WO2016103298A1

WO2016103298A1 - Robot system

Info

Publication number: WO2016103298A1
Application number: PCT/JP2014/006476
Authority: WO
Inventors: 潤竹林; 修平倉岡; 裕之水本; 山根　秀士
Original assignee: 川崎重工業株式会社
Priority date: 2014-12-25
Filing date: 2014-12-25
Publication date: 2016-06-30
Also published as: CN107000139A; KR20170103811A; JP6397510B2; KR101989122B1; JPWO2016103298A1; CN107000139B

Abstract

This robot system is equipped with: a screw-driving mechanism (1) that has a holding shaft (11) with a leading end formed in a shape complementary to the head (8a) of an external thread (8) so that when engaged with the head of the external thread, the positional relation with the external thread about the axis of the external thread is fixed, and a holding shaft drive unit (13) rotatively driving the holding shaft about the axis of the holding shaft; a robot body (2) that holds and moves the screw-driving mechanism; and a robot controller (3) that controls the robot body and controls the holding shaft drive unit as an external shaft which performs work in cooperation with the robot body.

Description

Robot system

The present invention relates to a robot system.

2. Description of the Related Art Conventionally, an apparatus for fastening a screw by a robot is known (for example, see Patent Document 1).

This device is connected to the robot main body, the nut runner controlled by the nut runner control section, the robot main body and the nut runner control section, and outputs a command signal to the robot main body and the nut runner control section. A robot control unit for controlling the nut runner via the. As a result, the screw can be automatically tightened.

JP 2002-331428 A

On the other hand, in recent years, it has been demanded that the screw tightening by the robot be performed more rapidly and finely. However, the conventional apparatus has a problem that it is difficult to perform the cooperation between the nut runner and the robot at high speed and finely.

In order to solve the above-described problem, a robot system according to an aspect of the present invention is configured such that a tip is formed in a shape complementary to a head of a male screw, and the male screw is engaged with the head of the male screw. A screw turning mechanism having a holding shaft in which a positional relationship around the axis of the male screw is fixed, and a holding shaft drive unit that drives the holding shaft to rotate about the axis of the holding shaft, and the screw turning mechanism A robot main body that holds and moves the screw turning mechanism; and a robot controller that controls the robot main body and controls the holding shaft driving unit as an external shaft that performs work in cooperation with the robot main body.

According to this configuration, since the robot controller that controls the robot body also controls the holding axis drive unit, communication according to a predetermined protocol for communication between the two controllers as in the prior art becomes unnecessary. And the delay in the cooperative operation between the screw turning mechanism and the screw turning mechanism can be reduced. Therefore, the screw turning operation can be performed at high speed and finely.

Also, the configuration of the screw turning mechanism can be simplified, which is advantageous for manufacturing and low in manufacturing cost.

The robot body may be an articulated robot.

According to this configuration, the screw tightening robot can be controlled during the control of the articulated robot.

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 the holding shaft driving portion controls the holding shaft. The screw turning mechanism may be controlled so as to stop the rotational driving of the holding shaft based on the determination as to whether or not the current for rotational driving has reached the limit current corresponding to the target torque.

According to this configuration, since the tightening torque of the screw is detected using the drive current of the holding shaft drive unit as the external shaft of the robot controller, the screw tightening can be performed finely and a dedicated torque sensor is not required. Become.

The robot controller further includes an engaging portion that engages with the holding shaft and detects a load torque of the engaging portion, and the robot controller moves the holding shaft to move the holding shaft. The holding shaft and the engaging portion are engaged, and control is performed so that a predetermined current is supplied to the holding shaft driving portion, and the current and the load torque detected by the torque sensor are associated to create the table. The limit current may be calculated based on the table.

According to this configuration, the deviation between the target tightening torque of the screw and the actual tightening torque can be automatically prevented.

The robot controller, when screwing the male screw into the female screw after screwing the male screw and the female screw hole corresponding to the male screw, from the screwing operation start position of the male screw. While the male screw is positioned at the reference position between the screwing operation start position and the screwing operation end position, the rotation speed is higher than the rotation speed from the reference position to the screwing operation end position. The holding shaft driving unit may be controlled.

According to this configuration, the screw can be fastened quickly.

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 driving unit by a predetermined distance in an axial direction of the holding shaft. And an urging portion that urges in the direction from the tip to the tip, and a position detection portion that detects a relative position of the holding shaft with respect to the holding shaft driving portion in the axial direction of the holding shaft. .

According to this configuration, since the screw tightening can be performed while the holding shaft driving unit is positioned at a predetermined position during the screw tightening, the control by the robot controller can be simplified.

In order to solve the above problems, a control method of a robot system according to an aspect of the present invention is such that a tip is formed in a shape complementary to a head of a male screw and is engaged with the head of the male screw. A screw turning mechanism comprising: a holding shaft in which a positional relationship around the axis of the male screw relative to the male screw is fixed; and a holding shaft driving unit that rotationally drives the holding shaft about the axis of the holding shaft; and the screw A robot body that holds a turning mechanism and moves the screw turning mechanism; a robot controller that controls the robot body and controls the holding shaft drive unit as an external shaft that performs work in cooperation with the robot body; The robot controller controls at least one of a position and a rotation speed at a rotation angle position of the holding shaft when performing a tightening operation of the male screw engaged with the holding portion; and The screw turning mechanism to stop the rotation driving of the holding shaft based on the determination as to whether or not the current for driving the holding shaft to rotate the holding shaft has reached the limit current corresponding to the target torque. Is configured to control.

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

The robot controller, when screwing the male screw into the female screw after screwing the male screw and the female screw hole corresponding to the male screw, from the screwing operation start position of the male screw. While the male screw is located at the reference position between the screwing operation start position and the screwing operation end position, the speed is higher than the rotational speed from the reference position to the screwing operation end position. The holding shaft driving unit may be controlled.

According to this configuration, the screw can be fastened quickly.

The present invention has an effect that the screw turning operation can be performed at high speed and finely.

It is a figure which shows roughly the structural example of the robot system which concerns on Embodiment 1 of this invention. It is principal part sectional drawing which shows the structural example of the screwing mechanism of the robot system of FIG. FIG. 2 is a block diagram schematically showing a configuration example of a robot controller of the robot system of FIG. 1. It is a flowchart which shows the operation example of the robot system of FIG. It is a flowchart which shows the operation example of the robot system of FIG. It is a flowchart which shows the operation example of the robot system of FIG. It is a flowchart which shows the operation example of the robot system of FIG. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of screw removal operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of screw removal operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of screw removal operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of temporary fastening operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of temporary fastening operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of temporary fastening operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of temporary fastening operation | movement. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of this fastening operation | movement. FIG. It is a figure which shows the operation example of the robot system of FIG. 1, and is a figure which shows the operation example of this fastening operation | movement. 1 shows changes in the current value output to the holding shaft drive unit detected by the current detection unit of the servo amplifier and changes in the position of the holding shaft detected by the holding shaft position detection unit in the operation example of the robot system of FIG. It is a graph and is a graph which shows the change in temporary fastening operation. 1 shows changes in the current value output to the holding shaft drive unit detected by the current detection unit of the servo amplifier and changes in the position of the holding shaft detected by the holding shaft position detection unit in the operation example of the robot system of FIG. It is a graph and is a graph which shows the change in this fastening operation | movement. It is a figure which shows roughly the structural example of the control method of the robot system which concerns on Embodiment 2 of this invention. It is a block diagram which shows roughly the structural example of the robot controller of the control method of the robot system of FIG. It is a figure which shows the limiting current calculation table of the control method of the robot system of FIG.

(Focus point of the present invention)
The present inventors have intensively studied to perform screw tightening by a robot at high speed and finely. The conventional technology has been observed to have the following drawbacks.

The screw tightening operation generally includes temporary tightening and final tightening, rotation speed adjustment when the screw is screwed into the screw hole, tightening torque management, and the like. Specifically, when two articles are fastened using a plurality of screws, the plurality of screws are temporarily tightened and then finally tightened in order to uniformly disperse the tightening force. In this case, the nut runner is screwed while moving the nut runner sequentially to a plurality of screw tightening locations by the robot.To that end, the robot notifies the nut runner that the screw tightening location has been reached each time the screw is tightened, and The nut runner needs to notify the robot that the screw tightening operation has been completed. Further, when the screw is screwed into the screw hole, the screw is screwed into the screw hole at a low rotational speed in order to ensure that the axial center of the screw and the central axis of the screw hole coincide with each other. Tighten the screw by increasing the rotation speed to. In this case, the screw advances as the screw tightening proceeds. If the nut runner is moved by a robot in order to follow the advance of the screw, the socket, which is the transmission part of the rotational force to the screw in the nut runner, information on the advance of the screw (rotation speed, screw) The nut runner must provide the robot with the real-time position of the robot in real time. In order to ensure the quality of screw tightening, the tightening torque is managed. In this case, 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 attached to the robot and the screw fastening 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 exchange of commands and data between the two controllers is performed by communication according to a predetermined protocol. Therefore, since it takes time to exchange commands and data between the two controllers, it is difficult to coordinate the nut runner and the robot at high speed and finely.

In order to overcome the disadvantages of the prior art, the present inventors have formed a tip having a shape complementary to the head of the male screw and engaged with the head of the male screw. A screw turning mechanism having a holding shaft in which a positional relationship around the axis of the male screw is fixed, and a holding shaft drive unit that drives the holding shaft to rotate about the axis of the holding shaft, and the screw turning mechanism A robot main body that holds and moves the screw turning mechanism; and a robot controller that controls the robot main body and controls the holding shaft driving unit as an external shaft that performs work in cooperation with the robot main body. He came up with the invention of the robot system.

According to the present invention, since the robot controller that controls the robot body also controls the holding shaft drive unit, communication according to a predetermined protocol for communication between the two controllers as in the prior art becomes unnecessary. And the delay in the cooperative operation between the screw turning mechanism and the screw turning mechanism can be reduced. Therefore, the screw turning operation can be performed at high speed and finely. Further, the configuration of the screw turning mechanism can be simplified, which is advantageous for manufacturing and low in manufacturing cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.

(Embodiment 1)
FIG. 1 is a diagram schematically showing a configuration example of a robot system 100 according to the first embodiment of the present invention.

The robot system 100 can be used for screw tightening work.

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, an articulated industrial robot (articulated robot). The robot body 2 includes a base 21, an articulated arm 22, and an arm driving unit 23 (see FIG. 3).

The base 21 is a table installed on a mounting surface such as a floor surface and supports the arm 22.

The arm 22 includes, for example, a plurality of joints, and a base end portion is rotatably connected to the base portion 21.

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

[Screw turning mechanism]
FIG. 2 is a cross-sectional view of an essential part showing a configuration example of the screw turning mechanism 1 of the robot system 100.

As shown in 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 includes a shaft support portion 12, a holding shaft position detection portion 14, and a support frame 15.

The holding shaft 11 has an engaging portion 11a that engages with the head 8a of the male screw 8 at the tip. The engaging portion 11a is formed in a substantially regular hexagonal convex shape, for example, when viewed from the extending direction of the axis L1 of the holding shaft 11. Further, when viewed from the axial direction of the male screw 8, a substantially regular hexagonal groove is formed in the head 8a of the male screw 8, and is formed in a shape complementary to the engaging portion 11a. That is, the engaging portion 11a and the head portion 8a of the male screw 8 can be engaged with each other by matching the axis and the angular position (phase) around the axis L1. Then, by engaging the engaging portion 11a with the head 8a of the male screw 8, the relative positional relationship around the axis of the male screw 8 with respect to the male screw 8 is fixed. Usually, a plurality of holding shafts 11 are prepared according to the type of 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.

Also, the holding shaft 11 has a connecting portion 11b configured to be detachable from a distal end portion of a shaft support portion 12 described later at a proximal end portion.

Further, the holding shaft 11 is a magnet and is configured to be able to draw the male screw 8 made of a magnetic material. Therefore, the male screw 8 can be locked to the holding shaft 11 by engaging the engaging portion 11 a with the head 8 a of the male screw 8.

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

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

The movable shaft 32 is formed in a rod shape extending in the extending direction of the axis L1. The movable shaft 32 has a connection portion 32a at the tip. The connecting portion 32a is configured to be detachable from the connecting portion 11b of the holding shaft 11, so that the holding shaft 11 can be replaced with a shape corresponding to the type of male screw 8 used by the shape of the engaging portion 11a. It has become.

Further, the connecting portion 32a of the movable shaft 32 and the engaging portion 11a of the holding shaft 11 are attached with the connecting portion 11b of the holding shaft 11 to the connecting portion 32a of the movable shaft 32, so that at least relative to the axis L1. The positional relationship is fixed. Therefore, when the movable shaft 32 is rotated, the holding shaft 11 is also rotated at the same time.

Further, the movable shaft 32 has an engaging recess 32b at the base end. The engagement recess 32b is configured to be fitted to the distal end portion of the fixed shaft 31 as viewed from the extending direction of the axis L1 and to be slid with respect to the fixed shaft 31 in the extending direction of the axis L1. Yes. As a result, the holding shaft 11 is moved in the direction from the first position P1 to the base end of the holding shaft 11 on the axis L1 from the first position P1, and the second position P2 close to the base end of the fixed shaft 31. It is configured to be able to move between. In other words, the holding shaft 11 is configured to be able to receive a rotational force with respect to the holding shaft driving unit 13 and to be movable relative to the distance D1 in the axial direction of the holding shaft 11.

The engaging recess 32b of the movable shaft 32 is formed in a shape complementary to the distal end portion of the fixed shaft 31 when viewed from the extending direction of the axis L1, and the movable shaft 32 and the fixed shaft 31 are formed around the axis L1. The relative positional relationship is fixed. Specifically, the engaging recess 32b and the distal end of the fixed shaft 31 have a non-circular cross section (for example, a polygon, a circle having irregularities on the outer periphery, etc.) that fits with a minute gap therebetween. It is formed. Therefore, when the fixed shaft 31 is rotated, the movable shaft 32 and the holding shaft 11 are configured to 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 outside the fixed shaft 31 and between the proximal end portion of the fixed shaft 31 and the proximal end portion of the movable shaft 32. The portions are in contact with the base end of the fixed shaft 31 and the base end of the movable shaft 32, respectively. Accordingly, the spring 33 biases the base end portion of the fixed shaft 31 and the base end portion of the movable shaft 32 so as to be separated from each other. Accordingly, in a normal state, the movable shaft 32 is configured to be positioned at the first position P1, and the biasing force of the spring 33 is pressed by pressing the holding shaft 11 from the first position P1 toward the second position P2. Against this, the holding shaft 11 is configured to move from the first position P1 toward the second position P2.

Note that the spring 33 is not limited to a compression coil spring. For example, the movable shaft 32 is configured to be positioned at the first position P1 in a normal state using a tension coil spring, and the holding shaft 11 is pressed from the first position P1 toward the second position P2. Accordingly, the holding shaft 11 may be configured to move from the first position P1 toward the second position P2 against the urging force of the spring 33. The spring 33 is not limited to a coil spring, and may be a gas spring.

In the first position P1, the movable shaft 32 located at the first position P1 contacts the guide portion 15a of the support frame 15 or a portion in the vicinity thereof, and moves from the second position P2 to the first position P1 in the direction of the axis L1. It is prescribed by being regulated not to move to the side.

The holding shaft driving unit 13 rotationally drives the holding shaft 11 around the axis L1 via the shaft support unit 12. The holding shaft driving unit 13 is, for example, a servo motor. The drive shaft 13 a of the holding shaft drive unit 13 is fixedly connected to the base end portion of the fixed shaft 31. Therefore, the holding shaft drive unit 13 rotates the fixed shaft 31, the movable shaft 32, and the holding shaft 11 by the driving force, thereby performing the screw fastening operation of the male screw 8 that engages with the holding shaft 11. It is configured to be able to. The drive shaft 13a includes an encoder 13e (see FIG. 3) that detects an angular position and a rotation speed of the drive shaft 13a.

The support frame 15 is configured in a cylindrical shape, for example, and is fitted on the outside of the fixed shaft 31 and the movable shaft 32. The base end portion of the support frame 15 supports the holding shaft driving unit 13. As described above, since the drive shaft 13a of the holding shaft drive unit 13 and the fixed shaft 31 are fixed, the relative positional relationship in the extending direction of the axis L1 between the support frame 15 and the fixed shaft 31 is fixed. Yes.

The holding shaft position detector 14 detects a relative position of the holding shaft 11 with respect to the shaft support 12 in the extending direction of the axis L1.

Further, the guide portion 15 a is provided so as to be interposed between the tip end portion of the support frame 15 and the movable shaft 32. The guide portion 15a guides the movable shaft 32 so as to be movable in the axial direction of the axis L1 with respect to the support frame 15, and guides it so as to be rotatable around the axis L1.

The holding shaft position detector 14 includes, for example, a sensor main body 41 that is a laser displacement meter, a reflector 42, and a reflector support 43.

The sensor main body 41 is disposed on an axis L2 extending in parallel with the axis L1, irradiates the reflecting plate 42 with laser light, and detects the distance from the reflecting plate 42 by the reflected light from the reflecting plate 42. It is configured to be able to. The sensor body 41 is attached to the support frame 15. Therefore, the sensor body 41 has a fixed relative positional relationship in the extending direction of the axis L1 with respect to the fixed shaft 31.

The reflection plate 42 is disposed on the axis L2 and is attached to the support frame 15 via the reflection plate support portion 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 in parallel with the axis L1, and a reflection plate 42 is attached to the base end portion. The support shaft connecting portion 43b is attached to the movable shaft 32 via a bearing. Therefore, the support shaft connecting portion 43b is configured to rotate relative to the movable shaft 32 around the axis L1. On the other hand, the support shaft connecting portion 43b is fixed and attached to the movable shaft 32 so as not to move in the extending direction of the axis L1. And the front-end | tip of the support shaft 43a is attached to the support shaft connection part 43b. The support shaft guide portion 43 c is fixed to the support frame 15. The support shaft guide 43c has an insertion hole coaxial with the axis L2, and the support shaft 43a is inserted through the insertion hole. 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 43c restricts the support shaft 43a from moving on a plane orthogonal to the extending direction of the axis L2.

Therefore, as described above, the support shaft connecting portion 43b is fixed and attached to the movable shaft 32 so as not to move in the extending direction of the axis L1, and the support shaft guide portion 43c further attaches the support shaft 43a to the axis L2. Since the holding shaft 11 and the movable shaft 32 are moved relative to the support frame 15 in the extending direction of the axis L1, the support shaft 11 and the movable shaft 32 are supported together. The shaft connecting portion 43b, the support shaft 43a, and the reflection plate 42 move relative to the support frame 15 in the extending direction of the axis L1. On the other hand, since the sensor body 41 is attached to the support frame 15 as described above, it does not move with the movement of the holding shaft 11 and the movable shaft 32. Therefore, the distance between the sensor main body 41 and the reflecting 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 shaft position detection unit 14 is configured to detect the relative position of the holding shaft 11 with respect to the holding shaft driving unit 13 in the extending direction of the axis L1.

Further, as described above, the support shaft connecting portion 43b is configured to rotate relative to the movable shaft 32 around the axis L1, and the support shaft guide portion 43c further includes the support shaft 43a extending in the extending direction of the axis L2. Since it is restricted so that it does not move on the orthogonal plane, the reflector 42 and the reflector support part 43 are configured not to rotate with the movable shaft 32 even if the movable shaft 32 rotates around the axis L1. Therefore, the reflecting plate 42 does not come off from the axis L2.

[Robot controller]
FIG. 3 is a block diagram schematically showing the configuration of the robot controller 3. Hereinafter, the control system of the robot system 100 will be described with reference to FIG.

The robot controller 3 is arranged around the robot body 2 and performs position control, speed control, or current control of joint axes of the robot body 2 and control target axes other than the robot body 2. The control target axis other than the robot body 2 constitutes an external axis of the robot controller 3. In this embodiment, the robot controller 3 controls the drive shaft 13a of the holding shaft drive unit 13 as an external shaft. Therefore, the robot controller 3 is configured to be able to control the drive shaft 13 a of the holding shaft drive unit 13 of the screw turning mechanism 1 so as to control the joint axis of the robot body 2. That is, from the viewpoint of a person operating the robot body 2, the screw turning mechanism 1 can be controlled using an operation command similar to the operation command for the robot body 2, and the screw tightening robot is controlled in the control of the articulated 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 based on a unique operation command. Therefore, it is advantageous for manufacturing and the manufacturing cost is low. Hereinafter, the configuration of the robot controller 3 will be described in detail.

The robot controller 3 includes, for example, a control unit 51 having a computing unit such as a CPU, a storage unit 54 having a memory such as a ROM and a RAM, and a servo amplifier 52 corresponding to the arm driving unit 23 and the holding shaft driving unit 13. I have.

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 shaft driving unit 13 via the servo amplifier. The control unit 51 may be configured by a single controller that performs centralized control, or may be configured by a plurality of controllers that perform distributed control in cooperation with each other.

The servo amplifier 52 performs servo control of the arm drive unit 23 and the holding shaft drive unit 13 which are servo motors. That is, the servo amplifier 52 performs follow-up control so that the deviation from the current value with respect to the target angular position, target rotational speed, or target torque determined by the control unit 51 is zero. The servo amplifier 52 includes a current detection unit (not shown) that detects a current value output to the arm drive unit 23 and the holding shaft drive unit 13.

The rotational angle position information and rotational speed information output from the encoder 23e (see FIG. 3) of the arm drive unit 23 and the encoder 13e of the holding shaft drive unit 13, and the position of the holding shaft 11 output from the holding shaft position detection unit 14. Information is input to the control unit 51. The current value information of the current output from the servo amplifier 52 detected by the current detection unit of the servo amplifier 52 to the arm driving unit 23 and the holding shaft driving unit 13 is also input to the control unit 51.

A predetermined control program is stored in the storage unit 54, and when the control unit reads and executes these control programs, the operations of the screw turning mechanism 1 and the robot body 2 are controlled. Further, the storage unit 54 has a limit current calculation table indicating the relationship between the current value output from the servo amplifier 52 to the holding shaft driving unit 13 and the tightening torque of the holding shaft driving unit 13 corresponding to the current value. T is memorized.

Further, in the storage unit 54, a screw removing approach position Pa, a screw removing position Pb, a screw removing retracting position Pc, a temporary fastening approach position Pf, a temporary fastening approach position Pg, a final fastening approach position Ps, which will be described later, of the screw turning mechanism 1. The final fastening position Pt is stored. The storage unit 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.

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

First, as shown in FIG. 4A, the control unit 51 performs a screw removing operation for moving the screw turning mechanism 1 and holding the male screw 8 set (held) on the screw mounting table 110 on the holding shaft 11 (step S1). ). For example, the male screw 8 is inserted into the insertion hole 110a of the screw mounting table 110 (see FIG. 6A) and held by the screw mounting table 110. The insertion hole 110a is formed to have a diameter slightly larger than the diameter of the screw shaft of the male screw 8, and is configured so that the male screw 8 can be easily pulled out.

Then, when the male screw 8 is held on the holding shaft 11, the male screw 8 is then carried to a position where the female screw hole 9 to be screwed with the male screw 8 is provided, and the male screw 8 and the female screw hole 9 are moved. Are temporarily tightened and screwed (step S2).

Next, a final tightening operation for tightening the male screw 8 with a predetermined tightening torque is performed (step S3). In addition, you may move the screwing mechanism 1 to arbitrary retreat positions after that. Hereinafter, the details of the screw removing operation, the temporary fastening operation, and the final fastening operation will be described.

<Screw removal operation>
FIG. 4B is a flowchart illustrating an example of the operation of the robot system 100 and describes the screw removal operation.

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

First, as shown in FIG. 5A, the control unit 51 controls the robot 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 engaging portion 11a of the holding shaft 11 faces the head 8a of the male screw 8 held by the screw mounting base 110, and the axis of the male screw 8 and the axis of the holding shaft 11 This is the position where L1 matches.

Next, as shown in FIG. 5B, the control unit 51 controls the robot body 2 to move the screw turning mechanism 1 along the axis L1, and position the screw turning mechanism 1 at the screw removal position Pb (step S12). ). The screw removal position Pb is set on the side (the side from the base end of the holding shaft 11 toward the tip) that brings the holding shaft 11 closer to the male screw 8 in the extending direction of the axis L1 of the screw taking approach position Pa. If the angular positions around the axis L1 of the engaging portion 11a of the eleventh and the head 8a of the male screw 8 coincide, the holding shaft 11 is moved from the first position P1 to the second position against the urging force of the spring 33. It is a position that engages with the male screw 8 in a state where it is located at the third position P3 that is slightly pushed in the direction toward P2.

When the male screw 8 is set on the screw mounting base 110, the angular position around the axis of the male screw 8 is normally set at random, so that the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 are set. There is a possibility that the angular positions around the axis line L1 of the two do not match. In this case, as shown in FIG. 5C, the engaging portion 11 a of the holding shaft 11 of the screw turning mechanism 1 located at the screw removing position Pb does not fit into the groove of the head 8 a of the male screw 8, and does not fit into the head 8 a. It rides and is pushed further in the direction from the first position P1 to the second position P2 than the third position P3.

Next, the control unit 51 determines whether or not the holding shaft 11 is located at the third position P3 based on the position information of the holding shaft 11 output from the holding shaft position detection unit 14 (step S13). As described above, if the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 are engaged, the holding shaft 11 is located at the third position P3. On the other hand, if the holding shaft 11 and the male screw 8 are not engaged, the holding shaft 11 is pushed further in the direction from the first position P1 to the second position P2 than the third position P3 by the distance d1. Therefore, by performing the determination, it can be determined whether the engaging portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 are engaged.

If the control unit 51 determines that the holding shaft 11 is not located at the third position P3 (No in step S13), the control unit 51 then rotates the holding shaft 11 (step S14). At this time, when the angular positions around the axis L1 of the engaging portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 coincide, the engaging portion 11a of the holding shaft 11 is moved by the urging force of the spring 33. Pushed into the groove of the head 8a, the engaging portion 11a of the holding shaft 11 and the head 8a of the male screw 8 engage. Then, it is determined again whether or not the holding shaft 11 is positioned 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 portion 8a of the male screw 8 coincide. Thereby, the holding shaft 11 and the male screw 8 can be engaged. When the holding shaft 11 and the male screw 8 are engaged, the holding shaft 11 that is a magnet pulls the male screw 8 made of a magnetic material, and 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 positions the screw turning mechanism 1 at the screw removal / retraction position Pc (step S13). S15). As a result, the male screw 8 is pulled out of the screw mounting table 110. Then, the screw removing operation is finished.

<Temporary tightening operation>
FIG. 4C is a flowchart illustrating an operation example of the robot system 100, and describes the temporary fastening operation.

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

FIG. 8 shows changes in the current value output to the holding shaft drive unit 13 detected by the current detection unit of the servo amplifier 52 and the holding shaft 11 detected by the holding shaft position detection unit 14 in the operation example of the robot system 100. It is a graph which shows the change of the position of, and is a graph which shows the change in temporary fastening operation | movement.

First, as shown in FIG. 6A, the control unit 51 controls the robot body 2 to position the screw turning mechanism 1 that holds the male screw 8 on the holding shaft 11 at the temporary fastening approach position Pf (step S21). . The temporary fastening approach position Pf is set at a position where the tip of the male screw 8 held by the holding shaft 11 faces the end of the female screw hole 9, and the axis of the female screw hole 9 to which the male screw 8 is screwed is held. This is the position where the axis L1 of the shaft 11 coincides.

Next, as shown in FIG. 6B, the control unit 51 controls the robot body 2 to move the screw turning mechanism 1 along the axis L1, and to position the screw turning mechanism 1 at the temporary fastening position Pg (step S22). ). The temporary fastening position Pg is set on the side where the male screw 8 approaches the female screw hole 9 in the extending direction of the axis L1 of the temporary fastening approach position Pf (the side from the proximal end to the distal end of the holding shaft 11), and is further held. This is the position where the tip of the male screw 8 held on the shaft 11 and the end of the female screw hole 9 abut. In this state, the temporary fastening position Pg is configured so that the holding shaft 11 is located at a position where the holding shaft 11 is largely pushed in the direction from the first position P1 toward the second position P2 against the urging force of the spring 33. This position is preferably configured such that the distance from the first position P1 is longer than the length of the threaded portion of the screw shaft of the male screw 8. Then, the control unit 51 stores the position in the axis L1 direction of the holding shaft 11 input from the holding shaft position detection unit 14 in the storage unit 54 as the fourth position P4.

Next, the control unit 51 drives the holding shaft driving unit 13 to rotate the holding shaft 11 at a low speed in the tightening 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 screwed together. 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.

Then, when the angular position around the axis L1 of the tip of the screw thread of the male screw 8 and the tip of the screw groove of the female screw hole 9 coincides, and the male screw 8 and the female screw hole 9 are screwed together (this applies), The screw 8 is screwed into the female screw hole 9. As a result, the difference between the position of the holding shaft 11 input from the holding shaft position detector 14 and the fourth position P4 increases.

Next, the control unit 51 moves the holding shaft 11 until it determines that the difference (displacement) between the position of the holding shaft 11 input from the holding shaft position detection unit 14 and the fourth position P4 is larger than a predetermined value. The male screw 8 is rotated at a low speed in the tightening direction (step S24). The predetermined value is preferably set to a value corresponding to the thread depth when the male screw 8 and the female screw hole 9 are securely engaged. For example, the predetermined value is 1 of the screw pitch of the male screw 8. The value is / 2.

As described above, the holding shaft 11 is urged from the second position P2 to the first position P1 by the spring 33. Therefore, when the male screw 8 sinks into the female screw hole 9, the holding shaft 11 follows this. The holding shaft 11 is configured to move from the second position P2 toward the first position P1. Therefore, the engagement state between the engagement portion 11a of the holding shaft 11 and the head portion 8a of the male screw 8 is maintained even when the female screw hole 9 is separated from the screw rotation mechanism 1. Therefore, it is possible to perform screw tightening while the screw turning mechanism 1 is positioned at a predetermined position. Therefore, the control content by the robot controller 3 can be simplified. The position (rotational angle position) of the male screw 8 when the male screw 8 and the female screw hole 9 are screwed together constitutes a screwing operation start position.

Next, when the male screw 8 is engaged with the female screw hole 9, the control unit 51 rotates the holding shaft 11 in the tightening direction of the male screw 8 at a speed V1 (see FIG. 8) (step S25). 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, as shown in FIG. 6C, the control unit 51 rotates the holding shaft 11 at the speed V1 until the holding shaft 11 is located at the fifth position P5 (step S26). The position of the holding shaft 11 at the fifth position P5 is detected based on, for example, the rotational angle position of the holding shaft 11 or the position of the holding shaft 11 in the direction of the axis L1 input from the holding shaft position detector 14. .

And if the control part 51 determines with the holding | maintenance axis | shaft 11 having been located in the 5th position P5, it will next rotate the holding | maintenance axis | shaft 11 at the speed V2 in the tightening direction of the head 8a (step S27). The speed V2 is a speed 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 holding shaft 11 is located at the fifth position P5 constitutes the reference position.

As described above, the control unit 51 engages the male screw 8 with the female screw hole 9 and then inserts the male screw 8 into the female screw hole 9 from the position where the male screw 8 is inserted. While the male screw is located between the reference position and the reference position, the rotation speed is higher than the rotation speed from the reference position to the screwing operation end position. Thereby, the male screw 8 and the female screw hole 9 can be quickly screwed together.

Next, the control unit 51 determines whether or not the current value Ir has reached the temporary fastening current threshold value Ia (step S28). This determination is to determine whether the seating surface of the head 8a of the male screw 8 is seated as shown in FIG. 6D. That is, as shown in FIG. 8, when the seating surface of the head 8a of the male screw 8 is seated, the rotational speed of the male screw 8 is rapidly reduced or the rotation of the male screw 8 is stopped. Therefore, the difference between the target rotation angle position or target rotation speed and the current value is suddenly increased, and the servo amplifier 52 that controls the holding shaft drive unit 13 by position control or speed control is able to obtain The current supplied to the holding shaft driving unit 13 is rapidly increased so as to reduce the deviation from the current value. Therefore, the control unit 51 compares this value with the current value Ir using the current threshold value Ia set to a value that can capture the rapidly increasing current value, and the current value Ir is determined as the temporary fastening current. By determining whether or not the threshold value Ia has been reached, it can be determined whether or not the seating surface of the head 8a of the male screw 8 has been seated. The temporary fastening current threshold value Ia is set to be smaller than a final fastening current threshold value Ib described later. Accordingly, it is possible to prevent the male screw 8 from being tightened with an excessive torque, and the male screw 8 or the female screw hole 9 from being damaged.

Further, as described above, since the speed V2 is configured to be lower than the speed V1, the period from when the seating surface of the head 8a of the male screw 8 is seated to when the temporary fastening operation is finished. Therefore, it is possible to prevent the male screw 8 from being tightened by excessive torque and the male screw 8 or the female screw hole 9 from being damaged.

Then, while determining that the current value Ir has not reached the final fastening current threshold Ib (limit current) (No in step S28), the control unit 51 rotates the holding shaft 11 (step S27), and the current value When Ir reaches the final fastening current threshold value Ib (limit current) (Yes in step S28), the rotation of the holding shaft 11 is stopped (step S29). The position (rotational angle position) of the male screw 8 when the rotation of the holding shaft 11 is stopped constitutes the screwing operation end position.

Therefore, when the male screw 8 is screwed into the female screw hole 9 after the male screw 8 and the female screw hole 9 are screwed together, the control unit 51 is screwed in from the screwing operation start position of the male screw 8. While the male screw 8 is located at the reference position between the start position and the screwing operation end position, the holding shaft drive is performed so that the rotation speed is higher than the rotation speed from the reference position to the screwing operation end position. It is comprised so that a part may be controlled.

Then, the temporary fastening operation is finished.

<Tightening action>
FIG. 4D is a flowchart illustrating an operation example of the robot system 100 and describes the final fastening operation.

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

FIG. 9 shows changes in the current value output to the holding shaft drive unit 13 detected by the current detection unit of the servo amplifier 52 and the holding shaft 11 detected by the holding shaft position detection unit 14 in the operation example of the robot system 100. It is a graph which shows the change of this position, and is a graph which shows the change in this fastening operation | movement.

First, as shown in FIG. 7A, the control unit 51 controls the robot body 2 to position the screw turning mechanism 1 at the final fastening approach position Ps (step S31). The final fastening approach position Ps is a position where the engaging portion 11a of the holding shaft 11 faces the head 8a of the male screw 8 that is screwed into the female screw hole 9, and the axis of the male screw 8 and the axis of the holding shaft 11 This is the position where L1 matches.

Next, as shown in FIG. 7B, the control unit 51 controls the robot body 2 to move the screw turning mechanism 1 along the axis L1, and to position the screw turning mechanism 1 at the final fastening position Pt (step S32). ). The final tightening position Pt is set on the side where the holding shaft 11 approaches the male screw 8 in the extending direction of the axis L1 of the final tightening approach position Ps (the side from the proximal end to the distal end of the holding shaft 11). If the angular positions around the axis L1 of the engaging portion 11a of the eleventh and the head 8a of the male screw 8 coincide, the holding shaft 11 is moved from the first position P1 to the second position against the urging force of the spring 33. It is a position that engages with the male screw 8 in a state of being in the sixth position P6 pushed in the direction toward P2.

Next, the control unit 51 executes Steps S33 to S34 to engage the holding shaft 11 and the male screw 8. The operation is the same as Steps S13 to S14, and the description thereof is omitted. .

When the final fastening operation is performed with the holding shaft 11 and the male screw 8 engaged after the temporary fastening operation is completed, the above operation can be omitted.

Next, the control unit 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 or not the current value Ir has reached the final fastening current threshold Ib (limit current) and the holding shaft 11 has not been rotated (step S36). That is, the control unit 51 performs a determination including a determination as to whether or not the current required for the holding shaft driving unit 13 to rotationally drive the holding shaft 11 has reached the final fastening current threshold value Ib.

As shown in FIG. 9, the final fastening current threshold value Ib is a value determined based on a current value corresponding to a predetermined tightening torque of the male screw 8. It is. In the present embodiment, the final tightening current threshold value Ib refers to the current corresponding to the tightening torque of the male screw 8 defined in advance by referring to the limit current calculation table T stored in the storage unit 54 by the control unit 51. It is calculated by calculating. Therefore, the control unit 51 compares the final fastening current threshold value Ib with the current value Ir, and determines whether or not the current value Ir has reached the final fastening current threshold value Ib. It can be determined whether or not the male screw 8 is tightened. Further, in the present embodiment, the control unit 51 also determines whether or not the holding shaft 11 is rotating, so that the male screw 8 is tightened with a predetermined tightening torque more reliably. It can be determined whether or not.

Since the robot system 100 detects the tightening torque of the male screw 8 using the drive current of the holding shaft driving unit 13 as the external shaft of the robot controller 3, the screw tightening can be performed finely and a dedicated screw can be used. A torque sensor is unnecessary.

The control unit 51 can tighten the male screw 8 more accurately by simultaneously determining whether or not the displacement of the holding shaft 11 is not detected, for example, in addition to the above determination.

Then, the controller 51 determines that the holding shaft 11 does not reach the final fastening current threshold value Ib (limit current) or the current value Ir has reached the final fastening current threshold value Ib (limit current). While it is determined that it is rotating (No in step S36), the holding shaft 11 is rotated (step S35), the current value Ir reaches the final fastening current threshold Ib (limit current), and the holding shaft 11 rotates. If it determines with having not carried out (in step S36 Yes), rotation of the holding shaft 11 will be stopped (step S37). The rotation of the holding shaft 11 is stopped by, for example, setting the target rotation speed to zero. In addition, it is not restricted to this, The control part 51 controls the brake device for stopping rotation of the holding shaft 11, and stops the rotation of the holding shaft 11 by applying a brake to the holding shaft 11. Also good.

And the control part 51 complete | finishes control of the holding shaft 11, and complete | finishes this fastening operation | movement.

It should be noted that the control unit 51 may rotate the holding shaft 11 in the loosening direction before finishing the final tightening operation. Thereby, the engaging portion 11a of the holding shaft 11 can be easily pulled out from the groove of the head 8a of the male screw 8.

As described above, in the robot system 100 according to the present invention, the robot controller 3 that controls the robot body 2 also controls the holding shaft drive unit 13. Communication according to a predetermined protocol becomes unnecessary, and the delay in the cooperative operation between the robot body 2 and the screw turning mechanism 1 can be reduced. Therefore, the screw turning operation can be performed at high speed and finely.

Also, the configuration of the screw turning mechanism 1 can be simplified, which is advantageous for manufacturing and low in manufacturing cost.

(Embodiment 2)
FIG. 10 is a diagram schematically showing a configuration example of the robot system 200 according to the second embodiment of the present invention. FIG. 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 body 2, a robot controller 3, and a torque sensor 204. The configurations of the screw turning mechanism 1, the robot main body 2, and the robot controller 3 are the same as those in the first embodiment, and a description thereof will be omitted.

The torque sensor 204 has an engaging portion 205 that engages with the holding shaft 11 of the screw turning mechanism 1. And the torque sensor 204 is comprised so that the load torque of the engaging part 205 may be detected. As shown in FIG. 11, the load torque value detected by the torque sensor 204 is input to the control unit 51.

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

First, the control unit 51 controls the robot body 2 to move the holding shaft 11 to engage the holding shaft 11 with the engaging unit 205.

Next, the control unit 51 determines a first current value to be supplied to the holding shaft driving unit 13 and controls the current to be supplied to the holding shaft driving unit 13 at the first current value. As a result, the holding shaft 11 rotates, the engaging portion 205 is tightened with a predetermined torque, and 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 repeatedly executed to obtain first to Nth current values which are different current values and load torque values respectively associated with these current values.

Then, an approximate expression is calculated based on the first to Nth current values and the load torque values associated with these current values, and this is determined as a limited current calculation table T as shown in FIG. To do.

As described above, the robot system 200 can automatically prevent a deviation between the target tightening torque of the screw and the actual tightening torque.

(Embodiment 3)
In the first embodiment, the screw turning mechanism 1 is configured such that the holding shaft 11 is urged by the spring 33 from the second position P2 toward the first position P1, and the male screw 8 is inserted into the female screw hole 9. When sinking, the holding shaft 11 is configured to move from the second position P2 toward the first position P1 following this. Instead, when the robot body 2 urges the holding shaft 11 from the second position P2 toward the first position P1, and the male screw 8 sinks into the female screw hole 9, the screw turning mechanism follows this. The control unit 51 may control the robot body 2 such that one holding shaft 11 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 turning mechanism 1 is detected based on the angle axis of the joint axis of the robot body 2. May be.

With this configuration, the screwing operation can be further performed at high speed and finely.

(Embodiment 4)
In the first embodiment, the holding shaft 11 is configured to be urged by the spring 33 from the second position P2 toward the first position P1. Instead, the holding shaft 11 may be configured to be biased from the second position P2 toward the first position P1 by a driving force of a driving unit such as a servo motor. Accordingly, the holding shaft 11 can be urged with an arbitrary urging force, so that the screw turning operation can be performed more finely.

(Embodiment 5)
In the first embodiment, the control unit 51 replaces the screw turning mechanism 1 and the robot main body 2 so that the holding shaft 11 attached to the movable shaft 32 is replaced with one having a shape corresponding to the type of the male screw 8. It may be configured to control.

From the above description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided 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 may be substantially changed without departing from the spirit of the invention.

Ia Temporary fastening current threshold value Ib Final fastening current threshold value Ir Current value L1 Axis line L2 Axis line P1 First position P2 Second position P3 Third position P4 Fourth position P5 Fifth position P6 Sixth position Pa Screw removal approach position Pb Screw removal position Pc Screw removal retracted position Pf Temporary fastening approach position Pg Temporary fastening position Ps Final fastening approach position Pt Final fastening position T Limit current calculation table 1 Screw turning mechanism 2 Robot body 3 Robot controller 8 Male screw 8a Head 9 Female screw hole 11 Holding Shaft

11a Engaging portion

11b Connection portion 12 Shaft support portion 13 Holding shaft driving portion 13a Driving shaft 13e Encoder 14 Holding shaft position detecting portion 15 Support frame 21 Base portion 22 Arm 23 Arm driving portion 23e Encoder 24 Arm driving portion 31 Fixed shaft 32 Movable Shaft

32a connecting portion

32b engaging recess 33 41 Sensor body 42 Reflector plate 43 Reflector plate support part 43a Support shaft 43b Support shaft connection part 43c Support shaft guide part 51 Control part 52 Servo amplifier 54 Storage part 100 Robot system 110 Screw mount 110a Insertion hole 200 Robot system 204 Torque sensor 205 Engagement Joint

Claims

A holding shaft, the tip of which is formed in a shape complementary to the head of the male screw and engaged with the head of the male screw, so that the positional relationship around the axis of the male screw with respect to the male screw is fixed; A screw turning mechanism having a holding shaft drive unit that rotationally drives the holding shaft around an axis of the holding shaft;
A robot body that holds the screw turning mechanism and moves the screw turning mechanism;
A robot system comprising: a robot controller that controls the robot body and controls the holding shaft drive unit as an external shaft that performs work in cooperation with the robot body.
The robot system according to claim 1, wherein the robot body is an articulated robot.
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 the holding shaft driving portion controls the holding shaft. The screw turning mechanism is controlled to stop the rotational driving of the holding shaft based on the determination whether or not the current for rotational driving has reached the limit current corresponding to the target torque. The robot system described.
An engagement portion connected to the robot controller and engaged with the holding shaft, further comprising a torque sensor for detecting a load torque of the engagement portion;
The robot controller moves the holding shaft to engage the holding shaft with the engaging portion, and controls so that a predetermined current is supplied to the holding shaft driving portion, and the current and the torque sensor The robot system according to claim 3, wherein the table is created in association with the detected load torque, and the limit current is calculated based on the table.
The robot controller, when screwing the male screw into the female screw after screwing the male screw and the female screw hole corresponding to the male screw, from the screwing operation start position of the male screw. While the male screw is positioned at the reference position between the screwing operation start position and the screwing operation end position, the rotation speed is higher than the rotation speed from the reference position to the screwing operation end position. The robot system according to claim 1, wherein the holding shaft driving unit is controlled.
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 a predetermined distance in the axial direction of the holding shaft,
A biasing portion that biases the holding shaft in a direction from the proximal end toward the distal end with respect to the holding shaft driving portion, and a relative position of the holding shaft in the axial direction of the holding shaft with respect to the holding shaft driving portion is detected. The robot system according to claim 1, further comprising: a position detection unit that performs the operation.
A holding shaft, the tip of which is formed in a shape complementary to the head of the male screw and engaged with the head of the male screw, so that the positional relationship around the axis of the male screw with respect to the male screw is fixed; A screw turning mechanism having a holding shaft drive unit that rotationally drives the holding shaft around an axis of the holding shaft;
A robot body that holds the screw turning mechanism and moves the screw turning mechanism;
A robot controller that controls the robot body and controls the holding shaft drive unit as an external shaft that performs work in cooperation with the robot body;
The robot controller controls at least one of a position and a rotation speed at a rotation angle position of the holding shaft when performing a fastening operation of the male screw engaged with the holding portion, and the holding shaft driving portion holds the holding shaft. Control of the robot system that controls the screw turning mechanism to stop the rotational drive of the holding shaft based on the determination whether or not the current for rotationally driving the shaft has reached the limit current corresponding to the target torque Method.
An engagement portion connected to the robot controller and engaged with the holding shaft, further comprising a torque sensor for detecting a load torque of the engagement portion;
The robot controller moves the holding shaft to engage the holding shaft with the engaging portion, and controls so that a predetermined current is supplied to the holding shaft driving portion, and the current and the torque sensor The robot system control method according to claim 7, wherein the table is created in association with the detected load torque, and the limit current is calculated based on the table.
The robot controller, when screwing the male screw into the female screw after screwing the male screw and the female screw hole corresponding to the male screw, from the screwing operation start position of the male screw. While the male screw is located at the reference position between the screwing operation start position and the screwing operation end position, the speed is higher than the rotational speed from the reference position to the screwing operation end position. The robot system control method according to claim 7 or 8, wherein the holding shaft drive unit is controlled.