KR20170103811A - Robot system - Google Patents

Abstract

A retaining shaft (11) having a distal end formed in a shape complementary to a head (8a) of a male screw (8) and adapted to engage with a head of the male screw to fix a positional relationship about the axis of the male screw to the male screw, And a holding shaft driving unit (13) for rotating the holding shaft about the axis of the holding shaft, a robot main body (2) for holding the screw rotating mechanism and moving the screw rotating mechanism, And a robot controller (3) for controlling the holding axis driving unit as an external axis for performing a work in cooperation with the robot body.

Description

Robot System {ROBOT SYSTEM}

The present invention relates to a robot system.

[0002] An apparatus for screwing a robot by a robot is known from the prior art (see, for example, Patent Document 1).

The apparatus includes a nut runner controlled by a robot main body and a nut runner control unit, a robot connected to the robot main body and a nut runner control unit and outputting a command signal to the robot main body and the nut runner control unit to control the nut runner through the nut runner control unit And a control unit. Therefore, screwing can be done automatically.

Japanese Unexamined Patent Publication No. 2002-331428

On the other hand, it has recently been required to more rapidly and finely fasten a screw by a robot. However, in the conventional apparatus, there is a problem that it is difficult to cooperate with the nut runner and the robot in a fast and concurrent manner.

In order to solve the above problems, a robot system according to a certain aspect of the present invention has a tip formed in a shape complementary to a head of a male screw and engaged with a head of the male screw, (Holding shaft) in which a positional relationship around the axial line of the male screw is fixed, and a holding shaft driving section for rotationally driving the holding shaft about the axis of the holding shaft, and a screw driving mechanism And a robot controller for controlling the robot main body and controlling the holding axis driving unit as an external axis for performing an operation in cooperation with the robot main body.

According to this configuration, since the robot controller for controlling the robot body also controls the holding axis driving unit, communication by a predetermined protocol for exchanging between the two controllers as in the prior art becomes unnecessary, and the robot body and the screw- It is possible to reduce the delay in the cooperative operation with the apparatus. Thus, the screwing operation can be performed at high speed and at the same time.

Further, the configuration of the screw-turning mechanism can be simplified, and it is advantageous in manufacturing and also in manufacturing cost.

The robot body may be a multi-joint robot.

According to this configuration, it is possible to control the screw tightening robot while controlling the articulated robot.

Wherein the robot controller controls at least one of a rotation angle position and a rotation speed of the holding shaft when performing a clamping operation of the male screw engaged with the holding portion (holding portion), and the holding axis driving portion controls the holding The screw driving mechanism may be controlled so as to stop the rotation drive of the holding shaft in accordance with the determination whether or not the current for the shaft rotation driving has reached the limit current corresponding to the target torque.

According to this configuration, since the tightening torque of the screw is detected by using the driving current of the holding shaft driving unit as the outer shaft of the robot controller, the tightening of the screw can be made finer, and a dedicated torque sensor is not required.

Further comprising a torque sensor connected to the robot controller and having an engaging portion engaged with the retaining shaft and detecting a load torque of the engaging portion, The controller moves the retaining shaft to engage the retaining shaft with the engaging portion so as to supply a predetermined current to the retaining shaft driving unit. The controller controls the current to be supplied to the load detected by the torque sensor The table may be created in association with the torque, and the limiting current may be calculated based on the table.

According to this configuration, it is possible to automatically prevent the deviation of the actual tightening torque from the target tightening torque of the screw.

Wherein the robot controller is configured to start the insertion operation at the insertion operation start position of the male screw when the male screw is screwed into the female screw hole corresponding to the male screw and then the male screw is inserted into the female screw While the male screw is positioned at the reference position between the position and the insertion operation end position, the holding shaft driving unit may be controlled such that the rotation speed is higher than the rotation speed from the reference position to the insertion operation end position.

According to this configuration, fastening of the screw can be performed quickly.

Wherein the holding shaft is capable of receiving a rotational force with respect to the holding axis driving unit and is movable relative to the holding axis by a predetermined distance in the axial direction of the holding axis, and the holding axis is supported by the holding axis driving unit in the direction from the base end to the tip And a position detecting unit for detecting a position of the holding shaft relative to the holding shaft driving unit in the axial direction of the holding shaft.

According to this configuration, since the screw can be screwed while the holding shaft driving part is in a predetermined position during screw fastening, the control by the robot controller can be simplified.

According to an aspect of the present invention, there is provided a method of controlling a robot system, the method including the steps of: forming a tip end of the tip end portion of the tip end of the male screw in a complementary shape to engage with the head portion of the male screw, A screw rotation mechanism having a holding shaft for fixing a positional relationship around the axial line of the male screw and a holding shaft driving unit for rotationally driving the holding shaft about the axis of the holding shaft; And a robot controller for controlling said holding axis driving unit as an external axis for controlling said robot body and cooperating with said robot body to perform an operation, said robot controller comprising: When performing the tightening operation of the male screw, controlling at least one of the rotation angle position and the rotation speed of the holding shaft Consists of a group holding shaft drive section to control the screw turning mechanism current for driving the rotation axis is maintained to stop the holding axis rotation drive based on the determination of whether to limit a current corresponding to the target torque is reached.

According to this configuration, since the tightening torque of the screw is detected by using the driving current of the holding shaft driving unit as the outer shaft of the robot controller, the tightening of the screw can be made finer, and a dedicated torque sensor is not required.

Further comprising a torque sensor connected to the robot controller and having an engaging portion engaging with the retaining shaft and detecting a load torque of the engaging portion, wherein the robot controller moves the retaining shaft to engage with the retaining shaft, And a current is supplied to the holding shaft driving unit and the current is related to the load torque detected by the torque sensor to create the table and the limiting current may be calculated based on the table.

According to this configuration, it is possible to automatically prevent the deviation of the actual tightening from the target tightening torque of the screw.

The robot controller is characterized in that when the male screw and the hole of the female screw corresponding to the male screw are inserted and then the male screw is inserted into the female screw, The holding axis driving unit may be controlled such that the speed is higher than the rotational speed from the reference position to the piercing end position while the male screw is located at the reference position

According to this configuration, fastening of the screw can be performed quickly.

The present invention has the effect of enabling the screw turning operation to be done quickly and finely.

Fig. 1 is a view schematically showing a configuration example of a robot system according to Embodiment 1 of the present invention. Fig.
Fig. 2 is a sectional view of the main part showing a configuration example of a screw-turning mechanism of the robot system of Fig. 1
3 is a block diagram schematically showing an example of the configuration of a robot controller of the robot system of Fig.
4A is a flowchart showing an example of the operation of the robot system of FIG.
4B is a flowchart showing an example of the operation of the robot system of FIG.
4C is a flowchart showing an operation example of the robot system of FIG.
4D is a flowchart showing an example of the operation of the robot system of FIG.
Fig. 5A is a diagram showing an example of the operation of the robot system of Fig. 1, and shows an example of the operation of the screw removing operation.
Fig. 5B is a view showing an example of the operation of the robot system shown in Fig. 1, and shows an example of the operation of the screw removing operation.
Fig. 5C is a diagram showing an example of the operation of the robot system of Fig. 1, showing an example of the operation of the screw removing operation.
FIG. 6A is a diagram showing an example of the operation of the robot system of FIG. 1, and shows an example of the operation of the temporary tightening operation.
Fig. 6B is a view showing an example of the operation of the robot system of Fig. 1, and shows an example of the operation of the temporary tightening operation.
FIG. 6C is a view showing an example of the operation of the robot system of FIG. 1, and shows an example of the operation of the temporary tightening operation.
FIG. 6D is a view showing an example of the operation of the robot system of FIG. 1, and shows an example of the operation of the temporary tightening operation.
Fig. 7A is a diagram showing an example of the operation of the robot system shown in Fig. 1, and shows an example of the operation of the tightening operation. Fig.
Fig. 7B is a view showing an example of the operation of the robot system shown in Fig. 1, and shows an example of the operation of the tightening operation.
8 is a graph showing changes in the current value output to the holding axis driving unit detected by the current detecting unit of the servo amplifier and a change in the holding axis position detected by the holding axis position detecting unit in the operation example of the robot system in Fig. , And a change in temporary tightening operation.
FIG. 9 is a graph showing a change in current value output to the holding axis driving unit detected by the current detecting unit of the servo amplifier and a change in the holding axis position detected by the holding axis position detecting unit in the operation example of the robot system of FIG. 1, FIG. 5 is a graph showing a change in the tightening operation. FIG.
10 is a diagram schematically showing a configuration example of a control method of a robot system according to Embodiment 2 of the present invention.
11 is a block diagram schematically showing a configuration example of the robot controller of the method of controlling the robot system of Fig.
12 is a view showing a limiting current calculation table of the control method of the robot system in Fig.

 (Points of view of the present invention)

The present inventors eternally studied the fastening of the screw by the robot in a fast and precise manner. In the prior art, the following drawbacks exist.

Screw tightening operations generally include temporary tightening and tightening, adjusting the speed of rotation when screwing into the screw holes, and tightening torque management. Specifically, when two articles are fastened using a plurality of screws, a plurality of screws are temporally tightened and then main tightened to uniformly distribute the fastening force. In this case, the nut runner is sequentially screwed to the plurality of screw fastening portions by the robot, but in order to do so, the robot notifies the nut runner that the screw fastening portion has been reached every time the screw fastening is performed, It is necessary for the nut runner to notify the robot that it is finished. When the screw is inserted into the screw hole, the screw is inserted into the screw hole at a low rotational speed so as to surely align the axis of the screw with the center axis of the screw hole, And tighten the screws. In this case, as the screw tightening progresses, the screw advances. If the nut runner is moved by the robot in order to follow the socket, which is the transmitting portion of the rotational force of the screw, to the forward movement of the screw in the nut runner, information on the advancing of the screw (rotational speed, Screw position, etc.) in real time to the robot. Further, the tightening torque is managed to secure the quality of screw tightening. In this case, however, the nut runner needs to detect the tightening torque and notify the robot that it is within the allowable range.

As described above, when the nut runner is mounted on the robot and the screw tightening operation is performed, it is necessary that the nut runner and the robot cooperate.

However, the nut runner and the robot are controlled by separate controllers, and commands and data between the two controllers are exchanged by communication using a predetermined protocol. Therefore, it takes time to exchange commands and data between the two controllers, so it is difficult to quickly and simultaneously cooperate with the nut runner and the robot.

In order to overcome the disadvantages of the prior art, the inventors of the present invention have found that, due to the tip being formed in a shape complementary to the head of the male screw and engaging with the head of the male screw, the positional relationship And a holding shaft driving unit for rotating the holding shaft about the axis of the holding shaft, a robot main body holding the screw rotating mechanism and moving the screw rotating mechanism, And a robot controller for controlling the main body and controlling the holding axis driving unit as an external axis for performing a work in cooperation with the robot main body.

According to the present invention, since the robot controller for controlling the robot body also controls the holding axis driving unit, communication by a predetermined protocol for exchanging between two controllers as in the prior art becomes unnecessary, It is possible to reduce the delay in the cooperative operation with the apparatus. Therefore, the screwing operation can be performed quickly and finely. Further, the configuration of the screw-turning mechanism can be simplified, which is advantageous in manufacturing and low in manufacturing cost.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments. In the following description, the same or similar elements are denoted by the same reference numerals throughout the drawings, and redundant description thereof is omitted.

(Embodiment 1)

Fig. 1 is a view schematically showing a configuration example of a robot system 100 according to Embodiment 1 of the present invention.

The robot system 100 can be used for screw tightening.

As shown in Fig. 1, the robot system 100 includes a screw-turning mechanism 1, a robot body 2, and a robot controller 3.

[Robot body]

The robot body 2 is, for example, a multi-joint type industrial robot (articulated robot). The robot main body 2 has a base portion 21, a polyarticular arm 22 and an arm driving portion 23 (see Fig. 3).

The base 21 is provided on a placement surface of a floor or the like and supports the arm 22.

The arm 22 is rotatably connected to the base 21, for example, with a proximal end having a plurality of joints.

The arm drive unit 23 drives the joint shaft of the arm 22 to move the screw-driving mechanism 1 so that the screw-driving mechanism 1 is positioned at a predetermined position in the operation area by rotationally driving the drive shaft. The arm drive section 23 includes an encoder 23e (see FIG. 3) that detects the rotation angle position and the rotation speed of the drive shaft of the arm drive section 23.

[Screw rotation mechanism]

Fig. 2 is a sectional view showing the main part of the screw-driving mechanism 1 of the robot system 100. Fig.

2, the screw-turning mechanism 1 includes a holding shaft 11 and a holding shaft driving unit 13. [ In the present embodiment, the screw-turning mechanism 1 is provided with a shaft support portion 12, a holding shaft position detecting portion 14, and a supporting frame 15.

The holding shaft 11 has an engagement portion 11a which is engaged with the head portion 8a of the male screw 8 at the distal end portion. The engagement portion 11a is formed in a convex shape of, for example, a substantially regular hexagon when viewed in the extending direction of the axis L1 of the holding shaft 11. A substantially regular hexagonal groove is formed in the head 8a of the male screw 8 as viewed in the axial direction of the male screw 8 and is formed in a shape complementary to the engaging portion 11a. That is, the engaging portions 11a and the head portions 8a of the male screw 8 can be engaged with each other by matching the angular positions (phases) around the axis line and the axis L1. The relative positional relationship about the axis of the male screw 8 with respect to the male screw 8 is fixed by engaging the engaging portion 11a with the head 8a of the male screw 8. [ The holding shaft 11 is formed in a plurality of arrangements in accordance with the type of the male screw 8 to be used so that the engaging portion 11a of the holding shaft 11 has a shape corresponding to the shape of the head 8a of the male screw 8. [ do.

The holding shaft 11 also has a connecting portion 11b which is detachably attached to a distal end portion of a shaft supporting portion 12 which will be described later.

The holding shaft 11 is a magnet and is configured to pull the male screw 8 made of a magnetic material. The male screw 8 can be engaged with the holding shaft 11 by engaging the head portion 8a of the male screw 8 with the engaging portion 11a.

The shaft supporting portion 12 supports the holding shaft 11 and transmits the rotational driving force of the holding shaft driving portion 13 to the holding shaft 11. [ In this embodiment, the shaft support portion 12 has a fixed shaft 31, a movable shaft 32, and a spring 33. [

The fixed shaft 31 is formed into a rod shape extending in the extending direction of the axis L1.

The movable shaft 32 is formed into a rod shape extending in the extending direction of the axis L1. The movable shaft 32 has a connecting portion 32a at its tip end. The connecting portion 32a is detachably attached to the connecting portion 11b of the holding shaft 11 so that the holding shaft 11 can be exchanged in a shape corresponding to the type of the male screw 8 used by the shape of the engaging portion 11a .

The connecting portion 11a of the movable shaft 32 and the holding shaft 11 are provided so that the connecting portion 11b of the holding shaft 11 is provided at the connecting portion 32a of the movable shaft 32, And the relative positional relationship around the axis L1 is fixed. Therefore, when the movable shaft 32 is rotated, the holding shaft 11 is also rotated.

The movable shaft 32 also has an engagement concave portion 32b at its base end. The engaging concave portion 32b is fitted to the distal end portion of the fixed shaft 31 when viewed in the extending direction of the axial line L1 and is configured to be slidable in the extending direction of the axial line L1 with respect to the fixed shaft 31. [ The retaining shaft 11 moves in the direction toward the base end from the tip end of the retaining shaft 11 of the axis L1 at the first position P1 and the first position P1, And a second position P2 which is close to the second position P2. That is, the holding shaft 11 is configured so as to be able to receive rotational force with respect to the holding shaft driving unit 13, and to move relative to the holding axis 11 in the axial direction of the holding shaft 11.

The engaging concave portion 32b of the movable shaft 32 is formed in a shape complementary to the distal end of the fixed shaft 31 when viewed in the direction of extension of the axis L1 and is movable in the axial direction of the movable shaft 32, Is configured such that the relative positional relationship around the axis L1 is fixed. Concretely, the engaging concave portion 32b and the distal end portions of the fixed shaft 31 are formed to have a noncircular shape (for example, a polygonal shape, a circular shape having a concavo-convex shape on the outer periphery) to fit with a small gap therebetween. Therefore, when the fixed shaft 31 is rotated, the movable shaft 32 and the holding shaft 11 rotate together with the fixed shaft 31. [

The spring 33 is a compression coil spring and is fitted to the fixed shaft 31 so as to be located between the proximal end of the fixed shaft 31 and the proximal end of the movable shaft 32, And is in contact with the proximal end of the fixed shaft 31 and the proximal end of the movable shaft 32. The spring 33 urges the proximal end of the fixed shaft 31 and the proximal end of the movable shaft 32 to be separated from each other. Therefore, in the steady state, the movable shaft 32 is configured to be positioned at the first position P1, and due to the retention shaft 11 being pushed from the first position P1 to the second position P2, the spring 33 The retaining shaft 11 is moved from the first position P1 to the second position P2 against the urging force of the retaining shaft 11.

Further, the spring 33 is not limited to the compression coil spring. For example, the movable shaft 32 is configured to be positioned at the first position P1 in the steady state by using the tension coil spring, and the holding shaft 11 is moved from the first position P1 to the second position P2 The retaining shaft 11 may be moved from the first position P1 to the second position P2 against the urging force of the spring 33. As a result, Further, the spring 33 is not limited to the coil spring, but may be a gas spring.

In the first position P1, the movable shaft 32 located at the first position P1 is in contact with the guide portion 15a of the support frame 15 or its vicinity, and in the direction of the axis L1 , And is regulated so as not to move from the second position (P2) to the first position (P1).

The holding shaft driving unit 13 drives the holding shaft 11 to rotate about the axis L1 via the shaft supporting unit 12. [ The holding axis driving unit 13 is, for example, a servo motor. The driving shaft 13a of the holding shaft driving unit 13 is fixedly connected to the base end of the fixed shaft 31. [ Accordingly, the holding shaft driving unit 13 rotates the fixed shaft 31, the movable shaft 32, and the holding shaft 11 by the driving force, thereby screwing the male screw 8 engaged with the holding shaft 11 It is configured to be able to work. The drive shaft 13a has an encoder 13e (see Fig. 3) for detecting the angular position and rotational speed of the drive shaft 13a.

The support frame 15 is formed, for example, in a cylindrical shape and is fitted to the outside of the fixed shaft 31 and the movable shaft 32. The proximal end of the supporting frame 15 supports the holding shaft driving part 13. [ The driving shaft 13a and the fixed shaft 31 of the holding shaft driving unit 13 are fixed so that the distance between the supporting frame 15 and the fixed shaft 31 in the extending direction of the axis L1 The relative positional relationship is fixed.

The retention shaft position detection unit 14 detects the position relative to the retention shaft 11 support portion 12 in the extending direction of the axis L1.

The guide portion 15a is provided so as to be interposed between the distal end of the support frame 15 and the movable shaft 32. [ The guide portion 15a guides the movable shaft 32 movably in the axial direction of the axis L1 with respect to the support frame 15 and rotatably guides around the axial line L1.

The holding axis position detecting section 14 has, for example, a sensor body 41 as a laser displacement gauge, a reflecting plate 42, and a reflecting plate supporting section 43.

The sensor main body 41 irradiates a laser beam onto the reflection plate 42 disposed on the axis L2 extending in parallel to the axis L1 and reflects the laser beam to the reflection plate 42 42) of the vehicle. The sensor main body 41 is provided on the support rim 15. Therefore, the relative positional relationship of the sensor main body 41 in the extending direction of the axis L1 with respect to the fixed shaft 31 is fixed.

The reflection plate 42 is disposed on the axis L2 and is provided on the support frame 15 via the reflection plate support 43. [

The reflector support portion 43 includes a support shaft 43a, a support shaft connection portion 43b, and a support shaft guide portion 43c. The support shaft 43a extends along an axis L2 extending parallel to the axis L1 and a reflector 42 is provided at the base end. The support shaft connecting portion 43b is provided on the movable shaft 32 through a bearing. Therefore, the support shaft connecting portion 43b is configured to rotate relative to the movable shaft 32 about the axis L1. On the other hand, the support shaft connecting portion 43b is fixed to the movable shaft 32 so as not to move in the extending direction of the axis L1. The tip of the support shaft 43a is provided in the support shaft connection portion 43b. The support shaft guide portion 43c is fixed to the support frame 15. [ The support shaft guide portion 43c has a shaft hole having the same axis as the axial line L2 and a support shaft 43a is inserted into the insertion hole 43a ). Therefore, the support shaft guide portion 43c is configured to guide the support shaft 43a in the extending direction of the axis L2. On the other hand, the support shaft guide portion 43c restricts the support shaft 43a from moving in a plane perpendicular to the extending direction of the axis L2.

As described above, the support shaft connecting portion 43b is fixedly mounted on the movable shaft 32 so as not to move in the extending direction of the axis L1. Further, the support shaft guide portion 43c is mounted on the support shaft When the holding shaft 11 and the movable shaft 32 move relative to the supporting frame 15 in the extending direction of the axial line L1, The support shaft connecting portion 43b, the support shaft 43a and the reflecting plate 42 together with the holding shaft 11 and the movable shaft 32 move relative to the supporting frame 15 in the extending direction of the axis L1 do. Since the sensor main body 41 is provided on the support frame 15 as described above, the sensor main body 41 does not move as the retaining shaft 11 and the movable shaft 32 move. The distance between the sensor main body 41 and the reflection plate 42 in the extending direction of the axis L1 is changed and the sensor main body 41 detects the change in the distance. That is, the holding axis position detecting unit 14 is configured to detect the position of the holding axis 11 relative to the holding axis driving unit 13 in the extending direction of the axis L1.

As described above, the support shaft connecting portion 43b is configured to relatively rotate about the axis L1 with respect to the movable shaft 32, and the support shaft guide portion 43c is configured such that the support shaft 43a is rotatable about the axis L1 Even if the movable shaft 32 rotates about the axis Ll, the reflection plate 42 and the reflection plate support portion 43 are prevented from moving relative to the movable shaft 32 So as not to rotate together. Therefore, the reflection plate 42 is prevented from deviating from the axis L2.

[Robot Controller]

3 is a block diagram schematically showing the configuration of the robot controller 3. As shown in Fig. Hereinafter, the control system of the robot system 100 will be described with reference to FIG.

The robot controller 3 is disposed around the robot main body 2 and performs position control, speed control, or current control of a joint shaft of the robot main body 2 and a control target shaft other than the robot main body 2. A control target shaft other than the robot main body 2 constitutes the outer axis of the robot controller 3. [ In this embodiment, the robot controller 3 controls the drive shaft 13a of the holding axis driving unit 13 as an external axis. The robot controller 3 can also control the driving shaft 13a of the holding shaft driving unit 13 of the screw rotation mechanism 1 so as to control the joint shaft of the robot main body 2. [ That is, when a person operating the robot main body 2 sees the robot main body 2, it is possible to control the screw-turning mechanism 1 by using the same operation command as that for the robot main body 2, The screw tightening robot can be controlled. Therefore, the configuration of the robot system 100 can be simplified as compared with the case where the screw-turning mechanism 1 operates according to the operation command of the user. Therefore, it is advantageous in manufacturing and also in manufacturing cost. Hereinafter, the configuration of the robot controller 3 will be described in detail.

The robot controller 3 includes a control section 51 having a computing unit such as a CPU and a storage section 54 having a memory such as ROM and RAM and a storage section 54 corresponding to the arm drive section 23 and the hold axis drive section 13 And a servo amplifier 52 are provided.

The control unit 51 determines the target angular position, the target rotation speed or the target torque and controls the driving of the arm driving unit 23 and the holding axis driving unit 13 through the servo amplifier. The control unit 51 may be constituted by a single control apparatus that performs centralized control, or may be constituted by a plurality of controllers that perform distributed control in cooperation with each other.

The servo amplifier 52 performs servo control of the arm driving unit 23 and the holding axis driving unit 13, which are servo motors. That is, the servo amplifier 52 performs the tracking control so that the deviation from the target angular position, the target rotation speed or the target torque determined by the control unit 51 is zero. The servo amplifier 52 includes a current detector (not shown) for detecting a current value output to the arm driver 23 and the holding axis driver 13.

Rotation angular position information and rotational speed information output from the encoder 23e (see FIG. 3) of the arm driving section 23 and the encoder 13e of the holding axis driving section 13 and rotational angular position information and rotational speed information outputted from the holding axis position detecting section 14 The position information of the holding shaft 11 is input to the control unit 51. [ The current value information of the current outputted from the servo amplifier 52 to the arm drive section 23 and the hold axis drive section 13 detected by the current detection section of the servo amplifier 52 is also inputted to the control section 51. [

A predetermined control program is stored in the storage unit 54, and the operation of the screw-turning mechanism 1 and the robot body 2 is controlled by the control unit reading and executing the control program. The storage unit 54 stores the current value outputted to the holding axis driving unit 13 in the servo amplifier 52 and the limiting current calculation indicating the relationship between the clamping torque of the holding axis driving unit 13 corresponding to the current value And the table T is stored.

The storage section 54 is also connected to the storage section 54 so that the screw removal approach position Pa, the screw removal position Pb, the screw removal retreat position Pc, and the temporary tightening approach position Pf of the screw- The position Pg, the main tightening approach position Ps and the main tightening position Pt are stored. The storage section 54 stores a third position P3, a fifth position P5 and a sixth position P6 of the holding shaft 11.

[Operation example]

Next, an operation example of the robot system 100 will be described.

4A is a flowchart showing an example of the operation of the robot system 100 in the embodiment of the present invention.

4A, the control unit 51 moves the screw-driving mechanism 1 to rotate the screws (not shown) that hold (hold) the male screw 8 on the holding shaft 11 (Step S1). For example, the male screw 8 is inserted into the insertion hole 110a of the screw mount 110 (see Fig. 6A) and held in the screw mount 110. Fig. The insertion hole 110a is formed to have a diameter slightly larger than the diameter of the screw shaft of the male screw 8 so that the male screw 8 can be easily pulled out.

When the male screw 8 is held in the holding shaft 11 and then the male screw 8 is carried to the position where the female screw hole 9 to be fitted with the male screw 8 is provided, (Step S2).

Next, the main tightening operation is performed by joining the male screw 8 with a predetermined tightening torque (step S3). Thereafter, the screw-driving mechanism 1 may be moved to an arbitrary retreat position. Hereinafter, the screw removing operation, temporary tightening operation, and main tightening operation will be described in detail.

<Screw removal operation>

Fig. 4B is a flowchart showing an example of the operation of the robot system 100, which explains the screw removal operation.

5A to 5C are diagrams showing an example of the operation of the robot system 100. Fig.

First, as shown in Fig. 5A, the control unit 51 controls the robot main body 2 to position the screw-turning mechanism 1 at the screw removal approach position Pa (step S11). The screw removal approach position Pa is a position where the engagement portion 11a of the holding shaft 11 is opposed to the head portion 8a of the male screw 8 held in the screw holder 110, And the axis L1 of the retaining shaft 11 coincides with the axis of the retaining shaft 11.

5B, the control unit 51 controls the robot main body 2 to move the screw-driving mechanism 1 along the axis L1, and the screw-turning mechanism 1 (Step S12). The screw removal position Pb is a position at which the retaining shaft 11 approaches the male screw 8 in the extending direction of the axis L1 of the screw removal approaching position Pa And the angular positions of the engaging portion 11a of the retaining shaft 11 and the head 8a of the male screw 8 coincide with each other about the axis L1 of the retaining shaft 11, 33 at a third position P3 which is slightly pushed in the direction from the first position P1 to the second position P2.

Since the angular position around the axis of the male screw 8 is set at random at the time of setting the male screw 8 on the screw holder 110, the engaging portion 11a of the holding shaft 11 and the male screw 8, There is a possibility that the angular positions around the axis L1 of the head portion 8a of the first lens group 8 do not coincide with each other. 5C, the engagement portion 11a of the holding shaft 11 of the screw rotation mechanism 1 located at the screw removal position Pb is engaged with the groove 8a of the head 8a of the male screw 8 Groove 8a and is pushed in the direction from the first position P1 to the second position P2 more than the third position P3.

Next, based on the positional information of the holding shaft 11 outputted from the holding shaft position detecting unit 14, the control unit 51 determines whether or not the holding shaft 11 is located at the third position P3 Step S13). As described above, when the engagement portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 are engaged with each other, the holding shaft 11 is positioned at the third position P3. On the other hand, when the holding shaft 11 and the male screw 8 are not engaged with each other, the holding shaft 11 is moved in the direction from the first position P1 to the second position P2 more than the third position P3 (D1). Therefore, it is possible to determine whether or not the engaging portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 are engaged with each other by performing the determination.

If the control section 51 determines that the holding shaft 11 is not located at the third position P3 (No at step S13), the control section 51 rotates the holding shaft 11 Step S14). At this time, when the angular positions of the engagement portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 coincide with each other about the axis L1, the pressing force of the spring 33 pushes the holding shaft 11, The engaging portion 11a of the male screw 8 is pushed into the groove of the head 8a of the male screw 8 so that the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 engage with each other. And again determines whether the retaining axis 11 is located at the third position P3. That is, the holding shaft 11 is rotated until the angular positions around the axis L1 of the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 coincide with each other. The retaining shaft 11 and the male screw 8 can be engaged with each other. When the holding shaft 11 and the male screw 8 are engaged with each other, the holding shaft 11, which is a magnet, pulls the male screw 8 made of a magnetic material so that the holding shaft 11 is held by the male screw 8.

If the control unit 51 determines that the holding shaft 11 is located at the third position P3 (Yes in step S13), the control unit 51 sets the screw-turning mechanism 1 to the screw removal retreat position Pc) (step S15). Thus, the male screw 8 is detached from the screw holder 110. Then, the screw removing operation is finished.

<Temporary fastening operation>

4C is a flowchart showing an example of the operation of the robot system 100, and the temporary tightening operation is described.

6A to 6D are diagrams showing an example of the operation of the robot system 100. Fig.

8 shows an example of operation of the robot system 100 in which the change in the current value output to the holding axis driving section 13 detected by the current detecting section of the servo amplifier 52 and the change in the current value detected by the holding axis position detecting section 14 FIG. 7 is a graph showing changes in position of the holding shaft 11, and is a graph showing a change in the temporary tightening operation. FIG.

6A, the control unit 51 controls the robot main body 2 to rotate the screw-driving mechanism 1 in which the male screw 8 is held on the holding shaft 11 at the temporary tightening approach position Pf, (Step S21). The temporary tightening approach position Pf is set at a position where the tip of the male screw 8 held by the holding shaft 11 is opposed to the end of the female screw hole 9 and at the same time the female screw hole 9 And the axial line L1 of the holding shaft 11. [0064] As shown in Fig.

6B, the control unit 51 controls the robot main body 2 to move the screw-driving mechanism 1 along the axis L1 to move the screw-driving mechanism 1 to the temporary tightening position Pg, (Step S22). The temporary tightening position Pg is a position in which the male screw 8 is located on the side closer to the female screw hole 9 from the base end to the tip end of the holding shaft 11 in the extending direction of the axis L1 of the temporary tightening approach position Pf, And the end of the male screw 8 held by the holding shaft 11 and the end of the female screw hole 9 are in contact with each other. In this state, the temporary tightening position Pg is configured such that the retaining shaft 11 is largely pushed in the direction from the first position P1 to the second position P2 against the urging force of the spring 33 . This position is preferably configured so that the distance from the first position P1 is longer than the length of the threaded portion of the threaded shaft of the male screw 8. [ The control unit 51 stores the position of the holding shaft 11 in the direction of the axis L1 of the holding shaft 11 input from the holding shaft position detecting unit 14 in the storage unit 54 as the fourth position P4.

Next, the control section 51 drives the holding axis driving section 13. The holding shaft 11 is rotated at a low speed in the fastening direction of the male screw 8 (step S23). This is a hooking operation in which the male screw (8) and the female screw hole (9) are fitted. At this time, the control unit 51 controls at least one of the rotation angle position and the rotation speed of the holding shaft 11. [

When the angular position of the tip of the thread of the male screw 8 and the axial end of the tip of the screw groove of the female screw hole 9 coincide with each other and the male screw 8 and the female screw hole 9 are fitted The male screw 8 enters the female screw hole 9. The difference between the position of the holding shaft 11 input from the holding shaft position detecting unit 14 and the fourth position P4 is increased.

Next, the control unit 51 determines whether or not the difference (displacement) between the position of the holding shaft 11 input from the holding shaft position detecting unit 14 and the fourth position P4 is greater than a predetermined value, (Step S24) at a low speed in the tightening direction of the male screw 8. It is preferable that the predetermined value is set to a value corresponding to the depth dimension of the insertion when the male screw 8 and the female screw hole 9 are reliably fitted. For example, when the screw pitch of the male screw 8 is 1 / 2 &lt; / RTI &gt;

As described above, since the holding shaft 11 is urged by the spring 33 from the second position P2 toward the first position P1, the male screw 8 goes into the female screw hole 9 The retaining shaft 11 is configured to move from the second position P2 to the first position P1 in accordance therewith. The engaging state between the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 is maintained even when the female screw hole 9 is disengaged from the screw screw mechanism 1. [ Therefore, the screw can be fastened with the screw-turning mechanism 1 in a predetermined position. Therefore, the contents of control by the robot controller 3 can be simplified. In addition, the position (rotation angle position) of the male screw 8 when the male screw 8 and the female screw hole 9 are fitted constitutes the insertion operation start position.

Next, when the male screw 8 is caught by the female screw hole 9, the control unit 51 rotates the retaining shaft 11 at the speed V1 (see Fig. 8) in the tightening direction of the male screw 8 (step S25). At this time, the control unit 51 controls at least one of the rotational angle position and the rotational speed of the holding shaft 11.

Next, as shown in Fig. 6C, the controller 51 rotates the retaining shaft 11 at the speed V1 until the retaining shaft 11 is located at the fifth position P5 (step S26). For example, the rotation angle position of the holding shaft 11 or the axis L1 of the holding shaft 11 inputted from the holding shaft position detecting portion 14, that is, the position where the holding shaft 11 is positioned at the fifth position P5, ) Direction.

When the control unit 51 determines that the holding shaft 11 is located at the fifth position P5, the control unit 51 rotates the holding shaft 11 at the speed V2 in the tightening direction of the head 8a (step S27 ). The speed V2 is lower than the speed V1 (see Fig. 8). At this time, the control unit 51 controls at least one of the rotation angle position and the rotation speed of the holding shaft 11. The position of the male screw 8 when the retaining shaft 11 is located at the fifth position P5 constitutes the reference position.

The control unit 51 controls the engagement of the male screw 8 with the reference position and the engagement of the male screw 8 and the female screw hole 9 in the insertion operation start position of the male screw 8 when the male screw 8 is inserted into the female screw hole 9. [ The rotation speed is higher than the rotation speed from the reference position to the end position of the insertion operation while the male screw is positioned. The fastening of the male screw 8 and the female screw hole 9 can be performed quickly.

Next, the control unit 51 determines whether or not the current Ir has reached the temporary tightening current threshold Ia (step S28). This determination is made as to whether or not the seating surface of the head 8a of the male screw 8 is seated, as shown in Fig. 6D. 8, when the seating surface of the head 8a of the male screw 8 is seated, the rotation speed of the male screw 8 rapidly decreases or the rotation of the male screw 8 stops. Therefore, the difference between the target rotation angle position or the target rotation speed and the present value is rapidly increased, and the servo amplifier 52, which performs the control of the holding axis driving section 13 by the position control or the speed control, Or the current supplied to the holding axis driving unit 13 to sharply reduce the deviation from the current value with respect to the target velocity. Therefore, the control unit 51 compares this value with the current value Ir by using the current threshold Ia set to a value capable of capturing the abruptly increasing current value so that the current value Ir is equal to the temporary throttle current threshold Ia , It can be determined whether or not the left and right surfaces of the head 8a of the male screw 8 are seated. The temporary tightening current threshold value Ia is set to be smaller than the main tightening current threshold value Ib to be described later. As a result, the male screw (8) is tightened with an excessive torque and the male screw (8) or the female screw hole (9) can be prevented from being damaged.

As described above, since the speed V2 is configured to be lower than the speed V1, it is possible to prevent the excessive movement of the head portion 8a of the male screw 8 from the seating position until the temporary tightening operation is completed It is possible to prevent the male screw 8 and the female screw hole 9 from being damaged by tightening the male screw 8 with the torque.

While the control unit 51 determines that the current value Ir does not reach the present tightening current threshold Ib (limit current) (No at step S28), the control unit 51 rotates the holding shaft 11 S27). When the current value Ir reaches the present tightening current threshold Ib (limit current) (Yes in step S28), the rotation of the holding shaft 11 is stopped (step S29). Further, the position (rotation angle position) of the male screw 8 when the rotation of the holding shaft 11 is stopped constitutes a position at which the insertion operation ends.

Therefore, when the male screw 8 is inserted into the female screw hole 9 after the male screw 8 and the female screw hole 9 are fitted into the female screw hole 9, While the male screw (8) is positioned at the reference position between the reference position and the insertion operation end position, the rotation speed is higher than the rotation speed from the reference position to the insertion operation end position.

Then, the temporary tightening operation is terminated.

<Main tightening operation>

4D is a flowchart showing an example of the operation of the robot system 100, and explains the tightening operation.

Figs. 7A and 7B are diagrams showing an example of the operation of the robot system 100. Fig.

9 is a graph showing the variation of the current value output to the holding axis driving unit 13 detected by the current detecting unit of the servo amplifier 52 in the operation example of the robot system 100 and the variation of the current value output from the holding axis detecting unit 14 FIG. 5 is a graph showing a change in the position of the clamping mechanism 11, and FIG.

First, as shown in Fig. 7A, the control unit 51 controls the robot main body 2 to position the screw-turning mechanism 1 at the main tightening approach position Ps (step S31). The tightening approach position Ps is a position where the engaging portion 11a of the retaining shaft 11 is opposed to the head 8a of the male screw 8 tightly fixed to the female screw hole 9, Axis and the axis L1 of the holding shaft 11 coincide with each other.

7B, the control unit 51 controls the robot main body 2 to move the screw-driving mechanism 1 along the axis L1 to move the screw-driving mechanism 1 to the original position Pt, (Step S32). The present tightening position Pt is a position at which the holding shaft 11 is moved toward the side closer to the male screw 8 (from the base end to the tip end of the holding shaft 11) in the extending direction of the axis L1 of the main tightening approach position Ps And the angular positions of the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 are aligned with each other about the axis L1 of the holding shaft 11, In a state of being pushed in the direction from the first position P1 to the second position P2 against the urging force of the male screw 8 in the sixth position P6.

Next, the control unit 51 executes steps S33 to S34, and engages the holding shaft 11 and the male screw 8. However, the operation is the same as the above-mentioned steps S13 to S14, and a description thereof will be omitted.

In addition, when the tightening operation is performed while the holding shaft 11 and the male screw 8 are engaged after the temporary tightening operation is completed, the above operation can be omitted.

Next, the control section 51 slowly rotates the holding shaft 11 in the tightening direction (step S35). At this time, the control unit 51 controls at least one of the rotation angle position and the rotation speed of the holding shaft 11. [

Next, the control unit 51 determines whether the current value Ir reaches the present tightening current threshold Ib (limit current) and whether the holding shaft 11 rotates (step S36). That is, the control unit 51 makes a determination that includes whether or not the current for rotating the holding shaft 11 by the holding shaft driving unit 13 has reached the main tightening current threshold Ib.

9, the main tightening current threshold Ib is a value that is a predetermined value and is based on a current value corresponding to a predetermined tightening torque of the male screw 8 to be. In the present embodiment, the tightening current threshold Ib corresponds to the tightening torque of the male thread 8, which has been prescribed in advance, with reference to the limiting current calculation table T stored in the storage section 54 by the control section 51 Is calculated. Therefore, the control unit 51 compares the main tightening current threshold Ib and the current value Ir to determine whether or not the current value Ir has reached the main tightening current threshold Ib, It is possible to judge whether or not the cover 8 is tightened. Further, in the present embodiment, since the control section 51 also determines whether or not the retaining shaft 11 is rotating, it is possible to judge whether or not the male screw 8 is tightened with the previously specified tightening torque more reliably have.

Since the robot system 100 detects the tightening torque of the male screw 8 by using the driving current of the holding shaft driving unit 13 as the outer shaft of the robot controller 3, it is possible to finely tighten the screw, The torque sensor of Fig.

Further, the control unit 51 can tighten the male screw 8 more accurately if it is determined at the same time whether or not the displacement of the retaining shaft 11 is not detected, in addition to the above-mentioned determination.

If the current value Ir does not reach the present tightening current threshold value Ib (limiting current) or the current value Ir reaches the present tightening current threshold value Ib (limiting current), the control section 51 maintains While the shaft 11 is judged to be rotating (No at step S36), the holding shaft 11 is rotated (step S35). When the current value Ir reaches the present tightening current threshold Ib (limit current) , And if it is determined that the retaining shaft 11 is not rotating (Yes at step S36), the rotation of the retaining shaft 11 is stopped (step S37). The rotation stop of the holding shaft 11 is achieved, for example, by setting the target rotation speed to zero. The control unit 51 controls the brake unit for stopping the rotation of the retaining shaft 11 and applies the brake to the retaining shaft 11 to rotate the retaining shaft 11 It may be stopped.

Then, the control unit 51 terminates the control of the holding shaft 11 and ends the main tightening operation.

Also, the control section 51 may rotate the retaining shaft 11 in the direction of relaxation before terminating the tightening operation. The engaging portion 11a of the holding shaft 11 can be easily removed from the groove of the head 8a of the male screw 8. [

As described above, in the robot system 100 of the present invention, since the robot controller 3 for controlling the robot body 2 controls the holding axis driving unit 13, the interaction between the two controllers It is possible to reduce the delay in the cooperative operation between the robot main body 2 and the screw driver 1. [ Thus, the screwing operation can be performed quickly and finely.

Further, the configuration of the screw-turning mechanism 1 can be simplified, which is advantageous in manufacturing and also in manufacturing cost.

(Embodiment 2)

10 is a diagram schematically showing a configuration example of the robot system 200 according to the second embodiment of the present invention. 11 is a block diagram schematically showing the configuration of the robot controller 3. As shown in Fig.

10, the robot system 200 includes a screw-turning mechanism 1, a robot main body 2, a robot controller 3, and a torque sensor 204. As shown in Fig. The configuration of the screw-turning mechanism 1, the robot main body 2, and the robot controller 3 is the same as that of the first embodiment, and the description thereof will be omitted.

The torque sensor 204 has an engaging portion 205 which engages with the retaining shaft 11 of the screw- The torque sensor 204 is configured to detect the load torque of the engaging portion 205. 11, the load torque value at which the torque sensor 204 is detected is input to the control section 51. [

 [Operation example]

Next, an operation example of the robot system 200 will be described.

First, the control section 51 controls the robot main body 2 to move the holding shaft 11 to engage the holding shaft 11 and the engaging section 205. At this time,

Next, the control unit 51 determines a first current value to be supplied to the holding axis driving unit 13, and controls the holding axis driving unit 13 to supply the current with the first current value. Thereby, the retaining shaft 11 rotates and the engaging portion 205 is tightened to a predetermined torque, so that the torque sensor 204 detects the load torque.

Next, the control unit 51 associates the load torque value detected by the torque sensor 204 with the first current value.

Then, the above operation is repeated to obtain the first to Nth current values, which are different current values, and the load torque value associated with these current values, respectively.

Then, an approximate expression is calculated based on the first to Nth current values and a load torque value associated with each of the current values, and this is determined by the limiting current calculation table T as shown in Fig. 12 .

In this manner, the robot system 200 can automatically prevent the deviation of the actual tightening torque from the target tightening torque of the screw.

(Embodiment 3)

In the first embodiment, the screw-turning mechanism 1 is configured such that the holding shaft 11 is urged from the second position P2 to the first position P1 by the spring 33, The retaining shaft 11 is configured to move from the second position P2 to the first position P1 in accordance therewith. Instead of this, when the robot main body 2 presses the holding shaft 11 from the second position P2 toward the first position P1 and the male screw 8 sinks in the female screw hole 9, The control unit 51 may control the robot main body 2 so that the retaining shaft 11 of the screw rotation mechanism 1 moves from the second position P2 toward the first position P1. At this time, instead of detecting the position of the holding shaft 11 by the holding shaft position detecting unit 14, the position of the holding shaft 11 of the screw driving mechanism 1 is detected based on the angle axis of the joint shaft of the robot main body 2 Or may be configured to detect the position.

With such a configuration, the screw turning operation can be performed more quickly and finely.

(Fourth Embodiment)

In the first embodiment, the holding shaft 11 is pressed by the spring 33 from the second position P2 to the first position P1. The holding shaft 11 may be pressed toward the first position P1 from the second position P2 by a driving force of a driving unit such as a servo motor. Accordingly, since the holding shaft 11 can be pressed by an arbitrary pressing force, the screw turning operation can be further finer.

(Embodiment 5)

The control unit 51 controls the screw rotation mechanism 1 and the robot main body 2 so as to replace the holding shaft 11 mounted on the movable shaft 32 with a shape corresponding to the type of the male screw 8. In this embodiment, As shown in Fig.

From the above description, many modifications and other embodiments of the invention are apparent to those skilled in the art. Accordingly, the above description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present invention.

Ia Temporary tightening current threshold
Ib Tightening Current Threshold
Ir current value
L1 axis
L2 axis
P1 1st position
P2 2nd position
P3 3rd position
P4 fourth position
P5 fifth position
P6 sixth position
Pa Screw removal access position
Pb Screw removal position
Pc Screw Removal Retraction Position
Pf temporary tightening access position
Pg Temporary tightening position
Ps Tightening Access Position
Pt main tightening position
T limit current calculation table
1 Screw-turning mechanism
2 Robot body
3 Robot controller
8 male threads
8a head
9 Female thread
11 Holding axis
11a
11b connection
12-
13 Holding axis driver
13a drive shaft
13e encoder
14 Holding axis position detector
15 Support Border
21 Foundation (base)
22 Cancer
23 arm drive
23e encoder
24 arm drive
31 Fixed Axis
32 movable shaft
32a connecting portion
32b engaging concave portion
33 spring
41 Sensor body
42 reflector
43 reflector support
43a support shaft
43b Support shaft connection
43c Support shaft guide part
51 control unit
52 Servo amplifier
54 memory unit
100 Robotic System
110 screw cradle
110a insertion hole
200 Robotic System
204 Torque sensor
205 engagement section

Claims (9)

A holding shaft having a tip end formed in a shape complementary to the head portion of the male screw and fixed to the head portion of the male screw to fix the positional relationship about the axis of the male screw with respect to the male screw, A screw-driving mechanism having a holding shaft driving part,
A robot main body holding said screw rotation mechanism and moving said screw rotation mechanism,
And a robot controller for controlling the robot main body and controlling the holding axis driving unit as an external axis for performing a work in cooperation with the robot main body.
The method according to claim 1,
Wherein the robot body is a articulated robot.
3. The method according to claim 1 or 2,
Wherein the robot controller controls at least one of a rotation angle position and a rotation speed of the holding shaft when performing a tightening operation of the male screw engaged with the holding portion and a current for rotating the holding shaft And controls the screw rotation mechanism to stop the rotation drive of the holding shaft in accordance with the determination as to whether or not the limit current corresponding to the target torque has been reached.
The method of claim 3,
Further comprising a torque sensor connected to the robot controller, the torque sensor having an engaging portion engaged with the holding shaft and detecting a load torque of the engaging portion,
The robot controller moves the holding shaft to engage the holding shaft with the engaging portion, controls the holding shaft to be supplied with a predetermined current, correlates the current with the load torque detected by the torque sensor, And calculates the limit current based on the table.
5. The method according to any one of claims 1 to 4,
Wherein the robot controller further comprises a reference position between the insertion operation start position and the insertion operation end position from the insertion operation start position of the male screw when the male screw is inserted into the female screw after fitting the male screw and the female screw hole corresponding to the male screw, And controls the holding axis driving unit so that the rotational speed becomes higher than the rotational speed from the reference position to the end position of the piercing operation while the male screw is located.
6. The method according to any one of claims 1 to 5,
Wherein the holding shaft is configured to be capable of receiving a rotational force with respect to the holding shaft driving unit and movable relative to the holding shaft at a predetermined distance in the axial direction of the holding shaft,
And a position detecting section for detecting a position of the holding shaft relative to the holding axis driving section in the axial direction of the holding shaft, The robot system comprising:
A holding shaft having a tip end formed in a shape complementary to the head portion of the male screw so as to be engaged with the head portion of the male screw to fix the positional relationship of the male screw around the axial direction of the male screw, A screw rotation mechanism having a holding shaft driving part for rotationally driving,
A robot main body holding said screw rotation mechanism and moving said screw rotation mechanism,
And a robot controller for controlling the robot main body and controlling the holding axis driving unit as an external axis for performing an operation in cooperation with the robot main body,
Wherein the robot controller controls at least one of a rotational angle position and a rotational speed of the holding shaft when performing a tightening operation of the male screw engaged with the holding portion, and the current for rotating the holding shaft by the holding- Wherein said control means controls said screw rotation mechanism to stop rotational driving of said holding shaft in accordance with determination as to whether or not a limit current corresponding to torque has been reached.
8. The method of claim 7,
Further comprising a torque sensor connected to the robot controller and having an engaging portion for engaging with the retaining shaft and detecting a load torque of the engaging portion,
The robot controller moves the holding shaft to engage the holding shaft with the engaging part, controls the holding shaft to be supplied with a predetermined current, correlates the current with the load torque detected by the torque sensor, And the limiting current is calculated based on the table.
9. The method according to claim 7 or 8,
Wherein the robot controller includes a reference position between the insertion operation start position and the insertion operation end position from the insertion operation start position of the male screw when the male screw is inserted into the female screw after fitting the female screw corresponding to the male screw and the male screw, Wherein the control unit controls the holding axis driving unit such that the speed of the holding shaft is higher than the rotating speed from the reference position to the end of the piercing operation while the male screw is located.

Images