JP2001278593A - Unmanned forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an unmanned forklift capable of always performing the loading work and the unloading work in the optimal condition by automatically adjusting the stop position of a car body required to the loading and unloading work in response to the weight of a load to be placed on a fork. SOLUTION: This unmanned forklift is provided with a speed detecting means 41 for detecting the elevating speed V of a load 16, a load computing means 42 for computing the weight W of a load 16 on the basis of a value of the elevating speed V of the load 16 detected by the speed detecting means 41, a tilted variable computing means 43 for obtaining the tilted variable Δ of a mast 10 corresponding to the weight W of the load 16 computed by the load computing means 42, and a loading and unloading position adjusting means 44 for adjusting at least one of a traveling stop position of a car body 2 and a reach position of a fork 11 in response to the tilted variable Δ of the mast 10 obtained by the tilted variable computing means 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unmanned forklift for automatically raising and lowering various kinds of luggage, and more particularly to a technique for appropriately controlling loading and unloading according to the weight of luggage.

[0002]

2. Description of the Related Art In general, an unmanned forklift used for transporting and unloading various kinds of luggage has been demanded for labor saving and has good convenience such as small turnability.
It is becoming increasingly used.

In such a conventional unmanned forklift, a controller 3, a magnetic sensor 5, a traveling encoder 6, a lifting encoder 7 and the like are provided on the vehicle body 2 as shown in FIG. A fork 11 is provided on the standing mast 10 so as to be able to move up and down. The controller 3 detects the magnetic body 14 laid on the floor surface 12 with the magnetic sensor 5 and outputs the detection output of the traveling encoder 6. The vehicle body 2 is controlled so as to autonomously travel along a predetermined track on the basis of the control signal, and the lifting operation of the fork 5 is controlled based on the detection output of the lifting encoder 14.

[0004] For example, when carrying a load 16 placed on a pallet 15 to a shelf 19 of a predetermined rack 18, first, the pallet 15 is supported by a fork 11 and then the predetermined The vehicle travels to the place where the rack 18 is installed, and then approaches the rack 18 while moving the fork 11 up and down and holding the luggage 16 on the shelf 19 at a predetermined height.

Subsequently, based on the detection output of the traveling encoder 6, the controller 3 stops the forward traveling when it reaches a reference position separated from the rack 18 by a predetermined distance L,
Next, the fork 11 is gently lowered, and the pallet 1
5 is put down on the shelf 19 of the rack 18. As a result, the transportation of the luggage 16 is completed.
Retreat.

[0006]

By the way, in such an unmanned forklift, the fork 11
When performing work such as loading and transporting with the fork 1
A mast 10 for supporting the vertical movement of the fork 11
Deformed according to the weight of the luggage 16 placed on the vehicle body 2 and tilted forward of the vehicle body 2 from the vertical position. That is, normally, when there is no load when the luggage 16 is not placed on the fork 11,
The mast 10 is set to incline backward slightly to the vehicle body 2 side from the vertical position with respect to the floor surface 12. However, when the weight of the load 16 is large, the mast 10 together with the fork 11 Incline forward.

Therefore, when the vehicle body 2 is stopped based on the detection output of the traveling encoder 6, the amount of inclination of the baggage 16 varies depending on the weight of the baggage 16. There is a disadvantage that the unloading operation cannot be performed smoothly.

That is, when the mast 10 has a large forward inclination, the luggage 16 is placed extra deeper than a predetermined position on the shelf 19, or when the mast 10 has a small forward inclination, the pallet 15 When taking out the luggage 16 by inserting the fork 11, the insertion amount of the fork 11 is insufficient and the pallet 15 cannot be lifted in a stable state.

In the prior art, in order that the stop position of the vehicle body 2 with respect to the rack 18 is always appropriate,
A rack beam sensor 20, which is a kind of proximity sensor, is provided at the lower base end of the fork 11, and the forward movement of the vehicle body 2 is stopped when the rack beam sensor 20 detects the position of the shelf 19. Have been.

[0010] However, when such a rack beam sensor 20 is provided, the sensor 20 is separately required, resulting in an increase in cost. In the case where the fork 11 is lowered to the floor surface 12 for loading, the sensor 20
May come into contact with other foreign matter on the floor surface 12 and damage the sensor 20. Further, when the load 16 is placed on a fixed base on which the rack 18 is not provided, the fixed base may not be detected by the rack beam sensor 20, and the position at which the vehicle body 2 should be stopped may be determined. You will not be able to judge.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and according to the weight of a load placed on a fork, a stop position of a vehicle body required for loading / unloading or a reach of a fork is required. It is an object of the present invention to provide an unmanned forklift capable of automatically adjusting a position and always loading and unloading luggage in a proper state.

[0012]

The present invention has the following features to attain the object mentioned above.

That is, in the unmanned forklift according to the first aspect, a speed detecting means for detecting a lifting speed of the load, and a weight of the load is calculated based on the magnitude of the lifting speed of the load detected by the speed detecting means. Load calculating means to calculate the inclination of the mast corresponding to the weight of the luggage calculated by the load calculating means, and the inclination of the mast obtained by the tilt calculating means It is characterized by comprising a loading / unloading position adjusting means for adjusting at least one of the traveling stop position of the vehicle body and the reach position of the fork according to the amount.

Thus, when the load placed on the fork is raised or lowered, the speed at the time of ascending becomes slower when the load is large, and conversely, the speed becomes faster at the time of descending. Can be calculated, and the amount of inclination of the mast can be obtained based on the calculation result. Then, the travel stop position of the vehicle body or the reach position of the fork is automatically adjusted according to the magnitude of the inclination amount, so that the loading / unloading operation of the luggage can always be performed in an appropriate state.

The unmanned forklift according to claim 2 is of a reach type in which the mast moves in the front-rear direction, and includes speed detecting means for detecting the speed of lifting and lowering the load.
A load calculating means for calculating the weight of the load based on the magnitude of the lifting speed of the load detected by the speed detecting means, and a load corresponding to the load calculated by the load calculating means. In accordance with the inclination amount calculating means for obtaining the inclination amount of the mast, and the inclination amount of the mast obtained by the inclination amount calculating means,
And a loading / unloading position adjusting means for adjusting the reach position of the fork.

Thus, when lifting or lowering the load placed on the fork, the speed at the time of ascending becomes slower when the load is large, and conversely, the speed becomes faster at the time of descending. Can be calculated, and the amount of inclination of the mast can be obtained based on the calculation result. Then, the reach position of the mast is automatically adjusted according to the magnitude of the inclination amount, so that the work of loading and unloading the luggage can always be performed in an appropriate state.

Normally, the forklift is provided with a lifting encoder which generates a pulse train of a number corresponding to the lifting distance of the fork to detect the lifting height of the fork on which the load is placed. As described above, if this existing lifting encoder is used as a part of the speed detection means, it is particularly convenient because it is not necessary to separately provide a pressure sensor or the like for detecting the load.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining loading and unloading of luggage by an unmanned forklift according to an embodiment of the present invention. In FIG. 1, parts corresponding to those of the prior art shown in FIG. Is attached.

In FIG. 1, reference numeral 1 denotes an entire unmanned forklift, 2 denotes a vehicle body, and 3 denotes the unmanned forklift.
For automatic operation control of the vehicle body 32
, Running wheels provided on the left and right of the front side of the vehicle, 33 is a single driving steering wheel provided behind the vehicle body 2, and 8 is a driving steering wheel 33.
Is a steering device for steering the drive steering wheel 33.

Reference numeral 10 denotes a mast erected on the front side of the vehicle body 2, 11 denotes a fork mounted on the mast 10 so as to be able to move up and down, and 16 denotes a load placed on the fork 11. Reference numeral 7 denotes a lifting encoder for detecting the lifting height of the fork 11. The lifting encoder 7 and the fork 11 are connected by a wire 30, and an intermediate portion of the wire 30 is guided by a guide roller 31. It has become so. A lifting motor 22 drives the fork 11 up and down.

As the lifting encoder 7, for example, a rotary encoder is applied. As the fork 11 driven by the lifting motor 22 rises, the wire 30 is pulled out from the lifting encoder 7, and when the fork 11 descends. As a result, the wire 30 is taken up by the lift encoder 7, whereby the lift encoder 7 rotates according to each operation, and accordingly, a pulse train of a number corresponding to the lift distance of the fork 11 is generated from the lift encoder 7. It is supposed to be.

Reference numeral 5 denotes a magnetic sensor provided on the vehicle body 2 for autonomously traveling the unmanned forklift 1, and reference numeral 14 denotes a metal magnetic body embedded in the floor 12 for autonomous traveling of the unmanned forklift 1.

FIG. 2 is a block diagram schematically showing a control system for performing automatic operation control in the unmanned forklift 1.

In the figure, 3 is a controller, 7 is a lifting encoder, 8 is a traveling drive device, 9 is a steering device, and 22 is a lifting motor.

The traveling drive unit 8 includes a traveling motor 23 for driving the drive steering wheel 33, a traveling motor drive unit 24 which is a rotation drive circuit of the traveling motor 23, and a traveling motor 23.
The traveling encoder 6 for detecting the traveling distance from the rotation speed of the vehicle is provided.

The controller 3 is composed of a microcomputer or the like, and includes a memory 26 and an arithmetic control unit 27 composed of a CPU and the like. The memory 26 is a ROM,
The memory 26 is pre-stored in the memory 26 with data indicating the relationship between the weight W of the luggage 16 and the lifting / lowering speed V of the fork 11 under each load as shown in FIG. And luggage 16 as shown in FIG.
Are stored in the form of a table together with the data indicating the relationship between the elevation height H of the fork 11 and the amount of inclination Δ of the mast 10 according to the weight W of the fork 11. Here, the tilt amount Δ is a horizontal movement distance when the mast 10 is tilted from a reference position (for example, a vertical position) as shown in FIG.

That is, when the load 16 placed on the fork 11 is raised and lowered, when a large load is applied to the fork 11, the speed at the time of ascending becomes slow, and conversely, the speed at the time of descending becomes fast. As shown in FIG. 3, the memory 26 stores data indicating the relationship between the load W and the ascending / descending speed V when the load 16 is lifted, as shown in FIG. (Shown by a solid line in the figure) and
Data indicating the relationship between the load W and the ascending / descending speed V when the load 16 is lowered (indicated by a broken line in the figure) is stored. Further, since the inclination amount Δ of the mast 10 is affected not only by the height H of the fork 11 but also by the weight W of the load 16, the memory 26 stores the load 16 of the load 16 as shown in FIG. Each weight W (W0, W1, W2,
..), The data indicating the relationship between the elevation height H of the fork 11 and the inclination amount Δ of the mast 10 (dashed lines, solid lines,
(Indicated by a dashed line).

The arithmetic control unit 27 is provided with the above-mentioned units 8,
9, 22,..., A speed detecting means 41 for detecting an ascending / descending speed V of the load 16, and a load 16 based on the magnitude of the ascending / descending speed V of the load 16 detected by the speed detecting means 41. Load calculating means 42 for calculating the weight W of the luggage, in accordance with the weight W of the baggage 16 calculated by the load calculating means 42, a tilt amount calculating means 43 for obtaining a tilt amount Δ of the mast 10 corresponding thereto, An operation control unit 44 for controlling the travel stop position of the vehicle body 2 according to the inclination amount Δ of the mast 10 obtained by the inclination amount calculation unit 43 is included. It should be noted that the above-mentioned lifting encoder 7 is connected to the speed detecting means 4.
1. Included in part.

Next, a description will be given of a control operation for loading / unloading an appropriate load according to the weight of the load 16 in the unmanned forklift 1 having the above configuration with reference to a flowchart shown in FIG.

For example, when carrying a load 16 placed on a pallet 15 to a shelf 19 of a predetermined rack 18, first, the pallet 15 is supported by the fork 11 and the predetermined rack 18 is Drive to the place where is installed. During this traveling, the controller 3
The magnetic body 14 laid on the vehicle 2 is detected by the magnetic sensor 5, and based on the detection output of the traveling encoder 6, the traveling drive device 8 and the steering device 9 are controlled so that the vehicle body 2 travels autonomously along a predetermined track. Control.

The controller 3 drives the elevating motor 22 to raise or lower the fork 11 while the vehicle body 2 approaches the rack 18 (step 1). When the fork 11 is raised and lowered, the controller 3 detects the weight W of the luggage 16 being transported based on the detection output of the lifting encoder 7.

That is, when the fork 11 on which the load 16 is loaded is raised or lowered by the drive control of the lifting motor 22, the lifting encoder 7 rotates accordingly.
As shown in FIG.
Pulse trains of a number corresponding to one elevating distance are generated. In this case, for example, as shown in FIG. 7A, if the number of pulses per unit time T is large, the ascending / descending speed of the fork 11 is fast, and if the number of pulses is small in FIG. Has become.

Then, this pulse train is taken into the arithmetic control unit 27, so that the speed detecting means 41 of the arithmetic control unit 27
Counts the number of pulses N per unit time T output from the elevation encoder 7 (step 2), and calculates the elevation speed V of the luggage 16 based on the following equation (step 3). It should be noted that since the elevating speed V changes with distance or time, a speed after a predetermined time has elapsed from the start of elevating is calculated. V = kN / T (where k is the moving distance of the fork corresponding to one pulse)

Subsequently, the load calculation means 42 of the arithmetic and control unit 27 determines the load 16 based on the value of the lifting / lowering speed V obtained based on the above equation and the data of FIG. The weight W is calculated (steps 4 and 5).
That is, when the load 16 is lifted by the lifting motor 22, the load calculating unit 42 determines the value of the load W corresponding to the lifting speed V obtained by the equation using the data indicated by the solid line in FIG. 3. On the contrary, the luggage 1 is
When lowering 6, the value of the load W corresponding to the elevating speed V obtained by the equation is determined using the data shown by the broken line in FIG.

The inclination calculating means 43 calculates the elevating distance (= kN) of the fork 11 from the number of pulses N output from the elevating encoder 7, and calculates the predetermined distance of the predetermined rack 1 of the rack 18.
When the fork 11 is held at a height at which the load 16 and the pallet 15 can be placed on the
The vertical height H from the first reference position is obtained (step 6).

Subsequently, the inclination amount calculating means 43 stores the figure stored in the memory 26 from both the current lifting height H of the fork 11 and the weight W of the load 16 placed on the fork 11. The inclination amount Δ of the mast 10 is determined using data corresponding to the weight W of each package 16 shown in FIG. 4 (steps 7 and 8).

Since the arithmetic control unit 27 of the controller 3 always recognizes the current position of the vehicle body 2 based on the detection output of the traveling encoder 6 (step 9), the loading / unloading position adjusting means 44 calculates the inclination amount. With reference to the data of the tilt amount Δ obtained by the means 43, the traveling motor 23 is moved so that the vehicle body 2 reaches a position in front of the mast 10 from the reference position at a predetermined distance L from the rack 18 by the tilt amount Δ. Is driven again (step 10), and the traveling output is stopped at the time when the vehicle reaches the position just before the reference position by the amount of inclination Δ of the mast 10 from the reference position (step 11). (Steps 12 and 13).

Next, the controller 3 controls the lifting motor 2
2 to lower the fork 11 slowly and
The pallet 15 on which 6 is placed is lowered onto the shelf 19 of the rack 18. In this case, since the distance to the rack 18 has already been adjusted in consideration of the inclination amount Δ of the mast 10, even when the inclination amount Δ of the mast 10 is large, the luggage 16 The luggage 1 is always kept at an appropriate position without being placed behind the specified position.
6 is dropped. When the transport of the load 16 is completed in this way, the controller 3 controls the traveling drive device 8 to move the vehicle body 2 backward for the next operation.

In the above description, the case where the package 16 is transported and placed on the shelf 19 of the rack 18 has been described. The basic operation is the same for the case of transporting to a destination. However, when carrying out this unloading operation, since the luggage 16 is not yet placed on the fork 11, the mast 10 is slightly inclined backward, and the amount of inclination becomes a negative value (-Δ). Therefore, the vehicle body 2 is moved from the rack 18 by a predetermined distance L
When the vehicle reaches a position that is extra close to the rack 18 by Δ from the reference position that is just away from the reference position, the forward traveling is stopped.

In the above embodiment, the mast 10
The travel stop position of the vehicle body 2 is adjusted according to the inclination amount Δ of the fork 1, but the fork 1 is adjusted according to the inclination amount Δ of the mast 10.
The reach position of No. 1 may be adjusted.

FIG. 8 shows an unmanned forklift.
As shown in FIG. 5, there is a reach type in which the mast 51 moves in the front-rear direction along the reach rail 52 by driving the reach carriage 50. The present invention is also applicable to such a reach type unmanned forklift.

That is, when the present invention is applied to the reach type unmanned forklift, it is necessary to detect the reach amount of the mast 51. Therefore, for example, the magnetic scale 55 and the magnetic sensor 56 Is provided. Then, in addition to the control system having the configuration shown in FIG. 2, the detection output of the magnetic sensor 56 is taken into the controller 3, and the reach position of the fork 11 is adjusted according to the tilt amount Δ by driving the reach cylinder by the hydraulic motor. To do. The specific control operation is shown in the flowchart of FIG.

In the flowchart of FIG. 9, steps 21 to 28 are basically the same as the operations based on the flowchart shown in FIG. 6, and calculate the weight of the load 16 in accordance with the magnitude of the vertical movement of the fork 11. , The inclination amount Δ of the mast 51 is obtained from the weight. When the inclination amount Δ of the mast 51 is determined in this manner, the loading / unloading position adjusting means 4
4, the appropriate reach moving distance is calculated (step 29). Then, while driving the hydraulic motor (not shown) (step 30), the detection output of the magnetic sensor 56 of the reach amount detector 54 is fetched (step 31), and the current reach position of the mast is determined by the appropriate When the reach movement distance is reached (step 32), the hydraulic motor is stopped (step 33).

In this manner, even in the reach type unmanned forklift, the load 16 can be loaded and unloaded at an appropriate position. In addition, when the packages 16 are stacked, they can be stacked vertically, so that the stacked packages 16 can be prevented from falling over.

In the above embodiment, the lifting encoder 7
By detecting the number of pulses in the unit time T, the ascending / descending speed V of the load 16 is detected. However, by measuring the time during which the fork 11 moves a predetermined distance L,
It is also possible to detect the elevating speed V. In such a case, instead of using the elevating encoder 7 as described above, a pair of upper and lower limit switches, a photocoupler, and the like are attached to the mast 10 at a fixed distance L to constitute the speed detecting means. be able to.

[0046]

According to the present invention, the following effects can be obtained. (1) In an unmanned forklift, the magnitude of the load is calculated from the difference in the lifting speed depending on the magnitude of the load, the amount of mast inclination is calculated based on the calculation result, and the vehicle body is automatically adjusted according to the amount of inclination. Since the traveling stop position or the reach position of the fork is adjusted, the loading / unloading operation of the luggage can be always performed in an appropriate state. In addition, since the stop position of the vehicle body can be reliably adjusted without particularly providing a conventional rack beam sensor, cost can be reduced.

(2) In the reach type unmanned forklift, the load can be loaded and unloaded at an appropriate position. Further, since the reach stroke can be adjusted according to the magnitude of the load, it is possible to eliminate the disadvantage that the reach stroke is insufficient at the time of loading. further,
When stacking the loads, the loads can be stacked vertically, so that the stacked loads can be prevented from tipping over, and the safety can be improved.

(3) In addition, if an existing elevation encoder provided for detecting the elevation height of a fork carrying a load is used as a part of the speed detection means, the load can be directly detected. It is not necessary to provide a pressure sensor or the like, which can avoid an unnecessary increase in cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram when loading and unloading luggage with an unmanned forklift according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically showing a control system for performing operation control in the unmanned forklift according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between the weight of a load placed on a fork and a fork elevating speed at that time in the embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a fork height and a mast inclination amount according to the weight of luggage in the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a mast inclination amount and a lifting height according to the weight of luggage.

FIG. 6 is a flowchart of a control operation for performing an appropriate loading / unloading operation according to the weight of a load in the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of a pulse train output from a lifting encoder in the embodiment of the present invention.

FIG. 8 is a perspective view showing a reach mechanism portion of a reach type unmanned forklift according to the embodiment of the present invention.

FIG. 9 is a flowchart of a control operation for performing a loading / unloading operation with an appropriate reach amount according to the weight of a load in the embodiment of the present invention.

FIG. 10 is an explanatory diagram in the case of loading and unloading luggage in a conventional unmanned forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unmanned forklift 2 Body 3 Controller 6 Travel encoder 7 Elevation encoder 10 Mast 11 Fork 16 Luggage 26 Memory 27 Calculation control part 41 Speed detection means 42 Load calculation means 43 Inclination amount calculation means 44 Loading / unloading position adjustment means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Eiichi Hekaku 2-1-1 Higashikami-shi, Nagaokakyo-shi, Kyoto Japan F-term (reference) 3F333 AA02 AB13 BA11 FA04 FA11 FA26 FD03 FD06 FD20 FE04 FE05 FE09

Claims (3)

[Claims] 1. A speed detecting means for detecting a lifting speed of a load, a load calculating means for calculating a weight of the load based on a magnitude of the lifting speed of the load detected by the speed detecting means, Means for calculating the mast inclination corresponding to the weight of the luggage calculated by the means; and stopping the running of the vehicle body according to the mast inclination obtained by the inclination calculation means. An unloading position adjusting means for adjusting at least one of the position and the reach position of the fork. 2. A reach-type mast in which a mast moves in the front-rear direction, wherein a speed detecting means for detecting an ascending / descending speed of the load, and a magnitude of the ascending / descending speed of the load detected by the speed detecting means. Load calculating means for calculating the weight of the luggage based on the load, inclination calculating means for obtaining the amount of mast tilt corresponding to the load calculated by the load calculating means, An unloading position adjusting means for adjusting a fork reach position in accordance with a mast inclination amount obtained by the means. 3. The unmanned forklift according to claim 1, wherein the speed detecting means includes a lifting encoder that generates a pulse train of a number corresponding to a lifting distance of the fork.