control device

Abstract

A control device for controlling a robot, comprising: a force control unit that performs force control based on the detected value of a force detector; and an operation mode changing unit that changes the operation mode of force control based on information relating to the presence or type of mechanism for absorbing external forces applied to the end effector.

Description

Technical Field

[0005]

[0001] This disclosure relates to a control device.

Background Art

[0002] There is known a robot system configured such that an end effector is mounted at the tip of an arm of an articulated robot, and the articulated robot is operated by force control to perform a predetermined task. In this regard, Patent Document 1 describes a robot system that sets a safety mode in a non-detection area of a detector and executes force control in the safety mode. Further, Patent Document 2 describes a hand provided with a floating mechanism that is a mechanism for absorbing an external force load.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the speed of the robot during movement increases, the contact force when the robot contacts an object increases. From the perspective of safety, if the robot is operated at a low speed throughout the working space of the robot, the cycle time of the work becomes long and inefficient. There is a need for a control device that can achieve both safety and efficiency of work by the robot.

Means for Solving the Problems

[0005] One aspect of this disclosure is a control device for controlling a robot, including a force control unit that executes force control based on a detection value of a force detector, and a mechanism for absorbing an external force applied to an end effector <000(0033>The control device is provided with. Another aspect of the present disclosure is a control device for controlling a robot, comprising: a force control unit that performs force control based on the detected value of a force detector; and an operation mode changing unit that, when it obtains information indicating the type of mechanism that absorbs the contact force applied to the end effector, sets the operation mode of the force control to be faster for types of the mechanism that absorb a greater degree of contact force.

[0006] 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]

[0007] [Figure 1] This figure shows the equipment configuration of a robot system according to one embodiment. [Figure 2] This is a functional block diagram of a robot system. [Figure 3] This diagram illustrates a configuration in which an end effector with a floating mechanism is mounted on a robot. [Figure 4] This figure shows an example of the settings screen for a force control approach. [Figure 5] This figure shows an example of an operating program that has a force reference value transfer function. [Figure 6] This figure shows an example of the settings screen for the screw tightening operation icon. [Figure 7] This diagram illustrates the verification of the force reference value transfer function using a measuring instrument. [Figure 8] This is a flowchart illustrating the overall flow of force control operation according to one embodiment. [Modes for carrying out the invention]

[0008] 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.

[0009] Figure 1 shows the equipment configuration of a robot system 100 according to one embodiment. As shown in Figure 1, the robot system 100 comprises a robot 10, a robot control device 20 that controls the robot 10, and a teaching control panel 30 connected to the robot control device 20. A screw tightening machine 60, which serves as an end effector, is attached to the flange 11 of the wrist portion of the robot 10 via a mounting plate 51. A force sensor (force detector) 70 for detecting external forces is attached between the flange 11 of the wrist portion and the mounting plate 51. In this configuration, the robot system 100 can perform various types of force-controlled work by attaching various types of end effectors to the robot 10 according to the work content.

[0010] Figure 1 shows an example configuration in which a screw tightening machine 60 is mounted as an end effector on robot 10. In this configuration, the robot system 100 can perform screw tightening work by force control. In addition to screw tightening machines, end effectors can include various other items depending on the work purpose, such as hands, grinders, and tools.

[0011] Robot 10 is, as an example, a 6-axis vertical articulated robot. However, various types of robots may be used as robot 10, such as horizontal articulated robots, parallel link robots, and dual-arm robots, depending on the task to be performed.

[0012] The robot control device 20 controls the movement of the robot 10 according to an operation program or commands from the teaching control panel 30. The robot control device 20 may have a hardware configuration as a general computer, including a processor 21, memory (ROM, RAM, non-volatile memory, etc.), storage unit 22, operation unit, input / output interface, network interface, etc. (see Figure 2).

[0013] The teaching control panel 30 is used as an operating terminal for teaching the robot 10 and performing various settings. A teaching device consisting of a tablet computer or the like may be used as the teaching control panel 30. The teaching control panel 30 may have a hardware configuration as a general computer, including a processor, memory (ROM, RAM, non-volatile memory, etc.), storage device, operation unit, display unit 31 (see Figure 2), input / output interface, network interface, etc.

[0014] The force sensor 70 is a 6-axis force sensor that detects forces acting in the mutually orthogonal X, Y, and Z axis directions, as well as moments around each axis. In this embodiment, the external force acting on the robot 10 is detected by the force sensor 70, but instead of the force sensor, the external force may be detected by the detected values ​​of torque sensors provided on each axis of the robot.

[0015] End effectors such as screw tightening machines come in two types: those without a floating mechanism and those with a floating mechanism. Figure 1 shows, as an example, a configuration in which an angle-type screw tightening machine 60 without a floating mechanism is mounted on a robot 10. The screw tightening machine 60 illustrated in Figure 1 comprises a main body 61 containing a control unit 161 and a motor 162 (see Figure 2), and a head 62 connected to the tip of the main body 61. The head 62 holds a socket 65 as a tool. A screw 81 is held in the socket 65. The screw tightening machine 60 is connected to a robot control device 20, and, according to commands from the robot control device 20, tightens and fixes the screw 81 into the screw hole of the object. The screw tightening machine 60 is attached to one side of a mounting plate 51, and the other side of the mounting plate 51 is attached to the flange 11 of the robot 10.

[0016] FIG. 3 shows, as an example, a configuration in which a screwing machine 60 having a floating mechanism 66 is mounted on a robot 10. In the example of FIG. 3, two screwing machines 60 having a floating mechanism 66 are attached to the tip of the arm of the robot 10 via a mounting plate 51. The floating mechanism 66 is a mechanism for displacing the tip of the robot (end effector) in one direction when it contacts an object to absorb and relieve the contact force (external force). Examples of the floating mechanism include a mechanism using a spring and a mechanism using an air cylinder. The type of the floating mechanism is represented by, for example, the stroke length L (the maximum displacement amount of the floating mechanism), a coefficient corresponding to the elastic constant, and the like.

[0017] As will be described in detail below, the robot control device 20 according to the present embodiment has a function of changing the operation mode of force control based on information regarding the presence or type of a mechanism for absorbing an external force applied to the end effector. Thereby, the robot control device 20 realizes both the safety and efficiency of the work by the robot.

[0018] FIG. 2 is a functional block diagram of a robot system 100. As shown in FIG. 2, the robot control device 20 includes an operation control unit 121, a force control unit 122, a force data processing unit 123, a setting unit 124, an operation mode change unit 125, a parameter adjustment unit 126, a contact stop control unit 127, and a force reference setting unit 128. These functional blocks may be functional elements realized by a processor 21 of the robot control device 20 executing software. <G

[0019] The robot control device 20 includes a storage unit 22. The storage unit 22 is a storage device composed of, for example, a non-volatile memory or a hard disk device. The storage unit 22 stores various setting information including an operation program for controlling the robot 10, force control parameters, operation parameters, and the like.

[0020] The motion control unit 121 controls the movement of the robot 10 according to the motion program or according to commands from the teaching control panel 30. The robot control device 20 includes a servo control unit (not shown) that performs servo control on the motors 111 of each axis according to the commands for each axis generated by the motion control unit 121.

[0021] The force data processing unit 123 has the function of calculating external forces (force and moment) acting on a predetermined part of the robot 10 (such as the tip of the wrist) based on the detected values ​​of the force sensor 70. The position and orientation of the force sensor 70 can be calculated from the position and orientation of the tip of the wrist of the robot 10 in its coordinate system and the relative position information of the force sensor 70 with respect to the tip of the wrist. Based on the position, orientation, and detected values ​​of the force sensor 70, the force data processing unit 123 can calculate the magnitude of the force and moment, as well as the direction of the force and moment, in an arbitrary coordinate system pre-set for the robot 10.

[0022] The force control unit 122 performs force control based on the force information calculated by the force data processing unit 123 and predetermined force control parameters. The force control unit 122 may also have a function to apply impedance control or the like. The motion control unit 121 works in cooperation with the force control unit 122 to control the operation performed by force control.

[0023] The setting unit 124 provides a function to accept input of various settings for configuring force control operations. The setting unit 124 may also have a function to present a user interface screen for configuring force control operations and accept settings from the user via the user interface screen. Alternatively, the setting unit 124 may have a function to accept input of force control operation setting information from an external device.

[0024] The operation mode change unit 125 provides a function to set or change the force control operation mode (force control parameters) based on information relating to the presence or type of floating mechanism of the end effector mounted on the robot. The operation mode change unit 125 may also have a function to set or change the force control operation mode based on information input by the user. Alternatively, the operation mode change unit 125 may have a function to automatically set or change the force control operation mode based on information relating to the presence or type of floating mechanism of the end effector.

[0025] The parameter adjustment unit 126 provides a function to automatically adjust force control parameters while the robot 10 is performing force-controlled movements. For example, the parameter adjustment unit 126 can search for appropriate force control parameters (pressing force, force control gain, etc.) by repeatedly having the robot 10 perform force-controlled movements (movements involving position and posture correction in screw tightening work, precision fitting work, etc.) while checking the detected values ​​(force and moment) of the force sensor 70 and changing the force control parameters. The function of the parameter adjustment unit 126 is used, for example, to obtain appropriate force control parameters in the preliminary stages before creating or executing a force control application.

[0026] The contact stop control unit 127 detects whether the external force (contact force) calculated from the value detected by the force sensor 70 exceeds the contact determination value (contact termination threshold), and has the function of slowing down or stopping the robot 10 if it is determined that the external force exceeds the contact determination value (contact termination threshold).

[0027] The force reference setting unit 128 provides a function to set the external force obtained based on the detection value of the force sensor 70 before contact with the work object as the reference value for force control. This function of pre-setting a force reference value and applying it as the force reference value in each force control operation will also be called the force reference value transfer function.

[0028] Force control operations include various types of operations, such as screw tightening and grinding, where a target force in the pressing direction is set and force control is executed, as well as operations where target values ​​related to moment and force control gains are included in the operation setting. In this embodiment, as an example, a function is applied to change the operation mode of force control based on information related to the presence or type of floating mechanism of the end effector mounted on the robot, for an operation in which force control is applied to approach a target position such as the work start position on the workpiece (hereinafter also referred to as the force control approach). The force control approach is an operation that improves safety by applying a function by force control when the robot moves and rapidly decelerating or stopping the robot when it comes into contact with the external environment. In this embodiment, by applying a function to change the operation mode of force control based on information related to the presence or type of floating mechanism of the end effector to this force control approach, both safety and efficiency of the operation are achieved.

[0029] Below, three examples of embodiments relating to the modification of the force control operation mode based on information regarding the presence or type of floating mechanism for the end effector, using the setting unit 124 and the operation mode modification unit 125, will be described.

[0030] (First embodiment) Figure 4 shows a setting screen 200 provided by the setting unit 124 regarding the force control approach operation. The setting unit 124 may be configured to cooperate with the teaching control panel 30, display the setting screen 200 on the display unit 31 of the teaching control panel 30, and accept user operations on the setting screen 200 via the operation unit of the teaching control panel 30. Here, an example is shown in which two force control parameters, the forward speed and the contact termination threshold, are used. The forward speed corresponds to the operating speed of the control part of the robot 10. The contact termination threshold corresponds to a determination value for terminating the force control approach by decelerating or stopping the robot when the external force detected by the force sensor exceeds this threshold.

[0031] As shown in Figure 4, the settings screen 200 includes a setting field 211 for setting the operating mode in the force control approach. In the setting field 211, the user selects the normal mode (not using the high-speed mode) if the end effector is of a type that does not have a floating mechanism, and selects the high-speed mode if the end effector has a floating mechanism. The settings screen 200 includes a specification field 212 for specifying the sensor to be used for force control. In the specification field 212, for example, a force sensor 70 can be specified. The settings screen 200 includes a setting field 213 for setting the reference coordinate system when performing force control. External forces are calculated based on the coordinate system set here. In the setting field 213, for example, the tool coordinate system can be set. The settings screen 200 includes a setting field 214 for displaying or setting force control parameters. The setting field 214 includes fields for displaying or setting the travel speed and contact termination value.

[0032] As illustrated in Figure 4, if the user selects the normal mode in the setting field 211 (i.e., "Do not use high-speed mode"), the operation mode change unit 125 may automatically set the forward speed and contact termination threshold to standard values, for example, 200.00 mm / s and 20.000 N. If the user selects the high-speed mode in the setting field 211, the operation mode change unit 125 may automatically set the forward speed to a higher value than that of the normal mode (for example, 400 mm / s). Furthermore, based on the criterion that "when the end effector has a floating mechanism, the contact force acting on the external environment tends to be absorbed and reduced, so the contact termination threshold can be increased," the operation mode change unit 125 may automatically set a larger value as the contact termination threshold in high-speed mode than that of the normal mode. The user can also adjust the forward speed and contact termination threshold by operating the setting field 214.

[0033] As described above, according to the first embodiment, the operating mode (force control parameters) in the force control approach can be adaptively changed based on information set by the user regarding the presence or absence of a floating mechanism for the end effector. This allows the force control parameters to be automatically set to values ​​that take safety into consideration in situations where large contact forces are likely to occur, while the force control parameters can be automatically set to values ​​that prioritize efficiency in situations where contact forces can be reduced. Therefore, it is possible to achieve both safety and efficiency in force control.

[0034] (Second example) The setting screen 200 illustrated in Figure 4 was configured so that the user could specify between normal mode and high-speed mode in the setting field 211. As an embodiment different from this example, the following describes a configuration in which the operation mode change unit 125 automatically sets force control parameters depending on whether or not the end effector has a floating mechanism. The information indicating whether or not the end effector has a floating mechanism is stored as internal robot information in the memory or storage unit 22 of the robot control device 20. Therefore, the operation mode change unit 125 can acquire the information indicating whether or not the end effector has a floating mechanism as internal robot information.

[0035] The operating mode change unit 125 is (1) When the end effector has a floating mechanism, the contact force acting on the external environment is absorbed, so even if the travel speed is increased, it is possible to avoid an increase in the contact force. (2) When the end effector has a floating mechanism, the contact force acting on the external environment tends to be absorbed and reduced, so the contact termination threshold can be raised. Taking this property into consideration, the following rules (r1)-(r2) may be applied to the setting of the progress speed and the contact termination threshold. Rule (r1): The speed of travel when a floating mechanism is present shall be greater than the speed of travel when a floating mechanism is absent. Rule (r2): The contact termination threshold when a floating mechanism is present shall be greater than the contact termination threshold when a floating mechanism is absent.

[0036] Furthermore, the operating mode changing unit 125 is (3) If the end effector does not have a floating mechanism, a larger contact force may be generated if it does not decelerate quickly upon contact. (4) When decelerating at a high speed and with a large deceleration, the robot is prone to vibration; therefore, it is desirable to reduce the acceleration and deceleration when in high-speed mode. Taking this property into consideration, the following rule (r3) may be applied to the setting of acceleration and deceleration. Rule (r3): The acceleration / deceleration when a floating mechanism is present shall be smaller than the acceleration / deceleration when a floating mechanism is absent.

[0037] Table 1 below summarizes the parameter settings based on the above rules (r1) to (r3).

[0038] [Table 1]

[0039] As described above, according to the second embodiment, the operating mode (force control parameters) in the force control approach can be adaptively changed based on information regarding the presence or absence of a floating mechanism for the end effector. This allows the force control parameters to be automatically set to values ​​that prioritize safety in situations where large contact forces are likely to occur, while the force control parameters can be automatically set to values ​​that prioritize efficiency in situations where contact forces can be reduced. Therefore, it is possible to achieve both safety and efficiency in force control.

[0040] (Third embodiment) In the first and second embodiments, the operating mode (force control parameters) in the force control approach was changed depending on whether or not the end effector had a floating mechanism. 3In this embodiment, the operation mode changing unit 125 changes the operation mode of the force control according to the type of floating mechanism attached to the end effector.

[0041] Here, the floating length L and the elastic constant of the floating mechanism are used as the type of floating mechanism. The elastic constant is larger the greater the elasticity (force that restores the strain) and smaller the greater the flexibility. The operating mode changing unit 125 is, (5) The longer the floating length L of the floating mechanism, the more the robot can absorb contact forces even when it comes into contact with the external environment at a high speed. (6) The greater the flexibility of the floating mechanism, the more it can mitigate contact forces even when the robot comes into contact with the external environment at high speeds. Taking this property into consideration, the following rules (r11) and (r12) may be applied to setting the speed of travel. Rule (r11): The longer the floating length, the greater the speed of movement. Rule (r12): The smaller the elastic constant (the greater the flexibility), the greater the propagation speed.

[0042] Furthermore, the operating mode changing unit 125 may apply the following rules (r13) and (r14) to setting the acceleration and deceleration based on the floating length and elastic constant, from the viewpoint of the above properties (4) and (5)-(6). Rule (r13): The longer the floating length, the smaller the acceleration and deceleration. Rule (r14): The smaller the elastic constant (the greater the flexibility), the smaller the acceleration or deceleration.

[0043] Furthermore, the operating mode changing unit 125 is (7) The longer the floating length, the more the contact force at the time of contact can be sufficiently mitigated even when the speed of movement is increased, and thus the contact termination threshold can be raised. (8) The smaller the elastic constant (the greater the flexibility), the more the contact force at contact can be sufficiently mitigated even when the propagation speed is increased, thus raising the contact termination threshold. Considering this property, the following rules (r15) and (r16) may be applied to setting the contact termination threshold based on the type of floating mechanism. Rule (r15): The longer the floating length, the higher the contact termination threshold. Rule (r16): The smaller the elastic constant (the greater the flexibility), the larger the contact termination threshold should be.

[0044] Table 2 below summarizes the setting of force control parameters according to the rules (r11)-(r16) described above.

[0045] [Table 2]

[0046] As described above, according to the third embodiment, the operating mode (force control parameters) in the force control approach can be adaptively changed based on information related to the type of floating mechanism for the end effector. This allows the force control parameters to be automatically set to values ​​that take safety into consideration in situations where large contact forces are likely to occur, while the force control parameters can be automatically set to values ​​that prioritize efficiency in situations where contact forces can be reduced. Therefore, it is possible to achieve both safety and efficiency in force control.

[0047] In the first embodiment described above, a configuration example was explained in which the user can set whether or not to use high-speed mode in the setting field 211. Alternatively, there may be a configuration example in which the setting field 211 of the setting screen 200 has a setting field in which the presence or absence of a floating mechanism and the type of floating mechanism can be set. For example, the setting field 211 may have the following setting items. • A field to specify whether or not a floating mechanism is present. • A field to specify the floating length (for example, specify long or short). • A field to specify the elastic constant (for example, specify large or small). Even in this configuration, the operating mode change unit 125 can automatically set the force control parameters appropriately in the manner described in the second and third embodiments, based on information set by the user regarding the presence or absence of a floating mechanism and the type of floating mechanism.

[0048] Next, the force reference value setting function (force reference value inheritance function) in force control provided by the force reference setting unit 128 will be described. Here, an example configuration in which this function by the force reference setting unit 128 is implemented as a command icon in the operation program will be described. Figure 5 shows the operation program PR1 for performing work using force control. The setting unit 124 may be configured to work in conjunction with the teaching operation panel 30 to display a program creation screen 300 as shown in Figure 5 on the display unit 31, providing a function for the user to create and edit the operation program. The operation program PR1 includes a U-shaped icon 301 that represents the range to which a common force reference value is applied. The common force reference value is applied to icons 302 and 303 that are included in the range enclosed by icon 301. Icon 302 is a command icon for a force control approach. Icon 302 has the function of performing a force control approach according to various parameters set via the setting screen 200 shown in Figure 4, as well as the function of acquiring the external force acting on the robot 10 before the robot 10 comes into contact with the work object, based on the detection value of the force sensor 70. The operating program PR1 further includes an icon 303 for performing screw tightening operations using the screw tightening machine 60.

[0049] Figure 6 illustrates the settings screen 350 for the screw tightening operation icon 303. The settings screen 350 includes a specification field 351 for specifying the sensor to be used in the force control of screw tightening. In the specification field 351, for example, a force sensor 70 is specified. The settings screen 350 includes a settings field 352 for setting the reference coordinate system when performing force control. The external force is calculated based on the coordinate system set here. In the settings field 352, for example, the tool coordinate system can be set. The settings screen 350 includes a settings field 353 for displaying or setting force control parameters. Force control parameters in screw tightening operations include the target force applied to the screw tightening machine 60 (socket 65) in the screw tightening direction, the screw tightening speed, and the screw tightening depth.

[0050] When the operation program PR1 is started, icon 301, the force control approach icon 302, and the screw tightening operation icon 303 are executed in order. In the execution of icon 302, a force control approach is performed in which the robot 10 moves to the target position, and the external force acting on the robot 10 before it contacts the workpiece is measured based on the detection value of the force sensor 70 and set as the force reference value. Next, the screw tightening operation icon 303 is executed to perform a screw tightening operation using force control. Force control in the screw tightening operation is performed so as to press the screw tightening machine 60 (socket) in the screw tightening direction with the target force. The external force at this time is calculated based on the detection value of the force sensor 70 and is a value based on the set force reference value. The force reference value is a value measured based on the detection value of the force sensor 70 before the robot 10 contacts the target workpiece, and is, for example, 0. Therefore, the screw tightening operation by icon 303 is performed with the target set in icon 303. force It will be executed properly according to the rules.

[0051] On the other hand, if the force reference value setting function of the force reference setting unit 128 is not applied, and the force reference value in the force control operation is set when the icon 303 is activated, the measured value of the external force when the robot and the workpiece are in contact and a large external force is acting on the robot will be set as the force control reference for the screw tightening operation. In this case, the screw tightening operation by the icon 303 will be performed with a value greater than the original target force, which is an inappropriate situation.

[0052] In this regard, the force reference value setting function according to this embodiment makes it possible to appropriately perform various force-controlled operations, including screw tightening, polishing, operations using a stamping machine as a tool, and precision fitting, according to the set target force.

[0053] In addition, the above describes an example configuration in which the function of the force reference setting unit 128 (force reference value inheritance function) is realized by an icon 301 configured to allow specifying the scope of application of the instruction. However, the same function as that of the icon 301 can also be realized by an instruction statement in a text-based operation program that is configured to allow specifying the scope of application of the instruction.

[0054] Figure 7 shows the situation in which the force measuring instrument 40 is placed at the workpiece location and the operation program PR1 is executed to verify the force reference value transfer function by the force reference setting unit 128, and the state of the pressing force control during force control execution is monitored. In this case, the rotation of the screw tightening machine 60 is stopped. When measuring force with this measuring instrument 40, the mounting part 40a is placed at the measurement target location and the robot's end effector is in contact with the measurement surface 40b. The measuring instrument 40 is equipped with a display unit 41 that displays the contact force of the measurement result. The display unit 41 displays a graph 400 that shows the change in the contact force measured when the operation program PR1 is executed. Graph 400 shows the change in the measured value of the contact force when the screw tightening icon 303 is executed. The horizontal axis of graph 400 is the time axis, and the vertical axis is the contact force. As shown in region F1 of graph 400 in Figure 7, a large contact force is temporarily generated at the moment the end effector comes into contact with the workpiece (in this case, the measuring instrument 40). However, thereafter, as shown in region F2, the contact force is not affected by the large contact force at the time of contact and remains at a value in line with the target force.

[0055] Figure 8 is a flowchart illustrating the overall flow of the force control operation, from setting the force control operation mode to executing the force control, as described above. The flowchart in Figure 8 is executed primarily under the control of the processor 21.

[0056] First, the user creates a program (step S1). Here, the user adds a command to enable the force reference value inheritance function (icon 301), a force control approach command (icon 302), and a force control work application command (icon 303) to the program. Next, the processor 21 determines whether or not a floating mechanism is attached to the tip of the robot's work tool (step S2). If a floating mechanism is attached to the tip of the work tool (S2: YES), the processor 21 decides to use the high-speed mode of the force control approach (step S3). On the other hand, if a floating mechanism is not attached to the tip of the work tool (S2: NO), the processor 21 decides to use the normal mode of the force control approach (step S4). Then, the processor 21 sets the force control parameters according to the normal mode or high-speed mode, as described above in the first and second embodiments (step S5). Then, the operation from the start of the force control approach to contact with the work object is executed (step S6).

[0057] If the force reference value transfer function is enabled (S7:YES), the processor 21 uses the force obtained based on the detection value of the force sensor 70 when executing the force control approach as the reference value to perform the next force control operation (step S8). On the other hand, if the force reference value transfer function is not enabled, the processor 21 uses the force at the time the robot contacts the work object as the reference value to perform the next force control operation (step S9). Examples of operations where it is appropriate to perform force control based on the force at the time of contact without enabling the force reference value transfer function include operations in which a robot presses a two-stage push button.

[0058] As described above, according to this embodiment, the force control operation mode can be appropriately changed based on information regarding the presence or type of mechanism for absorbing external forces applied to the end effector mounted on the robot. This makes it possible to achieve both safety and efficiency in robotic work.

[0059] In the above-described embodiment, an example was given in which the floating mechanism, which serves as a mechanism for absorbing external forces applied to the end effector, is part of the end effector's configuration. However, the mechanism for absorbing external forces applied to the end effector could also be incorporated, for example, into the wrist flange of a robot.

[0060] The above-described embodiment illustrates an example where the operation performed following the force control approach is a screw tightening operation. Various operations involving force control can be performed following a force control approach, including grinding, precision fitting, tracing, operations using a stamping machine as a tool, and coordinated operation of a robot and a moonlifter.

[0061] In the embodiments described above, it should be understood that not all of the functional blocks in the functional block diagram shown in Figure 2 are essential. Furthermore, the functional arrangement in the functional block diagram shown in Figure 2 is illustrative, and there are various possible variations in the arrangement of functional blocks to realize the functions of the embodiments described above. For example, some of the functional blocks that are located in the robot control device 20 (such as the setting unit 124) may be located in the teaching operation panel 30. The entire function provided by the teaching operation panel 30 and the robot control device 20 may also be defined as the control device.

[0062] In the functional block diagram of Figure 2, each functional block described as a function of the robot control device or teaching control panel may be realized by one or more processors of these devices executing various software stored in a memory device, or in this case, part of the function may be made up of hardware such as discrete circuits (i.e., realization of the functional block by a combination of a processor and discrete circuits), or the functions shown in the functional block diagram may be realized by a hardware-based configuration such as an ASIC (Application Specific Integrated Circuit).

[0063] The computer programs for executing various processes such as force control processing in the above-described embodiments, or the computer programs for executing processes in each part of the processor of the robot control device, may be provided in the form of program products recorded on various computer-readable recording media (for example, semiconductor memories such as ROM, EEPROM, and flash memory, magnetic recording media, or optical recording media such as CD-ROM and DVD-ROM).

[0064] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0065] Further notes regarding the above embodiments and modifications are provided below. (Note 1) A control device (20) for controlling a robot, A force control unit (122) that performs force control based on the detected value of the force sensor, An operating mode changing unit (125) changes the operating mode of the force control based on information relating to the presence or type of mechanism for absorbing external forces applied to the end effector, A control device (20) equipped with the following. (Note 2) The control device (20) described in Appendix 1 changes the operation mode in a force control approach operation in which force control is applied during the process of moving the robot to a target position, based on the information. (Note 3) The control device (20) described in Appendix 1 includes information relating to the type of the mechanism, including the maximum displacement that the mechanism can displace in order to absorb an external force, and one or more coefficients representing the elastic constant. (Note 4) The aforementioned operating mode changing unit (125) is a control device (20) according to any one of the appendices 1 to 3, which changes the force control parameters based on the aforementioned information. (Note 5) The control device (20) described in Appendix 4 includes the force control parameters, the force control progress speed, the contact detection threshold, and the robot's acceleration / deceleration degree of 1 or more. (Note 6) The aforementioned information includes the presence or absence of the aforementioned mechanism, The force control parameters include the force control progression speed, the contact detection threshold, and the robot's acceleration / deceleration speed. The aforementioned operating mode changing unit (125) (Rule 1) The speed of travel when the aforementioned mechanism is present shall be greater than the speed of travel when the aforementioned mechanism is absent. (Rule 2) The contact detection threshold when the mechanism is present shall be greater than the contact detection threshold when the mechanism is absent. (Rule 3) The acceleration / deceleration when the above mechanism is present shall be less than the acceleration / deceleration when the above mechanism is absent. The force control parameters are changed using one or more of the following: The control device (20) described in Appendix 4. (Note 7) The aforementioned information includes, as information relating to the type of mechanism, a coefficient representing the maximum displacement and elastic constant that the mechanism can displace in order to absorb force. The force control parameters include the force control progression speed, the contact detection threshold, and the robot's acceleration / deceleration speed. The aforementioned operating mode changing unit (125) (Rule 1) The greater the maximum displacement, the greater the rate of travel. (Rule 2) The smaller the elastic constant, the greater the velocity of propagation. (Rule 3) The greater the maximum displacement, the smaller the acceleration / deceleration. (Rule 4) The smaller the elastic constant, the smaller the acceleration / deceleration. (Rule 5) The greater the maximum displacement, the higher the contact detection threshold should be. (Rule 6) The smaller the elastic constant, the larger the contact detection threshold. The force control parameters are changed using one or more of the following: The control device (20) described in Appendix 4. (Note 8) The control device (20) according to Appendix 6 or 7, further comprising a contact stop control unit (127) that decelerates or stops the robot when the contact force obtained based on the detected value of the force detector exceeds the contact determination threshold. (Note 9) The robot is the work object and A control device (20) according to any one of the appendices 1 to 8, comprising a force reference setting unit (128) that sets the external force based on the detected value of the force detector before contact as the reference value of the force in the force control. (Note 10) The force reference setting unit (128) is the control device (20) described in Appendix 9, which is configured as an instruction in the operation program. (Note 11) The control device (20) described in Appendix 10 is configured to allow specifying the scope of application of the instruction, and applies the reference value of the force to one or more force control instructions within the scope of application. (Note 12) A control device (20) as described in any one of the appendices 9 to 11, to which the aforementioned force reference value is applied by force control operation, which includes one or more of screw tightening, polishing, stamping machine operation, and precision fitting. (Note 13) A control device (20) according to any one of the appendices 1 to 12, comprising a setting unit (124) for receiving input of information relating to the presence or type of the aforementioned mechanism. (Note 14) The aforementioned operating mode changing unit (125) is a control device (20) according to any one of the appendices 1 to 12, which automatically acquires information relating to the presence or type of the mechanism as internal information of the robot. [Explanation of symbols]

[0066] 10 Robots 11 Flange 20 Robot control devices 30. Instructional control panel 31 Display section 40 Measuring instruments 41 Display section 51 Mounting plate 60 Screw tightening machine 61 Main body 62 Head section 65 sockets 66 Floating Mechanism 70 Force Sensor 111 Motor 121 Operation Control Unit 122 Force Control Unit 123 Force Data Processing Unit 124 Setting section 125 Operation Mode Change Section 126 Parameter adjustment section 127 Contact Stop Control Unit 128 Force standard setting section 161 Control Unit 162 Motor

Claims

1. A control device for controlling a robot, A force control unit that performs force control based on the detected value of a force sensor, When information is obtained indicating whether the end effector has a mechanism for absorbing external forces applied to it, the operation mode change unit sets the operation mode of the force control, which is set when the mechanism is present, to a second operation mode that is faster than the first operation mode of the force control, which is set when the mechanism is not present. A control device equipped with the following features.

2. A control device for controlling a robot, A force control unit that performs force control based on the detected value of a force sensor, When information indicating the type of mechanism that absorbs the contact force applied to the end effector is obtained, the operating mode change unit sets the operating mode of the force control to be faster for types of the mechanism that absorb a greater degree of contact force, A control device equipped with the following features.

3. The control device according to claim 1 or 2, wherein the operation mode changing unit changes the operation mode in a force control approach operation in which force control is applied during the process of moving the robot to a target position, based on the information.

4. The control device according to claim 2, wherein the information indicating the type of the mechanism includes one or more coefficients representing the elastic constant and the maximum displacement that the mechanism can displace in order to absorb the contact force.

5. The control device according to claim 1 or 2, wherein the operating mode changing unit changes the force control parameters based on the information.

6. The control device according to claim 5, wherein the force control parameters include the force control progress speed, a contact detection threshold, and a robot acceleration / deceleration degree of 1 or more.

7. A control device for controlling a robot, A force control unit that performs force control based on the detected value of a force sensor, The system includes an operating mode changing unit that changes the operating mode of the force control based on information relating to the presence or type of mechanism for absorbing external forces applied to the end effector, The operation mode changing unit changes the force control parameters based on the information, The aforementioned information includes the presence or absence of the aforementioned mechanism, The force control parameters include the force control progression speed, the contact detection threshold, and the robot's acceleration / deceleration speed. The aforementioned operating mode changing unit is (Rule 1) The speed of travel when the above mechanism is present shall be greater than the speed of travel when the above mechanism is absent. (Rule 2) The contact detection threshold when the mechanism is present shall be a value greater than the contact detection threshold when the mechanism is absent. (Rule 3) The acceleration / deceleration when the above mechanism is present shall be a smaller value than the acceleration / deceleration when the above mechanism is absent. The force control parameters are changed using one or more of the following: Control device.

8. A control device for controlling a robot, A force control unit that performs force control based on the detected value of a force sensor, The system includes an operating mode changing unit that changes the operating mode of the force control based on information relating to the presence or type of mechanism for absorbing external forces applied to the end effector, The operation mode changing unit changes the force control parameters based on the information, The aforementioned information includes, as information relating to the type of mechanism, a coefficient representing the maximum displacement and elastic constant that the mechanism can displace in order to absorb force. The force control parameters include the force control progression speed, the contact detection threshold, and the robot's acceleration / deceleration speed. The aforementioned operating mode changing unit is (Rule 1) The greater the maximum displacement, the greater the rate of travel. (Rule 2) The smaller the elastic constant, the greater the velocity of propagation. (Rule 3) The greater the maximum displacement, the smaller the acceleration / deceleration. (Rule 4) The smaller the elastic constant, the smaller the acceleration / deceleration. (Rule 5) The greater the maximum displacement, the greater the contact detection threshold. (Rule 6) The smaller the elastic constant, the larger the contact detection threshold should be. The force control parameters are changed using one or more of the following: Control device.

9. The control device according to claim 7, further comprising a contact stop control unit that decelerates or stops the robot when the contact force obtained based on the detection value of the force detector exceeds the contact determination threshold.

10. The control device according to any one of claims 1, 2, 4, 7, 8, or 9, further comprising a force reference setting unit that sets an external force based on the detected value of the force detector before the robot comes into contact with the work object as a reference value for the force in the force control.

11. The control device according to claim 10, wherein the force reference setting unit is configured as an instruction in the operation program.

12. The control device according to claim 11, wherein the command is configured to specify the scope of application of the command, and the reference value of the force is applied to one or more force control commands within the scope of application.

13. The control device according to claim 10, wherein the operation by force control to which the aforementioned reference value of force is applied includes one or more of screw tightening, polishing, work using a stamping machine, and precision fitting.

14. The control device according to claim 1, further comprising a setting unit that receives input of information indicating the presence or absence of the aforementioned mechanism.

15. The control device according to claim 2, further comprising a setting unit that accepts input of information indicating the type of the mechanism.

16. The control device according to claim 1, wherein the operating mode changing unit automatically acquires information indicating the presence or absence of the mechanism as internal information of the robot.

17. The control device according to claim 2, wherein the operating mode changing unit automatically acquires information indicating the type of mechanism as internal information of the robot.

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