robot systems

Abstract

This system provides a robot that can efficiently avoid contact between humans and robots without requiring complex preparations when changing the robot's movements. [Solution] The robot system 1 comprises a robot 2, a control device 3 that controls the movement of the robot 2, and sensors 4a and 4b that measure the distance to an object with a fixed range in a substantially horizontal direction as the monitoring range. The control device 3 acquires the current measurement values ​​from sensors 4a and 4b, calculates the current arm position of the robot 2, 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 below a threshold, and if it is below the threshold, executes a monitoring process to stop the movement of the robot 2.

Description

Technical Field

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

Background Art

[0002] Conventionally, as an example of a robot that can share a space with an operator and operate without a safety fence, there is a collaborative robot. The control device of the collaborative robot has a function of detecting an external force caused by a collision with an operator or the like during collaborative operation and safely stopping the robot. For example, Patent Document 1 discloses a human-cooperative industrial robot including a contact force detection unit that detects a contact force applied to the robot when the operator contacts the robot, and a contact force monitoring unit that stops the robot or retreats the robot in a direction to reduce the contact force when the contact force exceeds a predetermined threshold value.

[0003] Also, even in a robot system that does not detect an external force applied to the robot, it may be possible to operate without a safety fence by using a safety device such as a safety laser scanner. Generally, a safety laser scanner is a safety device that detects that an operator has entered a preset detection area. In a conventional robot system using a safety laser scanner, the control device of the robot stops the robot at the timing when a signal is input from the safety laser scanner, that is, at the timing when a person enters the detection area. Thereby, the robot can be safely stopped before the operator makes contact.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when using conventional methods to avoid contact between people and robots using safety laser scanners, a thorough risk assessment and detection area setting are required depending on the robot's movement. When the robot's movement is changed, the risk assessment and detection area setting must be repeated, increasing the amount of preparation work required.

[0006] Furthermore, when using conventional methods to avoid contact between people and robots using safety laser scanners, it is necessary to set up a detection area that covers all locations where the robot arm may operate or enter. If a person enters the detection area, the robot will stop even if the person and robot are far apart, which reduces the robot's operational efficiency.

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

[0008] To achieve the aforementioned objectives, the present invention comprises a robot, a control device for controlling the robot's movement, and a sensor for measuring the distance to an object with a fixed range in a substantially horizontal direction as its monitoring range. The control device acquires the current measurement value from the sensor, 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 below a threshold, and if it is below the threshold, executes a monitoring process to stop the robot's movement.

[0009] The control device may store in advance the initial measurement value of the sensor in the initial state before the robot starts moving, and in the monitoring process, determine whether there is a difference between the current measurement value and the initial measurement value. If there is a difference, it may determine whether the distance between the point based on the current measurement value and the figure based on the current arm position is below a threshold, and if it is below the threshold, it may stop the robot's movement.

[0010] Furthermore, the control device may, in the monitoring process, release the stop of the robot's movement if, for all of the monitoring ranges, there is no difference between the current measurement value and the initial measurement value, 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.

[0011] The robot system may further include an operating device used by the user to operate the robot, and the control device may determine whether there is a difference between the current measurement value and the initial measurement value during the robot teaching process, and if there is a difference, notify the operating device that the robot is passing through the monitoring range and accept 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 robots without requiring complex preparations when changing the robot's movements. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the overall configuration of the robot system according to this embodiment. [Figure 2] Block diagram showing the hardware configuration of the robot system in Figure 1. [Figure 3] A flowchart showing an example of the initial state storage process implemented by the control device in Figure 1. [Figure 4] Plan view illustrating the initial state storage process shown in Figure 3. [Figure 5]A flowchart showing an example of the monitoring process flow implemented by the control device in Figure 1. [Figure 6] Figure 5 is a diagram illustrating the process of step S15. [Figure 7] A flowchart showing an example of the teaching process flow realized by the control device in Figure 1. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a diagram showing the overall configuration of a robot system according to this embodiment. As shown in Figure 1, the robot system 1 comprises a robot 2, a control device 3 for controlling the movement of the robot 2, and sensors 4a and 4b for measuring information indicating the distance from its own position to an object. The object includes a person. The robot system 1 may also be equipped with an operating device 5 used by the user to operate the robot 2. In the example shown in Figure 1, a roughly rectangular 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] In Figure 1, the Z-axis represents the vertical direction. The X-axis and Y-axis are perpendicular to the Z-axis and also perpendicular to each other. That is, the plane formed by the X-axis and Y-axis is perpendicular to the vertical direction. Robot 2 is positioned in a plane that is approximately perpendicular to the vertical direction.

[0016] Robot 2 is, for example, a vertical articulated robot with 6 joints. Robot 2 has a base 21 installed on the floor or the like, an arm 22 connected to the base 21, and a tool 23 attached to the end of the arm 22. The arm 22 has multiple joints and is composed of a linkage mechanism with multiple links. Each joint connects a pair of adjacent links and is driven by a power mechanism (motor, reducer, bearing, gear, etc.) to rotate the pair of links relative to each other. The tool 23 is, for example, a gripping hand capable of gripping a workpiece or the like. The embodiments of the present invention are applicable regardless of the number of joints of robot 2 or the type of tool 23.

[0017] Furthermore, the control device 3 may be mounted inside the robot 2 or installed outside the robot 2. Also, the number of control devices 3 may be one or plural. In the case of plural control devices 3, they are connected to be able to communicate with each other. In the example shown in FIG. 1, the control device 3 is installed outside the robot 2 and the number is one.

[0018] The sensors 4a and 4b irradiate laser light with a certain range in a substantially horizontal direction (a direction substantially parallel to the plane on which the robot 2 is installed) as a monitoring range, and measure the distance to an object for each irradiation angle of the laser light. The sensors 4a and 4b are, for example, safety devices such as a safety laser scanner. The sensors 4a and 4b project beam-shaped laser light by a projector, receive the reflected light from an object with a light receiver, and calculate the distance from their own position to the object by measuring the time from projection to reception. The sensors 4a and 4b can detect the presence of surrounding objects by calculating the distance while slightly changing the angle little by little in a fan shape. In the example shown in FIG. 1, the number of sensors 4a and 4b is two, but it may be one or three or more. The sensors 4a and 4b are installed on both side surfaces 21a and 21b of the base 21 of the robot 2, for example. Note that the embodiment of the present invention is applicable regardless of the installation location of the sensors 4a and 4b. Also, the sensors 4a and 4b are not limited to a safety laser scanner, and may be those that emit radio waves such as a millimeter-wave radar, as long as they can measure the distance to an object.

[0019] The operation device 5 is a terminal that can be carried by a user and is also called a teaching pendant. The operation device 5 is used to teach (teach) the work content to the robot 2 or to reproduce the taught content on the robot 2. The robot 2 operates in a teaching mode or a reproduction mode according to the instructions of the operation device 5. The operation device 5 has a button type in which information is displayed on a display that is not a touch panel and is operated by physical buttons, or a touch panel type using a general-purpose tablet terminal or a mobile terminal such as a smartphone having a touch panel display. The operation device 5 in FIG. 2 is of the touch panel type. Note that the embodiment of the present invention is applicable regardless of the method of the operation device 5.

[0020] The control device 3 is communicably 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] FIG. 2 is a block diagram showing the hardware configuration of the robot system of FIG. 1. The robot 2 includes, for each joint, a motor 24 that rotates according to a command from the control device 3, and an encoder 25 that detects the rotation angle of the motor 24 and outputs the axis angle of each joint axis 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 the auxiliary storage device 33 or the like into the memory 32 in advance, and sequentially executes a plurality of instructions. The memory 32 is a volatile memory such as a semiconductor memory, and is a storage device where the processor 31 can directly read and write data. The auxiliary storage device 33 is a non-temporary storage medium readable by a computer, such as a hard disk drive, a solid state drive, or a USB (Universal Serial Bus) memory, and stores computer programs and data. The input / output interface 34 is an external connection device used for input / output of signals with the robot 2, the sensors 4a and 4b, the operating device 5, and the like.

[0023] The operating device 5 includes 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 the same as those of the processor 31, memory 32, and auxiliary storage device 33 of the control device 3, so their description is omitted. The touch panel 54 is an input device integrated with a display device such as a liquid crystal display, which displays data and accepts data input via touch operation. The input / output interface 55 is an external connection device used for inputting and outputting signals with the control device 3, etc. Although not shown in Figure 2, the operating device 5 also includes an emergency stop switch to instruct the robot 2 to stop in an emergency, and an enable switch to activate the operation of the robot 2.

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

[0025] Figure 3 is a flowchart illustrating an example of the initial state storage process implemented by the control device shown in Figure 1. The initial state storage process is the process by which the control device 3 stores initial measurements indicating the distance to an object for each irradiation angle of the laser beam from sensors 4a and 4b in the initial state before the robot 2 starts moving. The control device 3 executes the process shown in Figure 3 for each of sensors 4a and 4b.

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

[0027] Figure 4 is a plan view illustrating the initial state memory processing shown in Figure 3. Figure 4 shows only the base 21, sensors 4a and 4b, and workbench 6 of the robot 2, excluding the robot's arm 22 and tool 23, control device 3, and operating device 5. The maximum illumination angle range of sensors 4a and 4b is, for example, 270 degrees, and since sensors 4a and 4b are installed on both sides 21a and 21b of the base 21, it is possible to monitor almost the entire area around the robot 2. Even if sensors 4a and 4b are installed at a distance from the robot 2, it is possible to monitor almost the entire area around the robot 2 by installing the two sensors 4a and 4b opposite each other with the robot 2 in between.

[0028] The irradiation angles of sensors 4a and 4b are the angles α and β between the reference directions 41a and 41b and the laser beam irradiation directions 42a and 42b. The monitoring ranges 44a and 44b of 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 sensors 4a and 4b. The measured values ​​Ca and Cb of sensors 4a and 4b are the distances from the laser beam irradiation position to the points 43a and 43b where the laser beam is reflected by an object. The measured values ​​Ca and Cb of sensors 4a and 4b shown in Figure 4 are the distances to the workbench 6. If no object is present within the monitoring distance, the measured values ​​Ca and Cb of sensors 4a and 4b will be the same as the monitoring distance. In reality, the monitoring ranges 44a and 44b extend vertically along the Z-axis by a predetermined range of emission angles, centered on the laser beam emission part of sensors 4a and 4b.

[0029] The control device 3, through the process shown in Figure 3, pre-stores the initial measurements of sensors 4a and 4b in the initial state before the robot 2 starts moving. The processor 31 of the control device 3 stores, for example, the measured values ​​Ca and Cb in polar coordinates (α, Ca) and (β, Cb) in the auxiliary storage device 33. The process shown in Figure 3 needs to be performed each time the environment around the robot 2 is changed, but the control device 3 performs this automatically, so the user does not need to perform any complex preparations.

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

[0031] As shown in Figure 5, the processor 31 of the control device 3 sets the initial irradiation angle (step S11). Next, the processor 31 acquires the current measured values ​​of sensors 4a and 4b (step S12) and checks whether there has been any change from the initial state (step S13). Specifically, the processor 31 determines whether there is a difference between the current measured values ​​and the initial measured values ​​of sensors 4a and 4b for the same irradiation angle. If there is a difference between the current measured values ​​and the initial measured values ​​(Yes in step S13), the processor 31 proceeds to step S14; if there is no difference (No in step S13), it proceeds to step S17. The determination process in step S13 ensures that if the robot 2 has only approached an object that was present from the initial state (=workbench 6, etc.), the robot 2 does not need to stop its operation.

[0032] In step S14, the processor 31 obtains the axis angles from the robot 2 and performs forward kinematic calculations using the axis angles, link parameters, and arm shape data. The processor 31 then analytically calculates the position of each part of the robot 2 (each joint axis, 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 a single point, but may include the positions of each joint axis in addition to the TCP position.

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

[0034] Figure 6 is a diagram illustrating the process of step S15 in Figure 5. The projection plane 7 shown in Figure 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 Figure 6 is a plane perpendicular to the vertical direction, for example, the plane formed by the Xr axis and Yr axis perpendicular to the vertical Zr axis 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 the perpendicular from the current arm position to the projection plane 7. The processor 31 converts the current measured 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 measured values ​​of sensors 4a and 4b. Here, the processor 31 shifts the position from the origin O by the amount of 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] The processor 31 then calculates the distances Ga and Gb between points Fa(Xfa, Yfa) and Fb(Xfa, Xfb) based on the current measurement and point E(Xe, Ye) based on the current arm position, and determines whether or not the distance is below a threshold. In the example in Figure 6, the positions of objects 8a and 8b are both within the movable range of the robot 2's arm 22. In the case of object 8a, since it is approaching the arm position, it is necessary to stop the robot 2's movement. 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 robot 2's movement.

[0037] In the example shown in Figure 6, the processor 31 projects a point onto the projection plane 7 based on the current arm position, but it may also project lines, circles, ellipses, polygons, etc. For example, the processor 31 may calculate the TCP and the positions of each joint axis as the current arm position, and project lines connecting the TCP and each joint axis, or circles, ellipses, polygons, etc. representing the shape of the arm 22, onto the projection plane 7.

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

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

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

[0041] Figure 7 is a flowchart showing an example of the teaching process flow implemented by the control device in Figure 1. During the monitoring process in Figure 5, if the robot 2 moves to a position that blocks the laser light from sensors 4a and 4b, the control device 3 stops the movement of the robot 2, making it impossible to have the robot 2 perform the desired action. Therefore, in the teaching process in Figure 7, if the user's teaching involves moving the robot 2 to a position that blocks the laser light from sensors 4a and 4b, the control device 3 receives a request via the operating device 5 to cancel the monitoring process in Figure 5.

[0042] As shown in Figure 7, the processor 31 of the control device 3 sends a command to the robot 2 to move to the first teaching point in accordance with the instructions from the operating device 5 (step S21). Next, the processor 31 acquires the current measured values ​​of sensors 4a and 4b (step S22) and checks whether there has been any change from the initial state (step S23). Specifically, the processor 31 determines whether there is a difference between the current measured values ​​and the initial measured values ​​of sensors 4a and 4b for the same irradiation angle, similar to step S13 in Figure 5. The processor 31 performs the processes in steps S22 and S23 for all irradiation angles. Then, if there is a difference between the current measured value and the initial measured value for any irradiation angle (Yes in step S23), the processor 31 proceeds to step S24, and if there is no difference for any irradiation angles (No in step S23), it proceeds to step S27.

[0043] In step S24, the processor 31 notifies the operating device 5 that the robot 2 is passing through the monitoring range (step S24). In response, the processor 51 of the operating device 5 displays on the touch panel 54 that the robot 2 is passing through the monitoring range. The processor 51 then receives instructions from the user via the touch panel 54 regarding whether or not to cancel the monitoring process.

[0044] The processor 31 checks whether or not there is an instruction to cancel the monitoring process (step S25). If there is an instruction to cancel (Yes in step S25), the processor 31 stores the timing of the monitoring process cancellation (step S26) and proceeds to step S27. For example, the processor 31 stores the movement operation from the previous teaching point to the current teaching point in the auxiliary storage device 33 as the timing of the monitoring process cancellation. If there is no instruction to cancel (No in step S25), the control device 3 does nothing and proceeds to step S27. Alternatively, before proceeding to step S27, the control device 3 may accept a reset of the current teaching point and repeat from step S22.

[0045] In step S27, the processor 31 confirms whether to continue the teaching operation. If the processor 31 decides to continue the teaching operation (Yes in step S27), it sends a command to the robot 2 to move to the next teaching point according to the instructions from the operating device 5 (step S28), and repeats the process from step S22. On the other hand, if the processor 31 decides not to continue the teaching operation (No in step S27), it terminates the process.

[0046] When the control device 3 receives a timing for cancellation of the monitoring process during the teaching process shown in Figure 7, it operates the robot 2 according to the teaching content, but does not execute the monitoring process at the time the cancellation was received. At the time the cancellation is received, the control device 3 may, for example, emit a warning sound to indicate that cancellation is in progress, or reduce the operating speed of the robot 2.

[0047] In the example shown in Figure 7, the control device 3 notifies the user when the robot 2 passes through the monitoring range for each teaching point. However, it may also notify the user of the timing when the robot 2 passes through the monitoring range after all teaching points have been set. For example, when the control device 3 receives instructions from the operating device 5 to play back all teaching points, it executes steps S22 and S23 in Figure 7 in a fixed processing cycle and stores the timing when the robot 2 passes through the monitoring range. Then, when the playback of all teaching points is complete, the control device 3 transmits the timing when the robot 2 passes through the monitoring range to the operating device 5. The operating device 5 presents the timing when the robot 2 passes through the monitoring range to the user and accepts the timing to cancel the monitoring process or to reset the teaching points.

[0048] As described above, the robot system 1 of the embodiment of the present invention comprises a robot 2, a control device 3, and sensors 4a and 4b that measure the distance to an object with a fixed range in a substantially horizontal direction as the monitoring range. The control device 3 acquires the current measurement values ​​from sensors 4a and 4b, calculates the current arm position of the robot 2, and projects a point based on the current measurement value and a figure based on the current arm position onto a projection plane in a direction 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 value and the figure based on the current arm position is below a threshold, and if it is below the threshold, it executes a monitoring process to stop the operation of the robot 2. This makes it possible to efficiently avoid contact between people and the robot 2 without having to perform complex preparations when changing the operation of the robot 2. In particular, even if a person enters the range of movement of the robot 2, as long as they are away from the robot 2, the operation of the robot 2 will not be stopped, thus preventing a decrease in the operating rate of the robot 2.

[0049] Furthermore, the control device 3 pre-stores the initial measurement values ​​of sensors 4a and 4b in the initial state before the robot 2 starts moving. 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. If there is a difference, it determines whether the distance between the point based on the current measurement value and the figure based on the arm position is below a threshold. If it is below the threshold, it stops the robot 2 from moving. The initial state storage process to pre-store the initial measurement values ​​needs to be performed each time the environment around the robot 2 is changed, but since the control device 3 performs this automatically, the user does not have to perform complex preparations in advance, thus reducing the burden on the user.

[0050] Furthermore, in the monitoring process, the control device 3 releases the stop on the robot 2's movement if, for all monitoring ranges, there is no difference between the current measurement value and the initial measurement value, 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. This allows the control device 3 to automatically restart the robot 2's movement even if it has stopped, once the person has moved away from the robot 2.

[0051] Furthermore, the robot system 1 is further equipped with an operating device 5 used by the user 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 during 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 within the monitoring range of the laser beams of sensors 4a and 4b, and accepts whether or not to cancel the monitoring process. This allows the user to teach the robot 2 to move to a position that blocks the laser beams of sensors 4a and 4b without stopping the robot 2's movement, thus increasing the degree of freedom in teaching the robot 2.

[0052] Furthermore, 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 proximity / contact monitoring processes using other non-contact sensors, etc. This allows the control device 3 to detect situations that would otherwise be blind spots and undetectable with a single process, by having multiple processes complement each other.

[0053] Preferred embodiments of the robot system and the like according to the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications and alterations can be conceived within the scope of the technical idea disclosed herein, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0054] 1…Robot system 2…Robot 3…Control device 4a, 4b... Sensors 5……Operating device 7……Projection plane 22……Projection plane 44a, 44b... Monitoring range Ca, Cb... distance to the object E...Figure based on current arm position Fa, Fb... Points based on current measurements Ga, Gb... Distance between a point based on the current measurement and a 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 with a fixed range in a roughly horizontal direction as its monitoring range, Equipped with, The control device acquires the current measurement value from the sensor, 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 below a threshold, and if it is below the threshold, executes a monitoring process to stop the robot's operation. A robotic system characterized by the following features.

2. The control device stores in advance the initial measurement value of the sensor in the initial state before the robot starts moving, and in the monitoring process, it determines whether there is a difference between the current measurement value and the initial measurement value. If there is a difference, it determines whether the distance between the point based on the current measurement value and the figure based on the current arm position is below a threshold, and if it is below the threshold, it stops the robot's movement. The robot system according to feature 1.

3. The control device, in the monitoring process, releases the stop of the robot's movement if, for all of the monitoring range, there is no difference between the current measurement value and the initial measurement value, 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. The robot system according to claim 2, characterized in that it is the same as described in claim 2.

4. The system further comprises an operating device used by the user to operate the robot, The control device determines whether there is a difference between the current measurement value and the initial measurement value during the robot teaching process, and if there is a difference, it notifies the operating device that the robot is passing through the monitoring range and accepts whether or not to cancel the monitoring process. The robot system according to claim 2, characterized in that it is the same as described in claim 2.

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