JP2000071183A - Mobile robot system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such dislocations of automatically guided vehicles from their working positions as result from high-speed movement of robot arms. SOLUTION: An automatically guided vehicle 3 has a vacuum mechanism 9 for fixing the vehicle 3 at its working position by means of air suction force. The vacuum mechanism 9 comprises suction nozzles 10 placed on the bottom of the automatically guided vehicle 3 and having vacuum pads 11, elevating actuators 12 for moving the suction nozzles 10 vertically, a compressor 13, an air ejector 14, a drive valve 16 interposed in a drive line 15, an open valve 19 interposed in a branch pipe 18 branching from a suction line 17, and a controller 6 for controlling those elements. A memory 8 stores data indicating the need of countermeasures against dislocation at each working position, according to which data the vacuum mechanism 9 is actuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile robot system in which a mobile robot moves on a traveling path in equipment and stops at a predetermined working position on the traveling path to perform a task by a robot arm.

[0002]

For example, in an assembly line of automobile parts, a mobile robot system in which an assembling operation is performed by a mobile robot having a robot arm mounted on an unmanned carrier has been adopted. In such a mobile robot system, a plurality of work stations are provided along a travel path on which the mobile robot moves, and the plurality of mobile robots are sequentially moved on the travel path and stopped at predetermined work positions in the respective work station portions. Then, the work by the robot arm is performed.

By the way, in this type of system,
In order to improve work efficiency, it is required to make the operation of the robot arm as fast as possible. However, the high-speed operation of the robot arm causes an increase in the reaction force acting on the automatic guided vehicle, and the automatic guided vehicle may slip and shift the stop position. Conventionally, as a technique for coping with such a displacement of the automatic guided vehicle, when a displacement occurs, the amount of the displacement is detected, and the operating position of the robot arm (the coordinates of the target position) is determined in accordance with the displacement. )
Was corrected.

However, in such a method of correcting the operating position of the robot arm, the correction operation is performed after the positional deviation of the automatic guided vehicle has stopped, so that time is lost for the correction and the working efficiency is reduced. There is a problem. Further, when the amount of displacement of the unmanned transport cart becomes large, the correction amount of the robot arm exceeds the operable range of the robot arm, and it may not be possible to cope with it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a mobile robot capable of effectively preventing the occurrence of displacement of an unmanned carrier at a work position due to a high-speed operation of a robot arm. It is to provide a system.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] In a mobile robot,
The cause of the displacement of the automatic guided vehicle caused by the operation of the robot arm is that the reaction force of the robot arm is larger than the static friction coefficient when the automatic guided vehicle is stopped. The mobile robot system according to the present invention is characterized in that a displacement prevention means for increasing the static friction coefficient of the automatic guided vehicle at the working position is provided (the invention of claim 1).

[0007] According to this, the position deviation preventing means can
The coefficient of static friction of the automatic guided vehicle at the work position can be made larger than the reaction force at the time of high-speed operation of the robot arm. Therefore, according to the first aspect of the present invention, there is an excellent effect that it is possible to effectively prevent the occurrence of displacement of the automatic guided vehicle at the work position due to the high-speed operation of the robot arm.

In this case, more specifically, the displacement preventing means may be constituted by a vacuum mechanism for fixing the automatic guided vehicle at the working position using pneumatic suction force (the invention of claim 2). Alternatively, the displacement prevention means may be constituted by a magnetic attraction mechanism for fixing the automatic guided vehicle at the working position using magnetic attraction (the invention of claim 3). Further, the displacement prevention means can be provided not only on the mobile robot but also on the equipment side (running road side) (the invention of claim 4).

By the way, the reaction force of the robot arm acting on the unmanned transfer truck differs depending on the work content of the robot arm, such as increasing when the robot arm moves largely at high speed. In other words, when the reaction force of the robot arm is small, there is no danger of the displacement of the automatic guided vehicle from the beginning, and it is not necessary to operate the displacement prevention means. Activating the prevention means leads to a loss of time and energy. Therefore, if the displacement prevention means is operated as necessary based on the work contents of the robot arm (the invention of claim 5), the displacement prevention means can function rationally.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment (corresponding to claims 1, 2, and 5) of the present invention will be described below with reference to FIGS. FIG. 1 schematically shows a configuration of a mobile robot 1 according to the present embodiment. In this embodiment,
The mobile robot 1 includes, for example, a traveling path 2 provided on a flat floor in equipment comprising an assembly line for automobile parts.
The assembling work and the like are sequentially performed at a plurality of work stations provided along the traveling path 2 while moving upward.

The mobile robot 1 is configured by mounting a robot arm 4 on an unmanned carrier 3. The automatic guided vehicle 3 has a rectangular box shape as a whole, a part of the upper surface serving as a work table, and a plurality of wheels 5 at the bottom. Although not shown, a traveling mechanism including a traveling motor for rotating and driving the wheels 5, a steering mechanism for steering the wheels 5, and a battery serving as a power source for driving the wheels 5 are provided in the automatic guided vehicle 3. ing. Further, the traveling mechanism and the steering mechanism are controlled by a controller 6 including a microcomputer and the like.

At this time, although not shown, a guide line for guiding the automatic guided vehicle 3 optically or magnetically, for example, on the traveling path 2 and a work station A stop mark for stopping at a predetermined work position corresponding to is provided. On the other hand, the automatic guided vehicle 3 is provided with a guidance sensor for detecting the guidance line and a stop sensor for detecting the stop mark. Thus, the controller 6 moves the automatic guided vehicle 3 (mobile robot 1) along the guidance line (travel path 2) based on the detection of the guidance sensor and the stop sensor, and sets the predetermined work position. To stop.

On the other hand, the robot arm 4 is composed of an articulated arm in this case, and has a hand 7 at its tip for holding a work (not shown) and performing a predetermined operation.
The robot arm 4 is also controlled by the controller 6. At this time, the controller 6
A memory 8 in which a control program, an operation program, and the like are stored is connected, and the controller 6 causes the robot arm 4 to execute operations such as assembling, processing, and inspecting a work. The operation of the robot arm 4 at this time is made as fast as possible, and the working efficiency is improved.

In this embodiment, the unmanned carrier 3
Is provided with a vacuum mechanism 9 as a displacement prevention means for increasing the coefficient of static friction with the traveling path 2 when the automatic guided vehicle 3 stops at the work position. Hereinafter, the vacuum mechanism 9 will be described.

That is, first, at the bottom of the automatic guided vehicle 3,
In this case, two suction nozzles 10 are provided. Each of the suction nozzles 10 has a cap-shaped vacuum pad 11 made of a soft material at a distal end (lower end) thereof, and is lifted and lowered by a lifting actuator 12. The elevating actuator 12 is controlled by the controller 6, so that the suction nozzle 10
The (vacuum pad 11) moves up and down between a descending position that is in close contact with the floor surface of the traveling path 2 and a rising position that is located above the floor surface. At this time, although not shown, a limit switch is provided at the tip of the vacuum pad 11, and the operation of the limit switch detects the grounding to the floor.

On the other hand, a compressor 13 and a pneumatic ejector 14 serving as a negative pressure source for the suction nozzle 10 are provided in the automatic guided vehicle 3. The compressor 13
Has a suction side open to the outside (atmosphere), and a discharge side
The pneumatic ejector 14 is connected to a primary flow side via a driving pipe 15, and a driving valve 16 is provided in the driving pipe 15. The compressor 13 and the drive valve 16 are also controlled by the controller 6. Note that the compressor 13 is also used for other purposes required in the mobile robot 1.

The discharge flow side of the pneumatic ejector 14 is open to the outside (atmosphere), and the secondary flow side of the pneumatic ejector 14 is connected to the suction nozzle 10 via a suction pipe 17. ing. In the middle of the suction pipe 17, a branch pipe 1 whose other end is open to the outside (atmosphere)
8 is connected to one end, and an opening valve 19 is provided at an intermediate portion of the branch pipe 18. The opening valve 19 is also controlled by the controller 6.

As a result, while the compressor 13 is driven, the driving valve 16 is opened and the opening valve 19 is closed, so that the inside of the suction nozzle 10 is made to have a negative pressure (vacuum). The vacuum pad 11 is configured to suck the floor portion in contact with the vacuum pad 11. When the driving valve 16 is closed and the opening valve 19 is opened, the inside of the suction nozzle 10 (vacuum pad 11) returns to the atmospheric pressure and the suction is released.

The vacuum mechanism 9 constructed as described above
Is controlled by the controller 6. At this time,
As will be described later, the controller 6 keeps the suction nozzle 10 at the raised position based on the work program stored in the memory 8 during normal times such as when the mobile robot 1 is moving, and also controls the drive The valve 16 is closed and the opening valve 19 is opened, so that the vacuum mechanism 9 is inactivated.

The vacuum mechanism 9 is operated when the mobile robot 1 (the automatic guided vehicle 3) stops at a predetermined working position on the traveling path 2. More specifically, the suction nozzle 10 is lowered to the lowering position, the compressor 13 is driven, the driving valve 16 is opened, and the opening valve 19 is closed. Thus, the pneumatic suction force of the vacuum mechanism 9 fixes the automatic guided vehicle 3 at the working position.

Also, in this embodiment, the vacuum mechanism 9 is not operated unconditionally at all work positions. Is stored, and the vacuum mechanism 9 is operated in accordance with the data. In this case, the data on the necessity of the countermeasure for preventing the displacement is determined in advance by the user side and described in the work program. For example, the mobile robot 1 is actually tested and the robot arm 4
It is determined that a countermeasure to prevent the displacement is necessary when the reaction force greatly acts on the automatic guided vehicle 3, such as when the device operates largely at high speed.

Next, the operation of the above configuration will be described with reference to FIG. The flowchart in FIG. 2 shows a control procedure (position shift control routine) regarding the vacuum mechanism 9 executed by the controller 6 when the mobile robot 1 (the unmanned transport vehicle 3) stops at the work position. That is, when the mobile robot 1 (the unmanned carrier 3) stops at the work position (Yes in step S1), data on the necessity of measures for preventing displacement is taken in (step S1).
2).

Here, when the measures for preventing displacement are not required (No in step S3), the vacuum mechanism 9 is not operated, and the operation by the robot arm 4 is executed as it is (step S4). In this case, the work content of the robot arm 4 does not require any measures for preventing positional displacement, that is, the work content of the robot arm 4 alone is more than the reaction force of the operation of the robot arm 4 only by the static friction force caused by the wheels 5. It goes without saying that the automatic guided vehicle 3 does not shift due to this.

On the other hand, if a countermeasure for preventing displacement is required (Yes in step S3), first, the lifting actuator 12 is operated to lower the suction nozzle 10 (step S5), and the suction nozzle 10 is mounted on the vacuum pad 11. When the ground switch on the floor of the traveling path 2 is detected by the limit switch (Yes in step S6), the suction nozzle 10
Is stopped (step S7). Then, in this state, the compressor 13 is driven, and the drive valve 16
Is opened and the opening valve 19 is closed (step S8).

Thus, the compressed air from the compressor 13 is supplied to the primary flow side of the pneumatic ejector 14 by the driving pipe 1.
5, the secondary flow side of the pneumatic ejector 14 has a negative pressure, the air in the suction nozzle 10 is sucked through the suction pipe 17, and the vacuum pad 11 is in a state of sucking the floor surface. Thus, the coefficient of static friction of the automatic guided vehicle 3 with respect to the floor surface is increased by the suction force due to the operation of the vacuum mechanism 9, and the automatic guided vehicle 3 is fixed at the working position.

Here, it takes a certain amount of time for the inside of the suction nozzle 10 to reach a negative pressure equal to or less than the predetermined value. Therefore, after elapse of a predetermined time (step S9), the operation by the robot arm 4 is executed (step S9). S10). in this case,
Although the reaction force due to the high-speed operation of the robot arm 4 is relatively large, and the static friction force of only the wheels 5 may cause the unmanned transport vehicle 3 to move, the operation of the unmanned transport vehicle 3 by operating the vacuum mechanism 9 The coefficient of static friction at the position can be made sufficiently large, and the unmanned transport vehicle 3 can be prevented from shifting.

When the operation of the robot arm 4 is completed, the driving valve 16 is closed and the opening valve 19 is opened (step S11). As a result, the function of the pneumatic ejector 14 is stopped, and outside air is supplied into the suction nozzle 10 through the branch pipe 18, and the inside of the suction nozzle 10 (vacuum pad 11) returns to the atmospheric pressure to release suction. Become like

Also in this case, it takes some time for the inside of the suction nozzle 10 to return to the atmospheric pressure. Therefore, after a certain time has elapsed (step S12), the lifting / lowering actuator 12 is operated to move the suction nozzle 10 to the ascending position. (Step S13). After a while, mobile robot 1
The (automated guided vehicle 3) is moved on the traveling path 2 toward the next work position.

As described above, according to the present embodiment, since the vacuum mechanism 9 for fixing the automatic guided vehicle 3 to the working position by the pneumatic suction force is provided, the stationary state of the automatic guided vehicle 3 at the working position is provided. The coefficient of friction can be made larger than the reaction force at the time of high-speed operation of the robot arm 4, and as a result, an excellent effect that the occurrence of displacement of the automatic guided vehicle 3 can be effectively prevented can be obtained. be able to.

Also, in this embodiment, when the reaction force of the robot arm 4 becomes large based on the work content of the robot arm 4 at the work position (work station), there is a possibility that the position of the automatic guided vehicle 3 may be shifted. Only the vacuum mechanism 9 is operated, so that the automatic guided vehicle 3
It is possible to obtain an advantage that the vacuum mechanism 9 can be rationally operated without incurring a loss of time or energy in the case of the work content in which there is no possibility of the position shift.

In the above embodiment, the compressor 13 and the pneumatic ejector 14 are used as the negative pressure source of the suction nozzle 10.
However, a configuration in which the suction side of a compressor (vacuum pump) is directly connected to the suction nozzle 10 may be used. Further, the negative pressure source may not be provided inside the automatic guided vehicle 3 but may be provided outside (on the equipment side), and an air pipe may be connected to the automatic guided vehicle 3 from outside.

Next, the second embodiment of the present invention will be described with reference to FIG.
(Corresponding to claim 3) will be described. This second
This embodiment differs from the first embodiment in the configuration of the displacement prevention means. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and only different points will be described below.

FIG. 3 shows a mobile robot 21 according to this embodiment.
Is schematically shown, and the automatic guided vehicle 22 includes:
As a displacement preventing means, a magnetic attraction mechanism 23 for fixing the automatic guided vehicle 22 at a working position using a magnetic attraction force is provided. In the present embodiment, the traveling path 2
4 (floor floor) is made of a soft magnetic material, in this case an iron plate.

The magnetic attraction mechanism 23 is used for the automatic guided vehicle 2
2 is provided with an electromagnet 25 provided at the bottom of the base 2 and a lifting actuator 25 for raising and lowering the electromagnet 26. The electromagnet 25 and the lifting actuator 26
Are controlled by a controller 27 composed of a microcomputer or the like. And the controller 27
Is stored in the memory 28 which is connected to the data indicating whether or not it is necessary to take a measure for preventing displacement at each work position.

In the above configuration, the mobile robot 21
When the (unmanned transfer carriage 22) stops at the work position and performs work by the robot arm 4, if it is necessary to take measures to prevent the displacement, the elevation actuator 26 is operated to lower the electromagnet 25 and move the floor to the floor. In the contact state, electricity is supplied to the electromagnet 25 to attract the floor surface. With this,
By the magnetic attraction force by the operation of the magnetic adsorption mechanism 23,
The automatic guided vehicle 22 is fixed at the working position.

Therefore, according to this embodiment as well, the first
As in the embodiment, the unmanned carrier 2
Since the magnetic attraction mechanism 23 for fixing the robot 2 to the work position is provided, the coefficient of static friction at the work position of the automatic guided vehicle 22 can be made larger than the reaction force of the robot arm 4 during high-speed operation. As a result, it is possible to obtain an excellent effect that the displacement of the automatic guided vehicle 22 can be effectively prevented.

In each of the above embodiments, the displacement prevention means (the vacuum mechanism 9 and the magnetic attraction mechanism 23) are provided on the mobile robots 21 side. However, the vacuum mechanism and the magnetic attraction mechanism are provided on the equipment side (floor). (Invention of claim 4), whereby the configuration of the mobile robot (unmanned carrier) can be simplified (reduced in size and weight). . In addition, the present invention can be appropriately modified and implemented without departing from the gist.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of a mobile robot according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a position shift control routine.

FIG. 3 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;

[Explanation of symbols]

In the drawings, 1, 21 is a mobile robot, 2, 24 is a traveling path,
Reference numerals 3 and 22 denote automatic guided vehicles, 4 a robot arm, 5 wheels, 6 and 27 a controller, 8 and 28 a memory, 9 a vacuum mechanism (a displacement preventing means), and 23 a magnetic attraction mechanism (a displacement preventing means). ).

Claims (5)

[Claims] A mobile robot having a robotic arm mounted on an unmanned carrier and moving along a traveling path in equipment and stopping at a predetermined working position in the traveling path to perform work by the robot arm. The mobile robot system according to claim 1, further comprising a position deviation preventing unit configured to increase a coefficient of static friction of the automatic guided vehicle at the work position. 2. The apparatus according to claim 1, wherein said displacement preventing means comprises a vacuum mechanism for fixing said automatic guided vehicle at a working position by using a pneumatic suction force.
Mobile robot system as described. 3. The mobile robot system according to claim 1, wherein said displacement prevention means comprises a magnetic attraction mechanism for fixing said automatic guided vehicle at a working position using magnetic attraction. . 4. The mobile robot system according to claim 1, wherein said displacement prevention means is provided on a facility side. 5. The mobile robot system according to claim 1, wherein the displacement prevention unit is operated as needed based on the work contents of the robot arm.