JPH07280936A - Ultrasonic transmitter-receiver - Google Patents

Abstract

PURPOSE:To judge the existence of external ultrasonic waves regarding an ultrasonic transmitter-receiver which is suitable for a measurement based on the Doppler shift of an ultrasonic frequency in surroundings in which the external ultrasonic waves exist. CONSTITUTION:When a damping flag and a sensor correction flag are turned off, an element for ultrasonic transmission-reception is turned off (Steps 140 to 144). Whether a received signal exists or not is judged after the reverberation time of a transmitter has elapsed, and, when the signal exists, an external-noise warning flag is turned on (Steps 146 to 152). When the flag is turned on, an element for transmission is not turned on until the set time of a normal return timer (Step 156) elapses (Step 158) even when the damping flag or the sensor correction flag is turned on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transmitter / receiver, and more particularly to an ultrasonic transmitter / receiver suitable for performing measurement based on the Doppler shift of the ultrasonic frequency in an environment where an external ultrasonic wave exists.

[0002]

2. Description of the Related Art Conventionally, there have been known devices for making various measurements by utilizing the Doppler shift of the frequency generated in the propagation path of ultrasonic waves. For example, JP-A-59-203973
The publication discloses a ground vehicle speed sensor which measures the vehicle speed using the above principle.

This ground speed sensor has a structure in which an ultrasonic wave transmitter and receiver are mounted separately from each other in the longitudinal direction of the vehicle, and the ultrasonic wave reflected wave emitted from the transmitter toward the road surface is received by the receiver. Is.

According to this structure, the ultrasonic wave received by the receiver is superposed with the displacement speed in the vehicle front-rear direction, that is, the Doppler shift corresponding to the vehicle speed. By comparing the frequency of the ultrasonic wave received by the receiver, the vehicle speed can be detected.

[0005]

However, various ultrasonic wave sources exist in the outside world, and for example, in a running vehicle, a ground speed sensor mounted on another vehicle, an exhaust pipe of a two-wheeled vehicle, ultrasonic raindrop removal. Ultrasonic waves generated from a functional vehicle side mirror or the like are propagated. When such an extraneous ultrasonic wave is present, an error caused by the extraneous ultrasonic wave is superimposed on the detection value of the conventional ground vehicle speed sensor.

The present invention has been made in view of the above points, and in addition to the normal operating state in which both the ultrasonic transmitter and the receiver are operated, the transmitter is stopped and only the receiver is operated. It is an object of the present invention to provide an ultrasonic wave transceiver that determines the existence state of an external ultrasonic wave by forming a state and thereby solves the above problems.

[0007]

FIG. 1 shows the principle configuration of an ultrasonic transmitter / receiver which achieves the above object. That is,
The above-mentioned object is, as shown in FIG. 1, an ultrasonic wave provided with a transmitter M1 for transmitting ultrasonic waves to an object and a receiver M2 for receiving ultrasonic waves originating from the transmitter M1. In the transceiver, a first operating state in which both the transmitter M1 and the one receiver M2 are activated and a second operating state in which the transmitter M1 is stopped and only the receiver M2 is activated are realized. This is achieved by an ultrasonic transmitter / receiver including an operating state switching means M3 and an external ultrasonic wave determining means M4 for determining the presence of an external ultrasonic wave based on the receiving state of the receiver M2 under the second operating state. .

Further, in the ultrasonic transmitter / receiver having the above structure, when the presence of the foreign ultrasonic wave is judged by the foreign ultrasonic wave judging means M4, a fail preventing means for carrying out a process for preventing a failure due to the foreign ultrasonic wave is performed. An ultrasonic transceiver equipped with M5 is also effective.

Further, in the ultrasonic transmitter / receiver having the above-mentioned configuration, the occurrence state of the external ultrasonic wave is detected based on at least one of the interval time and the duration time at which the external ultrasonic wave is detected by the external ultrasonic wave discrimination means M4. External ultrasonic wave generation status detecting means M7, and when the operating status switching means M3 returns from the second operating status to the first operating status based on the detection result of the external ultrasonic wave generation status detecting means M7. An ultrasonic transmitter / receiver that is a means for determining the delay time and is provided with a return delay means M7 that determines the delay time longer as the occurrence status of the external ultrasonic waves is more frequent is also effective.

[0010]

In the first aspect of the ultrasonic transceiver according to the present invention, when the operating state switching means realizes the second operating state, the receiver M2 includes the transmitter M1 as a source. The ultrasonic waves to be received are not received.

Therefore, under the second operating condition, the receiver M2 receives only the external ultrasonic wave when the external ultrasonic wave exists, and does not receive any ultrasonic wave when the external ultrasonic wave does not exist. Is not received.

The external ultrasonic wave discrimination means M4 is
Based on the ultrasonic wave reception state of the receiver M2 under the second operation state, it is determined that an external ultrasonic wave is present when any ultrasonic wave is received, and no ultrasonic wave is received. In this case, it is determined that there is no external ultrasonic wave.

On the other hand, when the operation state switching means realizes the first operation state, the ultrasonic wave generated by the transmitter M1 is detected in the receiver M2, and the ultrasonic wave generated by the transmitter M1 is detected in the ultrasonic wave generated by the transmitter M1. External ultrasonic waves that do not depend on operation are received.

At this time, if the external ultrasonic wave discriminating means M4 determines that no external ultrasonic wave is present, the desired physical quantity based on the Doppler shift amount can be detected with high accuracy based on the received signal from the receiver M2. When it is determined that the external ultrasonic waves are present, it is recognized that the influence of the external ultrasonic waves is superimposed on the detection result.

The second aspect of the ultrasonic transceiver according to the present invention
In the above aspect, the fail prevention unit M5 executes a predetermined fail prevention process when the external ultrasonic wave determination unit M4 determines that the external ultrasonic wave is present. Therefore, even when the first operating state is realized in the presence of external ultrasonic waves, malfunction due to the influence of external ultrasonic waves is prevented.

Furthermore, the third embodiment of the ultrasonic transceiver according to the present invention.
In the above aspect, the occurrence frequency detection means M6 detects the frequency with which the external ultrasonic wave determination means M4 determines the presence of external ultrasonic waves. The return delay means M7 determines the return delay time from the second operating state to the first operating state to be longer as the frequency is higher.

Therefore, in the environment where the ultrasonic transmitter / receiver is placed, if the external ultrasonic waves are frequently generated or if the external ultrasonic waves are continuously generated for a long period of time, the first operation is performed. The easy return to the state is suppressed.

[0018]

FIG. 2 is a block diagram showing the configuration of an on-vehicle ground vehicle speed sensor which is an embodiment of the ultrasonic transceiver according to the present invention.

In the figure, a transmitter 10 and a receiver 12
Are ultrasonic transmitters and receivers which are respectively arranged in the vehicle front-rear direction with a predetermined distance therebetween. Here, the positional relationship between the transmitter 10 and the receiver 12 is adjusted so that the reflected wave of the ultrasonic wave 16 emitted from the transmitter 10 toward the road surface 14 is propagated to the receiver.

An oscillator 20 is connected to the transmitter 10 via a drive circuit 18, and a frequency control circuit 22 is connected to the oscillator 20. Here, frequency control circuit 2
Reference numeral 2 is a circuit that controls the oscillation frequency of the oscillator 20 to a predetermined frequency. That is, the transmitter 10 is controlled by the frequency control circuit 22 to a predetermined frequency, and the drive circuit 18 is controlled.
Thereby, the ultrasonic signal amplified to a signal of a predetermined power is supplied.

A mixing circuit 26 is connected to the receiver 12 via a preamplifier 24. Further, the oscillator 20 described above is further connected to the mixing circuit 26. The mixing circuit 26 is a circuit that mixes the reflected wave of the ultrasonic wave 16 received by the receiver 12 and the ultrasonic signal supplied to the transmitter 10 to generate an output signal corresponding to the frequency difference between the two. .

Here, as described above, the transmitter 10 and the receiver 12 are arranged at a predetermined distance in the vehicle front-rear direction. According to such an arrangement, when the vehicle is stopped, the frequency of the ultrasonic wave emitted by the transmitter 10 and the frequency of the ultrasonic wave received by the receiver 12 are equal, but when the vehicle speed occurs in the vehicle, the ultrasonic wave is generated between them. The frequency difference corresponding to the vehicle speed is superimposed.

Therefore, the frequency difference signal formed by the mixing circuit 26 as described above corresponds to the vehicle speed of the vehicle equipped with the ground vehicle speed sensor. In the present embodiment, the frequency difference signal of the mixing circuit 26 is supplied to the vehicle speed calculation circuit 30 via the low pass filter 28, and the vehicle speed calculation circuit 30 calculates the ground vehicle speed.

An external ultrasonic wave detection circuit 32 is connected to the preamplifier 24 in addition to the above-mentioned mixing circuit 26. The extraneous ultrasonic wave detection circuit 32 is a main part of the present embodiment which realizes the above-mentioned operating state switching means M3, the extraneous ultrasonic wave discrimination means M4, etc. by executing the processing described later.

That is, the external ultrasonic wave detection circuit 32 appropriately issues an operation signal or a stop command to the oscillator 20 and the vehicle speed calculation circuit 30 in accordance with the processing described later to form the above-mentioned first and second operation states.

In this embodiment, the operating state of the brake is monitored as the basis for determining the switching of the operating state, and therefore the external ultrasonic wave detection circuit 32 is used.
A brake switch 36 that outputs an ON signal when the brake pedal 34 is depressed is connected to the.

3 to 8 are flowcharts of the main routine executed by the external ultrasonic wave detection circuit 32 in this embodiment. The operation of the ground vehicle speed sensor of this embodiment will be described below with reference to the drawings. It should be noted that this routine is a regular interruption routine that is started at the same time as the start of the vehicle and the processing excluding the initialization processing is repeatedly executed every predetermined time.

Steps 100 and 102 shown in FIG.
Both are steps for executing an initialization process which is executed only immediately after starting. That is, in step 100, the braking flag and the external noise warning flag, which will be described later, are turned off, and the processing for clearing the external noise duration Tx and the fail interval timer Ts to "0" is performed.
In step 102, a sensor correction cycle timer Ti, which will be described later, is set to an initial value K1 and the sensor correction flag is turned off.

After the above processing is completed, next step 10
Then, the routine proceeds to step 4 to judge from the state of the brake switch 36 whether the brake is on. The ground vehicle speed sensor of this embodiment is assumed to be used in combination with an antilock brake system (ABS) known as a vehicle braking device, and is provided for the purpose of accurately detecting the vehicle speed when the wheels are locked. This is because the processing contents differ depending on whether or not the brake is operated.

That is, when it is determined in step 104 that the brake is on (the brake is being operated), the process proceeds to step 106, the braking flag is turned on to indicate the state, and then, in step 108, the braking flag holding counter. Substitute the initial value K2 for Tb.

After the brake is turned off, this K2 is
This means a delay time for keeping the braking flag in the on state, and as long as the brake is on, step 104
Each time is executed, K2 is repeatedly substituted.

When the brake operation is completed and the brake switch 36 is turned off, the condition of step 104 is not satisfied, and step 110 is executed thereafter. Step 110 is a step of determining whether or not the braking flag is on. If the braking operation is performed once as described above, the braking flag is on, so that step 112 is subsequently executed.

In step 112, the braking flag holding counter Tb is decremented, and the process of decrementing the set K2 as the initial value is performed as described above. Thereafter, in step 114, it is determined whether or not Tb has reached "0", and if Tb = 0 is satisfied, step 116 is performed.
In, processing for turning off the braking flag is performed.

On the other hand, if the accuracy flag is off during the execution of the step 110, the steps 112 to 112 are executed.
116, and if Tb = 0 is determined in step 114, step 114 is skipped.

FIG. 9 shows a change in the state of the braking flag realized by the steps 104 to 116. The braking flag in this routine is as shown in FIG. 9 when the braking operation is started (see FIG. 9). During time t ₁ ), it is turned on, and after the brake operation is completed, it waits for K2 to elapse (time t _{2 in} FIG. 9) and then turned off.

After the processing for setting the braking flag as described above is completed, the routine proceeds to step 118 shown in FIG. 4, where it is judged if the sensor correction cycle timer Ti = 0 is satisfied. This Ti is a timer that is set to count the execution timing of the sensor correction that is periodically executed to maintain the detection accuracy of the ground vehicle speed sensor, and K1 is substituted by the initialization as described above.

Therefore, if it is the first time that step 118 is executed, Ti = 0 is not established, and then T = 0.
Step 120 of decrementing i is performed. In this case, the sensor correction flag is further turned off in step 122, and in the following step 124, a process of substituting the initial value K3 into the sensor correction flag holding counter Th described later is performed.

Thereafter, when this routine is started, until it is judged at step 118 that Ti = 0 is satisfied,
The above steps 120, 122 and 124 are repeatedly executed. As a result, the sensor correction flag is maintained in the off state until Ti = 0 is satisfied, and the value of the sensor correction flag holding counter is always held at K3.

When it is judged at step 118 that Ti = 0 is satisfied, the routine proceeds to step 126, where it is judged if the braking flag is on. As described above, the braking flag is turned on at the time when the vehicle speed should be detected by the ground vehicle speed sensor in this embodiment. Therefore, when such a request is made, the vehicle speed detection is prioritized over the sensor correction. This is to determine whether or not the request is made.

Therefore, only when it is determined in step 126 that the braking flag is not on, the routine proceeds to step 128, the sensor correction flag is turned on, and preparations for executing the sensor correction are started.

Here, the correction of the vehicle speed sensor to ground needs to be performed after operating both the transmitter 10 and the receiver 12 and actually receiving the ultrasonic wave generated by the transmitter 10 by the receiver 12. However, from the start of operation of the transmitter 10 and the receiver 12 to the formation of a stable transmission / reception state,
It usually takes some time.

The sensor correction flag holding counter T described above.
h is a counter provided for counting the time required for stabilizing the transmission / reception, and when the sensor correction flag is turned on as described above, it is decremented in step 130. Then, when Th in which K3 is set as the initial value becomes "0" (see step 124 above), a trigger is issued to execute the sensor correction as described later.

That is, as shown in FIG. 10, Ti = 0
Is not satisfied ((A) in the same figure), Th is held at K3 ((B) in the same figure), and when Ti = 0 is satisfied, the sensor correction flag is turned on ((C) in the same figure) and Th When decrementing is started and then Th = 0 is satisfied, a sensor correction trigger is issued.

In this case, in this routine, the transmitter 1 is activated when the sensor correction flag is turned on as described later.
It is supposed that the transmission of ultrasonic waves by 0 is started. Therefore, by the time Th is decremented from K3 to 0, that is, when the sensor correction trigger is issued,
A stable transmission / reception state can be secured.

By the way, after Th becomes 0 as shown in FIG. 10, the above-mentioned processing is repeated again in order to realize the sensor correction after a predetermined period. Therefore, following the processing of step 130, it is determined in step 132 whether Th = 0 is satisfied, and if the condition is satisfied, step 13 is performed.
In step 4, the process of substituting the initial value K1 for Ti is performed.

If the braking flag is turned on before Th = 0 is satisfied, the vehicle speed detection by the ground vehicle speed sensor should be executed prior to the sensor correction. If it is determined that is ON, then the routine proceeds to step 136, where the sensor correction flag is turned off, and then at step 138 a process of substituting the initial value K1 into the sensor correction cycle timer Ti is performed.

Therefore, when the braking flag is turned on as shown in FIG. 10 (D), regardless of the state of Th, T
i, Th, and the sensor correction flag are all reset to the initial state.

Hereinafter, according to the states of the braking flag and the sensor correction flag set as described above, the vehicle speed detection by the ground vehicle speed sensor, the sensor correction of the ground vehicle speed sensor, and the extraordinary operation which is a characteristic operation of this embodiment. Determine the presence of sound waves.

That is, when the processing shown in FIG. 4 is completed, the routine proceeds to step 140 shown in FIG. 5 to determine whether the braking flag is on. If the braking flag is not on, the routine proceeds to step 142, where it is judged if the sensor correction flag is on.

In this case, if both of them are not turned on, it can be determined that the ground vehicle speed sensor is not substantially required to operate, and in this embodiment, the presence / absence of an external ultrasonic wave is determined in such a situation. I am going to do it.

That is, the above steps 140 and 14
If it is determined in step 2 that neither flag is on, the routine proceeds to step 144, where the oscillation of the oscillator 20 is stopped to turn off the operation of the transmitting element of the transmitter 10.

Next, at step 146, it is judged whether or not the delay timer after transmission OFF Td is "0", and Td =
If 0 is not established, the routine proceeds to step 148, where Td is decremented. Delay timer Td after this transmission is turned off
Is set in consideration of the time required for the reverberation of the transmitter 10 to disappear after the oscillation stop command is issued to the oscillator 20, and the initial value K4 is set during the operation of the transmitter 10 as described later. Is set to.

Thereafter, in step 146, Td =
The step 148 is repeatedly executed until 0 is satisfied,
When it is determined that Td = 0 is satisfied, the process proceeds to step 150 and it is determined whether or not any reception signal is received by the receiver 12. Here, when executing this step, the transmitter 1
No ultrasonic wave is output from 0, and therefore, if there is any received signal, an extraneous ultrasonic wave exists around the ground vehicle speed sensor.

Further, when such an external ultrasonic wave is present, when the transmitter 10 is operated to measure the ground vehicle speed,
The influence of the extraneous ultrasonic waves causes a situation in which the detection accuracy decreases. Therefore, in this embodiment, the above step 15 is performed.
When it is determined that there is any received signal at 0, the process proceeds to step 152, the external noise warning flag is turned on, and it is determined whether to perform a fail prevention process described later.

By the way, in order to perform such a fail prevention process, it is necessary to determine the execution period. In the present embodiment, the duration of the detected external ultrasonic wave,
Also, the generation status of the external ultrasonic waves is estimated based on the interval time at which the external ultrasonic waves are detected, and the execution continuation time of the fail prevention processing, that is, the normal return delay time is set according to the status.

That is, in step 154 following step 152, a process of decrementing the external noise duration Tx, which is the count value of the duration of the external ultrasonic wave, is performed. This Tx is a counter that is guarded below the guard value Txmax and increases its value, and becomes a larger value as the external ultrasonic wave continues for a long time.

After this processing is completed, in the following step 156, the normal return delay time to be set in the normal return timer Tf is calculated. Here, in the present embodiment, the normal recovery timer Tf has a function f (Tx) of Tx described above and a function g of a fail interval timer Ts (corresponding to an interval at which an external ultrasonic wave is detected) described later.
The sum of (Ts) is set.

As shown in FIGS. 11A and 11B, f (Tx) and g (Ts) become larger as the duration Tx becomes longer, and become smaller as the value of the fail interval timer Ts becomes larger. Is set. Therefore, the normal recovery timer Tf is set to a longer time as the occurrence state of the external ultrasonic waves is more frequent.

On the other hand, when either the braking flag or the sensor correction flag is turned on, step 158 is executed after step 140 or 142. In this step 158, it is determined whether or not the external noise warning flag is off, and only when the external noise warning flag is off, the processing from step 160 onward, that is, the ground vehicle speed detection or the sensor correction processing execution determination is executed. Processing is performed.

If it is determined in step 158 that the external noise warning flag is ON, the step of determining whether the vehicle speed detection by the ground vehicle speed sensor and the correction processing of the ground vehicle speed sensor are executed is jumped to the outside. Failure due to the influence of ultrasonic waves is prevented.

At step 160, which is executed when it is determined that the external noise warning flag is off, the transmitter 1
A command to start oscillation is issued to the oscillator 20 in order to start the operation of the transmission element of 0.

In the following step 162, an initial value K4 is set in the post-transmission delay timer Td so that an appropriate external ultrasonic wave determination can be executed later when the transmission is finished.

Upon completion of the above processing, the routine proceeds to step 164, where it is judged if the braking flag is on. This is to determine whether the execution of this step is due to the braking flag being turned on or the sensor correction flag being turned on.

If it is determined in step 164 that the braking flag is on, the process proceeds to step 166 to execute vehicle speed detection by the ground speed sensor.
The ground vehicle speed sensor ABS control execution flag is turned on. Thereby, in another routine executed to realize the ABS control, the signal output from the ground vehicle speed sensor is used as the vehicle speed signal.

On the other hand, if it is determined in step 164 that the braking flag is not on, it is determined that the execution of this step is that the sensor correction flag is on, and the routine proceeds to step 168.

Step 168 is a step for judging whether or not the above-mentioned sensor correction flag holding counter Th is "0", and only when it is judged that Th = 0 is satisfied, the routine proceeds to step 170. Then, the sensor correction control execution flag is turned on and a process for issuing a sensor correction trigger is performed. If Th = 0 is not satisfied, the process of jumping step 170 is repeated until the condition is satisfied.

When the sensor correction control flag is turned on in this manner, the sensor correction subroutine is activated, and sensitivity correction or the like is executed in accordance with the signal transfer state between the transceivers 10 and 12.

Upon completion of the above processing, step 170 shown in FIG. 6 is then executed. Here, steps 170 and 172 shown in FIG. 6 are steps executed to realize a predetermined fail prevention process when the external noise warning flag is turned on. Specifically, the external noise warning is executed in step 170. Determine whether the flag is on,
If it is on, the routine proceeds to step 172, where processing for turning on the backup control execution flag is performed.

That is, when the external noise warning flag is turned on in the present embodiment, step 166 of turning on the ground vehicle speed sensor ABS control execution flag is jumped as described above, and as a result, the output signal of the ground vehicle speed sensor outputs the vehicle speed. As a result, it becomes necessary to execute alternative control.

The backup control execution flag is a flag for displaying the necessity of executing such alternative control, and when this flag is turned on, the control does not depend on the detection signal of the ground vehicle speed sensor in another subroutine. Power control is executed.

As an alternative control executed as the fail prevention process in the present embodiment, control for stopping the ABS control and switching to normal manual braking, or an estimated vehicle speed calculated from the output signal of the wheel speed sensor, and the result thereof is calculated. A control for executing the ABS control based on the above is suitable, and a specific fail prevention process is realized by performing such a process.

After the above processing is completed, the processing after step 174 shown in FIG. 7 is executed. Step 174
Is a step of determining whether the normal recovery timer Tf set in step 156 is "0". If this time is the first processing after setting Tf, it is determined that Tf = 0 is not established, and therefore step 176 is executed next.

Step 176 is a step of decrementing Tf, and unless Tf is newly updated in step 156, the value is continuously decremented every time this routine is activated. That is, when the receiver 12 stops receiving external ultrasonic waves and it is determined in step 150 in FIG. 5 that the condition is not satisfied, Tf is decremented each time the step 176 is executed. become.

The following step 178 is a step of determining whether or not Tf = 0 holds. If Tf = 0 is not established, that is, if it is determined that the normal recovery delay time has not yet elapsed, the routine proceeds to step 180, where the fail interval timer Ts is repeatedly reset to 0 and the routine proceeds to the next step.

On the other hand, in step 174, Tf =
When 0 is satisfied, that is, when it is determined that the set predetermined normal recovery delay time has elapsed after the detection of the extraneous ultrasonic wave, the process proceeds to step 182, the extraneous noise warning flag is turned off, and for fail safe. Performs the processing to cancel the backup control that was being executed.

Then, in step 184, the external noise duration time Tx which is the basis of the calculation of the normal return delay time is calculated.
Is reset to 0 and the process proceeds to step 186. Step 1
The fail interval timer Ts 86 has an upper limit value Ts.
This is a step of determining whether or not it has reached max, and Ts
= Tsmax is satisfied, Ts = Tsm
If ax does not hold, the value is incremented in step 188 and the process proceeds to the subsequent step.

FIG. 12 shows an external noise duration Tx, an external ultrasonic wave fail interval timer Ts, and a normal recovery timer T which are realized by executing the above processing.
It is a time chart showing how the f changes.

That is, as shown in the figure, as long as the external ultrasonic wave is being received by the receiver 12 (at the time of failure), Tx increases, and as a result, Tf increases, while Ts increases. Is maintained at 0 (Fig. 12
Medium, period).

When the fail state is resolved, T
When the decrement of f is started, and Tf = 0 after the delay time for normal recovery elapses (the period in FIG. 12), the fail interval timer Ts starts increasing thereafter (FIG. 12).
Medium, period).

When the fail state is restored again, since Ts is set to a predetermined value this time, Tf becomes a relatively large value from the beginning, and thereafter the value increases with an increase in Tx (in FIG. 12, the period ), The decrement is started again with the elimination of the fail state (period in FIG. 12).

In this case, the detected value of the ground vehicle speed sensor is not used for the ABS control during the failure and before the elapse of the normal return delay time, and it is used only during the period when the external ultrasonic wave does not exist. It will be. Therefore, the vehicle speed calculated by the vehicle speed calculation circuit 30 is ABS.
When used for control, it is unlikely that the influence of an external ultrasonic wave is superimposed on the calculated value, and high control accuracy can be ensured.

In addition, when the occurrence status of the external ultrasonic wave is frequent, the normal recovery delay time is set to a long period, so that the easy recovery to the normal state is prevented, and the actual status of the external ultrasonic wave generation status. Appropriate restoration processing according to is realized. As a result, it is possible to suppress the return to the normal state under the condition where the extraneous ultrasonic waves are easily generated, and to further enhance the effectiveness of the fail prevention process.

By the way, in the above routine,
In the presence of extraneous ultrasonic waves, it is difficult to detect the vehicle speed with high accuracy due to the influence of the external ultrasonic waves.Therefore, we have decided to stop the vehicle speed detection by the ground vehicle speed sensor as a fail prevention process. For example, in such a situation, it is possible to increase the transmission power of the transmitter 10 to improve the S / N ratio and continue the vehicle speed detection in the presence of external ultrasonic waves.

FIG. 8 is a flow chart showing the contents of the processing executed to realize such a function. By executing these processings instead of step 158 described above, the influence of the external ultrasonic waves is eliminated and the ground is removed. The vehicle speed detection by the vehicle speed sensor can be continued.

That is, when the processing shown in FIG. 8 is executed as the fail prevention processing, step 140 in FIG.
The braking flag is on at step 142, or step 142
In step 190, it is determined that the sensor correction flag is on, and then step 190 (FIG. 8) is executed.

When it is determined that the external ultrasonic wave is present, the transmission power supplied to the transmitter 10 is increased to "normal time + α" in step 192, and step 194 is performed.
Then, the receiving sensitivity of the receiver 12 is set to "normal-β".
As a result, the received signal reaching the mixin circuit 26 becomes a signal having a high S / N ratio with the same intensity as in the normal state, and the external ultrasonic waves are substantially negligible.

For this reason, the vehicle speed can be detected with less influence of external ultrasonic waves by executing the processing from step 160 (FIG. 5) onward as in the above-described embodiment. Therefore, the detection value of the ground vehicle speed sensor can be detected. ABS as it is
It becomes possible to realize control.

In the present embodiment, the above step 1
40 and 142 are connected to the above-mentioned operating state switching means M3,
The above-mentioned step 150 is the above-mentioned foreign ultrasonic wave discrimination means,
Steps 158, 170, 172 and Step 19 above
0, 192, 194 correspond to the fail prevention means described above, steps 154 and 188 correspond to the external ultrasonic wave generation status detection means M6 described above, and step 156 corresponds to the return delay means M7 described above.

In the above embodiment, the ground vehicle speed sensor is illustrated as an example of the ultrasonic transmitter / receiver, but the application of the present invention is not limited to the ground vehicle speed sensor. For example, an ultrasonic transmitter / receiver is used. The present invention is also applicable to a collision detection sensor, a vehicle back sonar, and a Doppler wind velocity sensor (for example, a vehicle side wind sensor) that detects a wind velocity generated between a transmitter and a receiver by Doppler shift.

[0090]

As described above, according to the first aspect of the present invention, it is determined whether or not an external ultrasonic wave exists in the environment surrounding the ultrasonic transmitter / receiver without changing the hardware. Therefore, the accuracy of the detection result detected by using the Doppler shift in the ultrasonic transmitter / receiver can be easily and surely realized.

According to the second aspect of the present invention, the influence of the extraneous ultrasonic wave is superposed on the signal received by the receiver in the first operating state when the extraneous ultrasonic wave is present. In addition, failure due to the influence is prevented, and it is possible to maintain an appropriate state that is not affected by external ultrasonic waves.

Further, according to the third aspect of the present invention, in an environment in which the external ultrasonic waves are frequently generated, it is possible to prevent the easy return to the first operating state, so that the receiver is not affected by the external ultrasonic waves. It is possible to suppress the situation where the ultrasonic waves emitted from the transmitter are received together, that is, the situation where the influence of the external ultrasonic waves is superimposed on the reception signal of the receiver.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of an ultrasonic transceiver according to the present invention.

FIG. 2 is a block configuration diagram of a ground vehicle speed sensor which is an embodiment of an ultrasonic transceiver according to the present invention.

FIG. 3 is a flowchart (part 1) of an example of a main routine executed in the present embodiment.

FIG. 4 is a flowchart (part 2) of an example of a main routine executed in this embodiment.

FIG. 5 is a flowchart (part 3) of an example of a main routine executed in this embodiment.

FIG. 6 is a flowchart (part 4) of an example of a main routine executed in this embodiment.

FIG. 7 is a flowchart (No. 5) of an example of a main routine executed in this embodiment.

FIG. 8 is a flowchart (No. 6) of an example of a main routine executed in this embodiment.

FIG. 9 is a time chart (No. 1) for explaining the operation of the ground vehicle speed sensor of the present embodiment.

FIG. 10 is a time chart (No. 2) for explaining the operation of the ground vehicle speed sensor of the present embodiment.

FIG. 11 is an example of a map used in this embodiment.

FIG. 12 is a time chart (No. 3) for explaining the operation of the ground vehicle speed sensor of the present embodiment.

[Explanation of symbols]

 M1,10 Transmitter M2,12 Receiver M3 Operating state switching means M4 External ultrasonic wave discrimination means M5 Fail prevention means M6 External ultrasonic wave generation status detection means M7 Return delay means 18 Drive circuit 20 Oscillator 24 Preamplifier 26 Mixing circuit 30 Vehicle speed calculation Circuit 32 External ultrasonic detection circuit

Claims (3)

[Claims] 1. An ultrasonic transmitter / receiver comprising: a transmitter for transmitting ultrasonic waves to an object; and a receiver for receiving ultrasonic waves from the transmitter as a source, comprising: the transmitter and the receiver. State switching means for realizing a first operating state in which the transmitter is operated together and a second operating state in which the transmitter is stopped and only the receiver is operated, and the operating state switching means under the second operating state. An ultrasonic wave transmitter / receiver, comprising: an external ultrasonic wave discrimination means for discriminating the presence of an external ultrasonic wave based on a reception state of the receiver. 2. The ultrasonic transmitter / receiver according to claim 1, wherein when the presence of the external ultrasonic wave is determined by the external ultrasonic wave determining means, a process for preventing a failure caused by the external ultrasonic wave is performed. An ultrasonic transmitter / receiver characterized by comprising means. 3. The ultrasonic transmitter / receiver according to claim 2, wherein the occurrence state of the external ultrasonic wave is detected based on at least one of an interval time and a duration time during which the external ultrasonic wave is detected by the external ultrasonic wave discrimination means. The external ultrasonic wave generation status detecting means, and the operating state switching means based on the detection result of the external ultrasonic wave generation status detecting means from the second operating state to the first ultrasonic wave.
Ultrasonic wave transmission / reception, which is a means for determining a delay time when returning to the operating state of vessel.