JPS6349196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic distance detection device that reduces the influence of disturbances.

2. Description of the Related Art Conventionally, it is well known that ultrasonic waves are used to detect the presence of an object or the distance to the object. As shown in Fig. 1, ultrasonic waves emitted from a source 4 are transmitted from a transmitter 1 toward an object 3, the reflected waves are received by a receiver 2, and an arithmetic circuit 5 receives the transmitted waves. It measures the time taken, calculates it as a distance, and displays it. However, in this conventional method, if a disturbance such as rain, wind, snow, fog, or smoke flows between the transmitter/receiver 1, 2 and the object 3, the ultrasonic wave will be blocked by the disturbance. Object 3 may not be detected, and the object may flicker at times and not be detected, and even if you try to measure the distance to object 3, the measured value will vary, making it difficult to determine the correct distance. Become.

The present invention aims to provide a distance detection device that can estimate and display as accurate a distance as possible to an object while reducing the influence of such disturbances as much as possible.

The basic idea of the present invention is to measure the distance between the transmitter/receiver installed at the tip of the ladder mounted on the ladder truck and the building facing it according to the time charts shown in Figure 2 a and b. The case of display will be described as an example.

In FIGS. 2a to 2b, the horizontal axis shows distance, and the vertical axis shows start signal ST, stop signal SP, and gate signal GC for next measurement.

The ladder of this type of ladder truck is initially set so that the tip of the ladder faces the opposing surface of the building at a predetermined distance. This interval is assumed to be 4 m. The transmitter emits ultrasonic waves to confirm whether the distance between the transceiver and the building is actually 4 meters. If the receiver does not receive the reflected wave, the building 3 and the transceivers 1 and 2 are not facing each other. Then, the tip of the ladder is turned left and right using a known turning mechanism until the receiver 2 receives the reflected wave.
When receiver 2 receives the reflected wave, it sends a start signal.
Emit ST, transmit ultrasonic waves from transmitter 1, measure the time until the reflected waves are received by receiver 2,
Calculate and detect the distance between the transmitter/receiver and the building. The transmission of the ultrasonic waves is repeated, for example, three times, and all three times, as shown in FIG. 2a, the next measurement gate signal,
For example, if the value is almost the same and indicates a distance greater than 1/2 of 4m, it is estimated twice, and if it is the same value within the above range, the two times are estimated as valid distance information, The other times are assumed to have been affected by external disturbances.

After that, the tip of the ladder is moved closer to the building by, for example, 1 meter. This is done by operating a known raising device mounted on the ladder truck. Then, a start signal ST is issued and the ultrasonic wave is transmitted from the transceiver 1. In this case, as shown in FIG. 2b, the receiver 2 uses the distance information estimated in FIG. If the distance information is smaller than, for example, 1/2 of the next measurement gate signal GC, this is not accepted as being caused by a disturbance, but only those larger than 1/2 are accepted and displayed. If the distance information is smaller than the distance set by the next measurement gate signal GC, for example three times in a row, the next measurement gate is fully opened and all distance information input thereafter is displayed. , If distance information greater than the distance information from the next measurement gate signal before it is fully opened is input, it is estimated as the distance to the building at the relevant point, and based on that, the tip of the ladder is moved closer to the building one by one.

According to this method, the distance to the structure may be estimated by the received signal affected by the disturbance, but since the disturbance is always between the structure and the transceiver, the ladder Accidents such as the tip hitting a building never occur. However, if the tip of the ladder passes through the disturbance and there is no disturbance beyond that point, the correct position with respect to the building can be detected, and even if this is not the case, the distance will become smaller as it approaches the building. Therefore, the influence of disturbance is reduced accordingly, and fail-safe distance detection is possible.

A specific configuration of the present invention based on this idea will be explained with reference to FIG.

In FIG. 3, flip-flop circuits F ₁ and F ₄ are set by a transmission start signal (hereinafter referred to as "start signal ST") from transmitter 1, and clock pulses of frequency ₁ are continuously output from reference clock SC. It is counted by a counter _C1 via a gate _G1 and temporarily recorded by a latch circuit _R1 . On the other hand, the clock pulse with a frequency of ₂ is input to the gate signal circuit GC for the next measurement via gate _G2 .
Also, flip-flops F ₂ and F ₃ are reset.
The frequency of clock pulse ₂ is set to twice the frequency of clock pulse ₁ , while the start signal
The input of ST resets the reference counter _C2 , thereby inputting ₁ signal to the reference counter _C2 . Further, the gate signal circuit GC for the next measurement takes in the data of the counter C ₁ or the latch circuit R ₁ via the data conversion circuit D ₃ , the data selector D ₂ or the data selector D ₂ , creates a signal corresponding to the measurement distance, and generates a signal corresponding to the measurement distance. Use as a gate signal for measurement.

In this embodiment, a signal corresponding to 1/2 of the measurement distance is used as the gate signal. In other words, the gate signal circuit GC for the next measurement has gates G ₂ to _2.
A clock _pulse of
This reduces the time to 1/2 and outputs it to gate _G3 . In this state, gate _G3 waits for the stop signal SP to arrive. _C2 is a reference counter which is reset by the start signal ST, thereby inputting clock pulse ₁ . The reference counter _G2 has outputs a, b and c. a is the output side where the output for resetting the flip-flops _F1 and _F4 is output, and b is the output side where the data of the counter _C1 is sent to the gate signal circuit GC for the next measurement via the data converter _D3 and the data selector _D2 . On the output side for input, C is output to gate _G8 , and a signal of "1" is given from gate _G8 to latch circuit _R1 , and the latch circuit is activated.
The data stored in _R1 is displayed via decoder _D1 . Output side a, b and c
From then on, clock pulse ₁ is input to the reference counter _C2 until the next start signal ST is input, that is, until the reference counter _C2 is reset by the next start signal ST. .

_G5 outputs to gate _G7 by simultaneously inputting the output from the set side of flip-flop _F3 and the a signal of reference counter _C2 . On the other hand, the set signal of flip-flop _F2 is also input to gate _G7 . When the stop signal SP arrives late, and therefore the current measured distance information is greater than the output information from the next measurement gate signal circuit GC, the output of the gate _G3 becomes "0" and the flip-flop _F2 is not set. If it is smaller than the output information from GC, the output of gate _G3 is “1”
Therefore, flip-flop _F2 is set and input to gate _G7 . Thereby, the gate _G7 is set and outputs to the reconfirmation command circuit _A1 consisting of a flip-flop. Reconfirmation command circuit A ₁ does that,
For example, if the data is stored three times in a row and the same is true for the fourth time, it is detected and output to the data conversion circuit _D3 and the data selector _D2 . data conversion circuit
The input to D ₃ causes the stored signal to be sent from the setting device D ₃₁ , which stores signals for receiving all distance information indicating that there is a building at a very close distance from the transmitter/receiver, for example, more than 0.2 m. The preparation for input to the gate signal circuit GC for the next measurement via the data selector _D2 is completed, and this is stored by inputting the b signal to the GC. The output of the GC is given to the gate _G3 , and the output of the gate _G3 becomes "1" by inputting the stop signal to the gate _G3 .
Flip-flop _F1 is reset and all subsequent distance information is displayed. _G6 is a gate which is made conductive by the a signal of the reference counter _C2 and the input from the flip-flop _F3 side.

When the stop signal SP is not input, that is, when the receiver does not receive a reflected wave, the output of the gate _G4 is "1" and the flip-flop _F3 is set. ₆
The output of is "1". The output of the gate _G6 is given to the reconfirmation command circuit _A1 .

A command from the reconfirmation command circuit A ₁ indicates the reference distance information from the reference distance setting device D ₃₂ , for example, 4 m is D ₃ ,
After being applied to D ₂ , it is applied to GC by the b signal of C ₂ , and gate G ₁ is maintained conductive by the output “1” of flip-flop F ₁ , and is applied to counter C _{1 .} Since it is set not to count distances longer than the standard distance (4m), the standard distance,
In other words, 4m is displayed. The C signal of the reference counter _C2 and the output of the gate _G6 are given to the gate _G9 ,
The output of the gate _G9 becomes "1", and the data of the decoder _D1 , that is, the reference distance of 4 m, is flickered on the display ID. On the other hand, due to the C signal of the reference counter _C2 and the input from the reconfirmation command circuit _A1 , the output of the gate _G8 becomes "0", which is input to the latch circuit _R1 , and the latch circuit _R1 becomes the counter _C1. The data will be stored as is and will not be output.

In such a configuration, the present invention will be described using an example in which the distance between the tip of the ladder of a ladder truck and a building is detected.

In a ladder truck, mechanical operation is normally used until the distance between the tip of the ladder and the building is, for example, 4 m. Therefore, at present, the distance between the tip of the ladder and the building is assumed to be 4 m. Ultrasonic waves are transmitted from the transmitter 1 by the start signal ST,
A reflected wave reflected by the building 3 is received by the receiver 2. A stop signal is generated when receiver 2 completes reception.
SP is sent. First, check whether the distance between the tip of the ladder and the building is actually 4 meters.

The start signal ST causes the flip-flop F ₁ ,
F ₄ is set and clock pulse ₁ is set to gate G ₁
When the stop signal _SP is input, the flip-flop _F1 is reset via the gate _G3 , and the counter _C1 finishes counting. The information of the counter _C1 is temporarily stored in the latch circuit _R1 , and the distance information of 4 m is displayed via the decoder _D1 if there is no influence of disturbance.

If the receiver does not receive a reflected wave, which is the so-called infinite distance, no stop signal is issued, and as mentioned above, the reference distance, that is, 4 m, is flickered on the display ID by a command from the reconfirmation command circuit _A1 . do.

If the distance information counted by counter _C1 is smaller than 2m, for example 1/2 of 4m, then
Measurement using ultrasound is performed three times in a row. If the distance is less than 2m all three times, start signal again.
ST is issued to start measurement, but the fourth stop signal ST causes the output of the reconfirmation command circuit _A1 to be input to the GC via the data conversion circuit _D3 and setting device _D31 . On the other hand, since the b signal of the reference counter _C2 is also input to the GC, the output of the GC becomes 1.
In this case, since the setting device D ₃₁ is configured as described above, the GC outputs all distance information greater than, for example, 0.2 m. The flip-flop _F1 is reset by this output, and the fifth and subsequent clock pulses ₁ are counted by the count _C1 ,
The distance information is displayed on the display ID. If some of the distance information displayed in this way is 3m, it is greater than 2m, so there is no input to the reconfirmation command circuit _A1 , and that information is input to the GC. Now, let the signal of 1/2 of the information be the gate signal for the next measurement.
Then, 3m is estimated to be valid distance information. In this case, the actual distance was 4 meters, but due to the disturbance it was measured to be 3 meters, but this estimate is on the safe side and an accident such as the tip of the ladder hitting a building will not occur.

The above describes an example where the tip of the ladder is temporarily stopped at a position extending 4 m from the building and measurements are taken, but in reality, the tip of the ladder is sometimes brought closer to the building and the distance information is measured. However, even in that case, since the distance only decreases continuously from 4 m, the distance can be estimated at each moment in exactly the same way as in the above case. In addition, the allowable approach distance to the building at the tip of the ladder is set in advance in the setting device 3, and the latch circuit
When the distance information from _R1 becomes smaller than the set approach distance, the comparator CP issues an alarm.

According to the present invention, infinite distances are displayed flickering as infinity, and other distance information is always displayed only within a certain distance from the building side, so it is safe. In addition, if the above-mentioned 1/2 gate signal set by the GC is taken in from the building side at a distance of 1/3, 1/4, and 1/5, the estimation becomes more reliable. It is suitable for this type of distance detection device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining a conventional distance detection method to an object using ultrasonic waves, Fig. 2 a and b are diagrams for explaining the basic idea of the present invention, and Fig. FIG. 3 is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Transmitter, 2...Receiver, 3...Building, 5...Arithmetic circuit, _A1 ...Reconfirmation command circuit, _D1 ...Decoder,
_D2 ...Data selector, _D3 ...Data conversion circuit, ₁ ,
₂ ...Clock pulse, _G1 , _G2 , _G3 ...Gate, GC
…Gate signal circuit for next measurement, ID…display, R ₁
...Latch circuit, SP...Stop signal, ST...Start signal.

Claims (1)

[Claims] 1. Conductive by a start signal issued at the same time as the ultrasonic transmitter starts transmitting, and a clock pulse is generated.
Gate G ₁ that outputs ₁ , Gate G ₂ that outputs clock pulse ₂ , Counter C ₁ that counts clock pulse ₁ , Latch circuit R ₁ that stores the count of counter C ₁ at one time, Memory of latch circuit R ₁ It is equipped with a display ID that displays information via a decoder _D1 , and the gate _G1 ,
In the case where G ₂ is made non-conductive, the next measurement gate signal circuit GC stores the gate signal for the next measurement, and the above next measurement gate signal circuit
It is equipped with a gate _G3 that receives the output of the GC and a stop signal, and the distance information detected by the count number of the reference counter _C2 from the time of receiving the start signal to the time of receiving the stop signal is used as the gate signal for the next measurement. When it is temporally larger than the gate signal for the next measurement of the circuit GC, the output of the gate _G3 is set to “0”.
, the distance information of the reference counter _C2 is displayed on the display, and the value of 1/2 of the distance information is stored in the gate signal circuit GC for the next measurement as a gate signal for the next measurement. Distance detection device. 2 Conducts by the start signal issued at the same time as the ultrasonic transmitter starts transmitting, and generates a clock pulse.
Gate G ₁ that outputs ₁ , Gate G ₂ that outputs clock pulse ₂ , Counter C ₁ that counts clock pulse ₁ , Latch circuit R ₁ that stores count information of counter C ₁ , and storage information of latch circuit R ₁ . _{The gate G 1 ,}
A gate signal circuit GC for the next measurement configured to make G ₂ non-conductive and stores a gate signal for the next measurement, and a gate G ₃ to which the output of the gate signal circuit GC for the next measurement and a stop signal are input. The measurement distance information detected by the counter number of the reference counter _C2 from the time of receiving the start signal to the time of receiving the stop signal is used as the gate for the next measurement in the gate signal circuit GC for the next measurement. When the time is smaller than the signal, the output of the gate _G3 is set to "1", and the gate
A reconfirmation command circuit A ₁ is provided which is activated by simultaneous input of G ₃ and a stop signal, and the reconfirmation command circuit A ₁ continuously outputs a plurality of pieces of distance information smaller than the output of the next measurement gate signal circuit GC. A data return circuit and a data selector are provided to receive the output of the reconfirmation command circuit _A1 , and the output of the data selector is input to the next measurement gate signal circuit. This ultrasonic distance detection device reduces the gate signal.