JP2002123316A - Unmanned carriage and its operation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an unmanned carriage and its operation control method which judges whether or not operation control for improving the positional relation between a fork and a loading palette is necessary and performs operation for improving the positional relation only when it is judged that the control is necessary. SOLUTION: This unmanned carriage 1 is equipped with an operation control means 6 which computes deviation x from a guide line 2 during a forward travel and corrects a travel posture according to the deviation x and stops traveling forward to perform loading operation or unloading operation. The operation control means 6 starts the loading operation or unloading operation at a forward-travel stop posture when the deviation at the stop of the forward travel is less than a prescribed value and repeats a backward travel or a forward travel by a set straight distance M until the deviation x becomes less than the prescribed value and starts the loading operation or unloading operation if the deviation x at the stop of the forward travel exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic guided vehicle and an operation control method for the same, and more particularly, to a method for controlling an operation performed by an automatic guided vehicle during a loading operation or an unloading operation, and a method for controlling the operation. And a configuration to be realized.

[0002]

2. Description of the Related Art In an automatic warehouse, etc., an unmanned transport system is employed, and although not shown, in this type of unmanned transport system, a guide line installed on a floor surface, that is, a large number of conductors, It is assumed that the automatic guided vehicle is guided by electromagnetic induction or magnetic induction from a guide line in which magnetic substances are linearly or curvedly spaced apart, and that the automatic guided vehicle can travel forward while following this guide line. Done. That is, the automatic guided vehicle is configured to include a vehicle body that travels in the front-rear direction and a fork that is attached to a front side of the vehicle body and moves up and down. For example, a guide line detecting means such as a hall element array in which a plurality of hall elements are arranged in parallel along the left-right direction of the vehicle body is provided.

[0003] The vehicle body provided in the automatic guided vehicle is provided with operation control means, and the operation control means is specifically a microcomputer. The microcomputer detects a deviation of the automatic guided vehicle with respect to the guide line, which is detected through a pair of front and rear guide sensors, that is, a lateral displacement of the automatic guided vehicle with respect to the guide line (hereinafter, referred to as a displacement). , Lateral displacement) and inclination angle (hereinafter, attitude angle)
Calculates the deviation expressed in the forward traveling, and adjusts the steering angle in accordance with the calculated deviation to correct the traveling posture and to cause the automatic guided vehicle to follow the guideway and travel forward. Running.

That is, in a general unmanned transport system, palletized luggage (hereinafter referred to as a loading pallet) is arranged at a predetermined position on a guide line, and then the unmanned transport vehicle is caused to travel forward. Then, an operation (lifting operation) of lifting the loading pallet with the fork of the automatic guided vehicle that has stopped traveling forward due to reaching the engaging position, which is the position immediately before the loading pallet, is performed.
In addition, after loading a pallet placed on a fork to a predetermined position on the guideway by an automatic guided vehicle, the work is performed to unload and place the pallet at a predetermined position on the floor surface (unloading work). It has become.

[0005]

By the way, in the unloading operation and the unloading operation by the automatic guided vehicle, especially in the unloading operation, the fork provided in the automatic guided vehicle and the load arranged on the guide line are used. Interlocking relationship with a stacking pallet, that is, relative interlocking relationship between a plurality of vertical rails connecting the upper and lower surfaces of the pallet to each other and a fork inserted between the vertical rails and lifting the loading pallet, in other words, Then, it is important to execute the operation control in consideration of the deviation of the automatic guided vehicle from the guide line when the forward running is stopped. However, in a microcomputer provided in a conventional automatic guided vehicle,
The actual situation is that the operation control in consideration of the relationship between the fork and the loading pallet is not executed.

On the other hand, when the loading pallet is arranged near the end point of bending of the guide line provided as a curved line, that is, the automatic guided vehicle has completed the turning operation while following the curved guide line. In a state where a sufficient linear distance cannot be secured to correct the traveling posture of the automatic guided vehicle, such as when a loading pallet is arranged at a position immediately afterward, the following operation control is also performed. I have. That is, despite the automatic guided vehicle reaching the position immediately before the loading pallet and stopping the forward traveling, the automatic guided vehicle is forcibly moved backward and forward over a linear distance of a predetermined length set in advance. This is an operation control in which a so-called switchback operation is performed, and the connection between the fork and the loading pallet is made as good as possible with the switchback operation.

[0007] Generally, it is considered that by performing such operation control, the deviation of the automatic guided vehicle with respect to the guide line is corrected, and the connection relationship between the fork and the loading pallet is improved. Have been. However, when the automatic guided vehicle stops traveling forward, it is not always ensured that a good relationship is ensured by the switchback operation without confirming the relationship between the fork and the loading pallet. In some cases, when the forward running is stopped, a favorable relationship is already secured, and in such a case, unnecessary switchback operation is forcibly executed, resulting in waste.

The present invention has been made in view of these inconveniences, and determines whether or not it is necessary to perform operation control for improving the relationship between a fork and a loading pallet, and determines whether or not it is necessary. It is an object of the present invention to provide an automatic guided vehicle configured to execute a switchback operation for improving a connection relationship only when the operation is performed, and an operation control method thereof.

[0009]

According to a first aspect of the present invention, there is provided an automatic guided vehicle which calculates a deviation with respect to a guide line installed on a floor during forward running, and corresponds to the calculated deviation. Operation control means for correcting the running posture by
When the forward running is stopped, the fork is loaded or unloaded by the fork, and the operation control means performs the forward running when the deviation when the forward running is stopped is equal to or less than a specified value. While starting the unloading or unloading work in the stopped posture, if the deviation when stopping the forward running exceeds the specified value, the preset linear distance until the deviation becomes equal to or less than the specified value , And then start the unloading operation or the unloading operation after repeating the backward traveling and the forward traveling.

An automatic guided vehicle according to a second aspect of the present invention is the automatic guided vehicle according to the first aspect, wherein the operation control means is provided when the number of repetitions of backward traveling and forward traveling exceeds a predetermined number of times set in advance. It is characterized in that the reverse traveling and the forward traveling are stopped and an abnormality warning is displayed.

According to a third aspect of the present invention, there is provided an operation control method for an automatic guided vehicle, wherein a deviation from a guide line installed on a floor surface is calculated during forward traveling, and traveling is performed in accordance with the calculated deviation. This is a method to execute the unloading or unloading work with the fork after stopping the forward traveling after traveling forward while correcting the posture, and when the deviation when the forward traveling is stopped is less than the specified value. Starts the unloading or unloading work with the forward running stopped,
If the deviation when the forward running is stopped exceeds the specified value, the reverse or forward running over a preset linear distance is repeated until the deviation becomes less than the specified value, and then the loading or unloading work is performed. It is characterized by starting.

According to a fourth aspect of the present invention, there is provided an automatic guided vehicle operation control method according to the third aspect, wherein when the number of repetitions of the backward traveling and the forward traveling exceeds a predetermined number of times set in advance, the reverse travel is performed. It is characterized in that traveling and forward traveling are stopped and an abnormality warning is displayed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a simplified configuration of the automatic guided vehicle according to the present embodiment and the operation at the time of unloading work, and FIG. 2 is an explanatory diagram schematically showing a deviation of the automatic guided vehicle with respect to the guide line. FIG. 3 is a flowchart showing a procedure of operation control executed in the automatic guided vehicle according to the present embodiment. In this embodiment, the operation control when the automatic guided vehicle performs the unloading work will be described.
The description of the operation control when performing the unloading operation is omitted, but it goes without saying that the same operation control is performed when performing the unloading operation.

The automatic guided vehicle 1 according to the present embodiment is used in an automatic guided vehicle system employed in an automatic warehouse or the like, and includes a guide line 2 installed on a floor, specifically, a large number of guided lines. A vehicle body 3 traveling in the front-rear direction while following a guide line 2 in which a derivative or a magnetic material is linearly or curvedly spaced apart from each other, and a fork 4 attached to a front side thereof and moving up and down. Have. At this time, at each of the front and rear positions of the vehicle body 3, a guide sensor 5 which is a guide line detecting means constituted by using a hall element array or the like is provided, while operation control is provided inside the vehicle body 3. A microcomputer 6 functioning as a means is provided. The microcomputer 6 is provided with a deviation x of the automatic guided vehicle 1 with respect to the guide line 2.
Is calculated during forward running, and the running posture of the automatic guided vehicle 1 is corrected in accordance with the calculated deviation x.

That is, the microcomputer 6 detects the deviation x of the automatic guided vehicle 1 with respect to the guide line 2 detected by the guide sensors 5 disposed in a pair in front and rear, that is, the lateral displacement y and the attitude angle θ of the automatic guided vehicle 1. The deviation x represented by the above is calculated during the forward traveling, and the automatic guided vehicle 1 follows the guide line 2 while moving forward while correcting the traveling posture by adjusting the steering angle in accordance with the calculated deviation x. The running operation control is being performed. More specifically, the guide sensor 5 provided on the vehicle body 3 is
As schematically shown in FIG. 2, the distance at which the preset origin A of the automatic guided vehicle 1, for example, the origin A which is the center position in the front-rear and left-right directions is shifted from the guide line 2 along the lateral direction. And the origin B set in advance of the forks 4 arranged in parallel as a pair of left and right, for example, the origin B which is the center position in the front-rear and left-right directions is the origin A of the automatic guided vehicle 1.
And the attitude angle θ which is an angle inclined from the angle.

Then, the lateral displacement y and the attitude angle θ detected by the guide sensor 5 are input to the microcomputer 6, and the microcomputer 6 determines that the distance L between the origins A and B is constant. In other words, the deviation x is calculated based on the following formula, that is, the deviation x = y + L · tanθ, and the traveling attitude of the automatic guided vehicle 1 is corrected in accordance with the calculated deviation x. ing.
The distance L between the origins A and B at this time is obtained in advance and stored in a memory (not shown) built in the microcomputer 6.

Further, the automatic guided vehicle 1 according to the present embodiment
Travels forward to the position immediately before the loading pallet 8 placed at a predetermined position on the guide line 2 and stops the forward traveling to move the loading pallet 8 placed at a predetermined position on the guide line 2 The work of picking up by the fork 4 is performed. Therefore, when the deviation x at the time when the forward running is stopped is equal to or smaller than a predetermined value, the microcomputer 6 installed in the automatic guided vehicle 1 performs the loading operation with the forward running stopped. On the other hand, when the deviation x when the forward running is stopped exceeds the specified value, two points that have been set in advance until the deviation x becomes equal to or less than the specified value, for example, the points C and C in FIG. Backward and forward travel over a straight distance M connecting point D,
It also has a function of executing an operation control for starting a loading operation by the fork 4 after repeating a so-called switchback operation.

That is, the memory of the microcomputer 6 at this time may impair the deviation x of the automatic guided vehicle 1 allowed during the loading operation, that is, the favorable relationship between the fork 4 and the loading pallet 8. A prescribed value for defining the upper limit of the deviation x of the automatic guided vehicle 1 is set in advance and stored. Therefore, the microcomputer 6 compares the deviation x of the automatic guided vehicle 1 when the forward running is stopped and the specified value with each other, and determines whether or not it is necessary to perform the switchback operation. The automatic guided vehicle 1 that is determined to need to perform the back operation repeats the switch back operation until the deviation x becomes equal to or less than the specified value. Although the deviation x of the automatic guided vehicle 1 is compared with the specified value here, the configuration may be such that the lateral displacement y and the attitude angle θ that are the deviation x are compared with the respective specified values. Of course.

Each time the unmanned guided vehicle 1 stops at the position immediately before the loading pallet 8 after the forward traveling due to the switchback operation is completed, it is determined whether the deviation x has become equal to or smaller than a specified value each time. And the switchback operation of the automatic guided vehicle 1 is repeated until the deviation x becomes equal to or less than the specified value, while the switchback operation is stopped when the deviation x becomes equal to or less than the specified value. Then, the unloading operation by the fork 4 is started. In the case where the loading pallet 8 is arranged near the bending end point of the guide line 2 installed as a curve, for example,
A linear guide line functioning as a switchback operation is provided separately from the original guide line 2.

By the way, unlimited repetition of the switchback operation is practically impossible and meaningless.
The memory of the microcomputer 6 provided in the automatic guided vehicle 1 according to the present embodiment stores a predetermined number of times set in advance, that is, a predetermined number of times for limiting the number of times of the switchback operation repeatedly. I have. When the microcomputer 6 determines that the number of repetitions of the switchback operation performed by the automatic guided vehicle 1 has exceeded the specified number, the backward traveling and the forward traveling accompanying the switchback operation of the automatic guided vehicle 1 are stopped, and In addition, operation control for displaying an abnormal alarm, such as a request for maintenance, by a buzzer, a signal light, or the like is to be executed. The specified number of times at this time is also stored in the memory of the microcomputer 6, and the microcomputer 6 performs the comparison with the specified number while counting the number of times the automatic guided vehicle 1 repeats the switchback operation.

Next, an operation control method at the time of unloading work of the automatic guided vehicle 1 according to the present embodiment will be described with reference to the flowchart of FIG. First, the automatic guided vehicle 1 that performs the unloading operation receives a transfer instruction from a host computer that controls the entire automatic guided vehicle system (step 1), and the automatic guided vehicle 1 that receives the transfer instruction. Starts the forward traveling after setting the count value of the switchback operation to zero (step 2). And
The automatic guided vehicle 1 follows the guide line 2 while calculating a deviation x with respect to the guide line 2 installed on the floor surface while traveling forward, and correcting the traveling posture in accordance with the calculated deviation x. The unmanned transport vehicle 1 that has traveled forward is located immediately before the loading pallet 8 disposed at a predetermined position on the guideway 2, for example, as shown in FIG.
The forward traveling is stopped when the vehicle reaches the engaging position, which is the point C indicated by (step 4).

Then, the microcomputer 6 provided in the automatic guided vehicle 1 determines whether the lateral displacement y of the deviation x in the automatic guided vehicle 1 that has reached the engagement position and stopped traveling forward is equal to or smaller than a specified value. (Step 5). If the lateral displacement y is equal to or smaller than the specified value, it is determined whether the attitude angle θ is equal to or smaller than the specified value (Step 6). ). And the attitude angle θ
The microcomputer 6 which has determined that the value is also equal to or less than the specified value starts the unloading operation by the fork 4 of the automatic guided vehicle 1 with the forward traveling stopped (step 7). Here, the lateral displacement y and the attitude angle θ are individually compared with the respective prescribed values, but the deviation x obtained by summing the lateral displacement y and the attitude angle θ is compared with the prescribed value. Of course, it may be possible.

On the other hand, when the microcomputer 6 determines that either the lateral displacement y or the posture angle θ exceeds the specified value, the microcomputer 6 adds 1 to the count value indicating the number of repetitions of the switchback operation (step S1). 8) And, after comparing the count value obtained by adding 1 with a predetermined number of times set in advance (step 9), when the count value is equal to or less than the predetermined number, the automatic guided vehicle reaches point D in FIG. 1 is caused to travel backward (step 10). Then, the microcomputer 6 determines whether or not the automatic guided vehicle 1 has reached the point D after completing the retreat traveling over the linear distance M connecting the point C and the point D ( In step 11), the microcomputer 6 that has determined that the backward traveling has been completed, causes the automatic guided vehicle 1 to travel forward over the linear distance M (step 3). That is, by the backward traveling and the forward traveling at this time, one switchback operation is performed over a linear distance M connecting the point C and the point D.

As a result, the automatic guided vehicle 1 travels forward again and then reaches the point C immediately before the loading pallet 8 (step 4), and the lateral displacement y and the attitude angle θ are defined. The microcomputer 6 determines again whether the value is equal to or less than the value (steps 5 and 6). Until it is determined that the lateral displacement y and the attitude angle θ are both equal to or smaller than the specified value, the switch is added while incrementing the count value by one, and comparing the count value with the specified number of times. The back operation is repeatedly performed, and the automatic guided vehicle 1 when the microcomputer 6 determines that the count value has exceeded the specified number of times while the switch back operation is being repeated is performed. Then, after the reverse traveling and the forward traveling due to the switchback operation are stopped, an abnormality warning is displayed (step 12).

[0025]

As described above, in the automatic guided vehicle and the operation control method according to the present invention, it is determined whether or not it is necessary to perform operation control for improving the relationship between the fork and the loading pallet. Is performed by the operation control means, and the switchback operation for improving the mutual relation is executed only when it is determined that the operation is necessary, so that the unnecessary switchback operation is forcibly executed. Not only is it possible to improve the cycle time after eliminating such waste, but also it is possible to obtain an effect that the engagement between the fork and the loading pallet can be easily and reliably brought into a favorable state. further,
When the configuration and the method according to the present invention are employed, it is possible to always maintain the accuracy of the fork and the loading pallet at a certain level or more, and as necessary, such as the mounting position and customer requirements. The advantage that the connection accuracy can be changed arbitrarily is also ensured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a simplified configuration of an automatic guided vehicle according to the present embodiment and an operation during a loading operation.

FIG. 2 is an explanatory diagram schematically showing a deviation of the automatic guided vehicle from a guide line.

FIG. 3 is a flowchart showing a procedure of operation control performed by the automatic guided vehicle according to the present embodiment.

[Explanation of symbols]

 Reference Signs List 1 automatic guided vehicle 2 guide line 6 microcomputer (operation control means) x deviation M linear distance

Claims (4)

[Claims] 1. An operation control means for calculating a deviation from a guide line installed on a floor surface during forward traveling, and correcting a traveling posture in accordance with the calculated deviation.
An unmanned guided vehicle that performs a fork unloading or unloading operation after stopping the forward running, wherein the operation control means is configured to move forward when the deviation when the forward running is stopped is equal to or less than a specified value. While starting the unloading or unloading work in the stopped posture, when the deviation when the forward traveling is stopped exceeds the specified value, the deviation is set in advance until the deviation becomes equal to or less than the specified value. An automatic guided vehicle characterized by starting a loading operation or an unloading operation after repeating a backward traveling and a forward traveling over a linear distance. 2. The operation control means according to claim 1, wherein when the number of repetitions of the backward running and the forward running exceeds a predetermined number of times, the backward running and the forward running are stopped and an abnormality warning is displayed. The automatic guided vehicle according to claim 1, wherein 3. A method according to claim 1, further comprising calculating a deviation with respect to the guide line installed on the floor during the forward traveling, and performing the forward traveling while correcting the traveling posture in accordance with the calculated deviation, and then stopping the forward traveling. The operation control method of the automatic guided vehicle that performs the unloading or unloading work with the above fork, and when the deviation when the forward running is stopped is equal to or less than a specified value, the posture of the forward running stopped. While starting the unloading or unloading work as it is, if the deviation when stopping the forward traveling exceeds the specified value, the vehicle must travel backwards over a preset linear distance until the deviation becomes less than or equal to the specified value. An operation control method for an automatic guided vehicle, wherein a loading operation or an unloading operation is started after repeating forward traveling. 4. The method according to claim 3, wherein when the number of repetitions of the backward running and the forward running exceeds a predetermined number of times set in advance, the backward running and the forward running are stopped and an abnormality warning is displayed. Operation control method for automatic guided vehicles.