JPS628835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mark or barcode reading device.

In general, in unmanned vehicles that can automatically travel along a predetermined track, a bar code consisting of a series of bar signs is pasted on the floor so that the unmanned vehicle can detect location information while traveling. , a method is adopted in which an unmanned vehicle reads this mark (barcode) and detects its location information.

As one of the conventional mark reading devices, bars are arranged in a direction perpendicular to the moving direction of the unmanned vehicle, and multiple detectors detect the presence or absence of the bars at once to read the bar presence/absence information. There is a reading method. However, this method required the same number of detectors as the number of bits in the barcode, making it expensive.

Another method is a serial reading method in which bars are arranged in the direction of movement of the unmanned vehicle, the bars are detected in series with one detector, the number of detected pulses is counted, and information is read from the count value. This method differs from the above parallel reading method in that the number of detectors is 1.
The advantage is that it can be done with just a few minutes. However, this method requires many circuits such as a scan circuit, a pulse generation circuit, and a counting circuit, making the device complicated and expensive. Moreover, with a system that generates pulses at a constant frequency when detecting a bar, if the moving speed of the unmanned vehicle changes, the pulse count value will fluctuate, making it impossible to detect accurate information. In order to accommodate this, it is necessary to generate pulses synchronized with the moving speed, which further complicates the device and increases costs.

Furthermore, as another mark reading method, for example, the first
As shown in the figure, two detectors (not shown) are mounted on the unmanned vehicle in a direction perpendicular to the moving direction B, and at the timing when one of the detectors detects the bar at the detection position 25a, the other detector detects the bar. The device is at the detection position 24a
There is a timing bit type serial reading system that reads information by detecting the presence or absence of the bar 26. Here, 26 is a bar that means binary "1",
27 is a bar meaning binary "0". However, in this method, if the actual movement direction A deviates from the correct movement direction B as shown in the figure, when the timing detector detects the bar 26 at the detection position 25a, the other detector detects the presence or absence of the bar. The actual detection position 24b will deviate significantly from the original detection position 24a, and such an error in the movement direction will have a sensitive effect on the reading accuracy. Moreover, in this case, since two detectors are provided in the length direction of the bar, there is also a drawback that a long bar is required as the bar 26.

This invention was made in view of the above-mentioned conventional problems, and a mark is formed by arranging first and second bars of different widths in the moving direction of a moving body, and A detector is mounted on the movable body in the moving direction thereof, that is, in the width direction of the bar, and a third detector is mounted between the first and second detectors of the movable body. detects one end of the bar in the width direction, and when the third detector detects the presence of the bar, the second detector detects the presence or absence of the bar by determining the type of bar according to the detection output, A mark reading device that can always read accurately regardless of whether the direction of movement is forward or backward, and can maintain high reading accuracy without being affected by deviations in the direction of movement or fluctuations in movement speed. is intended to provide.

Embodiments of the present invention will be described below with reference to the drawings.

2 to 5 show a mark reading device according to an embodiment of the first invention of the present application. In the figure,
Reference numeral 1 denotes a road surface which is an object to be detected, and a bar code (mark) 3 formed by encoding positional information is pasted on the road surface 1. 2 is an unmanned carrier (moving object) that travels on the road surface 1 in the direction of arrow A, and when the carrier 2 passes over the mark 3,
You can read Mark 3 and know its location. The mark 3 above has a first bar of width a ₁ (meaning a binary "0") and a second bar (meaning a binary "1") of width a ₂ (a ₂ > a ₁ ). ) are arbitrarily arranged at a distance b from each other, and in the example shown in FIGS. 4 and 5, 4 and 5 are the first bars, and 6 is the second bar. Note that each of these bars is formed using a reflecting plate.

On the other hand, a detection device 7 is disposed on the bottom surface of the transport vehicle 2, and the detection device 7 includes a first light receiving sensor (first detector) 8 that detects one end of the bar in the width direction and detects the presence or absence of the bar. It is composed of second and third light receiving sensors (second and third detectors) 9 and 10. The detection position 9a of the second light receiving sensor 9 on the road surface 1 is set at a distance d from the detection position 8a of the first light receiving sensor 8 in the direction of arrow A, that is, in the width direction of the bar. The detection position 10a of the third light receiving sensor 10 is set at a distance e from the detection position 8a of the first light receiving sensor 8 in the width direction of the bar. However, here e<a ₁ <d<a ₁
+b, d<a ₂ and e<b. In addition, the transport vehicle 2 has a light emitting element (not shown) that emits light downward.
is provided, receives the outputs of the first to third light receiving sensors 8 to 10, the first light receiving sensor 8 detects one end of the bar in the width direction, and the third light receiving sensor 10 detects the presence of the bar. It is determined whether the bar detected by the first light receiving sensor 8 is the first or second bar according to the output of the second light receiving sensor 9 when It is equipped with a reading circuit (not shown) that outputs information.

Next, the operation of this device will be explained using FIGS. 4 and 5.

When the carrier vehicle 2 is traveling on the road surface 1, its light emitting element always emits light downward, and when the carrier vehicle 2 travels in the direction of arrow A, that is, in the forward direction, and passes over the mark 3, the light emitting element always emits light downward. 1 to 3rd light receiving sensor 8 to 10
sequentially receives reflected light from bars 4 to 6 of mark 3. Then, the first light receiving sensor 8 is connected to the first bar 4.
When the starting edge 4a of the third light receiving sensor 1 is detected, the third light receiving sensor 1
Since the detection position 10a of 0 is set as e _{<a 1, it is on the bar 4, and the sensor 10 detects the presence of the bar 4, while the detection position 9a of the second light receiving sensor 9 is set as d>} a Since it is set to ₁ , it has already passed the terminal end 4b of the bar 4 and the sensor 9 does not detect the presence of the bar, so this bar 4 is determined by the reading circuit to be the first bar. Similarly, regarding the bar 5, when the first light receiving sensor 8 detects the starting end 5a of the bar 5, the third light receiving sensor 10 detects the presence of the bar 5, and the second light receiving sensor 9 detects the presence of the bar 5. Since the presence of the bar 5 is not detected, the bar 5 is also determined to be the first bar by the reading circuit. Furthermore, since the width a ₂ of the bar 6 is set as a ₂ >d, when the first light receiving sensor 8 detects the starting end 6a of the bar 6, the second and third light receiving sensors 9 and 10
The detection positions 9a and 10a are both on the bar 6, and both sensors 9 and 10 detect the presence of the bar 6, so the bar 6 is determined to be the second bar by the reading circuit. In this way, the binary position information of the mark 3 consisting of a plurality of bars can be sequentially read, and if the results are output from the reading circuit in the reading order, the binary information of the mark can be output as serial information.

The mark 3 can also be read when the transport vehicle 2 travels in the direction opposite to direction A, that is, in the backward direction. In this case, the first light receiving sensor 8 detects the edge of the bar and the third light receiving sensor 8 detects the edge of the bar. The type of bar is determined according to the output of the second light receiving sensor 9 when the sensor 10 detects the presence of a bar, that is, when the first light receiving sensor 8 detects the starting end of each bar as described above. It is something.

In the device of this embodiment as described above, the first and second
A number of light receiving sensors are arranged in the running direction, and a third light receiving sensor is provided between both sensors, so that the first light receiving sensor detects one end of the bar in the width direction and the third light receiving sensor detects one end of the bar in the width direction.
The second light sensor detects the presence of the bar.
Since the type of bar is determined and the information is read according to the output of the light-receiving sensor, it does not matter whether the transport vehicle is moving forward or backward, and the moving speed changes during reading. Accurate reading can be performed at all times. In addition, in this device, the first,
Since the interval between the third light receiving sensors is made smaller than the width of any bar, the direction of movement is determined by the output of the third light receiving sensor when the first light receiving sensor detects one end of the bar in the width direction. It is possible to determine whether the direction is forward or backward.

Furthermore, in this device, the light-receiving sensors are arranged in the direction of movement, so even if the actual direction of movement deviates from the correct direction of movement, the detection position of each light-receiving sensor on the road surface will hardly deviate from the correct position. The reading accuracy is hardly affected by the deviation in the moving direction. Furthermore, in this apparatus, even if the number of bits in the mark is large, only three light receiving sensors are required, so the number of detectors is smaller than in the conventional parallel reading system.

2 to 5 show a mark reading device according to the first invention of the present application that reads mark information as serial information, and FIG. 6 shows the first to third light receiving sensors in the first invention. The circuit configuration of the reading circuit of the mark reading device of the second invention of the present application is shown, which reads mark information as parallel information from the output. In the figure, 8, 9, and 10 are the above-mentioned first, second, and third light receiving sensors. 11 is a first pulse generation circuit which receives the output a of the first light-receiving sensor 8, and which sensor 8 is made of a monostable multivibrator that generates a pulse signal f at the rising edge of the output a;
12 is a second pulse generating circuit made of a monostable multivibrator which receives an inverted signal of the output a of the first light receiving sensor 8 and generates a pulse signal g when the output a of the sensor 8 falls; 13 is a first pulse generating circuit; a first AND circuit having two inputs: the output f of the pulse generation circuit 11 and the output c of the third light receiving sensor 10;
is a second circuit whose two inputs are the output g of the second pulse generation circuit 12 and the output c of the third light receiving sensor 10.
It is an AND circuit. 15 is composed of a first pulse generation circuit 11 and a first AND circuit 13,
A first direction determination circuit 16 that determines whether the moving direction of the transport vehicle 2 is the forward direction or not is constituted by a second pulse generation circuit 12 and a second AND circuit 14. This is a second direction determining circuit that determines whether or not the vehicle is in the backward direction.

17 is an OR circuit having two outputs from the first and second direction discrimination circuits 15 and 16, and 18 is an OR circuit 1.
A third pulse generation circuit 19 is composed of a monostable multivibrator which receives the output of 7 and generates a pulse signal when the output of the circuit 17 rises; 19 is constituted by an OR circuit 17 and a third pulse generation circuit 18; This is a clock generation circuit that generates a clock signal CK from the outputs of the two direction discrimination circuits 15 and 16 that is synchronized with the discrimination outputs.

Further, 20 and 21 are 4-bit bidirectional shift registers (sequential storage elements), and the S ₀ terminal, S ₁ terminal, and CK terminal of both shift registers 20 and 21 have the output of the first AND circuit 13, respectively. second
The output of the AND circuit 14 and the output of the clock generation circuit 19 are added to the R terminal of the shift register 20 and the L terminal of the shift register 21.
The output D ₄ of the least significant digit of the shift register 21 is input to the L terminal of the shift register 21, and the output D ₃ of the most significant digit of the shift register 20 is input to the R terminal of the shift register 21. 22, when receiving the direction discrimination signal from the first or second direction discrimination circuit 15, 16, sets the second direction in the least significant digit or least significant digit according to the clock signal from the clock generation circuit 19. A serial-to-parallel converter circuit 23 consisting of the shift registers 20 and 21 that reads the output of the light receiving sensor 9 is constituted by the first and second direction discriminating circuits 15 and 16, the clock generating circuit 19, and the serial-to-parallel converter circuit 22. The circuit 23 is a reading circuit with
In response to the outputs of the third light receiving sensors 8, 9, and 10, the second light receiving sensor 8 detects one end of the bar in the width direction and the third light receiving sensor 10 detects the presence of the bar. It determines whether the bar detected by the first light receiving sensor 8 is the first or second bar according to the detection signal of the light receiving sensor 9, and uses the binary information of the mark 3 as parallel information. This is what is output.

Next, the operation will be explained using FIGS. 6 and 7. Here, Fig. 7 b to q are marks 3 shown in Fig. 7 a.
When the transport vehicle 2 travels in the direction of arrow A, the second
2 is a timing chart of the present device based on the detection timing of the light receiving sensor 9, and mark 3 has binary information of "01001010".

The transport vehicle 2 travels in the direction of the arrow, that is, in the forward direction,
When passing over the mark 3 from the bar of the most significant digit (MSB) to the bar of the least significant digit (LSB), the second light receiving sensor 9 detects the presence of the bar and determines the width a ₁ , a of each bar. ₂ (see FIG. 7b), and the third and first light receiving sensors 10 and 8 similarly generate detection signals c and a corresponding to the widths a ₁ and a ₂ of each bar. This occurs with a delay of a time corresponding to the distance from the second light receiving sensor 9 (see FIGS. 7c and d). The first pulse generating circuit 11 receives the output of the first light receiving sensor 8, generates a pulse signal f in synchronization with the rising edge of the detection signal a (see FIG. receives the inverted signal of the output of the first light receiving sensor 8, generates a pulse signal g in synchronization with the fall of the detection signal a (see Fig. 7f), and
The AND circuit 13 ANDs the output f of the first pulse generating circuit 11 and the detection signal c of the third light receiving sensor 10, while the second AND circuit 14 ANDs the output g of the second pulse generating circuit 12. AND is taken with the detection signal c of the third light receiving sensor 10. Now that the transport vehicle 2 is traveling in the forward direction, the first
The AND circuit 13 generates the pulse signal FP (see Fig. 7g), the output of the second AND circuit 14 remains at "0" (see Fig. 7h), and the clock generating circuit 19 generates the pulse signal FP (see Fig. 7g). A clock signal CK is generated in synchronization with the rising edge of the pulse signal FP of the AND circuit 13 (see FIG. 7i).

Then, in the serial-to-parallel conversion circuit 22, since the pulse signal FP of the first AND circuit 13 is applied to the _S0 terminals of the shift registers 20 and 21, one shift register 20 receives the pulse signal FP input to its R terminal. The clock signal of the clock generation circuit 19 which applies the output of the light receiving sensor 9 of No. 2 to the CK terminal.
Read it at the timing of CK and convert it to the least significant digit D ₀
to the most significant digit D ₃ (7th
The other shift register 21 also reads the output of the most significant digit _D3 of the shift register 20, which is input to its R terminal, at the timing of the clock signal CK. Shift from D ₄ to D ₇ (see arrows n to q in Figure 7). Therefore, the first to third light receiving sensors 8 to 10
When detects the bar of the least significant digit of mark 3, that is, when mark 3 has been read, the serial/parallel converter circuit 2
Parallel information of "01001010" as shown at the right end of FIG. 7 g to j is outputted to the output terminals D ₇ to _{D 0} of FIG.

Further, when the transport vehicle 2 travels in the direction opposite to the A direction, that is, in the backward direction, the first to third light receiving sensors 8 to 1
0 detects the bar of mark 3 from the least significant digit to the most significant digit, and the second AND circuit 14 combines the pulse signal g of the second pulse generation circuit 12 and the detection signal c of the third light receiving sensor 10. A pulse signal RP is generated by performing the AND operation. Then the shift register 20,
21 receives the pulse signal RP at its _S1 terminal, so it clocks the output of the second light receiving sensor 9.
When read at the timing of CK, it is read as the most significant digit D ₇
Shift from D to the least significant digit D ₀ . Therefore, in this case as well, the output terminal D ₇ of the serial-to-parallel conversion circuit 22
Parallel information “01001010” for mark 3 is output to D ₀ .

By the way, when the carrier vehicle 2 repeatedly moves forward and backward on a certain mark 3 and then completes the reading of the mark 3, the output of the second light receiving sensor 9 is changed every time the first light receiving sensor 8 detects the starting end of the bar. is read into the serial/parallel conversion circuit 22, and there is a risk that erroneous information may be output to the output terminals _D7 to _D0.However , in this device, the serial/parallel conversion circuit 22 reads the second The output of the light receiving sensor 9 is shifted from the least significant digit _D0 to the most significant digit D7, and when the transport vehicle 2 moves backward, the output is shifted from _{the most significant digit D7 to} the least significant digit _D0.
Therefore, even if the transport vehicle 2 repeatedly moves forward and backward on one mark 3, accurate parallel information is always output when reading of the mark 3 is completed.

Therefore, like the first device of the present invention, the device of this embodiment can maintain high reading accuracy without being affected by deviations in the moving direction or changes in the moving speed.
Moreover, only three light-receiving sensors are required, simplifying the configuration. In addition, in this device, the output of the second light receiving sensor is input to the lowest and highest digits of the serial-to-parallel conversion circuit according to the forward and backward movement of the transport vehicle, and the mark information is read as parallel information. Therefore, regardless of whether the transport vehicle is moving forward or backward, or even if the transport vehicle repeatedly moves forward and backward on one mark and then reads the mark, accurate parallel information is always obtained. be able to.

Note that in the above two embodiments, a mark reading device for reading position information of an unmanned carrier vehicle was explained.
The present invention can be similarly applied to, for example, reading information such as the type and number of an article conveyed by a conveyor or vehicle. In this case, a mark is affixed to the article being conveyed, and this is detected by a fixed detector. so that it can be read with In addition, the widths a ₁ and a ₂ of the bars, the distance b between them, and the distance d and e between the light receiving sensors satisfy the above-mentioned conditions e<a ₁ <d<a ₁
+b, d<a ₂ , and e<b, it is acceptable for there to be variations. Furthermore, the detector and bar used for mark reading are as follows:
In addition to the light receiving sensor and reflecting plate as described above, a metal detector and a metal plate, or a magnetic sensor and a magnet may be used.

As described above, according to the mark reading device according to the present invention, the mark is configured by arranging the first and second bars having different widths in the moving direction of the moving body, and the first and second bars are arranged in the moving direction of the moving body.
A third detector is mounted on the movable body in the direction of movement thereof, that is, in the width direction of the bar, and a third detector is mounted between the first and second detectors of the movable body.
When the detector detects one end of the bar in the width direction and the third detector detects the presence of the bar, the type of the bar is determined according to the detection output of the second detector. As a result, marks can be read accurately at all times regardless of whether the moving object is moving forward or backward, and high accuracy is achieved without being affected by deviations in the moving direction or fluctuations in the moving speed. Marks can be read with a single detector, and even information with a large number of bits can be read with three detectors, which has the effect of simplifying the configuration.

[Brief explanation of the drawing]

FIG. 1 is a plan view for explaining a conventional timing bit type mark reading system, and FIGS. 2 and 3 are a plan view and a side view of a mark reading device according to an embodiment of the first invention of the present application. 4 and 5 are enlarged side views of essential parts of the device and a plan view of the marks of the device, FIG. 6 is a circuit configuration diagram of a mark reading device according to an embodiment of the second invention of the present application, and FIG. is a timing chart of the above device. 1... Road surface (detected object), 2... Unmanned carrier (moving object), 3... Mark, 4, 5... First bar, 6... Second bar, 8... First bar Light receiving sensor (first detector), 8a...detection position, 9...second
light receiving sensor (second detector), 9a... detection position, 10... third light receiving sensor (third detector), 10a... detection position, 15, 16... first, second Direction discrimination circuit, 19... Clock generation circuit, 20, 21... Shift register (sequential storage element), 22... Serial/parallel conversion circuit, 23... Reading circuit.

Claims (1)

[Claims] 1. A detection target to which a mark is attached, which is formed by arranging a plurality of first and second bars with widths a ₁ and a ₂ (a ₁ < a ₂ ) with a mutual interval b. a moving body that moves relative to the detected object in the width direction of the bar; a first detector mounted on the moving body to detect one end of the bar in the width direction; Each detection position is spaced apart from the detection position of the first detector in the width direction of the bar by d, e (e<a ₁ <d<a ₁ +b, d<a ₂ , e<
second and third detectors each mounted on the movable body at the position b) for detecting the presence or absence of the bar; the first detector detecting one end of the bar in the width direction; When the detector detects the presence of a bar, it is determined whether the bar detected by the first detector is a first bar or a second bar according to a detection signal of the presence or absence of a bar from the second detector. Determine and mark 2
1. A mark reading device comprising: a reading circuit that outputs serial information as serial information. _2. A detected object to which a mark is attached, which is formed by arranging a plurality of first and second bars with widths a 1 and a ₂ (a ₁ < a ₂ ) with a mutual interval b, and the detected object. a moving body that moves relative to the body in the width direction of the bar; a first detector mounted on the moving body that detects one end of the bar in the width direction; and a first detector that detects one end of the bar in the width direction on the body; Distance d, e (e<a ₁ <d<a ₁ +b, d<a ₂ , e<
second and third detectors are respectively mounted on the movable body and detect the presence or absence of the bar so as to be located at the position b); the first detector detects one end of the bar in the width direction; When the third detector detects the presence of a bar, it is determined whether the bar detected by the first detector is the first or second bar depending on the detection signal of the second detector indicating the presence or absence of a bar. Mark 2
1. A mark reading device comprising: a reading circuit that outputs advance information as parallel information. 3. First and second direction determining circuits, wherein the reading circuit receives both outputs from the first and third detectors and determines whether the moving direction of the moving body is the forward direction or the backward direction, respectively. a clock generating circuit that generates a clock signal in response to both outputs of the first and second direction determining circuits; and a clock generating circuit that generates the clock signal when receiving the direction determining signal from the first or second direction determining circuit. A serial-to-parallel conversion circuit comprising a sequential storage element that reads the output of the second detector into the least significant digit or the most significant digit according to a clock signal from the circuit. 2. The mark reading device according to item 2.