JPS61273498A - Unmanned cart guide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to a device for guiding an unmanned transport vehicle carrying a load on the front part by means of lateral guide surfaces.

BACKGROUND OF THE INVENTION In recent years, unmanned forklifts and automated guided vehicles have been developed for the purpose of saving labor in on-site transportation vehicles such as forklift trucks (hereinafter referred to as forklifts).

In order to guide such an unmanned transportation vehicle, the present applicant first proposed a guide member installed on the ground (including the side wall of the container, etc.) and a guide member installed on the vehicle and located on the side of the vehicle. The present invention has proposed a guidance device that includes a guide surface detection means for detecting the guide surface of the guide member and causes a vehicle to travel along the guide surface.

Problems to be Solved by the Invention Although such a guide surface following type guidance device can achieve high guidance precision in terms of straightness, etc., there may be a portion in the middle of the guide surface where the distance to the vehicle suddenly changes for some reason. (steps, etc.) may occur.

For example, in order to sequentially load cargo from a platform into a container, the side wall of the container is retrofitted to a fixed position guide wall installed on the platform, and an unmanned forklift or other vehicle runs along the guide surface formed by the guide wall and the container side wall. When trying to run an unmanned vehicle,
An example of this is a case where a difference in level occurs between the container side wall and the guide wall due to a shift in the stop position of the container. If there is a sudden change in the distance from the vehicle in the middle of the guide surface, it becomes difficult to guide the vehicle properly because there are limits to the detection ability of the guide surface detection means and the ability to follow the vehicle. In this case, it is necessary to accurately position the container by turning the trailer many times until the container side wall is aligned with the guide wall, which requires a considerable amount of time.

Therefore, it is conceivable to gradually eliminate the discrepancy such as a step that occurs in the middle of the guide surface by using a relatively long inclined portion such as a rotating wall. If this is done, the vehicle will be able to follow the guide surface and all problems will seem to be resolved.

However, the distance between the cargo at the front of the vehicle and the guide surface is usually small, and the guide surface detection means of the vehicle is located behind the cargo, so the guide surface detection means does not detect the inclined portion of the guide surface. Another problem arises in that the cargo comes into contact with that part, and unless this problem is also resolved, the problem as a whole will not be resolved.

Means for Solving the Problems The present invention has been made in order to solve the above-mentioned problems of a device that guides an automatic guided vehicle with a load loaded on the front part by means of lateral guide surfaces. The guidance device according to the present invention includes the following requirements.

(a) A movable guide member that is connected to an end of a fixed guide member provided on the ground so as to be rotatable around a vertical line, and forms the guide surface together with the fixed guide member; (b) A movable guide member that is provided on the unmanned transportation vehicle. According to the angle detected by the angle detection means (C1 angle detection means (d) for detecting the rotation angle of the movable guide member with respect to the fixed guide member) Load position control means for changing the lateral position of the load to avoid contact between the load and the guide surface of the movable guide member. If the forklift is equipped with a sight shift attachment that side-shifts the fork and the load in the left-right direction of the vehicle, the load position control means is configured to control the sight shift attachment and the side shift amount of the attachment using the angle detection means. A preferred embodiment includes a side shift amount detection means that determines the amount according to the detected value.

Effects of the Invention In the guidance device configured as described above, the movable guide member that can rotate around a vertical line eliminates discontinuous portions such as the step and staggered portions where the vehicle cannot maintain followability as they are. The retrofitting of the container can accommodate displacements, for example by connecting the free end of the movable guide member to the side wall of the container.

Moreover, depending on the rotation angle of the movable guide member relative to the fixed guide member, the lateral position of the cargo is changed to avoid contact between the cargo and the guide surface of the movable guide member. Regardless of the inclination of the guide member, the vehicle's cargo does not come into contact with the guide surface of the movable guide member, making it possible to guide the vehicle along the angled guide surface while protecting the cargo. It will become.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 and FIG. 2 show an example of a case where the present invention is applied to a guidance device for a counterbalance type forklift. In the figure, 2 is the vehicle body, and the front wheels are the drive wheels 4.
, the rear wheels are used as steering wheels 6. The vehicle body 2 is provided with a balance weight 8 at the rear and a head guard 10 above. At the front of the vehicle body 2, as is well known, cargo handling devices including a fork 12, an outer mast 14, and an inner mast 16 are provided. The inner mast 16 is guided by the outer mast 14 in the vertical direction via rollers, and the inner mast 16 further guides the lift bracket 18. A finger bar 20 is attached to the lift bracket 18 via a side shift attachment 19, and a pair of forks 12 are attached to the finger bar 20. When the inner mast 16 is raised by the operation of the lift cylinder 22, the lift bracket 18, finger bar 20, and fork 12 are raised integrally by a chain (not shown).

The lower end of the outer mast 14 is attached to the vehicle body 2 so as to be rotatable around one axis, and the operation of the tilt cylinder 24 causes the cargo handling equipment including the outer mast 14 to be tilted forward or backward. Further, by the operation of the side shift cylinder 26, the finger bar 20 and the fork 12 are side-shifted relative to the lift bracket 18 in the left-right direction of the vehicle body 2.

This forklift 28 can be operated manned by a driver, but it can also be operated unmanned by being guided using a guide wall 30 as shown in FIG.

Lateral displacement sensors 32 and 34 are attached to the sides of the vehicle body 2 as guide surface detection means, which contact the guide wall 30 to detect the distance and traveling attitude of the vehicle body 2 with respect to the guide wall 30. The lateral displacement sensor 32 includes a box 36 fixed to the vehicle body 2, as shown in FIG. 3, and an entry/exit member 38 is provided within the box 36. The entrance/exit member 3 includes a longitudinal main body 40, crossbars 42 and 43 fixed at right angles to one end and the upper surface of the intermediate portion of the main body 40, respectively, and fixed to the lower surface of the intermediate portion of the main body 40. a slider 44;
is movably supported by a guide rail 45 fixed to the box 32 in a direction perpendicular to a wall surface 46 of the guide wall 30 (hereinafter referred to as the guide wall surface 46 since this wall surface 46 functions as a guide surface). This entrance/exit member 38 is moved by the guide wall surface 46 by two springs 47.
It is always biased toward the side, and the amount of movement in and out of the box 36 is detected by a linear potentiometer 48. A contact plate 52 having a U-shaped cross section is attached to the distal end of the main body 40 of the entry/exit member 38 so as to be rotatable around the axis of a vertical shaft 50 at an intermediate portion.

The contact plate 52 is held in a neutral position, normally perpendicular to the body 40, by two symmetrically arranged springs 54. Both ends of the contact plate 52 are
Each of them is curved in a direction away from the guide wall surface 46, and as shown in FIG.
is rotatably attached, and if there is an obstacle such as a protrusion on the guide wall surface 46, the contact plate 52 rotates around the axis of the shaft 50 to help overcome it. Note that if a crawler belt (orbital belt) made of a flexible material such as rubber is wound around these rollers 56 and the crawler belt rotates in contact with the guide wall surface 46,
Rubbing with the guide wall surface 46 is avoided, improving followability and durability.

The other lateral displacement sensor 34 has a similar configuration, and the output signals of the linear potentiometers 48 of both lateral displacement sensors 32 and 34 control the vehicle body 2 and the guide wall surface 46.
The distance between the load W supported by the pair of forks 12 and the guide wall surface 46 is detected. Also, due to the difference in the output of both linear potentiometers, the car body
The inclination (traveling posture) of the vehicle around the perpendicular line with respect to the guide wall surface 46 is detected.

The forklift 28 as described above is shown in FIGS. 5 and 6.
As shown in the figure, it is used to sequentially load cargo W sent by a chain conveyor 62 installed on a platform 60 into a container 66 retrofitted to the platform 60 via a span plate 64. be. The chain conveyor 62 is buried in the platform 60 and its chains slightly protrude from the floor surface of the platform 60, so that the forklift 28 can run across the chain conveyor 62.

The platform 60 is provided with the guide wall 30, which is a structure in which a fixed guide wall 68 functioning as a fixed guide member and a movable guide wall 70 functioning as a movable guide member are connected. It is. These guide walls 68 and 70 are both band-shaped plate members, and extend in the horizontal direction at the height of the lateral displacement sensors 32 and 34 in a posture perpendicular to the platform 60. The fixed guide wall 68 is installed in a fixed position on the platform 60, while the movable guide wall 70 has an axis 72 perpendicular to one end of the fixed guide wall 68.
The free end portion thereof is connected to the rear end of the side wall 74 of the container 66, and forms the guide wall surface 46 together with the fixed guide wall 68. Also,
After the forklift 28 enters the container 66, the wall surface of the container side wall 74 that is continuous with the movable guide wall 70 functions as a guide surface for guiding the forklift 28.

As is clear from FIGS. 7 and 8, the movable guide wall 70 is integrally provided with the vertical shaft 72 at its base end, and the lower portion of the shaft 72 is a small diameter portion 76. By fitting this small diameter portion 76 into a cylindrical post 78 erected on the platform 60, the shaft 72
It is rotatably supported around the axis of. The front end of the fixed guide wall 68 abuts this shaft 72 very closely.

Further, a small diameter portion 80 is integrally formed in the upper portion of the shaft 72, and a rotary potentiometer 84 is connected to this small diameter portion 80 via a coupling 82, and its main body is attached to the fixed guide wall 68 by a bracket 86. Fixed. This rotary potentiometer 84 is connected to the movable guide wall 70
The fixed guide wall 68 and the movable guide wall 7
As is well known, the angles in the clockwise (clockwise) and counterclockwise (counterclockwise) directions with respect to a reference position that is in a straight line with 0 are detected using the change in electrical resistance value that corresponds to the rotation angle. It is something.

The rotary potentiometer 84 is connected to the ground station 88 shown in FIG.
It is connected via an I10 interface 92 to a microprocessor (CPU: central processing unit) 90 shown in FIG. The amount of side shift is determined.

That is, a memory 94 is connected to the CPU 90, and this memory 94 stores in advance a plurality of types of shift data representing stepwise different side shift amounts according to the angle signal of the rotary potentiometer 84. According to the angle signal from the rotary potentiometer 84, one of the shift data matching the angle signal is read out from the memory 94. In this example, CPU9
0 constitutes side shift amount determining means together with the memory 94.

As is clear from FIG. 1, the fixed guide wall 68 has four projectors 96, 98, 10 arranged in the front and back direction.
0 and 102 are fixed at positions away from the movement loci of the lateral displacement sensors 32 and 34, respectively, as shown in FIG.
/○ Connected to interface 92. On the other hand, a bracket 10 is attached to the side of the vehicle body 2 of the forklift 28.
4, the four light receivers 106, 108, 110 and 112 are fixed to the fixed guide wall 68 at positions where their optical axes can coincide with the four projectors, respectively, as shown in FIG. It is connected via an I10 interface 124 to an on-vehicle microprocessor (CPU) 120 provided in 28.

Emitters 96, 98, 100 and receivers 106, 108.1
Of the three sets with 10, one set is for transmitting information as to which side, left or right, the movable guide wall 70 is angled with respect to the fixed guide wall 68 by an optical ON/OFF signal, The remaining two sets are for transmitting shift data representing the side shift amount according to the angle of the movable guide wall 70 with respect to the fixed guide wall 68 by a combination of optical ON-OFF signals. In this case, 2
By combining a set of emitters and receivers, it is possible to transmit four different types of shift data.

The light emitter 102 and the light receiver 112 are for detecting that the three sets of light emitters and light receivers are aligned on the same optical axis, but the light emitters 96, 98, 1
In this example, the positions where 00 and the light receivers 106, 108, and 110 respectively coincide are the loading positions,
The light emitter 102 and the light receiver 112 are mounted on a forklift 28
It also serves as an optical sensor for detecting that insertion of the fork into the load W has been completed.

In addition, in FIG. 1, 114 is a drive motor that drives the drive wheels 4, and this drive motor 114 includes:
A travel distance sensor 116 is provided for calculating the rotation speed of the output shaft and detecting the travel distance of the forklift 28 from the loading position.
is also connected to the I10 interface 124 on the vehicle.

As mentioned above, the I10 interface 124 has a CPU
120 is connected with the memory 122, and the linear potentiometers 4 of the lateral displacement sensors 32 and 34
8 and various other sensors necessary for unmanned control of the forklift 28 are connected.

The I10 interface 124 further includes a travel control circuit 1.
40. Steering control circuit 142. A brake control circuit 144 and a cargo handling control circuit 146 are connected, the drive motor 114 that drives the drive shaft 4 is connected to the travel control circuit 140, and a steering control circuit 142 is connected to the drive motor 114 that drives the drive shaft 4.
A steering motor 150 that steers the steering wheel 6
is connected. In addition, the brake control circuit 144 includes:
An electromagnetic brake 152 that brakes the motor shaft of the drive motor 114 is connected, and an electromagnetic valve 156 that controls oil pressure to the hydraulic brake 154 that brakes each drive shaft 4 is also connected.

The cargo handling control circuit 146 includes the lift cylinder 22, the tilt cylinder 24 . A solenoid valve 158 that controls the supply of hydraulic pressure to the side shift cylinder 26 and the like is connected, and by controlling the operation of the solenoid valve 158, the cargo handling equipment 160 including the fork 12 and the lift bracket 18 is controlled. The operation will be controlled. Further, the CPU 120 processes operation signals of various sensors and switches including the aforementioned lateral displacement sensors 32, 34, etc. according to a program stored in advance in the memory 122, and performs operations such as steering, acceleration/deceleration, and stopping of the forklift 28. Automatically controls temporary standby, automatic transfer, etc.

Next, a program for unmanned guidance of the forklift 28 will be explained with reference to the flowchart shown in FIG.

First, as shown in FIG. 10 or 11, after the container 66 is retrofitted to the platform system 60, the free end of the movable guide wall 70 is connected to the rear end of the side wall 74 of the container 66. The container 66 is positioned so that its side wall 74 is located approximately on the extension line of the fixed guide wall 68. However, even if there is a deviation in the position of the container 66 with respect to the platform 60, the deviation will be caused by the movement of the movable guide wall 70.
It is absorbed by the rotation around the axis of the shaft 72.

The angle of the movable guide wall 70 with respect to the fixed guide wall 68 is detected in step S1 by the rotary potentiometer 84 shown in FIG.
Sent to PU90. Subsequently, step S2 is executed,
The CPU 90 selects optimal shift data from among the plurality of side shift data stored in the memory 94 according to the angle signal from the rotary potentiometer 84.

On the other hand, the forklift 28 is connected to the chain conveyor 62.
Until the load W is sent to the loading position, it is kept on standby at a standby position behind the loading position, but when a predetermined sensor detects that the load W has been sent to the loading position, It moves forward from the standby position toward the loading position, and inserts the fork 12 into the fork insertion groove of the load W or into the pallet.

The completion of the insertion means that the projector 1 shown in FIG.
It is detected by the light receiver 112 receiving the light from 02, and based on the detection signal of the light receiver 112, the C on the vehicle is detected.
The PUI 20 stops the drive motor 114, and operates the electromagnetic brake 152 and the hydraulic brake 154 to stop the forklift 2 at the loading position, which is the insertion completion position shown in FIG. At this time, the projectors 96, 98, 100 provided on the fixed guide wall 68 and the receivers 106, 108, 110 provided on the vehicle body 2 face each other, and in this state step S3 is executed,
ON/OFF by light from receiver 96, 98, 100
When the light receivers 106, 108, and 110 detect the signals, the angular direction data of the movable guide wall 70 and the side shift data selected by the CPU 90 on the ground are transmitted to the CPU 120 on the vehicle, and the shift data etc. are transmitted to the CPU 120 on the vehicle. The data is stored in the memory 122 at the time.

Furthermore, by executing step S5, the mileage sensor 116 is turned on, and in the subsequent step S6, it is determined whether the movable guide wall 70 is angled to the right or to the left Cζ with respect to the fixed guide wall 68. be judged.

If it is determined that the forklift 28 is angled to the right as shown in FIG.
The side shift cylinder 26 is operated in a state where the load W is lifted at the insertion completion position shown in FIG.
The forklift 2 and the cargo W are side-shifted to the right with respect to the lift bracket 18 and the like via the side shift attachment 19. In other words, the CPU 120 on the vehicle
Based on the shift data transmitted from the ground CPU 90 and stored in the memory 122, the shift data is converted into an actual side shift amount (command value), and the side shift is performed via the cargo handling control circuit 146 and the electromagnetic valve 158. By operating the cylinder 26, the load W is side-shifted from the origin, that is, the center position of the vehicle, by a command value to the right. This side shift amount is
Until the front side lateral displacement sensor 32 detects the movable guide wall 70, the front end corner of the cargo W and the movable guide wall 70
This is considered to be a necessary and sufficient amount of shift to avoid contact with the vehicle. Then, when the forklift 28 starts traveling and the lateral displacement sensor 32 detects the movable guide wall 70, resulting in an output difference between the rear lateral displacement sensor 34 and the linear potentiometer 48, the CPU 120 controls the steering control circuit. A steering motor 150 is actuated via 142 to steer the forklift 28 along the movable guide wall 70.

The traveling distance of the forklift 28 from the loading position is determined by the CPU 1 based on the signal from the traveling distance sensor 116.
20 is calculated, and it is determined in step S8 whether or not the mileage K has reached 1. The travel distance 1 is set as the distance required for both the lateral displacement sensors 32 and 34 of the forklift 28 to come into contact with the movable guide wall 70 in FIG. When the travel distance of the forklift 28 is reached, step S9 is executed, and the CPU 20 operates the side shift cylinder 26 by the same amount in the opposite direction to step S7, thereby shifting the load W from the right shift position to the left. Side shift and return to origin.

Further, in step S10, it is determined whether the travel distance of the forklift 28 has reached K IJ<K.

2 in this travel distance is the distance that the tip of the cargo W reaches the rear end of the container 66, but the forklift 28
If the cargo moves forward, the front end corner of the right side of the cargo W becomes the container 66.
To avoid this, when it is determined that the travel distance has reached 2, the load W is shifted to the fork 12 by actuating the side shift cylinder 26.
At the same time, step Sll is executed, in which the side is shifted to the left by the command value from the origin. This amount of side shift to the left is the same as the amount of side shift to the right in step S7, and is carried out by a command from the CPU 120 based on the side shift data stored in the memory 122. Further, in step Sj2, if it is determined that the traveling distance K has reached 3 and the forklift 28 is now aligned with the container side wall 74, step S13 is executed, and the cargo W is shifted from the left shift position. It is side-shifted to the right and returned to the origin. Thereafter, the forklift 28 is advanced along the container side wall 74 to the unloading position.

On the other hand, as shown in FIG. 11, when the movable guide wall 70 is angled to the left with respect to the fixed guide wall 68,
The determination result in step S6 is NO, and the forklift 28 moves toward the movable guide wall 70 while supporting the load W at the origin.
When it is determined in step 514 that the traveling distance has reached 2, the shift 1t (command value) corresponding to the side shift data stored in the memory 122 is started.
Step S15 of side-shifting the cargo W to the right is executed, thereby avoiding contact between the cargo W and the container side wall 74. Further, if it is determined in step 816 that the traveling distance has reached 3, the cargo W is side-shifted from the right shift position to the left and brought to the origin in step S17, and from then on, it is moved to the unloading position in this state. move forward until

In either case, after the forklift 28 reaches the unloading position and unloads the cargo W, the forklift 28 moves toward the container side wall 7 while keeping the fork 12 at the origin.
4. It retreats along the movable guide wall 70 and the fixed guide wall 68 and returns to the above-mentioned standby position. Thereafter, the same process is repeated, so that the cargo W is sequentially loaded from the platform 60 into the container 66. In addition,
Even when the cargo W is sequentially unloaded from the container 66, the control is essentially unchanged.

As is clear from the above description, the movable guide wall 70 is rotatably connected to the fixed guide wall 68, and the movable guide wall 70 is connected to the container side wall 74. There is no problem in retrofitting the platform 60 even if the position is shifted or uneven, and the cargo W is side-shifted according to the angle of the movable guide wall 70 to avoid contact between the movable guide wall 70 etc. and the cargo W. Therefore, the degree of freedom in guiding can be increased while protecting the cargo W.

In the embodiment described above, the ground CPU 90° memory 9
4 side shift amount determination means and side shift amount determination means 19 mainly consisting of side shift cylinder 26;
constituted a cargo position control means that controls the horizontal position of the cargo W according to the detected value of the rotary potentiometer 84, but the detected value of the rotary potentiometer 84 is processed into a digital quantity and used with light, etc. It is also possible to transmit the information to the on-vehicle CPU 120 using a transmission means, and have the on-vehicle CPU 120 determine the side shift amount.

Furthermore, instead of the rotation potentiometer 84 as the angle detection means, it is also possible to use, for example, a resolver that electromagnetically converts angular displacement into an electrical signal, or a low-resolution encoder that measures the rotation angle as a digital quantity.

In addition, the guide surface for unmanned guidance of the forklift 28 is not limited to a flat wall surface, but may be a roller roller on a guide rail having an arcuate cross section, for example, in the case of transportation work within a premises rather than loading/unloading work to a container. A curved surface may be used as a guide surface, such as when guiding while contacting the guide surface.

In addition, as a guide surface detection means for detecting the guide surface,
The lateral displacement sensors 32 and 34 are not limited to contact type sensors, but non-contact type sensors such as ultrasonic sensors may also be used.

Furthermore, although the present invention is suitably applied to a guidance device for an unmanned forklift, it can also be applied to other unmanned forklifts that are not equipped with a cargo handling device, as long as the vehicle is guided unmanned with a load placed on the front of the vehicle. It can be similarly applied to transport vehicles.

Although not described in detail, it goes without saying that the present invention can be practiced with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing an example in which the present invention is applied to a guidance device for an unmanned forklift, and FIG. 2 is a side view of the forklift. FIG. 3 is an enlarged sectional view showing a part of FIG. 1, and FIG.
It is IV-I'/sectional view in a figure. FIG. 5 is a plan view schematically showing an example of how the forklift is used, and FIG. 6 is a side view thereof. FIG. 7 is a side view showing the connecting portion between the fixed guide wall and the movable guide wall in FIG. 1, and FIG. 8 is a partial sectional view showing a part of FIG. 7. FIG. 9 is a block diagram schematically showing a control circuit for guiding the forklift shown in FIG. 1 and the like. 10 and 11 are plan views showing different guidance modes of the forklift, and FIG. 12 is a flowchart showing a guidance program for the forklift. 2: Vehicle body 12: Fork 14: Outer mast 16: Inner mast 18 Lift bracket 19: Side shift attachment 20: Finger bar 26: Side shift cylinder 28: Unmanned forklift (unmanned transport vehicle) 30 Guide wall 32. 34: Lateral displacement sensor ( Guide surface detection means) 44:
Linear potentiometer 46: Guide wall surface (guide surface) 60 Nibrat home 66: Container 68: Fixed guide wall (fixed guide member) 70: Movable guide wall (movable guide member) 72: Axis 74: Container side wall 8
4: Rotation potentiometer (angle detection means) 90.12
0: Microprocessor (CPU: central processing unit) 92, 124. : I10 interface 94.12
2: Memory 96.98, 100.102 = Emitter 106.108, 110, 112: Receiver Applicant Toyota Industries Corporation Toyota Motor Corporation

Claims (2)

[Claims] (1) A device that guides an unmanned transport vehicle with a load on the front part using a lateral guide surface, which is connected to the end of a fixed guide member installed on the ground so as to be rotatable around a vertical line, a movable guide member that constitutes the guide surface together with the fixed guide member; a guide surface detection means provided on the unmanned transportation vehicle to detect the guide surfaces of both the guide members; An angle detection means for detecting a rotation angle, and changing the position of the cargo in the left and right direction according to the angle detected by the angle detection means to avoid contact between the cargo and the guide surface of the movable guide member. An unmanned transport vehicle guidance device including a load position control means. (2) The unmanned transportation vehicle is a forklift truck having a fork on the front for loading a load and a side shift attachment for side shifting the fork and the load in the left-right direction of the vehicle, and the load position control means includes: 2. The apparatus according to claim 1, comprising: the side shift attachment; and side shift amount determining means for determining the side shift amount of the attachment in accordance with the detected value of the angle detecting means.