JPH08169698A - Load scooping and stacking method by unmanned forklift - Google Patents

Abstract

PURPOSE: To certainly and quickly sense the actual target level including dislocation at the time of load scooping and stacking. CONSTITUTION: At the time of scooping a load, the fork of an unmanned forklift 1 is descended from a place good over a planned target level, and a hole H provided in a pallet is sensed by an objective sensor 12 which senses the object existing ahead. At the time of loading object, the fork is elevated from a place good below the planned target level, and the lever where the sensor 12 does not sense a plate 22b of a rack 2 any more is judged as the actual target level.

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 unloading a load, and more particularly to a scooping and loading method capable of quickly and reliably detecting a target height for moving a fork.

[0002]

2. Description of the Related Art In factories, warehouses, and the like, unmanned forklifts have been put into practical use, which autonomously travel on the floor surface and automatically load and unload goods to convey articles. The unmanned forklift truck travels to a preset unloading position and lifts and reciprocates the fork to unload the cargo.
The target height of the fork, that is, the height of each shelf on which the load is placed, the height of the truck bed, and the like are predetermined, and the fork is stopped according to the target height. An objective sensor for detecting the presence of an article in front of the fork is attached to the tip of the fork. If an obstacle is detected in front of the fork, the forward movement of the fork is stopped for safety. .

[0003]

The fact that an obstacle is detected in front of the fork means that the target height deviates from a predetermined height unless the stop position of the unmanned forklift is incorrect. . The difference in target height is
For example, the wheels of the unmanned forklift may be worn, the floor surface may be uneven, and the truck bed may sink due to the load amount. In such a case, the controller of the unmanned forklift has to move the fork up and down within an appropriate range and search for the pallet hole and the space in front by the objective sensor at the tip of the fork, and it takes time to detect the actual target height. Was there.

Therefore, an object of the present invention is to provide a hoisting method and a hoisting method capable of reliably and promptly detecting a target height at which a fork should be advanced when an unmanned forklift truck is unloaded.

[0005]

In order to achieve the above object, the invention according to claim 1 is mounted at the tip of a fork and has an almost constant height by an objective sensor for detecting the presence or absence of an object in front of the fork. In an unmanned forklift that detects a certain target height for loading and unloading, the process of detecting the target height with an objective sensor while lowering the fork from a height sufficiently higher than the target height, and moving the fork forward at the detected height A method of picking and picking up by an unmanned forklift was configured, including the process of making.

According to a second aspect of the present invention, an unmanned vehicle mounted on the tip of a fork and detecting an object in front of the fork to detect a target height at a substantially constant height for unloading. In a forklift, an unmanned forklift loading method including a process of detecting a target height with an objective sensor while raising the fork from a height sufficiently lower than the target height and a process of advancing the fork at the detected height. Configured.

According to a third aspect of the present invention, in the process of advancing the fork, the object sensor does not detect an object in a region where an obstacle behind a target pallet mounting position can be detected. An unmanned forklift picking method according to claim 1 and an unmanned forklift loading method according to claim 2 are configured.

[0008]

Since the present invention has the above-mentioned structure, it has the following effects.

In the method for picking up an unmanned forklift according to the present invention, when the unmanned forklift picks up a fork, the fork is lowered from a height which is sufficiently higher than a target height which is substantially constant. Therefore, the objective height can be detected by the objective sensor during the descent. When the target height is detected, the fork is advanced at that height and the material is picked up.

In the loading method by the unmanned forklift according to the second aspect of the present invention, when the unmanned forklift performs loading, the fork is lifted from a height which is sufficiently lower than the target height which is substantially constant. Therefore, the objective height can be detected by the objective sensor during the ascent. When the target height is detected, the fork is advanced at that height and loading is performed.

In the loading and unloading method by the unmanned forklift according to the third aspect of the present invention, the objective sensor can detect the obstacle behind the target pallet mounting position in the process of moving the fork forward. Object detection is not performed in such areas.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below.

FIG. 1 is a side view showing an example of an unmanned forklift to which the unmanned forklift loading and unloading method according to the present invention can be applied, and FIG. 2 is a control structure of the unmanned forklift shown in FIG. 3 is a block diagram showing a main part of FIG.

In FIG. 1, the unmanned forklift 1 is equipped with a control device as shown in FIG. Based on the traveling motor 4
By controlling the vehicle, the vehicle autonomously travels on the floor surface F, and the fork lift motor 5 and the fork slide motor 6 are operated.
Is controlled to automatically load and unload the load from the shelf 2. Loading and unloading of forks 11 provided on the unmanned forklift 1
Made by. The fork 11 can be moved up and down with respect to the main body of the unmanned forklift 1 by operating the fork lift motor 5, and can be moved forward and backward in the lateral direction in the figure by the fork slide motor 6. For the sake of explanation, the right direction in the figure will be referred to as the front direction.

The shelf 2 includes a plurality of shelf plates 22 protruding from the wall K.
Consists of The load W placed on the pallet P is placed on the shelf plate 22. The pallet P is provided with two pallet holes H, and the pair of forks 11 are respectively inserted into the pallets P so that the pallets P are held by the forks 11 and the loads are unloaded.

An objective sensor 12 is provided at each tip of the pair of forks 11. The objective sensor 12 is
An object in front of the fork 11 is detected and the presence or absence of the object is transmitted to the control unit 3. The detection range R of the objective sensor 12 is not so long, and the control unit 3 causes the detection range R of the objective sensor 12 to include the load W, the pallet P, and the shelf board 22 when the fork 11 is moved up and down. The unmanned forklift truck 1 is stopped at the loading / unloading position as shown in (1) to perform the unloading work.

The fork lift motor 5 is provided with an encoder 7, and by detecting the rotation of the fork lift motor 5, the control section 3 can know the height of the fork 11. The target height storage unit 8 stores a plurality of target heights such as the height of the shelf 22 to be loaded and unloaded and the height of the truck bed, and the transfer instruction data transmitted from the host computer is stored in the target height storage unit 8. The target height of the matching shelf plate 22 or the like can be read and the height can be known.

Next, the operation of this embodiment will be described.

First, the time of picking and picking will be described. At the time of unloading, the control unit 3 causes the unmanned forklift 1 to arrive at the unloading position and then raises the fork 11 to the height indicated by 11a. This height is sufficiently higher than the target height read from the target height storage unit 8 that matches the conveyance instruction data currently being processed. That is, the shelf board 22 for the purpose of carrying out scooping even if the possible deviation in the height direction is taken into consideration.
The height is always higher than the height of the pallet hole H of the pallet Pa of the load Wa loaded on a. The height of the fork 11 is detected by the encoder 7.

Next, the fork 11a is lowered. While lowering, the objective sensor 12 is operated. Objective sensor 1
2 detects the parts other than the pallet hole H of the load W and the pallet P. When the descent is further continued, the tip of the fork 11 is located in front of the pallet hole H and the object cannot be detected. This height may deviate from the target height read from the target height storage unit 8, but the control unit 3 recognizes this height as the actual target height and Stops the lowering of the fork 11 with. The fork 11 at the actual target height is shown at 11b. The target height is also determined in consideration of the thickness of the fork 11.

If the objective sensor 12 does not detect the load W, which is the object of scooping, when the fork 11a is lowered.
Since it is considered that the unmanned forklift 1 is stopped at an incorrect position or that the load W is not placed on the target shelf 22 or the like, the control unit 3 stops the loading / unloading work and issues an alarm. Emit.

When the actual target height is normally detected and the lowering is stopped, the controller 3 advances the fork 11b.
The fork 11b can be advanced by sliding the fork 11b by the operation of the fork slide motor 6 and traveling the unmanned forklift 1 main body by the traveling motor 4. The fork 11b is moved forward by a certain distance, and when it reaches the position of 11c, the forward movement is stopped, the fork lifting motor 5 raises the fork 11c a little to scoop the load W onto the fork 11c, and then it is retracted. This completes the picking.

When the fork 11b is moved forward, the objective sensor 1 is moved after the fork 11b is moved to a position where an obstacle behind the pallet mounting position can be detected.
Stop the operation of 2. This is to prevent the objective sensor 12 from detecting the wall K. Until then, the objective sensor 12 is operated in order to prevent the collision with the front surface of the pallet Pa or the like due to the positional deviation. The pallet mounting position is a position (area) where the pallet P is currently mounted, or a position (area) where the pallet P should be mounted in the loading process described later. The control unit 3 stores in advance the position of the obstacle behind the pallet mounting position.

According to the above-mentioned hoisting and picking method, the fork 1 is moved from a height sufficiently higher than the intended height of the planned height.
By lowering 1, it is possible to reliably and quickly detect the actual target height including the deviation, and therefore it is possible to accurately carry out the scooping work in a short time.

Further, when the object Wa cannot detect the load Wa at the height at which the object sensor 12 starts to descend, it is determined that there is some abnormality, so that the abnormality can be surely confirmed at an early stage.

Next, the operation during loading will be described. At the time of loading, the unmanned forklift 1 holds and carries the load Wb placed on the pallet Pb on the fork 11. The control unit 3 causes the unmanned forklift 1 to travel to the loading / unloading position, and the fork 11 to have a height sufficiently lower than the target height, that is, below the target shelf board 22b.
The height is raised to 11d.

Then, when the fork 11d is raised, the objective sensor 12 detects the shelf plate 22b. Shelf 22
Since the thickness of b is stored in the control unit 3 in advance, it is possible to determine whether or not the shelf plate 22b is detected by detecting the distance by which the fork 11d is raised by the encoder 7.

When it is determined that the shelf plate 22b is detected, the fork 11d is elevated above the shelf plate 22b. Further, the height considering the thickness of the fork 11 and the thickness of the pallet P is the actual target height. Control unit 3 is fork 1
The ascent of 1 is stopped at the target height 11e, and the fork 11e is advanced to the position 11f. Then, the fork 11f is lowered slightly, the pallet P is placed on the shelf plate 22b, and when no load is detected on the fork 11, the lowering is stopped and the fork 11 is retracted. This completes loading. When the fork 11b is advanced, the operation of the objective sensor 12 is stopped after the fork 11b has advanced to a position where an obstacle behind the pallet mounting position can be detected, as in the case of picking. .

If another load has already been placed on the shelf plate 22b, the objective sensor 12 is mounted on the shelf plate 22b.
In addition to the thickness of the pallet P, the thickness of the pallet P is also detected, so that the controller 3 can know the occurrence of an abnormality and issue an alarm.

According to the above loading method, the fork 11 is lifted from a height sufficiently lower than the intended height, and the objective sensor 12 detects the intended shelf plate 22b to detect the actual purpose, including the deviation. Since the height is detected, loading work can be performed quickly and reliably.

Further, especially when the loading place is a shelf, there is an advantage that the vertical clearance can be minimized. Since the target height is detected by raising the fork 11 from below the shelf plate 22b, the fork 11 will not be raised more than necessary. Therefore, for example, when loading is always carried out from a fixed height, a large clearance must be taken between the upper shelf plate 22c and the upper surface of the load W in order to prevent collision, in consideration of the deviation. Compared with the above, the clearance is minimized, so that the storage efficiency of the shelf can be improved.

FIG. 3 is a view for explaining the processes of scooping and loading with the bed of the truck T according to the same embodiment.

A load W placed on a pallet P is placed on the loading platform of the truck T. The load W is placed directly or on the load platform. The target height storage unit 8 stores the height of the loading platform and the height of the upper surface of the load W placed on the loading platform.

The loading platform of the truck T sinks due to the weight of the loading W, so that a deviation occurs between the previously stored target height and the actual target height. Therefore, scooping and loading are performed in the same process as the above process.

At the time of loading and unloading, the process is the same as that shown in FIG. 1, and the fork 11 is lowered from the height L to move the pallet Pc.
The pallet hole H is detected and the fork 11 is moved forward to carry out scooping.

At the time of loading, not the shelf 22 is detected but the bed or the load W is detected, so that the conditions for detecting the target height are slightly different. Position the fork 11 at a height L sufficiently lower than the intended height and raise it to
If there is no obstacle in front, you can judge it as the target height,
For example, when the load Wd is already placed in spite of receiving the transport instruction to load the load We on the load We, the pallet hole H of the pallet Pd may be detected. is there.

Therefore, the control unit 3 further extends the fork 11 by a distance longer than the vertical size of the pallet hole H stored in the control unit 3 after the object is no longer detected while the fork 11 is being raised. To raise. If the load Wd is placed, the objective sensor 12 will detect the object forward again. In this case, it is determined to be abnormal. If no object is detected, it is normal and stops climbing before loading. Unlike the shelves, vertical clearance does not matter.

According to the above-described loading and unloading method, even if the loading platform of the truck T sinks, the control unit 3 knows the actual target height and can unload the loading.

The embodiment of the present invention has been described above.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be appropriately modified within the scope of the gist of the present invention.

[0040]

As described above, according to the method of picking and picking up by the unmanned forklift according to the first aspect, the objective sensor is used to lower the target height while lowering the fork from a height which is sufficiently higher than the target height of substantially constant height. Therefore, the actual target height including the deviation can be detected reliably and promptly, and therefore the work of picking and picking can be performed accurately and in a short time.

According to the loading method by the unmanned forklift according to the second aspect, the fork is raised from a height sufficiently lower than the target height of the spike and the actual target height including the deviation by the objective sensor. Is detected, the loading operation can be performed quickly and reliably.

According to the method of scooping and loading by the unmanned forklift according to the third aspect, in the process of advancing the fork, in the region where the objective sensor can detect the obstacle behind the intended pallet mounting position. Since the object is not detected by the objective sensor, it is possible to prevent erroneous detection of an object such as a wall behind the pallet.

[Brief description of drawings]

FIG. 1 is a side view showing an example of an unmanned forklift capable of implementing an embodiment of a method for picking up and loading a method by an unmanned forklift according to the present invention.

FIG. 2 is a block diagram showing a main part of a control structure of the unmanned forklift truck of FIG. 1.

FIG. 3 is a diagram illustrating a process of scooping and loading with a truck according to the embodiment of FIG.

[Explanation of symbols]

 1 Forklift 11 Fork 12 Objective Sensor 2 Shelf 22 Shelf P P Pallet H Pallet Hole W Load

Claims (3)

[Claims] 1. An unmanned forklift that is mounted on the tip of a fork and detects the presence or absence of an object in front of the fork to detect the target height at a substantially constant height for loading and unloading, and An unmanned forklift picking method including a step of lowering a fork from a sufficiently high height to detect a target height by an objective sensor and a step of advancing the fork at the detected height. 2. An unmanned forklift that is mounted on the tip of a fork and detects the presence or absence of an object in front of the fork to detect a target height at a substantially constant height for loading and unloading. An unmanned forklift loading method including a step of detecting a target height by an objective sensor while raising a fork from a sufficiently low height, and a step of advancing the fork at the detected height. 3. The unmanned forklift load according to claim 1, wherein in the process of advancing the fork, no object detection is performed in a region where the objective sensor can detect an obstacle behind a target pallet mounting position. The method of scooping and the method of loading by an unmanned forklift according to claim 2.