JP2001005525A - Unmanned carriage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an unmanned carrier dispensable with an expensive constitution while obtaining high stopping precision. SOLUTION: A traveling mechanism 15 equipped with two driving wheels 18 to be driven by a driving motor 20 and four casters 19 is arranged at the bottom part of an unmanned carrier 11. A guide line 22 installed on a traveling path 13 for guiding the unmanned carrier 11 is constituted of a magnetic tape alternately polarized to an N pole and an S pole with prescribed pitches. A guide sensor 23 for steering for detecting the guide line 22 and a magnetic sensor 28 for detecting (counting) the magnetic pole of the guide line 22 are arranged at the bottom part of the unmanned carrier 11. A controller for traveling controls the speed of a driving motor 20 based on the detected value of an encoder 21 and the detected value of the magnetic sensor 28 while performing steering based on the detection signal of the guide sensor 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unmanned transport system in which a guideline is laid on a traveling path and an unmanned transport vehicle having a traveling mechanism is operated while autonomously traveling in accordance with the guideline.

[0002]

For example, in an automobile parts production line or the like, an automatic guided vehicle (or a mobile robot having a robot arm mounted on the automatic guided vehicle).
A system has been adopted in which various operations are performed while autonomously traveling between a plurality of facilities provided along a traveling path. Here, as schematically shown in FIG. 6, for example, the following traveling mechanism is provided at the bottom of the automatic guided vehicle 1 having a substantially rectangular box shape.

That is, at the bottom of the automatic guided vehicle 1, two drive wheels 2 are provided at the left and right of the intermediate portion, and casters 3 are provided at substantially four corners. Each of the drive wheels 2 is driven by a drive motor (not shown), and the rotational position (rotation speed) of the drive motor is detected by an encoder. Each drive wheel 2 (drive motor) is subjected to feedback control based on a detection value of the encoder by a travel control device mainly composed of a microcomputer.

A guide line 4 made of, for example, a magnetic tape is laid on the traveling path so as to extend in the traveling direction of the automatic guided vehicle 1. Is provided so as to have a detection width sufficiently large with respect to the width of the guide line 4 (for example, 5 cm). Thus, the travel control device controls the travel mechanism (drive motor 2) while steering the guide line 4 so as to pass through the center of the guide sensor 5, so that the automatic guided vehicle 1 moves along the guide line 4. It is designed to run autonomously.

In the above-mentioned traveling mechanism, the position (moving distance) of the automatic guided vehicle 1 or the position of the automatic guided vehicle 1 is determined from the encoder value due to circumstances such as slipping or idling of the drive wheels 2, fluctuation in diameter due to wear of the drive wheels 2, and meandering. There are circumstances in which the traveling speed cannot always be detected accurately. Therefore, in order to improve the stop accuracy of the automatic guided vehicle 1, generally, a stop marker 6 is provided at a stop position in front of the equipment on the traveling path, and a plurality of stop markers for detecting the stop marker at the bottom of the automatic guided vehicle 1 are provided. Provision of a marker sensor 7 has been performed.

[0006] According to this, a high stopping accuracy can be obtained by stopping the automatic guided vehicle 1 while the marker sensor 7 detects the stop marker 6. Alternatively, in some mobile robots, after the automatic guided vehicle is stopped, the stop position is corrected by detecting a marker (tag) on the equipment side by a CCD camera attached to the robot arm.

However, in the above configuration, in order to improve the stopping accuracy of the automatic guided vehicle 1, a stop marker 6 is provided on the traveling path or the equipment side, and a plurality of marker sensors 7 and CCDs are provided on the automatic guided vehicle 1 side. It is necessary to provide a camera, and there is a problem that the system becomes expensive. In addition, in order to stop the automatic guided vehicle 1 immediately after the marker sensor 7 detects the stop marker 6, the automatic guided vehicle 1 is caused to run at a low speed at a position where it is expected to approach the stop position, or is temporarily stopped. It is necessary to correct the stop position later, and there is a problem that time is lost and work efficiency is reduced. It is to be noted that the automatic guided vehicle 1 is inconvenient in that its position cannot be known if the automatic guided vehicle 1 is temporarily stopped in the middle of a traveling path due to, for example, an operator forcibly or avoiding danger during traveling. There was also.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an unmanned transport system that can achieve high stopping accuracy of an unmanned transport vehicle and can be configured with an inexpensive structure. is there.

[0009]

According to the present invention, there is provided an unmanned transport system in which a guide line to be laid on a traveling path is constituted by magnetic tapes which are alternately magnetized at predetermined pitches into N poles and S poles. A vehicle is provided with a magnetic sensor capable of detecting the magnetic poles of the magnetic tape, and the running and stopping of the running mechanism are controlled based on the detection of the magnetic sensor. Invention).

According to this, the magnetic sensor provided on the automatic guided vehicle counts the magnetic poles of the magnetic tape alternately magnetized to the N pole and the S pole at a predetermined pitch.
The moving distance and thus the position of the automatic guided vehicle on the traveling path can be detected, and the speed can be detected by differentiating the distance. At this time, by making the magnetization pitch sufficiently small, it becomes possible for the control means to perform a highly accurate stop control based on the detection of the magnetic sensor.

In this case, it is not necessary to provide a stop marker on the traveling path or the equipment side, or to provide a plurality of marker sensors or CCD cameras on the automatic guided vehicle side.
The magnetic tape alternately magnetized to the pole and the south pole is not so expensive as compared to the magnetic tape magnetized so that the polarity is different between the front side and the back side. While a high stopping accuracy can be obtained, an inexpensive configuration can be achieved.

In the present invention, the control means can control the stop position of the automatic guided vehicle based on the detection of the magnetic sensor (the invention of claim 2), and of course, controls the traveling speed of the automatic guided vehicle including the traveling speed. It is also possible (the invention of claim 3). In this case, even if the driving wheels of the traveling mechanism slip or run idle, the actual traveling speed of the automatic guided vehicle can be accurately detected, so that accurate speed control can be performed and, consequently, work can be performed. Efficiency can be improved.

Further, in a traveling mechanism having a configuration in which driving wheels are driven by a driving motor having an encoder, the driving motor is controlled while correcting the detection value of the encoder based on the detection of the magnetic sensor. (The invention of claim 4). According to this, higher-performance position and speed control for the drive motor can be realized.

Incidentally, the guideline is originally provided for guiding the automatic guided vehicle on the traveling path, and the automatic guided vehicle can be steered to follow the guideline based on the detection of the guideline by the guide sensor. It has become. In this case, a guide sensor for steering may be provided separately. However, if the magnetic sensor is configured to also serve as a guide sensor for steering (the invention of claim 5), the number of sensors can be reduced. Can be completed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, although not shown in detail, the unmanned transfer system according to the present embodiment is adopted, for example, in a production line of automobile parts, and the like.
An automatic guided vehicle 11 (to be described later, a mobile robot 1 in this embodiment)
2) (see FIGS. 1 and 2)
Along with a plurality of facilities.
Then, for example, while moving a plurality of mobile robots 12 autonomously on the traveling path 13 and sequentially stopping at the stop positions in front of the respective facilities, various operations such as workpiece transfer, assembly of parts, processing, and inspection are performed. Is to be performed.

FIG. 2 shows an external configuration of the mobile robot 12. The mobile robot 12 is an automatic guided vehicle 1.
1, an articulated (6-axis) robot arm 14
It is configured with. As shown in FIG. 1, the automatic guided vehicle 11 is formed in a substantially rectangular box shape that is slightly longer in the front-rear direction (left-right direction in the figure), and has a traveling mechanism 15 at the bottom thereof.
A traveling controller 16 (shown only in FIG. 3) for controlling the traveling mechanism 15, an arm controller for controlling the robot arm 14, and a power supply device (all shown in FIG. Z) is provided. In addition, on the outer wall (cover) of the automatic guided vehicle 11,
A plurality of obstacle sensors 17 (only a part is shown in FIG. 2) are provided.

The traveling mechanism 15 is, as shown in FIG.
The automatic guided vehicle 11 is provided with a pair of left and right drive wheels 18 at an intermediate portion in the front-rear direction at the bottom of the automatic guided vehicle 11 and is provided with casters (driven wheels) 19 at substantially four corners. As shown in FIG. 3, each of the drive wheels 18 is driven by a drive motor 20 via a speed reducer.
An encoder 21 for detecting the rotational position of the motor is mounted. As shown in FIG. 3, the drive motor 20
It is controlled by the traveling controller 16, and the detection value (rotational position signal) of the encoder 21 is input to the traveling controller 16.

Then, as shown in FIG.
A guideline 22, which will be described later, for guiding the automatic guided vehicle 11 is laid along the running direction on the top of the automatic guided vehicle 3. On the bottom of the automatic guided vehicle 11, the guideline 22 is located at the front and rear center. Guide sensors 23, 23
Is provided. The guide sensor 23 includes a plurality of magnetic sensor elements arranged in a horizontal direction, and has a detection width sufficiently large (for example, 20 cm) with respect to the width of the guide line 22 (for example, 5 cm). The detection signal of the guide sensor 23 is also input to the traveling controller 16.

The traveling controller 16 is mainly composed of a microcomputer, and as shown in FIG.
4, a ROM 25, a RAM 26, an input / output circuit 27, and the like. The traveling controller 16 includes a traveling path 13
And map data indicating the facilities (stop positions) and the like, and a traveling program is input. The traveling controller 16 controls the traveling mechanism 15 (drive motor 20) in accordance with them. Unmanned carrier 11
To run and stop.

At this time, the traveling controller 16 continuously moves (moves) the automatic guided vehicle 11 (mobile robot 12) from one facility (initial position) to the next facility (stop position). The speed pattern of the drive motor 20 is created from the distance (moving distance).
The speed pattern is, for example, a so-called trapezoidal pattern in which the speed is accelerated from a stopped state to a certain speed, the speed is maintained, and then the speed is reduced and stopped. Then, based on the speed pattern, each target speed is generated at a predetermined sampling interval (for example, 8 ms to 16 ms).
0, but in this case, the encoder 2
The present speed is calculated from the detected value of 1 and feedback control is performed.

In addition, the traveling controller 1
Reference numeral 6 indicates that the automatic guided vehicle 11 travels while the guide line 22 is steered so as to pass through the center of both guide sensors 23 based on signals from the guide sensors 23 and 23. In this embodiment, the steering of the automatic guided vehicle 11 is performed by the difference between the rotational speeds of the left and right drive wheels 18.

As shown in FIG. 1, the guide line 22 is composed of a magnetic tape which is alternately magnetized to a north pole and a south pole at a predetermined pitch (for example, 5 mm). On the other hand, for example, at the center of the bottom of the automatic guided vehicle 11,
A magnetic sensor 28 capable of detecting the magnetic pole of the guide line 22 is provided. The magnetic sensor 28 includes, for example, an NS pickup, and outputs a high-level signal when an N pole is detected (opposed), and outputs a low-level signal when an S pole is detected. As shown in FIG. 3, the detection signal of the magnetic sensor 28 is input to the traveling controller 16.

As will be described later in the description of the operation,
The traveling controller 16 functions as control means for controlling traveling and stopping by the traveling mechanism 15 (drive motor 20) based on the detection signal of the magnetic sensor 28. More specifically, in the present embodiment, the traveling controller 16 determines the traveling distance of the automatic guided vehicle 11 based on the moving distance obtained from the count values of the N pole and the S pole detected by the magnetic sensor 28 during traveling of the automatic guided vehicle 11. The speed of the drive motor 20 is controlled while correcting the detection value of the encoder 21.

Next, the operation of the above configuration will be described with reference to FIGS. As described above, the automatic guided vehicle 11
Is continuously driven from a certain facility (initial position) to the next facility (stop position).
Calculates the speed pattern from the distance between the positions while performing steering based on the detection signal of the guide line 22 from the guide sensors 23, 23, and generates a target speed for each unit time (sampling time). Perform feedback control.

Here, the rotational speed of the drive motor 20 (drive wheel 18) and the traveling speed of the automatic guided vehicle 11 should have a fixed relationship. There are circumstances in which the relationship fluctuates due to slip or idling, variation in diameter due to wear of the drive wheels 18, meandering, and the like. For this reason, the control based on only the detected value of the encoder 21 cannot guarantee high accuracy of the position (moving distance) and the traveling speed of the automatic guided vehicle 1.

In this embodiment, the traveling controller 16 is shown in FIG. 4 based on the detection value of the encoder 21 and the detection of the N pole and the S pole of the guide line 22 (magnetic tape) by the magnetic sensor 28. The processing of the procedure is executed for each unit time (sampling time), and the speed of the drive motor 20 is controlled. FIG. 5 is a control block diagram showing the state of control at that time.

That is, first, in step S1, a target speed is generated, and in the next step S2, the detected value (current value) of the encoder 21 is obtained. The detected value of the encoder 21 is a value accumulated from the previous detected value (accumulated value from the initial position). In step S3, the movement distance from the initial position based on the detection by the magnetic sensor 28 is obtained. This moving distance is obtained by accumulating the detection count values of the north pole and the south pole of the guide line 22 (magnetic tape).

In step S4, the value detected by the encoder 21 in step S2 is calculated in step S3.
Is corrected based on the moving distance detected by the magnetic sensor 28. Thus, the encoder value is set according to the actual moving distance of the automatic guided vehicle 11. Step S5
Then, the current speed is calculated based on the encoder value corrected in step S4, and in step S6, the speed (feedback signal) calculated in step S5
Is compared with the target speed obtained in step S1 to obtain a deviation, and the speed of the drive motor 20 is controlled based on the deviation.

By repeating the above processing every unit time, the drive motor 20 is controlled in accordance with the speed pattern, and finally, the automatic guided vehicle 11 (mobile robot 1)
2) The vehicle travels for a distance corresponding to the distance from the initial position to the next facility (stop position) and stops.
The automatic guided vehicle 11 can be accurately and accurately stopped with respect to the stop position. In this case, the error of the stop position is 5 mm or less, which is the magnetization pitch of the guide line 22.

Meanwhile, the automatic guided vehicle 11 (mobile robot 12) temporarily stops during the above-mentioned traveling, for example, forcibly by an operator, or based on the obstacle sensor 17 detecting an obstacle. May be done. In the present embodiment, even when the automatic guided vehicle 11 is stopped halfway, since the moving distance is detected by the detection of the magnetic sensor 28, the position of the automatic guided vehicle 11 can be determined, and then, when the automatic guided vehicle 11 moves to the next stop position, Therefore, speed control is performed.

As described above, according to the present embodiment, the guide lines 22 are formed of magnetic tapes which are alternately magnetized to the N pole and the S pole at a predetermined pitch, and the magnetic poles can be detected at the bottom of the automatic guided vehicle 11. By providing a simple magnetic sensor 28, high stopping accuracy of the automatic guided vehicle 11 can be obtained without providing a stop marker on the traveling path or on the equipment side or providing a plurality of marker sensors or CCD cameras on the automatic guided vehicle side. I was able to. In this case, it is not necessary to provide a stop marker on the traveling path 13 or the equipment side, or to provide a plurality of marker sensors or CCD cameras on the automatic guided vehicle 11 side. Since the cost is almost the same as that of magnetic tapes having different polarities), an extremely inexpensive system can be used as a whole.

In the present embodiment, the automatic guided vehicle 1 is expected to approach the stop position as in the related art.
It is not necessary to run at a low speed or to correct the stop position after stopping once, and it is possible to accurately stop the automatic guided vehicle 11 at the position to be stopped while decelerating at a predetermined deceleration, Efficient work can be performed without loss of time. Further, there is an advantage that the position of the automatic guided vehicle 11 can be determined without adding a special structure separately.

In the present embodiment, the encoder 21
The speed control of the drive motor 20 is performed while correcting the detection value of based on the detection of the magnetic sensor 28,
Higher-performance position and speed control of the drive motor 20 can be realized, and the automatic guided vehicle 11 can run at an optimum speed.

In the above embodiment, the speed of the drive motor 20 (running speed of the automatic guided vehicle 11) is controlled based on the detection of the magnetic sensor 28.
The position (movement distance) of the automatic guided vehicle 11 may be simply controlled based on the detection of No. 8. Also, the magnetization pitches of the N pole and S pole of the guide line (magnetic tape) may be set according to the target stopping accuracy. Although not shown, the guide sensor may be formed of a magnetic sensor capable of detecting a magnetic pole, that is, the magnetic sensor may be configured to also serve as a guide sensor for steering. The configuration can be simple and inexpensive.

In addition, for example, as a configuration of the traveling mechanism,
For example, drive wheels are provided at two diagonal locations, and casters are provided at two diagonal locations.
Various modifications are conceivable, such as a configuration in which steering is performed by a steering motor, and the present invention can be applied not only to a mobile robot but also to an unmanned transport vehicle that simply transports a work. The present invention can be implemented with appropriate modifications without departing from the scope of the invention.

[Brief description of the drawings]

FIG. 1 shows one embodiment of the present invention, and is a plan view showing an arrangement state of wheels and sensors at the bottom of an automatic guided vehicle.

FIG. 2 is a side view showing the appearance of the mobile robot.

FIG. 3 is a block diagram schematically showing an electric configuration of the automatic guided vehicle.

FIG. 4 is a flowchart showing a control procedure of a drive motor.

FIG. 5 is a control block diagram.

FIG. 6 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the drawing, 11 is an automatic guided vehicle, 12 is a mobile robot, 13
Is a traveling path, 15 is a traveling mechanism, 16 is a traveling controller (control means), 18 is a driving wheel, 20 is a driving motor, 21
Denotes an encoder, 22 denotes a guideline, 23 denotes a guide sensor, and 28 denotes a magnetic sensor.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) B65G 1/00 501 B65G 1/00 501C F term (reference) 3F022 KK20 LL07 NN21 NN32 QQ03 QQ04 3F059 AA01 BA03 BB07 DA05 DC08 DD01 DD08 FB11 FB15 FC00 FC02 3F060 AA01 CA12 GD14 5H301 AA02 AA09 BB05 CC02 EE06 EE12 EE27 FF04 FF17 FF21 FF27 GG12 HH01 HH10

Claims (5)

[Claims] 1. An unmanned transport system in which a guide line is laid on a traveling path, and an unmanned transport vehicle having a traveling mechanism is operated while autonomously traveling in accordance with the guide line. In the automatic guided vehicle, a magnetic sensor capable of detecting the magnetic poles of the magnetic tape is provided, and based on the detection of the magnetic sensor, An unmanned transfer system comprising a control means for controlling running and stopping by a running mechanism. 2. The unmanned transport system according to claim 1, wherein the control unit controls a stop position of the automatic guided vehicle based on the detection of the magnetic sensor. 3. The unmanned transport system according to claim 1, wherein the control unit controls the traveling speed of the automatic guided vehicle based on the detection of the magnetic sensor. 4. The driving mechanism is configured to drive a drive wheel by a drive motor having an encoder, and the control unit corrects the drive value while correcting a detection value of the encoder based on a detection of the magnetic sensor. The unmanned transfer system according to any one of claims 1 to 3, wherein the motor is controlled. 5. The unmanned transport system according to claim 1, wherein the magnetic sensor is configured to also serve as a steering guide sensor.