, when using a safety laser scanner in the conventional method to avoid contact between humans and robots, it is necessary to set a detection area that covers all positions that the robot arm may operate or enter. If a human enters the detection area, the robot will be stopped even if the human and robot are far apart, which reduces the robot's operating rate.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a robot system that can efficiently avoid contact between humans and the robot without requiring complex advance preparations when changing the robot's operation. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a robot comprising: a control device for controlling the operation of the robot; and a sensor for measuring a distance to an object within a monitoring range that is a certain range in a substantially horizontal direction; the control device pre-stores initial measurement values ​​of the sensors in an initial state before starting the operation of the robot, and executes a monitoring process at a fixed processing cycle while the robot is running; The control device In the monitoring process, obtaining a current measurement value of the sensor; It is determined whether there is a difference between the current measurement value and the initial measurement value, and if there is a difference, A current arm position of the robot is calculated, a point based on the current measurement value and a figure based on the current arm position are projected onto a projection plane perpendicular to the vertical direction, and it is determined whether or not the distance between the point based on the current measurement value and the figure based on the current arm position is equal to or less than a threshold value, and if it is equal to or less than the threshold value, the operation of the robot is stopped. R It is a robot system.

[0009] The sensor measures the distance to the object while changing the angle within the monitoring range, and the control device stores the initial measurement value for each angle in advance. In the monitoring process, the control device acquires the current measurement value for each angle and determines whether there is a difference between the current measurement value and the initial measurement value for each angle. You can do it like this.

[0010] In addition, the control device may be configured to release the suspension of the robot's operation if, during the monitoring process, there is no difference between the current measurement value and the initial measurement value for the entire monitoring range, or if the distance between the point based on the current measurement value and the figure based on the current arm position is greater than a threshold value.

[0011] The robot system may further include an operating device used by a user to operate the robot, and the control device may determine whether or not there is a difference between the current measurement value and the initial measurement value in the robot teaching process, and if there is a difference, notify the operating device that the robot will pass through the monitoring range and accept a decision as to whether or not to cancel the monitoring process. [Effects of the Invention]

[0012] The present invention provides a robot system that can efficiently avoid contact between humans and the robot without requiring complex advance preparations when changing the robot's operation. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a robot system according to an embodiment of the present invention; [Figure 2] Block diagram showing the hardware configuration of the robot system in Figure 1 [Figure 3] 1. A flowchart showing an example of the flow of an initial state storage process realized by the control device of FIG. [Figure 4] FIG. 4 is a plan view illustrating the initial state storage process of FIG. 3; [Figure 5] 1 is a flowchart showing an example of the flow of a monitoring process implemented by the control device of FIG. 1. [Figure 6] FIG. 6 is a diagram illustrating the process of step S15 in FIG. 5; [Figure 7] 1. A flowchart showing an example of the flow of a teaching process implemented by the control device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of a robot system according to this embodiment. As shown in FIG. 1, the robot system 1 includes a robot 2, a control device 3 that controls the operation of the robot 2, and sensors 4a and 4b that measure information indicating the distance from the robot's own position to an object. The object includes a person. The robot system 1 may also include an operation device 5 that a user uses to operate the robot 2. In the example shown in FIG. 1, a roughly rectangular parallelepiped workbench 6 is installed in front of the robot 2. The workbench 6 is a platform on which a workpiece (not shown) or the like is placed.

[0015] The Z axis in FIG. 1 indicates the vertical direction. The X and Y axes are perpendicular to the Z axis and perpendicular to each other. That is, the plane formed by the X and Y axes is perpendicular to the vertical direction. The robot 2 is installed on a plane that is approximately perpendicular to the vertical direction.

[0016] The robot 2 is, for example, a vertical articulated robot with six joints. The robot 2 has a base 21 placed on the floor or the like, an arm 22 connected to the base 21, and a tool 23 attached to the tip of the arm 22. The arm 22 has multiple joints and is configured with a link mechanism having multiple links. Each joint connects a pair of adjacent links and is driven by a power mechanism (motor, reducer, bearing, gears, etc.) to rotate the pair of links relative to one another. The tool 23 is, for example, a gripping hand that can grip a workpiece or the like. Note that the embodiments of the present invention are applicable regardless of the number of joints of the robot 2 or the type of the tool 23.

[0017] The control device 3 may be mounted inside the robot 2 or installed outside the robot 2. The number of control devices 3 may be one or more. In the case of multiple control devices, the control devices 3 are connected to each other so that they can communicate with each other. In the example shown in FIG. 1, the control device 3 is installed outside the robot 2, and there is one control device 3 in total.

[0018] The sensors 4a and 4b irradiate a laser beam over a certain range in a substantially horizontal direction (i.e., a direction substantially parallel to the plane on which the robot 2 is installed) and measure the distance to an object for each angle of the laser beam. The sensors 4a and 4b are, for example, safety devices such as safety laser scanners. The sensors 4a and 4b project a laser beam using a projector, receive the reflected light from the object using a receiver, and calculate the distance from their own position to the object by measuring the time between projecting and receiving the light. The sensors 4a and 4b can detect the presence of surrounding objects by calculating the distance by gradually changing the angle in a fan-like manner. In the example shown in FIG. 1, the number of sensors 4a and 4b is two, but the number may be one or three or more. The sensors 4a and 4b are installed, for example, on both side surfaces 21a and 21b of the base 21 of the robot 2. Note that the embodiment of the present invention is applicable regardless of the installation location of the sensors 4a and 4b. Furthermore, the sensors 4a and 4b are not limited to safety laser scanners, but may be any device that emits radio waves, such as millimeter wave radar, as long as it can measure the distance to an object.

[0019] The operation device 5 is a terminal that can be carried by the user and is also called a teaching pendant. The operation device 5 is used to teach the robot 2 work content (teaching) and to play back the content that has been taught to the robot 2. The robot 2 operates in a teaching mode or a playback mode according to the instructions of the operation device 5. The operation device 5 may be a button type in which information is displayed on a non-touch panel display and operated with physical buttons, or a touch panel type that uses a mobile terminal such as a general-purpose tablet terminal or smartphone with a touch panel display. The operation device 5 in FIG. 2 is a touch panel type. Note that the embodiments of the present invention are applicable regardless of the type of operation device 5.

[0020] The control device 3 is communicatively connected to the robot 2, the sensors 4a and 4b, and the operating device 5. The control device 3 may be connected to each device via a wired communication cable, or may be connected to each device wirelessly.

[0021] Figure 2 is a block diagram showing the hardware configuration of the robot system of Figure 1. The robot 2 has, for each joint, a motor 24 that rotates in accordance with commands from the control device 3, and an encoder 25 that detects the rotation angle of the motor 24 and outputs the shaft angle of each joint shaft to the control device 3.

[0022] The control device 3 has a processor 31, a memory 32, an auxiliary storage device 33, and an input / output interface 34, which are connected via a bus 35. The processor 31 is a CPU (Central Processing Unit) or the like, and reads a computer program stored in advance in the auxiliary storage device 33 or the like into the memory 32 and sequentially executes a plurality of instructions. The memory 32 is a volatile memory such as a semiconductor memory, and is a storage device to and from which the processor 31 can directly read and write data. The auxiliary storage device 33 is a computer-readable non-transitory storage medium such as a hard disk drive, solid-state drive, or USB (Universal Serial Bus) memory, and stores computer programs and data. The input / output interface 34 is an external connection device used for inputting and outputting signals to and from the robot 2, sensors 4a and 4b, operation device 5, etc.

[0023] The operation device 5 has a processor 51, memory 52, auxiliary storage device 53, touch panel 54, and input / output interface 55, which are connected via a bus 56. The processor 51, memory 52, and auxiliary storage device 53 are similar to the processor 31, memory 32, and auxiliary storage device 33 of the control device 3, so their description will be omitted. The touch panel 54 is an input device integrated with a display device such as a liquid crystal display, and displays data and accepts data input by touch operation. The input / output interface 55 is an external connection device used for inputting and outputting signals to and from the control device 3, etc. Although not shown in FIG. 2, the operation device 5 also has an emergency stop switch that instructs the robot 2 to stop in an emergency, and an enable switch that enables operation of the robot 2.

[0024] All or part of the functions of the control device 3 and the operation device 5 may be configured with logic circuits or analog circuits. Furthermore, the control device 3 and the operation device 5 may process various programs with electronic circuits such as FPGAs (Field Programmable Gate Arrays). Furthermore, the control device 3 and the operation device 5 may include devices not shown in FIG. 2, such as wireless communication devices and speakers.

[0025] Fig. 3 is a flowchart showing an example of the flow of the initial state storage process realized by the control device of Fig. 1. The initial state storage process is a process in which the control device 3 stores initial measurement values ​​indicating the distance to an object for each irradiation angle of the laser light from the sensors 4a and 4b in the initial state before starting the operation of the robot 2. The control device 3 executes the process shown in Fig. 3 for each of the sensors 4a and 4b.

[0026] As shown in FIG. 3, the processor 31 of the control device 3 sets the initial irradiation angle (step S1). Next, the processor 31 acquires the initial measurement values ​​of the sensors 4a and 4b (step S2) and stores the initial measurement values ​​of the sensors 4a and 4b in the auxiliary storage device 33 (step S3). Next, the processor 31 checks whether the initial measurement values ​​have been stored for all irradiation angles (step S4). If the processor 31 has not stored the initial measurement values ​​for all irradiation angles (No in step S4), the processor 31 sets the next irradiation angle (step S5) and repeats the process from step S2. On the other hand, if the processor 31 has stored the initial measurement values ​​for all irradiation angles (Yes in step S4), the processor 31 ends the process.

[0027] Fig. 4 is a plan view for explaining the initial state storage process of Fig. 3. Fig. 4 does not show the arm 22 and tool 23 of the robot 2, the control device 3, or the operating device 5, but shows only the base 21 of the robot 2, the sensors 4a and 4b, and the work table 6. The maximum irradiation angle range of the sensors 4a and 4b is, for example, 270 degrees, and the sensors 4a and 4b are installed on both side surfaces 21a and 21b of the base 21, so that it is possible to monitor almost the entire surroundings of the robot 2. Even when the sensors 4a and 4b are installed at positions away from the robot 2, it is possible to monitor almost the entire surroundings of the robot 2 by installing the two sensors 4a and 4b at positions facing each other with the robot 2 in between.

[0028] The irradiation angles of the sensors 4a and 4b are the angles α and β formed between the reference directions 41a and 41b and the laser beam irradiation directions 42a and 42b. The monitoring ranges 44a and 44b of the sensors 4a and 4b are determined by the monitoring distance (within the maximum irradiation distance) and monitoring angle range (within the maximum irradiation angle range) set for the sensors 4a and 4b. The measurement values ​​Ca and Cb of the sensors 4a and 4b are the distances from the laser beam irradiation position to points 43a and 43b where the laser beam is reflected by an object. The measurement values ​​Ca and Cb of the sensors 4a and 4b shown in FIG. 4 are the distances to the workbench 6. When no object is present within the monitoring distance, the measurement values ​​Ca and Cb of the sensors 4a and 4b are the same as the monitoring distance. Note that the monitoring ranges 44a and 44b actually extend up and down along the Z axis by a predetermined emission angle range, centered on the laser beam emission points of the sensors 4a and 4b.

[0029] The control device 3 stores in advance the initial measurement values ​​of the sensors 4a and 4b in the initial state before starting the operation of the robot 2 through the process of Fig. 3. The processor 31 of the control device 3 stores, for example, the measurement values ​​Ca and Cb in the auxiliary storage device 33 as polar coordinates (α, Ca) and (β, Cb). The process of Fig. 3 must be performed every time the environment around the robot 2 changes, but since it is performed automatically by the control device 3, the user does not need to perform any complicated advance preparations.

[0030] FIG. 5 is a flowchart showing an example of the flow of a monitoring process implemented by the control device of FIG. 1. The control device 3 executes the monitoring process of FIG. 5 at a fixed cycle while the robot 2 is running. To execute the monitoring process of FIG. 5, the control device 3 stores the link parameters of the robot 2, shape information of the arm 22 (such as the dimensions and weight of each part), and the installation positions of the sensors 4a and 4b in the auxiliary storage device 33. The link parameters include the inter-link distance, link torsion angle, and link length, and are, for example, DH parameters using the Denavit-Hartenberg notation (DH method). The installation positions of the sensors 4a and 4b are, for example, coordinates in the robot coordinate system (Xr, Yr, Zr) of the robot 2. The processor 31 of the control device 3 reads this data from the auxiliary storage device 33 to the memory 32 before executing the monitoring process of FIG. 5.

[0031] As shown in FIG. 5, the processor 31 of the control device 3 sets an initial irradiation angle (step S11). Next, the processor 31 acquires the current measurement values ​​of the sensors 4a and 4b (step S12) and checks whether there has been a change from the initial state (step S13). Specifically, the processor 31 determines whether there is a difference between the current measurement values ​​and the initial measurement values ​​of the sensors 4a and 4b for the same irradiation angle. If there is a difference between the current measurement values ​​and the initial measurement values ​​(Yes in step S13), the processor 31 proceeds to step S14, and if there is no difference (No in step S13), the processor 31 proceeds to step S17. If the determination process in step S13 determines that the robot 2 has simply approached an object (e.g., workbench 6) that has been present since the initial state, the operation of the robot 2 does not need to be stopped.

[0032] In step S14, the processor 31 acquires each axis angle from the robot 2, and performs forward kinematics calculations using the data on each axis angle, link parameters, and arm shape. The processor 31 then analytically calculates the position of each part of the robot 2 (each joint axis, the tool 23, etc.), and calculates the current arm position in the robot coordinate system (Xr, Yr, Zr) of the robot 2. The current arm position is, for example, the position of the tool center point (TCP), which is the coordinate center of the tip of the tool 23. Furthermore, the current arm position is not limited to one point, and may include the positions of each joint axis in addition to the position of the TCP.

[0033] Next, the processor 31 checks whether the distance between the position related to the current measurement value in step S13 and the current arm position in step S14 is equal to or less than a threshold value (step S15).

[0034] Fig. 6 is a diagram for explaining the processing of step S15 in Fig. 5. The projection plane 7 shown in Fig. 6 is a plane that is approximately parallel to the plane on which the robot 2 is installed. More specifically, the projection plane 7 shown in Fig. 6 is a plane that is perpendicular to the vertical direction, for example, a plane formed by the Xr axis and the Yr axis that are perpendicular to the Zr axis in the vertical direction in the robot coordinate system (Xr, Yr, Zr) of the robot 2.

[0035] Da (Xda, Yda) and Db (Xdb, Ydb) are points indicating the installation positions of sensors 4a and 4b, respectively. E (Xe, Ye) is a point based on the current arm position in step S14, i.e., the foot of a perpendicular line dropped from the current arm position onto the projection plane 7. Processor 31 converts the current measurement values ​​(α, Ca) and (β, Cb) of sensors 4a and 4b in step S13 from polar coordinates to Cartesian coordinates and projects them onto the projection plane 7. Fa (Xfa, Yfa) and Fb (Xfa, Xfb) are points based on the current measurement values ​​of sensors 4a and 4b. Here, processor 31 shifts the positions from origin O by the coordinates Da (Xa, Ya) and Db (Xb, Yb) indicating the installation positions of sensors 4a and 4b, and projects Fa (Xfa, Yfa) and Fb (Xfa, Xfb).

[0036] Then, the processor 31 calculates the distances Ga and Gb between points Fa (Xfa, Yfa) and Fb (Xfa, Xfb) based on the current measurement values ​​and point E (Xe, Ye) based on the current arm position, and determines whether or not the distances are equal to or less than a threshold value. In the example of FIG. 6, the positions of objects 8a and 8b are both within the movable range of the arm 22 of the robot 2. In the case of object 8a, since it is approaching the arm position, it is necessary to stop the operation of the robot 2. On the other hand, in the case of object 8b, since it is far from the arm position, it is not necessary to stop the operation of the robot 2.

[0037] 6, the processor 31 projects a point onto the projection plane 7 based on the current arm position, but it may also project a line, a circle, an ellipse, a polygon, etc. For example, the processor 31 may calculate the positions of the TCP and each joint axis as the current arm position, and project a line connecting the TCP and each joint axis, or a circle, ellipse, polygon, etc. representing the shape of the arm 22 onto the projection plane 7.

[0038] In other words, processor 31 projects points based on the current measurement values ​​and a figure based on the current arm position onto projection plane 7, and determines whether the distance between the points based on the current measurement values ​​and the figure based on the arm position is equal to or less than a threshold. Figures based on the arm position include planar figures such as points, lines, circles, ellipses, and polygons. The distance is, for example, the shortest Euclidean distance between the points and the figure.

[0039] Returning to the explanation of Figure 5, if the distance between the point based on the current measurement value and the figure based on the current arm position is equal to or less than the threshold value (Yes in step S15), processor 31 sends a command to robot 2 to stop the operation of robot 2 (step S16) and ends the processing. On the other hand, if the distance between the point based on the current measurement value and the figure based on the current arm position is greater than the threshold value (No in step S15), processor 31 proceeds to step S17.

[0040] In step S17, processor 31 checks whether the processing from steps S12 to S16 has been performed for all irradiation angles. If not all irradiation angles have been processed (No in step S17), processor 31 sets the next irradiation angle (step S18) and repeats the processing from step S12. On the other hand, if all irradiation angles have been processed (Yes in step S17), processor 31 sends a command to robot 2 to release the suspension of robot 2 movement (step S19) and terminates processing. That is, processor 31 releases the suspension of robot 2 movement if there is no difference between the current measurement value and the initial measurement value for all irradiation angles, or if the distance between the point based on the current measurement value and the figure based on the current arm position is greater than the threshold value. This allows control device 3 to automatically resume the movement of robot 2 once the object and robot 2 are separated.

[0041] Fig. 7 is a flowchart showing an example of the flow of the teaching process realized by the control device of Fig. 1. If the robot 2 moves to a position that blocks the laser beams of the sensors 4a and 4b during the monitoring process of Fig. 5, the control device 3 stops the operation of the robot 2, and the robot 2 cannot perform the desired operation. Therefore, in the teaching process of Fig. 7, if the instruction from the user is to move the robot 2 to a position that blocks the laser beams of the sensors 4a and 4b, the control device 3 receives, via the operation device 5, an instruction as to whether or not to cancel the monitoring process of Fig. 5.

[0042] As shown in FIG. 7, the processor 31 of the control device 3 sends a command to the robot 2 to move to the initial teaching point in accordance with an instruction from the operating device 5 (step S21). Next, the processor 31 acquires the current measurement values ​​of the sensors 4a and 4b (step S22) and checks whether there has been a change from the initial state (step S23). More specifically, similar to step S13 in FIG. 5, the processor 31 determines whether there is a difference between the current measurement values ​​and the initial measurement values ​​of the sensors 4a and 4b for the same irradiation angle. The processor 31 executes the processes of steps S22 and S23 for all irradiation angles. If there is a difference between the current measurement values ​​and the initial measurement values ​​at any irradiation angle (Yes in step S23), the processor 31 proceeds to step S24. If there is no difference at all irradiation angles (No in step S23), the processor 31 proceeds to step S27.

[0043] In step S24, the processor 31 notifies the operation device 5 that the robot 2 will pass through the monitoring range (step S24). In response to this, the processor 51 of the operation device 5 displays on the touch panel 54 that the robot 2 will pass through the monitoring range. Then, the processor 51 receives an instruction from the user via the touch panel 54 as to whether or not to cancel the monitoring process.

[0044] The processor 31 checks whether an instruction to cancel the monitoring process has been issued (step S25). If an instruction to cancel has been issued (Yes in step S25), the processor 31 stores the timing of canceling the monitoring process (step S26) and proceeds to step S27. The processor 31 stores, for example, the movement operation from the previous teaching point to the current teaching point as the timing of canceling the monitoring process in the auxiliary storage device 33. If an instruction to cancel has not been issued (No in step S25), the control device 3 proceeds to step S27 without taking any action. Alternatively, the control device 3 may accept a reset of the current teaching point before proceeding to step S27 and repeat the process from step S22.

[0045] In step S27, processor 31 confirms whether or not to continue the teaching work. If processor 31 decides to continue the teaching work (Yes in step S27), it sends a command to robot 2 to move to the next teaching point in accordance with an instruction from operating device 5 (step S28), and repeats the processing from step S22. On the other hand, if processor 31 decides not to continue the teaching work (No in step S27), it ends the processing.

[0046] 7, when the control device 3 receives a request to cancel the monitoring process, the control device 3 does not execute the monitoring process at the timing when the cancellation is received when operating the robot 2 according to the instruction content. When the control device 3 receives the cancellation, the control device 3 may, for example, issue a warning sound indicating that the cancellation is being performed, or may slow down the operating speed of the robot 2.

[0047] In the example of Fig. 7, the control device 3 notifies the user that the robot 2 will pass through the monitoring range for each teaching point. However, the control device 3 may notify the user of the timing when the robot 2 will pass through the monitoring range after setting all teaching points has been completed. For example, when the control device 3 receives an instruction to play back all teaching points from the operation device 5, it executes steps S22 and S23 in Fig. 7 at a fixed processing cycle and stores the timing when the robot 2 will pass through the monitoring range. Then, when playback of all teaching points has been completed, the control device 3 transmits the timing when the robot 2 will pass through the monitoring range to the operation device 5. The operation device 5 notifies the user of the timing when the robot 2 will pass through the monitoring range and accepts the user's instruction to cancel the monitoring process or reset the teaching points.

[0048] As described above, the robot system 1 according to an embodiment of the present invention includes a robot 2, a control device 3, and sensors 4a and 4b that measure the distance to an object within a monitoring range that is a fixed range in a substantially horizontal direction. The control device 3 acquires current measurement values ​​from the sensors 4a and 4b, calculates the current arm position of the robot 2, and projects a point based on the current measurement values ​​and a figure based on the current arm position onto a projection plane that is substantially parallel to a plane perpendicular to the vertical direction. The control device 3 then determines whether the distance between the point based on the current measurement values ​​and the figure based on the current arm position is equal to or less than a threshold. If the distance is equal to or less than the threshold, the control device 3 executes a monitoring process that stops the operation of the robot 2. This allows for efficient avoidance of contact between humans and the robot 2 without complex advance preparations when changing the operation of the robot 2. In particular, even if a human enters the robot 2's movement range, the operation of the robot 2 is not stopped as long as the human is away from the robot 2, thereby preventing a decrease in the operating rate of the robot 2.

[0049] Furthermore, the control device 3 pre-stores the initial measurement values ​​of the sensors 4a and 4b in the initial state before starting the operation of the robot 2. Then, in the monitoring process, the control device 3 determines whether there is a difference between the current measurement value and the initial measurement value, and if there is a difference, determines whether the distance between the point based on the current measurement value and the figure based on the arm position is equal to or less than a threshold, and if it is equal to or less than the threshold, stops the operation of the robot 2. The initial state storage process for pre-storing the initial measurement value needs to be performed every time the environment around the robot 2 is changed, but because it is performed automatically by the control device 3, the user does not have to perform complex advance preparations, reducing the burden on the user.

[0050] Furthermore, in the monitoring process, if there is no difference between the current measurement value and the initial measurement value for the entire monitoring range, or if the distance between the point based on the current measurement value and the figure based on the arm position is greater than a threshold, the control device 3 releases the suspension of the operation of the robot 2. As a result, even if the operation of the robot 2 has been suspended, the control device 3 can automatically resume the operation of the robot 2 once the person moves away from the robot 2.

[0051] The robot system 1 also includes an operating device 5 that the user uses to operate the robot 2. The control device 3 determines whether there is a difference between the current measurement value and the initial measurement value in the teaching process of the robot 2. If there is a difference, the control device 3 notifies the operating device 5 that the robot 2 will pass through the monitoring range of the laser light from the sensors 4a and 4b, and accepts a request as to whether or not to cancel the monitoring process. This allows the user to instruct the robot 2 to move to a position that blocks the laser light from the sensors 4a and 4b without stopping the operation of the robot 2, increasing the degree of freedom in the teaching content of the robot 2.

[0052] The control device 3 may use the monitoring process in the embodiment of the present invention in combination with other external force detection processes or other approach / contact monitoring processes using non-contact sensors, etc. This allows the control device 3 to detect situations that cannot be detected by a single process due to a blind spot, with multiple processes complementing each other.

[0053] While the preferred embodiments of the robot system and the like according to the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas disclosed herein, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0054] 1. Robot system 2. Robot 3...Control device 4a, 4b...Sensor 5……Operating device 7……Projection plane 22……Projection plane 44a, 44b...Monitoring range Ca, Cb: Distance to object E: Graphic based on the current arm position Fa, Fb...Points based on the current measurement value Ga, Gb: Distance between the point based on the current measurement value and the figure based on the current arm position

Claims

1. Robots and a control device for controlling the operation of the robot; a sensor that measures the distance to an object within a certain range in a substantially horizontal direction; Equipped with the control device pre-stores initial measurement values ​​of the sensors in an initial state before starting the operation of the robot, and executes a monitoring process at a fixed processing cycle while the robot is running; In the monitoring process, the control device acquires the current measurement value of the sensor, determines whether there is a difference between the current measurement value and the initial measurement value, and if there is a difference, calculates the current arm position of the robot, projects a point based on the current measurement value and a figure based on the current arm position onto a projection plane perpendicular to the vertical direction, determines whether the distance between the point based on the current measurement value and the figure based on the current arm position is equal to or less than a threshold, and if it is equal to or less than the threshold, stops the operation of the robot. A robot system characterized by:

2. The sensor measures the distance to the object by changing the angle within the monitoring range, the control device stores the initial measurement value for each angle in advance, In the monitoring process, the control device acquires the current measurement value for each angle and determines whether or not there is a difference between the current measurement value and the initial measurement value for each angle.

2. The robot system according to claim 1.

3. In the monitoring process, if there is no difference between the current measurement value and the initial measurement value for the entire monitoring range, or if the distance between the point based on the current measurement value and the figure based on the current arm position is greater than a threshold, the control device cancels the stop of the robot's operation.

2. The robot system according to claim 1.

4. An operation device that a user uses to operate the robot, The control device determines whether or not there is a difference between the current measurement value and the initial measurement value in the teaching process of the robot, and if there is a difference, notifies the operation device that the robot will pass through the monitoring range and accepts a request to cancel the monitoring process.

2. The robot system according to claim 1.

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