JP3479145B2 - Ultrasonic measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic measuring device for accurately measuring a distance by an ultrasonic wave received signal.

[0002]

2. Description of the Related Art Generally, for measuring a distance by ultrasonic waves, ultrasonic waves are transmitted from an ultrasonic transducer, reflected waves from an object are received by ultrasonic signals, and the ultrasonic waves are detected at a predetermined level or higher. The distance is calculated from the time between transmission and reception of ultrasonic waves when a signal is input.

[0003]

However, in such a distance measurement, the time when a signal having a level higher than a predetermined level is input when the level of the received signal is strong and when the level of the received signal is weak is deviated. There is a drawback that an error occurs in measurement.

[0004]

According to the present invention, an ultrasonic wave is transmitted from an ultrasonic vibrator by an output from a wave transmission circuit, and a received signal received by the ultrasonic vibrator is converted into digital data by an AD converter. In an ultrasonic measuring device comprising an ultrasonic processing device for converting into, storing in a memory, and reading and processing a digital signal stored in the memory by a control device including a CPU,
The digital data stored in the memory is read by the control device, and the absolute value of the data difference of the phase difference of 180 degrees in the reflected wave signal of the read digital data is sequentially stored in the memory, Distance data is output from the output terminal based on the difference between the time when the peak value is estimated to be 0 from the change value of the absolute peak value and the time when the ultrasonic wave is transmitted from the wave transmission circuit.

[0005]

According to the present invention, the absolute value of data having a phase difference of 180 degrees in the reflected wave signal in the digital data read from the memory is sequentially stored in the memory, and when the peak value of this absolute value becomes zero. By outputting the distance data from the difference between the estimated calculation time and the time output from the wave transmission circuit, even if noise is input before the reflected wave signal, the phase difference is always calculated only by the reflected wave signal. Since the time when the reflected wave signal is input is estimated from the absolute value of the 180-degree data, the distance can be accurately measured.

[0006]

1 is a block diagram of an ultrasonic measuring device according to an embodiment of the present invention, in which a wave transmitting circuit 2 and a wave receiving circuit 3 are connected to an ultrasonic transducer 1 and the wave receiving circuit 3 has an AD circuit. The converter 4 is connected, the output of the AD converter 4 is input to the memory 5, the output of the memory 5 is connected to the control device 6 including a CPU, and the control device 6 controls the address of the memory 5. 7 outputs an address signal, and the controller 6
Outputs an oscillation signal to the wave transmission circuit 2, and an 8-bit counter 8 including an oscillator outputs a pulse signal to the AD converter 5 and the address circuit 7.

The operation of the ultrasonic measuring apparatus of this embodiment will be described with reference to the flow chart of FIG. 2. First, the transmitting signal is transmitted from the transmitting circuit 2 to the ultrasonic transducer 1 by the first signal from the control apparatus 6. Then, ultrasonic waves are transmitted from the ultrasonic transducer 1 to the object.

The ultrasonic wave transmitted from the ultrasonic oscillator 1 is reflected by the object and returned to the ultrasonic oscillator 1 to be received again. The received signal is amplified by the receiving circuit 3 and is then converted into an AD converter. 4 and stored in the memory 5 (step 1). The stored waveform of the received signal is reflected by the object A transmitted from the ultrasonic transducer 1 and the object as shown in FIG. The received signal B received by the receiver is received.

Next, when the transmission signal is transmitted from the transmission circuit 2 to the ultrasonic signal 1 by the second signal from the control device 6, the reception signal is similarly amplified by the reception circuit 3 and AD converted. Although it is stored in the memory 5 through the instrument 4 (step 2), the stored waveform of the received signal is also similar to the signal A transmitted from the ultrasonic transducer 1 as shown in FIG. The received signal B reflected by the object and received is received.

As described above, the received signal is stored in the memory 5 by the first and second transmitted signals, and the two signals are read out by the controller 6 and are correlated and stored in the memory 5 ( Step 3).

Then, the time (distance) in which the ultrasonic waves make a round trip to the object is calculated and stored from the time when the first or second transmission signal is emitted and the time when the reception signal is received (step). 4).

Next, the ultrasonic wave of the third time is emitted from the ultrasonic vibrator 1, reflected by the object, and the received signal received by the ultrasonic vibrator 1 is amplified by the receiving circuit 3, AD converter 4
Then, the pulse signal from the 8-bit counter 8 is converted into digital data of the transmission signal A and the reflection signal B as shown in FIG. 5 and stored in the memory 5 (step 5). When noise N is mixed in before, and when the reflected signal A in FIG. 5 is enlarged and shown, noise N is included in the front part of the reflected signal B as shown in FIG.
Therefore, an error occurs in the time when the reflected wave B is accurately input.

Therefore, the digital data shown in FIG. 6 stored at the address 1 ms before the time corresponding to the distance confirmed in step 4 is read out, and the absolute value of the difference of 180 degrees in this digital data is read by the control device 6. Is calculated (step 6).

In this calculation, the black circle is A, as shown in FIG.
The sampling time of the D converter 4 is ts, and 1/2
Dividing the wavelength (1 / 2λ) by the sampling time ts,
The phase is 180 degrees, and at this phase, from ts0 to t
When the absolute difference value is calculated at each sampling time ts of s180, the absolute peak values P1, P2, ... Ps, Ps1, ... Pe, ... P as shown in FIG.
It can be obtained by calculating n (step 7).

Then, as shown in FIG. 9, a function y = f (x) is derived from the changes in the peak values (step 8),
The value of x + 1 ms at y = 0 of this function y = f (x) becomes the accurate time at which the reflected wave arrives, and accurate distance data can be obtained from the time estimated as the ultrasonic wave emission time (step 9). ), This distance data is output from the output terminal 9 (step 10).

Then, the control device 6 judges whether or not there is the next measurement (step 11), and if there is, returns to step 1 to repeat the above steps, and if not, ends.

In the above embodiment, the time when the reflected wave arrives in advance is measured by taking the correlation in the first two measurements, but the distance is not measured first, and the received wave is received from the beginning. It is also possible to take digital data of the signal and calculate the peak value from an appropriate time.

[0018]

As is apparent from the above description, in the ultrasonic measuring device of the present invention, the digital data of the received signal is taken in, the peak value of the absolute value of this digital data is calculated, and the peak value of this peak value is calculated. The change is converted into a function y = f (x), the time at which the peak value becomes 0 is estimated from the value of x at y = 0, and this time is regarded as the time at which the received signal arrives. Since the distance is obtained from the time and the time when the transmitted signal is emitted, the distance can be accurately calculated regardless of the noise of the received signal.

[Brief description of drawings]

FIG. 1 is a block diagram of an ultrasonic measurement device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the measuring device in FIG.

FIG. 3 is a waveform of a first reception signal received by the ultrasonic measurement device according to the present embodiment.

FIG. 4 is a waveform of a second received signal received by the ultrasonic measurement device according to the present embodiment.

FIG. 5 is a waveform of 8-bit digital data from an AD converter, which is a third received signal received by the ultrasonic measurement device of the present embodiment.

6 is an enlarged signal waveform of a reflected signal portion of the digital data of FIG.

FIG. 7 is an enlarged waveform diagram of FIG. 6 for calculating an absolute value of a peak value.

FIG. 8 is a graph showing peak values.

FIG. 9 is a diagram for deriving a function from a peak value.

[Explanation of symbols]

1 Ultrasonic transducer 2 amplifier 3 wave transmission circuit 4 AD converter 5 memory 6 control device 7 Address control circuit 8 counter 9 output terminals

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Claims (2)

(57) [Claims] 1. An ultrasonic wave is transmitted from an ultrasonic transducer by an output from a wave transmission circuit, a received signal received by the ultrasonic transducer is converted into digital data by an AD converter, and stored in a memory, In an ultrasonic measurement device including an ultrasonic processing device that reads and processes a digital signal stored in the memory with a control device including a CPU, the control device reads the digital data stored in the memory, and reads the digital data. Phase difference 180 in the reflected wave signal of the digital data
The absolute value of the difference in the degree data is sequentially stored in the memory, and the time between the time when the peak value is estimated to be 0 from the change value of the peak value of the absolute value and the time when the ultrasonic wave is transmitted from the wave transmission circuit An ultrasonic measuring device, wherein distance data is output from an output terminal based on the difference. 2. The time when the reflected wave signal is input is measured by correlating the received wave signal by outputting the transmitted wave signal twice from the wave sending circuit, and is measured the third time from that time. 2. The ultrasonic measuring device according to claim 1, wherein the digital data of the reflected wave signal is read, distance data is calculated and output based on the time estimated and calculated from the digital data and the time based on the correlation.