JP7134135B2 - ROBOT CONTROLLER, ASSEMBLY SUCCESS INSPECTION DEVICE, AND ASSEMBLY ASSEMBLY METHOD - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller, an assembly success/failure inspection device, and an assembly method that can determine whether or not an assembly has been successfully assembled.

Conventionally, in a robot that assembles parts, a force sensor is installed at the tip of the hand, and the force information detected by the force sensor during the assembly of parts and the position information of the tip of the robot are used to inspect whether the parts have been assembled successfully. A method for doing so has been proposed.

For example, in Patent Document 1, a partial waveform in an inspection range is extracted from a waveform showing the relationship between force information detected by a force sensor during assembly and positional information of the tip of the robot, and the difference between the maximum value and the minimum value in the partial waveform is A method for judging the success or failure of assembly based on whether or not a judgment criterion is satisfied is disclosed.

JP 2012-232384 A

The method of Patent Document 1 is used for assembly work in which a maximum value and a minimum value occur in a partial waveform that indicates the relationship between force information during assembly and positional information of the tip of the robot. Like the assembly work of , the force of the robot increases until the claws are engaged, the force decreases as soon as the claws are engaged, and the force increases when the robot pushes in. there is However, the method of Patent Literature 1 does not allow the occurrence of maximum and minimum values in the partial waveform that indicates the relationship between the force information during assembly and the positional information of the tip of the robot. Not suitable for assembly work. Therefore, it is desired to determine the success or failure of assembly work by a robot, regardless of the assembly structure of assembly parts and parts to be assembled.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a robot controller capable of judging the success or failure of an assembly operation by a robot regardless of the assembly structure of parts to be assembled and parts to be assembled. do.

In order to solve the above-described problems and achieve the object, a robot controller according to the present invention controls a robot that assembles an assembly by assembling a component gripped by a component gripper to a component to be assembled. The robot controller includes a motion control unit for controlling the motion of the robot, and a component gripping unit when the tip of the component gripping unit is pressed against a reference surface and the reaction force from the reference surface reaches a predetermined first value. and the position coordinates of the component gripper when the tip is pressed against the assembly and the reaction force from the assembly reaches a predetermined second value. and an assembly position acquisition unit that acquires the assembly position. The robot controller also includes an assembly dimension calculation unit that calculates the height dimension of the assembly from the difference between the reference position and the assembly position, and whether or not the height dimension of the assembly is within a predetermined threshold range. an assembly success/failure determination unit that determines whether the assembly has been successful or failed based on whether the assembly is successful or not. The reference plane is an arrangement plane on which the assembly target component is arranged in the component positioning unit on which the assembly target component is positioned and fixed. calculated by the height dimension of

Advantageous Effects of Invention According to the robot controller of the present invention, it is possible to determine the success or failure of assembly work by a robot regardless of the assembly structure of assembly parts and parts to be assembled.

1 is an overall view of a robot system including a robot controller according to Embodiment 1 of the present invention; FIG. Block diagram of the control system in the robot system shown in FIG. 1 is a diagram showing an example of a hardware configuration of a processing circuit according to the first embodiment of the present invention; FIG. Schematic diagrams showing motions of a gripping hand in assembling and inspecting an assembly performed by the robot system shown in FIG. 4 is a flow chart showing an operation procedure of a reference position acquisition operation according to Embodiment 1 of the present invention; FIG. 4 is a characteristic diagram showing an example of the relationship between the force detection value detected by the force sensor during the reference position acquisition operation and the position detection value in the first embodiment of the present invention; 1 is a flow chart showing an operation procedure of component assembly operation in Embodiment 1 of the present invention; Flowchart showing operation procedure of assembly position acquisition operation and assembly success/failure inspection method according to Embodiment 1 of the present invention FIG. 4 is a characteristic diagram showing an example of the relationship between the force detection value detected by the force sensor during the assembly position acquisition operation and the position detection value according to the first embodiment of the present invention; FIG. 2 is a schematic diagram showing an assembly assembly process and an assembly success/failure inspection process when assembly of the assembly fails in the robot system shown in FIG. 1; FIG. 2 is a characteristic diagram showing an example of the relationship between a force detection value detected by a force sensor and a position detection value during an assembly position acquisition operation when assembly of the assembly fails in the robot system shown in FIG. 1; FIG. 11 is a schematic diagram showing a reference position acquisition operation performed by the robot system shown in FIG. 1 in Embodiment 2 of the present invention; FIG. 5 is a flow chart showing an operation procedure of a reference position acquisition operation according to Embodiment 2 of the present invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION A robot controller, an assembly success/failure inspection device, and an assembly assembly method according to embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

Embodiment 1.
FIG. 1 is an overall view of a robot system 100 having a robot controller 7 according to Embodiment 1 of the present invention. FIG. 2 is a block diagram of a control system in the robot system 100 shown in FIG. The robot system 100 includes a robot 40 installed on an assembly table 60 and a robot controller 7 that controls the robot 40 .

The robot 40 has a base portion 41 arranged on an assembly table 60 and a robot arm 1 supported by the base portion 41 . The wrist of the robot arm 1 is equipped with a gripping hand 3 which is a part gripping unit provided with a force sensor 2 . A pair of gripping fingers 3 a for gripping the assembly component 4 is attached to the gripping hand 3 . The pair of gripping fingers 3 a are opened and closed by the gripping hand 3 to grip the assembly component 4 and release the gripped assembly component 4 . The assembly part 4 is an object to be gripped by the gripping hand 3 .

The gripping hand 3 grips the assembly component 4 by adjusting the distance between the pair of gripping fingers 3a. The robot arm 1 assembles the assembly component 4 to the assembly target component 5 positioned and fixed by the component positioning unit 6 installed on the assembly table 60 while the gripping hand 3 grips the assembly component 4 . .

The force sensor 2 detects a force acting on the tip 3b of the gripping hand 3. As shown in FIG. That is, the force sensor 2 detects forces acting on the tip portions 3b of the pair of gripping fingers 3a.

The robot controller 7 includes an arithmetic function unit and a storage unit, controls the robot arm 1 and the gripping hand 3 according to the robot program stored in the storage unit, and controls the assembly operation of the assembly component 4 to the assembly target component 5. and control of assembly success/failure inspection of the assembly. The robot controller 7 controls the robot arm 1 and the gripping hand 3 according to conditions for the assembly operation of the assembly part 4 and the branch determination set in advance in the robot program. In addition, the robot controller 7 controls the robot arm 1 and the gripping hand 3 according to the conditions of the assembly success/failure inspection operation and the branch judgment set in advance in the robot program.

In FIG. 1, the direction along the grasping direction is the X-axis direction, and the directions perpendicular to the X-axis are the Y-axis direction and the Z-axis direction. The Z-axis direction is a vertical direction along the direction in which the gripping hand 3 moves when the assembly component 4 gripped by the gripping hand 3 is assembled to the assembly target component 5 . As for the Z-axis direction, the vertically upward direction is the plus direction. Here, the gripping direction refers to the direction in which the pair of gripping fingers 3a approaches the assembly component 4 when the gripping hand 3 adjusts the distance between the pair of gripping fingers 3a to grip the assembly component 4 .

The robot controller 7 includes a motion control unit 71 that controls the motions of the robot arm 1 and the gripping hand 3 to control the motion of the robot 40 in assembling the assembly and the motion of the robot 40 in inspecting the success or failure of the assembly; an inspection control unit 72 for controlling assembly success/failure inspection processing; a storage unit 73 for storing various information relating to the operation of the robot 40 and assembly success/failure inspection; It comprehensively controls the motion of the robot 40 . Each component in the robot controller 7 can transmit and receive information to and from each other.

The robot program is a program for executing the control of the assembly operation of the assembly part 4 to the assembly target part 5, the control of the assembly success/failure inspection of the assembly, and the overall control of the robot controller 7. FIG. The robot program includes the control of the robot arm 1 and the gripping hand 3, such as the position of the robot arm 1, the position of the gripping hand 3, the procedure for assembling the assembly parts 4, the procedure for inspecting the success or failure of the assembly, and the like. In addition, information necessary for the assembly success/failure inspection of the assembly is stored.

The inspection control unit 72 includes a force acquisition unit 721, a position acquisition unit 722, a reference position acquisition unit 723, an assembly position acquisition unit 724, an assembly size calculation unit 725, and an assembly success/failure determination unit 726. .

The force acquisition unit 721 acquires the force acting on the distal end portion 3 b of the gripping hand 3 detected by the force sensor 2 .

The position acquisition unit 722 acquires the position coordinates of the robot arm 1 from the robot arm 1 when the force detection value detected by the force sensor 2 reaches a predetermined force detection value.

The reference position acquisition unit 723 determines the tip of the gripping hand 3 when the tip 3b of the gripping hand 3 is pressed against the reference surface and the reaction force from the reference surface reaches a first value, which is a predetermined force detection value. Get the reference position, which is the position coordinates of the position.

The assembly position acquisition unit 724 detects the gripping hand when the tip 3b of the gripping hand 3 is pressed against the upper surface of the assembly and the reaction force from the assembly reaches a second value, which is a predetermined force detection value. Acquire the assembly position, which is the position coordinates of the tip position of 3.

The assembly dimension calculator 725 calculates the height dimension of the assembly from the difference between the reference position and the assembly position.

The assembly success/failure determining unit 726 determines whether the assembly has been successfully assembled based on whether the height dimension of the assembly is within a predetermined threshold range.

The motion control unit 71 of the robot controller 7 described above is implemented, for example, as a processing circuit having the hardware configuration shown in FIG. FIG. 3 is a diagram of an example of a hardware configuration of a processing circuit according to the first embodiment of the present invention; When the operation control unit 71 is implemented by the processing circuit shown in FIG. 3, the operation control unit 71 is implemented by the processor 101 executing a program stored in the memory 102 shown in FIG. 3, for example. Also, multiple processors and multiple memories may work together to achieve the above functions. Also, part of the functions of the operation control unit 71 may be implemented as an electronic circuit, and other parts may be realized using the processor 101 and the memory 102 .

Further, the inspection control unit 72 of the robot controller 7 is implemented as a processing circuit having the hardware configuration shown in FIG. 3, for example. When the inspection control unit 72 is implemented by the processing circuit shown in FIG. 3, the inspection control unit 72 is implemented by the processor 101 executing a program stored in the memory 102 shown in FIG. 3, for example. Also, multiple processors and multiple memories may work together to achieve the above functions. Also, part of the functions of the inspection control unit 72 may be implemented as an electronic circuit, and other parts may be realized using the processor 101 and the memory 102 .

As the robot controller 7, a computer device having an arithmetic function and a memory or a control device such as a programmable logic controller (PLC) may be used.

The assembly success/failure inspection device according to the first embodiment is configured by a robot system 100 . That is, the robot system 100 has an assembling function of assembling an assembly by assembling an assembly part gripped by a part gripping part to a part to be assembled, and a function of inspecting whether or not the assembled assembly has been assembled successfully.

Next, a method for assembling an assembly including an assembly success/failure inspection method in the robot system 100 will be described. 4A and 4B are schematic diagrams showing the operation of the gripping hand 3 in assembly and inspection of the assembly performed by the robot system 100 shown in FIG. 4, FIGS. 4(a) and 4(b) show the reference position acquisition operation, FIGS. 4(c) and 4(d) show the parts assembly operation, and FIGS. 4(e) and 4( f) shows the assembly position acquisition operation. In the method of assembling an assembly in the robot system 100, a reference position acquisition operation, a component assembly operation, and an assembly position acquisition operation are performed. That is, in the method of assembling the assembly in the robot system 100, the assembly of the assembly 20 and the assembly success/failure inspection of the assembly 20 are performed.

The assembly 20 is assembled under the control of the motion control section 71 of the robot controller 7 . The inspection of the assembly 20 is performed under the control of the motion control section 71 and the inspection control section 72 of the robot controller 7 .

First, the reference position acquisition operation will be described. The reference position acquisition operation is performed prior to assembling the assembly 20 in the robot system 100 . FIG. 5 is a flow chart showing the operation procedure of the reference position acquisition operation according to Embodiment 1 of the present invention. FIG. 6 is a characteristic diagram showing an example of the relationship between the force detection value detected by the force sensor 2 during the reference position acquisition operation and the position detection value according to the first embodiment of the present invention. In FIG. 6, the vertical axis represents force detection values, and the horizontal axis represents position detection values during the reference position acquisition operation. The position detection value on the horizontal axis is the position detection value in the Z-axis direction, and the higher the position in the Z-axis direction, the larger the value.

In step S<b>110 , the robot arm 1 performs a pressing operation of pressing the tip 3 b of the gripping hand 3 against the reference surface 6 a of the component positioning unit 6 . As the robot arm 1 moves, the gripping hand 3 moves to a predetermined assembling work start point, as shown in FIG. 4(a). As the robot arm 1 moves, the gripping hand 3 moves downward in the Z-axis direction toward the reference surface 6a of the component positioning unit 6, and the tip 3b of the gripping hand 3 moves downward as shown in FIG. 4(b). contacts the reference surface 6a. The tip 3b of the gripping hand 3 is the tip of the pair of gripping fingers 3a.

After starting the reference position acquisition operation, the force sensor 2 acquires a force detection value detected by the force sensor 2 at a predetermined cycle, and transmits the force detection value to the force acquisition unit 721 . The force detected by the force sensor 2 here is the force acting on the tip 3b of the gripping hand 3 due to the pressing action of pressing the tip 3b of the gripping hand 3 against the reference surface 6a, and is the reaction force from the reference surface 6a. is. The weight of the grasping hand 3 is detected by the force sensor 2 until the tip 3b of the grasping hand 3 contacts the reference surface 6a. Therefore, the force detection value detected by the force sensor 2 becomes a negative value as shown in FIG.

Thereafter, when the tip 3b of the gripping hand 3 contacts the reference surface 6a, the pressing force of the robot arm 1 acts on the force sensor 2 in the direction opposite to the direction in which the weight of the gripping hand 3 is applied. When the tip 3b of the gripping hand 3 continues to be pressed against the reference surface 6a, the detected force value increases as shown in FIG. Point A in FIG. 6 indicates the state where the tip 3b of the gripping hand 3 contacts the reference plane 6a.

Next, in step S120, the force acquisition unit 721 monitors the force detection value sent from the force sensor 2, and reaches the force detection value Fa, which is a predetermined first value. Determine whether or not The force detection value Fa is determined in advance and stored in the force acquisition unit 721 . If the detected force value has not reached the detected force value Fa, the determination in step S120 is No, the process returns to step S110, and the robot arm 1 continues the pressing operation. When the force detection value reaches the force detection value Fa, the determination in step S120 is Yes, and the process proceeds to step S130.

Next, in step S130, the robot arm 1 stops the pressing operation of pressing the tip portion 3b of the gripping hand 3 against the reference surface 6a.

Next, in step S140, the reference position acquisition unit 723 acquires the position detection value Za when the robot arm 1 stops the pressing operation. The position detection value Za is the value of the gripping hand 3 when the force detection value detected by the force sensor 2 reaches the predetermined force detection value Fa in the reference position acquisition operation and the robot arm 1 stops the pressing operation. It is the position coordinates of the tip portion 3b. Specifically, the detected position value Za is the position coordinate of the tip 3b of the gripping hand 3 in the Z-axis direction. Further, the position detection value Za is a reference position in the Z-axis direction when calculating the assembly size Hp of the assembly 20 as described later.

The position acquisition unit 722 obtains information on the position coordinates of the robot arm 1 when the force detection value detected by the force sensor 2 reaches a predetermined force detection value Fa, that is, the robot arm corresponding to the force detection value Fa. 1 is obtained from the robot arm 1 and transmitted to the reference position obtaining unit 723 . Information on the positional coordinates of the robot arm 1 is obtained by a known technique, so the description thereof is omitted.

The reference position acquisition unit 723 acquires information indicating the correlation between the position coordinates of the robot arm 1 and the position coordinates of the tip 3b of the gripping hand 3, information on the position coordinates of the robot arm 1 corresponding to the detected force value Fa, , the position detection value Za is calculated and obtained.

Next, in step S150, the reference position acquisition unit 723 causes the storage unit 73 to store the acquired position detection value Za. By performing the above operation, the reference position acquisition operation is completed.

Next, the parts assembly operation will be described. The parts assembly operation is performed after the reference position acquisition operation is finished. FIG. 7 is a flow chart showing an operation procedure of component assembly operation in the first embodiment of the present invention.

In step S210, as shown in FIG. 4(c), the component to be assembled 5 is positioned and fixed on the reference surface 6a of the component positioning section 6. As shown in FIG. Positioning and fixing of the assembly target component 5 onto the component positioning unit 6 may be performed by the robot arm 1 or may be performed by another robot.

Next, in step S220, the robot arm 1 grips the assembly component 4 with the gripping hand 3 as shown in FIG. 4(c).

Next, in step S230, by moving the robot arm 1, the assembly part 4 is moved in a direction to press the assembly part 4 against the assembly part 5, and the assembly part 4 is pushed against the assembly part 5 as shown in FIG. 4(d). Then, the operation of assembling the assembly parts 4 is performed. By performing the above operations, the component assembly operation is completed.

Next, an assembly position acquisition operation and an assembly success/failure inspection method will be described. The assembly position acquisition operation is performed after the parts assembly operation is finished. FIG. 8 is a flow chart showing the operation procedure of the assembly position acquisition operation and assembly success/failure inspection method according to the first embodiment of the present invention. FIG. 9 is a characteristic diagram showing an example of the relationship between the force detection value detected by the force sensor 2 and the position detection value during the assembly position acquisition operation according to the first embodiment of the present invention. In FIG. 9, the vertical axis represents force detection values, and the horizontal axis represents position detection values during the assembly position acquisition operation. The position detection value on the horizontal axis is the position detection value in the Z-axis direction, and the higher the position in the Z-axis direction, the larger the value.

First, an assembly position acquisition operation is performed. In step S<b>310 , the robot arm 1 performs a pressing operation of pressing the tip 3 b of the gripping hand 3 against the assembly component 4 . That is, the grasping fingers 3a of the grasping hand 3 release the assembly component 4, and the robot arm 1 moves, thereby separating the grasping hand 3 upward from the assembly component 4 in the Z-axis direction. After that, by moving the robot arm 1, the gripping hand 3 moves the assembled parts 4 as shown in FIG. It moves downward in the Z-axis direction toward the solid 20 . Then, as shown in FIG. 4( f ), the tip 3 b of the gripping hand 3 contacts the top surface 4 a of the assembly component 4 , which is the top surface of the assembly 20 .

After starting the assembly position acquisition operation, the force sensor 2 acquires a force detection value detected by the force sensor 2 at a predetermined cycle, and transmits the force detection value to the force acquisition unit 721 . The force detected by the force sensor 2 here is the force acting on the tip 3b of the gripping hand 3 due to the pressing action of pressing the tip 3b of the gripping hand 3 against the top surface 4a of the assembly component 4, which is the top surface of the assembly 20. is. The weight of the grasping hand 3 is detected by the force sensor 2 until the tip 3b of the grasping hand 3 contacts the assembly component 4 . Therefore, the force detection value detected by the force sensor 2 becomes a negative value as shown in FIG.

After that, when the tip 3b of the gripping hand 3 contacts the upper surface 4a of the assembly component 4, the pressing force of the robot arm 1 acts on the force sensor 2 in the direction opposite to the direction in which the weight of the gripping hand 3 is applied. When the tip 3b of the gripping hand 3 continues to be pressed against the upper surface 4a of the assembly component 4, the force detection value increases as shown in FIG. Point B in FIG. 9 shows the state where the tip 3b of the grasping hand 3 comes into contact with the upper surface 4a of the assembly component 4. FIG.

Next, in step S320, the force acquisition unit 721 monitors the force detection value sent from the force sensor 2, and reaches the force detection value Fb, which is a predetermined second value. Determine whether or not The force detection value Fb is determined in advance and stored in the force acquisition unit 721 . If the detected force value has not reached the detected force value Fb, the determination in step S320 is No, the process returns to step S310, and the robot arm 1 continues the pressing operation. If the detected force value reaches the detected force value Fb, the determination in step S320 is Yes, and the process proceeds to step S330.

At step S<b>330 , the robot arm 1 stops the pressing operation of pressing the tip 3 b of the gripping hand 3 against the upper surface 4 a of the assembly component 4 .

Next, in step S340, the assembly position acquisition unit 724 acquires the position detection value Zb when the robot arm 1 stops the pressing operation. The position detection value Zb is the gripping hand 3 when the force detection value detected by the force sensor 2 reaches a predetermined force detection value Fb in the assembly position acquisition operation and the robot arm 1 stops the pressing operation. is the position coordinates of the tip portion 3b of the . Specifically, the position detection value Zb is the position coordinates of the tip 3b of the gripping hand 3 in the Z-axis direction. Further, the position detection value Zb is the assembly position in the Z-axis direction when calculating the assembly dimension Hp of the assembly 20 as will be described later.

The position acquisition unit 722 obtains information on the position coordinates of the robot arm 1 when the force detection value detected by the force sensor 2 reaches a predetermined force detection value Fb, that is, the robot arm corresponding to the force detection value Fb. 1 position coordinate information is obtained from the robot arm 1 and transmitted to the assembly position obtaining unit 724 .

The assembly position acquisition unit 724 obtains information indicating the correlation between the position coordinates of the robot arm 1 and the position coordinates of the tip 3b of the gripping hand 3, and information on the position coordinates of the robot arm 1 corresponding to the force detection value Fb. , the position detection value Zb is calculated and obtained.

Next, in step S350, the assembly position acquisition unit 724 causes the storage unit 73 to store the acquired position detection value Zb. By performing the above operations, the assembly position acquisition operation is completed.

Following the assembly position acquisition operation, the assembly success/failure determination is performed. In step S360, the assembly size calculator 725 calculates the assembly size Hp by the following equation (1). The assembly size calculator 725 stores the calculated assembly size Hp in the storage unit 73 . The assembly dimension Hp is the dimension of the assembly 20 after assembly in the Z-axis direction, that is, the height dimension of the assembly 20 after assembly.

Hp=Zb-Za (1)

Next, in step S370, the assembly success/failure determining unit 726 determines whether or not the calculated assembly dimension Hp is within a predetermined assembly dimension threshold range. That is, the assembly success/failure determining unit 726 determines whether the calculated assembly size Hp is larger than the lower threshold of the predetermined threshold range of the assembly size and smaller than the upper threshold of the predetermined threshold range of the assembly size. determine whether or not If it is determined that the assembly dimension Hp is within the predetermined assembly dimension threshold range, the determination in step S370 is Yes, and the process proceeds to step S380. If it is determined that the assembly dimension Hp is not within the predetermined assembly dimension threshold range, the determination in step S370 is No, and the process proceeds to step S400.

In step S380, the assembly success/failure determining unit 726 determines that the assembled state of the assembly 20 is good and that the assembly of the assembly 20 has been successful, and proceeds to step S390.

Next, in step S390, the assembly success/failure determination unit 726 outputs the inspection result to the display unit 74 to display it on the display unit 74, and the series of the assembly operation of the assembly 20 and the inspection operation of the assembly 20 are completed.

In step S400, the assembly success/failure determining unit 726 determines that the assembled state of the assembly 20 is defective and that the assembly of the assembly 20 has failed, and proceeds to step S390.

The above-described reference position acquisition operation may be performed for each assembly of the assembly 20. However, by using the detected position value Za, which is the reference position stored in advance in the storage unit 73, the position of the assembly 20 after assembly can be determined. It is possible to obtain the assembly dimension Hp only by acquiring the detected value Zb. Therefore, the operation of acquiring the position detection value Za each time the assembly 20 is assembled is not required, and the cycle time for assembling the assembly 20 can be shortened.

However, if the gripping hand 3 and the reference surface 6a of the robot 40 are worn, or if the pressing force of the tip 3b of the gripping hand 3 changes due to changes in the detection performance of the force sensor 2 over time, etc., The force detection value detected by the force sensor 2 also changes during the reference position acquisition operation, making it impossible to correctly determine whether the assembly is successful. For this reason, the position detection value Za, which is the reference position, is obtained by performing the reference position acquisition operation at regular intervals, such as during the daily inspection performed once a day or the monthly inspection performed once a month, and stored in the storage unit. The reference position stored in 73 needs to be updated.

The force detection value Fa and the force detection value Fb are not such a large force as to damage the assembly part 4 and the part to be assembled 5 . Further, the detected force value Fa and the detected force value Fb are not so small that the force is erroneously detected when the robot arm 1 is not in contact with the assembly part 4 due to the influence of the acceleration during operation. The force detection value Fa and the force detection value Fb are applied to a part in which a gap is formed between the part to be assembled 4 and the part to be assembled 5 due to the dimensional tolerance of the part to be assembled 4 and the part to be assembled 5 . It is set to a moderate force that can be pressed until it disappears. Further, the detected force value Fa and the detected force value Fb may be the same value or different values as long as they are set so that the assembly dimension Hp can be calculated correctly.

The force detection values Fa and force detection values Fb are obtained by repeatedly measuring the assembly dimension Hp a plurality of times for a plurality of assemblies 20 that have been normally assembled. It is set so that the measurement results are stable. The result that the assembly dimension Hp is stabilized means that it can be confirmed that the dimension is within the dimension range considering the dimensional tolerance between the component to be assembled 4 and the component to be assembled 5 .

However, even if the assembly position acquisition operation is performed under the same condition of the force detection value Fb, the material and shape of the assembly part 4 and the assembly target part 5 may cause the tip 3b of the gripping hand 3 to be pressed. As the reaction force changes, the force detection value detected by the force sensor 2 changes. Therefore, it is necessary to consider the materials and shapes of the assembly part 4 and the assembled part 5 as well.

Next, a case where assembly of the assembly 20 fails will be described. FIG. 10 is a schematic diagram showing an assembly assembly process and an assembly success/failure inspection process when assembly of the assembly 20 in the robot system 100 shown in FIG. 1 fails, and corresponds to FIG. In FIG. 10, FIGS. 10(a) and 10(b) show reference position acquisition operations, FIGS. 10(c) and 10(d) show parts assembly operations, and FIGS. 10(f) shows the assembly position acquisition operation. FIG. 11 shows an example of the relationship between the force detection value detected by the force sensor 2 and the position detection value during the assembly position acquisition operation when assembly of the assembly 20 in the robot system 100 shown in FIG. 1 fails. It is a characteristic diagram showing. In FIG. 11, the vertical axis represents force detection values, and the horizontal axis represents position detection values during the assembly position acquisition operation. The position detection value on the horizontal axis is the position detection value in the Z-axis direction, and the higher the position in the Z-axis direction, the larger the value.

The reference position acquisition operation shown in FIG. 10 is the same as the procedure shown in FIGS. 4(a) and 4(b).

In the component assembly operation shown in FIG. 10, the position of the gripping hand 3 in the X-axis direction is deviated from the position of the component positioning unit 6 as shown in FIG. 10(c). As a result, the assembly part 4 rides on the to-be-assembled part 5 while the assembly position of the assembly part 4 is deviated in the X-axis direction, and the assembly of the assembly 20 fails as shown in FIG. 10(d).

10(e) and 10(f), the assembly position acquisition operation shown in FIG. 4(e) and 4(f), except that the grasping hand 3 continues to be pushed into the upper surface 4a of the assembly component 4. FIG.

The position detection value Zc detected in this case is, as shown in FIG. 11, a value larger than the position detection value Zb detected when the assembly 20 is successfully assembled. Therefore, in this case, the value of the assembly dimension Hp calculated by the above formula (1) is larger than the value calculated when the assembly 20 is successfully assembled, is greater than the upper threshold of the threshold range of assembly dimensions specified.

By setting the threshold range of the size of the assembly to a numerical value between the position detection value Zc and the position detection value Zb, it is possible to determine whether the assembly 20 has been successfully assembled.

As described above, in the method of assembling the assembly according to the first embodiment, the gripping hand 3 is pressed against the reference surface 6a of the component positioning section 6, and the gripping hand 3 contacts the reference surface 6a. Further, when the grasping hand 3 is pushed into the reference surface 6a and the force detection value reaches a predetermined force detection value Fa, the pressing of the grasping hand 3 is stopped. Then, the position detection value Za when the gripping hand 3 stops being pressed is acquired and stored in the storage unit 73 as the reference position.

Next, the part to be assembled 5 is positioned and fixed on the part positioning part 6 , and the part to be assembled 4 is gripped by the gripping hand 3 and assembled to the part to be assembled 5 .

Next, the grasping hand 3 is pressed against the upper surface 4a of the assembly component 4, which is the upper surface of the assembled assembly 20, and the grasping hand 3 contacts the reference surface 6a. Further, when the grasping hand 3 is pushed into the upper surface 4a of the assembly component 4 and the force detection value reaches a predetermined force detection value Fb, the pressing of the grasping hand 3 is stopped. Then, the position detection value Zb when the pressing of the gripping hand 3 is stopped is acquired and stored in the storage unit 73 as the assembly position.

Thereafter, an assembly dimension Hp, which is the height dimension of the assembly 20, is calculated from the difference between the reference position and the assembly position. If the assembly size Hp falls within the predetermined threshold range, it is determined that the assembly of the assembly 20 has been successfully assembled. assembly is determined to be unsuccessful.

In the method for assembling the assembly according to the first embodiment, it is possible to determine the success or failure of the assembly work by the robot 40 regardless of the assembly structure of the assembly part 4 and the part to be assembled 5 .

In addition, in the method of assembling the assembly according to the first embodiment, the assembly 20 can be inspected using the grasping hand 3, and the tip 3b of the grasping hand 3 acquired by the force sensor 2 is acted on. Since it is possible to inspect whether or not the assembly 20 has been successfully assembled using the force information and the position information of the tip 3b of the gripping hand 3, the distance A detection device such as a sensor or the like dedicated to the inspection of assembly success/failure of the assembly 20 becomes unnecessary, and the cost of the assembly success/failure inspection can be suppressed.

In addition, in the method of assembling the assembly according to the first embodiment, the assembly 20 can be inspected immediately after the assembly 20 is assembled without moving the assembly 20 to a dedicated inspection area. becomes. As a result, according to the method of assembling the assembly according to the first embodiment, the effects of simplification of equipment used for inspection of the assembly 20, cost reduction, and cycle time reduction can be obtained.

In the inspection method described in Patent Literature 1, the position of the tip of the robot is detected while the assembly is being gripped during the work of assembling the parts. Therefore, in the inspection method described in Patent Document 1, when the position of gripping the assembly is not accurate, that is, when the assembly is gripped or when the parts are assembled, the position of gripping the assembly is not correct. If it deviates from the correct position, the correct position cannot be detected.

On the other hand, in the method of assembling the assembly according to the first embodiment, the assembly component 4 is gripped in a process different from the process of assembling the assembly 20 by assembling the assembly component 4 to the assembly target component 5 . Since the assembly 20 is inspected for assembly success/failure without the above-described problems, it is possible to accurately evaluate the assembly success/failure of the assembly 20 .

Further, according to the robot controller 7 according to the first embodiment, it is possible to control the method of assembling the assembly according to the first embodiment, and to determine the success or failure of the assembly work by the robot 40 in the assembly process. A robot controller is obtained.

Embodiment 2.
In the second embodiment, a case where the block jig 8 is used to acquire the reference position will be described. FIG. 12 is a schematic diagram showing a reference position acquisition operation performed by the robot system 100 shown in FIG. 1 according to the second embodiment of the present invention. FIG. 13 is a flow chart showing the operation procedure of the reference position acquisition operation according to the second embodiment of the present invention.

In step S410, as shown in FIG. 12(a), the block jig 8 is positioned and fixed on the reference surface 6a of the component positioning unit 6 by the robot 40. As shown in FIG. The block jig 8 has a known height and is made of a rigid material that does not deform when gripped by the gripping hand 3 . The block jig 8 is composed of, for example, a solid metal material.

Next, in step S420, the dimension Hj of the block jig is input to the robot controller 7 and stored in the storage unit 73. FIG. The dimension Hj of the block jig is the height dimension of the block jig 8 in the Z-axis direction.

Next, in step S430, the robot arm 1 performs a pressing operation of pressing the tip portion 3b of the gripping hand 3 against the upper surface 8a of the block jig 8. As shown in FIG. As the robot arm 1 moves, the gripping hand 3 moves to a predetermined assembly work start point, as shown in FIG. 12(a). As the robot arm 1 moves, the gripping hand 3 moves downward in the Z-axis direction toward the upper surface 8a of the block jig 8, and as shown in FIG. It comes into contact with the upper surface 8a of the block jig 8.

Next, in step S440, the force acquisition unit 721 monitors the force detection value sent from the force sensor 2, and reaches the force detection value Fa, which is a predetermined first value. Determine whether or not If the detected force value has not reached the detected force value Fa, the determination in step S440 is No, the process returns to step S430, and the robot arm 1 continues the pressing operation. When the force detection value reaches the force detection value Fa, the determination in step S440 is Yes, and the process proceeds to step S450.

Next, in step S450, the robot arm 1 stops the pressing operation of pressing the tip 3b of the gripping hand 3 against the upper surface 8a of the block jig 8. As shown in FIG.

Next, in step S460, the reference position acquisition unit 723 acquires the position detection value Zj when the robot arm 1 stops pressing. The position detection value Zj is the value of the grasping hand 3 when the force detection value detected by the force sensor 2 reaches a predetermined force detection value Fa in the reference position acquisition operation and the robot arm 1 stops the pressing operation. It is the position coordinates of the tip portion 3b. Specifically, the detected position value Zj is the position coordinate of the tip 3b of the gripping hand 3 in the Z-axis direction. Also, the position detection value Zj is used to calculate a reference position as described later.

Next, in step S470, the reference position acquisition unit 723 calculates the reference position using the following formula (2). The reference position calculated by the following formula (2) corresponds to the detected position value Za in the first embodiment described above.

Reference position = Zj-Hj (2)

Next, in step S480, the reference position acquisition unit 723 causes the storage unit 73 to store the calculated reference position.

Next, in step S490, the robot 40 removes the block jig 8 from the component positioning section 6. FIG.

After that, the robot 40 executes the parts assembly operation and the assembly position acquisition operation shown in FIGS. done.

In the second embodiment, when calculating the assembly dimension Hp, the detected position value Za, which is the reference position in the first embodiment, is replaced with the reference position calculated by the above equation (2). Therefore, the formula for calculating the assembly size Hp in the second embodiment is the following formula (3).

Hp=Zb-(Zj-Hj) (3)

That is, the reference position acquisition section 723 presses the tip portion 3b of the gripping hand 3 against the block jig 8 having a known height dimension, which is positioned and fixed on the reference surface 6a of the component positioning section 6, and the It functions as a block jig position acquisition section that acquires a position detection value Zj, which is the position coordinate of the tip position of the tip portion 3b of the gripping hand 3 when the reaction force reaches a predetermined first value. The position detection value Zj is the block jig position, which is the position of the block jig 8 positioned and fixed on the reference surface 6a of the component positioning section 6. FIG.

Also, the reference position acquisition unit 723 functions as a reference position calculation unit that calculates the reference position from the block jig position and the dimension Hj of the block jig.

As described above, in the second embodiment, when it is difficult to bring the gripping hand 3 into direct contact with the reference surface 6a of the component positioning unit 6, for example, the gripping hand 3 at the tip of the robot 40 and the component positioning unit 6 Even in the case of interference, etc., the reference position can be acquired indirectly through the block jig 8, and the assembly success/failure inspection can be performed correctly.

The configurations shown in the above embodiments show an example of the content of the present invention, and the techniques of the embodiments can be combined with each other, or can be combined with another known technique. However, part of the configuration may be omitted or changed without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 robot arm 2 force sensor 3 gripping hand 3b tip 4 assembly part 4a, 8a top surface 5 part to be assembled 6 part positioning unit 6a reference surface 7 robot controller 8 block jig 20 Assembly 40 Robot 41 Base Part 60 Mounting Table 71 Motion Control Part 72 Inspection Control Part 73 Storage Part 74 Display Part 100 Robot System 101 Processor 102 Memory 721 Force Acquisition Part 722 Position Acquisition unit 723 Reference position acquisition unit 724 Assembly position acquisition unit 725 Assembly dimension calculation unit 726 Assembly success/failure determination unit Fa, Fb Force detection value Hj Block jig dimension Hp Assembly dimension Za, Zb, Zc, Zj Position detection values.

Claims (3)

A robot controller that controls a robot that assembles an assembly by assembling an assembly part gripped by a part gripping part to a part to be assembled,
a motion control unit that controls the motion of the robot;
A reference position for obtaining a reference position, which is position coordinates of the component gripper when the tip of the component gripper is pressed against a reference surface and a reaction force from the reference surface reaches a predetermined first value. an acquisition unit;
Assembly position acquisition for acquiring an assembly position, which is position coordinates of the component gripper when the tip is pressed against the assembly and a reaction force from the assembly reaches a predetermined second value. Department and
an assembly dimension calculator that calculates a height dimension of the assembly from the difference between the reference position and the assembly position;
an assembly success/failure determination unit that determines whether or not the assembly has been successfully assembled based on whether or not the height dimension of the assembly is within a predetermined threshold range;
with
The reference surface is
an arrangement surface on which the part to be assembled is arranged in a part positioning portion on which the part to be assembled is positioned and fixed;
calculating from the positional coordinates of a jig whose height dimension is known and which is arranged on the arrangement surface, and the height dimension of the jig;
A robot controller characterized by: An assembly success/failure inspection device for inspecting the success or failure of assembling an assembly in which an assembly part gripped by a part gripping part of a robot is assembled to a part to be assembled,
the robot;
a force acquisition unit that acquires a force acting on the tip of the component gripping unit;
a position acquisition unit that acquires the position coordinates of the component gripping unit;
A reference position for obtaining a reference position, which is position coordinates of the component gripper when the tip of the component gripper is pressed against a reference surface and a reaction force from the reference surface reaches a predetermined first value. an acquisition unit;
Assembly position acquisition for acquiring an assembly position, which is position coordinates of the component gripper when the tip is pressed against the assembly and a reaction force from the assembly reaches a predetermined second value. Department and
an assembly dimension calculator that calculates a height dimension of the assembly from the difference between the reference position and the assembly position;
an assembly success/failure determination unit that determines whether or not the assembly has been successfully assembled based on whether or not the height dimension of the assembly is within a predetermined threshold range;
with
The reference surface is
an arrangement surface on which the part to be assembled is arranged in a part positioning portion on which the part to be assembled is positioned and fixed;
calculating from the positional coordinates of a jig whose height dimension is known and which is arranged on the arrangement surface, and the height dimension of the jig;
An assembly success/failure inspection device characterized by: An assembly assembly method for assembling the assembly by a robot system comprising the robot controller according to claim 1 and the robot, comprising:
The reference position acquisition unit is configured to determine the position of the component gripping unit when the tip of the component gripping unit is pressed against the reference surface and a reaction force from the reference surface reaches the predetermined first value. a reference position acquisition step of acquiring the reference position, which is coordinates;
an assembling step in which the robot assembles the assembled part by assembling the assembled part to the to-be-assembled part;
The assembly position acquisition unit is the position coordinates of the component gripping unit when the tip is pressed against the assembly and the reaction force from the assembly reaches the predetermined second value. an assembly position obtaining step of obtaining the assembly position;
an assembly dimension calculation step in which the assembly dimension calculation unit calculates the height dimension of the assembly using the difference between the reference position and the assembly position;
an assembly success/failure determination step in which the assembly success/failure determining unit determines whether or not the assembly has been successfully assembled based on whether or not the height dimension of the assembly is within the predetermined threshold range;
including
The reference surface is
an arrangement surface on which the part to be assembled is arranged in a part positioning portion on which the part to be assembled is positioned and fixed;
calculating from the positional coordinates of a jig whose height dimension is known and which is arranged on the arrangement surface, and the height dimension of the jig;
A method of assembling an assembly characterized by:

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