JPH0755933A - On-vehicle ultrasonic measuring instrument - Google Patents

Abstract

PURPOSE:To accurately detect the speed of a vehicle by transmitting ultrasonic waves at a prescribed dip angle so that the ultrasonic waves can be reflected from the intersection of the vertical center line of a wheel, side face of the tire, and road surface and its vicinity. CONSTITUTION:A left-side ultrasonic transmitter-receiver TRL is fitted to the bottom of a vehicle in parallel with the direction opposite to the advancing direction of the vehicle at an angle (dip phi) of 45 deg. against the horizontal plane and an angle (deflection theta) of 30 deg. from the advancing direction of the vehicle 100 toward the inside of a left tire TyL. The transmitter-receiver TRL transmits ultrasonic vibrations to the shoulder section of the title TyL and road surface and their vicinity and receive reflected waves of the vibrations from the outermost high-speed part of the tire TyL, and road surface. The speed VL of the vehicle 100 is obtained by performing arithmetic operation on the reflected signals. Similarly, the speed VR of the vehicle 100 is obtained by means of a right-side ultrasonic transmitter-receiver TRR. The running speed of the vehicle can be obtained from V=(VR+VL)/2. Even when the vehicle runs on a wet asphalt roar or road surface covered with water, the measurement is hardly affected by road surface waves and sprays of the water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a measuring device that uses various speed information such as a navigation system, a vehicle speed detecting device, a yaw angle, and a yaw rate detecting device, and more particularly to a vehicle-mounted ultrasonic measuring device that uses ultrasonic waves loaded in a vehicle.

[0002]

2. Description of the Related Art As a velocity measuring device using ultrasonic waves of this type, there is a technique disclosed in Japanese Utility Model Laid-Open No. 57-68574. The technology disclosed in this publication continuously transmits ultrasonic waves from a separate wave transmitter, continuously receives the waves received by reflecting from the reflector, and calculates the difference between the waves transmitted and received. It detects a certain Doppler frequency, and is a well-known technique at present.

Further, as a velocity measuring device using this kind of ultrasonic wave, there is a technique disclosed in JP-A-59-203973. The technique disclosed in this publication has a wave transmitter and a wave receiver which are separate bodies, as in the case of the above-mentioned publication, and in particular, the number of wave receivers is two, and vertical vibration of the vehicle body, nose up, This is to reduce the error due to nose down.

As a speed measuring device using this kind of ultrasonic wave, there is a technique disclosed in Japanese Patent Laid-Open No. 58-39971. The technology disclosed in this publication transmits ultrasonic waves in a pulse shape, opens a reception gate corresponding to the pulse width at the time of reflection and reception, and measures the time of a predetermined wavelength of the received wave. , The Doppler shift amount is obtained and the vehicle speed is measured.

Further, as a vehicle-mounted ultrasonic measuring device of this type, there is a technique disclosed in Japanese Patent Laid-Open No. 3-269388.

According to this technique, ultrasonic waves are radiated from a wave transmitter / receiver to a road surface in the front or back direction of a vehicle at a predetermined depression angle.
The time from the received signal of the emitted ultrasonic waves and the reflected wave of the road surface projection to the projection is measured, and the signal level of the reflected wave of the road surface projection is compared with a predetermined threshold value, and the road surface projection in front of the vehicle is compared. The presence or absence of such a thing and its size are detected. And
The vehicle speed is detected based on the obtained Doppler frequency by detecting the vehicle height from the linear distance and the radiation angle of the ultrasonic wave when the reflected wave returns from the road surface.

That is, one of the in-vehicle ultrasonic measuring devices shown in FIG.
As shown in the operation principle diagram when transmitting and receiving by one ultrasonic wave transmitter / receiver TR, the distance until the road surface is radiated by ultrasonic waves is L [m], and the height is H [m] ], And the radiation angle (depression angle) is φ degrees, then L = H / sin φ (1)

Loss due to propagation distance at this time Loos
Is Loos = (diffusion loss) + (propagation loss) = 20 · log (2 · L) + 2 · L · α [dB] ··· (2) where α: damping constant, for example, α100KHz = 2.1 [DB / m] α200KHz = 8.5 [dB / m]

On the other hand, when the ultrasonic beam width θ is narrowed, the energy is concentrated in the transmitted wave, so that the signal component S increases. Moreover, the S / N for the isotropic noise is improved in the received wave.

The total transmission / reception gain G is G = (transmission gain) × (reception gain) = {10 · log (γ / θ ² )} × 2 (3) where γ Is γ = 3.4 × 1 if the beam is rotationally symmetric
It is 0 ⁴ .

It should be noted that, in the operation principle diagram of the vehicle-mounted ultrasonic measuring device of FIG. 14, an ultrasonic wave having a frequency f [Hz] is intermittently radiated to the road surface, and the received frequency fo = f−df [Hz]. The Doppler frequency df [Hz] is calculated from df = 2f (V / 3.6) cosφ / C [Hz] ··· (4) where V: vehicle speed [Km / h] C: sound speed It becomes [m / s].

Particularly, in the technique disclosed in the above publication, ultrasonic waves are radiated with an equal radiation angle in the front-back direction of the vehicle body, and the Doppler frequency of the received signal of each reflected wave is detected,
By obtaining the Doppler frequency of the difference, the vehicle speed at which the vertical speed component of the vehicle body is canceled is detected. In addition, the vehicle height is determined by measuring the arrival time.

In this way, the protrusions and the like on the front road surface during traveling of the vehicle are detected using the ultrasonic waves, and the vehicle height and vehicle speed are also detected.

[0014]

However, in the technique disclosed in the above publication, the vehicle height is detected from the linear distance and the radiation angle of the ultrasonic wave when the reflected wave returns from the road surface, and the obtained Doppler frequency is also detected. To detect the vehicle speed, or
Ultrasonic waves are emitted with the same emission angle in the front-back direction of the vehicle body, the Doppler frequency of the received signal of each reflected wave is detected, the Doppler frequency of the difference is found, and the vertical velocity component of the vehicle body is canceled. It detects the vehicle speed.

Particularly, in the technique disclosed in Japanese Patent Laid-Open No. 59-203973, there is a method of using a rut to obtain reflection from a road surface in a state where road pebbles, snow and the like are squeezed by the load of wheels. It is disclosed.

However, the reflected wave itself is small on the submerged surface of the road, etc., and the vehicle speed accuracy is significantly reduced. When the road surface is wet due to rain, etc., water droplets are generated in the direction of the centrifugal force of the tire on the so-called submerged surface, and the Doppler frequency of the received signal of the reflected wave is detected. Cannot be measured. Also, on the submerged surface,
Road surface waves are generated in front of the traveling direction of the tires of the vehicle and may be affected by the reflection thereof or may not be affected by the reflection, which may cause malfunction.

Therefore, an object of the present invention is to provide a vehicle-mounted ultrasonic measuring device capable of accurately detecting the speed of a vehicle using ultrasonic waves.

[0018]

According to a first aspect of the present invention, there is provided an in-vehicle ultrasonic measuring device which transmits ultrasonic waves to a wheel with a predetermined depression angle inclination, and which transmits the ultrasonic wave to a vertical center line of the wheel and a side surface of the tire. A wheel speed calculation means for calculating the rotation speed of the wheel from the Doppler frequency of the ultrasonic wave transmitter / receiver that receives the reflected wave with its peripheral part centering on the intersection with the contact line with the road surface as the reflection point, and the wheel The speed calculation means calculates the speed from the rotation speed of the wheel calculated by the speed calculation means.

According to a second aspect of the present invention, there is provided a vehicle-mounted ultrasonic wave measuring device which transmits ultrasonic waves to the left and right wheels with a predetermined depression angle inclination, so that the vertical center line of the wheel contacts the side surface of the tire and the road surface. Around the intersection with the line as a reflection point,
Wheel speed calculation means for calculating the average rotation speed of the left and right wheels from the Doppler frequency of the ultrasonic wave transmitter / receiver that receives the reflected wave, and speed calculation for calculating the speed from the rotation speed of the wheels calculated by the wheel speed calculation means And means.

[0020]

According to the first aspect of the invention, ultrasonic waves are transmitted to the wheel with a predetermined depression angle inclination, and the ultrasonic wave is transmitted around the intersection of the vertical center line of the wheel and the contact line between the side surface of the tire and the road surface. The wheel speed calculation means calculates the wheel rotation speed from the Doppler frequency of the ultrasonic wave transmitter / receiver that receives the reflected wave at the peripheral part, and the speed is calculated from the wheel rotation speed calculated by the wheel speed calculation means. By calculating with the speed calculation means, the rotation speed of the wheel can be detected without being affected by water splashes and surface waves on the road surface.

In the second aspect, ultrasonic waves are transmitted to the left and right wheels with a predetermined depression angle gradient, and the center of the intersection of the vertical center line of the wheels and the contact line between the side surface of the tire and the road surface. The peripheral speed of the wheel is calculated from the Doppler frequency of the ultrasonic wave transmitter / receiver that receives the reflected wave and the peripheral speed is calculated from the wheel speed calculated by the wheel speed calculation means. Is calculated by the speed calculation means, the rotational speed of the wheel can be detected without being affected by water droplets and surface waves on the road surface. Further, the left and right wheel speeds independent of the left and right wheels can be detected, and the running state of the vehicle can be detected.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An on-vehicle ultrasonic measuring device according to an embodiment of the present invention will be described below.

<Basic Principle> FIG. 1 is an explanatory view of a cross section showing the structure of a tire. FIG. 2 is an explanatory diagram of the basic principle of the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention.

In FIG. 1, a tire Ty generally has a tread portion T1 which has a groove formed in a predetermined pattern and comes into contact with a road, a bead portion T4 attached to a rim, and sidewall portions T3 located on the left and right side surfaces. , A shoulder portion T2 located on both shoulders between the tread portion T1 and the sidewall portion T3, which constitutes one element of the wheel.

In FIG. 2, the depression angle is set to 45 degrees with respect to the horizontal plane parallel to the traveling direction of the vehicle 100, and the vehicle 10
The ultrasonic transmitter / receiver TR installed at the bottom of the vehicle body of 0 is 200
Ultrasonic vibration in the [KHz] band with a predetermined ultrasonic beam width, centered on the intersection of the vertical center line of the wheel (Y-Y line) and the contact line of the side surface of the tire Ty and the road surface (XX line). To transmit a wave near the shoulder portion T2 of the peripheral portion and the shoulder portion T2 of the sidewall portion T3 and receive the reflected wave, and obtain a velocity V parallel to the traveling direction of the vehicle 100. Is.

The ultrasonic wave transmitter / receiver TR is molded and integrated with each base member made of synthetic resin as a mounting base.

Here, the vehicle speed V in the traveling direction of the vehicle 100
Is the vehicle speed V = Vo / (1-k) where k is the tire speed Vo and the tire slip ratio is k. Since k can be approximated to 0 except during braking, it can be considered that V≈Vo (5).

Further, the distance and the acceleration can be calculated by integrating and differentiating the vehicle speed V.

3 to 5 are explanatory views showing the positional relationship of the ultrasonic transmitter / receiver TR of the ultrasonic measuring device for vehicle according to the embodiment of the present invention. FIG. 3 shows wet asphalt (soft asphalt) by the tire Ty. ) Is an explanatory plan view showing the condition of the road surface wave, FIG. 4 is an explanatory front view showing the condition of the road surface wave of the wet asphalt by the tire Ty, and FIG. 5 is an ultrasonic transmission / reception in the in-vehicle ultrasonic measurement device of this embodiment. Wave T
It is explanatory drawing which shows the arrangement | positioning positional relationship of R.

In FIG. 3, a road surface wave LW is generated on the wet asphalt WA in front of the tire Ty under the load of the vehicle as the vehicle advances. This road wave LW
Appears as a water surface wave in the case of flooded road surface as in the case of wet asphalt WA. However, even in the case of wet asphalt WA and submerged road surface, both sides in the vicinity of the intersection of the vertical center line (YY line) at the bottom of the tire Ty and the contact line (XX line) between the side surface of the tire Ty and the road surface. On the side W0, the influence of the road surface wave LW is minimized. Further, even when water is sprayed on the tire Ty when traveling on a submerged road surface, the lowermost side W0 of the tire Ty has generated road surface waves LW and water spray before reaching the side,
The effects of water waves and splashes are minimized.

Therefore, as shown in FIGS. 4 and 5, with the ultrasonic beam width α, the vertical center line (Y
-Y line), the contact line between the side surface of the tire Ty and the road surface (XX)
The wave is transmitted to the shoulder portion T2 near the intersection with the line) and the side wall portion T3 near the shoulder portion T2, and the reflection point αH is used to increase the Doppler frequency obtained from the outermost high speed portion of the tire Ty. can do. Therefore, the change in the Doppler frequency due to the change in the vehicle speed can be increased, and the vehicle speed accuracy can be increased accordingly.

Further, like the ultrasonic beam width β, near the intersection of the lowermost vertical center line (Y-Y line) of the tire Ty and the contact line (XX line) between the side surface of the tire Ty and the road surface. It is possible to increase the Doppler frequency obtained by transmitting the ultrasonic wave to the vicinity of the shoulder portion T2 of the tire and the road surface, and setting the outermost high-speed portion of the tire Ty and the road surface to the reflection point βHV of the ultrasonic beam. it can. Further, regardless of whether it is a wet asphalt WA road surface or a flooded road surface, the lowermost side W0 of the tire Ty is minimally affected by the road surface wave LW and the tire Ty when traveling on a flooded road surface. Even in the case of water droplets, the water drops are generated on both side W0 of the lowermost part of the tire Ty until reaching them, so that the influence of water waves and water droplets is minimized. Therefore, the change in the Doppler frequency due to the change in vehicle speed can be increased, the influence of road surface waves and water droplets can be eliminated, and the vehicle speed accuracy can be increased accordingly.

Then, like the ultrasonic beam width γ, the lowermost vertical center line (Y-Y line) of the tire Ty and the tire Ty.
Side W0 of the contact surface with the road surface near the intersection of the contact line (XX line) between the side surface of the tire and the road surface, that is, the vicinity of the contact surface between the road surface and the lower portion passing through the center line of the tire Ty, By setting that point as the reflection point γ V, the influence of the road surface wave LW is minimal on both sides W0 at the bottom of the tire Ty regardless of whether it is a wet asphalt WA road surface or a flooded road surface. Even when water is sprayed on the tire Ty when traveling on the road surface, water drops have been generated on both sides W0 at the lowermost part of the tire Ty before reaching them, so the influence of water waves and water spray is minimal. Become. Therefore, the change of the Doppler frequency due to the change of the vehicle speed can be increased, the influence of the road surface waves and the water droplets is small, and the vehicle speed accuracy can be increased accordingly.

FIG. 6 is an explanatory view of the basic principle of detecting a vehicle speed, a yaw rate and the like using the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention.

In FIG. 6, the depression angle φ is set to 45 degrees with respect to the horizontal plane parallel to the direction opposite to the traveling direction of the vehicle 100, and inside the tires Ty of the vehicle 100 with respect to the straight traveling position of the vehicle 100. In the present embodiment, the left ultrasonic transducer TRL attached to the lower portion of the vehicle body with the inclination θ of 30 degrees (usually 5 degrees to 45 degrees) causes ultrasonic vibrations to have a predetermined ultrasonic beam width β, By transmitting to the vicinity of the shoulder T2 of the tire TyL and the road surface as a center and setting it as a reflection point βHV, the outermost high-speed portion of the tire TyL and the road surface become the reflection point of the ultrasonic beam, and the reflected wave The velocity VL parallel to the traveling direction of the vehicle 100.
To get The right-side ultrasonic transducer TRR has the same characteristics as the left-side ultrasonic transducer TRL, and like the former, the tire T
By transmitting to the vicinity of the shoulder portion T2 of yR and the road surface as a reflection point βHV, the outermost high-speed portion of the tire TyR and the road surface are made into the reflection point of the ultrasonic beam, and the reflected wave is It receives waves and obtains a velocity VR parallel to the traveling direction of the vehicle 100.

As shown in FIG. 6 (a), the left ultrasonic transducer T arranged parallel to the traveling direction of the vehicle 100.
The velocity VL is obtained at RL, the left ultrasonic transducer TRL is separated from the left ultrasonic transducer TRL by a predetermined distance N [m] in the width direction of the vehicle 100, and the right ultrasonic transducer TR is parallel to the traveling direction of the vehicle 100.
The velocity VR is obtained from R.

The left ultrasonic wave transmitter / receiver TRL and the right ultrasonic wave transmitter / receiver TRR are molded into respective base members made of synthetic resin as a mounting base and integrated with each other.

Here, the vehicle speed V in the traveling direction as the vehicle speed of the vehicle 100 is V = (VR + VL) / 2 (6) The yaw rate ω of the vehicle 100 is in the traveling direction of the vehicle 100. From the speed difference between the left and right wheels, ω = (VR −VL) / N (7)

Similarly, the distance and the acceleration can be calculated by integrating and differentiating the vehicle speed.

Of course, even if the vehicle speed V is detected by only one left ultrasonic wave transmitter / receiver TRL or right ultrasonic wave transmitter / receiver TRR, one left ultrasonic wave transmitter / receiver is used in straight running and running that is similar thereto. The detection error by the wave transmitter TRL or the right ultrasonic wave transmitter / receiver TRR is so small that it can be ignored.

<Circuit Configuration of Embodiment> FIG. 7 is a circuit configuration diagram in which an ultrasonic wave transmitter / receiver is arranged on the left and right tires as an on-vehicle ultrasonic wave measuring device of an embodiment of the present invention.

In FIG. 7, a microcomputer 1 having an A / D converter inside is a well-known one having a RAM and a ROM and an arithmetic unit necessary for arithmetic control inside. It will be described later. The left ultrasonic transmitter / receiver TRL transmits and receives ultrasonic vibrations in the 200 [KHz] band with a predetermined ultrasonic beam width. Further, the transmission / reception switching circuit 3 performs switching when outputting or receiving waves by ultrasonic vibration from the left ultrasonic wave transmitter / receiver TRL. Further, in the transmission / reception switching circuit 3, the Zener diode ZD1 is turned on at the time of transmission to turn on the left ultrasonic transducer T.
At the same time as transmitting from RL, the receiving circuit is protected by turning on the Zener diode ZD2. During reception, the Zener diodes ZD1 and ZD2 are turned off and the reception state is set.

Zener diode ZD of transmission / reception switching circuit 3
1 is connected in series to the secondary side of the transformer 5, and the primary side of the transformer 5 is connected by a switching transistor 6 so as to supply power. The switching transistor 6 has a rectangular wave of 200 [KH by the output of the frequency dividing circuit 7 to which the external oscillation frequency output of 10 [MHz] is input.
z] is input and the switching transistor 6 is opened and closed intermittently by a signal of 200 [KHz].

Therefore, when the microcomputer 1 sets the intermittent output P1 to "1", the output of the frequency dividing circuit 7 turns the switching transistor 6 on and off, and the secondary side of the transformer 5 has a high voltage of 200 [V]. KHz], which causes the left ultrasonic transducer TRL to generate ultrasonic waves.

The signal from the left ultrasonic wave transmitter / receiver TRL detected via the transmission / reception switching circuit 3 is amplified by the preamplifier 4 and only the reflection of the ultrasonic wave radiated via the bandpass filter 8 is detected. Is further amplified by the amplifier 9 and input to the comparator 10 to be binarized. A part of the input of the comparator 10 is input to the reception level detection circuit 11 and is input to the A / D converter of the microcomputer 1.

The output signal of the comparator 10 is input to the frequency detecting PLL circuit 12, and the number of repetitive pulses proportional to the frequency of the reflected wave reception signal is output as its output signal.

More specifically, since the reception wave can be obtained only intermittently, the reception frequency is detected using the PLL circuit 12 only while the reception gate is open, and while the reception gate is closed. The input voltage of the VCO circuit is held. Further, as another role of the PLL circuit 12, in order to detect the reception frequency with sufficient resolution, frequency multiplication is performed.

Specifically, a pulse obtained by dividing the output by a factor of 8 and the output of the comparator 10 are compared by the phase difference detection circuit PD, and the phase difference is guided to the analog switching circuit AS via the low pass filter LPF. , Its output is input to the resistor R and the capacitor C for sampling and holding, and is also input to the microcomputer 1 via the voltage controlled oscillation circuit VCO. Voltage controlled oscillator VCO
Is output to the phase difference detection circuit PD via the frequency dividing circuit DEM which divides the frequency by 1/8. As a result, the pulse repetition frequency multiplied by 8 is input to the microcomputer 1 from the voltage controlled oscillator circuit VCO.

The outside air temperature is detected by the thermistor 15 and input to the terminal of the A / D converter incorporated in the microcomputer 1.

A left side ultrasonic wave transmitter / receiver TRL and a left side ultrasonic wave transmitter / receiver TRL, a transmission / reception switching circuit 3, a transformer 5, a switching transistor 6, and a frequency dividing circuit 7 are used for transmitting an ultrasonic wave. , Transmission / reception switching circuit 3, preamplifier 4, bandpass filter 8, amplifier 9, comparator 10, reception level detection circuit 11, frequency detection PL
An ultrasonic wave transmitting / receiving circuit 20TR is constituted by the L circuit 12 and a receiving circuit system for receiving ultrasonic waves.

The ultrasonic transmitting / receiving circuit 30TR using the other right ultrasonic transmitting / receiving device TRR has the same circuit configuration. It should be noted that the description of the specific circuit configuration is duplicated, and the description thereof is omitted.

FIG. 8 is a functional configuration diagram of the microcomputer 1 used in the circuit configuration of the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention.

In FIG. 8, a main operation control circuit (MCU) 101 driven by a clock oscillator 105.
Is a PROM 102 storing a program for driving and controlling the microcomputer 1, and a main operation control circuit 1
SRAM 10 for storing data required for 01 arithmetic control
3, a timer / counter 104 having a counting function as a timer and a counter, and 8ch A which is an external analog input
It has an A / D converter 106, a parallel port 107 for external digital input, an interrupt controller 108 for interrupt control, a serial communication interface 109 for serially outputting a vehicle speed calculation result, and the like, which are a data address control bus 110. It is connected by bus.

<Overall Basic Operation of Circuit Configuration> The ultrasonic transmission / reception circuit 20TR operates as follows.

Frequency 2 from the left ultrasonic transmitter / receiver TRL
10 burst waves with 00 [KHz] and 1 [msec] duration
A gate signal for outputting a burst wave is output from the terminal P1 of the parallel port 107 of the microcomputer 1 which is transmitted every [msec]. ON / OFF control of the switching transistor 6 is performed by the output of the frequency dividing circuit 7, and the boosted output of 200 [KHz] is used for the left ultrasonic transducer TR.
Generate ultrasonic waves from L. At this time, the transmission / reception switching circuit 3
Prevents an excessive signal from being applied to the input of the preamplifier 4 on the receiving side during the transmission operation.

When the left ultrasonic transmitter / receiver TRL receives the reflected wave from the road surface, the preamplifier 4 amplifies the wave to about 80 [dB], and then the bandpass filter 8 outputs about 200 dB.
Only a signal of ± 50 [KHz] is taken out, further amplified, then binarized by the comparator 10 and inputted to the frequency detecting PLL circuit 12 to detect the frequency of the reflected wave from the road surface. The output of the comparator 10 is sampled and held by the frequency detection PLL circuit 12 for a time period during which a specific reflected wave from the road surface is detected, and its voltage is held to hold the specific detected frequency of the reflected wave from the road surface. . The output of the voltage controlled oscillator VCO is 8
The frequency is divided by 1 and fed back to be input to the phase difference detection circuit PD, whereby the frequency is locked to a frequency eight times the reflection frequency input to the left ultrasonic transducer TRL. There is. Therefore, if the microcomputer 1 counts the output of the voltage controlled oscillation circuit VCO, the Doppler frequency is detected based on the emitted ultrasonic frequency and the reflected ultrasonic frequency. In this embodiment, a resolution of about 0.5 [Km / h] or higher was obtained in terms of vehicle speed.

Further, the ultrasonic transmitting / receiving circuit 30TR operates in the same manner, but its operation description is omitted.

<Main Control Operation by Microcomputer> FIGS. 9 and 10 are flowcharts of a main program executed by the microcomputer 1 of the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention. FIG. 11 is a flowchart of an interrupt routine executed by the microcomputer 1 of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention, and FIG. 12 is executed by the microcomputer 1 of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention. 7 is a flowchart of a gate position calculation process to be performed.

FIG. 13 is a timing chart of control of the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention. Since the basic operation of the ultrasonic transmitting / receiving circuit 20TR is the same as that of the ultrasonic transmitting / receiving circuit 30TR, the operation of the ultrasonic transmitting / receiving circuit 20TR will be mainly described here, but it goes without saying that the ultrasonic transmitting / receiving circuit 30TR is also controlled in the same manner. To be done.

When a power supply (not shown) is turned on, a reset pulse is input to the main operation control circuit 101 by the action of the power-on reset circuit, and this reset causes PR.
The processing of the main program of FIGS. 9 and 10 stored in the OM 102 is started.

In step S1, the ultrasonic wave transmitting / receiving circuit 20TR
Also, various memories, counters, and timers of the ultrasonic transmission / reception circuit 30TR are cleared or set to predetermined values, and initialization processing for initializing each output port and the like is performed. Particularly, the reception gate start time TG and the sampling start time Ts are set. The reception gate start time TG sets the reception time of the ultrasonic signal corresponding to the mounting height of the vehicle 100 in the standard state as a default value. For example, the mounting height position is H = 280 [mm], the ultrasonic depression angle inclination is φ = 45 degrees, the radiation angle is θ = 30 degrees, and the sound velocity is C = 3.
When it is set to 45 [m / s], TG = 2 × 0.28 / sin45 · sin60 × 1/3
It is set as 45 + 0.3 × 10 ⁻³ = 3.0 [msec]. Here, 0.3 [msec] is added because the position of the reception gate width 0.5 [msec] is set to the center of the reception wave with respect to the transmission pulse width 1 [msec]. is there.

In step S2, the 10 msec sequence end flag F10 for judging the end of the 10 [msec] sequence, the sampling permission flag Fs, and the main timer T are cleared. In step S3, a 100 μsec timer interrupt that interrupts every 100 [μsec] is enabled, and in step S3
In step 4, it is determined whether the 10 msec sequence end flag F10 has come down, and the process waits until the 10 msec sequence end flag F10 comes down, and the subsequent processing is performed every 10 [msec]. 10
When the msec sequence end flag F10 goes down, step S
In step 5, the switching transistor 6 is turned on to open the transmission gates of the ultrasonic transmission / reception circuit 20TR and the ultrasonic transmission / reception circuit 30TR, the main timer T determines whether 1 msec has elapsed in step S6, and the ultrasonic transmission / reception circuit 20T in step S7.
R, the transmission gate of the ultrasonic transmission / reception circuit 30TR is closed.
As a result, a burst signal of ultrasonic waves of 1 [msec] is output. That is, as shown in FIG. 13, in steps S4 to S7, the transmission gate is opened and closed by 1 [ms] every 10 [msec] of the output terminal P1 of the microcomputer 1.
ec] is performed by "1", and during that time, the burst signal shown in the output e1 of the frequency dividing circuit 2 is generated, and the transmission input of the left ultrasonic wave transmitter / receiver TRL and the right ultrasonic wave transmitter / receiver TRR becomes like the output e2. Become. Further, the reflected wave becomes an output e3 via the left ultrasonic transducer TRL or the right ultrasonic transducer TRR.

Up to this point, when ultrasonic waves are transmitted, the ultrasonic wave transmitting / receiving circuit 20TR and the ultrasonic wave transmitting / receiving circuit 30 are used.
TR is controlled simultaneously. However, after that, since the predicted sampling start time Ts for inputting the reflected wave is different for each of the ultrasonic transmission / reception circuit 20TR and the ultrasonic transmission / reception circuit 30TR, the ultrasonic transmission / reception circuit 20TR and the ultrasonic transmission / reception circuit 30TR are individually controlled. However, in order to prevent the description from being complicated, the description of the items common to both is omitted in this embodiment.

In step S8, the ultrasonic wave transmitting / receiving circuit 20TR
The predicted sampling start time Ts for inputting the received signal of the reflected wave to the (ultrasonic wave transmission / reception circuit 30TR) is determined, and when the sampling start time Ts arrives, the sampling permission flag Fs is set in step S9 and the initial setting value is set. Alternatively, the arrival of each reception gate start time TG obtained by the gate position calculation processing routine is awaited in step S10. When each reception gate start time TG arrives, each reception gate of each ultrasonic transmission / reception circuit 20TR (ultrasonic transmission / reception circuit 30TR) is opened in step S11, and the reception gate is turned on for 0.5 [msec] in step S12. After that, the receiving gate is closed in step S13, and
Step 14 is entered. That is, from step S8 to step S
At 13, the arrival of each reception gate start time TG for each ultrasonic transmission / reception circuit 20TR (ultrasonic transmission / reception circuit 30TR) is determined, and reflection is performed corresponding to each ultrasonic transmission / reception circuit 20TR (ultrasonic transmission / reception circuit 30TR). It opens and closes a receiving gate that allows incoming ultrasonic waves to pass through.

Then, in step S14, the gate of the counter COUNT1 (counter COUNT2) incorporated in the main operation control circuit 101 is opened, and in step S15 it is determined whether 3 [msec] has elapsed from the sampling start time Ts. That is, the sampling start time Ts is ± 1.5 [msec] from the center of the ON time of the receiving gate, and each ultrasonic wave is applied to the terminal Aoin (A / D converter terminal A1in) of the A / D converter built in the microcomputer 1. Transceiver circuit 20TR
A signal for each (ultrasonic wave transmission / reception circuit 30TR) is input, and an incoming signal is sampled. When 3 [msec] has elapsed from each sampling start time Ts, step S
At 16, the sampling permission flag Fs is turned off. In step S17, the main timer T determines whether the counter opening time is 2.5 msec from the reception gate start time TG of each ultrasonic transmission / reception circuit 20TR (ultrasonic transmission / reception circuit 30TR), and the counter is counted. The numerical value is read in step S18 and the gate of the counter is closed. In step S19, the outermost high-speed portion of the tire Ty and the road surface are used as the reflection point βHV of the ultrasonic beam.
And the left wheel speed VoL is calculated.

The right wheel speed VoR and the left wheel speed VoL are calculated as VoR = K.countX1 VoL = K.countX2, where countX1 and X2 are coefficient values of the counter K: coefficients determined by the atmospheric temperature.

In step S20, the right side vehicle speed VR is calculated from the right side wheel speed VoR and the left side wheel speed VoL by the equation (5).
And the left side vehicle speed VL are calculated as VR = VoR / (1-k) VL = VoL / (1-k), and the average vehicle speed is obtained by the equation (6).
Also, by integrating and differentiating the velocity vector,
The distance and acceleration can be calculated, and the yaw rate ω of the vehicle 100,
The centrifugal force and the like applied to the vehicle 100 can be calculated.

In step S21, the gate position calculation processing routine is called. Then, in step S22, the sampling time is set 1.2 [msec] ahead of the reception gate start time TG to the sampling start time Ts. That is, the gate position calculation processing routine determines the next reception gate start time TG. And step S
In step S23, the 10 msec sequence end flag F10 is set, the atmospheric temperature is read in step S24, the value of the proportional constant K used for the next vehicle speed calculation is determined in step S25, and the routine after step S4 is repeated and executed.

<Timer Interrupt Operation of Microcomputer> In step S31, the main timer T is incremented by "+1", and in step S32, it is judged by the main timer T whether or not the interrupt timing is every 100 [μsec]. If it is determined that the timing of step S33 and step S34 is 10
The 10 msec sequence end flag F10 for judging the end of the [msec] sequence is cleared and the main timer T is cleared. When it is determined that it is not the timing of the interrupt, the processing of steps S33 and S34 is avoided.

In step S35, it is determined whether or not the sampling permission flag Fs is set. When the sampling permission flag Fs is set, the A / D conversion is started by the output of the reception level detection circuit 11 in step S36.
In step S37, it is written in the buffer, and this routine is exited. If it is determined in step S35 that the sampling permission flag Fs is not set, this routine is exited.

That is, in this routine, the main timer T
The signal level is sampled through the signal level detection circuit 11 every 0.1 [msec], and the signal level is stored in the buffer incorporated in the main operation control circuit 101.

<Gate Position Control Operation by Microcomputer> Reception level data sampled by sampling by interruption every 0.1 [msec] is 15 samples before and after the central sample data, that is, 31 sample data in total. Exists. First, in step S51, an average value X is calculated by a simple average of all level data, and in step S52, the level value of the central sample data is used as the reception level data in the sample center data storage memory X
Store in c. In step S53, it is determined whether or not this is larger than the value obtained by adding a predetermined amount n to the average value X than the level value of 15 samples before and after, and the level value of the central sample data and the level value of 15 samples before and after are the predetermined average value. When the value is larger than the value obtained by adding a predetermined amount n to X, it means the data in which the target reflected wave is regularly reflected, so the process of step S54 is started to adopt this. However, when the level value of the central sample data and the level values of 15 samples before and after are not larger than the value obtained by adding the predetermined amount n to the predetermined average value X, the received waveform is distorted by random interference. Therefore, the adoption of this data is prevented. In step S54, a data period exceeding the value obtained by adding the predetermined amount n to the average value X of all the level data is searched before and after, and the previous time T1 and the subsequent time T are searched.
Ask for 2. In step S55, the width of T2-T1 is 1 [ms
ec], it is determined whether or not the timing for obtaining the reception level data is sufficiently covered. This judgment also prevents the adoption of data in which the received waveform is distorted by random interference. Then, in step S56, (T2 + T1) / 2 is set as the reception gate start time TG. When it is not larger than the value obtained by adding the predetermined amount n to the average value than the central sample level value in step S53, and the width of T2-T1 is 1 [ms in step S55.
ec] and the timing for obtaining the reception level data is not sufficiently covered, this routine is exited.

As described above, the vehicle-mounted ultrasonic measuring device of this embodiment has a predetermined depression angle φ with respect to the left and right tires TyR and TyL.
An ultrasonic wave transmitter / receiver TRR, TR that transmits ultrasonic waves with a gradient of, and uses the outermost high-speed portion of the tires TyR, TyL and the road surface as the reflection point βHV of the ultrasonic beam, and receives the reflected waves.
L and the wheel speed calculating means including step S19 for performing the processing of the equation (5) for calculating the average rotational speed of the left and right tires TyR, TyL from the Doppler frequency of the ultrasonic wave transmitters / receivers TRR, TRL, and the wheel speed. Formula (6) for calculating the vehicle speed V from the rotational speeds of the tires TyR and TyL calculated by the calculating means
And a speed calculation means including step S20 for performing the processing of step S20 and the like. This can be the embodiment of claim 2. In the embodiment of this type, the vehicle speed V is calculated by averaging the rotational speeds of the left and right tires TyR and TyL, so that a highly reliable vehicle speed V can be obtained.

Therefore, the ultrasonic waves are transmitted to the tires TyR, TyL with a predetermined depression angle φ, and the reflected waves are received from the Doppler frequencies of the ultrasonic wave transmitters / receivers TRR, TRL to determine the tires TyR, TyL. The rotation speed and the speed of the road surface are calculated by the speed calculating means in step S19, and the vehicle speed V is calculated from the right wheel speed VoR and the left wheel speed VoL of the tires TyR, TyL calculated in the speed calculating means by the speed calculating means in step S20. Even if the wave front occurs in the forward direction of the tire of the vehicle even on the so-called submerged surface or a relatively soft asphalt road surface where the road surface is wet by rain etc. by calculation, it is affected by the reflection Accurate vehicle speed can be measured without being affected by water droplets.

In this embodiment, the vehicle speed V is obtained from the average rotational speed of the left and right tires TyR and TyL, and the yaw rate is obtained from the rotational speed of the left and right tires TyR and TyL. Acceleration can be calculated. The vehicle speed and the yaw angle are obtained in step S20 of the above embodiment, and the distance and the acceleration can be calculated by integrating and differentiating the speed. Then, by using the obtained speed component, it can be used as a speed detecting device for correcting the moving distance and the moving direction of the navigation system, the vehicle speed and the lateral speed.

By the way, the ultrasonic wave transmitters / receivers TRR, TRL
Is not limited to the present embodiment, and the peripheral portions including the side surfaces of the tires TyR and TyL and the boundary portion with the road surface,
That is, the reflection point αH near the shoulder portion T2 of the tire Ty and the shoulder portion T2 of the sidewall portion T3, and the tire T
Any point where ultrasonic waves can be transmitted, such as a reflection point βHV around the shoulder portion T2 of y and the road surface, and a reflection point γV on the road surface near the contact surface between the lower portion passing through the center line of the tire Ty and the road surface. It may be at any position on the vehicle body. But the tire T
The relationship between yR, TyL and ultrasonic transducers TRR, TRL is
If the ultrasonic wave transmitters / receivers TRR, TRL are arranged in front of the tires TyR, TyL, pebbles or the like caught by the tires TyR, TyL collide with the ultrasonic wave transmitters / receivers TRR, TRL, and water drops, muddy water, etc. Is hard to attach.

In the above embodiment, the left and right tires TyR,
Although the vehicle speed V is obtained from the rotation of TyL, the vehicle speed V can be detected by one of the left and right tires TyR, TyL when the present invention is carried out. This can be the embodiment of claim 1.

That is, an ultrasonic wave transmitter / receiver TR which transmits an ultrasonic wave with a gradient of a predetermined depression angle φ to the tire Ty and receives the reflected wave, and a Doppler of the ultrasonic wave transmitter / receiver TR. Expression (5) for calculating the rotation speed of the tire Ty from the frequency
And the speed calculation means including step S20 for performing the processing of equation (6) for calculating the vehicle speed V from the rotation speed of the tire Ty calculated by the wheel speed calculation means. It is provided with the following, and this can be the embodiment of claim 1.

By the way, in the above embodiment, the vehicle speed is detected by the left ultrasonic wave transmitter / receiver TRL and the right ultrasonic wave transmitter / receiver TRR. Since it is not so fast that it can be ignored, if the ultrasonic beam width is narrowed in an attempt to increase the total gain of the transmitted and received waves, there will be a gap between the beam during transmission and the beam during reception. An ultrasonic wave transmitter / receiver for speed measurement during traveling, or an ultrasonic wave receiver for speed measurement during high speed traveling may be used to receive reflected waves,
Also, the ultrasonic wave transmitting / receiving circuit 20TR and the ultrasonic wave transmitting / receiving circuit 3
Each of the 0TRs may use two ultrasonic transducers, and only one of them may be dedicated to ultrasonic reception. Also,
In particular, the ultrasonic transmission / reception circuit for detecting the speed parallel to the traveling direction of the vehicle is composed of two ultrasonic wave transmitters / receivers and one ultrasonic wave transmitter / receiver, or one ultrasonic wave transmitter / receiver and ultrasonic wave receiver, Reliable speed can be obtained by changing the position where the reflected wave is received according to the vehicle speed.

In the embodiment of the invention described above, the measurement of the vehicle speed V is explained. However, the in-vehicle ultrasonic measuring device of the present invention uses various speed components so that various speeds such as a navigation system and a speed detecting device can be obtained. It can be used for measuring devices and control devices that use information.

[0081]

As described above, in the in-vehicle ultrasonic measuring device according to the invention of claim 1, ultrasonic waves are transmitted to the wheel with a predetermined depression angle inclination, and the ultrasonic wave is transmitted to the vertical center line of the wheel. The rotation speed of the wheel is calculated from the Doppler frequency of the ultrasonic wave transmitter / receiver that receives the reflected wave by using the peripheral part around the intersection of the contact line between the side surface of the tire and the road surface as the reflection point. By calculating the speed from the wheel rotation speed calculated by the wheel speed calculating means, the speed is calculated by the speed calculating means,
Even if the road is flooded or a wave front occurs in the forward direction of the vehicle's tires, it is not affected by the reflection of it and is not affected by water droplets, and accurate vehicle speed is maintained. Can be measured.

Therefore, the vehicle speed can be detected without being affected by the road surface by calculating the wheel rotation speed by the wheel speed calculation means and the wheel speed calculated by the wheel speed calculation means by the speed calculation means. Further, the distance and the acceleration can be calculated by integrating and differentiating the vehicle speed.

In the in-vehicle ultrasonic measuring device of the invention of claim 2, ultrasonic waves are transmitted to the left and right wheels with a predetermined depression angle inclination, and the vertical center line of the wheels, the side surface of the tire, and the road surface. The peripheral point around the point of intersection with the contact line with is used as a reflection point, and the average rotation speed of the left and right wheels is calculated from the Doppler frequency of the ultrasonic transducer that receives the reflected wave, and the wheel speed is calculated. By calculating the speed from the rotational speed of the wheels calculated by the means by the speed calculating means, the wavefront is forward in the traveling direction of the tires of the vehicle, even if the road is a flooded surface or a relatively soft asphalt road surface. Even if the above occurs, the vehicle speed can be accurately measured without being affected by the reflection thereof and being affected by the water droplets. In particular, the left and right wheel speeds that are independent of the left and right wheels can be detected, and a highly reliable vehicle speed can be detected. In particular, the speed in the traveling direction of the vehicle, that is, the vehicle speed or acceleration is detected by the average of the vehicle speeds obtained from the right and left ultrasonic transducers, and the speed difference between the left and right ultrasonic transducers and the distance between them are detected. The yaw rate can be obtained and its trajectory can be traced, which can be used for the measuring device and the control device.

[Brief description of drawings]

FIG. 1 is an explanatory view of a cross section showing the structure of a tire.

FIG. 2 is an explanatory diagram of a basic principle of an in-vehicle ultrasonic measuring device according to an embodiment of the present invention.

FIG. 3 is an explanatory plan view showing a position of an ultrasonic wave transmitter / receiver of a vehicle-mounted ultrasonic wave measuring device according to an embodiment of the present invention and a road surface wave state of wet asphalt.

FIG. 4 is a front explanatory view showing the position of the ultrasonic wave transmitter / receiver of the vehicle-mounted ultrasonic wave measuring device according to the embodiment of the present invention and the state of road surface waves of wet asphalt.

FIG. 5 is an explanatory diagram showing a positional relationship of the ultrasonic transducers in the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram of a basic principle of detecting a vehicle speed, a yaw rate, etc. by using the vehicle-mounted ultrasonic measuring device according to the embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of an in-vehicle ultrasonic measuring device according to an embodiment of the present invention.

FIG. 8 is a functional configuration diagram of a microcomputer used in the circuit configuration of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 9 is a flowchart of a part of a main program executed by the microcomputer of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 10 is a flowchart of another part of the main program executed by the microcomputer of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 11 is a flowchart of an interrupt routine executed by the microcomputer of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 12 is a flowchart of a gate position calculation process executed by the microcomputer of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 13 is a timing chart of control of the vehicle-mounted ultrasonic measurement device according to the embodiment of the present invention.

FIG. 14 is an operation principle diagram in the case where a single ultrasonic wave transmitter / receiver of a vehicle-mounted ultrasonic measuring device transmits and receives a wave.

[Explanation of symbols]

 TR, TRL, TRR Ultrasonic wave transmitter / receiver Ty tire T2 Shoulder part T3 Sidewall part TyR Right tire TyL Left tire 20TR, 30TR Ultrasonic transceiver circuit 100 vehicle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuro Sato 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd.

Claims (2)

[Claims] 1. An ultrasonic wave is transmitted to a wheel with a predetermined depression angle gradient, and a peripheral portion around the intersection of a vertical center line of the wheel and a contact line between a side surface of a tire and a road surface is used as a center. An ultrasonic wave transmitter / receiver that receives the reflected wave as a reflection point, a wheel speed calculation unit that calculates the rotational speed of the wheel from the Doppler frequency of the ultrasonic wave transmitter / receiver, and a wheel speed calculated by the wheel speed calculation unit. A vehicle-mounted ultrasonic measurement device, comprising: a speed calculation unit that calculates a speed from a rotation speed. 2. An ultrasonic wave is transmitted to the left and right wheels with a predetermined depression angle gradient, and its periphery is centered on the intersection of the vertical center line of the wheel and the contact line of the side surface of the tire and the road surface. An ultrasonic wave transmitter / receiver that receives the reflected wave, and a wheel speed calculator that calculates the average rotation speed of the left and right wheels from the Doppler frequency of the ultrasonic transmitter / receiver, and a wheel speed calculator A vehicle-mounted ultrasonic measuring device, comprising: a speed calculating unit that calculates a speed from the rotational speed of the wheel calculated in step 1.