JP4619641B2 - Ultrasonic measuring device - Google Patents

Description

  The present invention is mounted on a moving body such as various vehicles and autonomous / mobile robots, and the distance (relative distance) between the moving body and surrounding objects, and the speed of the object relative to the moving body (relative speed). ).

  Conventionally, in the field of moving bodies such as vehicles represented by automobiles and autonomous / moving robots, in order to avoid collisions, an ultrasonic measuring device using an ultrasonic sensor is mounted on the moving body. Measuring the relative distance of a moving object such as a vehicle, a person, etc., or a stationary object such as a wall, guardrail, or power pole, and the relative speed of the object relative to the moving object Has been done.

  For example, in the case of a vehicle, it has been proposed to measure the relative distance and relative speed as described in the following (1) to (3) using an ultrasonic measurement device mounted on the host vehicle.

  (1) Utilizing the so-called Doppler effect of ultrasonic waves, ultrasonic waves are output from some elements of an ultrasonic transducer in which a plurality of piezoelectric elements are arranged, and reflected waves from a target object in front of the vehicle are Received multiple times by all the elements of the ultrasonic transducer, and measure the relative speed (vector motion speed) of the target object ahead of the vehicle from the time change of the Fourier transform result of the time-series received signal (for example, , See Patent Document 1).

  (2) An object in the so-called blind spot at the rear of the vehicle side is detected by transmission / reception of ultrasonic waves of an ultrasonic sensor, and the distance between the vehicle and the object is detected and measured from the transmission / reception time difference. Based on the analysis, the relative velocity of the object is detected and measured from the frequency difference between the frequency of the transmission wave and the frequency of the reception wave (see, for example, Patent Document 2).

  (3) The so-called back sonar and corner sonar are formed by the ultrasonic measuring device, the ultrasonic wave is output from the transducer (ultrasonic transducer) to the outside of the vehicle, and the obstacles around the vehicle are reflected. The wave is received by the transducer and subjected to fast Fourier transform, and after starting transmission, the distance between the vehicle and the obstacle is calculated and measured from the time until the transmission wave frequency component of the reflected wave exceeds the threshold (for example, , See Patent Document 3).

Also, in the field of vehicle collision avoidance, the millimeter wave in the GHz band is an electromagnetic wave that can be detected far away at the speed of light and has characteristics that are not affected by disturbances such as weather. A collision avoidance control is also performed by measuring a relative distance and a relative speed of an object ahead of the host vehicle by a pre-crash sensor using a sensor.
JP-A-8-292254 (paragraph numbers [0017]-[0021], FIG. 7) JP-A-8-324366 (paragraph numbers [0006], [0014], [0015], FIG. 4) Japanese Patent Laid-Open No. 2001-221848 (paragraph numbers [0036] and [0057], FIGS. 1 and 4)

  In general, since an ultrasonic sensor is a sound wave compared to radio waves such as a millimeter wave sensor, the detection speed is slow, the measurable range (distance) is limited to a so-called short-range range of several meters or less, There is a characteristic that it is easily affected by so-called reverberation and various environmental noises.

  In the case of the conventional apparatus (1) using this ultrasonic sensor, since the relative velocity cannot be measured unless the reflected wave is received a plurality of times, the measurement result is obtained in consideration of the above characteristics. Signal processing is extremely complicated to detect the situation where collision avoidance control and the like are performed from the change tendency of the measurement result obtained by repeatedly receiving reflected waves multiple times. There is a problem.

  For this reason, if processing is not performed at a very high speed, the time margin for executing collision avoidance control or the like based on the measurement result becomes extremely short, which is not practical, and the distance (relative distance) is measured separately. There are also problems that need to be done.

  In the case of the conventional device (2), both the relative distance and the relative velocity can be measured. The relative distance is measured by measuring the time required from the transmission of the ultrasonic wave to the reception of the reflected wave. In addition to signal processing of transmitted waves and received reflected waves, timing processing is required, the processing load on the circuit section is large, and both the relative distance and relative speed can be quickly achieved with a small and inexpensive configuration. There is a problem that cannot be measured.

  Further, in the case of the conventional device of (3), it is necessary to measure the relative distance by measuring the time required from the start of transmission until the transmission wave frequency component of the reflected wave exceeds the threshold. In addition to the wave signal processing, time measurement processing is required, and there is a problem similar to that of the device of (2), and the relative speed needs to be separately measured by the device of (1), for example. is there.

  Next, the pre-crush sensor formed using the conventional millimeter-wave sensor is a special sensor for electromagnetic waves, which is very expensive, and is applied to the millimeter-wave human body and other devices. Since the influence has not been sufficiently elucidated, it cannot be said that the configuration is optimal as a vehicle pre-crash sensor in which both price and safety are important.

  The ultrasonic sensor is also used for the back sonar and corner sonar, and is a mass-produced general-purpose sensor, so it is inexpensive and the ultrasonic wave has no influence on the human body. In this case, it is possible to measure both the relative distance and the relative speed as quickly as possible with a small and inexpensive configuration. It will be an important issue.

  The present invention is an ultrasonic measurement device mounted on a moving body such as a vehicle or an autonomous / mobile robot, and includes a distance (relative distance) between an object such as an obstacle around the moving body and the moving body, An object of the present invention is to make it possible to simultaneously measure the velocity (relative velocity) of an object with respect to a moving body by signal processing for one transmission and reception of ultrasonic waves, and to quickly measure with a small and inexpensive configuration.

In order to achieve the above-described object, an ultrasonic measurement device of the present invention is an ultrasonic measurement device mounted on a moving body, and includes a transmission unit that outputs an ultrasonic transmission wave to the outside of the moving body; A reception unit that receives a reflected wave of the transmission wave reflected by an object outside the moving body, a Fourier transform unit that performs FFT processing on at least the reception signal of the reception unit, and the transmission using the fundamental frequency wave as a first harmonic wave A distance between the moving object and the object is calculated from a normalized amplitude ratio of the p-th harmonic (p is an integer including 1) between the wave signal and the reception signal, and the signal of the transmission wave and the reception the q harmonics normalized with the signal (q is different from p integer) e Bei a calculating unit for calculating the relative velocity of the object from the frequency difference, the transmission wave is a pulse wave of the square wave The p-th harmonic is an odd-order harmonic (p is an odd number), wherein the q harmonics are harmonics even-order (q is an even number) (claim 1).

Next, the ultrasonic measurement apparatus of the present invention further includes a noise filter that removes unnecessary noise from the reception signal of the reception unit, and a display unit that displays the distance and relative velocity calculated by the calculation unit. It is also characterized by comprising (claims 2, 3 ).

The ultrasonic measuring apparatus of the present invention, the ultrasonic wave reception of the ultrasonic output 及 beauty receiver of the transmission unit may be performed by a single ultrasonic transducer for both transmission and reception (Claim 4), You may make it carry out with a separate ultrasonic transmitter and an ultrasonic receiver, respectively (Claim 5 ).

Furthermore , the ultrasonic measurement apparatus of the present invention is characterized in that the moving body is a vehicle, and the transmission unit outputs a transmission wave in front of the vehicle to form a pre-crash sensor (Claim 6 ). It is also characterized by being an autonomous and mobile robot (claim 7 ).

Next, in the ultrasonic measurement apparatus of the present invention, a plurality of transmission units and reception units are arranged on the moving body so as to expand the measurement range, and a Fourier transform unit and a calculation unit are connected to the transmission unit and the reception unit. The transmission waves of the transmission units of each set are ultrasonic waves having different odd-order p-th harmonics at different frequencies (claim 8 ).

First, according to the invention of claim 1, the transmission wave of the square wave output from the transmitting unit of the moving body to the front of the moving body is reflected by an object such as an obstacle outside the moving body, Ultrasonic waves in which nonlinear changes such as waveform distortion are caused by reflection are received as reflected waves by the receiving unit of the moving body.

Then, at least a harmonic component of the reception signal of the reception unit is detected by the FFT processing of the Fourier transform unit. At this time, the harmonic amplitude ratio of the known or received signal detected by the signal and FFT processing of the detected original transmission wave FFT processing is proportional to the distance between the object and the moving object (relative distance) changes Te, the frequency difference between the harmonics of the signal and the received signal of the transmitted wave varies in proportion to the relative speed of the object. Therefore, the calculating section, odd (p is an odd number) determined the relative distance from the amplitude ratio of the p harmonic of the signal and the received signal of the transmission wave, at the same time, even with the signal and the received signal of the transmitted wave next (q is an even number) may therefore be found the relative velocity of the the frequency difference between the q harmonics.

Thus, the relative distance of surrounding objects in front or the like of the moving body, a relative speed, without repeating the transmission and reception, in a single transmission and reception of ultrasonic waves, in a short time, as possible out to measure simultaneously.

  Therefore, it is possible to quickly measure both the relative distance and relative speed of an object such as an obstacle around a moving body with a small-scale configuration that transmits and receives inexpensive and safe ultrasonic waves and performs only signal processing. be able to.

Next , according to the invention of claim 2 , the noise filter can reduce and remove environmental noise, noise generated in the apparatus, and the like from the received signal of the receiving unit, and the object having a configuration resistant to noise. There is an advantage that the relative distance and the relative speed of can be measured.

Furthermore , according to the invention of claim 3 , the relative distance and the relative speed of the measurement result can be displayed on the display unit for notification and the like, which is practical.

Then, according to the invention of claim 4, the one ultrasonic transceiver to the ultrasonic receiver of the ultrasonic output 及 beauty receiver of the transmission unit is shared, miniaturization of a small number of parts becomes by device There are advantages to be envisioned.

Further, according to the invention of claim 5, since the ultrasonic output of the transmission unit and the ultrasonic reception of the reception unit are separately performed by the separate ultrasonic transmitter and ultrasonic receiver, respectively. There is an advantage that the setting and adjustment of the receiving direction can be freely performed separately for transmission and reception.

Further, according to the invention of claim 6, when the moving body is a vehicle, it is possible to form a pre-crash sensor transmission unit outputs a transmission wave to the forward vehicle, according to the invention of claim 7, The present invention can be applied to the measurement of the relative distance and the relative speed when the moving body is an autonomous / mobile robot.

Furthermore, according to the invention of claim 8, arranged a plurality of sets of transmitting unit and the receiving unit to the mobile, and outputs an ultrasonic wave of each set of the transmitter or we different frequencies, each set of receiver Received signals can be processed by each set of Fourier transform units and calculation units, and the relative distance and relative speed can be measured for each set. The relative distance and relative speed can be measured simultaneously.

  Next, in order to describe the present invention in more detail, the embodiment will be described in detail with reference to FIGS.

<< One Embodiment >>
First, an embodiment in which a pre-crash sensor is formed by providing a set of transmission and reception units to a vehicle as a moving body will be described in detail with reference to FIGS.

  1 is a plan view of a vehicle 1 as a moving body, FIG. 2 is a block diagram of an ultrasonic measurement device mounted on the vehicle 1, FIG. 3 is an explanatory diagram of the transmission wave, and FIG. 4 is a frequency of the transmission wave is a square wave. FIG. 5 is an example of an FFT spectrum of a signal when a transmission wave is a square-wave frequency modulation pulse wave in the case of a modulated pulse wave.

  6 is a waveform diagram of the received signal of FIG. 1, FIGS. 7 and 8 are waveform diagrams of the Fourier cosine coefficient term and the Fourier sine coefficient term, and FIGS. 9 and 10 are the amplitudes of the respective harmonics of the received signal. It is a characteristic figure and an angular velocity characteristic figure.

  Further, FIG. 11 shows the FFT spectrum of the signal of the transmission wave and the reception signal, FIGS. 12, 13, and 14 show the spectra of the odd-order reception harmonics at the relative distances of 24 cm, 50 cm, and 100 cm in FIG. FIG. 6 is a relationship diagram between the distance and amplitude of first and third harmonics of a received signal. However, these are naturally cases in which the transmission wave is a square-wave frequency-modulated pulse wave, and is an example calculated by paying attention only to the amplitude for odd harmonic components and only the frequency for even harmonic components. FIG. 16 is a flowchart for explaining the operation of FIG.

  In the vehicle 1 of FIG. 1 as a moving body, an ultrasonic transmission / reception unit 2 outputs an ultrasonic transmission wave forward and receives a reflected wave at the front center of a front bumper, a bonnet or the like. The unit 2 is provided, for example, with one ultrasonic transmitter / receiver shared by a general-purpose ultrasonic sensor also used for back sonar and corner sonar, or a separate ultrasonic transmitter and ultrasonic receiver. Formed by a vessel.

  When the transmission / reception unit 2 is formed by a single ultrasonic transmitter / receiver, the transmitter / receiver is shared by the ultrasonic output and the ultrasonic reception, so that the number of parts is reduced, and the apparatus is inexpensive and compact. There are advantages.

  When the transmission / reception unit 2 is formed by separate ultrasonic transmitters and ultrasonic receivers, the installation position and angle of the ultrasonic transmitter and ultrasonic receiver are individually set and adjusted, There is an advantage that sound wave transmission, reception direction setting, adjustment and the like can be freely performed separately for transmission and reception.

  The ultrasonic transmitter / receiver, the ultrasonic transmitter, and the ultrasonic receiver of the transmission / reception unit 2 are formed using an ultrasonic transducer, a resonance horn, and the like in the same manner as a known ultrasonic sensor.

  Next, the ultrasonic measurement device of the vehicle 1 including the transmission / reception unit 2 is configured as shown in FIG. 2, and the transmission unit 3 includes a transmission output unit 30 and an oscillation circuit 31 formed by the transmission / reception unit 3.

  The oscillation circuit 31 is a hardware or software digital oscillation circuit, and generates an ultrasonic signal.

The ultrasonic signals, in consideration of the simplification of the Fourier analysis processing discussed later, Ri signal der square wave that includes only odd-order harmonics, further, in this embodiment, the environmental noise to improve the reception sensitivity effect equal to (effect of disturbance) so as not receiving as much as possible, the frequency modulated pulse wave signal of the square wave, i.e., a signal of the frequency modulated pulse wave.

Then, in order to repeat the measurement by generating a square-wave frequency-modulated pulse wave signal for each set pulse interval, the oscillation circuit 31 is controlled by , for example, a well-known digital control of a pulse frequency modulation method (PFM method). , reading the set waveform data, based on a combination processing of pulse code, the each pulse interval, for example, the center frequency to generate the signal of the frequency modulated pulse wave form waveform towards 40 KHz.

  The transmission output unit 30 generates an ultrasonic transmission wave of the frequency-modulated pulse wave by the vibration of the ultrasonic transducer based on the signal of the frequency-modulated pulse wave and emits it forward.

  2 includes a received wave input unit 40, a first amplifier circuit 41, a noise filter 42, and a second amplifier circuit 43.

  The received wave input unit 40 receives a reflected wave generated by reflecting the transmitted wave by an object such as a preceding vehicle ahead of the vehicle 1, and outputs the received signal of the electric signal to the first amplifier circuit 41. The first amplifier circuit 41 preamplifies the reception signal of the reception wave input unit 40.

  Further, the noise filter 42 is a digital filter formed by, for example, a Schmitt trigger circuit, an AND circuit, an OR circuit, a NAND circuit, or the like of a logic integrated circuit (logic IC) element. Noise such as reverberation and environmental noise, and internal noise generated in the measuring apparatus are removed.

  Specifically, the noise filter 42 uses a correlation operation that refers to the transmission wave, for example, in the same manner as the known noise reduction processing of this type of frequency-modulated pulse wave, except for the harmonic component of the reflected wave from the received signal. The unnecessary frequency component is reduced and the unnecessary noise is removed.

  In this case, the digital filter using the logic IC element has an advantage that fine noise removal can be performed by ON / OFF switching of each logic circuit.

  Needless to say, the noise filter 42 may be various analog filters or digital filters for removing the unnecessary noise.

  Then, the second amplifier circuit 43 outputs and amplifies the reception signal from which unnecessary noise has been removed by the noise filter 42.

  Next, the Fourier transform unit 5 and the calculation unit 6 in FIG. 2 are formed by software processing of a microcomputer.

  Then, in order to detect the nonlinear response of the ultrasonic wave, the Fourier transform unit 5 receives, for example, the reception signal of each pulse interval from the second reception circuit 43 of the reception unit 4 every time, for example, the transmission unit 3 Fast Fourier transform (FFT) processing is performed on each of the transmission wave signal and reception signal in the section input from the oscillation circuit 31, and the transmission wave signal and the reflection wave reception signal are subjected to Fourier analysis processing. Therefore, each harmonic is detected with the fundamental frequency wave as the first harmonic.

  Since the harmonic component of the transmitted wave signal is known, the known harmonic component may be used as the detection component without performing the Fourier analysis process. In this case, the Fourier transform unit 5 Simplifies the process.

By the way, the Fourier series formula h (t) relating to the time t is generally represented by the following formula <1>. In the formula, a ₀ , a _n , and b _n are constants, and ω is an angular velocity of ω = 2π / T (T is a period).

  Further, when the above formula <1> is Fourier transformed by the following formula <2>, t is eliminated and becomes a function of frequency.

  Then, the Fourier transform unit 5 decomposes and analyzes each of the transmission wave and the reflected wave in the time domain into a waveform in the frequency domain by FFT processing, and detects each harmonic.

  At this time, the transmission wave signal input to the Fourier transform unit 5 is, for example, a square wave signal having no waveform distortion shown in FIG. 3, and the Fourier series expression h (t) of this signal is given by It is represented by the formula <3>.

  This expression <3> indicates that the square wave transmission wave is composed of a composite waveform of odd-order harmonics of 1, 3, 5,... As shown in FIG.

The normalized Fourier spectrum of the 40 kHz transmission wave signal is, for example, as shown in the actual measurement example of FIG. 5 and includes only odd-order harmonics.

  On the other hand, the received signal of FIG. 6, for example, input to the Fourier transform unit 5 has a waveform in which the reflected wave is distorted nonlinearly from the square wave. Note that intermittent K (t1), K (t2),... In FIG. 6 are each pulse interval, and an interval between each pulse interval is a calculation period.

Therefore, the received signal of each pulse section includes odd-order harmonics of 1, 3, 5,... And even-order harmonics of 2, 4, 6,. As shown in the waveform diagrams up to the third order of FIGS. 7 and 8, for example, the Fourier cosine coefficient term and the Fourier sine coefficient term of the trigonometric series are all first, third order (odd order) and second order (even order). ), And the amplitude Cn (= √ (an ² + bn ² )) and angular velocity (nω) of each harmonic are as shown in FIGS. 9 and 10, for example.

  Then, the distance between the vehicle 1 and the object in front is changed to 24 cm, 50 cm, and 100 cm (1 m), and the received signal is fast Fourier transformed by the Fourier transform unit 5, and each harmonic detected by this transform is calculated by the computation unit 6. When the normalized Fourier spectrum was obtained, the actual measurement result of FIG. 11 was obtained.

  In FIG. 11, a cross indicates a received signal spectrum (reception spectrum) at a relative distance of 24 cm, a closed circle indicates a relative distance of 50 cm, a open circle indicates a relative distance of 100 cm, and a closed circle indicates a spectrum of a transmission wave.

Incidentally, in this embodiment, as described later, determined Me a distance from said amplitude ratio rV of odd-order harmonics of the signal and the received signal of the transmission wave, the frequency difference between the even-order harmonics of the two signals for Mel determined the relative velocity of the delta] f, the Fourier transform unit 5, the process of the arithmetic unit 6, and observes only the amplitude variation due to the distance for the odd-order harmonics (the vertical change of the FFT results), the even-order For harmonics, only frequency shift (horizontal change of FFT result) is observed.

  Therefore, in FIG. 11, the odd-order first, third, and fifth harmonics do not show a frequency shift like the even-order second and fourth harmonics, and the even-order second, The fourth harmonic does not show the difference in amplitude as in the first, third, and fifth harmonics of the odd order, but in reality, there is an amplitude difference and a frequency shift in all the harmonics. It appears and the tendency is the same as in FIG.

  And the reception spectrum according to the relative distance of the odd-order harmonics (first, third, and fifth harmonics) in FIG. 11 is as shown in FIGS. 12, 13, and 14, for example, The amplitude characteristics with respect to the relative distance between the first harmonic and the third harmonic are as shown by solid lines a and b in FIG.

From these results, the longer the distance (relative distance R 1 ) between the vehicle 1 that is a moving body and an object such as a preceding vehicle ahead of it, the smaller the amplitude of each harmonic of the received signal, the same tendency It has been found that the relative distance R can be measured from the amplitude ratio rV of the harmonics of the same order (frequency) between the transmitted wave signal and the received signal.

Further, according to the relative velocity ν of said object relative to the car both 1, the frequency difference between the harmonics of the signal and the received signal of the transmission wave is turned into strange, it has also been found to be able to measure the relative velocity ν of said from the frequency difference .

Furthermore, the sound velocity c, and the center frequency of the number of modulation frequency f0, Then before Symbol a frequency difference [delta] f, the relative velocity [nu, obtained formula <4> or these following.

ν = (c / (2 × f0)) × δf formula <4>

Then, the amplitude ratio rV, by Rukoto calculated frequency difference δf from different appropriate harmonic, relative distance R to minimize the processing load of the computer, the simultaneous measurement of the relative velocity ν performed.

Meanwhile, when the transmission wave is a square wave, only odd-order harmonics are present in the transmitted wave, amplitude ratio rV is calculated from the odd-order harmonics, the frequency difference δf is Ru determined from even-order harmonics. At this time, as is clear from FIG. 11 and the like, the lower the harmonic wave of order greater amplitude, since the amplitude ratio rV is clarified, the amplitude ratio rV is Ru determined from the first harmonic.

That is, (integer including the p 1) p-th harmonic harmonics seeking amplitude ratio rV, when the high harmonics that seek frequency difference δf and the q harmonic, when the transmission wave is a square wave, The p-th harmonic is limited to odd-order harmonics (preferably the first harmonic), and the q-th harmonic is an even-order harmonic.

In the case of this embodiment the transmitted wave is a square wave, every time the reception signal of the reflected wave of each pulse period is inputted to the Fourier transform unit 5, by a Fourier analysis of the FFT, the signal of the transmission wave and N times time-shifted data (data whose frequency changes with time) y (1), y (2),..., Y (N) are Fourier-transformed from the first harmonic to the received signal of the reflected wave. Frequency data f (1), f (2),..., F (X) of X harmonics are obtained to obtain a Fourier spectrum.

  At this time, only the odd-order harmonic frequency data f (1), f (3),... Are obtained for the transmission wave signal which is a square wave, and the received signal of the reflected wave including nonlinear distortion information is obtained. , F (1), f (2),..., F (X) are obtained for odd-order and even-order harmonics.

Next, the harmonic wave of the Fourier spectrum of the transmission wave signal and the reception signal is normalized by the same reference by the calculation unit 6, and the frequency data of the odd harmonics normalized by both signals, for example, data f ( the amplitude comparison of 1), the p harmonics at which to obtain an amplitude ratio rV of the first harmonic to measure the corresponding relative distance R, at the same time, even-order harmonics of the frequency data normalized for both signals For example, the frequency difference δf of the second harmonic that is the q-th harmonic is obtained by calculating the frequency difference of the data f (2), and the relative speed ν is obtained from the calculation of the formula <4> and measured.

Therefore, every time the reception signal is obtained, a signal of the transmission wave at that time, by calculation of based rather a single signal processing and reception signal, the relative distance R and the relative velocity ν is simultaneously measured, this time, If the frequency of the received signal shifts to the left and the frequency difference δf decreases, the relative distance R and the relative speed ν of the object ahead of the vehicle 1 are measured, and the frequency of the received signal shifts to the right and the frequency difference If δf increases, the relative distance R and the relative speed ν of the object in front of the vehicle 1 are measured.

  Then, the measured data of the relative distance R and the relative speed ν is supplied as an output of the pre-crash sensor, for example, to an ECU for collision avoidance control (not shown), and control necessary for collision avoidance is performed by this ECU.

  Further, the measured relative distance R and relative speed ν are displayed on the display unit 7 in the vehicle as warnings with numerical characters and figures.

  Note that the above-described series of processing is performed, for example, according to the operation procedure of the flowchart of steps S1 to S7 in FIG. 16, and a received signal is obtained within a set minute specified time by emission of a transmission wave (step S1). If so (step S2), a Fourier analysis process is performed on the signal of the transmission wave and the reception signal (step S3), the amplitude ratio rV and the frequency difference δf are detected (step S4), and the result is displayed (step S5). On the other hand, when the received signal is not obtained within the specified time, there is no object such as a preceding vehicle in front and no reflected wave is obtained, so the process goes from step S2 to step S7 through step S6. The process proceeds to reset the display on the display unit 7 to the initial state indicating no measurement.

  As described above, in the case of this embodiment, the relative distance R and the relative velocity ν of an object such as a preceding vehicle in front of the vehicle 1 and a wall can be reduced by one transmission / reception of ultrasonic waves without repeating transmission / reception. It is possible to measure at the same time, and at that time, it is only necessary to perform signal processing of the transmitted wave and its reflected wave, and it is not necessary to perform time measurement processing from the transmission wave emission until reception of the reflected wave. Due to the scale and low cost configuration, the measurement of each pulse section can be completed quickly. When this measurement is repeated and collision avoidance control is required based on the measurement results, a sufficient time margin should be secured. Can do.

Since having a Bruno Izufuiruta 42, more resistant to noise, the stability of the measurement accuracy and measurement is extremely improved.

  In addition, the amplitude ratio rV is obtained from the odd-order harmonics, the frequency difference δf is obtained from the even-order harmonics, and the harmonic that obtains the amplitude ratio rV is different from the harmonic that obtains the frequency difference δf. And the relative distance R and the relative velocity ν can be measured simultaneously.

  Therefore, the pre-crash sensor of the vehicle 1 can be realized with an inexpensive and highly safe configuration for measuring ultrasonic waves.

<< Other Embodiments >>
Next, another embodiment will be described with reference to a plan view of the vehicle 1 in FIG.

  In the case of this embodiment, as shown in FIG. 17, a plurality of transmission / reception units 2 forming transmission / reception units 3, 4 are arranged at a plurality of locations at the front end of the vehicle 1 so as to expand the measurement range. To do.

  Therefore, an object or the like popping out from the side can be captured by any of the transmission / reception units 2 as an object ahead of the measurement target.

  In this case, at least the Fourier transform unit 5 and the calculation unit 6 of FIG. 2 are sent and provided for each set of the reception units 3 and 4, and the calculation and detection of the amplitude ratio rV and the frequency difference δf of each set are performed simultaneously. preferable.

  The present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made without departing from the spirit of the present invention.

For example , the transmission / reception units 3 and 4 may be formed separately by separate ultrasonic transmitters and ultrasonic receivers. In this case, the installation positions and the installation angles of the transmission unit 3 and the reception unit 4 are adjusted. There is an advantage that can be performed individually.

  Further, the number of transmission / reception units 3 and 4 and the positions to be provided may be any, and may be set appropriately according to the use of the measurement results. For example, the transmission / reception units 3 and 4 are combined. Alternatively, the relative distance R and the relative speed ν in all directions may be measured by arranging the movable body around the entire circumference (entire circumference) or part of the movable body at appropriate intervals.

  The vehicle as the moving body is not limited to a so-called automobile, and may be various vehicles such as an automatic guided vehicle at a golf course. Further, the moving body is an autonomous / moving robot other than the vehicle. Of course, various industrial and consumer devices may be used.

  By the way, in order to reduce the number of equipment parts of the moving body, for example, in the vehicle 1 of FIG. .

It is a top view of the vehicle of one embodiment. It is a block diagram of the ultrasonic measuring device mounted in the vehicle of FIG. It is explanatory drawing of the transmission wave of FIG. It is explanatory drawing of the harmonic contained in the transmission wave of FIG. It is an example of the FFT spectrum of the signal of the transmission wave of FIG. It is a wave form diagram of the received signal of FIG. It is a wave form diagram of the Fourier cosine coefficient term of the received signal of FIG. It is a wave form diagram of the Fourier sine coefficient term of the received signal of FIG. It is an amplitude characteristic view of each harmonic of the received signal of FIG. It is an angular velocity characteristic figure of each harmonic of the received signal of FIG. 2 is an FFT spectrum of a transmission wave signal and a reception signal in FIG. 1. 12 is a spectrum of odd-order received harmonics at a relative distance of 24 cm in FIG. 12 is a spectrum of odd-order received harmonics at a relative distance of 50 cm in FIG. 12 is a spectrum of odd-order received harmonics at a relative distance of 100 cm in FIG. FIG. 3 is a relationship diagram between distances and amplitudes of first and third harmonics of the received signal in FIG. 1. It is a flowchart for operation | movement description of FIG. It is a top view of the vehicle of other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 3 Transmitting part 4 Receiving part 5 Fourier transform part 6 Calculation part 7 Display part

Claims (8)

An ultrasonic measurement device mounted on a moving body,
A transmitter that outputs an ultrasonic transmission wave to the outside of the moving body;
A receiving unit that receives a reflected wave of the transmission wave reflected by an object outside the moving body;
A Fourier transform unit that performs at least FFT processing on the reception signal of the reception unit;
The distance between the moving body and the object is determined from the amplitude ratio of the normalized p-th harmonic (p is an integer including 1) of the signal of the transmission wave and the reception signal, where the fundamental frequency wave is the first harmonic. An arithmetic unit that calculates the relative velocity of the object from the frequency difference of the standardized qth harmonic (q is an integer different from p) between the signal of the transmission wave and the reception signal;
The transmission wave is a square pulse wave, the p-th harmonic is an odd-order harmonic (p is an odd number), and the q-th harmonic is an even-order harmonic (q is an even number). An ultrasonic measurement device characterized by that.   The ultrasonic measurement apparatus according to claim 1, further comprising a noise filter that removes unnecessary noise from the reception signal of the reception unit.   The ultrasonic measurement apparatus according to claim 1, further comprising a display unit that displays a distance and a relative speed calculated by the calculation unit.   The ultrasonic measurement apparatus according to claim 1, wherein the ultrasonic output of the transmission unit and the ultrasonic reception of the reception unit are performed by a single ultrasonic transmitter / receiver. .   The ultrasonic output according to any one of claims 1 to 3, wherein the ultrasonic output of the transmission unit and the ultrasonic reception of the reception unit are performed by separate ultrasonic transmitters and ultrasonic receivers, respectively. Sound wave measuring device.   The ultrasonic measurement apparatus according to claim 1, wherein the moving body is a vehicle, and the transmission unit outputs a transmission wave in front of the vehicle to form a pre-crash sensor. Ultrasonic measuring apparatus according to any one of claims 1 to 5, moving body is characterized in that it is a self-moving type robot. In the ultrasonic measuring device according to any one of claims 1 to 7,
A plurality of transmission units and reception units are arranged on the moving body so as to expand the measurement range, and a Fourier transform unit and a calculation unit are provided for each set of the transmission unit and the reception unit,
The ultrasonic wave measuring apparatus according to claim 1, wherein the transmission waves of the transmission units of the sets are ultrasonic waves having different frequencies of the odd-order p-th harmonics.

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