JP2814823B2 - Attitude control device of unmanned forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attitude control device for an unmanned forklift, particularly an unmanned guided vehicle.

[0002]

2. Description of the Related Art An unmanned vehicle that runs unmannedly on a route determined by a guide line while detecting a guide line laid on a floor surface in a factory or a warehouse by an induction antenna attached to the front and rear of a vehicle. 2. Description of the Related Art An unmanned forklift is known as a kind of an unmanned guided vehicle for loading / unloading and reloading a load.

[0003] The automatic guided vehicle has "normal" and "traffic".
Here, there is a traveling mode in which the vehicle travels at right angles to the normal traveling direction up to that point without changing its posture, as opposed to normal traveling such as forward traveling and reverse traveling. Such an unmanned guided vehicle capable of traveling in a transverse direction has an advantage that, when making a left turn or a right turn, the traveling space can be reduced as compared with a case in which the vehicle travels on a circular arc only by normal traveling.

Generally, such an automatic guided vehicle capable of normal traveling and traversing is composed of two drive wheels 2a and 2b arranged in series before and after the traveling direction of the vehicle body 1 (normal traveling direction).
And the two driven wheels 3a,
3b are arranged such that the row of drive wheels 2a, 2b and the row of driven wheels 3a, 3b are arranged side by side on the left and right.
The drive and the steering of each of the motors b are performed by the drive unit 7, so that the running and the posture control are performed.

Therefore, during normal traveling, the two drive wheels 2a and 2b are arranged in series in the front-rear direction in the traveling direction, and are similarly arranged in left and right parallel in the transverse traveling. Therefore, during normal traveling, the steering unit controls the front and rear drive wheels 2a and 2b by the drive unit 7 to control the steering attitude, and during traverse traveling, the drive wheels 2a and 2b are rotated by 90 °. The drive unit 7 controls the rotational speeds of the left and right drive wheels 2a and 2b, and controls the steering attitude based on the rotational difference.

[0006] In an unmanned forklift that normally performs a cargo handling operation in a lateral direction with respect to the traveling direction, a vehicle body 1
A fork F is provided at the center of one side, and the body 1 has a U-shape in plan view. Therefore, due to the shape of the body 1, two sets of induction antennas 5a and 5b are provided in the front and rear directions with respect to the normal traveling direction. It can be attached, but the induction antenna 6 in the traverse direction is 1
Often, only pairs can be mounted.

[0007] Therefore, during normal traveling, the two front and rear induction antennas 5a and 5b arranged on the vehicle body center line detect the induction line laid on the floor surface, and the front driving antenna 5a detects the deviation signal of the front induction antenna 5a. The wheel 2a is steered, and the rear drive wheel 2b is driven by a deviation signal of the rear induction antenna 5b.
The steering posture is stabilized by steering the vehicle, but when the vehicle is running sideways, the vehicle body 1 is not parallel to the guide line even when the guide antenna 6 is directly above the guide line because only one set of the guide antenna 6 is provided. In some cases (see FIG. 2), if the vehicle travels sideways, the posture is likely to be disturbed, and the traversing time increases by the amount of the posture control, which affects the cycle time of the entire system and the vehicle body deviates from the guidance line. However, there was a problem that the width of the passage had to be increased only.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and even if only one set of traversing induction antennas 6 provided on the vehicle body 1 is provided. In order to provide an unmanned forklift, the vehicle body 1 can travel along a predetermined route along a traversing guide line during traversing, suffice with a minimum necessary traveling space, and stabilize the posture during traversing. It is assumed that.

[0009]

Means for Solving the Problems An induction antenna 5a, 5b for normal running is provided in front and back of the vehicle body 1, and a traversing induction antenna 6 is provided on one of the right and left sides. In an unmanned forklift capable of traversing in the left-right direction, a pair of left and right non-contact sensors 4a and 4b are attached to the lower front and rear sides of the vehicle body 1, respectively. SUMMARY OF THE INVENTION An object of the present invention is to provide a posture control device for an unmanned forklift, wherein the posture control is performed by detecting a distance from a wall surface of the vehicle.

[0010]

1 to 3 show an embodiment of the present invention. 1 is a bottom view of the vehicle body during normal traveling, FIG. 2 is a bottom view of the vehicle body during traversing traveling, and FIG. 3 is a steering control block diagram.

In FIG. 1, reference numeral 1 denotes a vehicle body having a U-shape in plan view, and a fork F is provided on one side of a central portion of the vehicle body 1. Reference numerals 2a and 2b denote two drive wheels arranged in series before and after the traveling direction (normal traveling direction) of the vehicle body 1, and are driven and steered by the drive unit 7, respectively. Reference numerals 3a and 3b denote follower wheels which are also arranged in series in the front and rear direction, and are formed of caster tires which can rotate 360 °, and can be driven in any direction.

5a is an induction antenna for normal running provided at the lower center of the front surface 1a of the vehicle body 1;
An induction antenna for normal traveling provided at the lower center of the rear surface 1b, and a traversing induction antenna 6 provided at the lower center of one side surface 1c of the vehicle body 1, each being constituted by a pair of two antennas Then, by detecting a guide line laid on the floor, normal traveling in the front-rear direction and transverse traveling in the left-right direction can be performed along the guidance line. The above is as conventionally known.

A pair of left and right non-contact sensors 4a, 4a,
4b is attached, at the time of rampant, non-contact sensor 4a as shown in FIG. 2, 4b by detecting the distance d _1, d ₂ between the transverse direction right and left wall surfaces, the control circuit shown in FIG. 3 steering The posture can be controlled.

Reference numerals 7a and 7b denote driving motors for driving the driving wheels 2a and 2b, respectively. Reference numerals 8a and 8b denote servo drivers for the servomotors, which are based on detection signals of the induction antennas 5a and 5b during normal running, and the induction antenna 6 during traversing.
The servo motors 7a, 7b are controlled by the controller 9 in accordance with detection signals of the sensors 4a, 4b.
To accelerate and decelerate.

[0015]

The operation during normal running is omitted since it is well known in the art, and only the operation during traversing will be described. In addition, since the traveling direction changes by 90 ° during the traversing traveling, “front and rear” during normal traveling becomes “left and right”, and similarly “left and right” becomes “back and forth”. Therefore, the front surface 1a and the rear surface 1b of the vehicle body become the left and right side surfaces when the vehicle travels in the transverse direction. The front, rear, left, and right in the following description refer to front, rear, left, and right during traversing, unless otherwise specified.

During traversing, the drive units 2a and 2b are fixed in a state where they are rotated by 90.degree.
Is known to control the rotational speeds of the left and right drive wheels 2a and 2b and control the steering attitude based on the difference between the rotational speeds. 2, the vehicle body 1 may not be parallel to the guide line even when the guide antenna 6 is directly above the guide line laid on the floor.

In this case, the side surface 1a (or 1b) of the vehicle body 1
The distance to the wall surface detected by the pair of front and rear non-contact sensors 4a and 4b attached to the lower part of the table indicates different values from each other. For example, in FIG. If the distances from the side walls detected by the sensors 4a and 4b are d ₁ and d ₂ , the vehicle body 1 is inclined to the left in the traveling direction when d ₁ <d ₂ . Conversely, d ₁ >
When the d ₂ will be tilted to the right. In addition, the said wall surface refers to a wall surface in a broad sense, such as a wall or a rack stand.

The detection values d ₁ and d ₂ of the sensors 4a and 4b are input to a controller 9, and the controller 9 sends the left and right driving wheels 2a and 8b to the left and right servo drivers 8a and 8b.
A command is issued to accelerate and decelerate 2b so that d ₁ = d ₂ . As a result, the left and right traveling drive servomotors 7
The drive wheels 2a and 2b are accelerated and decelerated via the switches 7a and 7b to perform attitude control. When d ₁ = d ₂ , the rotation is started at a constant speed.

[0019]

According to the present invention, in an unmanned forklift capable of performing normal traveling in the front-rear direction and traversing in the left-right direction along the guide line, a pair of left and right non- The contact type sensors 4a and 4b are attached, and when the vehicle is traversing, the non-contact type sensor detects the distance to the left and right wall surfaces in the traversing direction to control the posture. Even if there is only one set 6, the vehicle body 1 does not lean to the left and right during traversing, and can travel on a determined route along the guide line, and it suffices with a minimum required traveling space, There is an effect that an unmanned forklift capable of stabilizing the posture at the time can be provided.

[Brief description of the drawings]

FIG. 1 is a bottom view showing a normal traveling state of an unmanned forklift of the present invention.

FIG. 2 is a bottom view showing a traversing traveling state.

FIG. 3 is a steering control block diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body 2a, 2b Driving wheel 3a, 3b Driving wheel 4a, 4b Non-contact sensor 5a, 5b Induction antenna for normal traveling 6 Induction antenna for traversing traveling 7 Drive unit 7a, 7b Servo motor for traveling drive 8a, 8b Servo driver 9 Controller

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G05D 1/00-1/12 B66F 9/24

Claims (3)

(57) [Claims] An induction antenna (5a, 5b) for normal traveling in front and rear of a vehicle body (1), and an induction antenna (6) for traversing traveling on one of the right and left sides, and a normal traveling antenna in a front-rear direction along a guidance line is provided. In an unmanned forklift capable of performing traveling and traversing in the left-right direction, a pair of left and right non-contact type sensors (4a, 4b) are attached to the lower front and rear sides of the vehicle body (1). An attitude control device for an unmanned forklift, wherein the attitude control is performed by detecting a distance between the left and right wall surfaces in a traversing direction by a type sensor. 2. A non-contact type sensor (4a, 4b) comprising a pair of left and right two sensors.
_2. The attitude control device for an unmanned forklift according to claim 1, wherein the control means controls the distances (d ₁ , d ₂ ) with the wall surface to be detected to be equal to each other when the vehicle travels in a transverse direction. . 3. The attitude control device for an unmanned forklift according to claim 1, wherein the attitude control is performed by accelerating and decelerating drive wheels (2a, 2b) located on the left and right sides of the vehicle body during traversing.