Robot control device

Abstract

A robot control device (50) controlling a robot (10) comprises: an external force detection unit (154) that detects an external force applied to the robot; and a stop control unit (150) that switches, according to a signal indicating a state of the robot or a state of a surrounding environment of the robot, stop control for stopping the robot when the external force of a predetermined value or greater is detected by the external force detection unit.

Description

Technical Field

[0001] Embodiments of the present invention relate to a robot control device.

Background Art

[0002] In a collaborative robot that shares a working space with a human without a safety fence, the robot detects contact with the human and stops to ensure safety. Such a robot generally has a function of detecting an external force and stops the robot when the external force detected when a person touches the robot reaches or exceeds a predetermined threshold. ]>

[0003] Patent Document 1 describes that "as described above, the optimal threshold for external force varies depending on the situation. Therefore, it is desirable to change the threshold while ensuring human safety after determining the situation of the robot and the human." (paragraph 0012), and also describes, as the configuration of the control device of the robot, that "the control device 20 is a digital computer, and when the current position of the robot 10 detected by the position detection unit 11 is within a predetermined area, an external force determination condition inside and outside the area is set as an external force determination condition, and when the current position of the robot 10 is outside the predetermined area, an external force determination condition outside the area is set as an external force determination condition, and includes an external force determination condition setting unit 21." (paragraph 0023).

[0004] Patent Document 2 relates to a human collaborative robot system and describes "a human collaborative robot system in which a robot and a human share a working space, a detection unit that directly or indirectly detects a physical quantity that changes according to a contact force received by the robot when the robot contacts an external environment, and the physical quantity detected by the detection unit is compared with a first threshold and a second threshold larger than the first threshold, respectively, and when the physical quantity is the first threshold and less than the second threshold, the robot is stopped according to a predetermined stop method, and when the physical quantity is greater than or equal to the second threshold, a stop command unit that stops the robot in a shorter time than the predetermined stop method." (Claim 1).

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-077608 [Patent Document 2] Japanese Patent Publication No. 2016-064474 [Overview of the project] [Problems that the invention aims to solve]

[0006] Here, we consider the scenario where a robot is stopped due to contact with a person or object detected by an external force detection function. The tasks performed by robots are diverse, and robots are configured to operate in various work environments. Furthermore, the tasks and work environments of workers collaborating with robots are also diverse. Therefore, when a robot is stopped due to contact with a person or object, a wide range of considerations must be taken into account, from further ensuring safety based on risk assessment to protecting the workpiece the robot is gripping. In cases where a robot is stopped due to contact with a person or object, there is a need for a robot control device that can achieve more appropriate stop control by dynamically switching stop control according to the situation. [Means for solving the problem]

[0007] One aspect of the present disclosure is a robot control device for controlling a robot, comprising: an external force detection unit for detecting an external force acting on the robot; and a stop control unit for switching stop control for stopping the robot when the external force detection unit detects an external force exceeding a predetermined value, in accordance with a signal indicating the state of the environment surrounding the robot. The stop control unit switches the stop control by changing the type and / or set value of a control parameter, which includes at least one of the following: stop time, acceleration, jerk, motor current, shaft torque, and reversal distance. This is a robot control device. [Effects of the Invention]

[0008] With the above configuration, when contact between the robot and the external environment is detected and the robot is stopped, it becomes possible to achieve more appropriate stop control by dynamically switching the stop control according to the situation.

[0009] These and other objects, features, and advantages of the present invention will become even clearer from the detailed description of typical embodiments of the present invention shown in the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the first embodiment. [Figure 2] This figure shows an example of the hardware configuration of a robot control device. [Figure 3] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the second embodiment. [Figure 4] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the third embodiment. [Figure 5] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the fourth embodiment. [Figure 6] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the fifth embodiment. [Figure 7] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the sixth embodiment. [Figure 8] This figure shows the equipment configuration of the robot system and the functional block of the robot control device according to the seventh embodiment. [Modes for carrying out the invention]

[0011] Next, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, similar components or functional parts are given the same reference numerals. For ease of understanding, the scale of these drawings has been appropriately changed. Furthermore, the embodiments shown in the drawings are just one example of how to carry out the present invention, and the present invention is not limited to the illustrated embodiments.

[0012] The following describes robot systems including robot control devices according to the first to seventh embodiments. In each embodiment, when contact between the robot and the external environment (people or objects in the workspace) is detected and the robot is stopped, the robot control device is configured to dynamically switch the control content of the stop control according to signals indicating the state of the robot and the state of the surrounding environment, thereby achieving more appropriate stop control according to the situation.

[0013] First Embodiment Figure 1 shows the equipment configuration of the robot system 100 and the functional blocks of the robot control device 50 according to the first embodiment. The robot system 100 is configured as a collaborative robot system in which a human and a robot share a workspace. As shown in Figure 1, the robot system 100 comprises a robot 10 and a robot control device 50 that controls the robot 10. The robot 10 is, for example, a vertical articulated robot as shown in the figure, but other types of robots may be used. A table 80 for placing workpieces is arranged in the workspace of the robot system 100. The robot 10 works in cooperation with a human to perform predetermined tasks on workpieces placed on the table 80.

[0014] The base 11 of the robot 10 is fixed to the installation floor. The robot 10 can be operated by servo motors (not shown) provided on each joint axis to take a desired position and posture. Further, the robot 10 is provided with a position detection sensor 21 for detecting the position (rotation position) of each joint axis (only some of the position detection sensors are shown in FIG. 1). The position detection sensor 21 is an encoder for detecting the rotation position of the servo motor or an encoder for detecting the rotation position of the joint axis. Signals from each position detection sensor 21 are input to the robot control device 50 and used for calculating the position, posture, and speed of the robot 10 (a predetermined control part of the robot 10).

[0015] The robot 10 can execute a desired operation by an end effector attached to the wrist part at the tip of the arm. The end effector is an external device that can be exchanged according to the application, and for example, it is a hand, a welding gun, a tool, etc. In FIG. 1, an example in which a hand 30 as an example of the end effector is used is shown.

[0016] A force sensor 71 is attached to the lower part of the base 11 of the robot 10. The force sensor 71 is, for example, a six-axis force sensor. The robot control device 50 (external force detection unit 154) can detect an external force (contact force) acting on the robot 10 based on the detection value of the force sensor 71. Note that the configuration may be such that an external force (contact force) acting on the robot 10 is detected using torque sensors arranged on each joint axis (or at least one joint axis) of the robot 10.

[0017] FIG. 2 shows an example of the hardware configuration of the robot control device 50. As shown in FIG. 2, the robot control device 50 may have a configuration as a general computer in which a memory 52 (ROMs, RAMs, non-volatile memories, etc.), an input / output interface 53, an operation unit 54 including various operation switches, etc. are connected to a processor 51 via a bus. Note that the hardware configuration of the robot control device 50 is common to other embodiments described below.

[0018] The robot control device 50 controls the operation of the robot 10 according to a control program or commands from a teaching device (not shown). The robot control device 50 generates a trajectory plan for a predetermined control part (e.g., TCP (Tool Center Point)) of the robot 10 according to the control program and generates commands for each axis of the robot 10 through kinematic calculations. Then, the robot control device 50 can move a predetermined control part of the robot 10 along the planned trajectory by executing servo control for each axis according to the commands for each axis.

[0019] Within the working space where the robot system 100 is installed, a specific area (hereinafter, setting area 90) is set. This setting area 90 is an area where the robot 10 performs work using a tool (hand 30), and is an area that particularly involves the risk of a person being sandwiched between the robot 10 and other objects within the working space. Information (3D position information) of this setting area 90 may be stored in advance in, for example, the memory 52 (non-volatile memory) of the robot control device 50, or may be set by the user via a setting screen (user interface) of a teaching device (not shown) connected to the robot control device 50.

[0020] As will be described below, the robot control device 50 dynamically switches the stop control method to be applied when contact between the robot 10 and the external environment (people and objects within the working space) is detected according to whether the position of the robot 10 is within the setting area 90. Thereby, the robot control device 50 can make the stop control when contact is detected appropriate according to the operating state of the robot 10.

[0021] The functional blocks of the robot control device 50 shown in FIG. 1 are represented by focusing on such a stop control function in the robot control device 50. As shown in FIG. 1, the robot control device 50 includes a robot position calculation unit 151, a stop control unit 150, and an external force detection unit 154.

[0022] The external force detection unit 154 can detect the external force (contact force) acting on the robot 10 by subtracting the weight of the workpiece gripped by the robot 10 and the inertial force generated by the operation of the robot 10 from the detected value output by the force sensor 71. For example, the external force detection unit 154 may be configured to determine that the robot 10 has come into contact with the external environment (person or object) when the detected contact force is above a predetermined threshold.

[0023] The robot position calculation unit 151 calculates the position of the robot 10 (a predetermined movable part) based on position information from position detection sensors 21 placed on each joint axis of the robot 10. For example, the TCP (Tool Center Point) position of the robot 10, or the tool (hand 30) position, may be calculated as the position of the robot 10. This position information is calculated as a value in the world coordinate system set on the base 11 of the robot 10. The robot position calculation unit 151 further calculates whether the position of the robot 10 is within the set area 90 and sends a signal to the stop control unit 150 indicating whether the position of the robot 10 is within the set area 90. In other words, the robot position calculation unit 151 sends a signal to the stop control unit 150 indicating the state of the robot 10.

[0024] For example, the robot position calculation unit 151 may determine whether the robot 10 is located within the set area 90 by comparing the calculated position of the robot 10 (such as the position of the hand 30) with position information indicating the set area 90. Alternatively, the robot position calculation unit 151 may determine whether the robot 10 is located within the set area 90 by virtually placing a model of the robot 10 in the workspace to assume the calculated position and orientation of the robot 10, and then calculating whether the model interferes with the set area 90.

[0025] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop control unit 150 switches the stop control for stopping the robot 10 according to whether the robot 10 is within the set area 90. As a configuration for realizing such a function, the stop control unit 150 includes a stop method determination unit 152 and a stop command unit 153.

[0026] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop method determination unit 152 switches the type and / or set value of the control parameter used for the stop control when the robot 10 is within the set area 90 and when the robot 10 is outside the set area 90. The control parameters used for the stop control may include at least one of the stop time, acceleration, jerk, motor current, axis torque, and reverse distance. Among these control parameters, acceleration, jerk, motor current (the current applied to the motor of each axis), and axis torque are all parameters related to the force for decelerating the robot (each axis).

[0027] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop command unit 153 sends a command to stop the robot 10 to the robot 10 according to the control parameters set by the stop method determination unit 152.

[0028] As an example, the stop method determination unit 152 sets the stop time T1 applied when the robot 10 is within the set area 90 to be shorter than the stop time T2 applied when the robot 10 is outside the set area 90. That is, the stop method determination unit 152 sets the stop time such that T1 < T2. In this case, the stop command unit 153 calculates the acceleration (deceleration) for stopping the robot 10 from the current speed in the stop time T1 (or T2) and executes the deceleration control.

[0029] With the above configuration, when contact between the robot 10 and the external environment is detected and the robot 10 is within the set area 90, the robot 10 can be stopped with a shorter stopping time than when contact between the robot 10 and the external environment is detected and the robot 10 is outside the set area 90, thus reliably preventing situations in which a person is trapped between the robot 10 and other objects within the set area 90. On the other hand, when contact between the robot 10 and the external environment is detected and the robot 10 is outside the set area 90, the robot 10 can be stopped with a longer stopping time than when contact between the robot 10 and the external environment is detected and the robot 10 is within the set area 90, thus preventing excessive load on the robot 10 or workpiece when the robot 10 is stopped outside the set area 90.

[0030] Furthermore, if the robot 10 is within the set area 90, an action may be added to reverse the robot 10 by a predetermined distance after stopping for the above-mentioned stopping time T1. This makes it possible to more reliably avoid situations in which a person is trapped between the robot 10 and other objects.

[0031] As described above, according to the first embodiment, when contact between the robot and the external environment is detected and the robot is stopped, it is possible to dynamically switch the stop control according to the situation and achieve even more appropriate stop control.

[0032] Second Embodiment Figure 3 shows the equipment configuration of the robot system 100B, including the robot control device 50B according to the second embodiment, and the functional blocks of the robot control device 50B. As shown in Figure 3, the robot system 100B includes a robot 10 mounted on a trolley 81 and a robot control device 50B that controls the robot 10. Note that in Figure 2, the same reference numerals are used for the same components as in the functional elements according to the first embodiment.

[0033] A specific area (setting area 91) is defined within the workspace where the robot system 100B is installed. In this example, the setting area 91 is a two-dimensional area set on the floor surface within the workspace, and is the area close to various objects such as columns, surrounding equipment, and structures. In other words, the setting area 91 is the area where there is a risk of the robot 10 (cart 81) interfering with an object, or of a person being trapped between the robot 10 and another object. The setting area 91 may be pre-set in the robot control device 50B, or it may be set by the user via the setting screen (user interface) of a teaching device (not shown) connected to the robot control device 50B.

[0034] As described below, the robot control device 50B is configured to dynamically switch the stop control when contact between the robot 10 and the external environment is detected, depending on whether the robot 10 mounted on the trolley 81 is in a set area 91 set within the work space.

[0035] The functional blocks of the robot control device 50B shown in Figure 3 are represented focusing on the stop control function of the robot control device 50B. The robot control device 50B includes a robot position calculation unit 251, a stop control unit 250, and an external force detection unit 154.

[0036] The external force detection unit 154 detects contact between the robot 10 and the external environment based on the detection value of the force sensor 71.

[0037] The robot position calculation unit 251 detects the position of the trolley 81 (for example, the center position of the trolley 81) based on signals from position detection sensors 22 located on the trolley 81, and uses the detected position of the trolley 81 as the position of the robot 10. The position detection sensors 22 located on the trolley 81 are, for example, sensors that output a vehicle speed pulse of the trolley 81, or acceleration sensors, gyro sensors, etc., for detecting position. The robot position calculation unit 251 may also register the position of the robot 10 (trolley 81) on the map data of the workspace and constantly monitor the position of the robot 10 (trolley 81) on the map data using signals from the position detection sensors 22. Furthermore, the robot position calculation unit 251 calculates whether the position of the robot 10 is within the set area 91 and sends a signal to the stop control unit 250 indicating whether the position of the robot 10 is within the set area 91. That is, the robot position calculation unit 251 sends a signal to the stop control unit 250 indicating the state of the robot 10.

[0038] For example, the robot position calculation unit 251 may determine whether or not the robot 10 is located within the designated area 91 by comparing the position of the robot 10 with position information indicating the designated area 91. Alternatively, the robot position calculation unit 251 may determine whether or not the robot 10 is located within the designated area 91 by virtually placing a model of the robot 10 (including a model of the trolley 81) at the position of the robot 10 and calculating whether or not the model is located within the designated area 91.

[0039] The stop control unit 250 switches the stop control for stopping the robot 10 when contact between the robot 10 and the external environment is detected by the external force detection unit 154, depending on whether the robot 10 is within the set area 91 or not. To realize this function, the stop control unit 250 has a stop method determination unit 252 and a stop command unit 153.

[0040] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop method determination unit 252 switches the type and / or set value of the control parameter used for stop control between the case where the robot 10 is within the set area 91 and the case where the robot 10 is outside the set area 91. The control parameter used for stop control may include at least one of stop time, acceleration, jerk, motor current, shaft torque, and reverse distance.

[0041] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop command unit 153 sends a command to stop the robot 10 to the robot 10 according to the control parameter set by the stop method determination unit 252.

[0042] As an example, the stop method determination unit 252 sets the stop time T21 applicable when the robot 10 (trolley 81) is within the set area 91 to be shorter than the stop time T22 applicable when the robot 10 (trolley 81) is outside the set area 91. That is, the stop method determination unit 252 sets the stop time so that T21 < T22. In this case, the stop command unit 153 obtains the acceleration (deceleration) for stopping the robot 10 from the current speed within the stop time T21 (or T22) and executes deceleration control.

[0043] According to the above configuration, when the robot 10 is within the set area 91 when the contact between the robot 10 and the external environment is detected, the robot 10 can be stopped in a shorter stop time than when the robot 10 is outside the set area 91 when the contact between the robot 10 and the external environment is detected, and it is possible to surely avoid a situation where a person is sandwiched between the robot 10 and another object within the set area 91. On the other hand, when the robot 10 is outside the set area 91 when the contact between the robot 10 and the external environment is detected, the robot 10 can be stopped in a longer stop time than when the robot 10 is within the set area 91 when the contact between the robot 10 and the external environment is detected, and it is possible to avoid an excessive load being applied to the robot 10, the workpiece, etc. when stopping the robot 10 outside the set area 91.

[0044] Furthermore, if the robot 10 is within the designated area 91, an action to reverse the robot 10 after stopping at the above-mentioned stopping time T21 may be added. This makes it even more reliable to avoid situations in which a person is trapped between the robot 10 and other objects.

[0045] Third Embodiment Figure 4 shows the equipment configuration of the robot system 100C, including the robot control device 50C according to the third embodiment, and the functional blocks of the robot control device 50C. As shown in Figure 4, the robot system 100C includes a robot 10 and a robot control device 50C that controls the robot 10. The robot 10 is fixed to the installation floor.

[0046] As described below, the robot control device 50C is configured to dynamically switch stop control when contact between the robot 10 and the external environment is detected, according to the speed of the robot 10 (a predetermined movable part).

[0047] The functional blocks of the robot control device 50C shown in Figure 4 are represented focusing on the stop control function of the robot control device 50C. The robot control device 50C has a speed calculation unit 351, a stop control unit 350, and an external force detection unit 154.

[0048] The external force detection unit 154 detects contact between the robot 10 and the external environment based on the detection value of the force sensor 71.

[0049] The speed calculation unit 351 calculates the speed of the robot 10 (the speed of a predetermined movable part of the robot 10) based on position information from position detection sensors 21 arranged at each joint axis of the robot 10. In this embodiment, the speed calculation unit 351 calculates the speed of a tool (hand 30) attached to the tip of the arm of the robot 10. The speed calculation unit 351 determines whether the speed of the tool is above a predetermined speed value and sends a signal to the stop control unit 350 indicating whether the speed of the tool is above the predetermined speed. That is, the speed calculation unit 351 sends a signal to the stop control unit 350 indicating the state of the robot 10.

[0050] The stop control unit 350 switches the stop control for stopping the robot 10 when contact between the robot 10 and the external environment is detected by the external force detection unit 154, depending on whether the speed of the tool is above a predetermined speed value. To realize this function, the stop control unit 350 has a stop method determination unit 352 and a stop command unit 153.

[0051] The stopping method determination unit 352 switches the type and / or set value of the control parameters used for stopping control when the external force detection unit 154 detects contact between the robot 10 and the external environment, depending on whether the tool speed is above a predetermined speed value or below a predetermined speed value. The control parameters used for stopping control may include at least one of the following: stopping time, acceleration, jerk, motor current, axial torque, and reversal distance.

[0052] The stop command unit 153, upon detection of contact between the robot 10 and the external environment by the external force detection unit 154, sends a command to the robot 10 to stop it according to the control parameters set by the stop method determination unit 352.

[0053] As an example, the stopping method determination unit 352 sets the stopping time T31, which is applied when the tool speed is above a predetermined speed value, to be longer than the stopping time T32, which is applied when the tool speed is below a predetermined speed value. That is, the stopping method determination unit 352 sets the stopping times such that T31 > T32. In this case, the stopping command unit 153 calculates the acceleration (deceleration) required to stop the robot 10 from its current speed at the stopping time T31 (or T32) and performs deceleration control.

[0054] The predetermined speed value mentioned above should be determined by considering factors such as the extent to which the load on the workpiece gripped by the hand 30 should be reduced. For example, if there are circumstances that require further reduction of the load on the workpiece, the predetermined speed value may be set to an even lower value.

[0055] With the above configuration, when contact between the robot 10 and the external environment is detected and the tool speed is above a predetermined speed, the robot 10 can be stopped slowly, thus avoiding excessive load being placed on the robot 10 or the workpiece it is gripping when it stops.

[0056] Fourth Embodiment Figure 5 shows the equipment configuration of the robot system 100D, including the robot control device 50D according to the fourth embodiment, and the functional blocks of the robot control device 50D. As shown in Figure 4, the robot system 100C includes a robot 10 and a robot control device 50C that controls the robot 10. The robot 10 is fixed to the installation floor.

[0057] In the robot system 100D, a contact detection sensor 401 is attached to a specific part of the robot 10 to detect contact between the contact detection sensor 401 and a person or object. The robot control device 50D dynamically switches the stop control when contact between the robot 10 and the external environment is detected, in response to the detection signal from the contact detection sensor 401.

[0058] The functional blocks of the robot control device 50D shown in Figure 5 are represented focusing on the stop control function of the robot control device 50D. The robot control device 50D comprises a signal input unit 451, a stop control unit 450, and an external force detection unit 154.

[0059] The signal input unit 451 receives a signal from the contact detection sensor 401. The signal from the contact detection sensor 401 is, for example, a signal that turns on when contact is detected. The contact detection sensor 401 is installed, for example, in a part of the robot 10 where it is particularly undesirable for a person to touch it. In other words, in this embodiment, the stop control unit 450 receives a signal indicating the surrounding environment of the robot 10 via the signal input unit 451.

[0060] In this example, the contact detection sensor 401 is mounted near the tool (at the tip of the arm). The contact detection sensor 401 may be a mechanical switch that turns on when pressed, a touch sensor, a sensor that detects pressure from an object, etc. Multiple contact detection sensors 401 may be placed to ensure more reliable contact detection.

[0061] The external force detection unit 154 detects contact between the robot 10 and the external environment based on the detection value of the force sensor 71.

[0062] The stop control unit 450 switches the stop control for stopping the robot 10 when contact between the robot 10 and the external environment is detected by the external force detection unit 154, depending on whether or not a person (or other object) is touching the contact detection sensor 401. To realize this function, the stop control unit 450 has a stop method determination unit 452 and a stop command unit 153.

[0063] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop method determination unit 452 switches the type and / or set value of the control parameter used for stop control between the case where a person (or another object) touches the contact detection sensor 401 and the case where a person (or another object) does not touch the contact detection sensor 401. The control parameter used for stop control may include at least one of stop time, acceleration, jerk, motor current, shaft torque, and reverse distance.

[0064] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop command unit 153 sends a command to stop the robot 10 to the robot 10 according to the control parameter set by the stop method determination unit 452.

[0065] As an example, the stop method determination unit 452 sets the stop time T41 applied when the contact is detected by the contact detection sensor 401 (when the signal input to the signal input unit 451 is on) to be shorter than the stop time T42 applied when the contact is not detected by the contact detection sensor 401 (when the signal input to the signal input unit 451 is off). That is, the stop method determination unit 452 sets the stop time so that T41 < T42. In this case, the stop command unit 153 obtains the acceleration (deceleration) for stopping the robot 10 from the current speed in the stop time T41 (or T42) and executes deceleration control.

[0066] By setting the stop time in the stop control as described above, for example, when a person touches a part where it is not desired to be touched on the robot 10 (such as the tip of the arm near the tool), the robot 10 can be stopped in a short time, and it is possible to realize stop control that further enhances the safety for people.

[0067] Regarding the fourth embodiment, the following modification examples are also possible. In this modification example, contact detection sensors are attached to a plurality of different positions on the robot 10, and signals from these contact detection sensors are input to the stop control unit 450 (stop method determination unit 452). As an example, assume a case where a first contact detection sensor is attached to the tip of the arm (flange portion) of the robot 10 and a second contact detection sensor is attached to another part of the arm. Assume that the tip of the arm is a location where the user does not want to be touched the most, and the other part of the arm is a location where the user does not want to be touched next. In this case, when the stop time when contact is detected by the first contact detection sensor is T141, the stop time when contact is detected by the second contact detection sensor is T142, and the stop time when no contact is detected by either the first contact detection sensor or the second contact detection sensor is T143, the stop time may be set so that T141 < T142 < T143. With this configuration, the stop time can be set stepwise according to the degree of risk to the user.

[0068] Fifth Embodiment FIG. 6 is a diagram showing the device configuration of a robot system 100E including a robot control device 50E according to the fifth embodiment, and the functional blocks of the robot control device 50E. As shown in FIG. 5, the robot system 100E includes a robot 10 and a robot control device 50E that controls the robot 10. The robot 10 is fixed to the installation floor.

[0069] In this embodiment, a human detection sensor 501 is arranged at a predetermined position in the work space (for example, the base 11 of the robot 10), and it is detected whether the human OP is approaching the robot 10. The robot control device 50E is configured to dynamically switch the stop control when contact between the robot 10 and the external environment is detected according to whether the human OP is approaching the robot 10.

[0070] The functional blocks of the robot control device 50E shown in Figure 6 are represented focusing on the stop control function of the robot control device 50E. The robot control device 50E includes a signal input unit 551, a stop control unit 550, and an external force detection unit 154.

[0071] The signal input unit 551 receives a signal from a human detection sensor 501 that can detect the approach of a human operator (OP). The signal from the human detection sensor 501 is, for example, a signal that turns on when the approach of a human operator (OP) to the robot 10 is detected. In other words, in this embodiment, the stop control unit 550 receives a signal via the signal input unit 551 that indicates the state of the environment surrounding the robot 10.

[0072] As an example, the human detection sensor 501 may output an ON signal when a person OP enters within a predetermined distance from the robot 10. For example, the human detection sensor 501 is a laser rangefinder or laser scanner that measures the distance to an approaching object by emitting or scanning laser light. Such a laser rangefinder or laser scanner may be placed on the base 11 of the robot 10, or it may be installed at a predetermined location in the workspace. Alternatively, the human detection sensor 501 may be a sheet-shaped sensor that outputs a signal when a person steps on it. Alternatively, the human detection sensor 501 may be a sensor consisting of a camera installed in the workspace that acquires an image of the area around the robot 10 and detects the approach of a person to the robot 10 through image processing.

[0073] The external force detection unit 154 detects contact between the robot 10 and the external environment based on the detection value of the force sensor 71.

[0074] The stop control unit 550 switches between stopping the robot 10 when contact between the robot 10 and the external environment is detected by the external force detection unit 154, and stopping the robot 10 depending on whether or not the human detection sensor 501 detects the approach of a person to the robot 10. To realize this function, the stop control unit 550 has a stop method determination unit 552 and a stop command unit 153.

[0075] When the contact between the robot 10 and the external environment is detected by the external force detection unit 154, the stop method determination unit 552 switches the type and / or setting value of the control parameter used for stop control between the case where the approach of a person to the robot 10 is detected by the human sensing sensor 501 and the case where the approach of a person to the robot 10 is not detected by the human sensing sensor 501. The control parameter used for stop control may include at least one of stop time, acceleration, jerk, motor current, shaft torque, and reverse distance.

[0076] In response to the detection of the contact between the robot 10 and the external environment by the external force detection unit 154, the stop command unit 153 sends a command to stop the robot 10 to the robot 10 according to the control parameter set by the stop method determination unit 552.

[0077] As an example, the stop method determination unit 552 sets the stop time T51 applied when the approach of the person OP to the robot 10 is detected by the human sensing sensor 501 to be shorter than the stop time T52 applied when the approach of the person OP to the robot 10 is not detected by the human sensing sensor 501. That is, the stop method determination unit 552 sets the stop time so that T51 < T52. In this case, the stop command unit 153 obtains the acceleration (deceleration) for stopping the robot 10 from the current speed in the stop time T51 (or T52) and executes deceleration control.

[0078] In a situation where a person is approaching the robot 10, the risk that the person will sway to a dangerous place such as not only the tip of the robot 10 but also the arm body part of the robot 10 increases. In this regard, by performing the above stop control, in a situation where a person is approaching the robot 10, it is possible to stop the robot 10 in a short time and further enhance the safety for the person.

[0079] Sixth Embodiment Figure 7 shows the equipment configuration of a robot system 100F including a robot control device 50F according to the sixth embodiment, and the functional blocks of the robot control device 50F. As shown in Figure 7, the robot system 100F includes a robot 10 and a robot control device 50F that controls the robot 10. The robot 10 is fixed to the installation floor.

[0080] In this embodiment, the robot control device 50F is configured to dynamically switch stop control when contact between the robot 10 and the external environment is detected, based on a signal indicating the operating state (open / closed state) of the hand 30, which is mounted on the robot 10 as an end effector.

[0081] The functional blocks of the robot control device 50F shown in Figure 7 are represented focusing on the stop control function of the robot control device 50F. The robot control device 50F has a signal input unit 651, a stop control unit 650, and an external force detection unit 154.

[0082] The signal input unit 651 receives a signal from the hand 30 indicating its operating status. For example, the signal from the hand 30 is an ON signal when the hand is operating and closed (when the hand 30 is gripping the workpiece W). In other words, in this embodiment, the stop control unit 650 receives a signal indicating the status of the robot 10 via the signal input unit 651.

[0083] The external force detection unit 154 detects contact between the robot 10 and the external environment based on the detection value of the force sensor 71.

[0084] The stop control unit 650 switches the stop control for stopping the robot 10 when the external force detection unit 154 detects contact between the robot 10 and the external environment, depending on whether the hand 30 is closed or not (whether the hand 30 is gripping the workpiece W or not). To realize this function, the stop control unit 650 has a stop method determination unit 652 and a stop command unit 153.

[0085] The stopping method determination unit 652 switches the type and / or set value of the control parameters used for stopping control when the external force detection unit 154 detects contact between the robot 10 and the external environment, depending on whether the hand 30 is gripping the workpiece W or not. The control parameters used for stopping control may include at least one of the following: stopping time, acceleration, jerk, motor current, axial torque, and reversal distance.

[0086] The stop command unit 153, upon detection of contact between the robot 10 and the external environment by the external force detection unit 154, sends a command to the robot 10 to stop it according to the control parameters set by the stop method determination unit 652.

[0087] As an example, the stopping method determination unit 652 sets the acceleration (deceleration) applied to stopping control when the hand 30 is gripping the workpiece W (when the signal input to the signal input unit 651 is ON) to a smaller value than the acceleration (deceleration) applied to stopping control when the hand 30 is not gripping the workpiece W (when the signal input to the signal input unit 651 is OFF). As a result, when the robot 10 is gripping the workpiece W, the robot 10 will stop gently.

[0088] In situations where the robot 10 is gripping a workpiece W and performing work, it is desirable to implement a stop control that prevents excessive load (impact) from being placed on the workpiece W or the robot 10 when contact between the robot 10 and the external environment is detected. Therefore, in this embodiment, acceleration is used as a control parameter applied to the stop control to realize a control that allows the robot 10 to stop gently when the hand 30 is gripping the workpiece W.

[0089] The stopping method determination unit 652 may also set the stopping time T61 applied to the stopping control when the hand 30 is gripping the workpiece W to be longer than the stopping time T62 applied to the stopping control when the hand 30 is not gripping the workpiece W. In this case as well, the robot 10 can be stopped gently when the hand 30 is gripping the workpiece W.

[0090] Seventh Embodiment The first to third embodiments and the sixth embodiment described above can be positioned as configurations that dynamically switch the stop control performed when contact between the robot 10 and the external environment is detected, in accordance with a signal indicating the state of the robot 10. Furthermore, the fourth and fifth embodiments can be positioned as configurations that dynamically switch the stop control performed when contact between the robot 10 and the external environment is detected, in accordance with a signal indicating the state of the environment surrounding the robot 10. Embodiments that integrate the functions described in the first to sixth embodiments are also possible. Below, a robot control device having functions that integrate the functions of the robot control devices according to the first to sixth embodiments will be described.

[0091] Figure 8 is a functional block diagram of the robot system 100G including the robot control device 50G according to the seventh embodiment. In Figure 8, components equivalent to those in the first to sixth embodiments are denoted by the same reference numerals. The equipment configuration of the robot system 100G is equivalent to, for example, the configuration shown in Figure 1, and the various sensors (e.g., human detection sensor 501) are arranged as shown in the corresponding embodiments.

[0092] As shown in Figure 8, the robot system 100G comprises a robot 10 and a robot control device 50G that controls the robot 10. A teaching device 40 may also be connected to the robot control device 50G. The robot control device 50G is configured to have multiple input / output interfaces 53 (Figure 2) that can receive signals from various sensors. Therefore, as shown in Figure 8, the robot control device 50G can be configured to receive signals from the position detection sensor 21 of the robot 10, signals from the position detection sensor 22 located on the trolley 81 if the robot 10 is mounted on the trolley 81, signals from the contact detection sensor 401 attached to the robot 10, signals from the human detection sensor 501, and signals from the hand 30 mounted on the robot 10, depending on the actual equipment configuration of the robot system 100G.

[0093] The teaching device 40 is used to teach the robot 10 or to perform various settings related to teaching. The teaching device 40 may have a configuration similar to a general computer, with memory (ROM, RAM, non-volatile memory, etc.), a display unit, an operation unit, an input / output interface, etc., connected to the processor via a bus.

[0094] The robot control device 50G includes signal input units 451, 551, and 651, a robot position calculation unit 151, a robot position calculation unit 251, a speed calculation unit 351, a stop control unit 750, and an external force detection unit 154. The stop control unit 750 includes a stop method determination unit 752 and a stop command unit 153.

[0095] The signal from position detection sensor 21 is input to the robot position calculation unit 151 and the speed calculation unit 351. The signal from position detection sensor 22 is input to the robot position calculation unit 251. The signal from contact detection sensor 401 is input to the stop method determination unit 752 via signal input unit 451. The signal from human detection sensor 501 is input to the stop method determination unit 752 via signal input unit 551. The signal from hand 30 is input to the stop method determination unit 752 via signal input unit 651.

[0096] The stopping method determination unit 752, when contact between the robot 10 and the external environment is detected by the external force detection unit 154, (1) A signal input from the robot position calculation unit 151 indicating that the robot 10 is within the set area 90, (2) A signal input from the robot position calculation unit 251 indicating that the robot 10 is within the set area 91, (3) A signal input from the speed calculation unit 351 indicating that the speed of a predetermined movable part of the robot 10 is equal to or greater than a predetermined speed, (4) A signal input from the signal input unit 451 indicating that human contact has been detected by the contact detection sensor 401, (5) A signal input from the signal input unit 551, indicating that the human detection sensor 501 has detected the approach of a person. (6) A signal input from the signal input unit 651, indicating that the hand 30 is closed and gripping the workpiece W, The stop control can be switched based on one of the following:

[0097] If it operates as described in (1) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the first embodiment. If it operates as described in (2) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the second embodiment. If it operates as described in (3) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the third embodiment. If it operates as described in (4) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the fourth embodiment. If it operates as described in (5) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the fifth embodiment. If it operates as described in (6) above, the stop method determination unit 752 performs the stop control switching according to the operation described in the sixth embodiment.

[0098] The stopping method determination unit 752 may be configured to operate in one of the above operations (1) to (6) by the user via a setting screen displayed on the display unit (touch panel, etc.) of the teaching device 40. In this case, the user can select which of the above operations (1) to (6) the robot control device 50G will operate in according to the actual operating environment of the robot system 100G.

[0099] The stop command unit 153 generates a command to stop the robot 10 when the external force detection unit 154 detects contact between the robot 10 and the external environment, according to the control parameters set by the stop method determination unit 752, and sends the command to the robot 10.

[0100] According to the configuration of the robot system 100G described above, the user can configure the robot control device 50G to operate with any of the functions of the robot control devices 50, 50B, 50C, 50D, 50E, and 50F according to the first to sixth embodiments described above.

[0101] Each of the robot control devices according to the above embodiments can be described as "a robot control device for controlling a robot, comprising: an external force detection unit for detecting external forces acting on the robot; and a stop control unit for switching stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, according to a signal indicating the state of the robot or the state of the environment surrounding the robot."

[0102] According to the configurations of each embodiment described above, when contact between the robot and the external environment is detected and the robot is stopped, it becomes possible to achieve more appropriate stop control by dynamically switching the stop control according to the situation.

[0103] Although the present invention has been described above using typical embodiments, those skilled in the art will understand that modifications to the above embodiments and various other modifications, omissions, and additions can be made without departing from the scope of the present invention.

[0104] The signals indicating the state of the robot may include various signals indicating the state of the robot and tools mounted on the robot, in addition to those exemplified in the embodiments described above. Furthermore, the signals indicating the robot's surrounding environment may include various signals indicating the state of the environment surrounding the robot, in addition to those exemplified in the embodiments described above.

[0105] While the robots in each of the embodiments described above are primarily assumed to be collaborative robots, the configurations of each embodiment can also be applied when using ordinary robots other than collaborative robots.

[0106] The functional blocks in the functional block diagrams of the robot control devices shown in each of the embodiments described above may be realized by the robot control device's processor executing various software stored in a memory device, or they may be realized by a hardware-based configuration such as an ASIC (Application Specific Integrated Circuit). [Explanation of Symbols]

[0107] 10 Robots 11 Base 21, 22 Position detection sensors 30 hands 40 Teaching device 50, 50B, 50C, 50D, 50E, 50F, 50G Robot Control Devices 51 processors 52 memory 53 Input / Output Interfaces 54 Operation section 71 Force Sensor 80 tables 81 bogies 90, 91 Setting Area 100, 100B, 100C, 100D, 100E, 100F, 100G Robot System 150 Stop Control Unit 151 Robot position calculation unit 152 Stopping method determining section 153 Stop command section 154 External force detection unit 250 Stop Control Unit 251 Robot position calculation unit 252 Stopping method determination section 350 Stop Control Unit 351 Speed ​​calculation section 352 Stopping method determining section 401 Contact detection sensor 450 Stop Control Unit 451 Signal Input Section 452 Stopping method determination section 501 Human detection sensor 550 Stop Control Unit 551 Signal Input Section 552 Stopping method determining section 650 Stop Control Unit 651 Signal Input Section 652 Stopping method determining section 750 Stop Control Unit 752 Stopping method determination section

Claims

1. A robot control device for controlling a robot, An external force detection unit for detecting external forces acting on the robot, The system includes a stop control unit that switches the stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, in accordance with a signal indicating the state of the surrounding environment of the robot. The stop control unit switches the stop control by changing the type and / or set value of a control parameter, which includes at least one of the following: stop time, acceleration, jerk, motor current, shaft torque, and reversal distance.

2. A robot control device for controlling a robot mounted on a mobile cart, An external force detection unit for detecting external forces acting on the robot, A stop control unit switches the stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, according to a signal indicating the state of the robot or the state of the surrounding environment of the robot. The robot position calculation unit calculates the position of the robot based on the output from a position detection sensor for detecting the position of the trolley, and outputs a second signal indicating whether the calculated position of the robot is within a second set area, as a signal indicating the state of the robot. The stop control unit is a robot control device that switches the stop control according to the second signal.

3. The robot control device according to claim 2, wherein the stop control unit, when an external force exceeding a predetermined value is detected and the robot is stopped, sets the stop time for stopping the robot when the robot's position is within the second setting area to be shorter than the stop time for stopping the robot when the robot's position is outside the second setting area.

4. The robot control device according to claim 2 or 3, wherein the stop control unit, after stopping the robot by the stop control, reverses the robot by a predetermined reversal distance.

5. A robot control device for controlling a robot, An external force detection unit for detecting external forces acting on the robot, A stop control unit switches the stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, according to a signal indicating the state of the robot or the state of the surrounding environment of the robot. The robot comprises a speed calculation unit that calculates the speed of a movable part of the robot based on the output from a sensor provided on the robot, and outputs a third signal indicating whether the calculated speed of the movable part is equal to or greater than a predetermined speed value. The stop control unit switches the stop control according to the third signal. The stop control unit, when stopping the robot, sets the stop time for stopping the robot when the robot's speed is equal to or greater than the predetermined speed value to be longer than the stop time for stopping the robot when the robot's speed is less than the predetermined speed value. The stop control unit switches the stop control by changing the type and / or set value of a control parameter, which includes at least one of the stop time, acceleration, jerk, motor current, shaft torque, and reversal distance. Robot control device.

6. The robot further comprises a signal input unit to which a fourth signal is input from a contact detection sensor consisting of a mechanical switch or touch sensor attached to a specific part of the robot. The robot control device according to claim 1, wherein the stop control unit switches the stop control according to the state of the surrounding environment of the robot, which is indicated as the fourth signal.

7. The robot control device according to claim 6, wherein, when an external force exceeding a predetermined value is detected and the robot is stopped, the stop control unit sets the stop time for stopping the robot when contact to the specific part is detected by the contact detection sensor to be shorter than the stop time for stopping the robot when contact to the specific part is not detected by the contact detection sensor.

8. A robot control device for controlling a robot, An external force detection unit for detecting external forces acting on the robot, A stop control unit switches the stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, according to a signal indicating the state of the robot or the state of the surrounding environment of the robot. The robot comprises a signal input unit that receives a fifth signal from a human detection sensor located in the workspace where the robot is located, The stop control unit switches the stop control according to the fifth signal. The stop control unit switches the stop control by changing the type and / or set value of a control parameter, which includes at least one of the following: stop time, acceleration, jerk, motor current, shaft torque, and reversal distance.

9. The robot control device according to claim 8, wherein the stop control unit, when an external force exceeding a predetermined value is detected and the robot is stopped, sets the stop time for stopping the robot when the human presence sensor detects the approach of a person to the robot to be shorter than the stop time for stopping the robot when the human presence sensor does not detect the approach of a person to the robot.

10. A robot control device for controlling a robot, An external force detection unit for detecting external forces acting on the robot, A stop control unit switches the stop control for stopping the robot when an external force exceeding a predetermined value is detected by the external force detection unit, according to a signal indicating the state of the robot or the state of the surrounding environment of the robot. The robot includes a signal input unit to which a sixth signal indicating the operating state of the hand mounted on the robot is input, The stop control unit is a robot control device that switches the stop control according to the state of the robot indicated as the sixth signal.

11. The robot control device according to claim 10, wherein when an external force exceeding a predetermined value is detected and the robot is stopped, the stop control unit sets the deceleration for stopping the robot when the sixth signal indicates that the hand is closed to a value smaller than the deceleration for stopping the robot when the sixth signal indicates that the hand is open.

12. The robot control device according to any one of claims 2 to 4, 10, or 11, wherein the stop control unit switches the stop control by changing the type and / or set value of a control parameter including at least one of the following: stop time, acceleration, jerk, motor current, axis torque, and reversal distance.

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