JP4974934B2 - Control method of automatic guided vehicle - Google Patents

Description

  The present invention relates to a control method for an automatic guided vehicle that is used for assembling an article while traveling along a loop-shaped assembly line.

For example, in an assembly line for assembling an article such as an automobile, an automatic guided vehicle is usually used.
This type of assembly line has various work processes. Lightweight parts are attached while the automated guided vehicle is running, and heavy or large parts are attached using a robot. This is done with the automated guided vehicle stopped.

  By the way, when transporting articles with an automated guided vehicle, in order to improve work efficiency, the vehicle travels as fast as possible between each work station. In this case, depending on the distance between vehicles, Some have their speed controlled.

Specifically, there are provided a deceleration area with a sufficient inter-vehicle distance and a stop area with no sufficient inter-vehicle distance. When entering the vehicle, the vehicle is decelerated. When entering the stop area, the vehicle is stopped (see, for example, Patent Document 1).
JP-A-5-127747

  By the way, in the work station, there are a case where the work is performed while traveling and a case where the work is performed in a stopped state. For example, the automatic guided vehicle is stopped at a place where the assembled article is loaded or unloaded.

  However, many automated guided vehicles are traveling on the assembly line, and it is preferable to match the design standard work time, that is, the tact time, at each work station for work efficiency. If the control is attempted, there is a problem that due to the deceleration area, the start of the subsequent automatic guided vehicle is delayed, resulting in wasted time and actual work time being reduced.

  Therefore, an object of the present invention is to provide a control method for an automatic guided vehicle that can start the automatic guided vehicle at a work station without causing unnecessary time.

In order to solve the above-described problems, a control method for an automatic guided vehicle according to claim 1 of the present invention is guided along an assembly line in which a plurality of work stations are arranged, and has a predetermined length at a front portion. This is a control method for an automatic guided vehicle in which an obstacle detection sensor and a signal receiver each having a deceleration area and a stop area shorter than the deceleration area are provided, and a signal transmitter is provided at the rear. And
When a deceleration command or a stop command is issued during the traveling of the automatic guided vehicle, an approach signal is transmitted from a signal transmitter of the automatic guided vehicle to a signal receiver of the automatic guided vehicle behind,
When starting a stopped automatic guided vehicle,
Invalidate the deceleration area of the obstacle detection sensor provided in the automatic guided vehicle, and make the deceleration area valid when the front automatic guided vehicle does not exist in the deceleration area or exit from the deceleration area, And when the approach area signal from the front automatic guided vehicle is received when the deceleration area is invalid, the automatic guided vehicle is decelerated.

  According to the above control method, when starting the automatic guided vehicle, the deceleration area is invalidated, and when the approach signal is received when the deceleration area is invalidated, the deceleration is performed. A plurality of automatic guided vehicles can be started safely at the same time even if the interval between automatic guided vehicles is short. In other words, for example, it is possible to start the automatic guided vehicle at a work station where the automatic guided vehicle is stopped with a short interval, thereby shortening the useless time and increasing the actual working time. Can do. In other words, the tact time can be shortened as compared with the conventional control method, so that the work efficiency can be improved.

[Embodiment]
Hereinafter, a control method for an automatic guided vehicle according to an embodiment of the present invention will be described with reference to the drawings.
In an assembly line such as an automobile, an automated guided vehicle is used to assemble a large number of parts. First, a schematic configuration of an article assembly facility in which the automated guided vehicle is used will be described.

  As shown in FIG. 1, this kind of assembly line 1 is formed in a loop shape. Briefly, a first work station 11 for placing an assembly part of an automobile as an article on an automatic guided vehicle 2 and a work A plurality of, for example, a second work station 12 having a long space for a person to operate an assembly device or install a part using an assembly tool, and an automatic assembly machine such as a robot for automatically assembling a part are arranged. A third work station 13 and a fourth work station 14 and a fifth work station 15 for unloading the assembled articles from the automatic guided vehicle 2 are provided. As will be described later, each automatic guided vehicle 2 includes an obstacle detection sensor (also referred to as an object detection sensor) that prevents the rear automatic guided vehicle 2 from colliding with the automatic guided vehicle 2 (rear collision). As a detection area by this obstacle detection sensor, a deceleration area of a predetermined length (that is, there is a margin in the inter-vehicle distance) and a stop area that is shorter than this deceleration area (that is, there is no margin in the inter-vehicle distance) And are set.

In the second work station 12, the automatic guided vehicle 2 runs at a low speed, but in the remaining work stations 11, 13 to 15, the automatic guided vehicle 2 is stopped.
By the way, the first work station 11 that is the start position of the assembly line 1 and the fifth work station 15 that is the end position are arranged continuously (in other words, adjacent to each other). In 15, the automatic guided vehicle 2 is stopped and started in the state where the automatic guided vehicle 2 is approaching, so that a waste time is likely to occur in this portion. More specifically, in order to increase the work efficiency, it is necessary to make the tact time at each work station the same. For example, the tact time at the second work station 12 is different from the other work stations 11, 13 to 15. It is necessary to match the tact time at. By the way, it is necessary to stop the automatic guided vehicle 2 at the other work stations 11 and 13 to 15, and therefore the actual work time at these work stations 11 and 13 to 15 (hereinafter referred to as the actual work time) is Since the remaining time is obtained by subtracting the dead time from the stop state until reaching the predetermined speed, it is necessary to reduce the dead time as much as possible and increase the actual work time.

  For example, in the conventional control method, in order to prevent the automatic guided vehicles from colliding with each other, the distance between the automatic guided vehicles is widened so that the distance between the automatic guided vehicles is at least the deceleration area. In the state where the automatic guided vehicle 2 is stopped like the first operational station 11 and the fifth operational station 15, the automatic guided vehicle 2 ahead starts and leaves the deceleration area. Then, the automatic guided vehicle 2 in the rear (following) was started. Therefore, since the dead time is inevitably increased, it is difficult to increase the actual work time. That is, it has been difficult to shorten the tact time.

  In contrast, the control method of the present invention will be briefly described. When the automatic guided vehicle 2 in a stopped state is started, the deceleration area of the obstacle detection sensor 22 provided in the automatic guided vehicle 2 is invalidated. In other words, even when the front automatic guided vehicle 2 is present in the deceleration area of the rear automatic guided vehicle 2, the rear automatic guided vehicle 2 is started as long as it is not present in the stop area. is there. That is, the actual work time is increased by starting each automatic guided vehicle 2 from each work station 11, 13 to 15 at intervals as short as possible.

  Here, a schematic configuration of the automatic guided vehicle 2 used in the assembly line 1 will be described. In the following, the work stations 11 and 13 to 15 that perform work in a state where the automatic guided vehicle 2 is stopped may be referred to as a stop work station.

  The automatic guided vehicle 2 can be automatically guided along the assembly line 1 and can travel. The automatic guided vehicle 2 is guided by a magnetic member such as a magnet embedded in a floor surface and travel speed thereof. The stop position and the like are controlled by the control device 3 provided in the article assembly facility, and of course, the current traveling position and stop position of each automatic guided vehicle 2 are grasped, and start and stop are started. A command is transmitted (transmitted) to each automatic guided vehicle 2.

  In this article assembly facility, a collision prevention function (a rear-end collision prevention function) for preventing each automatic guided vehicle 2 from colliding with the automatic guided vehicle 2 in front is provided. More specifically, a start control mode for starting from a stop work station and a travel control mode for performing work in a normal travel state and a travel state after the start (that is, performed in the second work station 12) are provided. The commands for these control modes are transmitted from a travel command unit (not shown) provided in the control device 3.

  As shown in FIG. 2, in the front portion of the vehicle main body 21 of the automatic guided vehicle 1, a deceleration area A that can detect a front obstacle and has a predetermined length L <b> 1 (for example, 0.7 to 2 m) and Signal reception for receiving an approach signal from the obstacle detection sensor 22 in which a stop area B having a length L2 (for example, 0.2 to 0.3 m) shorter than the deceleration area A is set and the automatic guided vehicle 2 ahead. A signal transmitter 24 capable of transmitting an approach signal to the rear automatic guided vehicle 2 is provided at the rear portion of the vehicle main body 21. The obstacle detection sensor 22 uses an infrared light emitting diode, the deceleration area A has a vertically long elliptical shape, and the stop area B has a horizontally long elliptical shape. Of course, the lengths L1 and L2 and the widths W1 and W2 of the areas A and B for detection are also adjustable within a predetermined range. Moreover, as shown in FIG. 3, the detection signals from the obstacle detection sensor 22, the signal receiver 23, and other detection devices are input so that the automatic guided vehicle 2 collides with each other, that is, the automatic guided vehicle 2 behind The travel control unit 2a of each automatic guided vehicle 2 is provided with a function of preventing the automatic guided vehicle 2 from colliding and preventing another object, for example, an operator from colliding. Of course, the travel control unit 2a outputs a predetermined travel command (a so-called normal travel operation command) to the travel drive unit 21a on the vehicle body 21 side, and the control device 3 controls the entire facility. A function is also provided. In FIG. 3, reference numeral 25 denotes a traveling wheel provided on the vehicle main body 21.

  As shown in FIG. 4, an area in which the detection signal from the obstacle detection sensor 22 is input to the travel control unit 2 a to determine in which areas A and B the automatic guided vehicle 2 in front exists. The automatic guided vehicle 2 decelerates the automatic guided vehicle 2 when determined to be within the deceleration area A by the determining unit 31 and the area determining unit 31 and the automatic guided vehicle 2 when determined to be within the stop area B. A driving control mode for stopping the vehicle, and a start control mode for disabling only the deceleration area A by the obstacle detection sensor 22 and enabling only the stop area B, and switching to any mode according to an instruction from the control device 3 A mode control unit 32 is provided.

  As described above, the travel control mode is applied when traveling between work stations and when traveling on the second work station 12 that performs work in the travel state. It is applied during a period from the start of the stop state until passing through a predetermined section.

  In addition, as basic control for traveling in the automatic guided vehicle, starting and stopping at each stop work station are performed in synchronization. Of course, when the vehicle is started synchronously, the distance between the front unmanned transport vehicle 2 and the front unmanned transport vehicle 2 is shorter than that of the stop area B. If the vehicle enters B, the vehicle does not start, but if the front automatic guided vehicle 2 leaves the stop area B, the vehicle starts.

  When the automatic guided vehicle 2 is in a traveling state other than the case where the automatic guided vehicle 2 is traveling at a predetermined traveling speed, for example, at a maximum speed among the speeds set in a plurality of stages, that is, a deceleration command or a stop command is issued. An approach signal is transmitted from the signal transmitter 24 of the automatic guided vehicle 2 in the forward direction to the automatic guided vehicle 2 in the rear, and there is a failure of the automatic guided vehicle 2 in the rear. When the deceleration area A of the object detection sensor 22 is invalidated and when the approach signal is received, control is performed to perform deceleration. The stop function in the stop area B is made to work at any position.

  For example, if the automatic guided vehicle 2 is set to a stopped state and a traveling state of a plurality of stages (for example, 1 to 4 stages), a state other than the maximum speed set in the section (for example, 3 An approach signal is always transmitted to the automatic guided vehicle 2 at the rear when the vehicle is in a traveling state below the stage.

Based on the above-described configuration, a method for controlling the automatic guided vehicle will be described.
(1) The travel control mode is set for the second work station 12 and the travel section between the work stations (except for the fifth work station 15 and the first work station 11) except for the stopped state. . That is, when the front automatic guided vehicle 2 enters the deceleration area A of the obstacle detection sensor 22 of the rear automatic guided vehicle 2, this is detected by the obstacle detection sensor 22, and therefore the rear automatic guided vehicle 2 is detected. Is slowed down. Moreover, if it enters in the stop area B, the back automatic guided vehicle 2 will be stopped.
(2) On the other hand, in each of the stop work stations 11 and 13 to 15, for example, in the fifth work station 15 and the first work station 11, a plurality of automatic guided vehicles 2 stop at intervals of about the stop area B. When starting from a state where the vehicle is in a starting state, a start command is issued from the control device 3 to the travel control units 2a of the automatic guided vehicles 2 all at once.

At this time, the control mode in the traveling control unit 2a is the start control mode in which the deceleration area A is invalidated.
That is, in this state, the automatic guided vehicles 2 are started all at once with a short interval. That is, the dead time can be reduced as compared with the conventional control method.

  Of the automatic guided vehicles 2 started at short intervals, for example, the automatic guided vehicle 2 ahead detects an obstacle (of course, humans, other automatic guided vehicles are included), and a deceleration command is issued. When it is issued, an approach signal is transmitted from the signal transmitter 24, and when this approach signal is received by the signal receiver 23 of the automatic guided vehicle 2 behind, a deceleration command is issued and deceleration is performed. Of course, when the automatic guided vehicle 2 in the front enters the stop area B of the automatic guided vehicle 2 in the rear, the automatic guided vehicle 2 in the rear is stopped.

  That is, in the stop work stations 11 and 13 to 15 where the automatic guided vehicle 2 is stopped, even when the automatic guided vehicles 2 are started all at once, the distance between the automatic guided vehicles 2 is shortened (that is, as long as a stop area). Therefore, it is possible to improve the conveyance efficiency, that is, the work efficiency. Furthermore, in the stop work stations 11 and 13 to 15, when the distance between the automatic guided vehicles 2 is shortened, the operator can be prevented from entering the gap between the guided vehicles, which leads to improvement in safety.

  As described above, in each of the stop work stations 11 and 13 to 15, the traveling control unit 2 a of the automatic guided vehicle 2 sets the start control mode in which the deceleration area A is invalidated, and the deceleration is performed when the approach signal is received. Since it is made to carry out, it can start safely even if the space | interval of a plurality of automatic guided vehicles 2 is made simultaneously and the automatic guided vehicles are short. That is, since it is possible to start the automatic guided vehicle at a work station where work is performed in a stopped state at short intervals, it is possible to shorten the useless time and increase the actual work time. In other words, the tact time can be shortened as compared with the conventional control method, so that the work efficiency can be improved.

  By the way, in the said embodiment, although the control method at the time of starting an automatic guided vehicle from the stop work station where work is performed in the state where the automatic guided vehicle stopped has been described, for example, the automatic guided vehicle is in the middle of the work stations. It can also be applied to the start when the car stops.

  In the above embodiment, the invalidated deceleration area is validated when the front automatic guided vehicle exits the deceleration area. However, for example, it is preset in the stop work station portion. It can also be carried out when it goes out of the predetermined range S (shown in FIG. 1).

It is a top view which shows schematic structure of the article assembly equipment which concerns on embodiment of this invention. It is a top view which shows schematic structure of the automatic guided vehicle in the article | item assembly facility. It is a block diagram showing a schematic control configuration of the automatic guided vehicle. It is a schematic block diagram which shows the traveling control part in the control structure of the automatic guided vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Assembly line 2 Automated guided vehicle 2a Travel control part 3 Control apparatus 11 1st work station 12 2nd work station 13 3rd work station 14 4th work station 15 5th work station 21 Vehicle main body 21a Travel drive part 22 Obstacle detection Sensor 23 Signal receiver 24 Signal transmitter 31 Area determination unit 32 Mode control unit

Claims (1)

An obstacle detection sensor that is guided and traveled along an assembly line in which a plurality of work stations are arranged, and that has a deceleration area with a predetermined length and a stop area with a shorter length than the deceleration area at the front. A control method for an automatic guided vehicle in which a signal receiver is provided and a signal transmitter is provided in a rear part,
When a deceleration command or a stop command is issued during the traveling of the automatic guided vehicle, an approach signal is transmitted from a signal transmitter of the automatic guided vehicle to a signal receiver of the automatic guided vehicle behind,
When starting a stopped automatic guided vehicle,
Invalidate the deceleration area of the obstacle detection sensor provided in the automatic guided vehicle, and make the deceleration area valid when the front automatic guided vehicle does not exist in the deceleration area or exit from the deceleration area, A control method for an automatic guided vehicle, wherein the automatic guided vehicle is decelerated when an approach signal from a forward automatic guided vehicle is received when the deceleration area is invalid.

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