JPS61267697A - Unmanned cart having emergency stoppage 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 Technical Field The present invention relates to an unmanned transportation vehicle that carries a load and is guided by a side guide surface, and particularly relates to a technique for preventing the load from coming into contact with the guide surface.

BACKGROUND ART In recent years, in the field of on-site transportation vehicles such as forklift trucks (hereinafter referred to as forklifts), unmanned transportation vehicles such as unmanned forklifts and automated guided vehicles have been used for the purpose of labor saving. Humans have previously developed unmanned forklifts that are guided by lateral guide surfaces. This includes an inclination detection means for detecting the inclination of the guide surface around a line perpendicular to the vehicle C, and a running direction control means for steering the vehicle in a direction to reduce the inclination based on the detection result of the inclination detection means. The vehicle is driven unmanned along a guide surface such as a guide wall or guide bar so that the vehicle is kept parallel to the guide surface, and is used, for example, when loading cylinders one after another from a platform into a container. be.

Problems to be Solved by the Invention In an unmanned forklift that is guided by such a guide surface tracking method, "the distance between the forklift and the guide surface, and the distance between the load and the guide surface are usually small, so if the vehicle If the load and guide surfaces (including container side walls, etc.) oscillate around the vertical line,
There was a problem that they easily came into contact with each other. For example, when a protrusion, a recess, a step, etc. exist on the guide surface and the inclination detection means detects this as an inclination of the guide surface with respect to the vehicle, the traveling direction control means moves the vehicle in a direction that reduces the inclination. When the vehicle was steered, there was a risk that the load could come into contact with the guide surface due to the deflection, or when the vehicle was swayed due to poor track conditions, the load could come into contact with the guide surface.

Furthermore, such problems are not limited to unmanned forklifts.
This problem may also occur with other unmanned transportation vehicles that are not equipped with a cargo handling device.

Means for Solving the Problems In order to solve such problems, the present invention provides an unmanned transportation vehicle that carries a load and is guided by side guide surfaces as described above. In addition to the inclination detection means and the running direction control means, the inclination detected by the inclination detection means is compared with a predetermined maximum allowable inclination value, and if the former is greater than or equal to the latter, the vehicle It is equipped with an emergency stop means to stop the system.

In addition, if the load width in the direction perpendicular to the guide surface of the load differs, the maximum permissible value of the above-mentioned inclination should be determined according to the magnitude of the detection value of the load width detection means that detects the load width of the load. I can do it.

Effects of the Invention If the unmanned transport vehicle is configured in this way, when the inclination of the guide surface around the perpendicular line with respect to the vehicle detected by the inclination detection means is equal to or greater than a predetermined maximum allowable inclination value, an emergency stop is performed. Since traveling of the vehicle is stopped by the means, even if the vehicle body swings around a vertical line for some reason, contact between the cargo and the guide surface is prevented, and the cargo is protected.

In addition, when the maximum allowable value of the above-mentioned inclination is determined according to the magnitude of the detection value of the load width detection means, the maximum allowable value of the above-mentioned inclination is set small if the load width is large; By setting the width to a large value, the emergency stop means can be operated most efficiently depending on the width of the load. For example, even though the width of the load is small and there is a relatively large gap between it and the guide surface, so there is little chance of contact, it is possible to prevent the load from making an emergency stop without causing unnecessary damage to the load. This makes it possible to maintain a high operating rate of the vehicle while providing protection.

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

FIG. 2 and FIG. 3 show an example of the case where 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, cargo handling devices including a lift (as is known, 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 and a bank rest 21 are 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 1 is raised by a chain (not shown).
8. Finger bar 20. The backrest 21 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.

Further, by the operation of the side shift cylinder 26, the finger bar 20. The backrest 21 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 guiding it 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. 4, 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 moves in a direction perpendicular to the wall surface 46 of the guide wall 30 (hereinafter referred to as the guide wall surface 46 because this wall surface 46 functions as a guide surface) by a guide rail 45 fixed to the box 36. Possibly supported.

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. , the main body portion 40 of the entry/exit member 38
A contact plate 52 having a U-shaped cross section is attached to the distal end of the contact plate 52 so as to be rotatable around the axis of a vertical shaft 50 at the intermediate portion. This contact plate 52 is made up of two symmetrically arranged springs 54.
It is normally held in a neutral position perpendicular to the main body 40.

Both ends of the contact plate 52 are both roundly curved in a direction away from the guide wall surface 46, and as is clear from FIG. Each 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 46, rubbing with the guide wall 46 can be avoided and the tracking 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 inclination of the guide wall surface 46 around the perpendicular line with respect to the vehicle body 2 is detected by the difference in the outputs of both linear potentiometers 48. Detected.

The lateral displacement sensors 32 and 34 function as inclination detection means for detecting the above-mentioned inclination, and also as distance detection means for detecting the distance between the vehicle body 2 and the guide wall surface 46 based on the output signal of each linear potentiometer 48 as described above. It will also fulfill the role of

As is clear from FIGS. 2 and 3, at both ends of the bank rest 216 there are three
Individual optical sensors 60, 62, 64 and optical sensors 70
．． 72 and 74 are fixed respectively. These optical sensors 60.62.64 and optical sensor T0.72.74 serve as load width detection means for detecting both ends of the load W in the load width direction from the rear, and each of them is connected to a floodlight. and a light receiver, and the light emitted from the projector is transmitted to the fork 1.
It is activated by being reflected off the back surface of a load W (in this example, an aluminum box) loaded at the center of the vehicle on 2 and received by a light receiver. In this case, cargo W with three different widths is scheduled to be transported, and the optical sensor 60.6
Although three types of load widths are detected by the detection signals of 2, 64.70 degrees 72 and 74, it is planned that the length of the load W in the longitudinal direction is all constant. Note that the sensors for detecting load width may be arranged only on one side of the backrest 21, but by arranging them on both sides, accuracy in detecting load width is improved.

Next, FIG. 6 shows a control circuit for controlling the unmanned running of the forklift 28 as described above.

In this figure, 120 is a microprocessor (CPU:
a central processing unit) and is connected to an I10 interface 124 along with a memory 122.

The I10 interface 124 includes the lateral displacement sensor 32.
and 34 linear potentiometers, optical sensors 60, 62.64, and optical sensors 70, 72, and 74, which are load width detection sensors, and various other devices necessary to operate the forklift unmanned. Sensors and switches 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, a drive motor 148 for driving the drive wheels 4 is connected to the travel control circuit 140, and a steering motor 150 for steering the steering wheel 6 is connected to the steering control circuit 142. It is connected. The brake control circuit 144 also includes an electromagnetic brake 1 that brakes the motor shaft of the drive motor 148.
52 is connected, and an electromagnetic valve 156 that controls oil pressure to a hydraulic brake 154 that brakes each drive wheel 4 is also connected. Furthermore, the cargo handling control circuit 146 includes the lift cylinders 22. 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.

In the forklift truck 28 configured as described above, the CPU 120 processes the activation signals of various sensors and switches including the lateral displacement sensors 32, 34, etc., according to a program stored in advance in the memory 122, and Automatically controls 28 steering, acceleration/deceleration, stopping, special standby, automatic transfer, etc.

For example, as shown in FIGS. 7 and 8, 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 the container 16B (automatic container vanning). The chain conveyor 164 is buried 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 over this chain conveyor 164. Further, the guide wall 30 is connected to the platform 162.
The front end thereof is connected to the rear end of the wall surface 170 of the container 168 flush with the rear end of the wall surface 170 of the container 168. After entering the container, the container wall 170 serves as a guide surface.

First, when the load W is sent to the load receiving station ST by the chain conveyor 164, the forklift 28 travels from the standby station ST at the rear to the load receiving station ST, and inserts the fork into the fork insertion groove of the load W or the pallet. Insert 12. When the insertion is completed and the load W is supported on the fork 12, the optical sensors 60, 62.64 and the optical sensors 70, 72.74 are selectively activated, and the detection signals are shown in FIG. sent to CPUI 20 via I10 interface 124;
The width of the cargo W is calculated. This is step S1 in the flow chart shown in FIG.

The center line of the travel trajectory of the forklift 28 is set to almost match the center line of the container 168, regardless of the width of the load W, so that the distance between the load W and the guide wall surface 46 may vary depending on the width of the load. However, in step S2, the CPU 120 determines the maximum allowable amount of deflection within the range where the front end corner of the load W does not come into contact with the guide wall surface 46, depending on the detected value of the load width. memory 1
22. The maximum allowable value of the inclination between the vehicle body 2 and the guide wall surface 46 is set by replacing it with the amount of displacement of the cargo W.

The forklift 28 carrying the load W starts unmanned travel along the guide wall 30, and the detection signals from the lateral displacement sensors 32 and 34 in contact with the guide wall surface 46 are sent to the CPU 120 via the I10 interface 124. The CPU 20 controls the steering motor 150 via the steering control circuit 142 so that the distance between the vehicle body 2 and the guide wall surface 46 is maintained at a predetermined distance, and the traveling direction of the vehicle body 2 is parallel to the guide wall surface 46. Then, guidance is performed along the guide wall surface 46. Steering control circuit 142. Steering motor 150 is C
Together with the PUI 20, it constitutes a traveling direction control means.

Here, for example, if the lateral displacement sensor 34 rides on the convex portion A (see FIG. 2) present on the guide wall surface 46, the linear potentiometer 48 of the lateral displacement sensors 32 and 34
As a result, even if the traveling direction of the forklift 28 is actually parallel to the guide wall 46, the lateral displacement sensors 32,34 detect this as an inclination of the guide wall 46 about the perpendicular line with respect to the forklift 28. ,CPU
120 moves the forklift 28 counterclockwise in FIG.
If the cargo W attempts to steer in a direction approaching the guide wall surface 46 and the amount of steering is large, there is a risk that the front end corner of the cargo W will come into contact with the guide wall surface 46.

However, in step S3, the CPU 120 calculates the amount of deflection of the front end corner of the cargo W if sufficient steering is performed to eliminate the output difference between the front and rear lateral displacement sensors 32, 34, and further calculates In step S4, the calculated deflection amount is compared with the maximum allowable deflection amount stored in the memory 122, and if it is determined that the former is greater than the latter, no actual steering is performed. Step S5 is executed to bring the forklift 28 to an emergency stop.

That is, the driving of the drive motor 148 is stopped via the travel control circuit 140, and the brake control circuit 1
44 to electromagnetic brake 152 and hydraulic brake 1
54 to stop the forklift 28, and in this step S5, these brake control circuits 144, electromagnetic brake 152 and hydraulic brake 1
54 functions as an emergency stop means together with the CPU 120.

Therefore, the front end corner of the cargo W is prevented from coming into contact with the guide wall surface 46, and the cargo W is protected. Such an emergency stop step is performed when the lateral displacement sensor 34 rides on a convex portion or step on the container wall surface 170, or when the front lateral displacement sensor 32 rides on the guide wall surface 4.
6 or when falling into a relatively large recess or step on the container wall surface 170, the judgment result in step S4 is YES.
If it becomes S, it will be executed in the same way.

In addition, when the forklift 2B runs unmanned inside the container 168 along the container wall surface 170, for example, if the front lateral displacement sensor 32 runs onto an obstacle such as a convex part, the front and rear lateral displacement sensors 32 and 34 An output difference occurs, and the CPU 20 tries to steer the forklift truck 28 clockwise in FIG. . However, even in such a case, since the distance relationship of the cargo W to the container wall surface 172 is the same as that to the container wall surface 170, steps S2 and subsequent steps are executed in the same manner, and the front end corner of the cargo W is placed on the container wall surface 172. Contact is prevented.

Furthermore, the forklift 28 actually oscillates around the vertical line due to the influence of the floor surface of the platform 162 and the floor surface of the container 168, that is, the running surface, rather than the influence of the unevenness or stepped portion of the guide wall surface 46 or the container wall surface 170. In this case, the actual inclination of the forklift 28 is detected based on the output difference between the lateral displacement sensors 32 and 34, and the actual amount of deflection at the front end corner of the load W is calculated based on the inclination, thereby reducing the deflection. When the amount reaches the above-mentioned maximum allowable value, the forklift 28 is brought to an emergency stop, and the cargo W and the guide wall 46 or container wall 170, 172 are
This will avoid contact with the

In the embodiment described above, the width of the load W is detected by the optical sensor, and the maximum allowable amount of deflection is determined according to the width of the load, so contact between the load W and the guide wall surface 46 etc. is avoided. The forklift 28 can be efficiently brought to an emergency stop only when the need actually arises. In other words, if the maximum allowable value of the amount of deflection is uniformly determined based on the maximum load width regardless of the difference in load width, there is no risk of contact with a load W having a small width, but there is no waste. In contrast to the inconvenience of having to stop the forklift 28 when the forklift 28 stops, the embodiment described above does not cause such a problem, and the load W can be appropriately protected according to the width of the load without reducing the operating rate of the forklift 28. This is possible.

However, if the width of the cargo W is all constant, the width detection means such as an optical sensor is omitted, and the maximum allowable value is uniquely set. In addition, when the width of the load is constant and the length of the load W in the front and back direction is different, a predetermined load length detection means, for example, a supporting member extending forward is provided on the helad guard 10, and the front end of the load is attached to this. A plurality of fixed optical sensors for detection may be arranged, or a movable optical sensor may be provided that is guided by its support member and sent forward by the motor, and the motor rotates until the optical sensor detects the front end of the load. By providing means for detecting the load length from the number, the distance between the front end corner of the load W and the steering center of the vehicle body 2 is calculated, and the front end of the load W is calculated based on the output difference of the lateral displacement sensors 32 and 34. The amount of runout at the corner can be calculated. Furthermore, if both the load width and load length change,
It is desirable to provide detection means such as optical sensors for detecting the load width and load length, respectively.

On the other hand, the inclination around the vertical line between the vehicle body 2 and the guide wall surface 46 etc. is not measured indirectly as the amount of deflection or displacement at the front corner of the cargo W, but rather the distance from the steering center of the front corner of the cargo W. Also, based on the distance to the guide wall surface 46, etc., the maximum allowable inclination value within the range where the load W does not come into contact with the guide wall surface 46, etc. is directly determined, and this is determined as the allowable limit for the output difference of the lateral displacement sensor 32 and 34. (maximum allowable value) may be stored in the memory 122, and the emergency stop step may be executed when the actual output difference of the lateral displacement sensors 32 and 34 exceeds the allowable value.

Further, the inclination detection means such as the lateral displacement sensors 32 and 34 are not necessarily of a contact type that contacts the guide wall surface 46 etc., but may also be of a non-contact type such as an ultrasonic sensor. Furthermore, the guide surface for unmanned guidance of the forklift 28 is not limited to a flat surface such as a wall surface, but may be a roller on a guide rail having an arcuate cross section, for example, in the case of transportation work within a premises rather than loading and unloading a container. A curved surface may be used as the guide surface, such as when guiding while contacting the guide surface.

Furthermore, although the present invention is suitably applied to an unmanned forklift, it can be similarly applied to other unmanned transportation vehicles that are not equipped with a cargo handling device.

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 diagram conceptually showing the configuration of the present invention. FIG. 2 is a plan view schematically showing a forklift according to an embodiment of the present invention, and FIG. 3 is a side view thereof. FIG. 4 is an enlarged sectional view showing a part of FIG. 2; FIG. 5 is a sectional view taken along the line ■-■ in FIG. 4. 6th
This figure is a block diagram schematically showing a control circuit of the forklift shown in FIG. 2 and the like. FIG. 7 is a plan view schematically showing an example of how the forklift is used, and FIG. 8 is a side view thereof. FIG. 9 is a flowchart showing a part of the forklift control program. 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 (tilt detection means) 46: Guide wall surface (guide surface) 48: Linear potentiometer 60. 62. 64, 70.72.74: Optical sensor (load width detection means) 120: Microprocessor (CPU: central processing unit) First cause Figure 4

Claims (3)

[Claims] (1) An unmanned transportation vehicle loaded with a load and guided by a lateral guide surface, comprising a tilt detection means for detecting the tilt of the guide surface around a perpendicular line with respect to the vehicle, and a detection result of the tilt detection means. a driving direction control means that steers the vehicle in a direction to reduce the tilt based on the tilt detection means, and compares the tilt detected by the tilt detection means with a predetermined maximum allowable value of the tilt, and determines that the former is greater than or equal to the latter. An unmanned transportation vehicle equipped with an emergency stop function, including an emergency stop means for stopping the vehicle, if any. (2) The maximum permissible value of the inclination is determined according to the magnitude of a detection value of a load width detection means that detects the width of the load in a direction perpendicular to the guide surface of the load. unmanned transport vehicle. (3) The unmanned transport vehicle is a forklift truck equipped with a cargo handling device at the front, and a plurality of the cargo width detection means are provided in a part of the cargo handling device at predetermined distances apart in the width direction of the cargo. 3. The unmanned transport vehicle according to claim 2, wherein the unmanned transportation vehicle is a photo sensor that detects both ends of the load placed on the load handling device in the load width direction from the rear.