JP7154748B2 - ROBOT SYSTEM, PRODUCT MANUFACTURING METHOD, CONTROL METHOD, CONTROL PROGRAM, AND RECORDING MEDIUM - Google Patents

Description

The present invention relates to an assembly robot system , and an article manufacturing method, control method, control program, and recording medium using a robot device.

In recent years, the number of cases where assembly is performed by robots is increasing. For assembly robots, it is important to achieve both precision and high-speed operation. However, in robots, a transmission mechanism such as a speed reducer or a ball screw is often arranged between a load and a power source, and the transmission mechanism hinders precise assembly. For example, the transmission mechanism is subject to angular errors due to torsion and meshing of reduction gear teeth, backlash, friction, minute vibrations of small parts, angular errors due to ball screw deformation, screw resonance, lost motion, and the like. When the power source is operated, thrust is transmitted to the load through the transmission mechanism, and the load can be driven. However, since the transmission mechanism is softer than the structure represented by the link of the robot arm, it twists and behaves like a spring. This causes the load to undergo simple harmonic motion with respect to the power source, resulting in a loss of precision. In addition, if a reaction force of simple harmonic motion acts on the power source, the position of the power source is displaced, further resulting in loss of precision.

Therefore, in Patent Document 1, when the second part is brought into contact with the first part, the movement direction and the movement amount of the second part are calculated from the force that the second part receives from the first part, and the position of the second part is calculated. It is suggested that a match should be made.

Japanese Patent No. 3288518

However, in the method described in Patent Document 1, there are cases where the calculated movement amount is less than the motion resolution of the robot arm. was difficult to do. That is, even if the second part is moved by the calculated movement amount, the second part may move more than the movement amount due to the motion resolution of the robot arm. Therefore, it has been necessary to perform the fitting several times and expect that the fitting will occur by chance, and it has been impossible to perform precise fitting, or it has taken a long time to complete the fitting.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to fit a fitting member to a shaft member at high speed and with precision.

According to one aspect of the present invention, a robot system includes a robot main body that brings a fitting member having an inner peripheral surface into contact with a shaft member that has a side surface that contacts the inner peripheral surface, and a control unit that controls the robot main body. and wherein the control unit causes the robot main body to bring the fitting member into contact with the shaft member in an inclined state, and with the fitting member in contact with the shaft member, the By controlling the fitting member to move in a first direction in which the fitting member is assembled to the shaft member and to move in a second direction perpendicular to the first direction, generating a moment that changes the posture of the fitting member such that the centers of the fitting member and the shaft member coincide and the inner peripheral surface and the side surface follow each other ; It is characterized in that the peripheral surface conforms to the side surface.

ADVANTAGE OF THE INVENTION According to this invention, a fitting member can be fitted to a shaft member at high speed and precisely.

1 is a perspective view of a robot device according to a first embodiment; FIG. 1 is a block diagram showing the configuration of a robot control device according to a first embodiment; FIG. 3 is a control block diagram showing the control system of the robot device according to the first embodiment; FIG. 4 is a flow chart when force-controlling the robot in the first embodiment. 4 is a flow chart for position control of the robot in the first embodiment. It is a schematic diagram of the robot in 1st Embodiment. 4 is a flow chart showing steps of a manufacturing method for manufacturing an assembly in the first embodiment; (a) to (c) are explanatory diagrams showing the positional relationship between the bearing and the shaft in each step of the manufacturing method for manufacturing the assembly in the first embodiment. (a) to (c) are explanatory diagrams showing the positional relationship between the bearing and the shaft in each step of the manufacturing method for manufacturing the assembly in the first embodiment. 4 is a profile of forces detected in the first embodiment; (a) to (c) are explanatory diagrams showing the positional relationship between the bearing and the shaft in the searching process according to the second embodiment. 10 is a profile of forces detected in the second embodiment; (a) is a sectional view showing a positional relationship between a bearing to be assembled and a shaft according to a third embodiment. (b) is a cross-sectional view showing a positional relationship between a bearing and a shaft of a reference example; (c) is a top view of a bearing and a shaft of a reference example. (a) is a sectional view showing a positional relationship between a bearing to be assembled and a shaft according to a modification of the third embodiment. (b) is a cross-sectional view showing a positional relationship between a bearing and a shaft of a reference example; It is a flow chart which shows pressing processing in a 4th embodiment. (a) and (b) are profiles of pressing force measured in the fourth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[First embodiment]
FIG. 1 is a perspective view of a robot device 100 according to the first embodiment. As shown in FIG. 1, the robot apparatus 100 includes a robot 200 that is a manipulator, and a robot controller 300 that is an example of a control section that controls the operation of the robot 200 . The robot device 100 also includes a teaching pendant (TP) 400 as a teaching device that transmits teaching data to the robot control device 300 . The TP 400 is operated by the operator, and is used to specify the motion of the robot 200 and the robot control device 300 .

The robot 200 includes a vertically articulated robot arm 251 and a robot hand 252 that is an example of an end effector attached to the tip of the robot arm 251 . A proximal end of the robot arm 251 is fixed to the pedestal 150 . The robot hand 252 grips an object (work) such as a part or a tool.

The robot arm 251 has multiple joints, eg, six joints J ₁ to J ₆ . The robot arm 251 has a plurality of, for example, six servo motors 201 to 206 that rotationally drive the joints J ₁ to J ₆ about the joint axes A ₁ to A ₆ . The robot arm 251 has a plurality of links 210 ₀ to 210 ₆ rotatably connected at joints J ₁ to J ₆ . Here, the links 210 ₀ to 210 ₆ are serially connected in order from the proximal side to the distal side. The robot arm 251 can orient the hand of the robot 200 (the tip of the robot arm 251) in any three-dimensional position and any three orientations within the movable range. Although a case where the joints of the robot arm 251 are rotary joints will be described, the joints may be prismatic joints. "Joint position" indicates the rotational position (that is, angle) of the joint if the joint is a revolute joint, and indicates the translational position of the joint if the joint is a prismatic joint.

The position and posture of the hand of the robot 200 are represented by a coordinate system To based on the base end of the robot arm 251, that is, the pedestal 150. As shown in FIG. A coordinate system Te is set at the hand of the robot 200 . Here, the tip of the robot 200 is the robot hand 252 when the robot hand 252 does not grip an object. When the robot hand 252 is gripping an object, the hand of the robot 200 includes the robot hand 252 and the gripped object. In other words, regardless of whether the robot hand 252 is gripping an object or not gripping an object, the tip of the robot arm 251 is referred to as the tip.

The servomotors 201-206 have electric motors 211-216 that drive the joints J1 _{- J6} , respectively, and sensor units 221-226 that are connected to the electric motors 211-216, respectively. Each of the sensor units 221-226 has a position sensor that generates a signal corresponding to the position, ie angle, of each joint J1 _{- J6} . Further, each of the sensor units 221-226 has a torque sensor that generates a signal corresponding to the torque of each joint J1 _{- J6} . Each of the servo motors 201 to 206 is connected to links driven by the joints J ₁ to J ₆ via transmission mechanisms (not shown) such as reduction gears, belts and bearings.

The robot control device 300 has a servo control section 230 that controls driving of the electric motors 211-216 of the servo motors 201-206. The servo control unit 230 supplies current to the electric motors 211 to 216 based on the torque command values corresponding to the joints J ₁ to J ₆ so that the torques of the joints J ₁ to J ₆ follow the torque command values. and controls the driving of the electric motors 211-216. In the first embodiment, the servo control unit 230 is arranged inside the housing of the robot control device 300, but is not limited to this. may be placed inside the Further, torque is generated in the rotary joints, but thrust is generated in the prismatic joints. The torque of the rotary joint and the thrust of the prismatic joint are collectively referred to as the "thrust of the joint".

Next, the robot control device 300 will be described. FIG. 2 is a block diagram showing the configuration of the robot control device 300 according to the first embodiment. The robot control device 300 is configured by a computer and includes a CPU (Central Processing Unit) 301 as a processing section. The robot control device 300 also includes a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, and a HDD (Hard Disk Drive) 304 as storage units. The robot controller 300 also includes a recording disk drive 305 and various interfaces 306-309.

The CPU 301, ROM 302, RAM 303, HDD 304, recording disk drive 305, and interfaces 306-309 are connected via a bus 310 so as to be able to communicate with each other. The CPU 301 performs arithmetic processing and control processing according to the program 330 . The ROM 302 stores basic programs such as BIOS. A RAM 303 is a storage device that temporarily stores various data such as the result of arithmetic processing by the CPU 301 . The HDD 304 is a storage device for storing arithmetic processing results of the CPU 301 and various data obtained from the outside, and records a program 330 for causing the CPU 301 to execute arithmetic processing and control processing. The recording disk drive 305 can read various data and programs recorded on the recording disk 331 .

TP 400 is connected to interface 306 . The CPU 301 receives teaching data input from the TP 400 via the interface 306 and the bus 310 and stores it in the HDD 304 . Servo controller 230 is connected to interface 309 . The CPU 301 acquires detection results (signals) from the sensor units 221 to 226 (FIG. 1) of the servo motors 201 to 206 via the servo control unit 230 . It should be noted that the CPU 301 may be configured to directly obtain the detection result from each of the sensor units 221 to 226 without going through the servo control unit 230 . A monitor 321 is connected to the interface 307 , and various images are displayed on the monitor 321 under the control of the CPU 301 . The interface 308 is configured to be connectable with an external storage device 322 such as a rewritable non-volatile memory or an external HDD.

In the first embodiment, the HDD 304 is the computer-readable recording medium, and the HDD 304 stores the program 330. However, the present invention is not limited to this. The program 330 may be recorded on any computer-readable recording medium. For example, as a recording medium for supplying the program 330, the ROM 302, the recording disk 331, the external storage device 322, etc. shown in FIG. 2 may be used. As a specific example, a flexible disk, a hard disk, an optical disk such as a DVD-ROM or a CD-ROM, a magneto-optical disk, a magnetic tape, a non-volatile memory, or the like can be used as the recording medium.

FIG. 3 is a control block diagram showing the control system of the robot device 100 according to the first embodiment. Each sensor section 221-226 has a torque sensor 541-546 and a position sensor 551-556. Position sensors 551 to 556 respectively detect positions (angles) q ₁ to q ₆ of joints J ₁ to J ₆ and output (feed back) signals indicating the positions q ₁ to q ₆ to the robot controller 300. It is composed of, for example, a rotary encoder.

Each torque sensor 541 to 546 detects the torque (thrust force) τ ₁ to τ ₆ of each joint J ₁ to J ₆ and outputs (feeds back) a signal indicating the torque τ ₁ to τ ₆ to the robot control device 300. . The plurality of torque sensors 541 to 546 and the plurality of position sensors 551 to 556, that is, the plurality of sensor portions 221 to 226 constitute the sensor 540. FIG.

The CPU 301 of the robot control device 300 functions as a force detector 504 , a force controller 505 , a position command generator 506 and a commander 1100 by executing the program 330 . The servo control unit 230 includes a plurality (six because there are six joints) switching control units 511 to 516, a plurality (six because there are six joints) of position control units 521 to 526, and a plurality (six joints). Therefore, it has six motor control units 531 to 536 .

The HDD 304 stores force teaching data 501 and position teaching data 502 set by the operator using the TP 400 . The HDD 304 also stores work shape data 1200 associated with the work type, and a robot model 503 that is shape data of the robot 200 .

The force detection unit 504 uses the robot model 503, the torques τ ₁ to τ ₆ detected by the torque sensors 541 to 546, and the positions q ₁ to q ₆ detected by the position sensors 551 to 556 to detect the force of the robot arm 251. A force F acting on the tip is calculated (detected). Here, the force F includes 6 parameters, 3 translational forces and 3 rotational forces (moment of force).

Command unit 1100 acquires force teaching data 501 , position teaching data 502 , shape data 1200 and robot model 503 stored in HDD 304 . The command unit 1100 outputs the force command value F _ref and the position command value P _ref to the force control unit 505 in the force control mode in which force control is performed, and generates the position command value P _ref in the position control mode in which position control is performed. Output to unit 506 . Like the force F, the force command value F _ref includes six parameters, three translational forces and three rotational forces (moment of force). The position command value P _ref includes six parameters indicating the position and orientation of the hand of the robot 200 , that is, the tip of the robot arm 251 .

The force control unit 505 uses the robot model 503, force command value F _ref , and force F to obtain torque command values τ _MFref1 to τ _MFref6 for each of the joints J ₁ to J ₆ . At this time, the torque command values τ _MFref1 to τ _MFref6 are obtained so that the force deviation between the force F acting on the tip of the robot arm 251 and the force command value F _ref becomes small. The force control unit 505 outputs the calculated torque command values τ _MFref1 to τ _MFref6 to the switching control units 511 to 516 .

The position command generation unit 506 obtains position command values (angle command values) q _ref1 to q _ref6 for each of the joints J ₁ to J ₆ from the position command value P _ref by inverse kinematics calculation, and calculates the position command values q _ref1 to q _ref6 is output to each of the position control units 521-526. Each of the position control units 521 to 526 controls the torque command values so that the deviations between the positions q ₁ to q ₆ of the joints J ₁ to J ₆ and the position command values q _ref1 to q _ref6 of the joints J ₁ to J ₆ are small. Obtain τ _MPref1 to τ _MPref6 . Position controllers 521-526 output torque command values τ _MPref1 -τ _MPref6 to switching controllers 511-516, respectively.

Each of the switching control units 511 to 516 switches to the force control mode when the torque command values τ _MFref1 to τ _MFref6 are acquired from the force control unit 505 . Further, each of the switching control units 511 to 516 performs switching control to the position control mode when each of the torque command values τ _MPref1 to τ _MPref6 is acquired from each of the position control units 521 to 526 . That is, the switching control units 511 to 516 output the torque command values τ _MFref1 to τ _MFref6 as the torque command values τ _Mref1 to τ _Mref6 to the motor control units 531 to 536 in the force control mode. In the position control mode, the switching control units 511 to 516 output the torque command values τ _MPref1 to τ _MPref6 as the torque command values τ _Mref1 to τ _Mref6 to the motor control units 531 to 536, respectively.

Based on the positions (angles) θ ₁ to θ ₆ of the electric motors 211 to 216, the motor control units 531 to 536 control the currents Cur ₁ to Cur ₆ so as to achieve the torque command values τ _Mref1 to τ _Mref6 . Electric motors 211 to 216 are energized.

Next, force control of the robot 200 will be described. FIG. 4 is a flow chart for force control of the robot 200 in the first embodiment. The command unit 1100 commands (outputs) the force command value F _ref and the position command value P _ref to the force control unit 505 (S11). The force command value F _ref is stored in force teaching data 501 and the position command value P _ref is stored in position teaching data 502 . This position command value P _ref is the position at which the force control operation is started.

The force control unit 505 calculates torque command values (forces) τ _MFref1 to τ _MFref6 for the electric motors 211 to 216 based on the robot model 503 so that the force F applied to the tip of the robot arm 251 follows the force command value F _ref . (S12).

The switching control units 511 to 516 output torque command values (force) τ _MFref1 to τ _MFref6 to the motor control units 531 to 536 as torque command values τ _Mref1 to τ _Mref6 (S13). The motor control units 531 to 536 perform energization control so as to realize the respective torque command values τ _Mref1 to τ _Mref6 based on the angles θ ₁ to θ ₆ of the electric motors 211 to 216 (S14). The electric motors 211 to 216 generate joint torques τ ₁ to τ ₆ at the joints J ₁ to J ₆ when energized (S15).

Position sensors 551 to 556 detect positions q ₁ to q ₆ of joints J ₁ to J ₆ (S16). Torque sensors 541 to 546 detect torques τ ₁ to τ ₆ of joints J ₁ to J ₆ (S17). The positions q ₁ to q ₆ of the joints J ₁ to J ₆ and the torques τ ₁ to τ ₆ of the joints J ₁ to J ₆ are fed back to the force detector 504 of the robot controller 300 .

Based on the robot model 503 and the positions q ₁ -q ₆ of the joints J ₁ -J ₆ , the force detection unit 504 detects the torques τ ₁ -τ ₆ of the joints J ₁ -J ₆ at the hand of the robot 200, that is, the robot. It is converted (calculated) into a force F applied to the tip of the arm 251 (S18). The angles θ ₁ to θ ₆ of the electric motors 211 to 216 may be used instead of the positions q ₁ to q ₆ of the joints J ₁ to J ₆ .

The CPU 301 determines whether or not the driving has ended (S19), and if it has not ended (S19: No), steps S12 to S18 are repeated. By driving the electric motors 211 to 216 according to the above flow, the force F applied to the tip of the robot arm 251 can be controlled to the force command value F _ref . Note that the order of the flow chart shown in FIG. 4 is not restrictive, and force control can be performed in other orders.

Next, position control of the robot 200 will be described. FIG. 5 is a flowchart for position control of the robot 200 in the first embodiment. First, the command unit 1100 commands (outputs) a position command value P _ref to the position command generation unit 506 (S21). The position command value P _ref is stored in position teaching data 502 .

The position command generator 506 calculates position command values q _ref1 to q _ref6 for the joints J ₁ to J ₆ from the position command value P _ref based on the robot model 503 (S22). The position control units 521 to 526 control the electric motors 211 to 216 so that the positions q ₁ to q ₆ of the joints J ₁ to J ₆ follow the position command values q _ref1 to q _ref6 of the joints J ₁ to J ₆ . Torque command values (position) τ _MPref1 to τ _MPref6 are calculated (S23). Angles θ ₁ to θ ₆ of the electric motors 211 to 216 may be used instead of the positions q ₁ to q ₆ as the signals indicating the positions of the joints J ₁ to J ₆ .

The switching control units 511 to 516 output torque command values (positions) τ _MPref1 to τ _MPref6 as torque command values τ _Mref1 to τ _Mref6 to the motor control units 531 to 536 (S24). The motor control units 531 to 536 perform energization control so as to realize the respective torque command values τ _Mref1 to τ _Mref6 based on the angles θ ₁ to θ ₆ of the electric motors 211 to 216 (S25). The electric motors 211 to 216 generate joint torques τ ₁ to τ ₆ at the joints J ₁ to J ₆ when energized (S26).

Position sensors 551 to 556 detect positions q ₁ to q ₆ of joints J ₁ to J ₆ (S27). The positions q ₁ -q ₆ of the joints J ₁ -J ₆ are fed back to the position controllers 521 - 526 of the robot controller 300 . The angles θ ₁ to θ ₆ of the electric motors 211 to 216 may be used instead of the positions q ₁ to q ₆ of the joints J ₁ to J ₆ .

The CPU 301 determines whether or not the driving has ended (S28), and if not (S28: No), repeats steps S23 to S27. By driving the electric motors 211 to 216 according to the above flow, it is possible to control the position P of the tip of the robot arm 251 to follow the position command value P _ref .

Force control in steps S11 to S19 and position control in steps S21 to S28 are switched by switching control units 511 to 516 according to commands from command unit 1100, and one of the controls is selected according to the work. .

FIG. 6 is a schematic diagram of the robot 200. As shown in FIG. In this embodiment, the robot 200 is caused to perform a fitting operation of fitting a bearing W1, which is an example of a fitting member that is a first work, to a shaft W2 that is an example of a shaft member that is a second work. . The bearing W1 is a ring-shaped member. In this embodiment, the bearing W1 is positioned and held by the holding jig 401 with high accuracy, and the shaft W2 is positioned and held by the holding jig 402 with high accuracy. By gripping the bearing W1 with the robot hand 252 and fitting it to the shaft W2, an assembly having the bearing W1 and the shaft W2 is manufactured.

The shaft W2 has a cylindrical side surface S2, a circular end surface F2, and an edge E2 that is a boundary between the side surface S2 and the end surface F2. The bearing W1 has a cylindrical inner surface S1 and an edge E1 formed at the lower end of the inner surface S1. The inner circumference C1 of the bearing W1 is composed of the inner surface S1 and the edge E1. When the bearing W1 is fitted on the shaft W2, the side surface S2 of the shaft W2 and the inner side surface S1 of the bearing W1 are engaged.

The method of manufacturing the assembly will be described in detail below. FIG. 7 is a flow chart showing steps of a manufacturing method for manufacturing an assembly. 8(a) to 8(c) and 9(a) to 9(c) are explanatory diagrams showing the positional relationship between the bearing W1 and the shaft W2 in each step of the manufacturing method for manufacturing the assembly. be. 8(a) and 8(b) are sectional views of the bearing W1 and the shaft W2, and FIG. 8(c) is a top view of the bearing W1 and the shaft W2. 9(a) to 9(c) are sectional views of the bearing W1 and the shaft W2.

The control of the fitting operation is performed by the entire robot control device 300 shown in FIG. That is, the command unit 1100 selects position control and force control, commands a position command value P _ref in the position control and a force command value F _ref in the force control, and controls the motion of the robot 200 .

The command unit 1100 controls the posture of the robot arm 251 by position control so that the robot hand 252 moves to the position where it grips the bearing W1, and causes the robot hand 252 to grip the bearing W1 (S31: gripping process, first processing, first step).

At this time, as shown in FIG. 8A, the bearing W1 is positioned and held by the holding jig 401 with high accuracy, so that it is held by the robot hand 252 with high accuracy. For example, when the robot hand 252 grips the bearing W1, the center axis L0 of the robot hand 252 and the center axis L1 of the bearing W1 match with high accuracy.

The shaft W2 is positioned and held by a holding jig 402 with high accuracy. That is, the shaft W2 is positioned and held with high accuracy such that the axial direction Z in which the center axis L2 of the holding jig 402 extends is parallel to the vertical direction. Even if the bearing W1 and the shaft W2 are positioned with high accuracy in this way, it is difficult to perform the fitting operation of fitting the bearing W1 to the shaft W2 only by position control. That is, the bearing W1 supported by the robot 200 is slightly displaced with respect to the shaft W2 by the transmission mechanism included in the robot arm 251 or the like. Therefore, in this embodiment, the fitting operation is performed by switching between position control and force control.

Therefore, first, the command unit 1100 causes the robot hand 252 to grip the bearing W1 by position control so that the bearing W1 moves on the extension line of the central axis L2 of the shaft W2, that is, directly above the shaft W2. Control arm 251 .

At this time, the command unit 1100 controls the robot arm 251 so that the bearing W1 is tilted with respect to the axial direction Z in which the central axis L2 of the shaft W2 extends. That is, the command unit 1100 controls the robot arm 251 so that the central axis L1 of the bearing W1 is tilted with respect to the central axis L2 of the shaft W2. Then, the command unit 1100 controls the robot arm 251 to move the bearing W1 in the axial direction Z so that the bearing W1 approaches the shaft W2 by position control while the bearing W1 is tilted.

The inclination angle θ of the center axis L1 with respect to the center axis L2 is about 1 degree to 5 degrees. Then, after the bearing W1 contacts the shaft W2, the command unit 1100 switches to force control and controls the robot arm 251 so as to press the bearing W1 against the shaft W2 in the axial direction Z (S32: pressing process, second processing, second step). As a result, as shown in FIG. 8B, the bearing W1 is pressed against the shaft W2 in the axial direction Z with a force (pressing force) Fz.

FIG. 10 is a force profile detected in steps S32 to S35 of the first embodiment. When the bearing W1 contacts the shaft W2, the pressing force Fz in the axial direction Z among the forces F obtained by the force detection unit 504 exceeds the threshold value _Fzth . When the pressing force Fz exceeds the threshold Fz _th , the command unit 1100 switches from position control to force control and controls the robot arm 251 so that the pressing force Fz approaches the threshold Fz _th . As a result, the bearing W1 is pressed against the shaft W2 in the axial direction Z with a predetermined force corresponding to the threshold value _Fzth .

Note that the command unit 1100 may control the robot arm 251 by position control so that the robot arm 251 moves to a position just before the position where the bearing W1 is pressed against the shaft W2. Then, the command unit 1100 may switch to force control, bring the bearing W1 into contact with the shaft W2 in the axial direction Z, and press it with a predetermined force that becomes the threshold value _Fzth while performing force control.

Next, the command unit 1100 controls the robot arm 251 by force control so that the forces Fx and Fz act on the bearing W1 as shown in FIGS. 8(c) and 9(a). That is, the command unit 1100 presses the bearing W1 against the shaft W2 in the radial direction Rx that presses the edge E1 of the inner circumference C1 of the bearing W1 against the side surface S2 of the shaft W2 while applying the pressing force Fz in the axial direction Z. , the robot arm 251 is controlled. The radial direction Rx is a direction perpendicular to the axial direction Z, and is a direction from the portion where the edge E1 contacts the side surface S2 toward the central axis L2 extending in the axial direction Z. As shown in FIG. The force applied in the radial direction Rx is referred to as a probing force Fx.

Since the bearing W1 is inclined with respect to the shaft W2, when the bearing W1 is viewed from above as shown in FIG. The shape becomes larger. Therefore, the bearing W1 comes into contact with the shaft W2 at three contact positions P1, P2 and P3. Specifically, the contact position P1 is the contact portion of the edge E1 of the bearing W1 with the side surface S2 of the shaft W2. In addition, on the edge E1 of the bearing W1, the contact positions P2 and P3 are the contact portions with the edge E2 of the shaft W2.

By applying the probing force Fx in the radial direction Rx while applying the pressing force Fz in the axial direction Z, the bearing W1 receives a reaction force from the shaft W2. The command unit 1100 controls the robot arm 251 so as to change the attitude of the bearing W1 in accordance with the rotational force M about the rotation axis L3 extending in the direction perpendicular to the axial direction Z, among the reaction forces received from the shaft W2 ( S33: Exploring process, third process, third step). The rotation axis L3 is a virtual line passing through the contact position P2 and the contact position P3, and its position changes according to the contact positions P2 and P3. Also, the rotational force M is a moment of force. Command unit 1100 acquires the value of force F from force detection unit 504 as the reaction force received from shaft W2. That is, the information (value) of the force F obtained from the force detection unit 504 includes information (value) of the reaction force received from the shaft W2. Command unit 1100 obtains the value of rotational force M from the value of force F. FIG.

The command unit 1100 operates the robot arm 251 so that the bearing W1 moves in the direction in which the rotational force M acts. As a result, the contact positions P2 and P3 and the rotation axis L3 move in a direction parallel to the radial direction Rx while the contact position P1 rises along the side surface S2 following the rotational force M around the rotation axis L3. As a result, the edge E1 of the bearing W1 shown in FIG. 8(c) gradually changes from an elliptical shape to a circular shape.

That is, as shown in FIG. 10, by applying the probing force Fx in step S33, a rotational force M is generated that causes the contact position P1 to rise. Then, when the attitude of the bearing W1 is changed according to the rotational force M and the central axis L1 and the central axis L2 coincide with each other, the contact positions P1, P2, and P3 disappear, and the rotational force M also disappears. At this time, as shown in FIG. 9B, the edge E1 of the bearing W1 and the edge E2 of the shaft W2 are brought into contact with each other.

Based on the value of the rotational force M, the command unit 1100 determines whether or not the bearing W1 has been positioned relative to the shaft W2 (S34). Continue processing. Specifically, the command unit 1100 operates the robot arm 251 by force control, and changes the attitude of the bearing W1 until the value of the rotational force M obtained from the signal from the sensor 540 falls below the threshold value _Mth . . When the value of the rotational force M falls below the threshold value _Mth , the command unit 1100 moves to the next step S35 because the positioning is completed. It should be noted that the determination as to whether or not the positioning has been completed may be made based on, for example, the amount of sinking of the bearing W1 and the posture information of the robot arm 251, in addition to the rotational force M.

When the positioning is completed (S34: Yes), the command unit 1100 causes the center axis L1 of the bearing W1 and the center axis L2 of the shaft W2 to match, so that force control causes the following to occur as shown in FIG. The bearing W1 is fitted to the shaft W2 (S35). Thereby, an assembly W0 having the bearing W1 and the shaft W2 is manufactured. In this fitting operation, the pressing force Fz acting on the bearing W1 may decrease at the timing when the bearing W1 is lowered.

By operating the robot 200 as described above, at the contact position P1 where the bearing W1 contacts the shaft W2, a rotational force M that causes the bearing W1 to rise is generated. By doing so, the rotational force M is relaxed. As a result, the so-called "biting" phenomenon can be avoided, and it is possible to fit the bearing W1 to the shaft W2 with high precision and high speed. Further, by performing the fitting operation while following the rotational force M of the bearing W1, high-speed and precise fitting operation can be performed regardless of the movement resolution of the robot arm 251. FIG.

[Second embodiment]
Next, a method for manufacturing an assembly by the robot device according to the second embodiment will be described. 11(a) to 11(c) are explanatory diagrams showing the positional relationship between the bearing W1 and the shaft W2 in the searching process according to the second embodiment. A schematic configuration of the robot apparatus is the same as that of the first embodiment. The control operation of the robot control device 300, that is, the command section 1100 is different from that of the first embodiment. Specifically, among steps S31 to S35 in FIG. 7, the searching process in step S33 is different from that in the first embodiment. The operation of step S33 in the second embodiment will be described in detail below.

In step S33, the command unit 1100 applies a searching force Fx in the radial direction Rx that presses the edge E1 of the bearing W1 against the side surface S2 of the shaft W2 to press the bearing W1 against the shaft W2. At the same time, in step S33, the command unit 1100 moves the bearing W1 in the radial direction Rx to the shaft W2 while moving the contact position P1 where the edge E1 of the bearing W1 contacts the side surface S2 of the shaft W2 in the circumferential direction R2 of the shaft W2. press against. That is, as shown in FIGS. 11(a) to 11(c), the contact position P1 is rotated (revolved) in the circumferential direction R2 around the central axis L2. The direction of the probing force Fx from the contact position P1 toward the center axis L2 also rotates.

FIG. 12 is a force profile detected in steps S32 to S35 of the second embodiment. In FIG. 12, the broken line indicates the rotational force M generated in the first embodiment, and the solid line indicates the rotational force M generated in the second embodiment. By adding the oscillating rotational motion to the bearing W1, as shown in FIG. 12, the rotational force M generated as a reaction force is reduced, and the bearing W1 can be fitted to the shaft W2 more smoothly than in the first embodiment. is possible.

[Third embodiment]
Next, a method for manufacturing an assembly by the robot device according to the third embodiment will be described. FIG. 13(a) is a sectional view showing the positional relationship between the bearing W1 to be assembled and the shaft W2 according to the third embodiment. 13(b) is a sectional view showing the positional relationship between the bearing W1 and the shaft W2 of the reference example, and FIG. 13(c) is a top view of the bearing W1 and the shaft W2 of the reference example.

As shown in FIG. 13(a), the side surface S2 of the shaft W2 has a cylindrical surface C2 and a concave surface D2 recessed from the cylindrical surface C2. This concave surface D2 is a D-cut surface.

When the side surface S2 of the shaft W2 is provided with the concave surface D2, the fitting may fail in the posture of the reference example shown in FIG. 13B. That is, when the concave surface D2 is a D-cut surface, if there is a contact position P1 on the D-cut surface, as shown in FIG. . Since the processed edge is sharp, there are times when the rising rotational force is not generated.

In the third embodiment, as shown in FIG. 3, shape data 1200 of the bearing W1 and the shaft W2 corresponding to the model is stored in the HDD 304 in advance. When the user operates the TP 400 to input the model, command unit 1100 reads the shape data of bearing W1 and shaft W2 corresponding to the model. Command unit 1100 obtains the attitude of bearing W1 based on the shape data of bearing W1 and shaft W2, and sets the attitude of bearing W1 in step S32. That is, in step S32, the command unit 1100 sets the posture of the bearing W1 that is inclined with respect to the axial direction Z according to the shapes of the bearing W1 and the shaft W2. In step S33, command unit 1100 presses edge E1 of bearing W1 against cylindrical surface C2.

Thus, in the third embodiment, since the concave surface D2 is a D-cut surface, the bearing W1 is tilted so that the contact position P1 does not come into contact with the D-cut surface as shown in FIG. 13(a). As a result, it is possible to reliably generate a rising force in the bearing W1, and it is possible to fit the bearing W1 to the shaft W2 at high speed and with high accuracy.

In addition, by providing the TP400 with an interface for selecting the type of the bearing W1 and the shaft W2, it becomes possible to quickly teach the fitting operation of the bearing W1, and fitting of a plurality of types of bearings W1 can be realized. Many processes can be realized by being able to handle a plurality of types of bearings W1 for assembly objects. For example, one copying machine can be assembled by one robot device, and the assembly system can be greatly miniaturized.

Although the case where the posture of the bearing W1 is obtained from the shape data of the bearing W1 and the shaft W2 corresponding to the model has been described, the present invention is not limited to this. For example, the posture data of the bearing W1 or the posture data of the robot arm 251 corresponding to the model may be stored in advance in the HDD 304, and the command section 1100 may read out and set the posture data by the input operation of the TP400. This reduces the computational load on the CPU 301 .

Also, the case where the user operates the TP 400 to input the types of the bearing W1 and the shaft W2 has been described, but the orientation of the bearing W1, that is, the orientation of the robot arm 251 may be directly set (instructed).

Moreover, although the case where the concave surface D2 is a D-cut surface has been described, the present invention is not limited to this. FIG. 14(a) is a sectional view showing the positional relationship between a bearing W1 to be assembled and a shaft W2 according to a modification of the third embodiment. FIG. 14(b) is a sectional view showing the positional relationship between the bearing W1 and the shaft W2 of the reference example.

As shown in FIG. 14(a), the concave surface D2 is a groove surface extending in the circumferential direction R2. When the concave surface D2 is a groove surface, if the inclination angle θ of the bearing W1 is too large, the contact position P1 is caught in the groove surface as shown in FIG. Gone. Therefore, in step S32, the command unit 1100 sets the inclination angle θ of the bearing W1 to a small amount, thereby avoiding the edge E1 of the bearing W1 from being caught on the concave surface D2 as shown in FIG. 14(a). can do.

[Fourth embodiment]
Next, a method for manufacturing an assembly by a robot device according to the fourth embodiment will be described. FIG. 15 is a flow chart showing pressing processing in the fourth embodiment. The schematic configuration of the robot apparatus is the same as in the first to third embodiments. The control operation of the robot control device 300, that is, the command section 1100 is different from that of the first to third embodiments.

In the third embodiment, the user operates the TP400 to input the model number to set the attitude of the bearing W1 in step S32, or the user directly sets the attitude of the bearing W1 by operating the TP400. explained. In the fourth embodiment, the user does not operate the TP 400 to set the attitude of the bearing W1. set. The pressing process in the fourth embodiment, that is, the process of step S32 in FIG. 7 will be specifically described below.

First, the command unit 1100 controls the robot arm 251 to press the bearing W1 tilted with respect to the shaft W2 against the shaft W2 (S41).

Next, the command unit 1100 measures the profile of the force F acting on the tip of the robot arm 251 generated when the bearing W1 is pressed against the shaft W2, and analyzes the contact state (S42). Specifically, command unit 1100 measures the profile of pressing force Fz of force F. FIG.

16(a) and 16(b) are profiles of the measured pressing force Fz. FIG. 16(a) is a profile of the pressing force Fz when the edge E1 of the bearing W1 contacts the cylindrical surface C2 of the shaft W2. FIG. 16(b) is a profile of the pressing force Fz when the edge E1 of the bearing W1 contacts the concave surface D2 of the shaft W2.

As shown in FIG. 16(b), when the edge E1 of the bearing W1 contacts the concave surface D2 of the shaft W2, that is, when the contact position P1 is on the concave surface D2, the amplitude of the pressing force Fz exceeds the predetermined range H and vibrates. target. Therefore, in step S43, command section 1100 determines whether contact position P1 is on concave surface D2, that is, whether the amplitude of pressing force Fz is within a predetermined range.

When the amplitude of the pressing force Fz exceeds the predetermined range H as shown in FIG. 16(b), the contact position P1 is on the concave surface D2 (S43: Yes). When the amplitude exceeds the predetermined range H, the command unit 1100 adjusts the attitude of the bearing W1 tilted with respect to the axial direction Z (S44), and presses the bearing W1 against the shaft W2 again (S41).

In this manner, the command unit 1100 operates until the amplitude of the pressing force Fz is within the predetermined range H as shown in FIG. (S43: No), the pressing operation is repeated. By repeating the above operation, the edge E1 of the bearing W1 comes into contact with the cylindrical surface C2 of the shaft W2. Then, the command unit 1100 performs step S33 in FIG.

As described above, in the fourth embodiment, the command unit 1100 executes steps S41 to S44 shown in FIG. 15 as the pressing process of step S32 shown in FIG. W1 can be tilted. Therefore, the bearing W1 can be reliably fitted to the shaft W2.

The present invention is not limited to the embodiments described above, and many modifications are possible within the technical concept of the present invention. Moreover, the effects described in the embodiments are merely enumerations of the most suitable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments.

In the above embodiment, the robot arm 251 has six joints, but the number of joints is not limited to six. For example, it may be a single-axis robot arm.

Also, in the above-described embodiment, the case where the robot arm is a vertically articulated robot arm has been described, but the present invention is not limited to this. The robot arm may be, for example, a horizontal articulated robot arm, a parallel link robot arm, an orthogonal robot, or various other robot arms.

Further, in the above-described embodiment, the case where the sensor 540 is composed of the plurality of torque sensors 541 to 546 and the plurality of position sensors 551 to 556 has been described, but the present invention is not limited to this. For example, between the robot arm 251 and the robot hand 252, a force sensor that detects six-axis forces may be arranged as a sensor.

Also, in the above-described embodiments, the case where the drive source is an electric motor has been described, but the drive source is not limited to this, and may be, for example, an artificial muscle or the like.

Also, in the above-described embodiments, a ring-shaped member (bearing) was described as an example of the fitting member, but the fitting member is not limited to this. The fitting member may have any shape as long as it has a shape that fits the shaft member, that is, a shape that has an inner peripheral surface that contacts the side surface of the shaft member. For example, the fitting member may be a C-shaped member obtained by cutting out a part of the ring, or may be a member having a recessed hole instead of a member having a through hole. . Further, the shaft member is not limited to a round shaft shape, and may be a shape having corners such as a square shaft.

DESCRIPTION OF SYMBOLS 100... Robot apparatus, 200... Robot, 251... Robot arm, 252... Robot hand, 300... Robot control apparatus (control part), W0... Assembly, W1... Bearing (fitting member), W2... Shaft (shaft member)

Claims (24)

a robot body that brings a fitting member having an inner peripheral surface into contact with a shaft member having a side surface that contacts the inner peripheral surface ;
A control unit that controls the robot body,
The control unit
By the robot body,
bringing the fitting member into contact with the shaft member in an inclined state;
In a state in which the fitting member is in contact with the shaft member, the fitting member is moved in a first direction in which the fitting member is assembled to the shaft member, and in a direction orthogonal to the first direction. By controlling the movement in the second direction, the posture of the fitting member is such that the centers of the fitting member and the shaft member are aligned, and the inner peripheral surface and the side surface generates a moment that is changed so that the inner peripheral surface follows the side surface ,
A robot system characterized by: The control unit
controlling the robot body to move the fitting member in the first direction and the second direction while changing the posture of the fitting member in the direction of the moment;
The robot system according to claim 1, characterized by: The control unit
The robot main body changes the posture of the fitting member in the direction of the moment and moves the fitting member while controlling the fitting member to move in the first direction and the second direction. rotating about the first direction;
3. The robot system according to claim 2, characterized in that: The direction of the moment is a direction in which the contact position between the fitting member and the shaft member rises with respect to the shaft member.
The robot system according to any one of claims 1 to 3, characterized in that: The first direction is a direction orthogonal to the surface on which the shaft member is placed,
The robot system according to any one of claims 1 to 4, characterized in that: The second direction and the third direction orthogonal to the first direction and the second direction are directions forming a surface extending in a direction parallel to the surface on which the shaft member is mounted . ,
The robot system according to any one of claims 1 to 5, characterized in that: The robot body further includes a sensor that outputs a signal corresponding to a force acting on a predetermined portion of the robot body,
The control unit
changing the posture of the fitting member by the robot body until the value of the signal from the sensor falls below a threshold;
4. The robot system according to claim 2 or 3, characterized in that: The control unit
The amplitude of the vibration of the signal from the sensor generated when the fitting member is brought into contact with the shaft member in a state in which the fitting member is tilted with respect to the shaft member by the robot main body is within a predetermined range. By repeating the operation of changing the posture of the fitting member and bringing the fitting member into contact with the shaft member until the fitting member is inclined with respect to the shaft member, the fitting is performed . setting the posture of the fitting member when the fitting member is brought into contact with the shaft member;
8. The robot system according to claim 7, characterized by: The control unit
According to the shapes of the fitting member and the shaft member, the posture of the fitting member when the fitting member is brought into contact with the shaft member in a state in which the fitting member is inclined with respect to the shaft member is adjusted. set,
The robot system according to any one of claims 1 to 7, characterized in that: A posture of the fitting member when the fitting member is brought into contact with the shaft member in a state in which the fitting member is inclined with respect to the shaft member can be set by the user.
The robot system according to any one of claims 1 to 7, characterized in that: When the user directly operates an operation terminal for operating the robot main body or the robot main body to bring the fitting member into contact with the shaft member while the fitting member is inclined with respect to the shaft member. can set the posture of the fitting member of
11. The robot system according to claim 10, characterized in that: The control unit
The fitting member is set according to the setting of the posture of the fitting member when the fitting member is brought into contact with the shaft member in a state in which the fitting member is inclined with respect to the shaft member. The fitting member is moved in the first direction and in the second direction while the fitting member is in contact with the shaft member . the moment is generated, the posture of the fitting member is changed based on the moment, and the inner peripheral surface of the fitting member is brought into contact with the side surface of the shaft member;
The robot system according to any one of claims 8 to 11, characterized in that: The side surface has a cylindrical surface and a concave surface that is recessed with respect to the cylindrical surface,
The control unit
The robot body presses the inner peripheral surface against the cylindrical surface,
The robot system according to any one of claims 1 to 12 , characterized in that: The concave surface is a D-cut surface or a groove surface extending in the circumferential direction,
The robot system according to claim 13 , characterized by: The side surface has a cylindrical surface and a concave surface that is recessed with respect to the cylindrical surface,
The concave surface is a D-cut surface,
The control unit
the fitting member is inclined so as to contact the shaft member so that the contact position between the fitting member and the shaft member does not lie on the D-cut surface;
The robot system according to any one of claims 1 to 12 , characterized in that: The control unit
When the fitting member is brought into contact with the shaft member in a state in which the fitting member is inclined with respect to the shaft member by the robot main body, the inner peripheral surface and the side surface are brought into contact at three positions. ,
The robot system according to any one of claims 1 to 15 , characterized in that: The control unit
By controlling the robot body to move the fitting member in the first direction and in the second direction while the fitting member is in contact with the shaft member. , the moment is generated, and based on the moment, the entire inner peripheral surface and the entire side surface are brought into contact;
17. The robot system according to claim 16 , characterized by: wherein the fitting member is a bearing and the shaft member is a shaft;
The robot system according to any one of claims 1 to 17 , characterized in that: The control unit displays on the display unit,
displaying an interface for selecting the type of bearing;
19. The robot system according to claim 18 , characterized by: The robot body has an end effector and a robot arm,
The control unit
holding the fitting member by the end effector and moving the end effector by the robot arm to bring the fitting member into contact with the shaft member;
The robot system according to any one of claims 1 to 19 , characterized in that: Manufacture of an article using a robot system comprising a robot main body that brings a fitting member having an inner peripheral surface into contact with a shaft member having a side surface that contacts the inner peripheral surface, and a control unit that controls the robot main body. A method for manufacturing an article that
The control unit
By the robot body,
bringing the fitting member into contact with the shaft member in an inclined state;
In a state in which the fitting member is in contact with the shaft member, the fitting member is moved in a first direction in which the fitting member is assembled to the shaft member, and in a direction orthogonal to the first direction. By controlling the movement in the second direction, the posture of the fitting member is such that the centers of the fitting member and the shaft member are aligned, and the inner peripheral surface and the side surface generates a moment that is changed so as to follow the inner peripheral surface, and makes the inner peripheral surface follow the side surface;
manufacturing an article by assembling the fitting member to the shaft member;
A method for manufacturing an article characterized by: A control method executed by a control unit that controls a robot body that brings a fitting member having an inner peripheral surface into contact with a shaft member having a side surface that contacts the inner peripheral surface, comprising :
The control unit
By the robot body,
bringing the fitting member into contact with the shaft member in an inclined state;
In a state in which the fitting member is in contact with the shaft member, the fitting member is moved in a first direction in which the fitting member is assembled to the shaft member, and in a direction orthogonal to the first direction. By controlling the movement in the second direction, the posture of the fitting member is such that the centers of the fitting member and the shaft member are aligned, and the inner peripheral surface and the side surface generates a moment that is changed so that the inner peripheral surface follows the side surface ,
A control method characterized by: A control program capable of executing the control method according to claim 22. A computer - readable recording medium storing the control program according to claim 23.

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