JP2913019B2 - Distance measuring method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring method and apparatus for measuring a distance in a non-contact manner using an ultrasonic wave, a laser beam or the like.

[0002]

2. Description of the Related Art Conventionally, an FM-CW radar has been used as an effective radar system capable of easily measuring a distance. This FM-CW radar obtains distance information by changing the frequency of a carrier wave itself.

[0003]

However, this method is effective when using radio waves, but when using ultrasonic waves or laser light, frequency modulation is performed at a frequency suitable for obtaining the required measurement accuracy. It was difficult to do.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above, and it has been proposed that a carrier signal is AM-modulated or intensity-modulated by a modulation signal whose frequency continuously changes within one transmission cycle. A distance measuring method for transmitting a transmission wave generated by modulation, receiving a reflected wave from an object, and detecting a distance to the object from a difference in interference intensity caused by a phase difference with the modulation signal. Is what you do.

Further, the present invention provides a first oscillating means for outputting a carrier signal, a second oscillating means capable of continuously changing an oscillating frequency within one transmission cycle, and an output of the first oscillating means. Transmitting means for transmitting a signal by AM or intensity modulation with an output signal of the second oscillating means, transmitting means for receiving a reflected wave from a target of a transmitted wave output from the transmitting means, Interference intensity detecting means for detecting an interference intensity generated by a phase difference between an output signal of a receiving means and an output signal of the second oscillating means, and converting an output of the interference intensity detecting means into distance information from the target. An object of the present invention is to provide a distance measuring device including data conversion means.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the ultrasonic distance measuring device according to the first embodiment of the present invention. In the figure, reference numeral 1 denotes a CPU (Central Processing Unit),
Various processes are executed based on a program stored in M (Read Only Memory) 2. 3 is RAM (Random)
Access Memory) for writing and reading data from the CPU 1. Reference numeral 4 denotes a display device for displaying measured distance data and the like.

Reference numeral 5 denotes a D / A converter, which converts 8-bit digital data from the CPU 1 into an analog voltage signal and outputs a VCO (Voltage Controlled Oscilla) described later.
tor) 8 is controlled. Reference numeral 6 denotes an A / D converter, which functions to convert an analog signal into 12-bit digital data so that the CPU 1 can read the data.

Reference numeral 7 denotes a carrier oscillator, here 40 k
A sine wave signal of Hz is output (FIG. 2A). On the other hand, V
CO8 is based on the output voltage of the D / A converter 5, 1
A sine wave signal of 300 to 3540 Hz is output within the transmission cycle (FIG. 2B). The modulator 9 converts the output signal of the carrier wave oscillator 7 to the output signal of the
Modulated, and outputs a modulated signal to the transmitting means 10 (FIG. 2).
(C)).

In the present embodiment, the transmitting means 10 is constituted by a resonance type ultrasonic oscillator 10 ', and converts the modulated signal into
The ultrasonic signal is output from the ultrasonic oscillator 10 ′ to the target object Ob, and the ultrasonic signal reflected by the target object Ob is received by the receiving unit 11. In this case, the receiving means 11 is constituted by an ultrasonic sensor 11 'such as an ultrasonic microphone. The ultrasonic oscillator 10 'and the ultrasonic sensor 1
FIG. 3 shows the positional relationship between 1 'and the target object Ob. In this case, the target object Ob is composed of the table Ob2 and the book O placed thereon.
Both of b1 correspond.

The output signal of the receiving means 11 removes an unnecessary carrier through an envelope detector 12, is amplified by an amplifier 13, and is input to a mixer 14 (FIG. 2 (d)). The output signal of the VCO 8 is also input to the mixer 14,
The four input signals are homodyne-detected by the mixer 14 to generate an interference waveform signal, which is output via the RMS circuit 15 (FIG. 4). Further, the DC component is removed via the DC cut filter 16 and then input to the A / D converter 6 to be converted into digital data.

The CPU 1 samples the digital data and stores it in the RAM 3. When a predetermined amount of data is accumulated in the RAM 3, the CPU 1 performs a digital bandpass filter process and a window process to remove unnecessary frequency components, and then removes an FFT (First Fourier Filter).
Transform) processing to convert to distance information shown in FIG. As can be seen from FIG. 5, a large peak is recognized at a position corresponding to 1.5 m, which is the distance of the table Ob2, and 1.9 m, which is the distance of the book Ob1. That is, the distance between the plurality of objects Ob is measured.

Next, the above operation will be described with reference to the flowchart of FIG. First, in step S1, an initial value is set in the D / A converter data provided in a predetermined area in the RAM 3. This initial value corresponds to, for example, 300 Hz, which is the scan start frequency of the oscillation frequency of the VCO 8, for example.

In step S2, the D / A converter data is output to the D / A converter 5, and in step S3, the VCO 8
Outputs a reference oscillation signal having a frequency corresponding to the applied voltage signal.

In step S4, the carrier signal from the carrier oscillator 7 is AM-modulated in the AM modulator 9 with the reference oscillation signal from the VCO 8, and in step S5, the transmitting means 10 outputs an ultrasonic signal to the object Ob.

The reflected wave reflected by the object Ob in step S6 is converted into an electric signal by the receiving means 11, the carrier is removed by the envelope detector 12, and then amplified by the amplifier 13 to a predetermined voltage value. Is homodyne detected with the reference oscillation signal from the VCO 8 to become an interference intensity signal. Further, the RM of the interference intensity signal is transmitted through the RMS circuit 15.
An S signal is output.

In step S7, the DC component is removed through the DC cut filter 16, converted into digital data by the A / D converter 6, and the data is stored in a predetermined area of the RAM 3. Then, in step S8, the D / A
Increment the value of converter data.

In step S9, it is determined whether or not the oscillation frequency of the VCO 8 has completed a predetermined scan (the value of the D / A converter data is incremented a predetermined number of times , and
When the wave number is the scan end frequency, for example, 3540 Hz
It is determined whether or not the predetermined scan has been reached ). If the predetermined scan has not been completed, the process returns to step S2.

In step S10, the interference intensity data stored in the RAM 3 is subjected to digital bandpass filtering, and in step S11, window processing is further performed to remove unnecessary band frequencies. In step S12, FFT processing is performed to perform interference intensity data. Is converted into distance information data, and displayed on the display device 4 in step S13.

By performing the operation described above,
The ultrasonic distance measuring device according to the present embodiment can accurately measure and display distances to a plurality of objects.

FIG. 7 is a block diagram showing the configuration of a laser beam distance measuring apparatus according to a second embodiment of the present invention.
Note that the same components as those in the first embodiment are described with the same names, and description thereof is omitted.

In this embodiment, the functions of the carrier oscillator and the transmitting means in the first embodiment are replaced by the laser diode 1.
8 is in charge. That is, the laser diode 1
When a predetermined drive current is supplied to the laser diode 8, the laser diode 18 oscillates at a constant optical frequency and emits laser light of a predetermined intensity (FIG. 8A). At this time, if the drive current is changed, the intensity of the laser light changes. Therefore, when the output of the VCO 8 (FIG. 8B) is input to the laser diode 18 through the current drive circuit 17, the laser diode 1
The output light 8 changes its intensity in proportion to the oscillation frequency of the VCO 8 (FIG. 8C).

The laser light output from the laser diode 18 is reflected by the object Ob and reflected by the photodiode 19.
Incident on the light receiving surface of. The output signal of the photodiode 19 (FIG. 8D) is converted into a voltage via the voltage output circuit 20, and is amplified to a predetermined voltage value by the amplifier 13 as in the first embodiment. input. And
Similar to the first embodiment, the mixer 14 performs homodyne detection with the reference oscillation signal from the VCO 8 to obtain an interference intensity signal. After that, the distance information data is obtained through the same processing as in the first embodiment.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be implemented in any manner unless the configuration described in the claims is changed. . For example, the display of the distance information may be performed digitally.

[0024]

As described above, the distance measuring method and apparatus according to the present invention measure distances to a plurality of objects.
In addition to this, all the components can be constituted only by electronic circuit components, so that the size and weight of the device can be reduced, the manufacturing cost can be reduced, and it can be widely applied in the industrial world.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a distance measuring device according to a first embodiment of the present invention.

FIGS. 2A to 2D are conceptual diagrams showing signal waveforms in the distance measuring device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a positional relationship between a distance measuring device and an object according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the frequency of the interference wave frequency and the output of the distance measuring device according to the first embodiment of the present invention.

FIG. 5 is a characteristic diagram illustrating a relationship between a distance and a relative intensity of the distance measuring device according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of the distance measuring device according to the first embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a distance measuring device according to a second embodiment of the present invention.

FIGS. 8A to 8D are conceptual diagrams showing signal waveforms in a distance measuring device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 ROM 3 RAM 4 Display device 5 D / A converter 6 A / D converter 7 Carrier oscillator 8 VCO 9 AM modulator 10 Transmitting means 10 'Resonant ultrasonic oscillator 11 Receiving means 11' Ultrasonic sensor 12 Envelope detector DESCRIPTION OF SYMBOLS 13 Amplifier 14 Mixer 15 RMS circuit 16 DC cut filter 17 Current drive circuit 18 Laser diode 19 Photodiode 20 Voltage output circuit Ob Object Ob1 object Ob2 unit

Continuation of front page (56) References JP-A-6-138231 (JP, A) JP-A-6-186337 (JP, A) JP-A-1-187485 (JP, A) JP-A-1-129181 (JP) JP-A-1-102387 (JP, A) JP-A-1-102386 (JP, A) JP-A-5-94783 (JP, U) JP-A-3-68090 (JP, U) (58) Surveyed field (Int.Cl. ⁶ , DB name) G01S 7/00-7/64 G01S 13/00-17/88 G01B 11/00

Claims (6)

(57) [Claims] An AM (Amplitude Modul) which modulates the frequency of a carrier signal continuously within one transmission cycle.
)) transmits a transmission wave generated by applying modulation or intensity modulation, receives a reflected wave from the target, and detects a distance to the target from a difference in interference intensity caused by a phase difference with the modulation signal. A distance measuring method. 2. The distance measuring method according to claim 1, wherein the AM-modulated transmission wave is an ultrasonic wave. 3. The distance measuring method according to claim 1, wherein the intensity-modulated transmission wave is a laser beam. 4. A first oscillating means for outputting a carrier signal, a second oscillating means capable of continuously changing an oscillating frequency within one transmission cycle, and an output signal of the first oscillating means for outputting the carrier signal. Transmitting means for performing AM modulation or intensity modulation with an output signal of the oscillating means and transmitting the same; receiving means for receiving a reflected wave of a transmission wave output from the transmitting means from a target; output of the receiving means Interference intensity detecting means for detecting an interference intensity caused by a phase difference between a signal and an output signal of the second oscillating means, and data converting means for converting an output of the interference intensity detecting means into distance information from the target. A distance measuring device comprising: 5. The distance measuring device according to claim 4, wherein the AM-modulated transmission wave is an ultrasonic wave. 6. The distance measuring apparatus according to claim 4, wherein the intensity-modulated transmission wave is a laser beam.