Robot control method and fitting jig

Abstract

To provide a robot control method and a fitting jig that can accurately determine the fitting state of each fitting portion.SOLUTION: A robot comprises: a robot arm in which multiple arms are rotatably connected via joints; a pressing member provided at a tip of the robot arm and pressing the first member and the second member; and multiple sensors provided on the pressing member at positions corresponding respectively to the multiple first fitting portions and detecting reaction force generated by fitting operation. The robot control method comprises: a pressing step in which the robot arm is driven so that the multiple first fitting portions and the multiple second fitting portions fit together, causing the pressing member to press the first members and the second members, and the reaction force is detected by each sensor; and a determination step in which fitting states of the first members and the second members are determined on the basis of detection values of the respective sensors.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a robot control method and a fitting jig. [Background technology]

[0002] In recent years, in order to improve the efficiency and uniformity of work, manufacturing, processing, assembly, and other operations have been performed using robots with robot arms, as shown in Patent Document 1, for example. A known assembly operation is a fitting operation in which components having fitting portions are pressed together with the tip of a robot arm to fit them together. During this fitting operation, it is necessary to determine whether the fitting has been completed or whether the fitting was successful.

[0003] Whether or not the mating operation is complete is determined using a force detection unit that has a built-in force sensor etc. provided on the robot arm. Specifically, the force detection unit detects the three-dimensional components of the reaction force that occurs when mating is performed, and whether or not the mating operation is complete can be determined based on the detected values. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-194521 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the robot described in Patent Document 1, when the parts to be fitted have multiple fitting portions, it is not possible to easily and accurately determine which fitting portions are fitted properly and which fitting portions are not fitted properly, or whether the fitting portions are fitted properly when the area of ​​the fitting portions is large. [Means for solving the problem]

[0006] A method for controlling a robot of the present invention is a method for controlling a robot that performs a fitting operation of fitting a first member having a plurality of first fitting portions with a second member having a plurality of second fitting portions that respectively fit with the plurality of first fitting portions, The robot a robot arm in which a plurality of arms are rotatably connected via joints; a pressing member provided at a tip end of the robot arm and configured to press the first member and the second member; a plurality of sensors provided on the pressing member at positions corresponding to the plurality of first fitting portions, the sensors detecting a reaction force generated by the fitting operation; a pressing step in which the robot arm is driven to press the first member and the second member with the pressing member so that the plurality of first fitting portions and the plurality of second fitting portions are fitted together, and the reaction force is detected by each of the sensors; and a determining step of determining a fitted state of the first member and the second member based on the detection values ​​of the sensors.

[0007] A method for controlling a robot of the present invention is a method for controlling a robot that performs a fitting operation of fitting a first member having an annular first fitting portion with a second member having an annular second fitting portion that fits with the first fitting portion, The robot a robot arm in which a plurality of arms are rotatably connected via joints; a pressing member provided at a tip end of the robot arm and configured to press the first member and the second member; a plurality of sensors provided on the pressing member at positions corresponding to the first fitting portion, the sensors detecting a reaction force generated by the fitting operation; a pressing step of pressing the first member and the second member with the pressing member by driving the robot arm so that the first fitting portion and the second fitting portion fit together, and detecting the reaction force with each of the sensors; and a determining step of determining a fitted state of the first member and the second member based on the detection values ​​of the sensors.

[0008] The fitting jig of the present invention includes a pressing member attached to a tip end of a robot arm of a robot that performs fitting work of fitting a first member having a plurality of first fitting portions and a second member having a plurality of second fitting portions that respectively fit with the plurality of first fitting portions by driving the robot arm, and that presses the first member and the second member; The pressing member includes a plurality of sensors provided at positions corresponding to the plurality of first fitting portions, the sensors detecting reaction forces generated by the fitting operation. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a robot system that executes a robot control method of the present invention. [Figure 2] FIG. 2 is a block diagram of the robot system shown in FIG. [Figure 3] FIG. 3 is a perspective view of a first member and a second member that are targets for fitting by the robot shown in FIG. [Figure 4] FIG. 4 is a side view showing the tip of the robot arm shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. [Figure 6] FIG. 6 is a graph showing the change over time in the detected value of the sensor shown in FIG. [Figure 7] FIG. 7 is a flowchart illustrating an example of a method for controlling a robot according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A robot control method and a fitting jig according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0011] <Embodiment> FIG. 1 is a diagram showing the overall configuration of a robot system that executes a robot control method of the present invention. FIG. 2 is a block diagram of the robot system shown in FIG. 1. FIG. 3 is a perspective view of work objects, i.e., a first member and a second member, on which the robot shown in FIG. 1 performs a fitting operation. FIG. 4 is a side view showing the tip of the robot arm shown in FIG. 1. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. FIG. 6 is a graph showing changes over time in the detection value of the sensor shown in FIG. 4. FIG. 7 is a flowchart for explaining an example of a robot control method of the present invention.

[0012] In the following description, for the sake of convenience, the side of the robot arm 10 facing the base 11 in FIG. 1 will be referred to as the "base end" and the opposite side as the "tip."

[0013] As shown in FIG. 1, the robot system 100 includes a robot 1, a fitting jig 4, and a control device 3 that controls the robot 1.

[0014] First, the robot 1 will be described. In this embodiment, the robot 1 shown in FIG. 1 is a single-arm, six-axis vertical articulated robot, and includes a base 11 and a robot arm 10. An end effector can be attached to the tip of the robot arm 10. The end effector may be a component of the robot 1, or may be a separate member from the robot 1, i.e., it does not have to be a component of the robot 1.

[0015] The robot 1 is not limited to the configuration shown in the figure, and may be, for example, a double-arm articulated robot or a horizontal articulated robot.

[0016] The robot 1 can perform various tasks such as transporting the work object 9, assembling, disassembling, painting, and polishing, but below we will explain the case where it performs assembly work between the first member 91 and the second member 92, particularly fitting work.

[0017] The base 11 is a support that drivably supports the robot arm 10 at its base end, and is fixed to, for example, the floor of a factory. The base 11 of the robot 1 is electrically connected to the control device 3 via a relay cable. Note that the connection between the robot 1 and the control device 3 is not limited to a wired connection as shown in FIG. 1, and may be, for example, a wireless connection. Furthermore, the connection may also be via a network such as the Internet.

[0018] In this embodiment, the robot arm 10 has a first arm 12, a second arm 13, a third arm 14, a fourth arm 15, a fifth arm 16, and a sixth arm 17, which are connected in this order from the base 11 side toward the tip side. The number of arms that the robot arm 10 has is not limited to six, and may be, for example, one, two, three, four, five, or seven or more. The size of each arm, such as its overall length, is not particularly limited and can be set as appropriate.

[0019] The base 11 and the first arm 12 are connected via a first joint 171. The first arm 12 is rotatable around a first rotation axis extending in the vertical direction relative to the base 11. In this way, the first rotation axis coincides with the normal to the floor surface to which the base 11 is fixed, and the entire robot arm 10 can rotate in either the forward or reverse direction around the first rotation axis.

[0020] The first arm 12 and the second arm 13 are connected via a second joint 172. The second arm 13 is rotatable relative to the first arm 12 about a second rotation axis that extends horizontally.

[0021] The second arm 13 and the third arm 14 are connected via a third joint 173. The third arm 14 is rotatable about a third rotation axis that extends horizontally relative to the second arm 13. The third rotation axis is parallel to the second rotation axis.

[0022] The third arm 14 and the fourth arm 15 are connected via a fourth joint 174. The fourth arm 15 is rotatable relative to the third arm 14 about a fourth rotation axis that is parallel to the central axis of the third arm 14. The fourth rotation axis is perpendicular to the third rotation axis.

[0023] The fourth arm 15 and the fifth arm 16 are connected via a fifth joint 175. The fifth arm 16 is rotatable relative to the fourth arm 15 around a fifth rotation axis. The fifth rotation axis is perpendicular to the fourth rotation axis.

[0024] The fifth arm 16 and the sixth arm 17 are connected via a sixth joint 176. The sixth arm 17 is rotatable around a sixth rotation axis relative to the fifth arm 16. The sixth rotation axis is perpendicular to the fifth rotation axis.

[0025] The sixth arm 17 is the robot tip located at the most distal end of the robot arm 10. The sixth arm 17 can be displaced by being driven by the robot arm 10.

[0026] In the following description, the first arm 12, the second arm 13, the third arm 14, the fourth arm 15, the fifth arm 16, and the sixth arm 17 will be collectively referred to as "arms," ​​and the first joint 171, the second joint 172, the third joint 173, the fourth joint 174, the fifth joint 175, and the sixth joint 176 will be collectively referred to as "joints."

[0027] The robot 1 includes motors M1, M2, M3, M4, M5, and M6 as drive units, and encoders E1, E2, E3, E4, E5, and E6. The motor M1 is built into the first joint 171 and rotates the first arm 12 relative to the base 11 around the first rotation axis. The motor M2 is built into the second joint 172 and rotates the first arm 12 and the second arm 13 relatively around the second rotation axis. The motor M3 is built into the third joint 173 and rotates the second arm 13 and the third arm 14 relatively around the third rotation axis. The motor M4 is built into the fourth joint 174 and rotates the third arm 14 and the fourth arm 15 relatively around the fourth rotation axis. The motor M5 is built into the fifth joint 175 and rotates the fourth arm 15 and the fifth arm 16 relatively around the fifth rotation axis. The motor M6 is built into the sixth joint 176 and rotates the fifth arm 16 and the sixth arm 17 relatively around the sixth rotation axis.

[0028] Furthermore, encoder E1 is built into the first joint 171 and detects the position of motor M1. Encoder E2 is built into the second joint 172 and detects the position of motor M2. Encoder E3 is built into the third joint 173 and detects the position of motor M3. Encoder E4 is built into the fourth joint 174 and detects the position of motor M4. Encoder E5 is built into the fifth joint 175 and detects the position of motor M5. Encoder E6 is built into the sixth joint 176 and detects the position of motor M6. Note that "detecting position" here refers to detecting the rotation angle of the motor, i.e., the amount of rotation including forward and reverse, and the angular velocity, and the detected information is referred to as "position information."

[0029] 2, motor drivers D1 to D6 are connected to corresponding motors M1 to M6, respectively, and control the driving of these motors. Motor drivers D1 to D6 are built into a first joint 171, a second joint 172, a third joint 173, a fourth joint 174, a fifth joint 175, and a sixth joint 176, respectively.

[0030] Encoders E1 to E6, motors M1 to M6, and motor drivers D1 to D6 are each electrically connected to the control device 3. Position information of motors M1 to M6 detected by encoders E1 to E6, i.e., the amount of rotation, is transmitted to the control device 3 as an electrical signal. Then, based on this position information, the control device 3 outputs control signals to motor drivers D1 to D6 shown in FIG. 2 to drive motors M1 to M6. In other words, controlling the robot arm 10 means controlling the operation of first arm 12 to sixth arm 17 belonging to the robot arm 10 by controlling the driving of motors M1 to M6.

[0031] As shown in Fig. 1, a fitting jig 4 is provided at the tip of the robot arm 10, i.e., the tip of the sixth arm 17. The fitting jig 4 is a jig for fitting together a first member 91 and a second member 92, which are work objects 9 of the fitting operation. First, the first member 91 and the second member 92 will be described.

[0032] 3 and 4, the first member 91 and the second member 92 are each rectangular in plan view, and are assembled to form the work object 9, which is a box. That is, the first member 91 and the second member 92 are each composed of half of a box.

[0033] Specific examples of the work object 9 made of the box body include disposable lunch boxes made of paper, resin, etc., food cases for takeout or storage, and other food cases, in which the second member 92 is the box body and the first member 91 is the lid. However, the types, uses, etc. of the first member 91 and the second member 92 are not limited to these.

[0034] The first member 91 has a first fitting portion 911A, a first fitting portion 911B, a first fitting portion 911C, a first fitting portion 911D, a first fitting portion 911E, a first fitting portion 911F, a first fitting portion 911G, and a first fitting portion 911H.

[0035] The second member 92 has a second fitting portion 921A, a second fitting portion 921B, a second fitting portion 921C, a second fitting portion 921D, a second fitting portion 921E, a second fitting portion 921F, a second fitting portion 921G, and a second fitting portion 921H.

[0036] When the first member 91 and the second member 92 are stacked and pressed in a direction that brings them closer together, the first fitting portion 911A and the second fitting portion 921A fit together, the first fitting portion 911B and the second fitting portion 921B fit together, the first fitting portion 911C and the second fitting portion 921C fit together, the first fitting portion 911D and the second fitting portion 921D fit together, the first fitting portion 911E and the second fitting portion 921E fit together, the first fitting portion 911F and the second fitting portion 921F fit together, the first fitting portion 911G and the second fitting portion 921G fit together, and the first fitting portion 911H and the second fitting portion 921H fit together.

[0037] The set of first fitting portion 911A and second fitting portion 921A is called fitting portion 9A, the set of first fitting portion 911B and second fitting portion 921B is called fitting portion 9B, the set of first fitting portion 911C and second fitting portion 921C is called fitting portion 9C, the set of first fitting portion 911D and second fitting portion 921D is called fitting portion 9D, the set of first fitting portion 911E and second fitting portion 921E is called fitting portion 9E, the set of first fitting portion 911F and second fitting portion 921F is called fitting portion 9F, the set of first fitting portion 911G and second fitting portion 921G is called fitting portion 9G, and the set of first fitting portion 911H and second fitting portion 921H is called fitting portion 9H. In the following description, each of fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G and 9H will be referred to as a "fitting portion", and fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G and 9H will also be collectively referred to simply as a "fitting portion".

[0038] In this embodiment, there are a plurality of fitting portions, i.e., eight fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, but the number of fitting portions is not limited to this and may be a minimum of 1. In this case, for example, a fitting portion may be configured with a first annular fitting portion formed on the first member 91 and a second annular fitting portion formed on the second member 92 and having a shape corresponding to the first fitting portion.

[0039] When the first member 91 and the second member 92 are stacked, the fitting operation is completed by properly fitting the fitting portions 9A to 9H together. In this embodiment, each of the fitting portions 9A to 9H has a recess and a protrusion, and is configured as a concave-convex fitting portion in which the protrusion is inserted or fitted into the recess, and is particularly called a snap fit. Fitting portions such as these, which are represented by snap fits, generate a certain amount of impact force (hereinafter referred to as a "reaction force") when fitting together.

[0040] The fitting jig 4 has a pressing member 40 and a plurality of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H. The fitting jig 4 may be detachably or fixedly installed at the tip of the sixth arm 17, but in this embodiment, a case where it is detachably installed will be described.

[0041] The pressing member 40 has a first pressure plate 40A and a second pressure plate 40B. The first pressure plate 40A and the second pressure plate 40B are attached to the tip of the robot arm 10 with the sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H held therebetween in a predetermined arrangement as shown in FIG.

[0042] The first pressure plate 40A is fixed to the tip of the sixth arm 17 of the robot arm 10. The second pressure plate 40B is located on the opposite side of the first pressure plate 40A (lower side in FIG. 4) with sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H in between, and presses the first member 91 and the second member 92 in the direction indicated by arrow F in FIG. 4. Arrow F in FIG. 4 points in the direction from the first pressure plate 40A to the second pressure plate 40B. In other words, it points in the direction from the pressing member 40 toward the installation surface on which the work object 9 is placed. Although not shown, the first pressure plate 40A and the second pressure plate 40B are fixed in place with bolts at multiple locations.

[0043] Such first pressure plate 40A and second pressure plate 40B can apply pressure to sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H, thereby improving the detection accuracy of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H.

[0044] Sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H detect the reaction force generated by the mating operation. Sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H are configured to detect loads and are composed of, for example, load cells. As shown in FIG. 2, sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H are each electrically connected to control device 3, and the values ​​detected by sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H are transmitted to control device 3 as electrical signals.

[0045] 5, sensors 4A, 4B, 4C, 4D, 4E, 4F, and 4G are disposed at positions corresponding to the above-mentioned fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, respectively. That is, when fitting jig 4 presses overlapping first member 91 and second member 92 in the direction indicated by arrow F in FIG. 4, sensor 4A is positioned directly above first fitting portion 911A and second fitting portion 921A, sensor 4B is positioned directly above first fitting portion 911B and second fitting portion 921B, sensor 4C is positioned directly above first fitting portion 911C and second fitting portion 921C, and sensor 4D is positioned directly above first fitting portion 911A and second fitting portion 921A. Sensor 4A is positioned directly above first fitting portion 911A to 911H and second fitting portion 921A to 921H, sensor 4B is positioned directly above first fitting portion 911D and second fitting portion 921D, sensor 4E is positioned directly above first fitting portion 911E and second fitting portion 921E, sensor 4F is positioned directly above first fitting portion 911F and second fitting portion 921F, sensor 4G is positioned directly above first fitting portion 911G and second fitting portion 921G, and sensor 4H is positioned directly above first fitting portion 911H and second fitting portion 921H. Note that sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H do not have to be positioned directly above first fitting portions 911A to 911H and second fitting portions 921A to 921H, and may be positioned in any location where they can detect the reaction force, i.e., where there is a large change in the reaction force.

[0046] Sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H can each detect the reaction force received from the work object 9 at any time when the fitting jig 4 presses the work object 9, i.e., the stacked first member 91 and second member 92, in the direction indicated by arrow F in Figure 4.

[0047] Using this fitting jig 4, a fitting operation is performed as described below, and the control device 3 determines the fit state of the first member 91 and the second member 92. Here, determining the fit state of the first member 91 and the second member 92 means determining whether the fit of the fitting portions is successful or unsuccessful. More specifically, if all of the fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H are successful, the first member 91 and the second member 92 are determined to be "successful fit," and if there is a fit failure of even one of the fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, the first member 91 and the second member 92 are determined to be "unsuccessful fit."

[0048] Next, the control device 3 will be described. As shown in Fig. 1, in this embodiment, the control device 3 is installed at a position separate from the robot 1. However, this configuration is not limiting, and the control device 3 may be built into the base 11. The control device 3 has a function of controlling the driving of the robot 1, and is electrically connected to each of the above-mentioned parts of the robot 1. As shown in Fig. 2, the control device 3 has a control unit 31, a storage unit 32, and a communication unit 33. These units are connected to each other so that they can communicate with each other, for example, via a bus.

[0049] The control unit 31 is configured by, for example, a CPU (Central Processing Unit), and reads and executes various programs such as operation programs stored in the storage unit 32. Signals generated by the control unit 31 are transmitted to each part of the robot 1 via the communication unit 33, and signals from each part of the robot 1 are received by the control unit 31 via the communication unit 33. This allows the robot arm 10 to perform a predetermined task under predetermined conditions.

[0050] In addition, the control unit 31 drives the robot arm 10 to perform a pressing step (step S101 in FIG. 7) in which the pressing member 40 presses the first member 91 and the second member 92 in the direction indicated by the arrow F in FIG. 4 so as to fit the first member 91 and the second member 92 together, and performs a determination step (step S102 in FIG. 7) to determine the fit state of the first member 91 and the second member 92.

[0051] The storage unit 32 stores various programs and the like to be executed by the control unit 31. Specifically, the storage unit 32 stores programs and the like for executing a pressing step (step S101 in FIG. 7) and a determining step (step S102 in FIG. 7). Examples of the storage unit 32 include a configuration including a volatile memory such as a RAM (Random Access Memory), a non-volatile memory such as a ROM (Read Only Memory), and a removable external storage device.

[0052] The communication unit 33 transmits and receives signals to and from the control device 3 using an external interface such as a wired LAN (Local Area Network) or a wireless LAN. In this case, communication may be performed via a server (not shown), or via a network such as the Internet.

[0053] When performing the fitting operation, first, as a pre-process, first member 91 and second member 92 shown in Fig. 3 are arranged one on top of the other. In this state, first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G, and 911H and corresponding second fitting portions 921A, 921B, 921C, 921D, 921E, 921F, 921G, and 921H are not yet fitted together.

[0054] This pre-process placement work may be performed manually by a worker, by driving the robot arm 10, or by another robot having a robot arm equipped with an end effector such as a hand at the tip.

[0055] Even when the fitting jig 4 is not yet attached to the tip of the robot arm 10 of the robot 1, the attachment work is included in the preceding process.

[0056] (Pressing step: S101 in Figure 7) Next, with the fitting jig 4 attached to the tip of the sixth arm 17 of the robot arm 10 as shown in Fig. 4, the robot arm 10 is driven and moved so that the pressing member 40 presses the first member 91 and the second member 92 in the direction indicated by the arrow F in Fig. 4. This pressing causes the first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G, and 911H of the first member 91 and the second member 92 to fit into the corresponding second fitting portions 921A, 921B, 921C, 921D, 921E, 921F, 921G, and 921H, respectively.

[0057] During this pressing, sensor 4A is located directly above first fitting portion 911A and second fitting portion 921A, sensor 4B is located directly above first fitting portion 911B and second fitting portion 921B, sensor 4C is located directly above first fitting portion 911C and second fitting portion 921C, sensor 4D is located directly above first fitting portion 911D and second fitting portion 921D, and sensor 4E is located directly above first fitting portion 911E. The robot arm 10 is driven in an orientation such that sensor 4E is positioned directly above first fitting portion 911E and second fitting portion 921E, sensor 4F is positioned directly above first fitting portion 911F and second fitting portion 921F, sensor 4G is positioned directly above first fitting portion 911G and second fitting portion 921G, and sensor 4H is positioned directly above first fitting portion 911H and second fitting portion 921H. When the first and second fitting portions are annular, 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H are arranged in an annular shape directly above the first and second fitting portions.

[0058] Sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H detect the reaction force of each fitting portion at any time from the start to the end of pressing by pressing member 40. That is, sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H detect the reaction force of each fitting portion over time (continuously) from the start to the end of pressing by pressing member 40.

[0059] When the fitting portions are fitted together, sensor 4A detects a reaction force due to the fitting of first fitting portion 911A and second fitting portion 921A, sensor 4B detects a reaction force due to the fitting of first fitting portion 911B and second fitting portion 921B, sensor 4C detects a reaction force due to the fitting of first fitting portion 911C and second fitting portion 921C, and sensor 4D detects a reaction force due to the fitting of first fitting portion 911D and second fitting portion 921D. Sensor 4E detects the reaction force due to the mating of the first mating portion 911E and the second mating portion 921E, sensor 4F detects the reaction force due to the mating of the first mating portion 911F and the second mating portion 921F, sensor 4G detects the reaction force due to the mating of the first mating portion 911G and the second mating portion 921G, and sensor 4H detects the reaction force due to the mating of the first mating portion 911H and the second mating portion 921H.

[0060] (Determination step: S102 in Figure 7) Sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H detect the reaction force of each mating portion over time when mating occurs, and transmit the detected values ​​to control device 3. Below, a representative description will be given of the determination of whether the mating of first mating portion 911A and second mating portion 921A is appropriate or inappropriate, i.e., whether the mating is successful or unsuccessful, based on the detected value of sensor 4A.

[0061] Fig. 6 is a graph showing the change over time in the detection value of sensor 4A, with the vertical axis representing reaction force F and the horizontal axis representing time T. In Fig. 6, the solid line indicates a case where first fitting portion 911A and second fitting portion 921A are successfully fitted together, and the dashed line indicates a typical example (representative example) where fitting between first fitting portion 911A and second fitting portion 921A is unsuccessful.

[0062] When the pressing member 40 starts pressing the first fitting portion 911A and the second fitting portion 921A from time t1, the reaction force gradually increases, and when the first fitting portion 911A and the second fitting portion 921A are mated, a peak PA is formed. The maximum value of the reaction force at peak PA is defined as reaction force FA1. After the time when reaction force FA1 is reached, the value of the reaction force gradually decreases and converges at reaction force FA2. When the first fitting portion 911A and the second fitting portion 921A are successfully mated, the reaction force follows this pattern of change over time.

[0063] On the other hand, if the mating between the first mating portion 911A and the second mating portion 921A fails, a curve similar to that described above will be formed, but a peak PB will be formed that is lower in value than peak PA. Note that a mating failure between the first mating portion 911A and the second mating portion 921A may occur, for example, when a foreign object is inserted between the first mating portion 911A and the second mating portion 921A (between the first member 91 and the second member 92).

[0064] The maximum value of the reaction force at peak PB is reaction force FB1. Reaction force FB1 is smaller than the reaction force FA1 at the time of success. After the time when reaction force FB1 is reached, the value of the reaction force gradually decreases and converges at reaction force FB2. Reaction force FB2 is larger than reaction force FA2. The most common cause of reaction force FB1 < reaction force FA1 and reaction force FB2 > reaction force FA2 is the insertion of a foreign object as mentioned above.

[0065] In this way, the change in reaction force over time and the pattern of the reaction force curve differ depending on whether the first fitting portion 911A and the second fitting portion 921A are properly fitted together, that is, whether the fitting is successful or not (whether the fitting is proper or not). In addition to the reaction forces FA1 and FB1 and the reaction forces FA2 and FB2 as described above, there are also differences in the following points.

[0066] The sharpness of the peak including peak PA is greater than the sharpness of the curve before and after peak PB, i.e., the half-width of the peak including peak PA is greater than the half-width of the peak including peak PB.

[0067] The rate of change in the reaction force up to the reaction force FA1 of the peak PA, ie, the rate of increase (slope), is greater than the rate of change in the reaction force up to the reaction force FB1 of the peak PB, ie, the rate of increase (slope).

[0068] The rate of change in the reaction force after the reaction force FA1 at the peak PA, ie, the rate of decrease, is greater than the rate of change in the reaction force after the reaction force FB1 at the peak PB, ie, the rate of decrease.

[0069] In addition to a state in which a foreign object is inserted between the first member 91 and the second member 92, the following can also cause the first and second mating portions 911A and 921A to fail to engage. For example, the positions of the first and second mating portions 911A and 921A do not match, preventing mating and causing the first or second member to be pressed and deformed. In this case, the reaction force does not converge like the reaction force FB2 in FIG. 6, but continues to decrease.

[0070] The above-mentioned various points in the change in reaction force over time differ depending on whether the first fitting portion 911A and the second fitting portion 921A are properly fitted together. Based on the differences in the above various points, the control unit 31 determines whether the fitting is proper, i.e., whether the fitting is successful or unsuccessful. Specifically, it determines whether the following criteria (1), (2), (3), (4), and (5) are met.

[0071] Judgment criteria (1) A first threshold value FS1 is set in advance, and it is determined whether the reaction force (reaction force FA1 or FB1) at the peak of the reaction force change over time is equal to or greater than the first threshold value FS1. The first threshold value FS1 is a value between the reaction force FA1 and the reaction force FB1, and is stored in the storage unit 32.

[0072] The peak value of the detected reaction force is compared with a first threshold value FS1, and if the peak value is equal to or greater than the first threshold value FS1, such as peak PA, a relatively high impact force is generated at the moment of mating, and it is determined that the mating is successful. Conversely, if the peak value is less than the first threshold value FS1, such as peak PB, it is determined that the mating is unsuccessful.

[0073] Judgment criteria (2) A second threshold value FS2 is set in advance, and it is determined whether the magnitude of the reaction force is equal to or less than the second threshold value FS2 after the decrease from the peak of the reaction force has converged, for example, 0.3 seconds to 5 seconds after the peak.

[0074] The second threshold value FS2 is a value between the reaction force FA2 and the reaction force FB2, and is stored in the storage unit 32.

[0075] The reaction force after the decrease from the peak has converged is compared with the second threshold value FS2. If the reaction force is equal to or less than the second threshold value FS2, such as reaction force FA2, the reaction force received from the mating portion is reduced due to proper mating, and the mating is determined to be successful. Conversely, if the reaction force exceeds the second threshold value FS2, such as reaction force FB2, the mating is determined to be unsuccessful.

[0076] Judgment criteria (3) A third threshold is set in advance, and it is determined whether the half-value width of the mountain including the peak of the reaction force is equal to or less than the third threshold.

[0077] The third threshold value is a value between the half width of peak PA and the half width of peak PB, and is stored in the storage unit 32.

[0078] The half-width of the mountain including the peak of the reaction force is compared with a third threshold value. If the half-width is equal to or less than the third threshold value, the increase and decrease in the reaction force before and after the peak is steep, and the mating is determined to be successful. Conversely, if the half-width exceeds the third threshold value, the mating is determined to be unsuccessful.

[0079] Judgment criteria (4) A fourth threshold value is set in advance, and it is determined whether the rate of increase in the reaction force up to the peak of the reaction force is equal to or greater than the fourth threshold value.

[0080] The fourth threshold value is a value between the rate of increase in the reaction force up to the reaction force FA1 of the peak PA and the rate of increase in the reaction force up to the reaction force FB1 of the peak PB, and is stored in the storage unit 32.

[0081] The rate of increase of the reaction force up to the peak of the reaction force is compared with a fourth threshold value. If the rate of increase is equal to or greater than the fourth threshold value, the increase in the reaction force is steep and the mating is determined to be successful. Conversely, if the rate of increase is less than the fourth threshold value, the mating is determined to be unsuccessful.

[0082] Judgment criteria (5) A fifth threshold is set in advance, and it is determined whether the rate of decrease in the reaction force after the peak of the reaction force is equal to or greater than the fifth threshold.

[0083] The fifth threshold value is a value between the rate of decrease in the reaction force after the reaction force FA1 of the peak PA and the rate of decrease in the reaction force after the reaction force FB1 of the peak PB, and is stored in the storage unit 32.

[0084] The rate of decrease in the reaction force after its peak is compared with a fifth threshold value. If the absolute value of the rate of decrease is equal to or greater than the fifth threshold value, the decrease in the reaction force is steep and the mating is determined to be successful. If the rate of decrease is less than the fifth threshold value, the mating is determined to be unsuccessful.

[0085] The values ​​of the first threshold value FS1, the second threshold value FS2, the third threshold value, the fourth threshold value and the fifth threshold value can be prepared in advance based on the results of, for example, performing similar fitting operations using the same robot 1 and fitting jig 4 on a plurality of samples of work objects 9 that should be successfully fitted and a plurality of samples of work objects 9 that should be unsuccessfully fitted, obtaining and compiling data on the change over time in the reaction force from sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H for each sample, and performing calculations as necessary.

[0086] In this embodiment, the criteria (1), (2), (3), (4), and (5) are applied to the fitting portion 9A, and when all of these criteria are satisfied, the fitting between the first fitting portion 911A and the second fitting portion 921A is determined to be successful. This makes it possible to easily and accurately determine whether the fitting between the first fitting portion 911A and the second fitting portion 921A is successful or unsuccessful.

[0087] In the present invention, the criteria are not limited to any of the above criteria (1), (2), (3), (4) and (5).

[0088] In addition, in the present invention, when at least one of the criteria (1), (2), (3), (4), and (5) is satisfied, it may be determined that the first fitting portion 911A and the second fitting portion 921A are successfully fitted together. Hereinafter, some specific examples will be described.

[0089] (Example 1) If the judgment criterion (1) is satisfied and at least one of the judgment criteria (2), (3), (4), and (5) is satisfied, it is judged as a successful fit; otherwise, it is judged as a failed fit.

[0090] (Example 2) If the judgment criterion (2) is satisfied and at least one of the judgment criteria (1), (3), (4), and (5) is satisfied, it is judged as a successful fit; otherwise, it is judged as a failed fit.

[0091] (Example 3) When both criteria (1) and (2) are met, it is determined that the mating is successful; otherwise, it is determined that the mating is unsuccessful.

[0092] (Example 4) When at least one of the criteria (1) and (2) is satisfied, it is determined that the mating is successful, and otherwise it is determined that the mating is unsuccessful.

[0093] (Example 5) If both criteria (1) and (2) are satisfied and at least one of criteria (3), (4), and (5) is satisfied, the mating is determined to be successful; otherwise, the mating is determined to be unsuccessful.

[0094] (Example 6) If either or both of criteria (1) and (2) are satisfied, and at least one of criteria (3), (4), and (5) is satisfied, the mating is determined to be successful; otherwise, the mating is determined to be unsuccessful.

[0095] (Example 7) When either or both of the criteria (3) and (4) are satisfied, it is determined that the mating is successful; otherwise, it is determined that the mating is unsuccessful.

[0096] (Example 8) When either or both of the criteria (3) and (5) are satisfied, it is determined that the mating is successful; otherwise, it is determined that the mating is unsuccessful.

[0097] (Example 9) When either or both of the criteria (3) and (4) are satisfied and the criteria (5) is also satisfied, it is determined that the mating is successful; otherwise it is determined that the mating is unsuccessful.

[0098] (Example 10) If either or both of criteria (3) and (4) are satisfied, and also criteria (5) is satisfied, and either or both of criteria (1) and (2) are satisfied, it is determined that the mating is successful; otherwise it is determined that the mating is unsuccessful.

[0099] (Example 11) If all of the criteria (3), (4), and (5) are satisfied, and only one of the criteria (1) and (2) is satisfied, it is determined that the mating is successful; otherwise, it is determined that the mating is unsuccessful. (Example 12) Any combination of two or more of the above (Example 1) to (Example 11).

[0100] The above-exemplified criteria (1), (2), (3), (4) and (5) or combinations thereof (such as Examples 1 to 12) can be appropriately selected depending on various conditions, such as the number, shape, structure, arrangement, size, etc. of the fitting portions of the work object 9, the type, function, performance, number of sensors 4A to 4H, arrangement, etc., the desired detection accuracy, the desired judgment accuracy, etc.

[0101] For the mating of parts other than mating part 9A formed by first mating part 911A and second mating part 921A, i.e., first mating part 911B and second mating part 921B, first mating part 911C and second mating part 921C, first mating part 911D and second mating part 921D, first mating part 911E and second mating part 921E, first mating part 911F and second mating part 921F, first mating part 911G and second mating part 921G, and first mating part 911H and second mating part 921H, the success or failure of the mating (whether or not the mating is proper) is determined in the same manner as above, based on the detection values ​​of sensors 4B, 4C, 4D, 4E, 4F, 4G and 4H.

[0102] If it is determined that the fitting is successful at all of the fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, it is determined that the fitting is successful for the first member 91 and the second member 92. On the other hand, if it is determined that the fitting is unsuccessful at any one of the fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, it is determined that the fitting is unsuccessful for the first member 91 and the second member 92.

[0103] The determination result, that is, whether the first member 91 and the second member 92 are successfully fitted together or not, is stored in the storage unit 32.

[0104] Furthermore, whether the above criteria are satisfied for each of the sensors 4A to 4H may be tallied and stored in the memory unit 32. In this case, it is possible to know which of the sensors 4A to 4H satisfied the criteria, and therefore which of the mating portions 9A to 9H were successful or unsuccessful in mating. Note that, for example, in the case of criterion (1), "satisfying the criteria" means that the reaction force (reaction force FA1 or reaction force FB1) at the peak of the reaction force change over time is equal to or greater than the first threshold value FS1.

[0105] In this embodiment, the mating state is determined for all mating portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, but the present invention is not limited thereto. For example, one or more mating portions, such as mating portions 9A, 9C, 9E, and 9G, can be selected from mating portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, and the mating state of only the selected mating portions can be determined using the same method as described above. Based on the results of these determinations, the success or failure of the mating of the first member 91 and the second member 92 can be determined. In this case, the mating portions to be selected and their number are not particularly limited. However, it is preferable to select the mating portions so that the arrangement of the selected mating portions is as uniform as possible in a plan view of the first member 91 and the second member 92. It is also preferable to select mating portions that account for 30% to 75% of the total number of mating portions.

[0106] When it is determined that the fitting of the first member 91 and the second member 92 is successful in the predetermined work object 9 (step S102: YES), the fact that the fitting is successful is stored in the storage unit 32 (step S103).

[0107] On the other hand, if it is determined that the fitting of the first member 91 and the second member 92 has failed (step S102: NO), the fact that the fitting has failed is stored in the storage unit 32 (step S104). At this time, which of the fitting portions 9A to 9H has failed to fit is also stored.

[0108] The work object 9 is provided with object identification information that identifies the work object 9 and is composed of, for example, numbers, symbols, marks, bar codes, two-dimensional codes, and other indicators, and the result of determining whether the fitting is successful or unsuccessful is linked to the object identification information and stored in the memory unit 32.

[0109] For example, the worker can read out the determination result stored in the memory unit 32, check it, and identify the work object 9 for which the fitting has failed based on the object identification information. Furthermore, the worker can easily and accurately take measures such as removing the foreign matter trapped between the first member 91 and the second member 92 from the identified work object 9, or discarding the work object 9 itself.

[0110] As described above, the robot control method is a method for controlling a robot that performs a fitting operation to fit a first member 91 having a plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G and 911H with a second member 92 having a plurality of second fitting portions 921A, 921B, 921C, 921D, 921E, 921F, 921G and 921H that fit with the plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G and 911H, respectively. The robot 1 comprises a robot arm 10 in which a plurality of arms (first arm 12 to sixth arm 17) are rotatably connected via joints (first joint 171 to sixth joint 176), a pressing member 40 provided at the tip of the robot arm 10 and pressing the first member 91 and the second member 92, and a plurality of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H provided at positions corresponding to a plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G and 911H of the pressing member 40, respectively, and for detecting reaction forces generated by the fitting operation. The robot control method also includes step S101, which is a pressing step in which the pressing member 40 presses the first member 91 and the second member 92 by driving the robot arm 10 so that the plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G, and 911H and the plurality of second fitting portions 921A, 921B, 921C, 921D, 921E, 921F, 921G, and 921H are fitted together, and the reaction force is detected by sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H; and step S102, which is a determination step in which the fitting state of the first member 91 and the second member 92 is determined based on the detection values ​​of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H. The sensors 4A to 4H are provided at positions on the pressing member 40 corresponding to the first fitting portions 911A to 911H, respectively, so that the reaction force generated when the fitting portions are fitted can be detected by the sensors 4A to 4H, respectively.This makes it possible to easily and accurately determine whether the first member 91 and the second member 92 are successfully or unsuccessfully fitted with a simple configuration, and in the case of multiple fitting portions, it is easy to know which fitting portion has failed to fit, allowing subsequent measures to be taken quickly and accurately.

[0111] The robot control method is a method for controlling a robot that performs a fitting operation of fitting a first member 91 having an annular first fitting portion and a second member 92 having an annular second fitting portion that fits with the first fitting portion. The robot 1 includes a robot arm 10 in which a plurality of arms (first arm 12 to sixth arm 17) are rotatably connected via joints (first joint 171 to sixth joint 176), a pressing member 40 that is provided at the tip of the robot arm 10 and presses the first member 91 and the second member 92, and a plurality of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H that are provided at positions of the pressing member 40 corresponding to the first fitting portions and that detect reaction forces generated by the fitting operation, and The method includes a pressing step S101 in which the pressing member 40 presses the first member 91 and the second member 92 by driving the robot arm 10 so that the first fitting portion and the second fitting portion fit together, and the sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H detect a reaction force, and a determination step S102 in which the fitted state of the first member 91 and the second member 92 is determined based on the detected values ​​of the sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H. The sensors 4A to 4H are provided at positions on the pressing member 40 that correspond to different positions of the annular first fitting portion, so that the reaction force generated when the fitting portions fit together can be detected by each of the sensors 4A to 4H. Therefore, with a simple configuration, it is possible to easily and accurately determine whether the first member 91 and the second member 92 are successfully or unsuccessfully fitted together, and it is also possible to easily determine which part of the annular fitting portion has failed to fit together, thereby enabling subsequent measures to be taken quickly and accurately.

[0112] When the workpiece 9 has an annular fitting portion, i.e., a fitting portion with a large area, using a conventional force sensor makes it possible to determine whether the fitting was successful or unsuccessful, but it is not possible to detect at which point on the fitting portion the fitting has failed. In contrast, in the above embodiment, multiple sensors are placed at locations where they can detect the reaction force generated when the annular fitting portion is fitted, making it possible to detect at which point on the annular fitting portion the fitting has failed.

[0113] The sensors 4A to 4H are preferably arranged at equal intervals in a circular pattern. Note that the circular fitting portion is only required to be ring-shaped, and may be round or have corners.

[0114] In the above embodiment, eight fitting portions 9A-9H are provided on the first member 91 and the second member 92, and thus eight sensors are provided. However, the present invention is not limited to this. The number, shape, structure, arrangement, size, etc., of the fitting portions of the workpiece 9 may be any number, and the type, function, performance, arrangement, etc. of the sensors can be appropriately set and selected accordingly. The number of sensors to be installed can be appropriately set and selected as long as there are more than one. Furthermore, the type, function, performance, number, and arrangement of sensors can be changed, for example, by replacing or adding sensors, depending on various conditions such as the number, shape, structure, arrangement, and size of the fitting portions. This makes it possible to easily and accurately determine the fitting state of each fitting portion depending on the purpose, type, shape, size, etc. of the workpiece 9. Therefore, the present invention is highly versatile.

[0115] In this embodiment, the control unit 31 of the control device 3 executes the robot control method of the present invention, but the present invention is not limited to this, and the configuration may be such that the method is executed by a control device other than the control device 3, for example, a control unit possessed by a teaching device, or the configuration may be such that these perform the same role.

[0116] In step S101, which is the pressing step, the reaction force is detected over time by the sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H, and in step S102, which is the determination step, the mated state is determined based on the change in the detected value over time, for example, as shown in Fig. 6. This makes it possible to more easily and accurately determine the mated state.

[0117] In the determination step (step S102), the mated state may be determined based on the magnitude of the detection value at a predetermined time.

[0118] In step S102, which is a determination step, if the amount of change in reaction force per unit time in all of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H in the change in detection value over time is equal to or greater than a predetermined value, it is determined that the mating is successful, and if the amount of change in reaction force per unit time in at least one of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H is less than the predetermined value, it is determined that the mating is unsuccessful. This makes it possible to more easily, accurately, and strictly determine the mating state.

[0119] Here, "the change in reaction force per unit time is greater than or equal to a predetermined value" means that the rate of increase in reaction force up to the peak of reaction force in judgment criterion (4) is greater than or equal to the fourth threshold, or that the absolute value of the rate of decrease in reaction force after the peak of reaction force in judgment criterion (5) is greater than or equal to the fifth threshold, and "the change in reaction force per unit time is less than a predetermined value" means that the rate of increase in reaction force up to the peak of reaction force in judgment criterion (4) is less than the fourth threshold, or that the absolute value of the rate of decrease in reaction force after the peak of reaction force in judgment criterion (5) is less than the fifth threshold.

[0120] In step S102, which is a determination step, the mated state is determined based on the reaction force FA1 or FB1, which is the maximum reaction force in the change over time of the detected value. This makes it possible to more easily and accurately determine the mated state.

[0121] More specifically, as described in the above judgment criterion (1), in the change over time of the detection value shown in FIG. 6, if the peak of the reaction force is equal to or greater than the first threshold value FS1, such as peak PA, it is judged that the mating is successful, and if the peak of the reaction force is less than the first threshold value FS1, such as peak PB, it is judged that the mating is unsuccessful.

[0122] In step S102, which is a determination step, the mated state is determined based on reaction force FA2 or FB2, which is the magnitude of the reaction force after the reaction force decreases from its maximum value and converges in the change in the detection value over time. This makes it possible to more easily and accurately determine the mated state.

[0123] More specifically, as described in the above judgment criterion (2), in the change over time of the detection value shown in FIG. 6, if the reaction force decreases from its peak and converges, and the reaction force FA2 or FB2 is equal to or less than the second threshold value FS2, it is judged that the mating is successful, and if the reaction force FA2 or FB2 exceeds the second threshold value FS2, it is judged that the mating is unsuccessful.

[0124] The fitting jig 4 is configured to fit the first member 91 having the plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G, and 911H, and the second member 92 having the plurality of second fitting portions 921A, 921B, 921C, 921D, 921E, 921F, 921G, and 921H that fit with the plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G, and 911H, respectively, to the robot arm 10. The robot 1, which performs a fitting operation by being driven, is equipped with a pressing member 40 attached to the tip of a robot arm 10 and which presses a first member 91 and a second member 92, and a plurality of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H which are provided at positions corresponding to a plurality of first fitting portions 911A, 911B, 911C, 911D, 911E, 911F, 911G and 911H of the pressing member 40 and which detect reaction forces generated by the fitting operation. Because the sensors 4A to 4H are provided at positions corresponding to the respective first fitting portions 911A to 911H of the pressing member 40, the reaction forces generated when the fitting portions are fitted can be detected by the respective sensors 4A to 4H. By using such a fitting jig 4 to determine whether the first member 91 and the second member 92 are successfully fitted or not based on the detection values ​​of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H, the determination can be made easily and accurately with a simple configuration, and in the case of multiple fitting portions, it is easy to know which fitting portion has failed to fit. Therefore, subsequent measures can be taken quickly and accurately.

[0125] Furthermore, the fitting jig 4 has the advantages of being simpler in configuration, lighter in weight, and easier to attach and detach from the robot arm 10 than conventional force detection units. This reduces the inertial weight of the tip of the robot arm 10 when driving the robot arm 10, thereby increasing the driving speed of the robot arm 10 and contributing to improved positional accuracy. This allows the fitting work to be performed more appropriately and quickly.

[0126] Next, variations in the measures to be taken after determining that the mating has failed in step S102 will be described.

[0127] (Pattern 1) If it is determined in step S102 that the fitting has failed, the result is stored in step S104, and a notification to that effect is made (notification step). This notification may be configured to display a notification screen on a display device (not shown), or may be made by sound, vibration, light, or a combination of these.

[0128] In the notification step, a sensor that does not satisfy the above criteria among sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H is notified, thereby enabling the worker to know which part corresponding to which sensor is not fitted.

[0129] In this way, the robot control method includes a notification step of notifying the operator of a mating failure when the determination step determines that the mating has failed, thereby enabling the operator to understand that the mating has failed.

[0130] (Pattern 2) If it is determined in step S102 that the fitting has failed, this is stored in step S104, and the robot arm 10 is driven to move the first member 91 and the second member 92 for which the fitting has failed to a location separate from the first member 91 and the second member 92 for which the fitting has been determined to have been successful. This allows the first member 91 and the second member 92 for which the fitting has failed to be managed in a location separate from the first member 91 and the second member 92 for which the fitting has been determined to have been successful. This makes it possible to prevent the first member 91 and the second member 92 for which the fitting has failed from being mixed with the first member 91 and the second member 92 for which the fitting has been determined to have been successful.

[0131] (Pattern 3) If it is determined in step S102 that the mating has failed, the result is stored in step S104, and the robot arm 10 is driven so that the load applied to the area corresponding to the sensor where the change in the detected reaction force is less than a predetermined value is greater than the load applied to the area corresponding to the sensor where the change in the detected reaction force is equal to or greater than the predetermined value. This allows the mating portion where the mating has failed to be pressed again with a stronger force to achieve successful mating. For example, a sensor whose detection value does not satisfy the above-mentioned criteria is a sensor whose detected change in reaction force is less than a predetermined value, and a sensor whose detection value satisfies the above-mentioned criteria is a sensor whose detected change in reaction force is equal to or greater than the predetermined value.

[0132] The pressing force when pressing again may be a preset value, or may be set according to the reaction force detected by the sensor 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H whose detection value does not satisfy the above judgment criteria.

[0133] Note that the pressing force may be increased until the mating is successful, and if it is determined that the mating has failed again, the control may be switched to the above (Pattern 1) or (Pattern 2).

[0134] (Pattern 4) If it is determined in step S102 that the fitting has failed, this is stored in step S104, and the pressing member 40 is moved in the direction opposite to the pressing direction, and then the robot arm 10 is driven to move in the pressing direction. This makes it possible to press the first member 91 and the second member 92 again, for which it has been determined that the fitting has failed. In particular, after moving the pressing member 40 in the direction opposite to the pressing direction, the operator can change the posture of the first member 91 and the second member 92 or remove any foreign matter present between the first member 91 and the second member 92, which can make it easier to determine that the fitting has succeeded after pressing again.

[0135] Although the robot control method and fitting jig of the present invention have been described in the illustrated embodiments, the present invention is not limited to these. Furthermore, each process and each part of the robot control method and fitting jig can be replaced with any process or structure that can perform the same function. Furthermore, any process or structure may be added.

[0136] Alternatively, a force sensor may be disposed at the tip of the robot arm 10, and the pressing member 40 may be attached to the force sensor. The force detection sensor is, for example, a sensor capable of detecting six-axis components of an external force applied to the robot arm 10. In this case, the detection value of the force sensor is used to perform tracking control to move the first fitting portion 911A of the first member 91 to a position corresponding to the second fitting portion 921A of the second member, and sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H may be used to determine the mating state during the mating operation. Note that if the combined detection values ​​of sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H of the mating jig 4 roughly match the detection values ​​of the force detection device, the mating operation may be performed using only sensors 4A, 4B, 4C, 4D, 4E, 4F, 4G, and 4H without the force detection device.

[0137] The robot system 100 may also include a camera. Based on the image captured by the camera, the robot arm 10 may be controlled to place the sensors 4A, 4B, 4C, 4D, 4E, 4F, and 4G at positions corresponding to the fitting portions 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H, respectively. [Explanation of symbols]

[0138] 1...robot, 3...control device, 4...fitting jig, 4A...sensor, 4B...sensor, 4C...sensor, 4D...sensor, 4E...sensor, 4F...sensor, 4G...sensor, 4H...sensor, 9...work object, 9A...fitting portion, 9B...fitting portion, 9C...fitting portion, 9D...fitting portion, 9E...fitting portion, 9F...fitting portion, 9G...fitting portion, 9H...fitting portion, 10...robot arm, 11...base, 12...first arm, 13...second arm, 14...third arm, 1 5...fourth arm, 16...fifth arm, 17...sixth arm, 31...control unit, 32...storage unit, 33...communication unit, 40...pressure member, 40A...first pressure plate, 40B...second pressure plate, 91...first member, 92...second member, 100...robot system, 171...first joint, 172...second joint, 173...third joint, 174...fourth joint, 175...fifth joint, 176...sixth joint, 911A...first fitting portion, 911B...first fitting portion, 911C...first fitting portion, 911D ...first fitting portion, 911E...first fitting portion, 911F...first fitting portion, 911G...first fitting portion, 911H...first fitting portion, 921A...second fitting portion, 921B...second fitting portion, 921C...second fitting portion, 921D...second fitting portion, 921E...second fitting portion, 921F...second fitting portion, 921G...second fitting portion, 921H...second fitting portion, D1...motor driver, D2...motor driver, D3...motor driver, D4...motor driver, D5... Motor driver, D6...motor driver, E1...encoder, E2...encoder, E3...encoder, E4...encoder, E5...encoder, E6...encoder, F...arrow, FA1...reaction force, FA2...reaction force, FB1...reaction force, FB2...reaction force, FS1...first threshold, FS2...second threshold, M1...motor, M2...motor, M3...motor, M4...motor, M5...motor, M6...motor, PA...peak, PB...peak

Claims

1. A method for controlling a robot that performs a fitting operation of fitting a first member having a plurality of first fitting portions with a second member having a plurality of second fitting portions that respectively fit with the plurality of first fitting portions, the method comprising: The robot a robot arm in which a plurality of arms are rotatably connected via joints; a pressing member provided at a tip end of the robot arm and configured to press the first member and the second member; a plurality of sensors provided on the pressing member at positions corresponding to the plurality of first fitting portions, the sensors detecting a reaction force generated by the fitting operation; a pressing step in which the robot arm is driven to press the first member and the second member with the pressing member so that the plurality of first fitting portions and the plurality of second fitting portions are fitted together, and the reaction force is detected by each of the sensors; a determining step of determining a fitted state of the first member and the second member based on the detection values ​​of the sensors.

2. In the pressing step, the reaction force is detected over time by the sensors; 2. The robot control method according to claim 1, wherein the determining step determines the mating state based on a change over time in the detected value.

3. In the determination step, the change over time of the detected value is determining that the mating is successful when the amount of change in the reaction force per unit time in all of the plurality of sensors is equal to or greater than a predetermined value; 3. The robot control method according to claim 2, wherein if the amount of change in the reaction force per unit time in at least one of the plurality of sensors is less than the predetermined value, it is determined that the fitting has failed.

4. 4. The robot control method according to claim 2, wherein the determining step determines the mated state based on a maximum value of the reaction force in the change over time of the detected value.

5. 4. A robot control method according to claim 2 or 3, wherein the determination step determines the mating state based on the magnitude of the reaction force after the reaction force decreases from its maximum value and converges in the change over time of the detection value.

6. 4. The robot control method according to claim 2, further comprising a notifying step of notifying the failure of the fitting when the failure of the fitting is determined in the determining step.

7. 4. The robot control method according to claim 2, wherein, if it is determined that the fitting has failed in the determination step, the robot arm is driven to move the first member and the second member determined that the fitting has failed to a location different from the first member and the second member determined that the fitting has succeeded.

8. 4. A robot control method according to claim 3, wherein, if it is determined in the determination step that the engagement has failed, the robot arm is driven so that the load applied to the area corresponding to the sensor where the change in the detected reaction force has become less than a predetermined value is greater than the load applied to the area corresponding to the sensor where the change in the detected reaction force has become equal to or greater than the predetermined value.

9. 4. The robot control method according to claim 2, wherein if it is determined in the determination step that the fitting has failed, the pressing member is moved in a direction opposite to the pressing direction, and then the robot arm is driven to move in the pressing direction.

10. A method for controlling a robot that performs a fitting operation of fitting a first member having an annular first fitting portion with a second member having an annular second fitting portion that fits with the first fitting portion, the method comprising: The robot a robot arm in which a plurality of arms are rotatably connected via joints; a pressing member provided at a tip end of the robot arm and configured to press the first member and the second member; a plurality of sensors provided on the pressing member at positions corresponding to the first fitting portion, the sensors detecting a reaction force generated by the fitting operation; a pressing step of pressing the first member and the second member with the pressing member by driving the robot arm so that the first fitting portion and the second fitting portion fit together, and detecting the reaction force with each of the sensors; a determining step of determining a fitted state of the first member and the second member based on the detection values ​​of the sensors.

11. a pressing member attached to a tip end of a robot arm of a robot that performs a fitting operation of fitting a first member having a plurality of first fitting portions and a second member having a plurality of second fitting portions that respectively fit with the plurality of first fitting portions by driving the robot arm, and that presses the first member and the second member; a plurality of sensors provided on the pressing member at positions corresponding to the plurality of first fitting portions, the sensors detecting reaction forces generated by the fitting operation.

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