Robotic system
By measuring the distance to an object with sensors and storing the initial value, and then using the control device to determine the current difference, the problem of complex risk assessment in existing technologies is solved, and the robot's movements are made more efficient by avoiding human contact and improving operational efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NACHI FUJIKOSHI CORP
- Filing Date
- 2025-11-24
- Publication Date
- 2026-08-04
AI Technical Summary
Existing technologies require complex risk assessments and detection zone settings when using safety laser scanners to avoid human-robot contact, and the robot's operational rate is low.
Sensors are used to measure the distance to objects within a roughly horizontal range. The control device stores the initial measurement values and monitors them when the robot starts. It determines the difference between the current measurement value and the initial value and decides whether to stop the robot's movement based on a threshold.
No complicated preparations are required when changing robot actions, effectively avoiding human-robot contact and improving robot operating efficiency.
Smart Images
Figure CN122500796A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a robot system that has the function of avoiding contact between humans and robots. Background Technology
[0002] Previously, collaborative robots have been an example of robots that share space with workers and can be used without safety barriers. The control device of a collaborative robot has the function of detecting external forces such as collisions with workers during collaborative operation and stopping the robot safely. For example, Patent Document 1 discloses a coordinated industrial robot that includes: a contact force detection unit that detects the contact force applied to the robot when a worker comes into contact with the robot; and a contact force monitoring unit that stops the robot or causes the robot to retreat in a direction that reduces the contact force if the contact force exceeds a predetermined threshold.
[0003] Furthermore, even in robot systems that do not detect external forces acting on the robot, operation without safety barriers is sometimes possible if safety devices such as safety laser scanners are used. Generally, a safety laser scanner is a safety device that detects whether an operator has entered a pre-defined detection area. In conventional robot systems using safety laser scanners, the robot stops when the robot's control device receives a signal from the safety laser scanner—that is, when a person enters the detection area. This allows the robot to be safely stopped before the operator comes into contact with it.
[0004] Existing technical documents
[0005] Patent documents
[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-199174 Summary of the Invention
[0007] The problem that the invention aims to solve
[0008] However, when using conventional methods with safety laser scanners to avoid human-robot contact, thorough risk assessments and detection zone settings are required based on the robot's movements. Changing the robot's movements necessitates repeating risk assessments and detection zone settings, increasing preparation time.
[0009] Furthermore, when using conventional methods with safety laser scanners to avoid human-robot contact, it is necessary to establish a detection zone covering all locations where the robotic arm might move or enter. Moreover, if a person enters the detection zone, the robot will stop even if the person is far away, thus reducing the robot's operational efficiency.
[0010] The present invention was made in view of the foregoing circumstances, and its object is to provide a robot system that can effectively avoid human-robot contact without complex prior preparation when changing the robot's actions.
[0011] Methods for solving problems
[0012] The present invention, intended to achieve the aforementioned objectives, is a robot system comprising: a robot having a robotic arm; a control device for controlling the robot's movements; and a sensor for measuring the distance to an object within a generally horizontal range as a monitoring range. The control device pre-stores initial measurement values of the sensor in an initial state prior to initiating the robot's movements. During robot startup, a monitoring process is executed cyclically. 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, calculates the current position of the robotic arm if a difference exists, projects a point based on the current measurement value and a graph based on the current robotic arm position onto a projection plane orthogonal to the vertical direction, determines whether the distance between the point based on the current measurement value and the graph based on the current robotic arm position is below a threshold, and stops the robot's movements if the distance is below the threshold.
[0013] Alternatively, the sensor measures the distance to the object by changing the angle within the monitoring range, the control device pre-stores the initial measurement value for each angle, and in the monitoring process, the control device obtains 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.
[0014] Alternatively, during the monitoring process, if, within all the monitoring ranges, there is no difference between the current measured value and the initial measured value, or if the distance between the point based on the current measured value and the graph based on the current robotic arm position is greater than a threshold, the control device may release the robot's movement from stopping.
[0015] Alternatively, the robot system may also include an operating device for a user to operate the robot. During the robot's teaching process, the control device determines whether there is a difference between the current measured value and the initial measured value. If there is a difference, the control device notifies the operating device that the robot has passed within the monitoring range and asks whether to cancel the monitoring process.
[0016] Invention Effects
[0017] This invention provides a robot system that can effectively avoid human-robot contact without complex prior preparation when changing the robot's actions. Attached Figure Description
[0018] Figure 1 This is a diagram showing the overall structure of the robot system involved in this embodiment.
[0019] Figure 2 It is shown Figure 1 A block diagram of the hardware structure of the robot system.
[0020] Figure 3 It shows through Figure 1 A flowchart illustrating an example of the initial state storage and processing flow implemented by the control device.
[0021] Figure 4 It is used for explanation Figure 3 The initial state storage process is shown in the top view.
[0022] Figure 5 It shows through Figure 1 A flowchart illustrating an example of the monitoring and processing flow implemented by the control device.
[0023] Figure 6 It is used for explanation Figure 5 The diagram shows the processing step S15.
[0024] Figure 7 It shows through Figure 1 A flowchart illustrating an example of the teaching process implemented by the control device.
[0025] Explanation of reference numerals in the attached figures
[0026] 1………Robot System
[0027] 2………robot
[0028] 3… Control device
[0029] 4a, 4b... Sensors
[0030] 5………operating device
[0031] 7………Projection Plane
[0032] 22………Projection Plane
[0033] 44a, 44b... Surveillance range
[0034] The distances from Ca, Cb, etc. to the object
[0035] E…Graphics based on the current position of the robotic arm
[0036] Fa, Fb... points based on the current measured values
[0037] Ga, Gb... Distance between a point based on the current measurement and a graph based on the current position of the robotic arm. Detailed Implementation
[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a diagram illustrating the overall structure of the robot system involved in this embodiment. (As shown...) Figure 1 As shown, the robot system 1 includes: a robot 2; a control device 3 that controls the movements of the robot 2; and sensors 4a and 4b that measure information indicating the distance from its own position to an object. The object includes a person. Additionally, the robot system 1 may also include an operating device 5 for a user to operate the robot 2. Figure 1 In the example shown, a roughly rectangular worktable 6 is positioned in front of the robot 2. The worktable 6 is a platform on which workpieces (not shown) are placed.
[0039] Figure 1 The Z-axis represents the vertical direction. The X-axis and Y-axis are orthogonal to the Z-axis and to each other. That is, the plane formed by the X-axis and Y-axis is orthogonal to the vertical direction. Robot 2 is positioned on a plane that is approximately orthogonal to the vertical direction.
[0040] Robot 2 is, for example, a vertical multi-joint robot with six joints. Robot 2 includes: a base 21, which is disposed on the ground, etc.; a robotic arm 22, which is connected to the base 21; and a tool 23, which is mounted on the front end of the robotic arm 22. The robotic arm 22 has multiple joints, which are constituted by a linkage mechanism with multiple links. Each joint connects a pair of adjacent links, which are driven by a power mechanism (motor, reducer, bearing, gear, etc.) to cause the pair of links to rotate relative to each other. The tool 23 is, for example, a gripper capable of holding a workpiece, etc. It should be noted that embodiments of the present invention are applicable regardless of the number of joints in robot 2 or the type of tool 23.
[0041] It should be noted that the control device 3 can be installed inside or outside the robot 2. Furthermore, there can be one or multiple control devices 3. In the case of multiple devices, the control devices 3 are connected in a manner that allows them to communicate with each other. Figure 1 In the example shown, the control device 3 is located outside the robot 2, and there is one unit.
[0042] Sensors 4a and 4b illuminate a certain range in a roughly horizontal direction (roughly parallel to the plane where robot 2 is located) with a laser, and measure the distance to the object at each laser illumination angle. Sensors 4a and 4b are, for example, safety devices such as safety laser scanners. Sensors 4a and 4b project a beam of laser light through a projector, receive the reflected light from the object using a receiver, and measure the time from projection to reception to calculate the distance from their own position to the object. Sensors 4a and 4b can detect the presence of surrounding objects by calculating the distance by gradually changing the angle in a fan-shaped pattern. Figure 1 In the example shown, there are two sensors 4a and 4b, but there could be one or more. Sensors 4a and 4b are, for example, located on the two sides 21a and 21b of the base 21 of the robot 2. It should be noted that the embodiments of the present invention are applicable regardless of the location where the sensors 4a and 4b are installed. Furthermore, sensors 4a and 4b are not limited to security laser scanners; they could also be devices that emit radio waves, such as millimeter-wave radar, as long as they are capable of measuring the distance to an object.
[0043] The operating device 5 is a user-portable terminal, also known as a teach pendant. The operating device 5 is used to teach the robot 2 the work content or to reproduce the content taught to the robot 2. The robot 2 performs actions in teaching mode and reproduction mode according to the instructions of the operating device 5. Operating devices 5 can be button-type (displaying information on a non-touch panel screen and operating via physical buttons) or touch panel-type (using a common tablet terminal with a touch panel screen, a smartphone, or other portable terminal). Figure 2 The operating device 5 is a touch panel type. It should be noted that the embodiments of the present invention are applicable regardless of the type of operating device 5.
[0044] The control device 3 is connected to the robot 2, sensors 4a and 4b, and the operating device 5 in a communicative manner. The control device 3 can be connected to each device via wired communication cables or wirelessly.
[0045] Figure 2 It is shown Figure 1 The diagram shows the hardware structure of the robot system. The robot 2 includes: a motor 24, which rotates for each joint according to instructions from the control device 3; and an encoder 25, which detects the rotation angle of the motor 24 and outputs the axial angle of each joint axis to the control device 3.
[0046] The control device 3 includes 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 similar device, which reads computer programs pre-stored in the auxiliary storage device 33 into the memory 32 and executes multiple commands sequentially. The memory 32 is a volatile memory such as semiconductor memory, a storage device that the processor 31 can directly read and write data to. The auxiliary storage device 33 is a non-transitory storage medium that a computer can read, such as a hard disk drive, solid-state drive, or USB (Universal Serial Bus) memory, which stores computer programs and data. The input / output interface 34 is an external connection device for inputting and outputting signals to the robot 2, sensors 4a and 4b, and the operating device 5.
[0047] The operating device 5 includes a processor 51, a memory 52, an auxiliary storage device 53, a touch panel 54, and an 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 in the control device 3, and therefore their description is omitted. The touch panel 54 is an input device integrated with a display device such as a liquid crystal display, used to display data and accept data input based on touch operations. The input / output interface 55 is an external connection device for inputting and outputting signals to the control device 3, etc. It should be noted that although not explicitly stated in the original text... Figure 2 As shown in the middle figure, the operating device 5 also has an emergency stop switch that instructs the robot 2 to stop in an emergency, and an enable switch that enables the operation of the robot 2.
[0048] The functions of the control device 3 and the operating device 5, in whole or in part, can be constituted by logic circuits or analog circuits. Furthermore, the control device 3 and the operating device 5 can also be configured with various program processing methods using electronic circuits such as FPGAs (Field Programmable Gate Arrays). Additionally, the control device 3 and the operating device 5 may also include, for example, wireless communication devices and speakers. Figure 2 Devices not shown in the diagram.
[0049] Figure 3 It shows through Figure 1 A flowchart illustrating an example of the initial state storage processing flow implemented by the control device. Initial state storage processing involves storing initial measured values of the distances to the object from each illumination angle of the lasers from sensors 4a and 4b in the initial state before the control device 3 initiates the movement of the robot 2. The control device 3 executes this process for each sensor 4a and 4b. Figure 3 The processing is shown.
[0050] like Figure 3 As shown, the processor 31 of the control device 3 sets the initial illumination 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 the initial measurement values have been stored for all illumination angles (step S4). If the initial measurement values have not been stored for all illumination angles (no in step S4), the processor 31 sets the next illumination angle (step S5) and repeats the process from step S2. On the other hand, if the initial measurement values have been stored for all illumination angles (yes in step S4), the processor 31 ends the process.
[0051] Figure 4 It is used for explanation Figure 3 A top-down view of the initial state storage process. Figure 4 The robotic arm 22, tool 23, control device 3, and operating device 5 of robot 2 are not shown in the diagram. Only the base 21, sensors 4a and 4b, and worktable 6 of robot 2 are shown. The maximum illumination angle range of sensors 4a and 4b is, for example, 270 degrees. Sensors 4a and 4b are disposed on the two sides 21a and 21b of the base 21, thus enabling them to monitor approximately the entire surroundings of robot 2. It should be noted that even when sensors 4a and 4b are disposed at a position away from robot 2, it is also possible to monitor approximately the entire surroundings of robot 2 by displacing two sensors 4a and 4b opposite each other across robot 2.
[0052] The illumination angles of sensors 4a and 4b are the angles α and β formed by the reference directions 41a and 41b and the laser illumination directions 42a and 42b. The monitoring ranges 44a and 44b of sensors 4a and 4b are determined by the monitoring distance (within the maximum illumination distance) and the monitoring angle range (within the maximum illumination angle range) set by sensors 4a and 4b. The measured values Ca and Cb of sensors 4a and 4b are the distances from the laser illumination position to the locations 43a and 43b where the laser is reflected by the object. Figure 4 The measured values Ca and Cb of sensors 4a and 4b shown are the distances to the worktable 6. When there are no objects within the monitoring distance, the measured values Ca and Cb of sensors 4a and 4b become the same as the monitoring distance. It should be noted that, in practice, the monitoring ranges 44a and 44b are widened by a predetermined emission angle in the vertical direction along the Z-axis, centered on the laser emission section of sensors 4a and 4b.
[0053] Control device 3 via Figure 3The initial measurement values of sensors 4a and 4b are pre-stored in the initial state before the robot 2 begins its movement, and are processed accordingly. The processor 31 of the control device 3, for example, stores the measurement values Ca and Cb in polar coordinates (α, Ca) and (β, Cb) in the auxiliary storage device 33. Although... Figure 3 The processing needs to be done every time the environment around robot 2 changes, but since the control device 3 handles it automatically, the user does not need to do complicated preparations in advance.
[0054] Figure 5 It shows through Figure 1 A flowchart illustrating an example of the monitoring and processing flow implemented by the control device 3. During the startup of robot 2, the control device 3 executes a specific processing cycle. Figure 5 Monitoring and processing. Control device 3 is used to perform... Figure 5 The monitoring and processing of the robot 2 involves pre-storing the link parameters of the robot 2, the shape information of the robotic arm 22 (dimensions, weight, etc. of each part), and the placement positions of sensors 4a and 4b in the auxiliary storage device 33. The link parameters include the distance between links, the link torsion angle, and the link length, for example, using the Denavit-Hartenberg notation (DH method) DH parameters. The placement positions of sensors 4a and 4b are, for example, set as coordinates in the robot coordinate system (Xr, Yr, Zr) of the robot 2. The processor 31 of the control device 3 executes... Figure 5 Before monitoring and processing, these data are read from the auxiliary storage device 33 into the memory 32.
[0055] like Figure 5 As shown, the processor 31 of the control device 3 sets the initial illumination angle (step S11). Next, the processor 31 obtains the current measured values of sensors 4a and 4b (step S12) and confirms 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 measured values of sensors 4a and 4b and the initial measured values at the same illumination 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. Through the determination process in step S13, if the robot 2 is only approaching an object that has existed since the initial state (e.g., workbench 6), it is not necessary to stop the robot 2's movement.
[0056] In step S14, the processor 31 obtains the angles of each axis from the robot 2 and performs forward kinematics calculations using the data of each axis angle, link parameters, and the shape of the robotic arm. Furthermore, the processor 31 analytically calculates the positions of various parts of the robot 2 (each joint axis, tool 23, etc.) and the current position of the robotic arm in the robot coordinate system (Xr, Yr, Zr). The current position of the robotic arm is, for example, the position of the tool center point (TCP), which is set as the coordinate center of the front end of the tool 23. Additionally, the current position of the robotic arm is not limited to a single point; besides the TCP position, it may also include the positions of each joint axis.
[0057] Next, the processor 31 confirms whether the distance between the current measurement value in step S13 and the current position of the robotic arm in step S14 is below a threshold (step S15).
[0058] Figure 6 It is used for explanation Figure 5 The diagram shows the processing step S15. Figure 6 The projection plane 7 shown is a plane that is approximately parallel to the plane on which robot 2 is set. More specifically, Figure 6 The projection plane 7 shown is a plane orthogonal to the vertical direction. For example, it is a plane formed by the Xr axis and the Yr axis orthogonal to the Zr axis in the robot coordinate system (Xr, Yr, Zr) of robot 2.
[0059] Da (Xda, Yda) and Db (Xdb, Ydb) represent the points indicating the installation positions of sensors 4a and 4b, respectively. E (Xe, Ye) is the foot of the perpendicular line drawn from the point based on the current robotic arm position in step S14, i.e., the current robotic arm position, to the projection plane 7. Processor 31 converts the current measured values (α, Ca) and (β, Cb) of sensors 4a and 4b in step S13 from polar coordinates to orthogonal 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, processor 31 offsets the coordinates Da (Xa, Ya) and Db (Xb, Yb) representing the installation positions of sensors 4a and 4b by a certain amount from the origin O and projects Fa (Xfa, Yfa) and Fb (Xfa, Xfb).
[0060] Furthermore, the processor 31 calculates the distances Ga and Gb between points Fa (Xfa, Yfa) and Fb (Xfa, Xfb) based on the current measured values and points E (Xe, Ye) based on the current position of the robotic arm, and determines whether they are below the threshold. Figure 6In the example, both objects 8a and 8b are within the movable range of the robotic arm 22 of robot 2. With object 8a, since it is close to the robotic arm, it is necessary to stop the robot 2's movement. On the other hand, with object 8b, since it is far from the robotic arm, it is not necessary to stop the robot 2's movement.
[0061] exist Figure 6 In the example, processor 31 projects a point onto projection plane 7 based on the current position of the robotic arm, but it can also project lines, circles, ellipses, and polygons. For example, processor 31 can also calculate the position of TCP and each joint axis based on the current position of the robotic arm, and project lines connecting TCP and each joint axis, circles, ellipses, and polygons that represent the shape of the robotic arm 22 onto projection plane 7.
[0062] In other words, processor 31 projects a point based on the current measurement value and a graphic based on the current robotic arm position onto projection plane 7, and determines whether the distance between the point based on the current measurement value and the graphic based on the robotic arm position is below a threshold. The graphic based on the robotic arm position includes planar graphics such as points, lines, circles, ellipses, and polygons. The distance is, for example, the shortest Euclidean distance between the point and the graphic.
[0063] Return to Figure 5 The following is an explanation. If the distance between the point based on the current measurement value and the graphic based on the current position of the robotic arm is below a threshold (Yes in step S15), the processor 31 sends a command to the robot 2 to stop its movement (step S16), ending the process. On the other hand, if the distance between the point based on the current measurement value and the graphic based on the current position of the robotic arm is greater than the threshold (No in step S15), the processor 31 proceeds to step S17.
[0064] In step S17, the processor 31 checks whether the processing from steps S12 to S16 has been performed at all illumination angles. If the processing at all illumination angles has not been completed (No in step S17), the processor 31 sets the next illumination angle (step S18) and repeats the processing from step S12. On the other hand, if the processing at all illumination angles has been completed (Yes in step S17), the processor 31 sends a command to the robot 2 to release the action stop (step S19), ending the processing. That is, the processor 31 releases the action stop of the robot 2 if there is no difference between the current measurement value and the initial measurement value at all illumination angles, or if the distance between the point based on the current measurement value and the graphic based on the current position of the robotic arm is greater than a threshold. Thus, if the object and the robot 2 are separated, the control device 3 can automatically restart the action of the robot 2.
[0065] Figure 7 It shows through Figure 1 A flowchart illustrating an example of the teaching process implemented by the control device. Figure 5 During the monitoring process, when robot 2 moves to a position that obstructs the laser beams of sensors 4a and 4b, control device 3 stops robot 2's movement, thus preventing robot 2 from performing the desired action. Therefore, in Figure 7 In the teaching process, if the user's instruction is to move the robot 2 towards the position of the lasers blocking the sensors 4a and 4b, the control device 3 receives a confirmation message via the operating device 5 indicating whether to proceed. Figure 5 The monitoring process was cancelled.
[0066] like Figure 7 As shown, the processor 31 of the control device 3 sends a command to the robot 2 to move towards the initial teaching point according to the instructions from the operating device 5 (step S21). Next, the processor 31 obtains the current measured values of sensors 4a and 4b (step S22) and confirms whether there has been a change from the initial state (step S23). Specifically, the processor 31 and... Figure 5 Similarly, in step S13, it is determined whether there is a difference between the current measured value and the initial measured value of sensors 4a and 4b under the same illumination angle. Processor 31 performs the processing of steps S22 and S23 for all illumination angles. Furthermore, if there is a difference between the current measured value and the initial measured value at any illumination angle (yes in step S23), processor 31 proceeds to step S24; if there is no difference at any illumination angle (no in step S23), it proceeds to step S27.
[0067] In step S24, the processor 31 notifies the operating device 5 that the robot 2 has passed within the monitoring range (step S24). Conversely, the processor 51 of the operating device 5 displays the indication that the robot 2 has passed within the monitoring range on the touch panel 54. Then, the processor 51 receives an instruction from the user via the touch panel 54 to cancel the monitoring process.
[0068] Processor 31 checks whether there is an indication to cancel the monitoring process (step S25). If there is an indication to cancel (yes in step S25), processor 31 stores the timing of the cancellation of the monitoring process (step S26) and proceeds to step S27. For example, processor 31 stores the movement action from the previous teaching point to the current teaching point as the timing of the cancellation of the monitoring process in auxiliary storage device 33. If there is no indication to cancel (no in step S25), control device 3 does nothing and proceeds to step S27. Alternatively, control device 3 may accept the resetting of the current teaching point before proceeding to step S27, repeating the process from step S22.
[0069] In step S27, the processor 31 determines whether to continue the teaching operation. If the teaching operation continues (Yes in step S27), the processor 31 sends a command to the robot 2 to move to the next teaching point according to the instruction from the operating device 5 (step S28), and repeats the process from step S22. On the other hand, if the teaching operation does not continue (No in step S27), the processor 31 ends the process.
[0070] Control device 3 receives Figure 7 In the event of cancellation of monitoring processing during teaching, when robot 2 is being instructed to perform actions according to the teaching content, monitoring processing is not executed upon receiving cancellation. Upon receiving cancellation, control device 3 may, for example, issue a warning sound indicating cancellation, or reduce the movement speed of robot 2.
[0071] exist Figure 7 In the example, control device 3 notifies robot 2 to pass within the monitoring range for each teach point, but it can also notify robot 2 of the timing of passing within the monitoring range after all teach points have been set. For example, when control device 3 receives the reproduction instructions for all teach points from operating device 5, it executes a certain processing cycle. Figure 7 In steps S22 and S23, the timing of robot 2 passing within the monitoring range is stored. Furthermore, when the reproduction of all taught points is complete, the control device 3 sends the timing of robot 2 passing within the monitoring range to the operation device 5. The operation device 5 then prompts the user with the timing of robot 2 passing within the monitoring range, the timing of canceling the monitoring process, and the resetting of the taught points.
[0072] The robot system 1 according to the embodiment of the present invention includes: a robot 2; a control device 3; and sensors 4a and 4b, which measure the distance to an object by using a certain range in the approximately horizontal direction as a monitoring range. The control device 3 acquires the current measurement values of the sensors 4a and 4b, calculates the current position of the robot 2's robotic arm, and projects a point based on the current measurement value and a pattern based on the current robotic arm position onto a projection plane in a direction approximately parallel to a plane orthogonal to the vertical direction. Furthermore, the control device 3 determines whether the distance between the point based on the current measurement value and the pattern based on the current robotic arm position is below a threshold value. If it is below the threshold value, it performs monitoring processing to stop the robot 2's movement. Thus, when changing the robot 2's movement, contact between a person and the robot 2 can be effectively avoided without complex prior preparation. In particular, even if a person enters the robot 2's movable range, the robot 2's movement will not stop as long as the person moves away from the robot 2, thereby preventing a decrease in the robot 2's operating efficiency.
[0073] Furthermore, the control device 3 pre-stores the initial measurement values of sensors 4a and 4b in the initial state before the robot 2 begins its movement. In its monitoring process, the control device 3 determines whether there is a difference between the current measurement value and the initial measurement value. If a difference exists, it determines whether the distance between the point based on the current measurement value and the graphic based on the robot arm's position is below a threshold. If it is below the threshold, the robot 2's movement is stopped. While the initial state storage process for pre-storing the initial measurement values requires recurrence every time the robot 2's surrounding environment changes, the control device 3 performs this automatically, reducing the user's burden by eliminating the need for complex pre-preparation.
[0074] Furthermore, during monitoring, if the current measured value is not different from the initial measured value within all monitoring ranges, or if the distance between the point based on the current measured value and the graphic based on the robot arm's position is greater than a threshold, the control device 3 will release the stop of the robot 2's movement. Therefore, even if the control device 3 stops the robot 2's movement, it can automatically restart the robot 2's movement if a person moves away from the robot 2.
[0075] In addition, the robot system 1 also includes an operating device 5 for user operation of the robot 2. During the teaching process of the robot 2, the control device 3 determines whether there is a difference between the current measured value and the initial measured value. If a difference exists, the control device 3 notifies the operating device 5 that the robot 2 has passed within the monitoring range of the lasers from sensors 4a and 4b, and requests cancellation of the monitoring process. Therefore, even if the user teaches the robot 2 to move towards a position that blocks the lasers from sensors 4a and 4b, the robot 2's movement does not stop, increasing the degree of freedom in the teaching content of the robot 2.
[0076] It should be noted that the control device 3 can also be used in conjunction with the monitoring process in the embodiments of the present invention, as well as other proximity / contact monitoring processes using non-contact sensors, etc. Therefore, even for situations that would be undetectable in a single process, the control device 3 can be detected by multiple complementary processes.
[0077] The preferred embodiments of the robot system and the like of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to these examples. It is obvious that those skilled in the art will be able to conceive of various modifications or alterations within the scope of the technical concept disclosed in this application, and it should be understood that these modifications and alterations naturally also fall within the technical scope of the present invention.
Claims
1. A robot system, characterized in that, The robot system has the following features: A robot, which has a robotic arm; Control device, which controls the actions of the robot; and A sensor that uses a roughly horizontal range as its monitoring area to determine the distance to an object. The control device pre-stores the initial measurement values of the sensors in the initial state before the robot's movement begins. During the robot's startup, it performs monitoring processing in a certain processing cycle. In the monitoring process, the control device obtains the current measurement value of the sensor, determines whether there is a difference between the current measurement value and the initial measurement value, calculates the current position of the robot's robotic arm if there is a difference, projects a point based on the current measurement value and a graphic based on the current robotic arm position onto a projection plane orthogonal to the vertical direction, determines whether the distance between the point based on the current measurement value and the graphic based on the current robotic arm position is below a threshold, and stops the robot's movement if it is below the threshold.
2. The robot system according to claim 1, characterized in that, The sensor measures the distance to the object by changing its angle within the monitoring range. The control device pre-stores the initial measured values for each angle. In the monitoring process, the control device obtains 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.
3. The robot system according to claim 1, characterized in that, In the monitoring process, if, within all the monitoring ranges, there is no difference between the current measured value and the initial measured value, or if the distance between the point based on the current measured value and the graph based on the current robotic arm position is greater than a threshold, the control device releases the stop of the robot's movement.
4. The robot system according to claim 1, characterized in that, The robot system also includes an operating device for users to operate the robot. During the robot's teaching process, the control device determines whether there is a difference between the current measurement value and the initial measurement value. If there is a difference, it notifies the operating device that the robot has passed within the monitoring range and asks whether to cancel the monitoring process.