JPS61282299A - Unmanned forklift having contact-vibration detection function - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a forklift that can be driven unmanned along a predetermined track by loading a load onto a front cargo handling device having a fork.

In recent years, forklifts that can run unmanned, so-called unmanned forklifts, have been developed with the aim of reducing the labor involved in transporting loads and handling cargo using forklifts. This unmanned forklift is driven unmanned by a predetermined guidance system, and is equipped with an object detection sensor that detects obstacles in front of the truck. In many cases, there is a mechanism to stop it.

For example, in Japanese Utility Model Application No. 53-18775, an ultrasonic or light transmitter and receiver is provided at the tip of the fork, and ultrasonic waves are used to detect objects such as loads and obstacles in front without contact. A system has been disclosed that detects the object and stops the vehicle to avoid collision with the object. In addition, the fork has a contact type object detection sensor at the tip, and is equipped with a moving member such as a dog that is pushed back by contacting an object in front, and a proximity switch or limit switch that is operated by the moving member. A device that stops a vehicle based on the operation of this switch has also been known in the past.

It is equipped with a non-contact object detection sensor that uses ultrasonic waves, etc., as disclosed in the above-mentioned Japanese Utility Model Publication No. 18775/1983, or a dog that operates a limit switch or a proximity switch. If a contact-type object detection sensor is built into the tip of the fork, it is possible to accurately detect the presence of an obstacle, load, or other object in front of the vehicle in the traveling direction. However, it is ineffective in detecting objects on the sides or in front of the cargo, and must be said to be defenseless. In other words, in the case of a forklift, the load is usually wider than the fork spacing and protrudes to both sides, making it easy for the load to come into contact with objects on the side or in front of the side, such as pallet racks, luggage, container side walls, etc. In the event of contact, it is desirable to stop the forklift immediately, but the object detection sensor provided at the tip of the fork cannot detect this. For normal automated guided vehicles, it is not very difficult to install object detection sensors on the sides or in front of the front of the vehicle, but in the case of a forklift, the forks at the front of the vehicle are connected to the fork insertion groove of the cargo or the pallet. Because the fork is inserted into the fork and is inserted inside the left and right ends of the cargo, it is extremely difficult to provide a sensor at the tip of the fork to detect obstacles on the side or in front of the side.

In addition, when loading cylinders one after another into a container using an unmanned forklift, for example, it is desirable to load the front wall of the container, the frontmost load, and each load in close contact with each other in the front and back direction without any gaps. This will improve efficiency, but although the object detection sensor built into the fork tip described above can detect the front wall of the container or the cargo already loaded in front,
It is not possible to confirm whether the load on the fork has come into contact with the front wall of the container or the previous load and is pressed against it. Therefore, it is inevitable that a certain amount of space will be created between the front wall of the container, the cargo at the front, and each cargo.As a result, the cargo at the rear will not be able to fit into the container and the loading process will have to be repeated. There may be cases where this is not the case.

In order to solve the above-mentioned conventional problems, a forklift according to the present invention provides (a) a forklift of a cargo handling device or a member integral with the fork, the forklift being provided with (b) a travel distance detection device that detects the travel distance of the forklift from a reference position;
C) If the detection value of the travel distance detection device reaches a predetermined set value when the vibration detection device is activated, it is assumed that the cargo has contacted the stationary wall or load in front at the unloading position. Vehicle control that determines and stops the forklift and causes the cargo handling device to unload the load, and if the set value has not been reached, determines that the load has come into contact with an object on the way and stops the forklift in an emergency. means.

In the unmanned forklift truck configured in this way,
Based on the detection of vibrations generated in the fork, it is detected that the load on the fork has not only contacted an obstacle in front of the running path, but also has contacted an obstacle on the side or in front of the side. Since an emergency stop is performed based on this, it is possible to effectively avoid cargo collapse and damage, and the cargo can be protected against objects on the side or in front of the side without using a dedicated sensor. .

In addition, at the unloading position, the forklift is stopped and unloaded by detecting the vibration generated in the fork when the load on the fork comes into contact with the stationary wall in front (for example, the front wall of the container) or the load. For,
For example, when loading cargo into a container, it is possible to load the cargo in the front and back direction without any gaps, ensuring that a predetermined amount of cargo is loaded, and improving volumetric efficiency.

Based on the detected value of the travel distance detection device, it is determined whether the forklift is on the road when the vibration detection device is activated.
Since it is possible to tell whether the forklift is in the unloading position, it is possible to perform different operations depending on the position of the forklift.In other words, if it is on the way, it can perform an emergency stop, and if it is in the unloading position, it can perform two different operations: stopping and unloading, using a common vibration. This can be done based on the operation of the detection device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 and FIG. 2 show an example in which the present invention is applied to a counterbalance type forklift.

In the figure, reference numeral 2 denotes a vehicle body, with the front wheels serving as driving wheels 4 and the rear wheels serving 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 lifted bracket 18 via a side shift attachment 19, and a pair of forks 12 are attached to the finger bar 20.The inner mast 16 is raised by the operation of the lift cylinder 22. When the lift bracket 18.finger bar 2 is
0 and the fork 12 are raised together. 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. In addition, the side shift cylinder 26
, the finger bar 20 and the fork 12
is 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 to detect the distance and traveling attitude of the vehicle body 2 with respect to the guide wall 30 by contacting 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 entry/exit member 38 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 a slider fixed to the lower surface of the intermediate portion of the main body 40. 44, the slider 44 is connected to the wall surface 46 (
It is supported so as to be movable in a direction perpendicular to the guide wall surface 46 (hereinafter referred to as a guide wall surface 46). This in/out member 38 is always urged toward the guide wall surface 46 by two springs 47, and the amount of in/out from 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 roundly curved in a direction away from the guide wall surface 46, and as shown in FIG. A roller 56 is rotatably attached, and when an obstacle such as a convex part exists 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 is wound around both rollers 56 and the crawler belt rotates while contacting the guide wall surface 46, rubbing with the guide wall surface 46 can be avoided and the following can be avoided. Improves durability 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, and the distance between the guide wall 46 and the load W supported by the pair of forks 12 is detected.
The inclination around the perpendicular line with respect to the guide wall surface 46 is detected.

As is clear from FIG. 1, a vibration pickup 60 smaller than the thickness of each fork 12 is fixed to the inner surface of the tip of each of the pair of forks 12. These vibration big amplifiers 60 serve as a vibration detection device that detects the vibrations that occur in the fork 12 when the load W on the fork 12 comes into contact with an object in the running path, and detects the vibration that occurs in each fork 12. It functions as a converter that converts into electrical changes, and detects vibration displacement, velocity, or acceleration. For example, inductive pickup amplifiers that utilize the electromotive force generated in a coil that crosses a certain magnetic field, piezoelectric pickup amplifiers that use piezoelectric elements, variable resistance pickups that use resistance wire strain gauges, differential transformers, etc. Various types such as a variable inductance type pink-up can be used.

As is clear from FIG. 5, each vibration pink-up 60 includes an amplifier 64. A filter 66 and a comparator 68 are connected to each other, but in order to avoid complexity, only the connection circuit of one vibration pickup 60 is shown, and the illustration of the other one is omitted because it is completely the same. The output signal of vibration pickup 60 is amplified by amplifier 64 and guided to filter 66 . The filter 66 passes signals in a specific frequency band, that is, signals in a frequency band specific to vibrations that occur when the load W on the fork 12 comes into contact with an object on the track, but passes signals in other frequency bands, such as a forklift truck. Signals in the frequency band of vibrations associated with the running of the vehicle 28 are not allowed to pass through, and the signals that have passed through the filter 66 are supplied to the comparator 68 . A setting device 70 is connected to the comparator 68, and the setting device 7o outputs a reference signal of a predetermined constant level, that is, a signal of a magnitude that will be output when the cargo W comes into contact with an object in the runway. A signal is being input. The comparator 68 compares the magnitude of the detection signal passed through the filter 66 and the reference signal input from the setter 70, and outputs an output signal when the former is greater than or equal to the latter. And this comparator 6
8 is a microprocessor (central processing unit: CPU) 1
20. Memory 122 and I10 interface 124
It is connected via an I10 interface 124 to a CPU 120 of an on-vehicle microcomputer equipped with an on-vehicle microcomputer.

On the other hand, as is clear from FIG. 1, the drive wheels 6 are driven by a drive motor 126. The drive motors 1 and 26 are provided with a pulse pickup 128 that detects pulses generated in a number proportional to the number of rotations of the drive motors 1 and 26. This pulse pickup 128 has an I10 interface 124 as shown in FIG. It is connected to the CPU 120 via the CPU 120. C.P.
The UI 20 is configured to count the pulses supplied from the pulse pickup 128 using a pulse counter, and together with the pulse pickup 128 constitutes a travel distance detection device that detects the actual travel distance of the forklift 28 by replacing it with the number of pulses. .

In addition, the I10 interface 124 of this on-vehicle microcomputer
are connected to the linear potentiometers 48 of the lateral displacement sensors 32 and 34, and are also connected to various sensors, switches, and switches that are not shown but are necessary for unmanned control of the forklift 28. .

The I10 interface 124 further includes a travel control circuit 1.
40. Steering control circuit 142. Brake control circuit 144. Cargo handling control circuit 146 and alarm control circuit 148
The drive motor 126 for driving the drive wheels 4 is connected to the travel control circuit 140, and the steering motor 150 for steering the steering wheel 6 is connected to the steering control circuit 142. Further, an electromagnetic brake 152 for braking the motor shaft of the drive motor 126 is connected to the brake control circuit 144, and
An electromagnetic valve 156 that controls oil pressure to a hydraulic brake 154 that brakes each drive wheel 4 is connected. Furthermore, the cargo handling control circuit 146 includes the lift cylinders 22. A solenoid valve 158 is connected to control the supply of hydraulic pressure to the tilt cylinder 24, side shift cylinder 26, etc., and by controlling the operation of the solenoid valve 158, the fork 12, lift bracket 18, etc. The operation of the cargo handling device 160 will be controlled. Further, an alarm device 161 such as an alarm sound generating device such as a buzzer or a warning light blinking device is connected to the alarm control circuit 14B.
This alarm device 161 is provided in both or either one of the forklift 28 and the ground control station.

In the forklift truck 28 as described above, the lateral displacement sensors 32, 34 . The CPU 1 sends operating signals for various sensors and switches including the vibration pickup 60, etc.
20 performs processing according to a program stored in advance in the memory 122 to steer, accelerate/decelerate, stop, and temporarily stand by the forklift 28.

Automatically control automatic transfer, etc. In this embodiment, CPU1
20. Starting with an on-vehicle microcomputer equipped with a memory 122 and the like, a driving control circuit 140. Steering control circuit 142
．． A brake control circuit 144, a cargo handling control circuit 146, and the like constitute vehicle control means.

For example, as shown in FIGS. 6 and 7, such a forklift 28 carries a load W sent by a chain conveyor 164 installed on a platform 162 and is later attached to the platform 162 via a span plate 166. It is suitably used when sequentially loading containers into a container 168 (automatic container vanning). The chain conveyor 164 is embedded in the platform 162 so that a part of the chain slightly protrudes from the floor surface of the platform 162, and the forklift 28 can run across this chain conveyor 164. Further, the guide wall 30 is arranged to extend in a strip shape at the height of the lateral displacement sensors 32 and 34 in a direction perpendicular to the platform 162, and its front end is connected to the container 1.
68 is flush with the rear end of the side wall 170, and after the forklift 28 enters the container 168,
The wall surface of the container side wall 170 serves as a guide surface. The forklift 28 is first at the waiting station ST.
, the vehicle waits at the cargo receiving station ST, picks up the cargo W, enters the container 168, and unloads the cargo W at the unloading position. The number of pulses corresponding to the distance from the receiving station STI (or standby station ST) to just before the unloading position in the container 168 is stored as a set value, and the CPU 12Q uses the set value stored in the memory 122. and the pulse pickup 1
The position of the forklift 28 is determined by comparing the number of pulses, which is a detected value, supplied from the forklift 28. Moreover, each time the load W is carried into the container 168, the set value is determined by subtracting a value corresponding to the length of the load W in the front and back direction from the previous value, and the CPU 12
0 will be calculated and newly stored in the memory 122.

First, when the load W is sent to the load receiving station ST by the chain conveyor 164, the forklift 28 advances from the rear standby station ST to the load receiving station ST, and the fork 12 is inserted into the fork insertion groove of the load W or the pallet. Insert. Although not shown, completion of the insertion is detected by a touch switch provided on the fork 12, etc. at the rear of the cargo W.
Further, the load W is lifted and supported on the fork 12. This is step S1 in the flowchart shown in FIG. After Step S2 is executed and the pulse counter of the CPU 120 is reset, the forklift 28 carrying the cargo W is driven unmanned along the guide wall 30 and the container side wall 170 in Step S3. That is, the detection signals from the lateral displacement sensors 32 and 34 in contact with the guide wall 30 etc. are sent to the CPU 120 via the I10 interface 124, so that the CPU 120 determines whether the distance between the vehicle body 2 and the guide wall 30 etc. is within a predetermined range. The steering motor 1 is controlled via the steering control circuit 142 so that the running direction of the vehicle body 2 is maintained parallel to the guide wall 30, etc.
50 and guide wall 30 as well as container side wall 17
In other words, guidance is performed along 0.

In the process of such unmanned driving, the vibration pickup 6
0 detects the vibration occurring in the fork 12, but in step S4 it is determined whether the comparator 68 has issued an output signal, that is, whether the detection signal that has passed through the filter 66 is greater than the reference signal given by the setting device 70. Ru. If the determination result is YES, step S5 is executed, and it is determined whether the detected value, which is the number of pulses sent by the pulse pinkup 128 to the CPU 120, has reached the set value stored in the memory 122. . If it is determined that the target has not been reached, for some reason the fork 1
It is determined that the cargo W on the container 168 has come into contact with an object on the way, and for example, as shown in FIG. 172, and emergency stop step S6 is executed. That is, C
The PU 120 stops driving the drive motor 126 via the travel control circuit 140, and operates the electromagnetic brake 152 and the hydraulic brake 154 via the brake control circuit 144 to stop the forklift 28. Furthermore, by executing step S7, the alarm device 161 is activated via the alarm control circuit 148, and an alarm is issued by an alarm sound or an alarm light. In this way, contact with a member on the side or front side of the load W, which was a so-called blind spot in the past, is detected by vibration, and each step of emergency stop and alarm is executed. It is possible to avoid large shocks.

On the other hand, if it is determined in step S5 that the detection value by the pulse pin ablation 128 has reached the set value,
When the forklift 28 reaches the unloading position inside the container 168, for example, if it is the first time it is being carried in, it is determined that the load W has come into contact with the front wall 174 of the container, and if it is being carried in thereafter, If so, it is determined that the load W on the fork 12 has come into contact with and been pressed against the previous load W in the container 168, as shown in FIG.

Based on this, in step S8, the forklift truck 2 is stopped by stopping the drive motor 126 and operating the electromagnetic brake 152 and the hydraulic brake 154. Furthermore, in step S9, CPU1
20 controls the operation of the electromagnetic pulp 158 via the cargo handling control circuit 146 and lowers the lift cylinder 22 of the cargo handling device 160, thereby lowering the cargo W together with the fork 12 to the unloading position. Therefore, fork 12
The upper load W can be positioned in close contact with the container front wall 174 or the previous load W.

The forklift 28 that has unloaded the cargo W inside the container 168 retreats along the container side wall 170 and the guide wall 30 and returns to the waiting station ST again. The cargo will be efficiently loaded within 6 days.

The above is an explanation for container vanning, but even in on-site transportation work on the platform 162 etc., by executing the program as described above, the cargo W on the fork 12 can be moved forward, sideways, or sideways on the way. If it comes into contact with a container rack, load, transport equipment, or other obstacle, it can be brought to an emergency stop, and if it comes into contact with a load in front of it at the unloading position, it can be stopped and unloaded.

Note that the vibration pickup 60 can be provided at the base of each fork 12 instead of being provided at the tip of each fork 12, and in addition to the fork 12, a member integral with the fork 12, such as a finger bar 20, etc. It is also possible to provide one or more.

Also, instead of the flowchart shown in FIG. 8, when the detected value (number of pulses) of the pulse pink-up 128 reaches the set value (set number of pulses), the flag register of the C'P U 120 is set to ON. and comparator 6
8 issues an output signal, it may be determined in step S5 whether or not the flag register is in the ON state, and steps S6 or S8 and subsequent steps may be executed based on the determination result.

In addition, as another aspect, the comparator 6 in FIG.
Vibration pickup 6 without providing 8 or setting device 70
0 output signal to amplifier 64. After passing through the filter 66, A
The signal is supplied to the CPU 120 of the on-board microcomputer via the /D converter, and a standard signal pattern when the cargo W comes into contact with an object on the track is stored in the Memo+7122.
It is also possible to have the CPU 120 determine whether there is contact with the cargo W based on a comparison between the signal pattern input from the A/D converter and the standard signal pattern.

Further, the guide surface detection means such as the lateral displacement sensors 32 and 34 are not necessarily of a contact type, but may also be of a non-contact type using ultrasonic waves or the like. Furthermore, if the forklift 28 is to be guided up to the entrance of the container 168, or if it is not a container vanning but a transportation work on a platform 162 or the like, the forklift 28 may be guided using well-known electromagnetic induction wires or optical reflective bands. An indirect induction method may also be used.

Furthermore, it is not essential to execute the alarm step in conjunction with the emergency stop step, and it is also possible to omit the alarm control circuit 148 and the alarm device 161 to omit the alarm step.

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 the drawing]

FIG. 1 is a plan view schematically showing a forklift truck according to an embodiment of the present invention, and FIG. 2 is a side view thereof. Third
The figure is an enlarged sectional view showing a part of FIG.
FIG. 4 is a sectional view taken along the line ■-■ in FIG. 3. FIG. 5 is a block diagram schematically showing the control circuit of the forklift. FIG. 6 is a plan view schematically showing an example of how the forklift is used, and FIG. 7 is a side view thereof. FIG. 8 is a flowchart showing a part of the forklift control program. FIG. 9 is a plan view showing an example of a state in which the cargo is in contact with the side wall of the container, and FIG. 10 is a plan view showing a state in which the cargo is in contact with the previous cargo in the container. 2: Vehicle body 12 Fork 14: Outer mast 16: Inner mast 18: Lift bracket 20: Finger bar 30 guide wall 32.34:
Lateral displacement sensor 48: Linear potentiometer 60: Vibration pickup (vibration detection device) 64: Amplifier 66: Filter 68: Comparator
70: Setting device 120: Microprocessor (CPU)
122: Memory 124: I10 interface 140
: Traveling control circuit 126: Drive motor 128: Pulse pickup (traveling distance detection device) 140: Traveling control circuit 142 Ni steering control circuit 144 Nib brake control circuit 146: Cargo handling control circuit 160: Cargo handling device 162 Nibrat home 168: Container 170.172:
Container side wall 174: Container front wall

Claims (1)

[Scope of Claims] A forklift that can be driven unmanned along a predetermined track by loading a load on a front cargo handling device having a fork, the forklift being provided on the fork or a member integral with the fork, and provided on the fork or a member integral with the fork, so that the load is placed on the front cargo handling device. a vibration detection device that is activated by detecting vibrations generated in the fork when it comes into contact with an object in a travel path; a travel distance detection device that detects a travel distance of the forklift from a reference position; and a travel distance detection device that detects the travel distance of the forklift from a reference position; If the detected value of the travel distance detection device has reached a predetermined setting value, it is determined that the load has contacted the stationary wall or the load in front at the unloading position, and the forklift is stopped and the forklift is stopped. a contact vibration detection function that causes a cargo handling device to unload the load and, if the set value is not reached, determines that the load has come into contact with an object on the way and stops the forklift urgently; and a contact vibration detection function. An unmanned forklift equipped with