JPH11246198A - Multi-axis automatic guided vehicle and method for preventing unbalanced load - Google Patents

Abstract

(57) [Summary] [Problem] To provide an automatic guided vehicle that is capable of efficiently preventing an unbalanced load of an automatic guided vehicle with a significantly smaller amount of information, and that is superior in running stability in a high-speed transport state as compared with the related art. To provide. SOLUTION: In an automatic guided vehicle configured to be capable of arbitrarily entering and exiting a fixed transfer table for transferring a plurality of heavy objects, and loading heavy objects and transporting the same on a trackless basis, each of the unmanned transport vehicles is independently driven under the vehicle body. A wheel device of six or more wheels provided so as to be independently steerable, a plurality of heavy load tables provided on the upper part of the vehicle body, and a lifting device arranged on the vehicle body for raising and lowering heavy objects through the mount tables, A measuring device for measuring a suspension pressure of a hydraulic device for supporting the axle of the wheel device; and a calculation control device for calculating a correction direction and a correction amount of the bogie based on a measurement value from the measurement device and issuing a correction command.

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 for transporting a cylindrical heavy object such as a steel plate coil and a method for preventing an unbalanced load, and more particularly to a method for stably loading a plurality of heavy objects in a stable state. And a method for preventing unbalanced load thereof.

[0002]

2. Description of the Related Art An unmanned transport vehicle for a heavy object such as a coil is configured to be multi-axial due to restrictions on wheel load and road load resistance. High speed and stable running becomes difficult due to the occurrence of slips and slips. To increase the allowable range of eccentric load,
It is possible to cope with an increase in the number of axles and an increase in the diameter of the tire, but this is not preferable in terms of economy and operation because the body becomes large.

[0003] As a countermeasure against an unbalanced load in the automatic guided vehicle, conventionally, means as disclosed in Japanese Patent Application Laid-Open No. 7-323944 has been proposed. That is, in this conventional example, after the transport vehicle enters the lower part of the portal-type transfer table on which the coil is mounted, the lifter device incorporated in the vehicle body is operated to receive the coil, and then the vehicle is driven. Is moved out of the transfer table and conveyed along the desired line. When the vehicle enters the transfer table, the length (axial length) of the transferred object (coil) is detected, Calculation is performed based on the detected value and data such as the number, weight, and arrangement of the conveyed objects that have been input in advance, and the center of gravity of the coil substantially coincides with the center of the conveyed vehicle, thereby suppressing the unbalanced load.

[0004]

The above-mentioned JP-A-7-32
Although the invention of Japanese Patent No. 3944 has certainly obtained satisfactory results in that a heavy object such as a coil is conveyed in a stable state without an unbalanced load, there is room for further improvement in the following points. Information about the goods in advance (number of goods, weight, material,
It is necessary to input the sheet thickness and the arrangement order of the conveyed products) to the control device, so that the amount of information handled by the entire conveyance system increases, and the operation is cumbersome and complicated. The calculation while entering the transfer table becomes complicated, which leads to a decrease in the entry speed and a decrease in the operation efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its main object to efficiently prevent an unbalanced load of an automatic guided vehicle with a significantly smaller amount of information. It is another object of the present invention to provide an automatic guided vehicle having excellent running stability in a high-speed transport state as compared with the related art.

In the above-described conventional automatic guided vehicle, a four-wheel independent drive / four-wheel independent steering type structure is basically disclosed in a vehicle body having one lifter device. That is, it is an automatic guided vehicle having at least six axles and a plurality of heavy-loading parts, and also in this regard, the two are different from each other in the basic structure that is assumed.

[0007]

According to a first aspect of the present invention, there is provided a multi-axle automatic guided vehicle according to the first aspect of the present invention, which arbitrarily moves in and out of a fixed transfer table for transferring a plurality of heavy objects. An automatic guided vehicle configured to be capable of loading and carrying heavy objects on a trackless basis, comprising: a wheel device of six or more wheels provided at a lower portion of the vehicle body so as to be independently driven and steerable; and a plurality of wheel devices provided at an upper portion of the vehicle body. A heavy object mounting table, a lifting device arranged on a vehicle body for raising and lowering a heavy object through the mounting table, a measuring device for measuring a suspension pressure of an axle supporting hydraulic device of the wheel device, and a measuring device. And a calculation control device that calculates a correction direction and a correction amount of the bogie based on the measurement values of the bogie and issues a correction command.

According to a second aspect of the present invention, there is provided a method for preventing an eccentric load of a multi-axis automatic guided vehicle, wherein a plurality of heavy objects can be arbitrarily moved in and out of a fixed transfer table and a heavy object can be loaded. In the method for preventing unbalanced load of an automatic guided vehicle transporting untracked, the pressure of the hydraulic suspension of each axle when each heavy object is loaded is detected, and the center of gravity of the entire vehicle body is determined based on the detected pressure value. When the amount of eccentricity of the position is out of the allowable range, the moving amount and the moving method from the position of the center of gravity to within the allowable range are calculated, and once the loaded state of the heavy object is released, the moving amount and the moving direction are adjusted. And adjusting the position of the transport vehicle to load the heavy object again.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an automatic guided vehicle according to the present invention will be described with reference to FIG. 1. FIG. 1 (a) is a plan view of the automatic guided vehicle and a transfer table, and FIG. 1 (b) is (a). (C) is a side view (at the time of entering the transfer table). In the illustrated example, the number of wheels (the number of axles) is set to 8 (one wheel is a double wheel, so the number of tires is 16), and a steel sheet coil is shown as a heavy object to be conveyed. However, the present invention is not limited to this, and six or more wheels may be employed, and the conveyed object may be a cylindrical heavy object other than the coil or another heavy object.

In FIG. 1, an automatic guided vehicle 1 has eight wheel devices 3 at a lower portion of a vehicle body 2, and each of the wheel devices 3 is supported by an axle supporting cylinder 4. A recessed mounting table 5 for holding a steel sheet coil is provided at the upper part of the vehicle body 2, and three lifters (6) for raising and lowering the coil are provided at substantially the center of each mounting table 5.
a, 6b, 6c). The coil mounting table 5 mounts the coil such that the coil axis is substantially orthogonal to the traveling direction of the carrier. Each of the wheel devices 3 is configured to be independently driven / independently steered so that the automatic guided vehicle 1 can travel in all directions, that is, forward, backward, left, and right. Automatically travels while detecting.

When a steel sheet coil is mounted on such an automatic guided vehicle 1 and is transported to a predetermined position, a plurality of steel sheet coils 7 are mounted at appropriate positions on the traveling path of the vehicle. The automatic transfer vehicle 1 is temporarily stopped at the position of the transfer table 8 and receives the steel sheet coil 7. As shown in the drawing, the transfer table 8 has a structure in which a coil mounting portion is formed in a gate-like shape having a space in the middle so as to project horizontally, and the transport vehicle 1 can traverse and sufficiently enter under the projecting portion. It has become.

The operation of the present invention will be described below with reference to the flowchart of FIG. 2 together with FIG. As shown in FIG. 1, when it is desired to transfer three steel plates 7 having different diameters placed on a transfer table 8 onto the automatic guided vehicle 1, first, the traveling and steering of the wheel device 3 of the guided vehicle is performed. After moving the automatic guided vehicle 1 to the front of the transfer table 8 (step A in FIG. 2), the wheel device 3 is steered to change the direction of the wheels and to traverse, so that the guided vehicle is moved into the transfer table 8. The vehicle enters (step B) and stops at a preset reference position (step C). Next, each lifter 6a ~
6c, the lifter moves the coil 7 on the transfer table.
, But automatically stops at its upper limit position (steps D and E). In this state, all of the coil load is applied to the transport vehicle. Here, as shown in FIG. 3, the suspension pressure of the hydraulic cylinder 4 provided in each wheel device 3 is measured by the measuring device 9 (Step F), and this measurement is performed. The center of gravity of the entire automatic guided vehicle 1 is calculated by the arithmetic and control device 10 based on the value, and the amount of eccentricity of the position of the center of gravity is obtained. If the amount of eccentricity is within the allowable range, the automatic guided vehicle 1 is traversed in the reverse direction and moves out of the transfer table 8 (step G), the lifter is lowered at a position before the transfer table, and stopped at the lower limit position. Then, the coil transfer is started (steps H, I, J, K).

In FIG. 3, reference numeral 12 denotes a steering motor provided at a lower portion of the vehicle body 2, which transmits a driving force of the motor 12 to a rotary bearing 14 via a transmission gear 13, and controls the rotary bearing 14 to a predetermined position. The steering is performed by changing the direction of the wheels 3 by rotating the wheels 3 by an angle.

If the eccentricity is out of the allowable range, the arithmetic and control unit 10 calculates a correction amount and a correction direction in which the eccentricity is within the allowable range, and sends the command to the driving unit 11 of the wheel device 3. (Step L). If the amount of eccentricity does not fall within the allowable range due to the predetermined multiple corrections here, it is determined that correction is impossible, lifter lowering, lifter lower limit detection, abnormality is notified to the upper system, for example, a steel plate with a crane Perform coil transfer (steps M to
O). On the other hand, when the correction can be performed once or a plurality of times, the lifter lowers and the lifter lower limit is detected, the correction traverse of the carrier by a predetermined amount is performed, and the traverse is completed (steps P to
S). Next, returning to step D, the above-described eccentricity detection operation is repeated until the eccentricity falls within the allowable range.

However, since the load in the front-rear direction of the automatic guided vehicle is determined by the weight of the heavy object (steel coil 7) placed on the transfer table 8, the arrangement of the heavy object placed on the transfer table 8 is shown in FIG. It is necessary to determine the arrangement of the heavy objects so that the deviation amount of the center of gravity in the longitudinal direction is equal to or less than the allowable value in advance in the upper computer, but the allowable amount of fluctuation in the center of gravity position in the longitudinal direction is compared with the left and right direction. In order to increase the size, it is sufficient to check only the pressure of the lifters 6a to 6c.

[0016]

The effects obtained by the present invention described above are as follows. According to the present invention, since the eccentric load is adjusted after loading the transported object, the amount of information handled by the entire transport system is reduced as compared with the conventional method which requires input of information on the transported object in advance. According to the present invention, uneven load can be effectively prevented, so that uneven wear of wheels is reduced, and high-speed and stable conveyance is realized.
Parts life is extended. Contributes to high-speed and stable transport of heavy objects, especially steel coil. The accuracy of placing heavy objects on the transfer table can be reduced,
The work efficiency of the upper loading crane is improved.

[Brief description of the drawings]

FIG. 1A is a plan view of an automatic guided vehicle and a transfer table,
(B) is a front view of (a), (c) is a side view (at the time of entering a transfer board).

FIG. 2 is a flowchart of a method for preventing uneven load according to the present invention.

FIG. 3 is an explanatory diagram of a hydraulic cylinder and a drive unit of the wheel device in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unmanned guided vehicle 2 Body 3 Wheel device 4 Hydraulic cylinder 5 Coil mounting table 6a-6c Lifter 7 Steel plate coil 8 Transfer table 9 Suspension measuring device 10 Calculation / control device 11 Wheel drive unit 12 Steering motor 13 Transmission gear 14 Rotating bearing

Claims (2)

[Claims] 1. An automatic guided vehicle configured to be able to freely enter and exit a fixed transfer table for transferring a plurality of heavy objects, and to load and transport the heavy objects on a trackless basis. A wheel device of six or more wheels provided so as to be independently steerable, a plurality of heavy object mounting tables provided on the upper part of the vehicle body, and a lifting device arranged on the vehicle body for raising and lowering the heavy objects through the mounting table. A measuring device for measuring a suspension pressure of a hydraulic device for supporting the axle of the wheel device, and a calculation control device for calculating a correction direction and a correction amount of the bogie based on a measurement value from the measurement device and issuing a correction command. A multi-axle automatic guided vehicle characterized by: 2. A method for preventing unbalanced load of an automatic guided vehicle that can arbitrarily enter and exit a fixed transfer table that transfers a plurality of heavy objects, and that loads and transports the heavy objects without a track. The pressure of the hydraulic suspension of each axle at the time of loading is detected, the center of gravity of the entire vehicle body is obtained based on the detected pressure value, and when the amount of eccentricity of the position of the center of gravity is outside the allowable range, the allowable range from the position of the center of gravity is After calculating the amount of movement and the method of movement into the interior, once releasing the loading state of heavy objects,
A method for preventing an unbalanced load of a multi-axis automatic guided vehicle, comprising: adjusting the position of the carrier according to the moving amount and the moving direction;