JP3227950B2 - Travel control method for automatic guided vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control method for an automatic guided vehicle, and is particularly useful when applied to a front and rear wheel steering system.

[0002]

2. Description of the Related Art Automated guided vehicles are widely used in distribution systems for transporting various parts and products in factories and the like. This type of automatic guided vehicle generally travels along a guideway laid on the floor while detecting the guideway with a guide sensor provided on the vehicle body. At this time, the induction sensor
There are those that are sensitive to the magnetism generated by the taxiway, those that are sensitive to the light reflected on the taxiway, etc. These are used properly in consideration of the installation conditions of the system. In addition, several types of automatic guided vehicles having different driving / steering systems have been proposed, and one of them is a front / rear wheel steering system.

FIG. 2 is an explanatory view conceptually showing a back surface of an automatic guided vehicle I of a front and rear wheel steering system. As shown in the figure, a front wheel 2 and a rear wheel 3 which are steering wheels which also serve as driving wheels are provided on the front and rear center lines of the vehicle body 1, and the front and rear of the front wheel 2 and the rear wheel 3 are provided. Has front wheel guidance sensors 4 and 5 and rear wheel guidance sensors 6 and 7, respectively. Also, in the drawing, 8, 9, 10, and 11 are casters.

In the automatic guided vehicle I, an arrow A in the drawing
When traveling in the forward direction, the vehicle body 1 is guided using the front wheel guidance sensor 4 and the rear wheel guidance sensor 6, and when traveling in the reverse direction opposite to the arrow A direction, the front wheel guidance sensor 5 and the rear wheel are used. The control device is configured to guide the vehicle body 1 using the guidance sensor 7.

[0005] According to the automatic guided vehicle I of the front and rear wheel steering system, the same operation is performed in both forward and backward movements.
The vehicle travels following the traveling path with high accuracy.

By the way, as shown in FIG. 3, only the front wheels 13 arranged on the center line at the front of the vehicle body 12 are steering wheels which also serve as driving wheels, and are rear driven wheels on both left and right sides. The three-wheel type automatic guided vehicle II having the wheels 14 and 15 has traveling characteristics similar to those of the automatic guided vehicle I when moving forward, but swells at the R portion of the traveling path when moving backward. FIG. 4 illustrates this. In the figure, reference numeral 16 denotes a taxiway (travel path), and an oblique line descending to the lower left indicates an unmanned carrier during forward traveling.
The occupied area A accompanying the travel of II, and the diagonal line descending to the lower right indicates the occupied area B of the automatic guided vehicle II during the retreat. The traveling path of the automatic guided vehicle II expands so that the occupied area at the time of retreat becomes the occupied area B.

That is, an automatic guided vehicle I of front and rear wheel steering system
The greatest feature is that the same running characteristics as when traveling forward can be ensured when reversing.

[0008]

However, the automatic guided vehicle I of the front and rear wheel steering system according to the prior art has the following disadvantages.

1) Both the front wheels 2 and the rear wheels 3, which are the steered wheels, are steered by the information based on the corresponding front wheel guidance sensors 4, 5 and rear wheel guidance sensors 6, 7, so that the front and rear wheel guidance sensors are used. When (4, 6) and (5, 7) cannot detect the guidance path 16, that is, when any one of the front and rear wheel guidance sensors 4 to 7 is off the guidance path 16, steering cannot be instructed. . In this case, since the course-out signals are transmitted from the front and rear wheel guidance sensors 4 to 7, the control device continues to use the data of the steering instruction at the time of the previous sampling.

2) When the automatic guided vehicle I is inserted into the line, that is, when it is first placed on the taxiway 16, when the guidance sensors 4 to 7 of the steered wheels in the traveling direction are opposed to the taxiway 16. Depending on the state (steering direction) of the steered wheels that are not on the traveling direction side, the movement of the vehicle body 1 of the automatic guided vehicle I is difficult to predict and hinders the input operation.

More specifically, when the line is inserted, as shown in FIG. 5, for example, the traveling direction (forward direction) in this case
The front wheel guidance sensor 4 for the front wheel 2 that is the steered wheel on the
6, when the direction of the rear wheel 3, which is a steered wheel that is not on the traveling direction side, is in the illustrated state, the automatic guided vehicle I moves the rear part of the vehicle body 1 to the left (arrow B in the figure). Swing in the direction,
The front wheel guidance sensor 4 is deviated from the guidance path 16. That is, the state of the rear wheel 3 cannot be confirmed from above, and in the state shown in FIG.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, the present invention provides an automatic guided vehicle of a front and rear wheel steering system in which a guidance sensor for a steered wheel on a side opposite to a traveling direction detects a course-out, etc. It is an object of the present invention to provide a traveling control method for an automatic guided vehicle that can perform good and stable traveling control even when the vehicle is in operation and irrespective of the state of the steered wheels when the vehicle enters the line.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a structure in which a front wheel and a rear wheel, which are disposed at a front portion and a rear portion of a vehicle body and are both steered wheels, are provided. In the traveling control method of an automatic guided vehicle having guide sensors disposed on a vehicle body in the vicinity of the wheels and steering front and rear wheels along the guide paths while detecting the guide paths with the respective guide sensors, If the wheel and counter-traveling direction inductive sensors, which is a front wheel at the time of retraction after the time can not detect the induction path, characterized by the Turkey to hold the steering wheel of the counter-traveling direction to the neutral position.

[0014]

According to the present invention having the above-described structure, when a course out of a steered wheel in the opposite direction of travel is detected or the like, when the vehicle is moving forward,
The steered wheels on the side opposite to the traveling direction, which are the rear wheels and the front wheels at the time of retreat, are held at the neutral position.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

This embodiment is a traveling control method using a control device in the automatic guided vehicle I, and its flowchart is shown in FIG. As shown in the drawing, first traveling direction is equal to or a course out (see step S _1), if not off the track, performs steering instruction to steering wheels in the traveling direction (see step S ₂₎ . Then counter-traveling direction is determined whether off the track (see step S _3), if not off the track, the steering wheel anti-advancing direction to perform a steering instruction (see step S _4).

The above is the normal running control. In the case of forward traveling, the steered wheel on the traveling direction side is the front wheel 2 and the steered wheel on the opposite traveling direction side is the rear wheel 3, and whether or not the front wheel 2 is out of course is detected by the front wheel guiding sensor 4 and the rear wheel. The rear wheel guidance sensor 6 detects whether or not 3 is out of course. Thus, the automatic guided vehicle I travels along the taxiway 16.

[0018] When the course out of the traveling direction is detected in step S ₁ holds a steering wheel in the traveling direction of the steering angle of the previous sample (see step S _5). In the case of forward movement, the steering angle of the front wheels 2 is held at the value at the time of the previous sample.

Step S_ThreeCourse out on the opposite side
If a steering wheel is detected, the steering wheel in the opposite
Steer to the neutral position and hold it in this position (step
S ₆reference). In the case of forward movement, the rear wheel 3 is neutral
, And this state is maintained. This Neutra
As shown in FIG. 6, the front wheel 2
However, regarding the rear wheel 3, the rear wheel 3
It refers to a state on the center line L. Thus, this place
In this case, the three-wheel automatic guided vehicle shown in FIG.
It has similar running characteristics to the wheel steering type II. Sand
Only the front wheels 2 function as steering wheels, and the rear wheels 3
The posture is held at the position of the toral. Therefore, the vehicle body 1
Keeps running depending on the steering direction of the front wheels 2. By the way
The steering direction of the rear wheel 3 when the course out is detected is indeterminate
, An unexpected vibration occurs at the rear of the vehicle body 1.
there is a possibility.

As described above, according to the present embodiment, the steering in the forward direction is performed in the same manner as in the prior art, but the steering in the opposite direction is performed only when guidance is available,
Alternatively, the steering is performed according to the guidance sensor 5 (at the time of retreating), and if guidance is not possible, the steering is performed to the neutral position.

[0021]

[0022]

As described above in detail with the embodiments, according to the present invention, it is possible to prevent an unexpected swing of the vehicle body due to the out-of-course of the steered wheels in the anti-progression direction side, thereby achieving good traveling control. Can be done, and the entry into the line can do this well.

[0023]

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is an explanatory view conceptually showing a back surface of a front and rear wheel steering type automatic guided vehicle to which an embodiment of the present invention is applied.

FIG. 3 is an explanatory view conceptually showing a back surface of a three-wheel type automatic guided vehicle.

FIG. 4 is an explanatory diagram showing running characteristics of curved portions of a front-rear wheel steering system and a three-wheel automatic guided vehicle.

FIG. 5 is an explanatory view conceptually showing an aspect of a front and rear wheel steering type automatic guided vehicle when a line is inserted.

FIG. 6 is an explanatory diagram for explaining a neutral position of a steered wheel.

[Explanation of symbols]

 I Automatic guided vehicle 1 Body 2 Front wheel 3 Rear wheel 4,5 Front wheel guidance sensor 6,7 Rear wheel guidance sensor 16 Guideway

Claims (1)

(57) [Claims] 1. A vehicle having front and rear wheels which are disposed at a front portion and a rear portion of a vehicle body and which are both steering wheels, and further has an induction sensor disposed on the vehicle body in the vicinity of the front wheel and the rear wheel. A traveling control method for an automatic guided vehicle that steers a front wheel and a rear wheel along the guidance path while detecting the guidance path with each guidance sensor; Invitation
When the guide sensor can not detect the induction passage, the travel control method of the automatic guided vehicle, characterized the Turkey to hold the steering wheel of the counter-traveling direction to the neutral position.