ROBOT SYSTEM, ROBOT CONTROL DEVICE, CONTROL METHOD AND CONTROL PROGRAM

Abstract

This robotic system comprises a robot, a control device that controls the robot, and a tool attached to the robot that performs a predefined task on a workpiece. Based on an external force acting on the robot, the control device implements force control to move the robot in a direction where the external force is neutralized. The control device varies the degree of force control so that any load acting on the robot is reduced to a state where the tool and workpiece are mutually restrained.

Description

{Technical field}

[0001] The present disclosure relates to robot systems, robot control devices, control methods and control programs. {State of the art}

[0002] A known anchor placement method involves setting an anchor, held by an anchor-setting tool (hereinafter referred to as the "tool") attached to a robot, into a pre-drilled hole provided in a wall (see, for example, patent literature 1). During the insertion of the anchor into the pre-drilled hole, this anchor placement method includes securing the anchor in a held position on the tool and inserting the anchor while controlling the robot to minimize any moment detected by a force sensor attached to the robot. After the anchor has been inserted into the pre-drilled hole, the held position between the anchor and the tool is released, and only an axial impact force is applied to the anchor, thereby suppressing any load acting on the robot's drive shaft. {Reference list}{Patent literature}

[0003] [PTL 1] Japanese unexamined patent application, publication number 2022-72055 {Summary of the invention}{Technical problem}

[0004] However, if the tool is, for example, a screw fastener used to tighten a screw, it is not possible to tighten the screw simply by releasing the screw's clamping force. Therefore, it is desirable to reduce the load acting on each robot shaft during operation while simultaneously maintaining the tool's position against the workpiece. {Solution to the problem}

[0005] One aspect of the present disclosure relates to a robotic system comprising: a robot; a control device that controls the robot; a tool attached to the robot and used to perform a predetermined process on the workpiece; and a sensor that detects an external force acting on the robot. Based on the external force detected by the sensor, the control device implements force control to move the robot in a direction to counteract the external force. Furthermore, the control device changes the degree of force control to reduce a load acting on the robot in a state where the tool and the workpiece are mutually restrained. {Brief description of the drawings} { Fig. 1] Fig. Figure 1 illustrates the overall configuration of a robot system according to an embodiment of the present disclosure. { Fig. 2] Fig. Figure 2 is a partially vertical sectional view of a tool tip and a bolt and illustrates an example of force control by the robot system in Fig. 1. { Fig. 3] Fig. 3 is a flowchart that illustrates a robot control procedure through the robot system in Fig. 1 illustrated. { Fig. 4] Fig. Figure 4 schematically illustrates a model of a robot and a tool in the robot system in Fig. 1. { Fig. 5A} Fig. 5A illustrates a cantilevered beam similar to a case where an enhancement of force control in the model is used. Fig. 4 high. { Fig. 5B} Fig. 5B illustrates a double-supported beam, similar to a case where the reinforcement of the force control in the model is in Fig. 4 is low. { Fig. 6] Fig. Figure 6 is a partially vertical sectional view of the tool tip and bolt and illustrates another example of force control by the robot system in Fig. 1. {Description of the implementation examples}

[0006] A robot system 10, a control device 20 of a robot 1, a control method and a control program according to an embodiment of the present disclosure are described below with reference to the drawings.

[0007] As in Fig. As shown in Figure 1, the robot system 10 according to this embodiment includes the robot 1, the control device 20 for controlling the robot 1, a tool 30 attached to the robot 1 and a sensor 40 for detecting an external force Fs.

[0008] In the Fig. In the example shown, robot 1 is, for instance, a vertical six-axis articulated robot. However, robot 1 is not limited to this and can also have any other configuration.

[0009] The robot 1 comprises a base 2, which is installed on an installation surface B, for example, a floor, and a pivoting body 3, which is held by the base 2 so that it can rotate about a first axis J1, which is vertical. The robot 1 further comprises a first arm 4, which is held by the pivoting body 3 so that it can rotate about a second axis J2, which is horizontal, and a second arm 5, which is held by the first arm 4 so that it can rotate about a third axis J3, which is parallel to the second axis J2. In addition, the robot 1 comprises a three-axis wrist unit 6, which is attached to the distal end of the second arm 5.

[0010] The wrist unit 6 contains a first wrist component 7, which is held by the second arm 5 so that it can rotate about a fourth axis J4, and a second wrist component 8, which is held by the first wrist component 7 so that it can rotate about a fifth axis J5. Furthermore, the wrist unit 6 contains a third wrist component 9, which is held by the second wrist component 8 so that it can rotate about a sixth axis J6. Specifically, the robot 1 contains six rotary joints (hereinafter referred to as "joints") A1 to A6, each of which can rotate about the six axes J1 to J6.

[0011] Each of the joints A1 to A6 contains a motor and a reduction gear, and uses the reduction gear to amplify the torque generated by the motor, thus driving it with high torque. Therefore, as described later, the torques T1 to T6 generated by the joints A1 to A6 correspond to the current values ​​for driving the respective motors.

[0012] The tool 30 is attached to the distal end of the third wrist component 9 and is, for example, a screwdriving tool, such as a nut wrench, equipped with a tool tip 32, such as a socket, designed to engage the head 31a of a bolt 31. The tool 30 rotates the tool tip 32 about a screw axis C1, causing the bolt 31 engaging with the tool tip 32 of the tool 30 to rotate about an axis C2 of the bolt 31, thereby fastening the bolt 31 to a workpiece 33. For example, the tool 30 can switch between low-speed, low-torque rotation and high-speed, high-torque rotation according to a command signal transmitted by the control device 20.

[0013] The workpiece 33 is a device, a machine, or a component with at least one threaded bore 33a for attaching the bolt 31 to it. The workpiece 33 is fixed directly or indirectly to the installation surface B, such as a floor surface.

[0014] The sensor 40 for detecting the external force Fs contains, for example, torque sensors 40a to 40f, each located in the joints A1 to A6 of the robot 1, which detect the torques T1 to T6 acting on the joints A1 to A6 about the axes J1 to J6. Specifically, the sensor 40 detects the external force Fs acting on the robot 1 as the torques T1 to T6 acting on the joints A1 to A6 about the axes J1 to J6.

[0015] The control device 20 according to this embodiment includes at least one processor and at least one memory, such as a ROM and a RAM. The processor executes an operating program stored in the memory to operate the robot 1 and also implements force control for the robot 1 according to a control program stored in the memory.

[0016] The force control includes causing the robot 1 to work in a direction to counteract the external force Fs when the external force Fs is calculated on the basis of the torques T1 to T6 detected by the sensor 40.

[0017] A robot control method according to this embodiment is described below using an example in which the screw 31, which is loosely attached to the threaded bore 33a in the workpiece 33, is tightened again, as is the case, for example, in Fig. 2 is shown.

[0018] As in Fig. As shown in Figure 3, at the beginning of the operating program, the processor sets the force control amplification to a high level (step S1). The processor then determines whether a screwing operation based on the operating program has been completed (step S2). If the screwing operation has not been completed, the processor calculates the external force Fs acting on the distal end of the third wrist component 9 based on the torques T1 to T6 detected by sensor 40 (step S3).

[0019] Specifically, the processor calculates the Jacobi matrix based on the orientation information of the robot 1 and calculates the external force Fs acting on the distal end of the robot 1 based on the torques T1 to T6 detected by the sensor 40 and the Jacobi matrix.

[0020] The Jacobian matrix is ​​calculated using formula 1. J=[s1⋯s6s1×r1⋯s6×r6]

[0021] In this case, s1 to s6 denote direction vectors along the axes J1 to J6 of joints A1 to A6. Furthermore, r1 to r6 denote position vectors from joints A1 to A6 to the point of application of the external force Fs acting on the distal end of the third wrist component 9.

[0022] A vector V obtained by combining an angular velocity ω and a translational velocity v at the distal end of the third wrist component 9 of the robot 1 can be expressed by expression 2. V=Jθ'

[0023] In this case, θ' denotes a collection vector of the angular velocities of all joints A1 to A6.

[0024] Using the relationship given in expression 2, the external force Fs acting on the third wrist component 9 of the robot 1 is calculated as a combination of force and moment on the basis of expression 3. Fs=−[OIIO]J−Tτ=−[OIIO][s1⋯s6s1×r1⋯s6×r6]−Tτ

[0025] In this case, τ denotes a collective vector of the torques T1 to T6 acting on all joints A1 to A6.

[0026] By executing the operating program, the tool 30 is actuated, causing the tool tip 32 to rotate around the screw axis C1 at low speed and low torque, while the tool tip 32 is moved closer to the bolt head 31a in accordance with the movement of the robot 1. When the tool tip 32 comes into contact with the bolt head 31a, an external force is generated that causes the bolt head 31a to push back against the tool tip 32.

[0027] The processor determines whether any of the components of the calculated external force Fs exceeds a predetermined threshold (step S4). The predetermined threshold is stored in memory for each component.

[0028] If none of the components of the external force Fs exceeds the threshold, the processor instructs robot 1 to work in the direction of canceling the external force Fs based on the calculated external force Fs (compliance control: step S5). For example, as in Fig. Figure 2 shows that an external force Fz is generated along the screw axis C1, and that external forces Fx and Fy are generated orthogonally to it. In this case, the tool 30 is moved in the same direction (i.e., in the direction indicated by arrow D) as the external forces Fx and Fy generated perpendicular to the screw axis C1. The external force Fz is not subject to force control.

[0029] Accordingly, the screw axis C1 of the tool tip 32 can be aligned with the axis C2 of the bolt 31, and the tool tip 32 can be engaged with the bolt head 31a.

[0030] When the tool tip 32 engages with the bolt head 31a, the processor issues a command signal to make the tool 30 operate at high speed and high torque in the operating program.

[0031] As the tool tip 32 continues to rotate in accordance with the actuation of the tool 30, the bolt 31 is fastened to the threaded bore 33a, and the bolt head 31a abuts the workpiece 33. At this point, the tool 30 and the workpiece 33 are held against each other around the screw axis C1, and the torque acting around the screw axis C1 increases rapidly.

[0032] If the processor detects in step S4 that one of the components of the external force Fs has exceeded the predetermined threshold, the processor reduces the force control gain (step S6). Specifically, the processor performs the force control and switches the degree of force control in a decreasing direction in the state where the tool 30 and the workpiece 33 are mutually held.

[0033] The processor then repeats the steps from step S2. When the processor determines in step S2 that the screwing operation is complete, it terminates the operation. The determination of the end of the screwing operation can be based, for example, on the duration of the screwing operation by the high-speed, high-torque screwdriving tool.

[0034] The following describes the operation of the robot system 10 according to this embodiment with the configuration described above.

[0035] In the robot system 10 according to this embodiment, the control device 20 performs force control on the robot 1 with relatively high amplification until the tool tip 32 engages with the bolt head 31a.

[0036] Specifically, the control device 20 causes the robot 1 to operate in the direction of canceling the external force Fs, according to a highly reactive force control, until the tool tip 32 engages with the bolt head 31a. Accordingly, the robot 1 can be operated in such a way that the screw axis C1 is quickly aligned with the axis C2 of the bolt 31.

[0037] When the screw axis C1 is aligned with the axis C2 of the bolt 31, the low-speed rotating tool tip 32 engages the bolt head 31a in each phase around the screw axis C1. The engagement of the tool tip 32 in the bolt head 31a can be detected using a coordinate value of each of the joints A1 to A6 of the robot 1.

[0038] On the other hand, after detecting an increase in the tightening torque by the tool tip 32, the control device 20 reduces the force control amplification in order to decrease the responsiveness of the force control. Accordingly, the robot 1 does not actively work towards reducing the torque even if the torque about the screw axis C1 increases rapidly.

[0039] Consequently, during the process of tightening the screw 31 using the tool 30, the robot 1 is prevented from working in the direction of counteracting the torque acting about the screw axis C1, thus increasing the force acting on the tool 30 in the direction orthogonal to the screw axis C1. However, the present inventors have found that the torques acting about the axes J1 to J6 of the robot 1 decrease significantly by changing the reinforcements compared to not changing them.

[0040] Fig. Figure 4 schematically illustrates a model of the screwing process by the tool 30, which is attached to the distal end of the third wrist component 9 of the robot 1. The robot 1 is held at the mounting surface B on the base 2 at its lower end. In a state where the tool tip 32 engages with the bolt head 31a, the tool tip 32 is also held against the mounting surface B at its distal end due to the engagement between the tool tip 32 and the bolt head 31a.

[0041] It is conceivable that the degree of constraint between the tool tip 32 and the installation surface B is low when the force control amplification is high, and conversely, that the degree of constraint between the tool tip 32 and the installation surface B is high when the force control amplification is low. This is similar to the relationship between a cantilevered beam and a double-supported beam, as in the Fig. 5A and Fig. 5B is shown.

[0042] Specifically, in the case of the Fig. Figure 5A shows a cantilevered beam with one end 50a fixed, while the other end 50b is not fixed. Therefore, if a moment M acts on beam 50, the other end 50b experiences a large displacement, causing the beam 50 to deform considerably. Consequently, a large stress acts on one end 50a of beam 50.

[0043] On the other hand, in the Fig. In Figure 5B, the doubly supported beam fixes the opposite ends 50a and 50b of beam 50. Therefore, when the moment M acts on beam 50, a force F acts on the opposite ends 50a and 50b of beam 50, thus reducing the deformation of beam 50. Consequently, the stress acting on one end 50a of beam 50 is reduced compared to the case of a cantilevered beam. In other words, the force F acting on the opposite ends 50a and 50b of beam 50 supports beam 50 and thereby reduces the stress acting on beam 50.

[0044] In the state where the tool tip 32 and the bolt head 31a are engaged, the base 2 and the tool tip 32, which serve as opposite ends of the robot 1, can be held against the mounting surface B by reducing the force control gain. Accordingly, the force acting on the opposite ends of the robot 1, similar to the doubly supported beam, supports the robot 1, thus suppressing deformations occurring at the joints A1 to A6 of the robot 1. This reduces the load acting on each of the joints A1 to A6 compared to the case where the force control gain is high.

[0045] By changing the degree of force control, this embodiment thus enables both rapid engagement of the tool tip 32 in the bolt head 31a and reduced stress on each of the joints A1 to A6 during the screwing process. In this embodiment, the moments acting about the fifth axis J5 and the sixth axis J6 tend to increase due to a rapid rise in torque about the screw axis C1 caused by tightening the bolt 31. By reducing the moments acting about the fifth axis J5 and the sixth axis J6, it is possible to prevent the moments acting about axes J1 to J6 from exceeding a permissible torque, thus ensuring that the robot 1 remains in perfect working order.

[0046] In this embodiment, the external force Fs acting on the distal end of the robot 1 is estimated based on the torques T1 to T6 acting on joints A1 to A6, which are detected by the sensor 40, comprising the torque sensors 40a to 40f contained in the respective joints A1 to A6. Alternatively, a six-axis force sensor can be arranged at any position on the robot 1, and the external force Fs can be estimated based on the six-axis forces and moments detected by the force sensor. The six-axis force sensor is capable of detecting six force components, including forces acting along three mutually orthogonal axes and moments acting about the three axes, and can only be arranged between the third wrist component 9 and the tool 30.

[0047] Alternatively, each of the joints A1 to A6 can be equipped with a secondary encoder. The external force Fs can be estimated based on deviations between the positions of joints A1 to A6 output by the secondary encoder and the positions of joints A1 to A6 calculated based on the encoders provided in the motors. The secondary encoder is separate from the encoders provided in the motors and is a detector that directly measures the displacement of each of the joints A1 to A6.

[0048] Sensor 40 for detecting the external force Fs is not strictly necessary. The external force Fs can be estimated, for example, based on the current values ​​of the motors driving joints A1 to A6.

[0049] The estimation of the external force Fs based on the six-axis forces and moments, the positional deviations of the joints A1 to A6 or the current values ​​of the motors can be carried out using the Jacobi matrix, similar to the case where the estimation is carried out based on the torques T1 to T6.

[0050] In this embodiment, all components of the external force Fs are monitored, and the force control gain is changed if any component exceeds the predetermined threshold. Alternatively, monitoring can be focused only on a specific component of the external force that increases particularly due to a screwing operation. An example of an external force component that increases particularly due to a screwing operation is one acting orthogonally to the screw axis C1. Furthermore, the force control gain can be changed based on the torque acting about the screw axis C1, which is detected by sensor 40.

[0051] Instead of changing the force control gain, the force control can be switched between an activated and a deactivated mode. Switching the force control to the deactivated mode is equivalent to changing the degree of force control. Furthermore, instead of changing the force control gain, the condition for force control can be changed. Examples of this include switching between contact force control and non-contact force control, as well as changing pressure forces.

[0052] As an alternative to changing the force control level by monitoring the external force Fs, the force control level can be changed by monitoring the engagement between the tool tip 32 and the bolt head 31a. The engagement or disengagement can be detected by monitoring the aforementioned coordinate value of robot 1 or the amount of movement (path of movement) of robot 1. If the time required from the start to the end of the engagement according to the force control can be estimated to a certain extent, the operating time can be monitored.

[0053] As an alternative to this embodiment, in which the tool tip 32 formed from a bushing engages with the bolt head 31a of, for example, a hexagonal bolt, a hexagonal wrench can engage with the bolt head of a bolt with a hexagonal hole. This embodiment is not limited to the case in which the bolt 31 is fastened and can be applied to a case in which, for example, a nut is fastened to a press-fit bolt.

[0054] Furthermore, the above example refers to a case in which the bolt 31, which is loosely attached to the threaded bore 33a of the workpiece 33, is tightened after engagement with a socket. Alternatively, as in Fig.As shown in Figure 6, the screw tool supports the bolt 31 with an outer engagement surface 31b, and the bolt 31 can be fastened to the threaded bore 33a with an inner engagement surface 33b provided in the workpiece 33. In this case, the engagement of the outer engagement surface 31b with the inner engagement surface 33b occurs under force control, and after engagement, the screwing operation can be carried out by reducing the force control amplification.

[0055] Although this embodiment relates to the robot system 10, which performs the screwing operation using the screw tool, the embodiment is not limited to this. The robot system 10, the control device 20, and the control method according to this embodiment can be applied to any other process in which the orientation of the tool 30 is first set according to the force control and then the degree of force control is changed.

[0056] Examples of other processes include drilling holes, tapping threads with a tapping tool, grinding with a grinding machine, punching with a punching machine, and a process using a tracer arm, lifting clamp, or the like.

[0057] In this embodiment, the force control gain is reduced when an external force component acting orthogonally to the screw axis C1 exceeds the threshold value. In this case, a stiffness matrix can be obtained according to the orientation of the robot 1, and the optimal gain can be found by estimating the load reduction per unit of gain change based on the stiffness matrix.

[0058] Although the force control amplification is reduced after the tool tip 32 engages the screw head 31a and not before engagement, the direction of change for the force control amplification can be changed according to the orientation of the robot 1 during the screwing process. Depending on the external force, the load acting on each of the joints A1 to A6 changes according to the orientation of the robot 1.

[0059] For example, if the orientation of robot 1 is such that the external force has a significant influence on the moments acting about axes J5 and J6, the force control gain can be reduced to decrease the loads acting on joints A5 and A6, as mentioned above. Conversely, if the orientation of robot 1 is such that the external force has a greater influence on the moments acting about axes J1 to J4 than on the moments acting about axes J5 and J6, the force control gain can be increased. The load factors of all joints A1 to A6 can be controlled to 100% or less by reducing the moments acting about axes J1 to J4, rather than increasing the moments acting about axes J5 and J6.

[0060] If the force control is to be switched to deactivated mode after the tool tip 32 has engaged with the bolt head 31a according to the force control of robot 1, robot 1 can operate in such a way that the force acting about the screw axis C1 is further increased. In this case, robot 1 can, for example, operate based on positive feedback, positive displacement, or the like. Alternatively, a component other than the force acting about the screw axis C1 can be increased.

[0061] Since the optimal force control amplification varies depending on the mounting orientation of the tool 30 attached to the distal end of the third wrist component 9 and the orientation of the robot 1, the amplification can be learned multiple times to minimize the load.

[0062] Furthermore, an input unit can be provided that allows a user to select whether or not to change the level of force control. The input unit used can be any input device, such as a button displayed on a monitor, for example, on control unit 20 or a training device, a keyboard, or a mouse.

[0063] To verify the effect caused by changing the degree of force control, a load factor (%) can be displayed or saved as the ratio of each of the moments acting about the axes J1 to J6 of joints A1 to A6 to the permissible moment. The load factor can be displayed or saved for each joint, or it can be displayed or saved only for one or more specific joints A1 to A6. The sum of the load factors of all joints A1 to A6, their average, or an evaluation value calculated based on any other function can be displayed or saved.

[0064] Instead of the moments of joints A1 to A6, a load factor of any other component can be displayed or stored. It is preferable that the name of the operating program and the line number of an operating program, along with the maximum load factor or similar information, are displayed or stored together.

[0065] In this embodiment, the control device 20, which controls the robot 1, calculates the external force Fs based on the torques T1 to T6 detected by the torque sensors 40a to 40f. Alternatively, the calculation of the external force Fs based on the torques T1 to T6 can be performed by a processor other than the control device 20.

[0066] In addition to the robot system 10, the control device 20 of the robot 1 and the control method described above according to this embodiment, a control program can be configured that causes a computer to execute the control method described above.

[0067] With regard to the embodiment and modifications described above, the following additional features are further disclosed. [Feature 1]

[0068] A robot system comprising: a robot; a control device that controls the robot; and a tool attached to the robot and used to perform a predetermined process on a workpiece, wherein the control device implements force control based on an external force acting on the robot to operate the robot in a direction to counteract the external force, and the control device changes a degree of force control to reduce a load acting on the robot in a state in which the tool and the workpiece are mutually restrained. [Feature 2]

[0069] The robot system according to feature 1 further comprises a sensor that detects the external force acting on the robot. [Feature 3]

[0070] The robot system according to feature 1, wherein the control device calculates the external force acting on the robot. [Feature 4]

[0071] The robot system according to one of features 1 to 3, wherein the load acting on the robot is at least one of the loads acting on the joints of the robot and is calculated on the basis of the external force and an orientation of the robot when the external force is detected. [Feature 5]

[0072] The robot system according to feature 4, wherein the loads acting on the joints are forces or moments in multiple directions. [Feature 6]

[0073] The robot system according to one of features 1 to 5, wherein the control device changes the degree of force control based on at least one component of the external force. [Feature 7]

[0074] The robot system according to one of features 1 to 5, wherein the control device changes the degree of force control based on an operating time or a movement distance of the robot. [Feature 8]

[0075] The robot system according to one of features 1 to 7, wherein the degree of force control changes by changing a force control amplification. [Feature 9]

[0076] The robot system according to one of features 1 to 7, wherein the degree of force control changes by changing a setpoint of the force control. [Feature 10]

[0077] The robot system according to one of features 1 to 7, wherein the degree of force control changes by switching the force control to an activated mode or a deactivated mode. [Feature 11]

[0078] The robot system according to one of features 1 to 10, wherein the control device determines a direction of change for force control based on an orientation of the robot. [Feature 12]

[0079] The robot system according to one of features 1 to 11, wherein the tool comprises a screw tool and wherein the control device changes the degree of force control on the basis of at least one moment acting about a screw axis. [Feature 13]

[0080] The robot system according to one of features 1 to 11, wherein the tool comprises a screw tool and wherein the control device changes the degree of force control on the basis of at least one force acting in a direction orthogonal to a screw axis. [Feature 14]

[0081] Control device of a robot to which a tool is attached, wherein the tool is used to perform a predetermined process on a workpiece, the control device comprising: at least one processor, wherein the processor implements force control based on an external force acting on the robot to move the robot in a direction to counteract the external force, and wherein the processor changes a degree of force control to reduce a load acting on the robot in a state in which the tool and the workpiece are mutually restrained. [Feature 15]

[0082] Control method for a robot to which a tool is attached, wherein the tool is used to perform a predetermined process on a workpiece, the control method comprising: implementing force control based on an external force acting on the robot, wherein the force control moves the robot in a direction to counteract the external force, and changing a degree of force control to reduce a load acting on the robot to a state in which the tool and the workpiece are mutually restrained. [Feature 16]

[0083] A control program for a robot to which a tool is attached, wherein the tool is used to perform a predetermined process on a workpiece, wherein the control program causes a computer to execute a process comprising: implementing force control based on an external force acting on the robot, wherein the force control moves the robot in a direction to counteract the external force, and changing a degree of force control to reduce a load acting on the robot to a state in which the tool and the workpiece are mutually restrained. {Reference symbol list} 1 robot 10 robot systems 20 Control device 30 tools 33 workpiece 40 Sensor 40a, 40b, 40c, 40d, 40e, 40f Torque sensor A1, A2, A3, A4, A5, A6 swivel joint (joint) C1 screw axle Fs external force QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-72055

[0003]

Claims

[1] Robot system comprising: a robot; a control device that controls the robot; and a tool that is attached to the robot and used to perform a predetermined process on a workpiece, wherein the control device implements force control based on an external force acting on the robot to move the robot in a direction to counteract the external force, and wherein the control device changes the degree of force control to reduce the load acting on the robot in a state in which the tool and the workpiece are mutually restrained. [2] Robot system according to claim 1, further comprising a sensor that detects the external force acting on the robot. [3] Robot system according to claim 1, wherein the control device calculates the external force acting on the robot. [4] Robot system according to one of claims 1 to 3, wherein the load acting on the robot is at least one of the loads acting on the joints of the robot and is calculated on the basis of the external force and an orientation of the robot when the external force is detected. [5] Robot system according to claim 4, wherein the loads acting on the joints are forces or moments in multiple directions. [6] Robot system according to any one of claims 1 to 5, wherein the control device changes the degree of force control based on at least one component of the external force. [7] Robot system according to any one of claims 1 to 5, wherein the control device changes the degree of force control based on an operating time or a movement distance of the robot. [8] Robot system according to any one of claims 1 to 7, wherein the degree of force control changes by changing an amplification of the force control. [9] Robot system according to any one of claims 1 to 7, wherein the degree of force control changes by changing a setpoint of the force control. [10] Robot system according to any one of claims 1 to 7, wherein the degree of force control changes by switching the force control to an activated mode or a deactivated mode. [11] Robot system according to any one of claims 1 to 10, wherein the control device determines a change direction for force control based on an orientation of the robot. [12] Robot system according to any one of claims 1 to 11, wherein: the tool includes a screwdriver and The control device changes the degree of force control based on at least one moment acting about a screw axis. [13] Robot system according to any one of claims 1 to 11, wherein: the tool includes a screwdriver and The control device changes the degree of force control based on at least one force acting in a direction orthogonal to a screw axis. [14] Control device of a robot to which a tool is attached, wherein the tool is used to carry out a predetermined process on a workpiece, the control device comprising: at least one processor, wherein the processor implements force control based on an external force acting on the robot to move the robot in a direction to counteract the external force, and wherein the processor changes a degree of force control to reduce a load acting on the robot in a state in which the tool and the workpiece are mutually restrained. [15] Control method for a robot to which a tool is attached, wherein the tool is used to carry out a predetermined process on a workpiece, the control method comprising: Implementing force control based on an external force acting on the robot, wherein the force control moves the robot in a direction to counteract the external force, and changing a degree of force control to reduce a load acting on the robot to a state in which the tool and the workpiece are mutually restrained. [16] Control program for a robot to which a tool is attached, wherein the tool is used to carry out a predetermined process on a workpiece, wherein the control program causes a computer to execute a process comprising: Implementing force control based on an external force acting on the robot, wherein the force control moves the robot in a direction to counteract the external force, and changing a degree of force control to reduce a load acting on the robot to a state in which the tool and the workpiece are mutually restrained.

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