JPS6220567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a travel control device for an unmanned transport vehicle that controls running and stopping of the unmanned transport vehicle at a convergence point of travel routes.

Unmanned transportation vehicles are mainly used in mass production factories or assembly factories to transport cargo used on each production line, transport cargo between each production line, and transport cargo between the end point of a production line and a warehouse. There is.

First, an example of this type of unmanned carrier will be explained with reference to FIG.

This unmanned carrier 1 has a six-wheel structure, with intermediate wheels 2a and 2b being drive wheels, front wheels 2c and 2d, and a rear wheel 2.
e and 2f are steering wheels. front wheel 2c,
The steering mechanisms 3a and 3b for the rear wheels 2d and rear wheels 2e and 2f are connected by a single steering shaft 5 via rack and pinion mechanisms 4a and 4b. The steering shaft 5 has a gear 6.
A steering angle is transmitted to this gear 6 from a steering motor 7 via a gear 8. That is, by rotating the steering shaft 5 with the steering motor 7, the same steering angle in opposite directions can be given to the front wheels 2c, 2d and the rear wheels 2e, 2f. The running driving force of the intermediate wheels 2a, 2b is transmitted from a running motor 9 via a gearbox 10 and a running shaft 11. In addition, at the front and rear ends of the vehicle body, there are light receiving element rows 1 in which a large number of light receiving elements are arranged horizontally in a line.
2a, 12b are installed, and light sources 13a, 13b each consisting of a fluorescent lamp are installed in parallel with the light receiving element arrays 12a, 12b.

An unmanned carrier with such a configuration is configured to automatically travel along a travel path while detecting reflective guides installed on the travel path. The traveling control system will be explained with reference to FIGS. 2 to 6.

FIGS. 2A and 2B show the relationship between the light receiving element array 12a, the light source 13a, and the reflective guide 14 at the front end of the automatic guided vehicle.

A reflective guide 14 made of aluminum tape or stainless steel tape with high light reflectance is pasted on the road surface 15 along the travel path of the automatic guided vehicle. When the road surface is irradiated with the light source 13a, the reflective guide 1
4, strong reflected light is obtained by specular reflection. On the contrary, from the road surface 15, diffuse reflection occurs due to the unevenness of the road surface, and in addition, weak reflected light is obtained because the reflectance is smaller than that of the reflective guide 14. The amount of reflected light is detected by the light receiving elements a1~ built into each hood 16.
Receives light at a12. This photodetector is made of, for example, CdS.
(Cadmium sulfide) whose resistance value changes depending on the amount of light received. Light receiving elements a1 to a1
In order to convert the amount of reflected light received at step 2 into a binary on/off signal, an appropriate threshold value is provided. Comparing this threshold with each of the light receiving elements a1 to a12, the light receiving element on the road surface 15 is turned off because the reflected light is weak, and the light receiving element on the reflective conductor 14 is turned on because the reflected light is strong. It becomes a signal. In this way, the road surface 15 and the reflective guide 14 are identified by processing the intensity of the reflected light from the road surface.

Next, FIG. 3 shows the relationship between the light receiving element and the steering angle.

Opposite steering angles are determined for each of the light receiving elements a1 to a12. The light receiving elements a6 and a7 have the smallest steering angle, and the steering angle increases as the light receiving element approaches the left direction, that is, the light receiving element a1, or the right direction, that is, approaches the light receiving element a12. For example, when the light receiving element a6 is turned on, a steering angle command of 10 degrees to the left is output, and when the light receiving element a10 is turned on, a steering angle command of 40 degrees is output.

However, since the actual reflective guide 14 has a certain width, there is a high possibility that the light receiving element is turned on at two or more locations, as shown in FIG. (In FIG. 2, two locations a6 and a7 are on.) Therefore, in addition to the circuit that processes the on/off signal, a steering angle extraction circuit that selects one steering angle is required. An example of the circuit is shown in FIG. The outputs of the light receiving elements a1 to a12 are converted into on/off signals by an on/off processing circuit 17. A switch 19 is connected to an extraction circuit 18 that extracts one on-signal from among the on-off signals. Depending on the command from the switch 19, the light receiving element that is turned on at the leftmost position is extracted, or the light receiving element that is turned on at the rightmost position is extracted. Other light receiving elements are ignored even if they are on. This logic is composed of gate circuits and the like. Thereby, the extracted light receiving element becomes a steering command.

The switch 19 is effective in selecting the branching direction.
When the reflective guide 14 branches left and right as shown in FIG. 5, if the switch 19 extracts the light-receiving element a3 that is turned on at the leftmost side, the unmanned carrier will enter the left branch, and the unmanned carrier will enter the leftmost branch. If the light-receiving element a7 that is turned on is extracted, the unmanned carrier will enter the right branch.

Next, a control circuit for the automatic guided vehicle in response to a steering command will be explained with reference to FIG. Reflected light from the road surface is detected by a light receiving element array 12a, converted into an on/off binary signal by an on/off processing circuit 17, and inputted to a steering angle extraction circuit 18 to select one steering angle. This steering angle is input to the servo circuit 20, and the amplifier circuit 2
1 to drive the steering motor 7. For example, a potentiometer 22 is attached to the steering motor 7 as an angle detector to detect the rotation angle. This rotation angle is fed back to the servo circuit 20, and steering is performed so that the rotation angle matches the steering angle command.

By the way, when multiple unmanned guided vehicles are run, there will be points where two travel routes meet, and at such points, two unmanned guided vehicles should be driven at almost the same time to prevent collisions between the two unmanned guided vehicles. When the unmanned carrier vehicle arrives at the location, it is necessary to temporarily stop one vehicle while allowing the other vehicle to pass first.

Figures 7A and 7B show a conventional collision prevention method at a merging point on the road.
14a and 14b are reflective guides installed on the running path, and A is their merging point. As shown in A, marks such as electromagnets 25b and 25c for temporarily stopping the unmanned carrier are installed at opposing points B and C in front of the merging point A. Furthermore, reflective photoelectric switches 26a and 26b are mounted on both sides of the unmanned transport vehicles 1a and 1b, respectively.

With this configuration, collisions can be prevented by following the steps below. That is, when the unmanned carriers 1a and 1b detect the mark 25b or 25c, they temporarily stop for a certain period of time. This certain period of time is set, for example, to be about the same as the time it takes for the unmanned carrier to pass from point B or C to point A. In this way, unless the unmanned carrier vehicles stop at points B and C at the same time, there will be no collision at point A. Also,
If the unmanned carrier vehicles stop at points B and C at the same time, or if the unmanned carrier vehicle 1b stops at point C immediately before restarting the unmanned carrier vehicle 1a that stopped at point B, a situation like B will occur. In that case, priority is given to one of them, and one of the unmanned carriers, for example 1a, is restarted first. The other unmanned guided vehicle 1b confirms that the unmanned guided vehicle 1a has restarted using a reflective photoelectric switch 26b installed on its side, and the unmanned guided vehicle 1b continues to stop at that position for a certain period of time, and then automatically restarts. do. Conventionally, collisions of unmanned carriers at merging points have been prevented in the manner described above.

However, this method has the following drawbacks.

(1) Since the passing time is processed by a timer, if one unmanned carrier vehicle derails at a merging point, etc., it is impossible to prevent the other unmanned carrier vehicle from colliding with it.

(2) A priority processing circuit is added, making the circuit more complex.

(3) Reflective photoelectric switches are installed on both sides of the unmanned guided vehicle, making it expensive.

As a method to eliminate the above drawbacks, for example,
A method described in Publication No. 52-22071 has been proposed. In this method, loop antennas are buried at points along the merging route that are appropriately distant from points B, C, and A, and a detection coil is installed on each unmanned carrier, and these loop antennas are connected to each other by the required circuit. When an unmanned guided vehicle is present at one point before the convergence point, the loop antenna at the local point is excited, and the unmanned guided vehicle that enters the other point detects this with its own coil. On the other hand, when the advancing unmanned guided vehicle passes the loop antenna at the point past point A, the loop antenna at the other point is de-energized and the stopped unmanned guided vehicle stops. It is configured to make it possible.

However, since this method is an electromagnetic induction method in which a loop antenna is buried, the following problems arise.

(1) Adjustment of detection sensitivity is difficult. In other words, since it is an electromagnetic induction method, if the detection sensitivity is increased, the magnetic field from the adjacent loop antenna or other parts will also be detected, which may cause malfunctions, and conversely, if the detection sensitivity is decreased, the intended Detection may become impossible, and malfunctions may occur as well.

(2) When it becomes necessary to change the placement of the loop antenna due to a change in the driving route or other circumstances, it is difficult to do so because the loop antenna is buried.

(3) Since it is an electromagnetic induction method and the loop antenna is buried, the above method cannot be applied if the road surface contains a dielectric material. Furthermore, the detection characteristics change depending on whether the road surface is wet or dry.

(4) Design consideration is required to maintain the resonant relationship between the loop antenna and the coil.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
To provide a running control device for an unmanned carrier vehicle that can run smoothly without causing a collision or the like with a simple configuration at a merging point of running paths.

In order to achieve this object, the present invention arranges a detection body on the side of an unmanned guided vehicle, emits a light beam with this detection body, receives the reflected light, and stops the unmanned guided vehicle depending on the presence or absence of the reflected light. , non-stop is determined, and on the other hand, when two travel routes merge to form one travel route, at the confluence point, a sensor identical to the sensing object is placed at a predetermined position along each travel route in front of the confluence point. A detected object is arranged at a height, and this detected object is composed of a passability indicator and a photoelectric switch that detects the presence or absence of an unmanned carrier vehicle, and the passability indicator is a a prism having a first surface with a reflective surface having a length longer than the coasting distance of the prism, and a second surface with a non-reflective surface having a length equal to the reflective surface, and rotatably directing the prism. It consists of a bearing and a rotary solenoid for alternately revealing the first and second surfaces of the prism.Furthermore, a photoelectric switch is installed at a predetermined position along the travel path past the merging point, and an unmanned When the transport vehicle reaches a detected object on one of the running paths before the merging point, the photoelectric switch of that detected object detects this and the rotary switch of the pass permission indicator of the other detected object is activated. The switch is switched to the side that prohibits passage, and when the unmanned guided vehicle reaches the photoelectric switch installed at a predetermined position past the merging point, the switch is switched to the side that prohibits passage. The present invention is characterized in that the passability indicator is switched to the passability side by driving its rotary switch.

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

FIGS. 8A and 8B show objects to be detected used in this embodiment. The detected object 31 is placed in a housing 32 with a window on the front surface, with a triangular prism 33 oriented laterally. A light reflective tape 34 is attached to one side of this triangular prism 33.
(For example, the product name Scotch Tape) is pasted on it. One end of the triangular prism 33 is rotatably supported by a bearing 35, and the other end is connected to the output shaft of a rotary solenoid 36. When the rotary solenoid 36 is energized or de-energized in response to an external signal, the triangular prism 33 rotates by a predetermined angle, and the surface of the light reflective tape 34 is exposed or hidden. The length of the triangular pillar 33 is set longer than the coasting distance of the unmanned carrier vehicle from receiving the stop command to stopping the vehicle. A reflective photoelectric switch 37 is installed at the top of the triangular prism 33 to detect the presence or absence of an unmanned carrier.

The object to be detected 31 configured in this manner is installed as shown in FIG. 9 A and B. That is, the detected object 31
is the unmanned carrier vehicle 1 next to the route of the unmanned carrier vehicle 1.
Once in the stopped position, it is installed with the front facing towards the unmanned carrier vehicle. On the other hand, a reflective photoelectric switch 38 serving as a detection body is attached to the side of the unmanned carrier 1 at the same height as the triangular prism 33.

Next, the unmanned carrier vehicle 1 runs on the running road,
A description will be given of a case where the detected object 31 has arrived at the installed position, that is, once the stopped position. As shown in FIG. 9A, when the side of the triangular prism 33 to which the light reflective tape 34 is attached is facing up, the unmanned guided vehicle 1 is given a stop command and the unmanned guided vehicle 1 is The reflective photoelectric switch 38 detects the reflected light from the reflective tape 34, which serves as a stop command for the unmanned transport vehicle, and the unmanned transport vehicle 1 coasts for a certain distance and then stops. Since the triangular prism 33 is longer than the coasting distance of the unmanned carrier vehicle 1, the unmanned carrier vehicle 1 can detect which state the triangular prism 33 is in even at a completely stopped position. When a command to cancel the temporary stop is input to the detected object 31 from the outside, the rotary solenoid 36 causes the triangular prism 33 to
rotates by a predetermined angle, resulting in a state like that shown in FIG. Then, the reflective photoelectric switch 38 of the unmanned guided vehicle 1 can no longer detect the reflected light, so this becomes a start command and the unmanned guided vehicle 1 starts again.

Furthermore, when the unmanned carrier 1 once reaches the stop position, if the detected object 31 is in the state shown in (B) from the beginning, there is no need to stop the vehicle 1.
The unmanned carrier 1 does not stop at that position and passes through it as it is. Whether the detected object 31 is placed in the state shown in FIG. 9A or in the state shown in FIG. 9 B is determined by an external signal input to the detected object 31, as will be described later. Further, the reflective photoelectric switch 37 within the detected object 31 detects whether or not an unmanned carrier is present at that position, and outputs the detected signal to other detected objects as will be described later.

Next, the processing circuit inside the automatic guided vehicle will be explained with reference to FIG. The output of a reflective photoelectric switch 38 installed on the unmanned carrier is input to an interface circuit 39. The output of this interface circuit 39 is input to an OR gate circuit 40 and a one shot multi circuit 41. This one-shot multi-circuit 41 operates when the reflective photoelectric switch 38 can no longer receive the amount of reflected light.
is turned on for the time the reflective photoelectric switch 38 is operating and the hold time of the one-shot multi-circuit 41. Therefore, if the inverted output of the OR gate 40 is used as the other input of the gate circuit 42 to which the travel command S is input,
Only while the OR gate circuit 40 is on, the travel motor drive command T is not output and the motor is stopped. Here, the one-shot multi-circuit 41 is
This is inserted for the purpose of ensuring sufficient stop time, and may be provided as necessary.

Next, the control of traveling and stopping of the unmanned carrier vehicle at the confluence point of the travel routes will be explained with reference to FIGS. 11A and 11B.

At the confluence point of reflective guides 14a and 14b, 3
The detected objects 31a, 31c are arranged as shown in FIG.
Wiring is done so that signals can be exchanged between 1b and 31c.

First, as shown in A, the unmanned carrier 1b runs on one of the reflective guides 14b,
When the object 31 reaches the position b, there are no obstacles near the convergence point in this state.
In b, the light reflective tape surface is hidden, so
The unmanned carrier 1b passes through the same position. At this time, the reflective photoelectric switch inside the detected object 31b detects the passage of the unmanned carrier vehicle 1b, and outputs the signal to the opposite detected object 31a. This signal indicates that an unmanned carrier is near the confluence point, and upon receiving this signal, the object 31a to be detected turns its light-reflecting tape surface upward. Therefore, while the unmanned carrier 1b is near the merging point, the other reflective guide 1
Once the unmanned carrier vehicle 1a arrives at the stop position on the side 4a, the unmanned carrier vehicle 1a detects the reflected light from the detected object 31a and stops there. This is state B. When the leading unmanned carrier vehicle 1b passes through the junction and passes the detected object 31c, a reflective photoelectric switch inside the detected object 31c detects it and outputs the signal to the detected object 31a. The object to be detected 31a receives the light and hides the light reflecting tape surface. Therefore, the stop command for the unmanned guided vehicle 1a is canceled and the unmanned guided vehicle 1a starts moving again. This is the state of Ha. At this time, the reflective photoelectric switch within the detected object 31a detects the restart of the unmanned carrier vehicle 1a, and outputs the signal to the detected object 31b. In response to this, the object to be detected 31b turns the light-reflecting tape surface outward. In this state of the detected object 31b, the unmanned carrier 1a is the detected object 3.
It continues until it passes 1c.

In the manner described above, collisions of unmanned guided vehicles at the merging point can be prevented. Note that the detected object 31c only needs to detect the passage of the unmanned carrier.

Further, in the above embodiment, optical means were used as the sensing object and the sensing object, but other than this, it is also possible to use magnetic means such as an electromagnet as the sensing object and a magnetic sensing element as the sensing object. It is.

Furthermore, in the above embodiment, an example was shown in which the unmanned carrier is stopped when the reflective surface of the object to be detected appears, but on the contrary, it is allowed to run when the reflective surface appears, and when the non-reflective surface It may be configured to stop when appears.

As described above, in the present invention, at a confluence point where two travel routes merge, when an unmanned carrier vehicle that has passed through one travel route is near the confluence point, an unmanned carrier vehicle that enters from the other travel route The vehicle is stopped using either a reflective surface or a non-reflective surface, and when the unmanned carrier vehicle passes a traveling path that has passed a confluence point, the reflective surface and non-reflective surface are reversed and the vehicle is stopped using either a reflective surface or a non-reflective surface. By allowing unmanned carriers to enter the track, it is possible to prevent collisions caused by derailments, etc.
In addition, if the times at which the unmanned guided vehicle passes each detected object on two routes are even slightly different, the photoelectric switch of the detected object that the unmanned guided vehicle passes earlier will detect the reflection of the other detected object. Since the surface and the non-reflective surface can be controlled, it is possible to prioritize the travel route by adjusting the installation position of the detected object, and it is possible to eliminate the need for a priority processing circuit. Furthermore, since an unmanned guided vehicle only needs to be equipped with a photoelectric switch on one side to detect the reflective and non-reflective surfaces of the detected object, the structure and circuit are simpler and cheaper than conventional devices installed on both sides. This makes maintenance and inspection easier. Furthermore, since running and stopping are controlled by transmitting and receiving signals between the sensing body and the detected body, the influence of external disturbances is small and reliable control can be performed.

Further, since the reflective surface and the non-reflective surface are provided on a prism and the prism is driven by a rotary solenoid so that the reflective surface and the non-reflective surface appear alternately, the structure is simple and easy to manufacture. In addition, these reflective surfaces,
Since the length of the non-reflective surface is set to be longer than the coasting distance of the automatic guided vehicle, travel control using the reflective surface and the non-reflective surface can be performed reliably.

Additionally, driving control using reflective and non-reflective surfaces is not affected by the material or condition of the driving path.
Furthermore, equipment can be easily rearranged.

[Brief explanation of the drawing]

Figure 1 is a bottom view of an example of an unmanned carrier;
Figures 2A and 2B are a plan view and a side view showing the relationship between the light-receiving element and the reflective guide of the automatic guided vehicle, Figure 3 is a graph showing the relationship between the operation of the light-receiving element of the automatic guided vehicle and the steering angle, and Figure 4 The figure is a block diagram of the steering angle extraction circuit.
Fig. 5 is an explanatory diagram for explaining steering angle extraction when the reflective guide is branched, Fig. 6 is a block diagram of the control system of the unmanned carrier vehicle in response to the steering command, and Fig. 7 A is the conventional driving route. A plan showing the confluence point of
Figure 8 (b) is an explanatory diagram for explaining the collision prevention control of the unmanned carrier, and Figure 8 (a) and (b) are enlarged side views and partially cutaway views of the main parts of the detected object used in one embodiment of the present invention. A perspective view, FIGS. 9A and 9B are front views showing various operating states of the travel control system according to an embodiment of the present invention, and FIG. 10 is a signal processing system in an unmanned carrier vehicle used in an embodiment of the present invention. FIGS. 11A, 11B and 11C are explanatory diagrams showing a collision prevention control sequence for an unmanned guided vehicle at a merging point of travel routes as an application example of the present invention. 1, 1a, 1b...Unmanned carrier, 14, 14
a, 14b...Reflection derivative, 31, 31a, 31
b, 31c... Detected object, 38... Reflective photoelectric switch (sensing object).

Claims (1)

[Claims] 1. A vehicle having a first running route, a second running route, and a third running route where these running routes merge, and detecting a guide installed in each of the running routes to drive an unmanned carrier vehicle. , a detection body disposed on a side surface of the unmanned carrier, which receives the reflected light of the emitted light and controls whether or not the unmanned carrier is stopped depending on the presence or absence of the reflected light; and the unmanned carrier. a first surface having a reflective surface longer than the coasting distance of the surface, and a second surface having a non-reflective surface having a length equal to the reflective surface; are composed of prisms that appear alternately, and the sensing body is located at a predetermined position along the first travel path and at a predetermined position along the second travel path before the convergence position of each travel path, respectively. A detected object consisting of a passability indicator arranged at the same height and a photoelectric switch provided in the same housing as the passability indicator and detecting the presence or absence of the unmanned guided vehicle, and a convergence position of each of the travel paths. a photoelectric switch installed at a predetermined position along the third traveling route past the point, and when the unmanned carrier vehicle reaches the detected object on one of the first traveling route and the second traveling route. a stop signal output means for detecting this with a photoelectric switch of the object to be detected and causing the rotary switch to actuate a prism of a passability indicator on the other travel path to a passability side;
A travel signal that detects when the unmanned guided vehicle reaches a photoelectric switch on the third travel path and activates the square pillar of the pass permission indicator located on the pass prohibition side to the pass permission side using the rotary switch. A travel control device for an unmanned carrier vehicle, characterized in that it is provided with an output means.