JP2012020345A - Fastening device and fastening method - Google Patents

Abstract

A fastening device capable of efficiently searching a position of a fastening hole over a wide range to correct a positional deviation and preventing incomplete fastening such as oblique biting.
An automatic screw tightening apparatus 100 includes an XYZ-axis direction driving robot 14 that moves a screw 20 to a target coordinate, a robot control computer 17 that calculates the target coordinate and transmits the target coordinate to the XYZ-axis direction driving robot 14, a screw 20, and a force sensor 16 that measures a reaction force value acting in the XY plane direction received by the robot 20 and transmits the reaction force value to the robot control computer 17. The robot control computer 17 includes a spiral calculation unit and a force control calculation. The spiral calculation unit calculates coordinates on the XY plane among the target coordinates so that the moving locus of the fastening part becomes a spiral track, and the force control calculation unit includes the reaction force Among the target coordinates, coordinates on the XY plane are calculated so that the value becomes small.
[Selection] Figure 1

Description

  The present invention relates to a fastening device and a fastening method. For example, the present invention relates to a fastening device and a fastening method for fastening two parts by inserting a fastening part such as a screw into a fastening hole on a workpiece and performing fastening.

  In recent years, various assembly processes in the manufacturing process, including the manufacture of home appliances and automobiles, tend to be increasingly complicated and precise. At present, since most of the assembly process relies on manual work, the realization of an automatic assembly process is strongly demanded by the industry.

  Conventionally, industrial robots have been used as automation means in the automatic assembly process. In the automatic assembly process, a method of regulating the position of a part by a positioning mechanism or a jig or measuring a work position by a camera and an image recognition unit is mainly used for positioning the parts to be assembled. However, with these methods, the position of the part is regulated by the outer shape of the fastening part, or the position is measured at a specific part of the fastening part, so that the position error at the part insertion part due to the dimensional tolerance inside the part is grasped. Cannot be performed, and the alignment accuracy may be insufficient.

  In order to improve the accuracy of alignment, a method is used in which measurement is performed at several points on the part, and the position of the part is corrected based on the measurement results. However, as the number of measurements increases, There is a problem that the working time is prolonged and the working efficiency is deteriorated.

  As a typical process of the automatic assembly process, for example, there is a “screw tightening” process in which a fastening component such as a screw is inserted into a fastening hole on the workpiece and tightened. An automatic screw tightening device that combines an automatic screw tightening driver and a direct-acting robot has been commercialized and used conventionally. However, when such a screw tightening device is used, if the position of the fastening hole is deviated from the design position due to workpiece variation or the like, it is not possible to properly correct the position and tighten the screw. For example, when a positional deviation of about 1/10 or more of the screw diameter occurs, incomplete screw tightening such as oblique biting, or an error stop and manual correction work is required.

  Patent Documents 1 to 3 disclose a technique for automatically correcting the position of a fastening component when a displacement occurs in the fastening hole position.

JP 2002-331428 A (published on November 19, 2002) JP 62-102928 A (published May 13, 1987) JP 7-160336 A (released on June 23, 1995)

  Patent Document 1 describes a method of tightening screws by a force control robot. Positioning operation by force control of the robot body performed by the robot controller based on the transmission result of the force sensor, a nut runner equipped with a socket holding the male screw on the transmission shaft is provided in the robot body via the force sensor; By tightening the male screw and the female screw attached to the workpiece by the rotation control of the nut runner performed by the nut runner control unit based on the command from the robot control unit, the screw does not become obliquely caught and is surely Can be screwed on.

  In the above method, position correction is performed by sensing a reaction force received by a screw with a force sensor. In this method, when the screw tip is about to enter the fastening hole, the direction of the reaction force can be detected by the force sensor to correct the position. However, in this method, position correction cannot be performed in the situation shown in FIG. FIG. 9 is a schematic diagram showing a situation in which position correction is impossible by a conventional force control technique. As shown in FIG. 9A, when the screw tip 93 of the screw 92 is not inside the fastening hole 91 and the flat surface of the screw tip 93 is in contact with the flat surface around the fastening hole 91 of the workpiece 90, the insertion direction The direction of displacement cannot be detected by the reaction force received by the screw 92 in the plane direction perpendicular to the direction, and the position cannot be corrected. Further, as shown in FIG. 9B, when the screw tip 93 rides on the burr 95 around the fastening hole 91, a large frictional resistance is generated when the screw 92 is moved, and the screw 92 is attached to the fastening hole. It is impossible to correct the position to 91. As described above, in Patent Document 1, there is a problem that the position cannot be corrected unless the screw tip 93 is in the fastening hole 91 at the initial stage.

  As a method for searching for an unknown target position, a method for searching according to a spiral trajectory is disclosed. Patent Document 2 describes a technique for checking a fastening torque in tightening a large-sized bolt, and moving a bolt holding portion according to a spiral locus every time the fastening torque exceeds a threshold value to prevent incomplete fastening such as oblique engagement. is doing. In Patent Document 3, when the locate pin is positioned at a predetermined position and the locate hole cannot be detected, the locate hole shape determination unit reads information on the shape of the locate hole from the compound data storage unit and drives the locate pin. A technique is described in which a locating pin can be inserted even when a slight misalignment occurs by scrolling a locating pin by a portion and searching for a locating hole.

  However, both of the techniques described in Patent Document 2 and Patent Document 3 are intended to perform position correction when a slight positional shift occurs. When a positional shift occurs over a wide range, The position cannot be corrected and output as an error.

  In view of such circumstances, the present invention is a fastening device for inserting and fastening a fastening part into a fastening hole, which can efficiently search a position of the fastening hole in a wide range and correct a positional deviation, and is obliquely engaged. An object of the present invention is to provide a fastening device that can prevent incomplete fastening such as intrusion.

  In order to solve the above-mentioned problems, a fastening device according to the present invention is a fastening device for inserting and fastening a fastening part into a fastening hole, and driving means for moving the fastening part to a target coordinate; Control means for calculating coordinates and transmitting to the driving means; and measuring means for measuring a reaction force value received in the fastening part and acting in a surface direction perpendicular to the insertion direction and transmitting to the control means, The control means includes a spiral calculation means and a force control calculation means, and the spiral calculation means is on a plane perpendicular to the insertion direction of the target coordinates so that the movement locus of the fastening part is a spiral locus. Coordinates are calculated, and the force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the reaction force value becomes small. .

  According to the above configuration, even when a large misalignment occurs between the fastening component and the fastening hole, the position of the fastening hole can be efficiently searched in a wide range by the spiral calculation means, and the misalignment can be corrected. Is possible. Further, by performing position correction so that the reaction force value acting in the surface direction perpendicular to the insertion direction is reduced by the force control calculation means, incomplete fastening such as oblique biting can be prevented.

  Further, in the fastening device according to the present invention, the control means includes calculation control means, and the calculation control means compares the reaction force value with a preset fastening hole contact threshold value, and the reaction force value is If the fastening hole contact threshold is smaller than the fastening hole contact threshold, the spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and if the reaction force value is larger than the fastening hole contact threshold, the force control. It is preferable that the computing means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates.

  According to the above configuration, the arithmetic control means compares the reaction force value measured by the measuring means with a preset fastening hole contact threshold value to determine whether the tip of the fastening part is inside the fastening hole. Can be determined. If the reaction force value is smaller than the fastening hole contact threshold, it is determined that the tip of the fastening part has not yet entered the fastening hole. If the reaction force value is larger than the fastening hole contact threshold, the tip of the fastening part is It is determined that it is inside. If the tip of the fastening part is not inside the fastening hole, the next target coordinate is calculated by the spiral calculation means, the fastening part is moved to the target coordinate, and the tip of the fastening part is inside the fastening hole. In this case, the next target coordinate can be calculated by the force control calculation means, and the fastening part can be moved to the target coordinate.

  Further, in the fastening device according to the present invention, the measuring means works in the X-axis direction and the Y-axis direction, which are directions parallel to each of two straight lines orthogonal to each other on a plane perpendicular to the insertion direction. It is preferable to measure an axial reaction force value and a Y-axis reaction force value, and the driving means preferably moves the fastening component in the X-axis direction and the Y-axis direction.

  According to the above configuration, the measuring means can measure the X-axis direction reaction force value and the Y-axis direction reaction force value independently, and the driving means can independently measure the X-axis direction and Y-axis direction. Fastening parts can be moved, and it becomes possible to calculate target coordinates and control positions more precisely.

  Further, in the fastening device according to the present invention, the measuring means calculates an in-plane reaction force value from the X-axis direction reaction force value and the Y-axis direction reaction force value according to the following formula (1), and the control means: Preferably, the force control calculation means calculates the coordinate in the X-axis direction and the coordinate in the Y-axis direction among the target coordinates so that the in-plane reaction force value becomes small.

In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
According to the above configuration, the force control calculation unit calculates the X-axis direction coordinate and the Y-axis direction coordinate among the target coordinates so that the in-plane reaction force value calculated by the measurement unit is as small as possible. As a result, it is possible to more efficiently search for the target coordinates of the point where the forces are balanced in a plane perpendicular to the insertion direction.

  Further, in the fastening device according to the present invention, the measuring means further measures a Z-axis direction reaction force value acting in a direction parallel to the insertion direction, and the driving means is the Z-axis direction. It is preferable to move the fastening part.

  According to the above configuration, the driving means can move the fastening part in the Z-axis direction according to the magnitude of the Z-axis direction reaction force value measured by the measuring means, and the Z-axis direction between the fastening part and the workpiece. It is possible to adjust the distance above.

  Further, in the fastening device according to the present invention, the control unit includes a Z-axis direction coordinate calculation unit, and the Z-axis direction coordinate calculation unit has a preset Z-axis direction in which the Z-axis direction reaction force value is set. It is preferable to calculate the coordinate in the Z-axis direction among the target coordinates so as to be the same as the reaction force reference value.

  According to the above configuration, the Z-axis direction coordinate calculation means calculates the Z-axis direction coordinates so that the Z-axis direction reaction force value is the same as the preset Z-axis direction reaction force reference value, and the drive means By moving the fastening part to the above-mentioned coordinates, it is possible to always keep the fastening part in contact with the work and to detect any step on the surface of the work.

  In the fastening device according to the present invention, the spiral track is preferably an Archimedean spiral.

  According to the above configuration, the Archimedean spiral can be searched efficiently because the distance between adjacent circles is equal, and the search can be completed in a shorter time.

  In the fastening device according to the present invention, it is preferable that a distance between adjacent circumferences of the spiral track is smaller than a difference between a diameter of the fastening part and a diameter of the fastening hole.

  According to the above configuration, the distance between the adjacent circumferences of the spiral track is smaller than the difference between the fastening part diameter and the fastening hole diameter, and the search range can be searched without omission and moves along the spiral track. The fastening parts always pass over the fastening holes.

Further, in the fastening device according to the present invention, the measuring means works in the X-axis direction and the Y-axis direction, which are directions parallel to each of two straight lines orthogonal to each other on a plane perpendicular to the insertion direction. The axial reaction force value and the Y-axis reaction force value are measured, and the in-plane reaction force value is calculated from the X-axis direction reaction force value and the Y-axis direction reaction force value according to the following formula (1). In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
The drive means moves the fastening part in the X-axis direction and the Y-axis direction, and the control means includes calculation control means and origin return calculation means, and the origin return calculation means includes Among the target coordinates, coordinates in the X-axis direction and the Y-axis direction are calculated so that the moving locus of the fastening part is a straight line toward the origin of the spiral-shaped trajectory. When the reaction force value is compared with a preset erroneous determination exclusion threshold value and the in-plane reaction force value is smaller than the erroneous determination exclusion threshold value, the origin return calculation means includes the X-axis direction and the Y-axis among the target coordinates. It is preferable to calculate the coordinates of the direction.

  According to the above configuration, if the fastening part once enters the fastening hole, but has come off again, or if the fastening part gets on the burr around the fastening hole, the fastening part has entered the fastening hole by mistake. When the determination is made, the erroneous determination can be detected by comparing the in-plane reaction force value with the erroneous determination exclusion threshold. If the in-plane reaction force value is smaller than the misjudgment exclusion threshold value, the origin return calculation means causes the moving locus of the fastening part to be a straight line toward the origin of the spiral trajectory. The coordinates in the Y-axis direction are calculated, and the fastening part is moved by the driving means. By providing the return-to-origin calculation means, even when the search cannot be continued, such as riding on a burr, it is possible to return to the origin of the spiral trajectory, so that an error stop does not occur.

  In the fastening device according to the present invention, the fastening component may be a screw, and the fastening device may include a fastening unit.

  According to the above configuration, the positional deviation can be corrected in a wide range, incomplete fastening such as oblique biting can be prevented, and the screw can be tightened efficiently and reliably.

In the fastening device according to the present invention, the measuring means works in the X-axis direction and the Y-axis direction, which are directions parallel to the two straight lines orthogonal to each other on a plane perpendicular to the insertion direction. Measure the reaction force value and the Y-axis direction reaction force value, calculate the in-plane reaction force value according to the following equation (1), and send it to the control means.
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
Furthermore, the Z-axis direction reaction force value acting in a direction parallel to the insertion direction is measured,
The drive means moves the fastening component in the X-axis direction, the Y-axis direction, and the Z-axis direction,
The control means further includes a calculation control means, a force control calculation means, and an origin return calculation means,
The arithmetic control means compares the Z-axis direction reaction force value with a preset Z-axis direction reaction force reference value, and if the Z-axis direction reaction force value is larger than the Z-axis direction reaction force reference value, The spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the spiral calculation means,
The calculation control means compares the in-plane reaction force value with a preset fastening hole contact threshold after the driving means moves the fastening part on the coordinates calculated by the spiral calculation means, If the in-plane reaction force value is larger than the fastening hole contact threshold value, the force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means calculates the force control Move the fastening part to the coordinates calculated by the computing means,
The calculation control means compares the in-plane reaction force value with a preset erroneous determination exclusion threshold after the driving means moves the fastening part on the coordinates calculated by the force control calculation means. If the in-plane reaction force value is smaller than the erroneous determination exclusion threshold, the origin return calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the drive means Move the fastening part to the coordinates calculated by the return calculation means,
The calculation control means compares the in-plane reaction force value with the fastening hole contact threshold after the driving means moves the fastening part on the coordinates calculated by the origin return calculation means, and If the internal reaction force value is larger than the fastening hole contact threshold, the force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the drive means is the force control calculation means Move the above fastening parts to the coordinates calculated by
The calculation control means is configured to move from the coordinates calculated by the force control calculation means to the origin of the spiral trajectory after the driving means moves the fastening part on the coordinates calculated by the force control calculation means. Comparing the distance with a preset origin approach threshold, and if the distance to the origin of the spiral trajectory is smaller than the origin approach threshold, the spiral calculation means is on a plane perpendicular to the insertion direction of the target coordinates. Preferably, the driving means is configured to move the fastening part to the coordinates calculated by the spiral calculation means.

  According to the above configuration, even when the fastening component is located either inside the fastening hole or outside the fastening hole at the initial stage, the fastening can be performed efficiently and reliably. Further, even if the search cannot be continued due to climbing on the burr or the like, it is possible to return to the vicinity of the spiral origin and perform the spiral search again by the origin return calculation means. During the movement to the origin, if the distance to the origin of the spiral trajectory is smaller than a preset origin approach threshold, a second spiral search is started.

In the fastening device according to the present invention, the measuring means works in the X-axis direction and the Y-axis direction, which are directions parallel to the two straight lines orthogonal to each other on a plane perpendicular to the insertion direction. Measure the reaction force value and the Y-axis direction reaction force value, calculate the in-plane reaction force value according to the following equation (1), and send it to the control means.
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
The fastening hole contact threshold is preferably a value larger than the maximum value of the in-plane reaction force value measured by moving a preset distance in a spiral shape under the condition that a fastening part does not enter the fastening hole in advance. .

  According to the above configuration, it is possible to accurately determine whether or not the fastening part is in the fastening hole by using an appropriate fastening hole contact threshold.

  In the fastening device according to the present invention, while calculating the target coordinates so that the in-plane reaction force value is reduced under the condition that the false determination exclusion threshold is previously a part of the fastening part in the fastening hole. It is preferable that the value is smaller than the average value of the in-plane reaction force values measured by moving the fastening part, and is an arbitrary value among values larger than zero.

  According to the above configuration, it is possible to accurately determine whether or not there is an erroneous determination by using an appropriate erroneous determination exclusion threshold.

  In the fastening device according to the present invention, it is preferable that the origin approach threshold is half of the distance between adjacent circumferences of the spiral track.

  According to the above configuration, by setting the origin of the first spiral search and the origin of the second spiral search to different positions, the second spiral search does not pass the same trajectory as before, but again at the same position. The possibility of causing erroneous determination can be reduced.

  In order to solve the above problems, a fastening method according to the present invention is a fastening method for inserting and fastening a fastening part into a fastening hole, and the movement locus of the fastening part is a spiral orbit, Calculates the coordinates on the plane perpendicular to the insertion direction among the target coordinates, and the spiral search process to move the fastening part to the target coordinate, and measures the reaction force value that the fastening part receives in the plane perpendicular to the insertion direction And calculating a coordinate on a plane perpendicular to the insertion direction among the target coordinates so that the reaction force value is small, and a force control search step of moving the fastening part to the target coordinates. If the reaction force value is smaller than the fastening hole contact threshold value, the spiral search process is executed, and if the reaction force value is larger than the fastening hole contact threshold value. , And executes the serial power control searching step.

  According to the above configuration, even when a large positional deviation occurs between the fastening component and the fastening hole, the position of the fastening hole can be efficiently searched in a wide range by the spiral search process, and the positional deviation is corrected. Is possible. In addition, by performing the position correction so that the reaction force value acting in the surface direction perpendicular to the insertion direction is reduced by the force control search step, incomplete fastening such as oblique biting can be prevented.

  The fastening device according to the present invention is an automatic fastening device for inserting and fastening a fastening part into a fastening hole, and driving means for moving the fastening part to a target coordinate, and calculating the target coordinate to the driving means. Control means for transmitting, and measuring means for measuring a reaction force value received in the fastening part and acting in a surface direction perpendicular to the insertion direction and transmitting the reaction force value to the control means, the control means comprising: a spiral computing means; Force control calculating means, wherein the spiral calculating means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the moving locus of the fastening part is a spiral orbit, The force control calculation means calculates the coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the reaction force value is small, and the position of the fastening hole is efficiently determined over a wide range. Ku can modify the search to the positional deviation, it is possible to prevent the incomplete conclusion of such biting diagonally, an effect that.

It is the schematic diagram which showed the structure of the automatic screw fastening apparatus which concerns on one Embodiment of this invention. It is the block diagram which showed the function structure of the automatic screw fastening apparatus which concerns on one Embodiment of this invention. It is the flowchart which showed the flow of the action | operation of the automatic screw fastening apparatus which concerns on one Embodiment of this invention. It is the figure which showed the example of the shape of the spiral in the spiral calculation which concerns on one Embodiment of this invention. It is the schematic diagram which showed the mode of the 1st spiral track | orbit and the 2nd spiral track | orbit which concern on one Embodiment of this invention. It is the figure which showed the movement locus | trajectory of a screw | thread when a screw front-end | tip is in a fastening hole at the time of grounding. It is the figure which showed the movement locus | trajectory of a screw | thread when a screw front-end | tip is in the exterior of a fastening hole at the time of grounding. It is the schematic diagram which showed the resin pin automatic insertion apparatus which concerns on one Embodiment of this invention. It is the schematic diagram shown about the situation where position correction by a prior art is impossible.

Embodiment 1
An embodiment of the present invention will be described below with reference to FIGS.

(1. Configuration of automatic screw tightening device)
First, the configuration of an automatic screw fastening device (fastening device) according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration of an automatic screw tightening device 100 according to an embodiment of the present invention. FIG. 1A shows the entire automatic screw tightening apparatus 100, and FIG. 1B is an enlarged view of a range 110 surrounded by a dotted line.

  An automatic screw tightening apparatus 100 according to the present invention includes an XYZ axial direction driving robot 14 (drive means), a screw tightening driver 15 (tightening means), a force sensor 16 (measurement means), a robot control computer 17 (control means), A work placement unit 18 and a bit 19 are provided.

  When performing automatic screw tightening, the bit 19 in the automatic screw tightening apparatus 100 holds a screw 20 (fastening component) at the tip of the bit, and two workpieces 21 and 22 are placed on the workpiece placement unit 18. The The automatic screw fastening device 100 is a device for inserting and fastening (fastening) the screw 20 into a fastening hole 23 penetrating the workpieces 21 and 22.

  In this specification, the X-axis direction and the Y-axis direction are directions parallel to two straight lines perpendicular to each other on a plane perpendicular to the screw insertion direction, and the Z-axis direction is the direction of the screw. The direction is parallel to the insertion direction. The XY plane direction is a plane direction perpendicular to the screw insertion direction.

The XYZ axis direction drive robot 14 includes an X axis direction drive arm 11 (X axis direction drive means), a Y axis direction drive arm 12 (Y axis direction drive means), and a Z axis direction drive arm 13 (Z axis direction drive means). I have. The X-axis direction drive arm 11, the Y-axis direction drive arm 12, and the Z-axis direction drive arm 13 can be controlled independently, and the screw 20 is moved in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. Can do. Upon receiving the target coordinates (X _n , Y _n , Z _n ) from the robot control computer 17, the XYZ axis direction drive robot 14 receives the X axis direction drive arm 11, the Y axis direction drive arm 12, and the Z axis direction drive arm 13. And the bit 19 is controlled to move the screw 20 held in the bit 19 to the target coordinates (X _n , Y _n , Z _n ).

The force sensor 16 is provided at the tip of the XYZ axial direction driving robot 14. The force sensor 16 has the magnitude of the reaction force that the screw 20 receives in the X-axis direction, the Y-axis direction, and the Z-axis direction, that is, the X-axis direction reaction force value F _x , the Y-axis direction reaction force value F _y , and the Z-axis. The direction reaction force value _Fz can be measured independently.

  The screw tightening driver 15 is connected to the tip of the XYZ axial direction driving robot 14 via a force sensor 16. The bit 19 is attached to the tip of the screw tightening driver 15. The bit 19 has a vacuum suction function and can hold the screw 20. The screw tightening driver 15 rotates the bit 19 when receiving a rotation start signal from the robot control computer 17, and stops the rotation of the bit 19 when receiving a rotation stop signal from the robot control computer 17 as the torque increases.

(2. Functional configuration of automatic screw tightening device)
Next, the configuration of the automatic screw fastening apparatus 100 will be described from a functional viewpoint with reference to FIG. FIG. 2 is a functional block diagram showing the main configuration of the automatic screw tightening apparatus 100 according to one embodiment of the present invention.

  The automatic screw tightening device 100 includes a force sensor 16, a robot control computer 17, an XYZ axial drive robot 14, and a screw tightening driver 15.

The force sensor 16 is a means for measuring a reaction force value received by a screw (fastening component). The force sensor 16 includes an X-axis direction reaction force value measurement unit 211, a Y-axis direction reaction force value measurement unit 212, a Z-axis direction reaction force value measurement unit 213, and a planar reaction force value calculation unit 214. The X-axis direction reaction force value measurement unit 211, the Y-axis direction reaction force value measurement unit 212, and the Z-axis direction reaction force value measurement unit 213 are the X-axis that the screw receives in the X-axis direction, the Y-axis direction, and the Z-axis direction. The direction reaction force value meter F _x , the Y-axis direction reaction force value F _y , and the Z-axis direction reaction force value F _z are measured. The plane reaction force value calculation unit 214 calculates an in-plane reaction force value F _xy according to the following equation (1).
In-plane reaction force value F _xy = (X-axis direction reaction force value F _x ² + Y-axis direction reaction force value F _y ² ) ^0.5 (1)
The force sensor 16 transmits the in-plane reaction force value F _xy and the Z-axis direction reaction force value F _z to the robot control computer 17.

The robot control computer 17 is a means for calculating target coordinates (X _n , Y _n , Z _n ) and transmitting them to the XYZ axial drive robot 14. The robot control computer 17 includes an arithmetic control unit 221 (calculation control unit), a spiral calculation unit (spiral calculation unit) 222, a force control calculation unit 223 (force control calculation unit), and an origin return calculation unit 224 (origin return calculation unit). , A Z-axis direction coordinate calculation unit 225 (Z-axis direction coordinate calculation means), and a storage unit 226 are provided. Details of each part will be described later.

The XYZ axial direction driving robot 14 is a means for moving the screw to the target coordinates. The XYZ axis direction drive robot 14 includes an X axis direction drive arm 11 (X axis direction drive means), a Y axis direction drive arm 12 (Y axis direction drive means), and a Z axis direction drive arm 13 (Z axis direction drive means). I have. The X-axis direction drive arm 11, the Y-axis direction drive arm 12, and the Z-axis direction drive arm 13 can move screws in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively. When the robot control computer 17 transmits the target coordinates (X _n , Y _n , Z _n ) to the XYZ axis direction driving robot 14, the X axis direction driving arm 11, the Y axis direction driving arm 12, and the Z axis direction driving arm 13 are object coordinates screws _{(X n, Y n, Z} n) is moved to.

  The screw tightening driver 15 is a means for tightening a screw. The screw tightening driver 15 rotates the screw when receiving a tightening start signal from the robot control computer 17, and stops the rotation when receiving a tightening stop signal. Further, when the screw tightening driver 15 detects a torque increase accompanying the rotation, the screw tightening driver 15 transmits a screw tightening completion signal to the robot control computer 17.

(3. Operation flow of automatic screw tightening device)
Here, the operation of the automatic screw fastening apparatus 100 will be described with reference to FIG. FIG. 3 is a flowchart showing the operation flow of the automatic screw tightening apparatus 100.

(3-1. Initialization process)
First, an initialization process (steps S0 to S2) for acquiring a screw and moving it to a predetermined fastening hole position will be described.

  The upper and lower two workpieces 21 and 22 having the fastening holes 23 are installed on the workpiece placing portion 18 and the automatic screw tightening operation is started (step S0).

The arithmetic control unit 221 of the robot control computer 17 acquires predetermined screw supply position coordinates (X ₁ , Y ₁ , Z ₁ ) from the storage unit 226 and transmits them to the XYZ axial direction driving robot 14. The XYZ axial drive robot 14 moves the bit to (X ₁ , Y ₁ , Z ₁ ). The bit acquires and holds the screw by vacuum suction (step S1).

The arithmetic control unit 221 of the robot control computer 17 obtains predetermined screw fastening hole coordinates (X ₂ , Y ₂ , Z ₂ ) from the storage unit 226 and transmits them to the XYZ axial direction driving robot 14. The XYZ axial direction driving robot 14 moves the screw to (X ₂ , Y ₂ , Z ₂ ) (step S2).

(3-2. Grounding confirmation process)
Next, a grounding confirmation process for confirming that the screw is grounded in the Z-axis direction will be described (steps S3 to S4).

The force sensor 16 measures the magnitude of the reaction force value received by the screw in the Z-axis direction by the Z-axis direction reaction force value measuring unit 213, and transmits the Z-axis direction reaction force value _Fz to the robot control computer 17. To do. The arithmetic control unit 221 of the robot control computer 17 acquires a preset ground contact determination threshold value F _contact from the storage unit 226, and compares the Z-axis direction reaction force value F _z with the ground contact determination threshold value F _contact . When the screw is in contact with the workpiece, the screw receives a reaction force from the workpiece (a reaction force in an axial direction parallel to the insertion direction). Accordingly, if the Z-axis direction reaction force value F _z > the contact determination threshold value F _contact, it can be determined that the screw is in contact with the workpiece (step S3).

If the Z-axis direction reaction force value F _z > the contact determination threshold value F _contact is determined as a result of the comparison, the arithmetic control unit 221 determines that the _contact is grounded and proceeds to step S5. On the other hand, if the Z-axis direction reaction force value F _z1 <the ground determination threshold value F _contact , the arithmetic control unit 221 determines that the ground is not in _contact , and calculates the next target coordinate to the Z-axis direction coordinate calculation unit 225. To instruct.

The Z-axis direction coordinate calculation unit 225 calculates the next target coordinates (X ₂ , Y ₂ , Z _{2 ′} ) for lowering the altitude of the screw while keeping the coordinates in the X and Y axes so that the screw approaches the workpiece. , Transmitted to the XYZ axial direction drive robot 14. The XYZ axis direction drive robot 14 moves the screw to the target coordinates (X ₂ , Y ₂ , Z _{2 ′} ) (step S4). Next, the ground contact determination (step S3) is performed again.

After step S4 in which the ground contact is confirmed, the calculation control unit 221 acquires a preset Z-axis direction reaction force reference value Z _standard from the storage unit 226, and the Z-axis direction reaction force value Fz and the Z-axis direction. The reaction force reference value Z _standard is compared. The Z-axis direction coordinate calculation unit 225 calculates the coordinates in the Z-axis direction among the target coordinates so that the Z-axis direction reaction force value Fz is always the same as the Z-axis direction reaction force reference value Z _standard . The Z-axis direction coordinate calculation unit 225 transmits the calculated coordinates in the Z-axis direction to the XYZ-axis direction driving robot 14. That is, if Z-axis direction reaction force value Fz> Z-axis direction reaction force reference value Z _standard , Z-axis direction reaction force value Fz <Z-axis direction reaction force reference value Z _standard is set in the direction in which the screw is moved away from the workpiece. For example, the coordinates in the Z-axis direction among the target coordinates are calculated in the direction in which the screw is brought closer to the workpiece. In the following description, description of the calculation of the Z-axis direction coordinate by the Z-axis direction coordinate calculation unit 225 and the movement of the screw in the Z-axis direction by the XYZ-axis direction driving robot 14 will be omitted.

(3-3. Spiral search process)
Next, the spiral search process (steps S5 to S7) for searching for the position of the fastening hole and causing the screw tip to enter the search hole will be described.

The arithmetic control unit 221 stores the coordinates (X ₂ , Y ₂ ) of the local point of the screw in the XY plane as the first spiral origin in the storage unit 226 (step S5).

Next, it is determined whether the tip of the screw is in the fastening hole at the first spiral origin (step S6). Force sensor 16 transmits the plane reaction force value F _x-y the screw is received in the robot control computer 17. The arithmetic control unit 221 acquires a preset fastening hole contact threshold value F _in-hole from the storage unit 226, and compares the _in- plane reaction force value F _xy with the fastening hole contact threshold value F _in-hole. .

When the screw tip is inside the fastening hole, the screw collides with the wall of the fastening hole and receives a reaction force in the plane direction perpendicular to the insertion direction. Therefore, the in-plane reaction force value F _xy is the contact with the fastening hole. If it is larger than the threshold value F _in-hole, it can be determined that the screw tip is inside the fastening hole. (Step S6)
As a result of the comparison, if the in-plane reaction force value F _xy > fastening hole contact threshold value F _in-hole , the arithmetic control unit 221 determines that the screw tip is inside the fastening hole, and proceeds to step S8. On the other hand, if the in-plane reaction force value F _xy <fastening hole contact threshold value F _in-hole, it is determined that the screw tip is outside the fastening hole, and the process proceeds to step S7.

In step S7, the spiral calculation unit 222 moves the screw at a constant speed in the XY plane direction, and the movement trajectory of Archimedes spreading outward is centered on the first spiral origin (X ₂ , Y ₂ ). The target coordinates (X _Spiral , Y _Spiral ) on the XY plane are calculated so as to form a spiral trajectory. The spiral calculation unit 222 transmits the calculated target coordinates (X _Spiral , Y _Spiral ) to the XYZ axial direction driving robot 14. The XYZ axis direction driving robot 14 moves the screw to the target coordinates (X _Spiral , Y _Spiral ).

  Next, Step S5 is performed again to determine whether the screw tip is inside the fastening hole.

  The spiral trajectory will be described with reference to FIG. FIG. 4 is a diagram showing an example of a spiral shape in the spiral calculation. In the present embodiment, as shown in FIG. 4A, an Archimedean spiral centering on the origin 40 is used, but other than this, for example, FIG. 4B and FIG. ) And a spiral centering on the origins 41 and 42, and the trajectory is not particularly limited as long as it has a spiral shape. Moreover, as shown to Fig.4 (a), it is preferable that the distance L1 between the circumferences which adjoin is smaller than the difference of a screw (fastening part) diameter and a fastening hole diameter. This makes it possible to search efficiently and without leakage, and the screw always passes over the fastening hole.

(3-4. Force control search process)
Even when the screw tip is inside the fastening hole, if there is a misalignment between the center position of the screw and the center position of the fastening hole, incomplete tightening such as oblique bite tends to occur. Next, a description will be given of a force control search step for making the screw and the fastening hole axes parallel and overlap.

  In step S8, the arithmetic control unit 221 sets the counter variable cnt to 0 and stores it in the storage unit 226.

In step S _<b> 9, the force control calculation unit 223 calculates target coordinates (X _fcontrol , Y _fcontrol ) in the XY plane direction so that the in-plane reaction force value F _xy approaches zero. Specifically, for example, the following equation (2) is proportional to the magnitudes of the X-axis direction reaction force value F _x and the Y-axis direction reaction force value F _{y at} the local point (X _{fcontrol 0} , Y _{fcontrol 0} ). Is used to calculate the displacement amount Δx in the X-axis direction and the displacement amount Δy in the Y-axis direction.

Δx = α × F _x Δy = β × F _y (2)
In the formula, α and β are constants.

Next, target coordinates (X _fcontrol , Y _fcontrol ) are calculated by the following equation (3).

X _fcontrol = X _{fcontrol 0} + _Δx
Y _fcontrol = Y _{fcontrol 0} + _Δy (3)
The force control calculation unit 223 transmits the calculated target coordinates (X _fcontrol , Y _fcontrol ) to the XYZ axis direction driving robot 14. The XYZ axial direction drive robot 14 moves the screw to the target coordinates (X _fcontrol , Y _fcontrol ).

  Subsequently, the arithmetic control unit 221 acquires the counter variable cnt from the storage unit 226, updates it as cnt = cnt + 1, and stores the updated counter variable value in the storage unit 226 again (step S10).

Next, it is determined again whether the screw tip is currently inside the fastening hole, that is, erroneous determination is eliminated (step S11). The arithmetic control unit 221 acquires a preset erroneous determination exclusion threshold value F _out-hole from the storage unit 226, and compares the in-plane reaction force value F _xy with the erroneous determination exclusion threshold value F _out-hole. .

When the screw tip is in the fastening hole, the screw collides with the wall of the fastening hole and receives in-plane reaction force (reaction force acting on the plane perpendicular to the insertion direction). The value F _xy will never be zero. If the in-plane reaction force value F _xy is smaller than the erroneous determination exclusion threshold F _out-hole, it can be determined that the screw tip does not enter the fastening hole (step S11).

For example, if the screw tip has once entered the inside of the fastening hole but has come off the fastening hole and is in contact with the flat part around the fastening hole, or the screw tip is not in the fastening hole but is If it is erroneously determined that it is inside the fastening hole in step S6 because it is in contact with the burr, the in-plane reaction force value F _xy is almost 0 at this time and is smaller than the erroneous determination exclusion threshold F _out-hole. Therefore, these can be detected.

As a result of the comparison, if the in-plane reaction force value F _xy > the erroneous determination exclusion threshold value F _out-hole , the arithmetic control unit 221 determines that the screw tip is inside the fastening hole, and proceeds to step S12. On the other hand, if the in-plane reaction force value F _xy <the erroneous determination exclusion threshold F _out-hole, it is determined that the screw tip is not inside the fastening hole, and the process proceeds to step S13.

Next, the arithmetic control unit 221 acquires the counter variable threshold value C _thr from the storage unit 226 and compares the counter variable cnt with the counter variable threshold value C _thr . If counter variable cnt> counter variable threshold value C _{thr as} a result of comparison, it is determined that the screw tip has been inside the fastening hole for a sufficiently long time and the position adjustment by force control has been sufficiently performed, and the process proceeds to step S16. . On the other hand, if counter variable cnt <counter variable threshold value C _thr, it is determined that the screw tip has not entered the fastening hole for a sufficiently long time, and the position adjustment by force control has not been performed sufficiently. The process proceeds to S9 (step S12).

(3-5. Origin return process)
If it is determined in step S11 that the in-plane reaction force value F _xy <the erroneous determination exclusion threshold value F _{out-hole as} a result of the comparison, it is determined that the screw tip is not inside the fastening hole, and the process proceeds to step S13. The reason why the in-plane reaction force value F _xy <the misjudgment exclusion threshold value F _out-hole is that although the screw tip once entered the fastening hole, it was immediately removed, or the burr around the fastening hole Possible reasons such as a collision. In this case, it is necessary to move to the first spiral origin and perform the spiral search process and the force control search process again.

In step S <b> 13, the calculation control unit 221 instructs the origin return calculation unit 224 to calculate target coordinates. The origin return calculation unit 224 makes X of the target coordinates so that the screw approaches the first spiral origin (X ₂ , Y ₂ ) recorded in step S5 from the current point at a constant speed and linearly. -Calculate the coordinates in the Y plane direction (X _return , Y _return ). The origin return calculation unit 224 transmits the calculated coordinates (X _return , Y _return ) to the XYZ axis direction driving robot 14. The XYZ axial direction drive robot 14 moves the screw to (X _return , Y _return ).

Next, it is determined whether or not the tip of the screw is in the fastening hole (step S14). The arithmetic control unit 221 acquires a preset fastening hole contact threshold value F _in-hole from the storage unit 226, and compares the _in- plane reaction force value F _xy with the fastening hole contact threshold value F _in-hole. .

When the screw tip is inside the fastening hole, the screw collides with the wall of the fastening hole and receives a reaction force in the plane direction perpendicular to the insertion direction. Therefore, the in-plane reaction force value F _xy is the contact with the fastening hole. If it is larger than the threshold value F _in-hole, it can be determined that the screw tip is in the fastening hole. (Step S14)
As a result of the comparison, if the in-plane reaction force value F _xy > fastening hole contact threshold value F _in-hole , the arithmetic control unit 221 determines that the screw tip is inside the fastening hole, and proceeds to step S8. On the other hand, if the in-plane reaction force value F _xy <fastening hole contact threshold value F _in-hole, it is determined that the screw tip is not inside the fastening hole, and the process proceeds to step S15.

Next, it is determined whether the current position is close to the first spiral origin (step S15). The arithmetic control unit 221 calculates a distance D between the current position and the first spiral origin (X ₂ , Y ₂ ). The arithmetic control unit 221 acquires a preset origin approach threshold value D _thr from the storage unit 226 and compares the distance D to the origin point with the origin approach threshold value D _thr . If the distance D> the origin approach threshold D _{thr as} a result of the comparison, the calculation control unit 221 determines that there is still a distance to the origin, and proceeds to step S13. On the other hand, if distance D <origin approach threshold D _thr , it is determined that the origin is approached, and the process proceeds to step S5.

(Tightening process)
If the comparison result is counter variable cnt> counter variable threshold C _thr in step S15, it is determined that the screw tip has been in the fastening hole for a sufficiently long time and that the position adjustment by force control has been sufficiently performed. Enter the tightening process. The tightening step is a step of performing tightening by rotating a screw while controlling force.

  The arithmetic control unit 221 transmits a rotation start command to the screw tightening driver 15 (step S16). The screw tightening driver 15 starts rotation of the screw.

The force control calculation unit 223 calculates target coordinates (X _fcontrol , Y _fcontrol ) so that the in-plane reaction force value F _xy approaches zero as much as possible, and transmits the target coordinates to the XYZ axial direction driving robot 14. The XYZ axial direction driving robot 14 moves the screw to the target coordinates (X _fcontrol , Y _fcontrol ) (step S17).

  The arithmetic control unit 221 detects whether there is a screw tightening completion signal. The screw tightening completion signal is a signal transmitted from the tightening means 240 to the arithmetic control unit 221 when a torque increase is detected with rotation. If the arithmetic control unit 221 cannot detect the screw tightening completion signal, the process proceeds to step S17. If the calculation control unit 221 can detect the screw tightening completion signal, the calculation control unit 221 transmits a rotation stop command to the tightening unit 240 and proceeds to step S19.

  In step S19, the arithmetic control unit 221 increases the altitude of the screw tightening driver 15, and retracts the screw tightening driver to an altitude so as not to collide with the workpiece even if the screw tightening driver moves.

  This completes the screw tightening operation by the automatic screw tightening device 100 (step S20).

(Various thresholds used)
Note that the various threshold values used in the present embodiment are preset numerical values, and for example, those determined by performing the following preliminary experiment can be used.

The screw 20 and the work 21 are brought into contact with each other in the Z-axis direction in a state where the tip of the screw 20 is not inside the fastening hole 23. While being in contact in the Z-axis direction, the spiral calculation unit 222 calculates coordinates on the XY plane among the target coordinates and transmits them to the XYZ-axis direction driving robot 14. The XYZ axial direction drive robot 14 moves the screw 20 to the coordinates calculated by the spiral calculation unit 222. Arithmetic control unit 221, XYZ axis driving robot 14 after moving the screw 20 on coordinates calculated by the spiral operation unit 222 records in a plane reaction force value F _x-y. A value larger than the recorded maximum value of the in-plane reaction force value F _xy can be set as the fastening hole contact threshold value F _in-hole . As a result, it is possible to determine whether or not the contact with the fastening hole is accurate.

Further, the screw 20 and the workpiece 21 are brought into contact with each other in the Z-axis direction in a state where the tip of the screw 20 is inside the fastening hole 23. While being in contact in the Z-axis direction, the spiral calculation unit 222 calculates coordinates on the XY plane among the target coordinates and transmits them to the XYZ-axis direction driving robot 14. The XYZ axial direction drive robot 14 moves the screw 20 to the coordinates calculated by the spiral calculation unit 222. The calculation control unit 221 moves the screw 20 on the coordinates calculated by the spiral calculation unit 222 by the XYZ axial direction drive robot 14 and then contacts the in-plane reaction force value F _xy with a preset fastening hole contact. The threshold value F _in-hole is compared. If the in-plane reaction force value F _xy is larger than the fastening hole contact threshold value F _in-hole , the force control calculation unit 223 calculates coordinates on the XY plane among the target coordinates and drives in the XYZ axial directions. Transmit to the robot 14. The XYZ axial direction drive robot 14 moves the screw 20 to the coordinates calculated by the force control calculation unit 223. Arithmetic control unit 221, XYZ axis driving robot 14 after moving the screw 20 on coordinates calculated by the force control calculating unit 223, and records in a plane reaction force value F _x-y. A value smaller than the average value of the recorded in-plane reaction force values F _xy can be set as the erroneous determination exclusion threshold F _out-hole . Thereby, it is possible to determine whether or not the determination is erroneous.

The origin approach threshold D _thr may be half of the distance between adjacent circumferences of the spiral trajectory. Next, the reason why the origin approach threshold is set in this way will be described with reference to FIG. FIG. 5 is a schematic diagram showing the state of the first spiral search trajectory and the second spiral search trajectory.

As shown in FIG. 5, in the first spiral search, the screw moves along the Archimedean spiral path 51 that spreads outward from the point 50. In the vicinity of the point 53, it is determined that the screw tip has entered the fastening hole, and the control is switched to the force control search. As a result of the position search by force control, it is determined that there is an erroneous determination in the vicinity of the point 54, and the point 54 to the point 55 are moved by the origin return search. Since the distance between the point 55 and the point 50 is smaller than half of the distance between adjacent circumferences of the spiral trajectory (the origin approach threshold D _thr ), the second spiral search is started. In the second spiral search, the screw moves along Archimedes' spiral spiral track 56 that spreads outward about the point 55. As a result, the point 50 serving as the origin of the first spiral orbit and the point 55 serving as the second spiral origin do not overlap, so the first spiral orbit 51 and the second spiral orbit 56 do not overlap. The trajectory does not pass through the point 53 where the erroneous determination encountered first time during the second spiral search. For this reason, the possibility of erroneous determination occurring in the second spiral search is reduced.

  Next, referring to FIG. 6 and FIG. 7, when performing screw tightening using the automatic screw tightening device 100 according to the present embodiment, when the screw is grounded to the workpiece, the screw tip is inside the tightening hole. Each of them will be described assuming the case of being outside the fastening hole.

FIG. 6 is a diagram showing the movement trajectory of the screw when the screw tip at the time of grounding is inside the fastening hole. As shown in FIG. 6A, when the tip of the screw 20 contacts the workpiece, the tip of the screw 20 is inside the fastening hole 23. FIG. 6B is a schematic view showing the fastening hole 23 as seen from above.
As shown in FIG. 6B, the screw tip is located at the point 60. By the spiral search, the screw 20 moves along the spiral path 61 centered on the point 60. At the point 62, the screw 20 collides with the fastening hole 23. The screw moves to point 63 by force control search. At point 63, the tightening device rotates the screw and tightens.

FIG. 7 is a diagram showing the movement trajectory of the screw when the tip of the screw at the time of grounding is inside the fastening hole. As shown in FIG. 7A, when the tip of the screw 20 contacts the workpiece, the tip of the screw 20 is outside the fastening hole 23. FIG. 7B is a schematic view showing a state in which the fastening hole 23 is viewed from the upper surface.
As shown in FIG. 7B, the screw tip is located at the point 70. By the spiral search, the screw 20 moves along the spiral track 71 centered on the point 70. At the point 72, the screw 20 collides with the fastening hole 23. The screw moves to point 73 by force control search. At point 73, the tightening device rotates the screw and tightens.

(4. Automatic screw tightening method)
The automatic screw tightening method according to the present invention is a method for inserting a screw (fastening component) into a fastening hole and fastening it. The above-described automatic screw tightening method calculates a coordinate on a plane perpendicular to the insertion direction so that the movement locus of the screw becomes a spiral orbit, and moves the screw to the target coordinate. A force control search step of measuring a reaction force value received in a vertical plane, calculating coordinates on a plane perpendicular to the insertion direction so that the reaction force value is small, and moving a screw to a target coordinate; The reaction force value is compared with a predetermined fastening hole contact threshold value. If the reaction force value is smaller than the fastening hole contact threshold value, a spiral search process is executed. If the reaction force value is larger than the fastening hole contact threshold value, a force control search is performed. Execute the process.

[Embodiment 2]
Next, another embodiment according to the present invention will be described with reference to FIG. FIG. 8 is a schematic diagram illustrating a resin pin automatic insertion device 800 according to the second embodiment. In addition, description is abbreviate | omitted about the part same as the automatic screw fastening apparatus which concerns on Embodiment 1, and only a different part is demonstrated.

  The resin pin automatic insertion device 800 uses a resin pin 81 (fastening component) instead of a screw, and includes a resin pin grip 80 instead of a screw tightening driver. By inserting the resin pin 81 into the insertion hole 84 (fastening hole) penetrating the workpiece 82 and the workpiece 83, the claw 85 of the resin pin 81 is caught around the insertion hole 84, and the workpiece 82 and the workpiece 83 are fixed ( Conclusion). Resin pin automatic insertion device 800 is the same as automatic screw tightening device 100 in terms of measurement means, control means, and drive means, except that it does not include tightening means.

  By using the resin pin automatic insertion device 800, the position can be corrected by performing a spiral search and a force control search even when the resin pin 81 is displaced from the insertion hole 84 and does not enter the insertion hole during grounding. . As a result, the resin pin can be inserted efficiently and reliably.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for various automatic assembly processes including manufacturing of home appliances and automobiles.

11 X-axis direction drive arm (X-axis direction drive means)
12 Y-axis direction drive arm (Y-axis direction drive means)
13 Z-axis direction drive arm (Z-axis direction drive means)
14 XYZ axial drive robot (drive means)
15 Screw tightening driver (Tightening device)
16 Force sensor (measuring means)
17 Robot control computer (control means)
18 Workpiece mounting part 19 Bit 20 Screw (fastening part)
21 Work 22 Work 23 Fastening hole 80 Resin pin gripping part 81 Resin pin (fastening part)
82 Workpiece 83 Workpiece 84 Insertion hole (fastening hole)
85 Claw 100 Automatic screw fastening device (automatic fastening device)
211 X-axis direction reaction force value measurement unit 212 Y-axis direction reaction force value measurement unit 213 Z-axis direction reaction force value measurement unit 214 Plane reaction force value calculation unit 221 Calculation control unit (calculation control means)
222 Spiral calculation unit (spiral calculation means)
223 Force control calculation unit (force control calculation means)
224 Origin return calculation unit (origin return calculation means)
225 Z-axis direction coordinate calculation unit (Z-axis direction coordinate calculation means)
226 Storage unit 800 Resin pin automatic insertion device (automatic fastening device)

Claims (15)

A fastening device for inserting and fastening a fastening part into a fastening hole,
Driving means for moving the fastening part to a target coordinate;
Control means for calculating the target coordinates and transmitting them to the driving means;
Measuring means for measuring the reaction force value acting in the surface direction perpendicular to the insertion direction received by the fastening part and transmitting it to the control means;
With
The control means includes a spiral calculation means and a force control calculation means,
The spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the moving locus of the fastening part is a spiral orbit,
The fastening device according to claim 1, wherein the force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the reaction force value becomes small. The control means includes calculation control means,
The arithmetic control means is
Compare the reaction force value with a preset fastening hole contact threshold, and if the reaction force value is smaller than the fastening hole contact threshold,
The spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates,
2. The fastening according to claim 1, wherein if the reaction force value is larger than the fastening hole contact threshold, the force control calculation means calculates coordinates on a plane perpendicular to an insertion direction among the target coordinates. apparatus. The measuring means works in the X-axis direction and the Y-axis direction and acts in the X-axis direction and the Y-axis direction, which are parallel to each of two orthogonal lines on a plane perpendicular to the insertion direction. Measuring force values,
The fastening device according to claim 1, wherein the driving unit moves the fastening part in the X-axis direction and the Y-axis direction. The measuring means calculates an in-plane reaction force value from the X-axis direction reaction force value and the Y-axis direction reaction force value according to the following formula (1), and transmits the calculated value to the control means.
The force control calculation means is configured to reduce the in-plane reaction force value.
The fastening device according to claim 3, wherein coordinates in the X-axis direction and coordinates in the Y-axis direction are calculated among the target coordinates.
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1) The measurement means further measures a Z-axis direction reaction force value acting in a direction parallel to the insertion direction,
The fastening device according to any one of claims 1 to 4, wherein the driving means moves the fastening part in the Z-axis direction. The control means includes Z-axis direction coordinate calculation means,
The Z-axis direction coordinate calculation means calculates the Z-axis direction coordinate of the target coordinates so that the Z-axis direction reaction force value is the same as a preset Z-axis direction reaction force reference value. The fastening device according to claim 5.   The fastening device according to claim 1, wherein the spiral track is an Archimedean spiral. The distance between adjacent circumferences of the spiral trajectory is
The fastening device according to claim 1, wherein the fastening device is smaller than a difference between a diameter of the fastening part and a diameter of the fastening hole. The measuring means works in the X-axis direction and the Y-axis direction and acts in the X-axis direction and the Y-axis direction, which are parallel to each of two orthogonal lines on a plane perpendicular to the insertion direction. A force value is measured, an in-plane reaction force value is calculated from the X-axis direction reaction force value and the Y-axis direction reaction force value according to the following formula (1), and is transmitted to the control means.
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
The driving means moves the fastening part in the X-axis direction and the Y-axis direction,
The control means includes calculation control means and origin return calculation means,
The origin return calculation means calculates coordinates in the X-axis direction and the Y-axis direction among the target coordinates so that the movement locus of the fastening part is a straight line toward the origin of the spiral track,
The arithmetic control means compares the in-plane reaction force value with a preset erroneous determination exclusion threshold, and if the in-plane reaction force value is smaller than the erroneous determination exclusion threshold,
The fastening device according to any one of claims 1 to 8, wherein the origin return calculation means calculates coordinates in the X-axis direction and the Y-axis direction among the target coordinates. The fastening part is a screw,
The fastening device according to any one of claims 1 to 9, wherein the fastening device comprises fastening means. The measuring means works in the X-axis direction and the Y-axis direction and acts in the X-axis direction and the Y-axis direction, which are parallel to each of two orthogonal lines on a plane perpendicular to the insertion direction. Measure the force value, calculate the in-plane reaction force value according to the following formula (1) and send it to the control means,
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
Furthermore, the Z-axis direction reaction force value acting in a direction parallel to the insertion direction is measured,
The drive means moves the fastening component in the X-axis direction, the Y-axis direction, and the Z-axis direction,
The control means further includes a calculation control means, a force control calculation means, and an origin return calculation means,
The arithmetic control means compares the Z-axis direction reaction force value with a preset Z-axis direction reaction force reference value,
If the Z-axis direction reaction force value is larger than the Z-axis direction reaction force reference value,
The spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the spiral calculation means,
The calculation control means compares the in-plane reaction force value with a preset fastening hole contact threshold after the driving means moves the fastening part on the coordinates calculated by the spiral calculation means,
If the in-plane reaction force value is greater than the fastening hole contact threshold,
The force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the force control calculation means,
The calculation control means compares the in-plane reaction force value with a preset erroneous determination exclusion threshold after the driving means moves the fastening part on the coordinates calculated by the force control calculation means. ,
If the in-plane reaction force value is smaller than the erroneous determination exclusion threshold,
The origin return calculating means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the origin return calculating means,
The calculation control means compares the in-plane reaction force value with the fastening hole contact threshold after the driving means moves the fastening part on the coordinates calculated by the origin return calculation means,
If the in-plane reaction force value is greater than the fastening hole contact threshold,
The force control calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the force control calculation means,
The calculation control means is configured to move from the coordinates calculated by the force control calculation means to the origin of the spiral trajectory after the driving means moves the fastening part on the coordinates calculated by the force control calculation means. Compare the distance and the preset origin approach threshold, and if the distance to the origin of the spiral trajectory is smaller than the origin approach threshold,
The spiral calculation means calculates coordinates on a plane perpendicular to the insertion direction among the target coordinates, and the driving means moves the fastening part to the coordinates calculated by the spiral calculation means. The fastening device as described in any one of Claims 1-10. The measuring means works in the X-axis direction and the Y-axis direction and acts in the X-axis direction and the Y-axis direction, which are parallel to each of two orthogonal lines on a plane perpendicular to the insertion direction. Measure the force value, calculate the in-plane reaction force value according to the following formula (1) and send it to the control means,
In-plane reaction force value = (X-axis direction reaction force value ² + Y-axis direction reaction force value ² ) ^0.5 (1)
The fastening hole contact threshold is
3. A value larger than a maximum value of the in-plane reaction force value measured by moving a predetermined distance in a spiral shape under a condition that a fastening part does not enter the fastening hole in advance. Fastening device.   The misjudgment exclusion threshold was measured by moving the fastening part while calculating the target coordinates so that the in-plane reaction force value was reduced under the condition that a part of the fastening part was already in the fastening hole. The fastening device according to claim 9, wherein the fastening device is an arbitrary value among values smaller than an average value of the in-plane reaction force values and larger than 0.   The fastening device according to claim 11, wherein the origin approach threshold is half of a distance between adjacent circumferences of the spiral track. A fastening method for inserting and fastening a fastening part into a fastening hole,
A spiral search step of calculating coordinates on a plane perpendicular to the insertion direction among the target coordinates so that the moving locus of the fastening parts is a spiral path, and moving the fastening parts to the target coordinates;
Measure the reaction force value that the fastening component receives in a plane perpendicular to the insertion direction, calculate the coordinates on the plane perpendicular to the insertion direction among the target coordinates so that the reaction force value is small, and Including a force control search step of moving to the target coordinates,
Compare the reaction force value and a preset fastening hole contact threshold,
If the reaction force value is smaller than the fastening hole contact threshold, execute the spiral search step,
If the reaction force value is larger than the fastening hole contact threshold, the force control search step is executed.

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