JPH0763850A - Vehicle-borne equipment for measuring vehicle speed - Google Patents

Abstract

PURPOSE:To make detection of a vehicle speed possible even when ultrasonic transducers based on a pair beam system fail to operate, by switching over detection outputs of the transducers when the detection output of the ultrasonic transducer or the rear ultrasonic transducer lowers. CONSTITUTION:An ultrasonic wave is transmitted in a prescribed beam width onto a road surface from ultrasonic transducers TRF and TRR for the front and the rear and a reflected wave therefrom is received. A signal detected by a transmission-reception switching circuit 3 is amplified 4, passed through BPF 8 and further amplified 9 and then it is binary-coded by a comparator 10. An output of the comparator 10 is sent to a PLL circuit 12 for frequency detection and a repetition frequency of pulses being proportional to the output is inputted thereby to a microcomputer 1. When a detection output of either one of the transducers TRF and TRR lowers, the detection output of the transducer TRF or TRR is switched over to the detection output of the other and computation of a vehicle speed is executed. When both of the detectors TRF and TRR fail to operate, switchover is made to the vehicle speed detection from wheels by a speed sensor.

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 a vehicle and using various speed information such as a navigation system, a vehicle speed detecting device, an ABS device, etc. The present invention relates to an in-vehicle vehicle speed measuring device used.

[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 speed 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 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 on-vehicle vehicle speed measuring device for transmitting an ultrasonic wave of this kind to a road surface and receiving a reflected wave from the road surface is a wheel vehicle speed detecting means for detecting a vehicle speed from a wheel speed. Compared with, the vehicle speed can be detected without being affected by the air pressure and load of the wheels, tire size, slip, and the like. Furthermore, in order to improve the reliability of the vehicle speed detection,
A forward ultrasonic wave transmitter / receiver that transmits ultrasonic waves with a predetermined depression angle gradient to the traveling direction of the vehicle and receives the reflected waves, and conversely, a predetermined ultrasonic wave transducer with respect to the opposite traveling direction of the vehicle. Vehicle-mounted vehicle speed measuring devices of the pair beam system, which have an ultrasonic wave transmitter / receiver for transmitting an ultrasonic wave with a depression angle and a reflected ultrasonic wave, have been used.

However, if water splashes, muddy splashes, snow, sand, and dust that the vehicle rolls up from the submerged road surface adhere to the ultrasonic transducer, ultrasonic waves may not be output or the output may be reduced. It is expected that correct operation may not be possible.
In particular, in terms of probability, there is a high probability that only one ultrasonic transmitter / receiver will fail.

Therefore, a first object of the present invention is to provide an on-vehicle vehicle speed measuring device capable of detecting the vehicle speed even if one of the ultrasonic transducers of the pair beam system fails.

Further, water splashes and muddy water splashes from the submerged road surface of the vehicle, snow, sand, and dust adhere to the ultrasonic transducer,
If both of the pair-beam type ultrasonic wave transmitters / receivers fail, vehicle speed detection may become impossible.

Therefore, a second object of the present invention is to provide a vehicle-mounted vehicle speed measuring device capable of detecting the vehicle speed even if both of the ultrasonic transducers of the pair beam system are out of order.

[0015]

A vehicle-mounted vehicle speed measuring device according to a first aspect of the present invention transmits an ultrasonic wave with a predetermined depression angle inclination with respect to a traveling direction of a vehicle, and receives a reflected wave from the front side. Ultrasonic wave transmitter / receiver, a rear ultrasonic wave transmitter / receiver that transmits ultrasonic waves with a predetermined depression angle gradient with respect to the anti-travel direction of the vehicle, and receives the reflected wave, and the front ultrasonic wave transmitter / receiver. When the detection output of either the ultrasonic wave transmitter / receiver or the rear ultrasonic wave transmitter / receiver is lowered, the front ultrasonic wave transmission / reception is performed from the detection output of the front ultrasonic wave transmitter / receiver and the rear ultrasonic wave transmitter / receiver. And a switching means for switching the detection output of the ultrasonic wave transmitter / receiver for the rear and outputting the same, and calculating the vehicle speed of the vehicle from the output of the switching means.

An in-vehicle vehicle speed measuring device according to claim 2 is
An ultrasonic wave transmitter / receiver that transmits an ultrasonic wave with a predetermined depression angle gradient with respect to the traveling direction of the vehicle and receives the reflected wave, and a vehicle without relying on the detection output of the ultrasonic wave transmitter / receiver The vehicle speed detecting means for detecting the vehicle speed and the switching means for switching the output to the detection output of the vehicle speed detecting means when the detection output of the ultrasonic transmitter / receiver is lowered are provided, and the vehicle speed of the vehicle from the output of the switching means. Is calculated.

[0017]

According to the first aspect of the present invention, the ultrasonic wave transmitter / receiver for the front, which transmits ultrasonic waves with a predetermined depression angle to the traveling direction of the vehicle and receives the reflected waves, and the anti-progress of the vehicle. The vehicle speed of the vehicle is calculated and the vehicle speed is obtained from the detection output of the rear ultrasonic wave transmitter / receiver that transmits the ultrasonic wave with a predetermined depression angle gradient to the direction and receives the reflected wave. When the detection output of any one of the front ultrasonic wave transmitter / receiver or the rear ultrasonic wave transmitter / receiver is lowered, from the detection output of the front ultrasonic wave transmitter / receiver and the rear ultrasonic wave transmitter / receiver The detection output of the ultrasonic wave transmitter / receiver or the rear ultrasonic wave transmitter / receiver is switched by the switching means, and the vehicle speed of the vehicle is calculated by the detected output to obtain the vehicle speed.

According to a second aspect of the present invention, the vehicle speed of the vehicle is determined by the detection output of the ultrasonic wave transmitter / receiver that transmits the ultrasonic wave with a predetermined inclination to the traveling direction of the vehicle and receives the reflected wave. Is calculated to obtain the vehicle speed. When the detection output of the ultrasonic transducer decreases, the detection output of the vehicle speed detecting means for detecting the vehicle speed of the vehicle without depending on the detection output of the ultrasonic transducer is switched by the switching means, and the detection output , The vehicle speed is calculated to obtain the vehicle speed.

[0019]

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

<Description of Basic Operation> FIG. 1 is a diagram for explaining the basic operation of the vehicle speed measuring device for vehicle according to the embodiment of the present invention. FIG. 1A is a side view of the vehicle speed measuring device for vehicle by the pair beam system.
(B) is a basic operation explanatory view of an in-vehicle vehicle speed measuring device by a pair beam method.

In FIG. 1, a front ultrasonic transducer TRF, which is parallel to the traveling direction of the vehicle 100 and has a depression angle of 45 degrees with respect to the traveling direction, has a predetermined ultrasonic vibration in the 200 [KHz] band. The ultrasonic wave width is transmitted to the road surface and the reflected wave is received, and a vehicle speed (speed vector) VF parallel to the traveling direction of the vehicle 100 is obtained.
Specifically, the front ultrasonic transmitter / receiver TRF is the vehicle 100.
It is located in the front center of the. Rear ultrasonic wave transceiver TR
R has the same characteristics as the front ultrasonic transducer TRF,
The ultrasonic wave is transmitted to the road surface with a predetermined ultrasonic beam width and the reflected wave is received. As shown in FIG. 1 (b),
It is arranged at a position displaced by 180 degrees with respect to the front ultrasonic wave transceiver TRF arranged parallel to the traveling direction of the vehicle 100, and the depression angle is set to 45 degrees with respect to the road surface. The vehicle speed (speed vector) VR is obtained.

The front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR are housed and integrated in a housing B together with a printed circuit board and the like. Then, as shown in FIG. 1B, the housing B is a vehicle 10
0 is attached to the lower surface. The height of the rear ultrasonic wave transmitter / receiver TRR of this embodiment for emitting ultrasonic waves 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) However, Δ 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 performing integration and differentiation of the velocity vector. At this time, the front ultrasonic wave transceiver TRF and the rear ultrasonic wave transceiver TRR are calculated.
The time until the reflected wave arrives varies due to vertical vibration of the vehicle body in the running state of the vehicle, nose up, nose down, and vehicle height changes due to cornering. Therefore, by adjusting the timing of opening the receiving gate for each of the front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR, the target reflected wave is accurately captured, and the Doppler frequency is calculated accordingly. , Get accurate vehicle speed.

<Circuit Configuration of Embodiment> FIG. 2 is a circuit configuration diagram of an in-vehicle 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 front ultrasonic transmitter / receiver TRF transmits and receives ultrasonic vibrations in the 200 [KHz] band with a predetermined ultrasonic beam width. Further, the transmission / reception switching circuit 3 includes a front ultrasonic wave transmitter / receiver T.
Switching is performed when outputting or receiving ultrasonic waves from RF. That is, in the transmission / reception switching circuit 3, the bidirectional diodes ZD1 and ZD2 are turned on at the time of transmission, the signal is output from the ultrasonic transducer TR, and the reception circuit is protected, while the bidirectional diodes ZD1 and ZD2 are received at the time of 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 front ultrasonic transducer TRF to generate ultrasonic waves.

The signal from the front ultrasonic wave transceiver TRF detected through the transmission / reception switching circuit 3 is amplified by the preamplifier 4 and has a reception wave having an ultrasonic frequency that changes in response to speed changes such as vehicle speed. Only the reflected wave 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 changes to 200 ± 50 [KHz] corresponding to the change in speed due to the vehicle speed.
] It is a received wave having a frequency of the order of magnitude, and has a configuration in which the frequency is multiplied in order to detect the frequency in a short time with the required 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. When the reception gate is closed and is not valid, the function as the PLL 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.

This type of front ultrasonic wave transmitter / receiver TRF, transmission / reception switching circuit 3, transformer 5, switching transistor 6, frequency dividing circuit 7 and a transmission circuit system for transmitting ultrasonic waves, and front ultrasonic wave transmission / reception Device TRF, transmission / reception switching circuit 3, preamplifier 4, bandpass filter 8, amplifier 9, comparator 10, reception level detection circuit 11, frequency detection P
An ultrasonic wave transmitting / receiving circuit FORE is constituted by the LL circuit 12 and a receiving circuit system for receiving ultrasonic waves.

The ultrasonic transmission / reception circuit REAR using another rear 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 is a functional configuration diagram of the microcomputer 1 used in the circuit configuration of the vehicle-mounted vehicle speed measuring device according to the embodiment of the present invention.

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.

A microcomputer 1 for transmitting an intermittent ultrasonic wave every 10 [msec] from the front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR for a frequency of 200 [KHz] and a duration of 1 [msec]. A gate signal for intermittent output is output from the terminal P1 of the parallel port 107 of FIG. The switching transistor 6 is turned on / off by the output of the frequency dividing circuit 7, and ultrasonic waves are generated from the front ultrasonic transducer TRF and the rear ultrasonic transducer 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 front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR may be output simultaneously or in a time division manner. In the case of the present embodiment, since the opening is large and the possibility of mutual interference is low, the ultrasonic waves are transmitted from the front ultrasonic wave transceiver TRF and the rear ultrasonic wave transducer TRR at the same time.

When the front ultrasonic transmitter / receiver TRF (rear ultrasonic transmitter / receiver TRR) receives the reflected wave from the road surface, the preamplifier 4 amplifies the gain to about 80 [dB] and Approximately 200 ± 50 [KH by pass filter 8
z] signal is taken out, further amplified, then binarized by the comparator 10, and the frequency detection PLL
It is input to the circuit 12 and the frequency of the reflected wave from the road surface is detected. The output of the comparator 10 is a frequency detection PL
The L circuit 12 performs sampling and holding for a time period for detecting a specific reflected wave from the road surface, and holds the voltage thereof to hold a specific detection frequency of the reflected wave from the road surface. The output of the voltage controlled oscillator VCO is 1/8
And the frequency is fed back to the phase difference detection circuit PD, whereby the front ultrasonic transducer TR is transmitted.
It is designed to be locked at a frequency that is eight times as high as the reflection frequency input to F (rear ultrasonic transducer TRR).
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 transmission / reception circuit REAR operates in the same manner, but the explanation of the operation will be omitted because it is redundant.

4 and 5 are flow charts of the main program executed by the microcomputer 1 of the vehicle speed measuring device for vehicle according to the embodiment of the present invention. 6 is a flowchart of a timer interrupt processing routine, FIG. 7 is a flowchart of a wheel pulse interrupt processing routine, FIG. 8 is a flowchart of a wheel speed calculation processing routine, and FIG. 9 is a flowchart of a vehicle speed calculation processing routine. 11 is a flowchart of a beam mode determination processing routine, FIG. 11 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. It is a flow chart of a position calculation processing routine. Also,
FIG. 15 is a timing chart of control of the vehicle-mounted 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 supply (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
In step 5, a wheel speed calculation processing routine as a vehicle speed detecting means including a known speed sensor that detects the vehicle speed from the wheel speed of the vehicle 100 is called. In step S6, the switching transistor 6 is turned on and the ultrasonic wave transmitting / receiving circuit FOR is
E, open the transmission gate of the ultrasonic transmission / reception circuit REAR, and judge the lapse of 1 msec by the main timer T in step S7,
In step S8, the transmission gates of the ultrasonic transmission / reception circuit FORE and the ultrasonic transmission / reception circuit REAR are closed. This gives 1
A burst signal of ultrasonic waves of [msec] will be output. That is, as shown in FIG. 15, steps S5 to S8 open and close the transmission gate.
The output terminal P1 of the frequency dividing circuit 2 outputs "1" every 10 [msec] for 1 [msec].
It becomes the burst signal shown in, and the ultrasonic transducer for front TR
The transmission input of L and the rear ultrasonic wave transmitter / receiver TRR becomes like the output e2. The reflected wave becomes an output e3 via the front ultrasonic wave transmitter / receiver TRL or the rear ultrasonic wave transmitter / receiver TRR.

Up to this point, when ultrasonic waves are transmitted, the ultrasonic wave transmission / reception circuit FORE, the ultrasonic wave transmission / reception 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 vehicle speed 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 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 calculation unit 101. And step S4
In 1, the input port determines whether or not the signal is noise, and when it is not noise, the value of the speed conversion count Nd for each interrupt is given to the interrupt counter Np that counts the number of interrupts in 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 speed conversion count 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 is converted into the vehicle speed Vw by using the value of the interrupt counting counter Np storing the output from the speed sensor.

<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 on the FORE side, that is, the traveling direction, 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
When the vehicle speed becomes faster in step 3, the output is reduced, which is corrected. In step S64, the "beam mode determination process" routine is called, in step S65, the "vehicle speed selection process" routine is called, and in step S66 "running". Call the "distance measurement process" routine and exit this routine.

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, the value obtained by subtracting the memory Ar from the memory Af in step S74 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 only one reception level Ev is determined. If the value is large, there is a possibility that the vehicle height has changed due to vertical vibration of the vehicle body, nose up, nose down, or cornering. Therefore, in order to select a reliable reception level Ev value, the mode designation The value of the mode determination internal flag Fm corresponding to the state is stored in the memory BMOD.

<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 front ultrasonic wave transceiver TRF side is large, so that the vehicle speed V is set to the FORE side in step S92. The vehicle speed is VF. 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 rear ultrasonic wave transceiver TR R side is large.
In step S93, 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 on the rear ultrasonic transducer TRR side and the output level on the front ultrasonic transducer TRF side are low. Since it cannot be used, the vehicle speed V is set to the vehicle speed Vw obtained from a known speed sensor in step S94.

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, if only one of the reception levels Ev is large, there is a possibility that vertical vibration of the vehicle body, nose up, nose down, and vehicle height change due to cornering may occur, which is highly reliable. In order to select the reception level Ev side, the vehicle speed V is determined according to the contents of the mode designation memory BMOD. When the output on the side of the rear ultrasonic wave transmitter / receiver TRR and the output on the side of the front ultrasonic wave transmitter / receiver TRF cannot be used, the vehicle speed V is set to the vehicle speed Vw obtained from a known speed sensor.

<Running Distance Measurement Processing (See FIG. 12)> This routine is executed in step S10 when the "running distance measurement processing" routine is called in 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, in step S107, it is determined whether or not the traveling distance for the unit short time Δt stored in the memory LSS exceeds 2 [km]. If not, this routine is exited. When it is determined that the traveling distance for the unit short time Δt stored in the memory LSS exceeds 2 [km], the "vehicle speed coefficient correction process" routine is called to correct the vehicle speed coefficient in step S108, and the flag FBMOB is called in step S109. Take off.

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
−LSS) / LSPS} × 100 is used to calculate the error rate Err, and it is determined in step S112 and step S113 whether the error rate Err exceeds 0.2% set as the threshold value or falls below −0.2%. , When the error rate Err exceeds 0.2%, Nd (initial value = 363) is set to “−” in step S114.
1 "is subtracted, and when the error rate Err is less than -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 vehicle speed measuring apparatus according to the present embodiment transmits the ultrasonic wave with a predetermined depression angle gradient with respect to the traveling direction of the vehicle 100 and receives the reflected wave for the front ultrasonic wave. The ultrasonic wave transmitter / receiver TRF, the ultrasonic wave transmitter / receiver TRR for the rear, which transmits the ultrasonic wave with a predetermined depression angle gradient with respect to the anti-traveling direction of the vehicle 100, and receives the reflected wave, and the front wave transmitter / receiver TRR. Ultrasonic transducer TRF or rear ultrasonic transducer TR
When the detection output of any one of R decreases, the front ultrasonic transducer TRF and the rear ultrasonic transducer TRR
From the detection output of step S61 to step S63 and step S64 (steps S71 to S85) for switching to the detection output of the front ultrasonic transducer TRF or the rear ultrasonic transducer TRR. It is provided with the switching means and the calculating means including the routine of steps S90 to S93 for calculating the vehicle speed from the output of the switching means, which can be the embodiment of claim 1.

Therefore, the front ultrasonic wave transmitter / receiver TRF
, The rear ultrasonic wave transmitter / receiver TRR intermittently transmits an ultrasonic signal to the road surface like the output e2, receives the reflected wave to form a signal e3, and amplifies the received signal e3, The amplified signal is input to the sampling and holding resistor R and the capacitor C, the sampled and held signal is voltage / frequency converted by the voltage controlled oscillator circuit VCO, and the frequency proportional to the reflected wave is input to the microcomputer 1 to determine the vehicle speed. obtain. At this time, the front ultrasonic transducer TRF
If the rear ultrasonic transducer TRR is operating correctly, in step S91, the vehicle speed V should be a simple average of the vehicle speed VF on the FORE side and the vehicle speed VR on the REAR side (VF + V).
R) / 2 is used to obtain the average vehicle speed, which is referred to as vehicle speed V. At this time, the vehicle speed can be detected without being affected by the air pressure and load of the wheels, tire size, slip, and the like.

To one of the front ultrasonic wave transceiver TRF or the rear ultrasonic wave transceiver TRR, water splashes or muddy water splashes from the submerged road surface, snow, sand or dust adheres, and ultrasonic waves are output. No output, or the output is reduced and it is not possible to operate correctly, or the output is generated due to an abnormality such as a disconnection of the circuit of the front ultrasonic transducer TRF or the rear ultrasonic transducer TRR. If not, step S9
The vehicle speed V is set to the vehicle speed VF on the FORE side in 2 or the vehicle speed V is set to the vehicle speed VR on the REAR side in step S93. Therefore, even if one of the front ultrasonic transducer TRF and the rear ultrasonic transducer TRR has a reduced output due to a failure or the like, the tire air pressure and load, tire size,
The vehicle speed can be detected without being affected by slip or the like.

Of course, even when there is a possibility that the height of the vehicle body may be vertically vibrated, the nose up, the nose down, or the vehicle height may be changed due to cornering due to the unevenness of the road surface or the like, the side of the highly reliable reception level Ev 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.

Further, the vehicle-mounted vehicle speed measuring device of this embodiment is
A front ultrasonic wave transceiver TRF that transmits an ultrasonic wave with a predetermined depression angle to the traveling direction of the vehicle 100 and receives the reflected wave, and a predetermined ultrasonic wave transceiver TRF for the opposite traveling direction of the vehicle 100. The detection output of the rear ultrasonic transducer TRR that transmits ultrasonic waves with a depression angle gradient and receives the reflected waves, and the front ultrasonic transducer TRF and the rear ultrasonic transducer TRR. When the detection outputs of both the vehicle speed detecting means including a speed sensor for detecting the vehicle speed of the vehicle 100 without relying on it and the front ultrasonic wave transceiver TRF and the rear ultrasonic wave transceiver TRR are lowered, Step S61 to Step S63 and Step S64 (Step S71 to Step S73, Step S86 and Step S8) for switching the output to the detection output of the vehicle speed detecting means.
It comprises a switching means comprising the routine of 7) and a computing means comprising the routines of step S90 and step S94 for computing the vehicle speed from the output of the switching means, which corresponds to the embodiment of claim 2.

Therefore, in this embodiment, step S7
When the reception level Ev of the FORE side stored in the memory Af of the pair beam system and the reception level Ev of the REAR side stored in the memory Ar are equal to or more than a predetermined value in 3 and the sum of both reception levels Ev is small , The water splashes and muddy water splashes from the submerged road surface, snow, sand, dust are attached, ultrasonic waves are not output, or the output is reduced, it is impossible to operate accurately, Alternatively, it is determined that the output cannot be generated due to an abnormality such as a disconnection of the circuits of the front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR, and the vehicle speed V is detected by the vehicle speed detecting means including a speed sensor in step S94. Vw. Therefore, the front ultrasonic transducer TRF and the rear ultrasonic transducer TR
When both R are out of order due to a failure or the like, the vehicle speed can be detected by the vehicle speed Vw of the vehicle speed detecting means including the speed sensor, and the reliability of the vehicle speed value can be improved.

Of course, it is specified that the detection level of the reflected wave from the road surface is lowered during traveling on the asphalt road surface where water or the like is adhered to the submerged road surface, and the reflectance of the submerged road surface is reduced and diffuse reflection due to water splashes is specified. It is possible to improve the reliability of vehicle speed detection by preventing the occurrence of noise and the decrease in reflectance due to the asphalt road surface with water adhering to the surface causing an error, and switching to the output of the vehicle speed detection means consisting of a speed sensor. it can.

By the way, in the present embodiment, when both the detection outputs of the pair-beam type front ultrasonic wave transmitter / receiver TRF and the rear ultrasonic wave transmitter / receiver TRR decrease, the vehicle speed V is detected by the vehicle speed detecting means including a speed sensor. Although the vehicle speed is set to Vw, when the present invention is carried out, the invention is not necessarily limited to the pair beam system, and may be applied to the single beam system.

In this case, the vehicle-mounted vehicle speed measuring device of the embodiment is
An ultrasonic wave transmitter / receiver TRF for the front side or an ultrasonic wave transmitter / receiver TRR for the rear side which transmits an ultrasonic wave with a predetermined depression angle to the traveling direction of the vehicle 100 and receives the reflected wave. When the detection output of the ultrasonic wave transceiver, the vehicle speed detecting means including a speed sensor or the like for detecting the vehicle speed of the vehicle 100 without depending on the detection output of the ultrasonic wave transceiver, and the detection output of the ultrasonic wave transceiver is lowered, Steps S61 to S63 for switching the output to the detection output of the vehicle speed detection means,
Step S64 (Steps S71 to S73,
3. An embodiment according to claim 2, comprising switching means comprising a routine of steps S86 and S87) and computing means comprising a routine of steps S90 and S94 for computing the vehicle speed from the output of the switching means. It is also possible to have a configuration of

That is, in the present embodiment, the vehicle speeds in two directions are detected by the two front ultrasonic wave transmitters / receivers TRF and the rear ultrasonic wave transmitter / receivers TRR. It can be applied to a device having only one ultrasonic wave transmitter / receiver, and the sound speed is not so high as to be negligible with respect to the vehicle speed. If it is narrowed, the beam during transmission and the beam during reception will be misaligned.Therefore, at this time, the ultrasonic wave transmitter / receiver for measuring the vehicle speed during low speed traveling and the vehicle speed during high speed traveling For this purpose, the reflected wave may be received by the ultrasonic wave receiver. 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, and the ultrasonic wave transmitter / receiver is used depending on the vehicle speed. And change the position to receive the reflected wave,
The vehicle speed can be detected with high reliability.

Further, in the vehicle speed detecting means of the above-mentioned embodiment, the vehicle speed is detected when both the front ultrasonic wave transceiver TRF and the rear ultrasonic wave transducer TRR are out of order due to a failure or the like. Although the speed sensor is used in the above, it is premised that the probability of occurrence of a situation like that of the embodiment of the present invention is set to be equal to none, so that it is simulated by the output from the engine rotation sensor and the gear position. The vehicle speed may be calculated. That is, the vehicle speed detecting means for carrying out the present invention may be any one that detects the vehicle speed from the vehicle 100 without depending on the detection output of the ultrasonic wave transmitter / receiver.

The switching means of each of the above embodiments is the ultrasonic transducer for front TRF or the ultrasonic transducer for rear TR.
When any one of the detection outputs of R is lowered, it is detected in step S61 to switch to the detection output of the front ultrasonic wave transceiver TRF or the rear ultrasonic wave transducer TRR and output it. The microcomputer 1 includes the routine of step S63 and step S64 (steps S71 to S85). However, the present invention is not limited to this, and any one of the detection outputs Can be configured as a detection circuit and a switch circuit for detecting a decrease in the voltage.

Further, the calculating means of each of the above embodiments is the vehicle 1
Step S90 to Step S9 for calculating the vehicle speed of 00
However, when the present invention is carried out, the present invention is not limited to this, and the vehicle speed V may be calculated from the output selected by the switching means.

Further, the vehicle-mounted vehicle speed measuring device of each of the above-mentioned embodiments can finally calculate the distance and the acceleration by integrating and differentiating the vehicle speed vector, and can be used for the measuring device and the control device. That is, by using the obtained speed component, various speed information such as the correction of the travel distance and the travel direction of the navigation system, the ABS device, the suspension device for adjusting the vehicle height between the left and right wheel-side road surfaces and the vehicle 100, etc. It can be used for measuring devices and control devices that use

[0091]

As described above, the vehicle speed measuring device for vehicle according to the first aspect transmits the ultrasonic wave with a predetermined depression angle gradient with respect to the traveling direction of the vehicle, and receives the reflected wave. The ultrasonic wave transmitter / receiver for the vehicle and the ultrasonic wave transmitter / receiver for the rear, which transmits the ultrasonic wave with a predetermined depression angle gradient with respect to the anti-travel direction of the vehicle and receives the reflected wave, The vehicle speed is calculated to obtain the vehicle speed. Then, when the detection output of any one of the front ultrasonic wave transmitter / receiver or the rear ultrasonic wave transmitter / receiver is lowered, from the detection output of the front ultrasonic wave transmitter / receiver and the rear ultrasonic wave transmitter / receiver By switching to the detection output of the front ultrasonic wave transmitter / receiver or the rear ultrasonic wave transmitter / receiver by the switching means, the vehicle speed is calculated from the detection output.
The vehicle speed can be detected even if one of the ultrasonic transducers of the pair beam system fails.

The on-vehicle vehicle speed measuring device according to the second aspect of the invention detects the output of an ultrasonic wave transmitter / receiver that transmits ultrasonic waves with a predetermined depression angle gradient with respect to the traveling direction of the vehicle and receives the reflected waves. Thus, the vehicle speed of the vehicle is calculated to obtain the vehicle speed. When the detection output of the ultrasonic transducer decreases, the switching means switches to the detection output of the vehicle speed detecting means for detecting the vehicle speed of the vehicle without depending on the detection output of the ultrasonic transducer, and the detection is performed. Since the vehicle speed is obtained by calculating the output, the vehicle speed can be detected even if both of the pair-beam ultrasonic transducers or the single-beam ultrasonic transducers fail.

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 TRF Front ultrasonic transmitter / receiver TRR Rear ultrasonic transmitter / receiver VCO Voltage control 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 vehicles

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

Claims (2)

[Claims] 1. A front ultrasonic wave transmitter / receiver for transmitting an ultrasonic wave with a predetermined depression angle with respect to a traveling direction of a vehicle and receiving a reflected wave thereof, and to an anti-traveling direction of a vehicle. A rear ultrasonic wave transceiver that transmits an ultrasonic wave with a predetermined depression angle gradient and receives the reflected wave, and either one of the front ultrasonic wave transceiver or the rear ultrasonic wave transceiver When the detection output of decreases, by switching from the detection output of the front ultrasonic transmitter / receiver and the rear ultrasonic transmitter / receiver to the detection output of the front ultrasonic transmitter / receiver or the rear ultrasonic transmitter / receiver, An in-vehicle vehicle speed measuring device comprising: a switching means for outputting it and a computing means for computing the vehicle speed of the vehicle from the output of the switching means. 2. An ultrasonic wave transmitter / receiver for transmitting an ultrasonic wave with a predetermined depression angle gradient with respect to the traveling direction of a vehicle and receiving a reflected wave thereof, and a detection output of the ultrasonic wave transmitter / receiver. Vehicle speed detection means for detecting the vehicle speed of the vehicle without depending, switching means for switching the output to the detection output of the vehicle speed detection means when the detection output of the ultrasonic transducer decreases, and vehicle output from the output of the switching means An in-vehicle vehicle speed measuring device, comprising: a calculating unit that calculates the vehicle speed of the vehicle.