JP2575105B2 - Unmanned transport vehicle with emergency stop function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an unmanned transport vehicle on which a load is placed and guided by a side guide surface, and more particularly to a technique for preventing the load from contacting the guide surface.

2. Description of the Related Art In recent years, unmanned transport vehicles such as unmanned forklifts and unmanned transport vehicles for the purpose of labor saving have been used in the field of on-premise transport vehicles such as forklift trucks (hereinafter referred to as forklifts). Humans first developed an unmanned forklift guided by lateral guide surfaces. This includes inclination detecting means for detecting the inclination of the guide surface around a vertical line with respect to the vehicle, and traveling direction control means for steering the vehicle in a direction to decrease the inclination based on the detection result of the inclination detecting means. The vehicle is driven unmanned along the guide surface such that the guide surface such as a guide wall or a guide bar is kept parallel to the vehicle, and is used, for example, when sequentially loading loads from the platform into the container. .

Problems to be Solved by the Invention In an unmanned forklift guided by such a guide surface following system, the distance between the forklift and the guide surface, and consequently the distance between the load and the guide surface, is usually small, so that the vehicle is mounted for some reason. Load and guide surface (including container side wall) when deflection occurs around the vertical line
There was a problem of easy contact. For example, when a convex portion, a concave portion, a step portion, or the like is present on the guide surface, and the inclination detecting means detects the inclination as a tilt of the guide surface with respect to the vehicle,
When the traveling direction control means steers the vehicle in a direction to decrease the inclination, the load contacts the guide surface due to the deflection, or when the vehicle is shaken due to bad running conditions, the load is applied to the guide surface. There was a risk of contact.

Note that such a problem is not limited to the unmanned forklift, and may occur in other unmanned transport vehicles that are not provided with a cargo handling device.

Means for Solving the Problems In order to solve such problems, the present invention is directed to an unmanned transport vehicle loaded with a load and guided by a side guide surface as described above, which is evident from FIG. As described above, in addition to the inclination detection means and the traveling direction control means, the inclination detected by the inclination detection means is compared with the inclination detected by the inclination detection means and the maximum allowable value of the inclination. Emergency stop means for stopping the vehicle, and maximum allowable value setting means for setting the maximum allowable value of the inclination to a small value when the load width in a direction perpendicular to the guide surface of the load is large as compared to when the load width is small. Are provided.

Effect of the Invention If the unmanned transport vehicle is configured as described above, when the inclination of the guide surface around the vertical line with respect to the vehicle detected by the inclination detecting means is equal to or more than the maximum allowable value of the inclination,
Since the traveling of the vehicle is stopped by the emergency stop means, even if the vehicle body oscillates around the vertical line for some reason, contact between the load and the guide surface is prevented, and the load is protected.

Moreover, the maximum allowable value of the inclination is set to a smaller value by the maximum allowable value setting means when the load width is large than when the load width is small. It can be operated efficiently. For example, despite the small width of the load and the relatively large gap between the guide surface and the low possibility of contact, there is no waste of emergency stop of the vehicle, It is possible to keep the operating rate of the vehicle high while protecting.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

2 and 3 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, in which front wheels are drive wheels 4 and rear wheels are steering wheels 6. The vehicle body 2 is provided with a balance weight 8 on the rear side and a head guard 10 on the upper side. As is well known, a fork 12, an outer mast 14, and an inner mast
16 cargo handling devices are provided. The inner mast 16 is vertically guided by rollers by the outer mast 14, and the inner mast 16 further guides the lift bracket 18. A finger bar 20 and a back left 21 are attached to the lift bracket 18 via a side shift attachment 19,
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, the finger bar 20, the backrest 21, and the fork 12 are raised integrally by a chain (not shown). Outer mast
The lower end of 14 is attached to the vehicle body 2 so as to be rotatable around one axis. By operating the tilt cylinder 24, the cargo handling device including the outer mast 14 is tilted forward or backward. Also, by the operation of the side shift cylinder 26,
The finger bar 20, the backrest 21, and the fork 12 are shifted sideways in the left-right direction of the vehicle body 2 with respect to the lift bracket 18.

The forklift 28 can be manned by the driver's operation.
It is possible to drive unmanned by unmanned guidance using 30.

Lateral displacement sensors 32 and 34 that are in contact with the guide wall 30 and detect the distance and the running posture of the vehicle body 2 with respect to the guide wall 30 are attached to side portions of the vehicle body 2. Lateral displacement sensor
32 is a box fixed to the vehicle body 2 as shown in FIG.
The box 36 has an access member 38 provided therein. The access member 38 is fixed to the longitudinal main body part 40, crossbars 42 and 43 fixed to the one end part and the intermediate part upper surface of the main body part 40 at right angles, respectively, and fixed to the intermediate part lower surface of the main body part 40. And a slider 44, wherein the slider 44 is
Guide wall 30 with guide rail 45 fixed to box 36
Are supported movably in a direction perpendicular to a wall surface 46 (hereinafter, referred to as a guide wall surface 46 because the wall surface 46 functions as a guide surface). The access member 38 is constantly urged toward the guide wall surface 46 by two springs 47, and the amount of entry and exit from the box 36 is detected by a linear potentiometer 48. Main body of access member 38
A contact plate 52 having a U-shaped cross-sectional shape is attached to the front end of the fort 40 so as to be rotatable around an axis of a vertical shaft 50 at an intermediate portion. The contact plate 52 is normally held in a neutral position perpendicular to the main body 40 by two symmetrically arranged springs 54. Both ends of the contact plate 52 are rounded and curved in a direction away from the guide wall surface 46. As is clear from FIG. 5, the contact plates 52 are slightly exposed from the respective curved surfaces to the outside through the notches. Each of the rollers 56 is rotatably mounted, and when there is an obstruction such as a protrusion on the guide wall surface 46, the contact plate 52 rotates around the axis of the shaft 50 to assist in getting over it. If a crawler belt (circular belt) made of a flexible material is wrapped around the rollers 56 so that the crawler belt rotates while being in contact with the guide wall 46, friction with the guide wall 46 is avoided and the follow-up is performed. The properties and durability are improved.

The other lateral displacement sensor 34 has the same configuration, and the linear potentiometers of both lateral displacement sensors 32 and 34 are provided.
48, the distance between the vehicle body 2 and the guide wall 46, and thus the distance between the load W supported by the pair of forks 12 and the guide wall 46, is detected. Car body 2 on wall 46
Is detected about a vertical line with respect to. Lateral displacement sensor
32 and 34 function as inclination detecting means for detecting the inclination, and serve as distance detecting 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. Will also be fulfilled.

As is clear from FIGS. 2 and 3, both ends of the backrest 21 are adjacent to each other in the load width direction of the load W.
Optical sensors 60, 62, 64 and optical sensors 70, 72, 74 are fixed respectively. The optical sensors 60, 62, 64 and the optical sensors 70, 72, 74 serve as load width detecting means for detecting both ends of the load W in the load width direction from behind. And a light receiver. The light emitted from the light emitter is actuated by being reflected by the back of a load W (an aluminum box in this example) loaded at the center of the vehicle on the fork 12 and received by the light receiver. I do. in this case,
It is planned to transport cargo W with three different widths,
The three types of load width are detected by the detection signals of the optical sensors 60, 62, 64, 70, 72 and 74, but the load length of the load W in the front-rear direction is expected to be all constant. Have been. The sensors for detecting the width of the load may be arranged only on one side of the backrest 21, but by arranging the sensors on both sides, the reliability of the detection of the width of the load is enhanced.

Next, a control circuit for controlling the forklift 28 to travel in an unmanned state as described above is shown in FIG. In this figure, reference numeral 120 denotes a microprocessor (CPU: central processing unit), which is connected to the I / O interface 124 together with the memory 122. The I / O interface 124 includes the lateral displacement sensor 32
And 34 linear potentiometers 48, optical sensors 60, 62, 64 and optical sensors 70, 72,
In addition to 74, various sensors and switches necessary for driving the forklift 28 unattended are connected.

A drive control circuit 140, a steering control circuit 142, a brake control circuit 144, and a cargo handling control circuit 146 are further connected to the I / O interface 124, and the drive control circuit 140 includes a drive motor 148 for driving the drive wheels 4. The steering control circuit 142 is connected to a steering motor 150 for steering the steering wheel 6. An electromagnetic brake 152 for braking the motor shaft of the drive motor 148 is connected to the brake control circuit 144, and an electromagnetic valve 156 for controlling hydraulic pressure to a hydraulic brake 154 for braking each drive wheel 4 is connected to the brake control circuit 144. I have. Further, the cargo handling control circuit 146
Is connected to an electromagnetic valve 158 for controlling the supply of hydraulic pressure to the lift cylinder 22, the tilt cylinder 24, the side shift cylinder 26, and the like, and the operation of the electromagnetic valve 158 is controlled so that the fork 12 The operation of the cargo handling device 160 including the lift bracket 18 and the like is controlled.

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

In such a forklift 28, for example, as shown in FIGS. 7 and 8, a load W sent by a chain conveyor 164 installed on a platform 162 is retrofitted to the platform 162 via a transfer plate 166. It is suitably used when sequentially loading in the container 168 (automatic container vaning). The chain conveyor 164 is buried in the platform 162 so that a part of the chain slightly protrudes from the floor of the platform 162, and the forklift 28 can run over the chain conveyor 164. Further, the guide wall 30 is disposed so as to extend in a band shape at the height of the lateral displacement sensors 32 and 34 in a direction perpendicular to the platform 162, and the front end thereof is connected to the rear end of the wall surface 170 of the container 168 flush. After the forklift 28 enters the container 168, the container wall surface 170 serves as a guide surface.

First, when the load W by a chain conveyor 164 is sent to the consignee station ST _1, the forklift 28 travels from the rear of the stand Suteshin ST ₀ up to the loading dock station ST _1, the fork to the fork insertion groove or pallet load W 12 Insert. The insertion is completed and the fork 12
When the load W is supported on the upper side, the optical sensors 60, 62, 64 and the optical sensors 70, 72, 74 are selectively operated, and the detection signal thereof becomes the sixth signal.
The load W is sent to the CPU 120 via the I / O interface 124 shown in FIG. This is step S1 in the flowchart shown in FIG.

The center line of the traveling locus of the forklift 28 is determined so as to substantially coincide with the center line of the container 168 regardless of the difference in the load width of the load W. Is changed, but in step S2, the CPU 120 determines, according to the magnitude of the detected value of the load width,
The maximum allowable value of the deflection amount is obtained in a range where the front end corner of the load W does not contact the guide wall surface 46, and is stored in the memory 122.
The maximum allowable value of the inclination between the vehicle body 2 and the guide wall 46 is determined by the load W
Is set by replacing the displacement amount of the optical sensors 60 and 64 with the optical sensors 60 to 64 and 70 to 74.
It functions as the maximum allowable value setting means for setting the maximum allowable value of the inclination based on the detection result of the load width detecting means constituted by the above.

The forklift 28 loaded with the load W starts unmanned traveling along the guide wall 30, and detection signals from the lateral displacement sensors 32 and 34 contacting the guide wall 46 are sent to the CPU 120 via the I / O interface 124. The CPU 120 controls the steering motor via the steering control circuit 142 so that the vehicle body 2 and the guide wall surface 46 are maintained at a predetermined distance, and the traveling direction of the vehicle body 2 is parallel to the guide wall surface 46. By controlling 150, guidance along the guide wall surface 46 is performed. The steering control circuit 142 and the steering motor 150 together with the CPU 120 constitute traveling direction control means.

Here, for example, if the lateral displacement sensor 34 rides on the convex portion A (see FIG. 2) existing on the guide wall surface 46, an output difference occurs between the linear potentiometers 48 of the lateral displacement sensors 32 and 34, so that the forklift 28 Even if the traveling direction of the guide wall 46 is actually parallel to the guide wall 46, the lateral displacement sensors 32 and 34 detect this as inclination of the guide wall 46 around a vertical line with respect to the forklift 28, and the CPU 120
2, the forklift 28 attempts to steer in a counterclockwise direction in FIG. 2, that is, in a direction in which the load W approaches the guide wall surface 46. When the steering amount is large, the front end corner of the load W There is a risk of contact.

However, in step S3, the CPU 120 calculates how much the deflection amount of the front end corner of the load W will be if steering sufficient to eliminate the output difference between the front and rear lateral displacement sensors 32 and 34 is further performed. In step S4, the calculated shake amount is compared with the maximum allowable value of the shake amount stored in the memory 122, and when it is determined that the former is equal to or larger than the latter, the steering is not actually performed. Step S5 is executed to make the forklift 28 emergency stop. That is, the drive of the drive motor 148 is stopped via the travel control circuit 140, and the electromagnetic brake 1 is controlled via the brake control circuit 144.
Operate 52 and hydraulic brake 154 to forklift 2
In step S5, the brake control circuit 144, the electromagnetic brake 152, and the hydraulic brake 154 function together with the CPU 120 as emergency stop means.

Therefore, the front end corner of the load W is prevented from coming into contact with the guide wall surface 46, and the load W is protected. Such an emergency stop step is performed when the lateral displacement sensor 34 rides on a convex portion or a step portion of the container wall surface 170, or when the lateral displacement sensor 34 on the front side has a relatively large concave portion on the guide wall surface 46 or the container wall surface 170. Even when it falls into the stepped portion, the same processing is performed if the determination result in step S4 is YES.

In the process where the forklift 28 travels unmanned along the container wall 170 in the container 168, for example, when the front lateral displacement sensor 34 rides on an obstacle such as a convex portion, the front and rear lateral displacement sensors 32 and 34 Output difference,
The CPU 120 attempts to steer the forklift 28 clockwise in FIG. 7 in order to eliminate the output difference. At this time, there is a possibility that the right front corner of the load W contacts the container wall surface 172. However, even in such a case, the cargo W
The relationship between the distance of the container wall 172 and the container wall 170
Therefore, steps S2 and subsequent steps are similarly executed to prevent the front end corner of the load W from coming into contact with the container wall surface 172.

Furthermore, the influence of the unevenness and the step on the guide wall surface 46 and the container wall surface 170 is not affected by the floor surface of the platform 162 and the container 1
Forklift 28 due to 68 floor
Is actually generated, the actual tilt of the forklift 28 is detected based on the output difference between the lateral displacement sensors 32 and 34, and the actual deflection at the front end corner of the load W is determined based on the tilt. When the amount is calculated, the forklift 28 is emergency stopped when the amount of runout reaches the maximum allowable value described above, and contact between the load W and the guide wall surface 46 or the container wall surfaces 170 and 172 is avoided. It is.

In the embodiment described above, the load width of the load W is detected by the optical sensor, and the maximum allowable value of the deflection amount is determined according to the load width. Therefore, the contact between the load W and the guide wall surface 46 or the like is avoided. The emergency stop of the forklift 28 can be efficiently stopped only when the need actually arises. In other words, when the maximum allowable value of the shake amount is uniformly determined based on the maximum load width regardless of the difference in the load width,
Although the inconvenience of stopping the forklift 28 unnecessarily occurs even though there is no risk of contact in the load W having a small load width, the above-described embodiment does not have such a disadvantage, and the operation rate of the forklift 28 The load W can be appropriately protected according to the load width without lowering the load.

If the length of the load W in the front-back direction is different,
A predetermined load length detecting means, for example, a support member extending forward is provided on the head guard 10, and a plurality of fixed optical sensors for detecting the front end of the load are disposed on the support member, or while being guided by the support member. A movable optical sensor sent forward by a motor is provided, and a means for detecting the load length from the number of rotations of the motor until the optical sensor detects the load front end is provided. By calculating the distance between the steering center of the vehicle body 2 and the output of the lateral displacement sensors 32 and 34, it is possible to calculate the amount of deflection at the front end corner of the load W. Further, when both the load width and the load length change, it is desirable to provide a detecting means such as an optical sensor for detecting the load width and the load length, respectively.

On the other hand, the inclination around the vertical line between the vehicle body 2 and the guide wall surface 46 or the like is not indirectly grasped as the amount of deflection or displacement at the front end corner of the load W, but is measured from the steering center of the front end corner of the load W. Based on the distance and the distance to the guide wall surface 46, etc., the maximum allowable value of the inclination in a range where the load W does not contact the guide wall surface 46, etc. is directly obtained, and this is obtained by the lateral displacement sensor 32, 3
4 is stored in the memory 122 as the permissible limit (maximum permissible value) of the output difference, so that the emergency stop step is executed when the actual output difference between the lateral displacement sensors 32 and 34 exceeds the permissible value. You may.

Further, the inclination detecting means such as the lateral displacement sensors 32 and 34 is not limited to the contact type which always contacts the guide wall surface 46 and the like, and a non-contact type such as an ultrasonic sensor can also be used. Further, the guide surface for unmanned guidance of the forklift 28 is not limited to a flat surface such as a wall surface in the case of carrying work in a premises but for loading / unloading of containers, and for example, a guide rail having an arc-shaped cross section may be a roller. The curved surface may be used as the guide surface, for example, when guiding while contacting the surface.

In addition, although the present invention is suitably applied to an unmanned forklift, the present invention can be similarly applied to other unmanned transport vehicles having no cargo handling device.

In addition, although not described in detail, it is needless to say that the present invention can be implemented in a form in which various changes and improvements are made based on the knowledge of those skilled in the art.

[Brief description of the drawings]

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.
The figure is a sectional view taken along line VV in FIG. FIG. 6 shows the second
FIG. 3 is a block diagram schematically illustrating a control circuit of the forklift illustrated in the drawings and the like. FIG. 7 is a plan view schematically showing an example of a use form of the forklift, and FIG. 8 is a side view thereof. FIG. 9 is a flowchart showing a part of the control program of the forklift. 2: Body, 12 forks 14: Outer mast, 16: Inner mast 18: Lift bracket, 20: Finger bar 30: Guide wall 32, 34: Lateral displacement sensor (tilt detecting means) 46: Guide wall (guide surface) 48: Linear potentiometer 60, 62, 64, 70, 72, 74: Optical sensor (load width detecting means) 120: Microprocessor (CPU: Central processing unit) 142: Steering control circuit (driving direction control means) 150: Steering motor (driving direction control) Means) 144: Brake control circuit (emergency stop means) 152: Electromagnetic brake (emergency stop means) 154: Hydraulic brake (emergency stop means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Honda 2-1-1 Toyota-cho, Kariya City Inside Toyota Industries Corporation (72) Inventor Michio Awano 1-Toyota-cho, Toyota-shi Toyota Motor Corporation (56) References JP-A-58-22750 (JP, A)

Claims (3)

(57) [Claims] 1. An unmanned transport vehicle on which a load is placed and guided by a side guide surface, wherein the inclination detection means detects an inclination of the guide surface around a vertical line with respect to the vehicle. A traveling direction control unit that steers the vehicle in a direction to decrease the inclination based on the detection result, and compares the inclination detected by the inclination detection unit with a maximum allowable value of the inclination. Emergency stop means for stopping the vehicle; and a maximum allowable value setting for setting the maximum allowable value of the inclination to a smaller value when the load width in a direction perpendicular to the guide surface of the load is larger than when the load width is small. And an unmanned transport vehicle having an emergency stop function. 2. The apparatus according to claim 2, wherein said maximum allowable value setting means includes a load width detecting means for detecting a load width of said load in a direction perpendicular to said guide surface, and based on a detection result of said load width detecting means. The unmanned transport vehicle according to claim 1, wherein a maximum allowable value is set. 3. The unmanned transport vehicle is a forklift truck having a cargo handling device at a front portion thereof, and the cargo width detecting means is provided at a part of the cargo handling device at a predetermined distance in a cargo width direction of the cargo. 3. The unmanned transport vehicle according to claim 2, wherein a plurality of optical sensors are provided to detect both ends in the load width direction of the load placed on the loading device from behind.