Robot control device and robot system

Abstract

A robot control device (3) capable of controlling a robot (2) by guide control in which a posture of the robot (2) is changed in accordance with a magnitude and a direction of a force detected by a force sensor possessed by the robot (2), the robot control device (3) recognizing a first state in which an additional device (30) is attached to a front end of a wrist (4) of the robot (2) and a second state in which the additional device (30) is not attached to the front end of the wrist (4) of the robot (2), and switching a load setting of the robot (2) at the time of executing the guide control between the first state and the second state.

Description

Technical Field

[0001] This invention relates to robot control devices and robot systems. Background Technology

[0002] Previously, technologies were known that allowed inspection devices for weld seams to be detached from tools such as welding torches, thereby expanding the inspection range of the device and eliminating interference with other components (e.g., see Patent Document 1). Additionally, a robot was known that could move via so-called guided control, which involved incorporating sensors to detect forces applied by the operator and changing the robot's position and orientation based on the magnitude and direction of the force detected by the sensors (e.g., see Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-299702

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-34412 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The weld inspection device is installed with a significant protrusion from the robot's wrist or welding torch, so it is only installed during teaching of areas where weld inspection is needed, and removed during teaching of areas where weld inspection is not needed, or before execution begins after teaching. When teaching the robot to move via guided control, the load acting on the robot varies depending on the presence or absence of the inspection device. Therefore, it is desirable to ensure correct robot operation via guided control even if the load acting on the robot changes due to the installation or removal of the device.

[0009] Solution for solving the problem

[0010] A robot control device is provided that can control a robot through guided control, wherein the robot's posture is changed according to the magnitude and direction of the force detected by a force sensor on the robot. The robot control device identifies a first state and a second state, wherein the first state is in which an additional device is installed on the front end of the robot's wrist, and the second state is in which the additional device is not installed on the front end of the robot's wrist. In the first state and the second state, the load setting of the robot is switched when the guided control is executed. Attached Figure Description

[0011] Figure 1This is an overall structural diagram of a robot system according to one embodiment of the present invention.

[0012] Figure 2 It means Figure 1 The main view of the robot system.

[0013] Figure 3 This indicates that it is installed at Figure 1 A partial 3D view of the welding torch, welding torch bracket, handle, and tool bracket at the front end of the robot's wrist in the robotic system.

[0014] Figure 4 It means Figure 1 A block diagram of the robot system. Detailed Implementation

[0015] Hereinafter, a robot control device 3 and a robot system 1 according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] like Figure 1 As shown, the robot system 1 of this embodiment includes: a robot 2, which has a force sensor 10; and a robot control device 3, which controls the robot 2.

[0017] The wrist 4 of robot 2 has a flange 5 at its front end that can rotate around the frontmost rotation axis X, and a tool holder 6 is fixed to the flange 5. In addition, a welding rod holder 7 that supports a long tool such as welding rod 100 is fixed to the tool holder 6. The welding rod holder 7 has two handles 8 and 9 that are held by the operator.

[0018] The welding torque bracket 7 comprises: a bracket body 11, which is fixed to the tool bracket 6; and a fixing block 12, which fixes the welding torque 100 on the bracket body 11 and has handles 8 and 9 fixed thereon.

[0019] The welding torch 100 comprises: a tubular welding torch body 110 that is bent in one direction; a generally cylindrical journal support 120 that is connected to the base end of the welding torch body 110; and a guide tube 130 that is connected to the base end of the journal support 120.

[0020] The guide tube 130, journal support 120, and welding torch body 110 have an inner hole through which the welding wire 140 passes along its length (illustration omitted). The welding torch 100 welds the workpiece by causing the welding wire 140, which has passed through the inner hole, to protrude from the front end of the welding torch body 110 and generate an electric arc between it and the workpiece.

[0021] Because the welding torch 100 has an elongated shape as described above, it cannot penetrate the interior of the wrist 4. Instead, it is supported by the welding torch bracket 7 at an off-center position relative to the rotation axis X of the flange 5. Furthermore, the welding torch body 110 is configured such that it bends from the position fixed to the welding torch bracket 7 along a plane (hereinafter referred to as the tool plane) P containing the rotation axis X of the flange 5, and the welding wire 140 protrudes towards a position intersecting the rotation axis X of the flange 5. The intersection point of the rotation axis X of the flange 5 and the welding wire 140 is generally set as the tool tip point.

[0022] Handles 8 and 9 are a first handle 8 configured along the tool plane P and a second handle 9 configured at a position near the long axis Y of the welding moment 100 and extending in a direction orthogonal to the tool plane P.

[0023] The first handle 8 is a straight rod-shaped component that can be gripped by the operator with their right hand. The first handle 8 is configured to be spaced apart from the welding rod 100 by a gap sufficient to allow the four fingers other than the thumb of the right hand to enter, and is parallel to the major axis Y of the welding rod 100. Thus, the first handle 8 is configured to extend on the tool plane P in the direction along the major axis Y of the welding rod 100.

[0024] A guide switch 13 is provided at the front end of the first handle 8, which can be operated by the thumb of the right hand when holding the first handle 8. The guide switch 13 performs the following functions: the guide control is activated when a pushing force is applied according to the thumb, and the guide control is deactivated when the pushing force is released.

[0025] The second handle 9 is a straight rod-shaped component positioned such that an operator holding the first handle 8 with their right hand can also grip it with their left hand. The fixing block 12 is positioned so that it can be operated by the thumb of the left hand while holding the second handle 9 with the right hand, and it has two push-button switches 14 and 15.

[0026] One push-button switch 14 is a teach button that stores the angles of each axis of robot 2 at the moment of pressing. Another push-button switch 15 is a toggle button that switches the motion mode of robot 2 between orthogonal motion and individual axis motion on each press.

[0027] The tool holder 6 is a rectangular block-shaped component sandwiched between the flange 5 and the welding moment holder 7. The holder body 11 of the welding moment holder 7 is fixed to the front end face of the tool holder 6, which is parallel to the flange 5. Additionally, as... Figure 3 As shown, on three sides of the tool holder 6 parallel to the rotation axis X of the flange 5, there are sensor mounting surfaces (mounting surfaces) 6a for detachably mounting the welding sensor (attachment device) 30. Figure 3 Only one sensor mounting surface 6a is shown in the image.

[0028] The welding sensor 30 can detect the welding line with high precision, for example, by scanning the workpiece with a laser along a direction that intersects with the welding line on the workpiece and detecting the reflected light.

[0029] The sensor mounting surface 6a is provided on three sides of the tool holder 6, such as the left and right sides and the back side when viewed from the welding rod holder 7 side of the tool holder 6.

[0030] The operator can select the sensor mounting surface 6a and install the welding sensor 30 according to the laser scanning direction and the position of the processing line relative to the welding torque 100. The sensor mounting surface 6a is provided with two pin holes 16 and four threaded holes 17. Using bolts and positioning pins, the welding sensor 30 can be installed in a state of high-precision positioning relative to the robot 2.

[0031] Additionally, each sensor mounting surface 6a is equipped with a switch (sensor mounting / removing switch) 18 that is pressed when the welding sensor 30 is mounted. The location of the welding sensor 30 on which sensor mounting surface 6a it is mounted can be detected by the state of the switch 18 located on the sensor mounting surface 6a at the mounting destination.

[0032] exist Figure 1 as well as Figure 2 In the example shown, viewed from the welding moment bracket 7 side, the welding sensor 30 is fixed to the sensor mounting surface 6a on the right side. The welding sensor 30 has a relatively large shape and is configured to extend significantly beyond the sensor mounting surface 6a.

[0033] like Figure 4 As shown, the robot control device 3 includes a storage unit 19 and a control unit 20.

[0034] The control unit 20 includes at least one processor and memory.

[0035] The control unit 20 outputs command signals to control the robot 2 through so-called guided control, in which the posture of the robot 2 is changed according to the magnitude and direction of the force detected by the force sensor 10 of the robot 2.

[0036] like Figure 1 As shown, a welding power source 40 is connected to the robot control device 3, and the welding power source 40 is connected to the welding torch 100 via a guide tube 130. Additionally, a welding sensor connection unit 50 is connected to the robot control device 3, and a sensor control cable 60 connected to the welding sensor 30 is connected to the welding sensor connection unit 50.

[0037] In the second state (where no welding sensor 30 is installed on any of the sensor mounting surfaces 6a, and the welding torque 100 is installed using the welding torque bracket 7), the robot control device 3 stores the load information detected by the force sensor 10 in the storage unit 19. For example, the load information stored is the value detected by the force sensor 10 when the angles of each axis of the robot 2 are configured at the origin position.

[0038] If the angles (axis information) of each axis of robot 2 change, the values ​​detected by force sensor 10 will change. However, control unit 20 can estimate the magnitude and direction of the force detected by force sensor 10 based on the axis information of robot 2 and the load information stored in storage unit 19. Therefore, in the second state where all switches 18 do not detect the installation of welding sensor 30, regardless of the angles of each axis, as long as force sensor 10 detects the estimated value, control unit 20 can process it as a neutral load state (load setting) where no external force is applied.

[0039] In addition, the robot control device 3 stores the quality of the basic information of the welding sensor 30 and the information of the center of gravity position from the sensor mounting surface 6a in the storage unit 19.

[0040] Furthermore, when the switch 18 detects that a welding sensor 30 is installed on any of the sensor mounting surfaces 6a, the control unit 20 changes the neutral load state.

[0041] That is, when the welding sensor 30 is installed (first state), the mass of the welding sensor 30 stored in the storage unit 19 is added to the position where the center of gravity position stored in the storage unit 19 is located away from the detected installation surface 6a of the installed sensor. Therefore, when the first state is detected, the control unit 20 estimates the load information detected by the force sensor 10 based on the mass stored in the storage unit 19, the center of gravity position, and the information of each axis of the robot 2, and sets a new neutral load state.

[0042] Furthermore, when the welding line is detected using the welding sensor 30, the control unit 20 corrects the taught point based on the characteristics of the detected welding line. That is, as the taught point, when the position coordinates of the tip of the welding wire 140 protruding towards the front of the welding moment 100 are set, the coordinates of the taught point are corrected so that it is positioned on the welding line when the taught point deviates from the welding line detected by the welding sensor 30.

[0043] The operation of the robot control device 3 and the robot system 1 configured as described below will be explained.

[0044] When teaching a welding operation using the robot system 1 of this embodiment, the operator first holds the first handle 8 and the second handle 9 of the welding torque bracket 7 in the second state where the welding sensor 30 is not installed on the sensor mounting surface 6a.

[0045] Then, by pressing the guide switch 13 located on the first handle 8, the guide control is activated. Thus, based on the force applied to the first handle 8 and the second handle 9, the robot control device 3 causes the robot 2 to move through the guide control.

[0046] Since the switch 18 located on the sensor mounting surface 6a is in the off state in this second state, the robot control device 3 uses the detection value of the force sensor 10 under neutral load conditions stored in the storage unit 19 as a reference. Furthermore, when the operator applies force to the first handle 8 and the second handle 9, the magnitude and direction of the force detected by the force sensor 10 change, and the robot control device 3 guides the robot 2 to move based on this change.

[0047] With robot 2 configured in the desired posture, the operator can store the angles of each axis of robot 2 at the moment of pressing a button switch 14, which is located near the second handle 9, as a teach button. By repeating this action, the operation program of robot 2 can be taught.

[0048] In the teaching operation in the second state without the welding sensor 30 installed, teaching points such as the start point and relay point of the action program can be taught, even if they are roughly set. In addition, since the relatively large welding sensor 30 is not fixed to the tool holder 6, there is no need to worry about interference between the welding sensor 30 and surrounding parts, and teaching operations can be easily performed even in relatively confined environments.

[0049] Next, when teaching a point requiring precise teaching, such as a welding production line, the operator installs a welding sensor 30 on any sensor mounting surface 6a. If a welding sensor 30 is installed, the switch 18 on the sensor mounting surface 6a where the welding sensor 30 is installed is switched to the ON state. If switch 18 is switched to the ON state, the control unit 20 uses the mass and center of gravity position of the welding sensor 30 stored in the storage unit 19 to change the neutral load state.

[0050] That is, if the welding sensor 30 is installed on the sensor mounting surface 6a, the magnitude and direction of the force detected by the force sensor 10 will change before and after installation. The robot control device 3 can determine that the first state with the welding sensor 30 installed is a neutral load state. Thus, in this first state, when the operator holds the first handle 8 and the second handle 9 and applies force, the robot control device 3 can guide the robot 2 to move to the desired position through guidance control and teach multiple teaching points along the welding work line.

[0051] After teaching multiple teaching points along the welding line, the operator activates the welding sensor 30 and regenerates the taught points along the welding line. This allows the robot 2 to move while the welding sensor 30 scans the laser to detect features of the welding line. If the features of the welding line detected by the welding sensor 30 are input, the control unit 20 corrects the coordinates of each teaching point based on the input features, ensuring that the tool tip of the welding torch 100 is precisely aligned with the welding line.

[0052] After the teaching at the teaching points along the welding work line is completed, the operator removes the welding sensor 30 from the sensor mounting surface 6a and, through guided control, teaches the remaining teaching points while the robot 2 moves. In this case, since the welding sensor 30 is removed from the sensor mounting surface 6a, the switch 18 becomes open and is detected as the second state. Therefore, the control unit 20 returns the neutral load state to the load state stored in the storage unit 19. Thus, the operator can use the force sensor 10 to accurately detect the magnitude and direction of the force applied to the first handle 8 and the second handle 9, and make the robot 2 move in the desired posture.

[0053] Thus, according to the robot control device 3 and robot system 1 of this embodiment, the first state in which the welding sensor 30 is installed on the sensor mounting surface 6a and the second state in which the welding sensor 30 is not installed on the sensor mounting surface 6a are identified, thereby switching the load setting when performing guidance control. As a result, regardless of whether the welding sensor 30, which is relatively heavy and large in shape, is installed, guidance control can be performed accurately, enabling the robot 2 to move in the desired posture.

[0054] In other words, it has the following advantages: Teaching can be performed in the second state, where the welding sensor 30 is removed, even at teaching points where the welding sensor 30 is not required, thus enabling teaching operations without interference from peripheral equipment. Furthermore, even when teaching is performed in the first state with the welding sensor 30 installed, the robot 2 can be accurately guided and controlled regardless of the force exerted by the welding sensor 30 on the force sensor 10. Moreover, it has the following advantages: The characteristics of the welding line can be detected using the welding sensor 30, and teaching points along the welding line can be corrected with high precision.

[0055] Furthermore, in this embodiment, since multiple sensor mounting surfaces 6a are provided on the tool holder 6, the mounting position of the welding sensor 30 can be changed according to the application. It also has the advantage that, regardless of which sensor mounting surface 6a the welding sensor 30 is mounted on, the mounting position of the welding sensor 30 can be detected using the switch 18 provided on each sensor mounting surface 6a, and the neutral load state can be accurately changed.

[0056] In addition, in this embodiment, the installation of the welding sensor 30 onto the sensor mounting surface 6a is detected by using a switch 18 that is physically pressed by the welding sensor 30. However, other types of sensor mounting and dismounting, such as non-contact sensors like Hall elements, can also be used instead.

[0057] Alternatively, instead of the loading / unloading sensor, the first state and the second state can be identified based on the force information detected by the force sensor 10 in the first state and the force information detected by the force sensor 10 in the second state.

[0058] For example, the first and second states can be identified by positioning the robot 2 at the origin in both states and comparing the magnitude and direction of the force detected by the force sensor 10 when no other external force is applied. Alternatively, the installation position of the welding sensor 30 can be detected based on the magnitude and direction of the force detected by the force sensor 10, and the neutral load state can be changed accordingly.

[0059] Furthermore, when installing the welding sensor 30, the signal output from the welding sensor 30 is input to the robot control device 3 by connecting the sensor control cable 60 to the welding sensor 30. Therefore, instead of using the switch 18 (which acts as a loading / unloading sensor) to detect the loading / unloading of the welding sensor 30, the loading / unloading of the welding sensor 30 can be detected by whether the sensor control cable 60 is connected, or whether the output from the welding sensor 30 is input to the robot control device 3. Moreover, when the installation of the welding sensor 30 is detected, the sensor mounting surface 6a on which the welding sensor 30 is installed can be designated based on the force information detected by the force sensor 10.

[0060] Furthermore, while this embodiment exemplifies a robot 2 equipped with an arc welding torque 100, it can also be applied to robots 2 equipped with other tools such as laser welding or sealing equipment. Additionally, as an attachment detachably mounted to the front end of the wrist 4 of the robot 2, a welding sensor 30 for detecting welding lines is exemplified; however, it can also be applied to cases where any other attachment is installed. For example, it could be a sensor for detecting the machining line that forms the path for sealing.

[0061] In addition, to prevent workers from accidentally touching the welding sensor 30, such as Figure 1 as well as Figure 2 As shown by the double-dotted line, a protective component can also be installed to surround the welding sensor 30. For example, a box-shaped metal cover fixed to the tool holder 6 and surrounding the outer peripheral surface of the welding sensor 30 (excluding the laser emission surface) or a protector made of metal tubing can also be used.

[0062] Furthermore, in this embodiment, the example shown is that the sensor mounting surface 6a of the welding sensor 30 is provided at three locations on the tool holder 6, but any number of locations can be provided, more than one. In the case of a single location, it is sufficient to detect whether the welding sensor is being mounted or dismounted. In addition, the form, shape, and configuration of the tool holder 6, welding torque holder 7, handle 8, 9, guide switch 13, push-button switches 14, 15, etc., can be arbitrary.

[0063] Additionally, the example illustrates the case with a first handle 8 and a second handle 9, but there can be only one handle, or none at all. Without a handle, the operator can directly grasp and push / pull the welding torque bracket 7, the tool bracket 6, or the wrist 4 of the robot 2 by hand.

[0064] Explanation of reference numerals in the attached figures:

[0065] 1: Robot System

[0066] 2: Robot

[0067] 3: Robot control device

[0068] 4: Wrist

[0069] 6a: Sensor mounting surface (mounting surface)

[0070] 10: Force sensor

[0071] 18: Switch (for installing / removing sensors)

[0072] 40: Welding sensor (attachment)

Claims

1. A robot control device capable of controlling a robot via guided control, wherein the robot's posture is changed based on the magnitude and direction of a force detected by a force sensor provided with the robot, characterized in that, The robot control device identifies a first state and a second state. The first state is when an additional device is installed at the front end of the robot's wrist, and the second state is when the additional device is not installed at the front end of the robot's wrist. In the first state and the second state, the load setting of the robot is switched when performing guided control.

2. The robot control device according to claim 1, characterized in that, The first state and the second state are identified based on the output of the mounting sensor on the mounting surface of the attachment located at the front of the wrist.

3. The robot control device according to claim 2, characterized in that, The installation position of the additional device in the first state is identified based on the outputs of the loading and unloading sensors respectively disposed on the plurality of mounting surfaces. Based on the installation location, switch the robot's load setting when performing guided control in the first state.

4. The robot control device according to claim 1, characterized in that, The first state and the second state are identified based on the force information detected by the force sensor in the first state and the force information detected by the force sensor in the second state.

5. The robot control device according to claim 4, characterized in that, Based on the force information detected by the force sensor in the first state and the force information detected by the force sensor in the second state, the installation position of the additional device in the first state is identified. Based on the installation location, switch the robot's load setting when performing guided control in the first state.

6. A robot system, characterized in that, have: The robot control device according to any one of claims 1 to 5; and The robot has the force sensor.

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