JPH0763849A - Vehicle-borne ultrasonic equipment for measuring vehicle speed - Google Patents

Abstract

PURPOSE:To ensure high reliability of a detected vehicle speed irrespective of the kind of a running road surface by switching vehicle speed detection by an ultrasonic wave over to the vehicle speed detection from wheels by a speed sensor according to the running road surface. CONSTITUTION:An ultrasonic wave is transmitted in a prescribed beam width onto a road surface from ultrasonic transducers TRF and TRR provided at an angle of depression in the direction of advance of a vehicle and a reflected wave therefrom is received. The received reflected wave is amplified 4, passed through BPF 8, and further amplified 9 and then it is binary-coded by a comparator 10 and sample-held by a PLL circuit 12 for frequency detection only for a time for detecting a specific reflected wave from the road surface, whereby a specific detected frequency is held. A microcomputer 1 counts an output of this circuit and detects a Doppler frequency so that a vehicle speed can be obtained from it. When an output of the vehicle speed detection by the ultrasonic wave ceases to be an output of running on the road surface giving a sufficient strength of reflection, such as a dry asphalt road surface, switchover is made to the vehicle speed detection from wheels by a speed sensor whereby the reliability of the vehicle speed detection is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed measuring device mounted on an automobile and using various speed information such as a navigation system, a vehicle speed detecting device, an ABS device, a centrifugal force detecting device, a yaw angle and a yaw rate detecting device. Things
In particular, the present invention relates to a vehicle-mounted ultrasonic vehicle speed 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 is for detecting the 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.

In these techniques, since ultrasonic waves are continuously transmitted and received, it is difficult to identify the reflector and it is difficult to remove noise such as multiple reflected waves.

As another velocity 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 when the ultrasonic waves are reflected and received from a road surface which is a specific reflective object, and a predetermined wavelength of the received wave. The Doppler shift amount is obtained by measuring the minutes, and the vehicle speed is measured.

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

According to this technique, ultrasonic waves are radiated from a wave transmitter / receiver on a road surface in the front or front direction of a vehicle at a predetermined depression angle, and from the received signal of the radiated ultrasonic waves and the reflected wave of the projection on the road surface 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 to detect the presence and size of the road surface projection in front of the vehicle. Then, the vehicle height is detected from the straight line distance and the emission angle of the ultrasonic wave when the reflected wave returns from the road surface, and the vehicle speed is detected based on the obtained Doppler frequency.

Particularly, in the technique disclosed in the above publication, ultrasonic waves are radiated at the same 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. The vehicle height is detected by measuring the time until the reflected wave is received.

In this way, the ultrasonic waves are used to detect the protrusions and the like on the front road surface when the vehicle is running, and also to detect the vehicle height, the vehicle speed, and the like.

[0010]

An ultrasonic vehicle speed measuring device for a vehicle, which transmits an ultrasonic wave of this kind to a road surface and receives a reflected wave from the road surface, is a wheel vehicle speed for detecting a vehicle speed from a wheel speed. Compared with the detection means, the vehicle speed can be detected without being affected by the air pressure and load of the wheels, tire size, slip, and the like. However, on an asphalt road surface where water or the like has adhered to the submerged road surface or the surface, the detection level of the reflected wave from the road surface may decrease, the detection level may fluctuate, and the reflected wave due to water splash may occur. Cause error,
The vehicle speed detection accuracy decreases, and the reliability of the vehicle speed value decreases.

Therefore, an object of the present invention is to provide an on-vehicle ultrasonic vehicle speed measuring device which can increase the reliability of the detected vehicle speed without being affected by the type of road surface on which the vehicle travels.

[0012]

A vehicle-mounted ultrasonic vehicle speed measuring device according to claim 1 is mounted on a vehicle, transmits an ultrasonic signal to a target, and receives the reflected wave to determine the vehicle speed. Ultrasonic vehicle speed detecting means for detecting, and wheel vehicle speed detecting means for detecting the vehicle speed from the vehicle wheel speed of the vehicle, the output of the ultrasonic vehicle speed detecting means of the road surface traveling in a state having a sufficient reflection strength When the output is stopped, the vehicle speed output of the vehicle is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means.

An on-vehicle ultrasonic vehicle speed measuring device according to a second aspect of the present invention is mounted on a vehicle, transmits ultrasonic signals to a target, and receives the reflected waves to detect the vehicle speed. Means, a vehicle speed detecting means for detecting a vehicle speed from the vehicle speed of the vehicle, and an ultrasonic vehicle speed detecting means for traveling on a road surface in a state where the output of the ultrasonic vehicle speed detecting means has a sufficient reflection intensity. When the output of the ultrasonic vehicle speed detection means is no longer the output of road running in a state having sufficient reflection strength, the learning means for learning the output relationship with the output of the wheel vehicle speed detection means from the output, The vehicle speed output of the vehicle is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means, and the output of the wheel vehicle speed detecting means is corrected using the result obtained by the learning means to output the vehicle speed. Tosu It is intended.

[0014]

According to the present invention, an ultrasonic vehicle speed detecting means mounted on a vehicle for transmitting an ultrasonic signal to a target object and receiving the reflected wave to detect the vehicle speed, and a wheel speed of the vehicle. When the output of the ultrasonic vehicle speed detecting means is no longer the road surface output in a state having sufficient reflection strength, the vehicle speed output of the vehicle is changed by the switching means. The output of the ultrasonic vehicle speed detecting means is switched to the output of the wheel vehicle speed detecting means, and the type of the vehicle speed detecting means is switched to the one with less error depending on the road surface on which the vehicle travels.

According to a second aspect of the present invention, it is attached to a vehicle,
It is provided with an ultrasonic vehicle speed detecting means for transmitting an ultrasonic signal to a target object and receiving the reflected wave to detect the vehicle speed, and a wheel vehicle speed detecting means for detecting the vehicle speed from the wheel speed of the vehicle. When the output of the ultrasonic vehicle speed detecting means is no longer the road surface output in a state of having a sufficient reflection intensity, the vehicle speed output of the vehicle is changed from the output of the ultrasonic vehicle speed detecting means to the wheel vehicle speed detecting means by the switching means. Output, the type of the vehicle speed detection means is switched to one with less error depending on the road surface on which the vehicle travels, and when the road surface travels in a state where the output of the ultrasonic vehicle speed detection means has a sufficient reflection intensity, the ultrasonic wave By using the result obtained by the learning means for learning the output relationship between the output of the vehicle speed detecting means and the output of the wheel vehicle speed detecting means, the output of the wheel vehicle speed detecting means is corrected and used as the vehicle speed output. It is intended.

[0016]

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

<Description of Basic Operation> FIG. 1 is an explanatory view of the basic operation of an in-vehicle ultrasonic vehicle speed measuring device according to an embodiment of the present invention.
(A) is a side view of the vehicle-mounted ultrasonic vehicle speed measuring device by the pair beam method, and (b) is a basic operation explanatory view of the vehicle-mounted ultrasonic vehicle speed measuring device by the pair beam method.

In FIG. 1, an ultrasonic transducer TRF, which is parallel to the traveling direction of the vehicle 100 and whose depression angle is set to 45 degrees with respect to the traveling direction, is designed to generate ultrasonic vibrations in the 200 [KHz] band at a predetermined ultrasonic wave. The beam width is transmitted to the road surface and the reflected wave is received, and the vehicle speed (speed vector) VF parallel to the traveling direction of the vehicle 100 is obtained. Specifically, the ultrasonic wave transmitter / receiver TRF is disposed in the front center of the vehicle 100. The ultrasonic wave transmitter / receiver TRR has the same characteristics as the ultrasonic wave transmitter / receiver TRF, transmits ultrasonic waves to the road surface with a predetermined ultrasonic beam width, and receives the reflected waves thereof. As shown in b), the ultrasonic wave transmitter / receiver TRF, which is arranged in parallel to the traveling direction of the vehicle 100, is disposed at a position angularly displaced by 180 degrees, and the depression angle is set to 45 degrees with respect to the road surface. It is set and the vehicle speed (speed vector) VR is obtained.

The ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR are housed and integrated in a housing B together with a printed circuit board and the like. And FIG. 1 (b)
As shown in, the housing B is attached to the lower surface of the vehicle 100. In addition, the ultrasonic transmitter / receiver TR of this embodiment
The height of radiating the ultrasonic wave of R is H [m].

The vehicle speed VF in the traveling direction of the vehicle 100 is VF = V + ΔV (1) The vehicle speed VR in the anti-traveling direction of the vehicle 100 is VR = V−ΔV (2) V is an erroneous vehicle speed component due to bouncing, pitching and the like. Therefore, the vehicle speed PV measured by the pair beam method is PV = (VF + VR) / 2 = V (3).

Similarly, the distance and the acceleration can be calculated by integrating and differentiating the vehicle speed vector. At this time, the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR vibrate vertically when the vehicle is running. , Nose up, nose down, and vehicle height changes due to cornering change the time until the reflected wave arrives. Therefore, by adjusting the timing of opening the reception gate for each ultrasonic transducer TRF, ultrasonic transducer TRR,
It accurately captures the target reflected wave, calculates the Doppler frequency, and obtains the accurate vehicle speed.

<Circuit Configuration of the Embodiment> FIG. 2 is a circuit configuration diagram of an in-vehicle ultrasonic vehicle speed measuring device according to an embodiment of the present invention.

In FIG. 2, a microcomputer 1 having an A / D converter of 8ch inside is a known one having a RAM and a ROM and an arithmetic unit necessary for arithmetic control, and its internal function. The description will be given later. The ultrasonic wave transmitter / receiver TRF transmits / receives ultrasonic vibration in the 200 [KHz] band with a predetermined ultrasonic beam width.
Further, the transmission / reception switching circuit 3 performs switching when outputting or receiving an ultrasonic wave from the ultrasonic wave transmitter / receiver TRF. That is, in the transmission / reception switching circuit 3, the bidirectional diodes ZD1 and ZD2 are turned on during transmission, and the ultrasonic transducer TRF
The signal is output from the device and protects the receiving circuit, while the bidirectional diodes ZD1 and ZD2 are received during reception.
Is turned off, and the reception signal is output to the preamplifier 4.

Bidirectional diode ZD1 of the transmission / reception switching circuit 3
Are 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 outputs 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 ultrasonic transducer TRF to generate ultrasonic waves.

The signal from the ultrasonic wave transmitter / receiver TRF detected through the transmission / reception switching circuit 3 is amplified by the preamplifier 4 and is output within ± 50 [KHz] of the ultrasonic wave frequency corresponding to the speed change such as the vehicle speed. Only the reflection of the ultrasonic wave radiated through the band pass filter 8 that passes the signal is detected, 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 a reception level detection circuit 11 composed of a diode D11 and a capacitor C11, envelope-detected there, and then input to an A / D converter incorporated in 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 output of the comparator 10 is output as its output signal.

More specifically, the output of the comparator 10 is ± 50 of the ultrasonic frequency to be output corresponding to the speed change such as the vehicle speed.
Since the frequency is about [KHz], the frequency is multiplied to obtain the necessary resolution. Since the output of the comparator 10 has meaning only during the time when the receiving gate is open, the voltage proportional to the frequency is sampled and held by the time signal during that time. If the receiving gate is closed and not valid, P
The function as the LL circuit is stopped and the sampled and held voltage is held.

Specifically, a pulse obtained by dividing the output of the voltage controlled oscillation circuit VCO by 1/8 and the output of the comparator 10 are compared by the phase difference detection circuit PD, and the phase difference is passed through the low pass filter LPF. It is led to the analog switching circuit AS, and its output is input to the resistance R and the capacitor C for sampling and holding, and also input to the microcomputer 1 via the voltage controlled oscillator circuit VCO. The output of the voltage controlled oscillation circuit VCO is input 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 A2in of the A / D converter incorporated in the microcomputer 1.

The pulse input of the known speed sensor is pulse-shaped by the waveform shaping circuit 16 and input to the interrupt terminal INT.

An ultrasonic wave transmitter / receiver TRF of this kind, a transmission / reception switching circuit 3, a transformer 5, a switching transistor 6 and a frequency dividing circuit 7, and a transmission circuit system for transmitting an ultrasonic wave, and an ultrasonic wave transmitter / receiver TRF, The ultrasonic transmission / reception circuit FORE includes a switching circuit 3, a preamplifier 4, a bandpass filter 8, an amplifier 9, a comparator 10, a reception level detection circuit 11, and a frequency detection PLL circuit 12, and a reception circuit system that receives ultrasonic waves. Are configured.

The ultrasonic transmission / reception circuit REAR using another ultrasonic wave transmitter / receiver TRR has the same circuit configuration. Note that the description of the specific circuit configuration is duplicated, and therefore the description thereof is omitted here.

FIG. 3 shows a microcomputer 1 used in the circuit configuration of the vehicle-mounted ultrasonic vehicle speed measuring apparatus according to the embodiment of the present invention.
3 is a functional configuration diagram of FIG.

In FIG. 3, 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 a D / D converter 106, a parallel port 107 for external digital input / output, 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. It is bus-coupled at 110.

<Overall Basic Operation of Circuit Configuration> The ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR operate as follows. Since the basic operation of the ultrasonic transmission / reception circuit FORE is the same as that of the ultrasonic transmission / reception circuit REAR, the description will focus on the ultrasonic transmission / reception circuit FORE here, but naturally the ultrasonic transmission / reception circuit REAR is also independent. Controlled.

Ultrasonic wave transceiver TRF, ultrasonic wave transceiver T
From RR, frequency 200 [KHz], duration 1 [msec]
A gate signal for intermittent output is output from the terminal P1 of the parallel port 107 of the microcomputer 1 which transmits intermittent ultrasonic waves every 10 [msec]. The switching transistor 6 is on / off controlled by the output of the frequency dividing circuit 7, and ultrasonic waves are generated from the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR by the boosted output of 200 [KHz]. 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.

At this time, the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR may be output simultaneously or in a time-division manner. In the case of this embodiment, since the directions are opposite to each other, the signals are simultaneously output from the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR.

When the ultrasonic wave transmitter / receiver TRF (ultrasonic wave transmitter / receiver TRR) receives the reflected wave from the road surface, it is amplified by the preamplifier 4 with a gain of about 80 [dB], and then the bandpass filter 8 is used. Only the signal of about 200 ± 50 [KHz] is taken out, and after amplifying it, the comparator 1
It is binarized by 0 and input to the frequency detection 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 circuit VCO is divided into ⅛ and fed back to be input to the phase difference detection circuit PD, which is then input to the ultrasonic wave transmitter / receiver TRF (ultrasonic wave transmitter / receiver TRR). It is designed to be locked at a frequency that is eight times the reflection frequency. Therefore, if the microcomputer 1 counts the output of the voltage controlled oscillation circuit VCO, the Doppler frequency can be detected based on the radiated ultrasonic frequency and the reflected ultrasonic frequency. In this embodiment, a resolution of about 0.5 [Km / h] or more can be obtained in terms of vehicle speed.

Further, the ultrasonic transmitting / receiving circuit REAR operates in a similar manner, but the explanation of the operation is duplicated and therefore omitted.

4 and 5 are flowcharts of the main program executed by the microcomputer 1 of the vehicle-mounted ultrasonic vehicle speed measuring apparatus according to the embodiment of the present invention. In addition, FIG.
Is a flowchart of the timer interrupt processing routine,
7 is a flowchart of a wheel pulse interrupt processing routine, FIG. 8 is a flowchart of a wheel speed calculation processing routine, FIG. 9 is a flowchart of a vehicle speed calculation processing routine, FIG. 10 is a flowchart of a beam mode determination processing routine, and FIG. 12 is a flowchart of a vehicle speed selection processing routine, FIG. 12 is a flowchart of a traveling distance measurement processing routine, FIG. 13 is a flowchart of a vehicle speed coefficient correction processing routine, and FIG. 14 is a flowchart of a gate position calculation processing routine. Further, FIG. 15 is a timing chart of control of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

<Main Control Operation by Microcomputer (Refer to FIGS. 4 and 5)> The basic operation is the same as that of the ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR. Although the operation will be described below, the ultrasonic transmission / reception circuit REAR is naturally controlled in the same manner.

First, when the power source (not shown) is turned on, the main operation control circuit 1 is operated by the function of the power-on reset circuit.
A reset pulse is input to 01, and this reset starts the processing of the main program stored in the PROM 102 shown in FIGS.

In step S1, the ultrasonic wave transmitting / receiving circuit FOR is
E, various memories and counters and timers used in the ultrasonic transmission / reception circuit REAR are cleared or set to predetermined values,
Performs initialization processing to initialize each output port, etc. Particularly, the reception gate start time TG and the sampling start time Ts are set. This receiving gate start time TG is the vehicle 100 in the standard state as a default value.
Set the reception time of the ultrasonic signal corresponding to the mounting height of. For example, when the mounting height position is H = 280 [mm], the ultrasonic depression angle is φ = 45 degrees, the radiation angle is θ = 30 degrees, and the sound velocity is C = 345 [m / s], TG = 2 × It is set as 0.28 / sin45 · sin60 × 1/345 + 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
At step 5, a wheel speed calculation processing routine as a wheel vehicle speed detecting means including a known speed sensor for detecting the vehicle speed from the wheel speed of the vehicle 100 is called. In step S6, the switching transistor 6 is turned on to open the transmission gates of the ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR, the main timer T determines in step S7 whether 1 msec has elapsed, and in step S8, the ultrasonic transmission / reception circuit FORE, The transmission gate of the sound wave transmission / reception circuit REAR is closed. As a result, a burst signal of ultrasonic waves of 1 [msec] is output. That is, as shown in FIG. 15, in steps S5 to S8, the transmission gate is opened and closed by "1" for 1 [msec] every 10 [msec] of the output terminal P1 of the microcomputer 1, and the frequency division is performed during that period. Output e1 of circuit 2
The burst signal shown in FIG. 2 is obtained, and the transmission input of the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR becomes the output e2. Further, the reflected wave becomes an output e3 via the ultrasonic wave transmitter / receiver TRF or the ultrasonic wave transmitter / receiver TRR.

Up to this point, when transmitting an ultrasonic wave, the ultrasonic wave transmitting / receiving circuit FORE, the ultrasonic wave transmitting / receiving circuit RE
AR is controlled at the same time. 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 FORE and the ultrasonic transmission / reception circuit REAR, the ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR 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 S9, the ultrasonic wave transmitting / receiving circuit FORE
The predicted sampling start time Ts for inputting the received signal of the reflected wave to the (ultrasonic wave transmission / reception circuit REAR) is determined, and when the sampling start time Ts arrives, the sampling permission flag Fs is set in step S10 and the initial setting value is set. Alternatively, the arrival of each reception gate start time TG obtained in the gate position calculation processing routine is awaited in step S11. When each reception gate start time TG arrives,
In step S12, each reception gate of each ultrasonic transmission / reception circuit FORE (ultrasonic transmission / reception circuit REAR) is opened, in step S13 the reception gate is turned on for 0.5 [msec], and then in step S14, the reception gate is closed. Step S1
Step 5 starts. That is, from step S9 to step S1
At 4, the arrival of each reception gate start time TG for each ultrasonic transmission / reception circuit FORE (ultrasonic transmission / reception circuit REAR) is judged, and the reflection is performed corresponding to each ultrasonic transmission / reception circuit FORE (ultrasonic transmission / reception circuit REAR). It opens and closes a receiving gate that allows incoming ultrasonic waves to pass through.

Then, in step S15, the gate of the counter COUNT1 (counter COUNT2) incorporated in the main operation control circuit 101 is opened, and in step S16, 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. Transmitter / receiver circuit FORE
A signal for each (ultrasonic wave transmission / reception circuit REAR) is input and the incoming signal is sampled. When 3 [msec] has elapsed from each sampling start time Ts, step S
At 17, the sampling permission flag Fs is turned off. In step S18, 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 FORE (ultrasonic transmission / reception circuit REAR), and the counter is counted. The numerical value is read in step S19, the gate of the counter is closed, and the count value of the counter is read. In step S20, the vehicle speed V in the traveling direction of the vehicle 100 in which the road surface is the reflection point of the ultrasonic beam
F, a "vehicle speed calculation process" routine is called to calculate the vehicle speed VR in the reverse traveling direction. Further, the distance and the acceleration can be calculated by integrating and differentiating the velocity vector.

"Gate position calculation processing" in step S21
Call the routine. Then, in step S22, the reception gate start time T is added to the sampling start time Ts.
Set the sampling time 1.2 [msec] ahead of G. That is, the gate position calculation processing routine determines the next reception gate start time TG. Then, the 10 msec sequence end flag F10 is set in step S23, the atmospheric temperature is read in step S24, and the value of the coefficient K determined by the atmospheric temperature used for the next vehicle speed calculation is determined.
The routine after step S4 is repeated and executed.

<Timer Interrupt Processing (See FIG. 6)> In step S31, the main timer T is incremented by +1. In step S32, the main timer T determines whether or not the interrupt timing is every 10 [msec].
When it is judged that it is the timing of the interruption in step S33 and step S34, the end of the sequence of 10 [msec] is judged.
To clear the main timer T. 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 unit 101.

<Wheel Pulse Interrupt Processing (See FIG. 7)> The output from a known speed sensor as a wheel vehicle speed detecting means for detecting the vehicle speed from the wheel speed of the vehicle 100 is input to the interrupt terminal INT of the main arithmetic unit 101. And step S4
At 1 the input port determines whether or not the signal is noise, and when it is not noise, the value of the vehicle speed conversion count Nd for each interrupt is given to the interrupt counter Np that counts the number of interrupts at step S42. (Initial value = 363) is added to the value of the interrupt counter Np, and this routine is exited.

That is, in this routine, the output from the speed sensor is stored in the interrupt counting counter Np. In addition,
The value of the vehicle speed conversion coefficient Nd (initial value = 363) is determined in relation to the vehicle speed conversion coefficient 1/256 used later, and is not limited to this value.

<Wheel speed calculation processing (see FIG. 8)> When this "wheel speed calculation processing" routine is called in step S5 of FIG. 4, the calculation is performed once per second in step S51. To counter Tw to measure timing +
This routine is incremented by 1, and it is determined in step S52 whether or not the counter Tw is 100, and this routine is exited without executing the following processing until the counter Tw reaches 100. When the counter Tw reaches 100, the counter Tw is canceled in step S53, and the conversion coefficient 1/25 for converting the value of the interrupt counting counter Np into the vehicle speed in step S54.
Multiply 6 by the value of the interrupt counter Np and multiply it by the vehicle speed V
w [km / h]. Then, in step S55, the interrupt counting counter Np is canceled, and this routine is exited.

That is, in this routine, the value of the interrupt counting counter Np, which stores the output from the speed sensor, is used to convert the value of the interrupt counting counter Np into the vehicle speed Vw.

<Vehicle speed calculation processing (see FIG. 9)> When the "vehicle speed calculation processing" routine is called in step S20 of FIG. 5, the vehicle speed VF of the vehicle 100 in the forward direction, that is, the traveling direction, is determined in steps S61 and S62. And REAR
The vehicle speed VR in the opposite direction is as follows: VF = K.countXF VR = K.countXR where countXF, XR: Count value of counter K: Calculation of each vehicle speed by a coefficient determined by atmospheric temperature. Then, step S6
In step 3, the measured vehicle speed error depending on the vehicle speed is corrected, and step S
In 64, call the “beam mode determination process” routine,
The "vehicle speed selection process" routine is called in step S65, and the "mileage measurement process" routine is called in step S66, and this routine is exited.

That is, in this routine, the vehicle speed VF in the traveling direction (FORE side) and the vehicle speed VR in the opposite traveling direction VR (REAR)
Side) calculates each vehicle speed obtained in.

<Beam Mode Determination Processing (See FIG. 10)>
When the "beam mode determination processing" routine is called in step S64 of the "vehicle speed calculation processing" routine of FIG.
The reception level Ev on the REAR side is stored in the memory Ar in step S71, and the reception level Ev on the FORE side is stored in the memory Af in step S72. In step S73, the reception level Ev on the REAR side stored in the memory Ar and the reception level Ev on the FORE side stored in the memory Af are added,
A value obtained by subtracting the memory Ar from the memory Af in step S74 is determined in order to determine whether the sum is greater than a predetermined threshold Ao, and when the sum is greater than the predetermined threshold Ao, the reception level Ev is biased. Is greater than a predetermined threshold Ao, and it is determined in step S75 whether the value obtained by subtracting the memory Af from the memory Ar is larger than the predetermined threshold Ao.

When the value obtained by subtracting the memory Ar from the memory Af is larger than the predetermined threshold value Ao, it is determined in step S79 whether the mode determination internal flag Fm is "1", and the mode determination internal flag Fm is not "1". When step S80
The mode determination internal flag Fm is set to "1". When the value obtained by subtracting the memory Af from the memory Ar is larger than the predetermined threshold value Ao, it is determined in step S81 whether the mode determination internal flag Fm is "2", and the mode determination internal flag Fm is not "2". In step S82, the mode determination internal flag Fm is set to "2", and when the mode determination internal flag Fm is "2", the continuation number counter Ne for counting the continuation number is incremented by 1 in step S83.

Further, in step S74, the value obtained by subtracting the memory Ar from the memory Af is not larger than the predetermined threshold Ao,
When it is determined in step S75 that the value obtained by subtracting the memory Af from the memory Ar is not larger than the predetermined threshold value Ao, it is determined in step S76 whether the mode determination internal flag Fm is "0", and the mode determination internal flag Fm is " If it is not "0", the mode determination internal flag Fm is cleared in step S77, the continuation number counter Ne for counting the continuation number is cleared in step S78, and this routine is exited.

When it is determined in step S76 that the mode determination internal flag Fm is "0", and when it is determined in step S79 that the mode determination internal flag Fm is "1", the number of continuations is determined in step S83. The continuation number counter Ne to be counted is incremented by +1 and the continuation number counter Ne is set to a predetermined continuation number threshold N in step S84.
It judges whether or not it exceeds o, and continues count counter Ne
Is greater than the predetermined threshold value No of continuation times, the value of the mode determination internal flag Fm is stored in the mode designation memory BMOD storing the beam mode designation variable code in step S85.

Then, in step S73, the reception level Ev on the REAR side stored in the memory Ar and the reception level Ev on the FORE side stored in the memory Af are added, and it is determined whether the sum is larger than a predetermined threshold value Ao. When it is not larger than the predetermined threshold value Ao, it is determined in step S86 whether the mode determination internal flag Fm is "3", and the mode determination internal flag Fm is determined.
When m is not "3", the mode determination internal flag Fm is set to "3" in step S87, the continuation number counter Ne for counting the continuation number is cleared in step S78, and this routine is exited.

That is, in this routine, it is determined whether the reception level Ev on the FORE side stored in the memory Af and the reception level Ev on the REAR side stored in the memory Ar are equal to or more than a predetermined value, and waits for the predetermined reception level. The mode designation memory BMOD is used so that the vehicle speed obtained by the received wave is used.
The value of the mode determination internal flag Fm corresponding to the state is stored in.

<Vehicle speed selection processing (see FIG. 11)> In step S65 of the "vehicle speed calculation processing" routine shown in FIG.
When the "vehicle speed selection process" routine is called, the value of the mode determination internal flag Fm of the mode designation memory BMOD storing the beam mode designation variable code is determined in step S90, and the mode determination internal flag Fm of the mode designation memory BMOD is determined. When the value is "0", the vehicle speed V is determined in step S91.
Is a simple average of the vehicle speed VF on the FORE side and the vehicle speed VR on the REAR side. Further, when the value of the mode determination internal flag Fm of the mode designation memory BMOD is "1", it means that the output on the ultrasonic transducer TRF side is large, and therefore the vehicle speed V is changed to the vehicle speed VF on the FORE side in step S92. And
Then, when the value of the mode determination internal flag Fm of the mode designation memory BMOD is "2", it means that the output on the ultrasonic transducer TRR side is large, so that the step S9 is performed.
At 3, the vehicle speed V is set to the vehicle speed VR on the REAR side. Furthermore, when the value of the mode determination internal flag Fm of the mode designation memory BMOD is "3", the output level of the ultrasonic transducer TRR side and the output level of the ultrasonic transducer TRF side are low, and they cannot be used. In step S94, the vehicle speed V is set to the vehicle speed Vw obtained from a known speed sensor.

That is, in this routine, it is determined whether the reception level Ev on the FORE side stored in the memory Af of the "beam mode determination processing" routine and the reception level Ev on the REAR side stored in the memory Ar are equal to or more than a predetermined value. As a result, when the reception level Ev is low, the vehicle speed V is determined according to the contents of the mode designation memory BMOD so as to select the side of the reception level Ev with high reliability. When the output on the ultrasonic wave transmitter / receiver TR R side and the output on the ultrasonic wave transmitter / receiver TR F side cannot be used, the vehicle speed V is set to the vehicle speed Vw obtained from a known speed sensor.

<Running Distance Measuring Process (See FIG. 12)> This routine is executed at step S10 when the "running distance measuring process" routine is called at step S66 shown in FIG.
In 1, it is judged whether the content of the mode designation memory BMOD is "0", and the vehicle speed V is functioning by the pair beam method in which the vehicle speed VF on the FORE side and the vehicle speed VR on the REAR side are simply averaged.
When the pair beam method does not work, the ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR of the ultrasonic vehicle speed detection means are not functioning accurately. The flag FBMOB to be recorded is cleared (= 0), and this routine is exited.

In step S101, the mode designation memory BM
When OD is "0" and the flag FBMOB is not set in step S103 (= 0), that is, the ultrasonic wave transmitting / receiving circuit FORE and the ultrasonic wave transmitting / receiving circuit REA of the ultrasonic vehicle speed detecting means.
Since R means that it has started to function correctly, the memory LSPS and the memory LSS are cleared in step S104, the flag FBMOB is set, and this routine is exited.

When the flag FBMOB is set (= 1) in step S103, it means that the ultrasonic wave transmitting / receiving circuit FORE and the ultrasonic wave transmitting / receiving circuit REAR of the ultrasonic wave vehicle speed detecting means are functioning accurately and continuously. , Step S1
In the memory LSPS storing the distance corresponding to the wheel vehicle speed detecting means 05, the product Vw · Δt of the vehicle speed Vw and a predetermined unit short time Δt (1 second in this embodiment), that is, the unit short time Δt A memory LSS for adding the traveling distance and storing the distance corresponding to the ultrasonic vehicle speed detecting means in step S106.
Then, the product V · Δt of the vehicle speed V and the predetermined unit short time Δt, that is, the traveling distance for the unit short time Δt is added. Then, the traveling distance for the unit short time Δt stored in the memory LSS in step S107 is, for example, 2 in this embodiment.
Judge whether [km] is exceeded, and if not, exit this routine. When it is determined that the traveling distance for the unit short time Δt stored in the memory LSS exceeds, for example, 2 [km], the "vehicle speed coefficient correction process" routine is called to correct the vehicle speed coefficient in step S108, and step S109 Then lower the flag FBMOB.

That is, in this routine, the vehicle speed Vw obtained by the wheel vehicle speed detecting means and the vehicle speed V obtained by the ultrasonic vehicle speed detecting means are multiplied by a predetermined unit short time Δt to replace the distance, and the distance is integrated. Each time a predetermined distance (2 [km]) is exceeded, a "vehicle speed coefficient correction process" routine is called, and the vehicle speed Vw obtained by the wheel vehicle speed detection means is calculated based on the vehicle speed V obtained by the ultrasonic vehicle speed detection means. In order to make the correction, the vehicle speed coefficient correction to be described later is learned.

<Vehicle speed coefficient correction processing (see FIG. 13)> When this "wheel coefficient correction processing" routine is called in step S108, the traveling distance for the unit short time Δt stored in the memory LSPS in step S111 is determined. Using the difference between the added distance and the added running distance for the unit short time Δt stored in the memory LSS, {(LSPS
In the present embodiment in which the error rate Err is calculated by −LSS) / LSPS} × 100 and the error rate Err is set as the threshold value in step S112 and step S113, for example, exceeds 0.2% or, for example, −0. If the error rate Err exceeds 0.2%, it is determined in step S11.
Nd (initial value = 363) is subtracted by “−1” at 4, and
When the error rate Err is below -0.2%, "+1" is added to Nd in step S115, and this routine is exited.

That is, in this routine, the error rate Err is ±
When it exceeds 0.2%, the value of the vehicle speed conversion count Nd (initial value = 363) is added by ± 1, and the vehicle speed V obtained by the ultrasonic vehicle speed detecting means is made an accurate vehicle speed. The obtained vehicle speed Vw is constantly corrected and corrected.

<Gate Position Detection Processing (See FIG. 14)>
The reception level data sampled by sampling by interruption every 0.1 [msec] has 15 samples before and after the central sample data, that is, 31 sample data in total. First, in step S121, the average value X is calculated by a simple average of all level data, and in step S122, the level value of the central sample data is stored in the sample central data storage memory Xc as the reception level data. In step S123, it is determined whether or not this is larger than the value obtained by adding the 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 it is larger than the value obtained by adding a predetermined amount n to X, it means data in which the target reflected wave is regularly reflected, and therefore the process of step S124 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 S124, a data period exceeding a value obtained by adding a 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 S125, the width of T2-T1 is 1
In [msec], 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. And step S1
Receive (T2 + T1) / 2 at 26 Gate start time T
Set as G. When the average sample value is not larger than the value obtained by adding the predetermined amount n to the average sample level value in step S123, and the width of T2-T1 is not 1 [msec] or more in step S125, the reception level data is obtained. This routine is exited when the timing is not covered sufficiently.

As described above, the vehicle-mounted ultrasonic vehicle speed measuring apparatus according to the present embodiment transmits the ultrasonic signal to the target and receives the reflected wave to detect the vehicle speed. The vehicle speed detecting means is attached to the vehicle 100 and outputs from the ultrasonic wave transmitter / receiver TRF and the ultrasonic wave transmitter / receiver TRR.
As in 2, the ultrasonic signal is intermittently transmitted to the road surface, the reflected wave is received as a signal e3, the received signal e3 is amplified, and the amplified signal is sampled and held by a resistor R and The signal input to the capacitor C, sampled and held, is voltage / frequency converted by the voltage controlled oscillation circuit VCO, and a frequency proportional to the reflected wave is generated by the microcomputer 1.
Enter to get the vehicle speed. Further, the wheel vehicle speed detecting means including step S5 detects the wheel speed of the vehicle 100, that is, the vehicle speed from a known speed sensor. And
When the output of the ultrasonic vehicle speed detecting means is no longer an output of a normal ideal road surface having a dry surface, that is, a so-called dry asphalt road surface having a sufficient reflection strength, the vehicle speed output of the vehicle 100 is The present invention is provided with a switching means including steps S71 to S85 and steps S90 to S94 for switching from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means, which is an embodiment of claim 1. be able to.

Therefore, in the present embodiment, when the output of the ultrasonic vehicle speed detecting means is no longer the output of the road surface traveling with a sufficient reflection strength such as dry asphalt road surface under the normal traveling state, that is, the pair beam type memory Af. Received level Ev on the FORE side stored in R and R stored in the memory Ar
If the reception level Ev on the EAR side is greater than or equal to a predetermined value, and if the sum of both reception levels Ev is small, it is reflected from the road surface by running on the submerged road surface and on an asphalt road surface with water adhered to the surface. It is determined that the detection level of the waves is low, and the cause of the error is the decrease in the reflectance of the submerged road surface, the generation of reflected waves due to water splashes, and the decrease in the reflectance of the asphalt road surface with water on the surface. In order to prevent this, it is possible to improve the reliability of vehicle speed detection by switching from the normal traveling ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means.

Of course, even if there is a possibility that the height of the vehicle body may fluctuate due to vertical vibrations, nose up, nose down, or cornering due to unevenness of the road surface, the side of the receiving level Ev with high reliability is selected. Therefore, since the vehicle speed V is determined according to the contents of the mode designation memory BMOD, it is possible to improve the reliability of the vehicle speed detection by the ultrasonic vehicle speed detection means in normal traveling.

The above embodiment is mounted on the vehicle 100,
The ultrasonic vehicle speed detecting means comprises a step S20 of transmitting an ultrasonic signal to a target object and receiving a reflected wave thereof to detect a vehicle speed, and a step S5 of detecting a vehicle speed from the wheel speed of the vehicle. The output of the wheel vehicle speed detecting means and the output of the wheel vehicle speed detecting means from the output of the ultrasonic vehicle speed detecting means when the road surface traveling is such that the output of the ultrasonic vehicle speed detecting means has sufficient reflection strength such as dry asphalt road surface. The output of the learning means including the routine of step S101 to step S109 and the routine of step S111 to step S115 for learning the relationship and the output of the ultrasonic vehicle speed detection means is not the output of the road surface traveling with sufficient reflection strength such as dry asphalt road surface. At this time, the vehicle speed output of the vehicle 100 is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means. When the vehicle speed output of the vehicle is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means by the switching means including steps S71 to S85 and steps S90 to S94, the learning means The vehicle speed correction means comprising the routines of step S42 and step S54 for correcting the output of the wheel vehicle speed detection means using the result obtained by the above and setting it as the vehicle speed output. Can be used as an example.

The relationship between the ultrasonic vehicle speed detecting means and the wheel vehicle speed detecting means is shown in the table below.

[0079]

[Table 1]

Therefore, particularly on the asphalt road surface where the ultrasonic vehicle speed detecting means of this embodiment is wet with a flooded road surface or rainwater, the reflectance of the submerged road surface is lowered and a reflected wave is generated due to water splash, and the asphalt road surface causes In order not to reduce the vehicle speed detection accuracy due to a decrease in reflectance, which causes an error, the vehicle speed output is used as wheel vehicle speed detection means, and
Learn the relationship between the ultrasonic vehicle speed detection means and the wheel vehicle speed detection means in the normal running state, and correct the vehicle speed value with that relationship,
Maintain reliability of vehicle speed value.

In addition, the vehicle-mounted ultrasonic vehicle speed measuring apparatus of the present embodiment can calculate distances and accelerations by integrating and differentiating the vehicle speed vector, and can be used in the measuring apparatus and the control apparatus. That is, by using the obtained vehicle speed component, the travel distance and the travel direction of the navigation system are corrected, the ABS device, the yaw rate is corrected, and the suspension device for adjusting the vehicle height between the road surface on the left and right wheel sides and the vehicle 100, etc. It can be used for a measuring device and a control device that use various speed information.

By the way, in the above embodiment, the vehicle speeds in two directions are detected by the two ultrasonic wave transmitters / receivers TRF and TRR. However, when the present invention is carried out,
It can be applied to a device having only one ultrasonic wave transmitter / receiver, and since the sound speed is not so high as to be negligible with respect to the vehicle speed, the ultrasonic beam width is narrowed in order to increase the total gain of the wave transmitter / receiver. In this case, the beam during transmission and the beam during reception will be misaligned, so at this time, an ultrasonic wave transmitter / receiver for measuring the vehicle speed during low-speed traveling, and for measuring the vehicle speed during high-speed traveling Alternatively, the ultrasonic wave receiver may receive the reflected wave. Furthermore, in particular, the ultrasonic wave transmitter / receiver that detects the vehicle speed parallel to the traveling direction of the vehicle 100 is two ultrasonic wave transmitters / receivers, or an ultrasonic wave transmitter and an ultrasonic wave receiver,
If the position where the reflected wave is received is changed according to the vehicle speed, highly reliable vehicle speed detection can be performed.

Further, the wheel vehicle speed detecting means of the above embodiment is
Although a known speed sensor is used, when the present invention is carried out, any device that detects the vehicle speed from the wheel speed of the vehicle 100 may be used.

The switching means of the above-mentioned embodiment comprises steps S71 to S85 and steps S90 to S94. In the case of implementing the present invention, the output of the ultrasonic vehicle speed detecting means is dry asphalt. It suffices that the vehicle speed output of the vehicle is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means when the output of traveling on the road surface having sufficient reflection strength on the road surface or the like is lost.

Further, although the learning means of the above-mentioned embodiment comprises the routines of step S101 to step S109 and step S111 to step S115,
In the case of carrying out the present invention, when the output of the ultrasonic vehicle speed detecting means is traveling on a road surface having sufficient reflection strength such as dry asphalt road surface, the output of the ultrasonic vehicle speed detecting means and the output of the wheel vehicle speed detecting means Anything that learns a relationship will do.

Furthermore, the vehicle speed correction means of the above embodiment is
Although it comprises the routine of steps S42 and S54, when the present invention is carried out, the vehicle speed output of the vehicle is switched by the switching means from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means. At this time, it suffices to use the result obtained by the learning means to correct the output of the wheel vehicle speed detecting means and use it as the vehicle speed output.

Although the vehicle speed measurement is described in the embodiment of the present invention, the vehicle-mounted ultrasonic vehicle speed measuring apparatus according to the present invention detects the vehicle speed detected by the vehicle-mounted ultrasonic vehicle speed measuring apparatus. By using the vector component, the navigation system, speed detection device,
It can be used for a measuring device and a control device using various speed information such as a skid prevention device, an ABS device, and a suspension device.

[0088]

As described above, the on-vehicle ultrasonic vehicle speed measuring device according to the first aspect is mounted on a vehicle, transmits an ultrasonic signal to a target, and receives the reflected wave to determine the vehicle speed. An ultrasonic vehicle speed detecting means for detecting and a wheel vehicle speed detecting means for detecting a vehicle speed from the wheel speed of the vehicle are provided, and the road surface traveling in a road surface state in which the output of the ultrasonic vehicle speed detecting means has a sufficient reflection strength. , The vehicle speed output of the vehicle is switched from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means, and the ultrasonic vehicle speed detecting means causes the submerged road surface and the asphalt road surface having fluidity. In order to reduce the accuracy of vehicle speed detection by reducing the reflectance of the submerged road surface, the generation of reflected waves due to water splashes, and the reduction of the reflectance ratio on the asphalt road surface, the vehicle speed output should be adjusted to the vehicle speed. Out as a means to maintain the reliability of the vehicle speed value.

The on-vehicle ultrasonic vehicle speed measuring device of claim 2 is
Ultrasonic vehicle speed detecting means mounted on a vehicle, transmitting an ultrasonic signal to a target and receiving the reflected wave to detect the vehicle speed, and wheel vehicle speed detection for detecting the vehicle speed from the wheel speed of the vehicle Means for outputting the vehicle speed output of the ultrasonic vehicle speed detecting means from the output of the ultrasonic vehicle speed detecting means when the output of the ultrasonic vehicle speed detecting means is no longer an output for road surface traveling in a road surface state having sufficient reflection strength. When the vehicle speed is switched to the output of the vehicle speed detecting means and the road surface traveling is such that the output of the ultrasonic vehicle speed detecting means has a sufficient reflection intensity, the output of the wheel vehicle speed detecting means is changed from the output of the ultrasonic vehicle speed detecting means. By using the result obtained by the learning means for learning the output relationship with, the output of the wheel vehicle speed detecting means is corrected to be the vehicle speed output.

Therefore, when the ultrasonic vehicle speed detecting means has a submerged road surface and an asphalt road surface having a fluid surface, the reflectance of the submerged road surface is lowered, reflected waves are generated by water splash, and the reflectance of the asphalt road surface is lowered. In order not to reduce the accuracy of vehicle speed detection due to error,
The vehicle speed output is used as the wheel vehicle speed detecting means, and furthermore, the relationship between the ultrasonic vehicle speed detecting means and the wheel vehicle speed detecting means is learned in the normal running state, and the vehicle speed value is corrected based on the relationship to maintain the reliability of the vehicle speed value. To do.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic principle of an in-vehicle ultrasonic vehicle speed measuring device according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of an in-vehicle ultrasonic vehicle speed measuring device according to an embodiment of the present invention.

FIG. 3 is a functional configuration diagram of a microcomputer used in a circuit configuration of an in-vehicle ultrasonic vehicle speed measuring device according to an embodiment of the present invention.

FIG. 4 is a flowchart of a part of a main program executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 5 is a flowchart of another part of the main program executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 6 is a flowchart of a timer interrupt processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 7 is a flowchart of a wheel pulse interrupt processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 8 is a flowchart of a wheel speed calculation processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 9 is a flowchart of a vehicle speed calculation processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 10 is a flowchart of a beam mode determination processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 11 is a flowchart of a vehicle speed selection processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 12 is a flowchart of a mileage measurement processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measurement apparatus according to the embodiment of the present invention.

FIG. 13 is a flowchart of a vehicle speed coefficient correction processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 14 is a flowchart of a gate position calculation processing routine executed by the microcomputer of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

FIG. 15 is a timing chart of control of the vehicle-mounted ultrasonic vehicle speed measuring device according to the embodiment of the present invention.

[Explanation of symbols]

 TRF Ultrasonic Transducer TRR Ultrasonic Transducer VCO Voltage Controlled Oscillation Circuit 1 Microcomputer 11 Reception Level Detection Circuit 12 Frequency Detection PLL Circuit FORE Ultrasonic Transmission / Reception Circuit REAR Ultrasonic Transmission / Reception Circuit 100 Vehicle

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

Claims (2)

[Claims] 1. An ultrasonic vehicle speed detecting means mounted on a vehicle for transmitting an ultrasonic signal to a target object and receiving a reflected wave thereof to detect a vehicle speed, and a vehicle speed from a wheel speed of the vehicle. Wheel vehicle speed detecting means for detecting, when the output of the ultrasonic vehicle speed detecting means is no longer the output of road traveling in a state having sufficient reflection strength, the vehicle speed output of the vehicle from the output of the ultrasonic vehicle speed detecting means A vehicle-mounted ultrasonic vehicle speed measuring device, comprising: switching means for switching to an output of a wheel vehicle speed detecting means. 2. Ultrasonic vehicle speed detecting means mounted on a vehicle for transmitting an ultrasonic signal to a target object and receiving the reflected wave to detect the vehicle speed, and the vehicle speed from the wheel speed of the vehicle. Wheel vehicle speed detecting means for detecting, and when the road surface traveling in a state where the output of the ultrasonic vehicle speed detecting means has a sufficient reflection strength, the output of the output of the wheel vehicle speed detecting means from the output of the ultrasonic vehicle speed detecting means Learning means for learning the relationship, when the output of the ultrasonic vehicle speed detecting means is no longer the output of road surface traveling in a state having sufficient reflection strength, the vehicle speed output of the vehicle from the output of the ultrasonic vehicle speed detecting means Switching means for switching to the output of the wheel vehicle speed detecting means, and the learning means when switching the vehicle speed output of the vehicle from the output of the ultrasonic vehicle speed detecting means to the output of the wheel vehicle speed detecting means by the switching means Use fruit by correcting the output of the wheel speed detecting means automotive ultrasonic speed measuring device for it characterized by comprising a vehicle speed correcting means for the vehicle speed output.