JPS5990111A - Obstacle detector of unmanned guiding truck - Google Patents

Abstract

PURPOSE:To eliminate a malfunction due to the counter traveling of unmanned guiding trucks and disturbance for an obstacle detector of the unmanned truck, by receiving the reflection component of the light radiated synchronously with a random pulse signal and detecting an obstacle with the received signal and said pulse signal. CONSTITUTION:An obstacle 4 is detected by an obstacle detector mounted on an unmanned guiding truck to perform the control to stop the traveling or decelerate the traveling speed of the truck. This obstacle detector is provided with a transmitting part 30 where the light is radiated synchronously with the random pulse delivered from a random pulse generating circuit 10 and receiving parts 18-21 which receive the reflection component of said light sent from the obstacle 4 and at the same time deliver a signal S1 of a fixed level when the reflection component exceeds the 1st decided value VS1. At the same time, the detection signal S1 delivered from said receiving part compares 28 each output of the 2nd AND circuit 26 obtained via the 1st AND circuit 22 and an inverter 25 with the 2nd decided value VS2 in order to obtain an AND with the random pulse. Thus a detection signal S6 and a non-detection signal S7 are obtained for the obstacle 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an obstacle detection device for an unmanned guided vehicle that is mounted on the unmanned guided vehicle and detects obstacles on a travel path.

As is well known, unmanned guided vehicles are widely used in factories and the like, contributing to labor savings and automation. This unmanned guided vehicle is equipped with an obstacle detection device that detects obstacles on the road, and when an obstacle is detected, controls such as stopping or decelerating the vehicle are performed. Here, FIG. 1 shows a schematic configuration of an optical obstacle detection device. In this figure, 1 is an unmanned guided vehicle, 2 is a light projecting section made up of a light emitting diode, etc., and 3 is a light receiving section made up of a phototransistor etc. Further, 4 is an obstacle in front of the travel path, 5 a is the irradiated light from the light projecting section 2 , and 5 b is the reflected light reflected by the obstacle 4 and received by the light receiving section 3 . In the figure, both the irradiated light 5a and the reflected light 5b are shown as straight lines, but in reality, the irradiated light 58. is the light that spreads forward, and the reflected light 5
b is the scattered light that is diffusely reflected on the surface of the obstacle 4. This optical obstacle detection device is designed to detect that an "obstacle is present" when the amount of light received by the light receiving section 3 exceeds a set level.

By the way, in a site where there are multiple running routes for unmanned guided vehicles, for example, as shown in FIG.
There may be a zone X where the slbs run directly opposite each other. In this zone Even if the vehicle 1aslb is quite far away, both obstacle detection devices malfunction and detect that there is an "obstacle".

As described above, conventional obstacle detection devices have the serious drawback of malfunctioning when an unmanned guided vehicle approaches them.1 Furthermore, they also have the drawback of malfunctioning in response to external disturbances (disturbing light, etc.). there were.

The present invention has been made in view of the above-mentioned circumstances, and provides an obstacle detection device for an unmanned guided vehicle that does not have to worry about malfunction even when the unmanned guided vehicle is running oppositely, and also does not malfunction in response to external disturbances. , a random pulse generation circuit that generates a random pulse signal, a transmitter that emits light in synchronization with the random pulse signal, and a transmitter that receives a reflected component of the light and whose reception level exceeds a first determination value. a receiving section that outputs a signal at a certain level when the receiving section outputs a signal at a certain level;
a second AND circuit that takes an AND of the output signal of the receiving section and the inverted signal of the random pulse signal;
A comparison unit that outputs an obstacle detection signal and an undetectable signal by smoothing the output signals of the second AND circuit and mutually comparing each level value obtained as a result with a second determination value. It is.

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

FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention.

In this figure, 10 is a random pulse generation circuit that generates random pulses, and includes an oscillator 0SCn bit shift register 11 and an exclusive OR gate (
(hereinafter referred to as EX-OR) 12. In this case, the output terminals α-811 and Qn-z of the n-1 and n-2 bits of the shift register 11 are connected to the input terminal of the EX-OR 12, respectively, and the output terminal of the EX-OR 12 is connected to the input terminal of the shift register 11. The output terminal of the oscillator O8C is connected to the clock input terminal CLK of the shift register 11. Further, the shift register 11 is configured such that an arbitrary bit pattern is preset to each output when the power is turned on. According to such a configuration, the output terminal Qn of the n-th bit of the shift register 11
For example, the signal outputted from the pulse train RP is a random pulse train RP as shown in FIG. This pulse signal RP has periodicity, and this period can be set to a desired period by the number of bits of the shift register 11. 15 is LE
An inverter for driving D (light emitting diode) 17, 16 is a resistor for current limiting, this inverter 15, resistor 16, and LEDI7 constitute a light emitting section 30, and when the pulse signal RP is at "H" level, LEDI
7 is designed to emit light. 18 is a phototransistor that receives the light reflected by the obstacle 4, and the voltage ``a'' obtained at the connection point between its emitter and the emitter resistor 19 is amplified by the amplifier 20 and then applied to the ``input terminal'' of the comparator 21. Supplied. The comparator 21 outputs an "H" level signal when the voltage supplied to the input terminal exceeds the comparison voltage supplied to the e input terminal by one minute. 22 is an AND gate that performs a logical product of the pulse signal RP and the output signal S1 of the comparator 21, and its output signal S2 is smoothed by a low-pass filter 23. 25 is an inverter that inverts the pulse signal RP; 26 is an output signal R of the inverter 25;
This is an AND gate that performs a logical product of P and signal S1, and its output signal S4 is smoothed by a low-pass filter 27. 28 mutually compares the values of the signals S, ,S, and the comparison voltage Vs□ to determine whether there is an obstacle or not and whether or not the obstacle can be detected, and determines whether there is an obstacle. If so, the output signal S6 is set to "H" level and S7 is set to "L" level, and when it is determined that there is no obstacle, both signals So and S7 are set to L" level number ↓ "Undetectable". When a decision is made, the signals Sa and Sy are both “I(
The details of this comparison/judgment section 28 will be described later.In addition, the comparison voltages v131 and VB2 in the above-mentioned configuration can each adjust the set voltage, and adjusting The detection distance changes, and adjusting VB□ changes the level to which light from other sensors and disturbance light is allowed to mix.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 to 5.

First, the operation when there is no disturbance light or irradiation light from an oncoming vehicle will be described. Waveforms of various parts of the circuit in this case are shown in FIGS. 4(a) to 4(b).

Section T1 shown in FIG. 4 is a section where there is an obstacle 4 (see FIG. 3) on the path of the unmanned guided vehicle, and in this section T1, the pulse signal RP (see FIG. )) The irradiated light from the LED 17 that emits light in synchronization with is reflected by the obstacle 4 and is received by the phototransistor 18.

As a result, the waveform of the voltage VFL (FIG. 4 (c)) is approximately the same as that of the pulse signal RP, and the signal S, which is a signal obtained by shaping this waveform (FIG. 4), is also the pulse signal R.
The waveform is approximately the same as that of P. As a result, the pulse signal RP
The signal 82 which is the AND of the signal S1 and the signal S1 (Fig. 4 (e)
) has the same waveform as the voltage Va that is proportional to the amount of received light, but
The signal S4, which is the logical product of the signal ■ (inverted signal of the pulse signal RP) and the signal S1, is always 0L as shown in Figure 4 (G).
” level. Therefore, the signal S.

The signal S, which is obtained by smoothing the signal S, is always at the III11 level, but the signal S, which is obtained by smoothing the signal S, is always at a high level as shown in FIG. Then, the comparison judgment section 2
8, while the signal S exceeds the comparison voltage W a ', that is, from time t1 to t2, it is determined that there is an "obstacle", and the signal S6 is set to "H" level and 87 is set to L level (No. 8). Figure 4 (for the man).

Next, in the section T2 where no obstacle 4 exists, the phototransistor 18 does not receive light, so the voltage Va maintains the "L" level as shown in FIG. 4(c), and therefore the signal S□ ~SO all maintain the ``'v level.

In this way, when No. 6 33.86 are both at the "L" level, the comparison/judgment section 28 determines that "there is no obstacle" and the signal S
6. Set both S7 to ``L'' rehe A/ (Fig. 4)
, (nu)).

Next, a case in which the transistor 18 receives irradiated light from an oncoming vehicle or continuously irradiated disturbance light will be described. The waveforms of each part of the circuit in this case are shown in Figure 5 (1') to (
In this figure, section T3 indicates the case where there is irradiation light from an oncoming vehicle, and section T4 indicates the case where there is disturbance light. In addition, the waveform shown in (Gin) of this figure is the random pulse signal RP' of the oncoming unmanned guided vehicle (that is, the waveform shown in the LED light emission timing of the oncoming vehicle) indicates strong disturbance light NL.

First, if there is an unmanned guided vehicle traveling in the opposite direction (section T
, ) will be explained.

Random pulse signal RP%R of opposing unmanned guided vehicle comrades
P' has different waveforms and synchronization, as shown in FIGS. 5(a) and 5(b). Moreover, since the voltage V a 's signal Sl corresponds to the amount of received light, it has the same waveform as the pulse signal RP' of the other party, as shown in (E) and (F) of the figure. As a result, the signal S2, which is the logical product of the signal S1 and the pulse signal RP, becomes a signal in which each "H" level period of the signal S1 is shortened by 1 (or eliminated), and the signal 82 as a whole is shown in FIG. Thus, the signal has a short "I4" level period. Therefore, the signal 33 (
The level in (a) of the same figure is low and always below the comparison voltage VB2. In addition, the level of the signal S4 (shown in the same figure), which is the AND of the signal S1 (see above) and the signal S1, does not exceed the comparison voltage V,2. ■
6□〉S3, VB2 From the state of >Ss, it is determined that there is no obstacle and the signals Sa, S? (see 1 in the same figure)). In this case, the signals Ss and Sa
It is also possible to make a more detailed judgment such as ``There are no obstacles, but there is an oncoming vehicle'' based on the relationship between the level values of .

Next, a case where there is disturbance light NL (section T4) will be described.

When there is a large disturbance light NL that is continuously irradiated, the voltage Va
As shown in section T4 in FIG. As a result, the levels of the signals Ss and S both exceed the comparison voltage ■s2.Then, the comparison/judgment unit 28 determines the time t when both the signals Ss and SS exceed the constant voltage ■82.
After that, it is judged as “undetectable” and the signal 86% S7 is set to “H”.
(Fig. 5 0 → use)).

Note that the circuit for generating random pulses in the above-described embodiments is not limited to that shown in the embodiments, and can be modified to some degree by applying an analog circuit.

Further, the determination method in the comparison and determination section 28 includes, for example, providing a dead zone in the determination reference value (Vs,), and
A method such as comparing the difference in s and the judgment base value may be used.

Furthermore, in this embodiment, the comparison voltage V B I
s VB 2 value? By adjusting each, you can arbitrarily set the distance for detecting obstacles and the tolerance of disturbance light, so you can set the optimal detection distance and tolerance of disturbance according to the current situation. be able to.

As explained above, according to the present invention, there is provided a random pulse generation source that orders a random pulse signal, a transmitter that emits light in synchronization with the random pulse signal, and a transmitter that receives the reflected component of the light. a receiving section that outputs a signal at a constant level when the level exceeds a first judgment value; a first AND circuit that takes a logical product of the output signal of the receiving section and the random pulse signal; A second AND circuit that takes a logical product of the output signal and the inverted signal of the random pulse signal, and a second AND circuit that smooths the output signals of the 'P; Second
1. Comparing section that outputs an obstacle detection signal and an undetectable signal by mutually comparing judgment values of 1. Therefore, there is an advantage that the system does not malfunction even when the unmanned TFJ guided vehicles run opposite each other, and that the A4 system does not operate even when there is a significant disturbance.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a schematic configuration of an optical obstacle detection device, Fig. 2 is a plan view showing a zone , Figure 4 (d) is a waveform diagram of each part of the circuit shown in gS3 in the absence of the opposing unmanned guided vehicle and disturbance light, and Figure 5 (a) to υ) is the waveform diagram of the opposing unmanned guided vehicle and each part of the circuit shown in gS3 FIG. 4 is a waveform diagram of each part of the circuit shown in FIG. 3 when there is a guide car and disturbance light; FIG. 10...Random pulse generation circuit, 18...
- Phototransistor (receiving part), 19 - Song emitter resistor (receiving part), 20 - Song amplifier (receiving part), 21...
・ Comparison! a (receiving section), 22...AND gate (first r-F circuit), 23... low pass filter (comparison section), 26-... AND gate (second
cv an'F circuit), 27...Low pass filter (Jti1%), 28...Comparison/judgment section (comparison section). Applicant: Shinko Kyoki Co., Ltd.

Claims (1)

[Claims] 1. A random pulse generation circuit that generates a random pulse signal, a transmitter that emits light by applying the same JI to the random pulse signal, and a transmitter that receives the reflected component of the light and adjusts the reception level. A receiving section that outputs a signal at a certain level when the first judgment value is exceeded, and a logical product of the output signal of the receiving t'W19 and the random pulse signal? a first AND circuit that takes the logical product of the output signal of the receiving section and the inverted signal of the random pulse signal;
1. A ratio axis section that outputs an obstacle detection signal and an undetectable signal by smoothing each of the output signals of the second AND circuit and mutually comparing each level value obtained as a result with a second judgment value. An obstacle detection device for an unmanned guided vehicle, characterized by comprising: 2. '1) The obstacle detection device for an unmanned guided vehicle according to claim 1, wherein the distance at which the obstacle is detected is set by changing the first determination value iJ.