JPH03102281A - Ultrasonic wave type distance measurement device - Google Patents

Abstract

PURPOSE:To prevent wrong operation and make possible distance measurement of high reliability by setting a plurality of groups of master devices and slave devices and allowing the devices to differ in the combination of a frequencies of pulse trains of ultrasonic wave signals in each group. CONSTITUTION:Master devices and slave devices 2 are different on whether they transmit actively or not and have basically entirely same constitution. At first, the master devices transmit the combination of frequencies of inherent wave transmission pulse trains with the use of timing signals, for instance, in the order of f1 and f2. And the slave devices 2 send wave-received pulse train signals to a pulse train discrimination circuit 10 to divide them into each frequency component so as to transmit the effect that waves are received in the order of f1 and f2 into a wave receiving circuit 9. Only when the waves are received in the circuit 9 in the order of f1 and f2, the circuit 9 transmits them to a wave transmission timing setting circuit 3 so as to transmit the pulse train signals of a reply after the time of t0 and the master devices discriminating replied pulse train signals in the same manner as that of slave the devices 2. At this time, since the pulse train signals from another pairs of the master devices are, for instance, in the order of f2 and f1, wrong operation can be prevented without any transmission signal sent from the master devices 2 paired with them.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention relates to an ultrasonic distance measuring device that measures distance by transmitting and receiving ultrasonic waves consisting of a pulse train between a parent device and a slave device. be. [Prior art] This type of distance measuring device using ultrasonic waves includes one that transmits and receives ultrasonic pulses between a parent device and a slave device, and measures distance from the time required for the transmission and reception. It is known that this ultrasonic distance measuring device can measure distance relatively easily because its transmission speed is slower than distance measuring devices that use light or radio waves. One method of such an ultrasonic distance measuring device will be explained with reference to FIGS. 4 and 5. Fig. 4 g) The ultrasonic distance measuring device is used to measure the distance between vehicles A, , A2. Ultrasonic sensor 1.2
has been established. In the following description, for convenience, the ultrasonic sensor 1 of vehicle A will be referred to as a master device, and the ultrasonic sensor 2 of vehicle A2 will be referred to as a slave device. t. , Parent device 1 and child device 2
Transmission and reception during this period is performed using ultrasonic waves consisting of pulse trains. The ultrasonic wave P, consisting of a pulse train shown in FIG.
), R is delivered to slave device 2 after a delay of time t. The child device 2 waits for time t0 after delivery and then
> Send an ultrasonic wave P2 consisting of a pulse train as shown in
As shown in the same figure (d), after a delay of time t2, the R
2 is received. Master unit 1 has wave transmission waiting time t0 of slave unit 2.
is given in advance, the distance d between the parent device 1 and child device 2 is expressed by the following formula. d=(t-t,)÷2Xc or d=(t++tz)÷2Xc where C is the speed of sound. The method for determining these distances lllid is described in Japanese Patent Application No. 62-260034 and Japanese Patent Application No. 63-
48119, Japanese Patent Application No. 63-48120, etc. [Problem to be Solved by the Invention 1] However, in order to provide a high degree of reliability, when using multiple ultrasonic distance measuring devices, each device measures distance, and the results of multiple distance information are used. There is. In such a case, it would be good if all the ultrasonic distance measuring devices were synchronously wired so that they could transmit waves at the same time, but if they were to operate independently, they could malfunction due to transmission pulses other than their own. There were problems with the distance data being significantly different from the actual distance, and distance measurement being impossible. The present invention has been provided in view of the above-mentioned points, and an object of the present invention is to provide a parent-child type ultrasonic distance measuring device that does not malfunction even when a plurality of devices are operated independently. ．． [Means for Solving the Problems] The present invention includes a parent device that transmits an ultrasonic signal consisting of a pulse train of a combination of a plurality of frequencies, and a parent device that receives the ultrasonic signal from the parent device, and A plurality of sets are provided, each consisting of a child device that returns an ultrasonic signal consisting of a pulse train to the parent device after a predetermined period of time has elapsed, and the ultrasonic signal is returned from the child device from the time of transmission of the ultrasonic signal from the parent device. The parent device is equipped with at least a distance measuring means for measuring the distance between the parent device and the child device based on the time required for the parent device to receive an ultrasonic signal, and the ultrasonic device used by one set of the parent device and the child device is provided. The sound wave signal is characterized by having different combinations of pulse train frequencies for each set. [Function] Therefore, the ultrasonic signals used by one set of the parent device and the slave device are made to have different combinations of pulse train frequencies for each group, and the distance measuring means is used to detect multiple ultrasonic signals from the parent device. The distance between the parent device and the child device is measured by the time required from the point of transmission of an ultrasonic signal consisting of a pulse train of a combination of frequencies until the parent device receives the ultrasonic signal returned from the child device. I have to. [Example 1] Hereinafter, an example of the present invention will be described with reference to the drawings. The present invention transmits an ultrasonic wave consisting of a transmission pulse train of a combination of a plurality of frequencies from a master unit 1, receives the ultrasonic wave at a slave unit 2, and after a preset predetermined time has elapsed. , the slave unit 2 returns an ultrasonic wave consisting of a pulse train to the master unit 1, and the period from the time of transmission of the ultrasound from the master unit 1 to the time when the master unit 1 receives the ultrasonic wave returned from the slave unit 2. The distance between the master device 1 and the slave device 2 is measured based on the time required.
This system operates multiple ultrasonic distance measuring devices as shown in Figure 1 independently. In addition, in the following example, 2
We will discuss three ultrasonic distance measuring devices, but three or more devices can be considered in exactly the same way. Therefore, a pair of ultrasonic distance measuring devices consisting of a parent device 1 and a slave device 2 that measure distance by transmitting and receiving a transmission pulse train of a certain frequency combination, and a transmission pulse train of a different frequency combination are used. Let's consider another pair of ultrasonic distance measuring devices: a master device 1 that measures distance by transmitting and receiving waves in a row, and a slave device 2. In FIG. 1 showing a block diagram, a wave transmission timing setting circuit 3 is a circuit that outputs the timing to start wave transmission. The pulse train control circuit 4 determines the frequency combination of the pulse train to be transmitted, and the wave transmission circuit 5 is a circuit that controls the ultrasonic pulse signal of the tone burst wave having a preset duration. The wave transmission drive circuit 6 is a circuit that amplifies the ultrasonic pulse signal obtained by the wave transmission circuit 5 so that it can sufficiently drive the ultrasonic transducer 7. In this embodiment, the ultrasonic transducer 7 is of an integrated type for transmitting and receiving, but there is no problem in using two ultrasonic transducers, one for transmitting and receiving and the other for delivery. The delivery gate circuit 8 is a circuit that sets the time to start and end time to capture the received signal after transmitting the ultrasonic pulse. The pulse train discrimination circuit 10 obtains information on the combination of frequencies of the transmitted pulse train determined by the pulse train generation circuit 4, and outputs which frequency component of the pulse was received and the order thereof to the delivery circuit 9. This is the circuit. The delivery circuit 9 is a circuit that amplifies the received ultrasonic pulse, and obtains a signal from which a distance calculation section 91 provided inside the delivery circuit 9 can calculate the distance. Distance calculation unit 9
1 is a part that calculates the distance between the parent device 1 and the child device 2. Note that the distance calculation section 91 uses an ellipse as a distance measuring means. The present invention transmits an ultrasonic wave consisting of a pulse train of a plurality of frequency combinations from a master unit, receives the ultrasonic wave at a slave unit, and after a preset period of time has elapsed, the ultrasound wave is transmitted from the master unit to the slave unit. The distance between the parent device and the child device is determined by the time required from the time the parent device transmits the ultrasonic wave to the time the parent device receives the ultrasonic wave returned from the child device. When multiple ultrasonic distance measuring devices are operated independently to measure distance, each pulse train has a different combination of frequencies, so that it does not measure distance using pulse trains other than its own. The operation will be explained in detail below. 2 and 3 are time charts of an embodiment of the present invention. It should be noted that the basic ellipsoidal structure of parent device 1 and slave device 2 is exactly the same, with the only difference being whether or not they themselves actively transmit waves. In the base device 1, when the timing signal for starting wave transmission is output from the wave transmission timing setting circuit 3, the pulse train generation circuit 4 receives this and determines the combination of frequencies of the transmission pulse train (this is the frequency combination of each wave pulse train). It is device-specific, for example, the order of frequencies rl.f2, or fz, f+
t')jli[, etc. ), based on which, the transmitting circuit 5 generates an ultrasonic pulse train signal of a tone burst wave with a preset duration. In this example,
f. = 40kHz, f2 = 32kHz, but
It is not limited to this. This is amplified by the wave transmission drive circuit 6, and the second
As shown in Figure (a), waves are transmitted from the ultrasonic transducer 76. Furthermore, since the waves are transmitted and received over several frequency bands, the characteristics of the ultrasonic transducer 7 are wide band or multiple detection frequency bands. We need something with . It can also be realized by using multiple ultrasonic transducers for transmitting and receiving waves with different detection frequency bands, or by using separate ultrasonic transducers for transmitting and receiving waves.
The slave device 2 receives the ultrasonic pulse train signal from the parent device 1 as shown in FIG. Ru. The pulse train discrimination circuit 10 is composed of a plurality of band-pass filters that can separately discriminate the frequency f and frequency f2 components. When the ultrasonic pulse train signals enter in the order of f+ and fz, the pulse train discrimination circuit 10
is divided into each frequency component, and after the f component is delivered, the f2 precept is delivered, and this fact is sent to the delivery circuit 9.

Since the pair of parent unit 1 and slave unit 2 have the same frequency combination of transmitting pulse trains, the receiving circuit 9 has f,
, f. It is only when the waves are received in the order of t that the ultrasonic pulse train signal is sent back to the main unit 1. A signal is sent to the transmission timing setting circuit 3 to transmit the wave after a certain period of time. The ultrasonic pulse train returned from slave device 2 (Fig. 2(b)) is in the order of f+, f2, as in parent device 1, so parent device 1 receives the returned ultrasonic pulse train from slave device 2. The ultrasonic pulse train signal from another pair of parent devices is determined in the same way as the child device 2 (Fig. 2 (a)).
), the order of f2, f, is reverse to that of the previous one, so in the pair of slave units 2 described above, the ultrasonic pulse train signals are in the order of f2, f. Even if the ultrasonic pulse train signals arrive in the order of f2, f, the pulse train discrimination circuit 10 determines that the ultrasonic pulse train signals come in the order of f2, f, and sends this to the delivery circuit 9. In the delivery circuit 9, since it is not the order of f and f2, the ultrasonic pulse train signal to be returned to the master device 1 is not transmitted (FIG. 3(b)).
With the above functions, it is possible to exchange ultrasonic pulse train signals between the paired parent unit 1 and slave unit 2, but the ultrasonic pulse train signals can be exchanged between the unpaired parent unit and slave units. You can prevent it from responding even if a signal is received. [Effects of the Invention] As described above, the present invention includes a parent device that transmits an ultrasonic signal consisting of a pulse train of a combination of a plurality of frequencies, and a device that receives the ultrasonic signal from the parent device and receives a preset signal. A plurality of sets are provided, each consisting of a child device that returns an ultrasonic signal consisting of a pulse train to the parent device after a predetermined period of time has elapsed, and the ultrasonic signal is returned from the child device from the time of transmission of the ultrasonic signal from the parent device. The parent device is equipped with at least a distance measuring means for measuring the distance between the parent device and the child device based on the time required for the parent device to receive an ultrasonic signal, and the ultrasonic device used by one set of the parent device and the child device is provided. Since the sonic signal has a different combination of pulse train frequencies for each set, the ultrasonic signal used by one set of the parent device and slave device is made by changing the combination of pulse train frequencies for each set. The time required from the time when an ultrasonic signal consisting of a pulse train of a combination of multiple frequencies is transmitted from the parent device until the parent device receives the ultrasonic signal returned from the slave device using a distance measuring means. By measuring the distance between the parent device and child device, even if multiple sets of parent device and child device are operated independently, ultrasonic waves will only be generated between the paired parent device and child device. This has the effect of providing a parent-child type ultrasonic distance measuring device in which pulse train signals can be exchanged, and each device does not malfunction.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a time chart of the same as above, FIG. 3 is a time chart of the same as above, and FIG.
The figure is an explanatory diagram of the operation of the conventional example, and Fig. 5 is a time chart of the same. 1 is the parent device, and 2 is the child device.

Claims (1)

[Claims] (1) A parent device that transmits an ultrasonic signal consisting of a pulse train of a combination of multiple frequencies, and after receiving the ultrasonic signal from the parent device and elapsed for a preset period of time,
A plurality of sets are provided, each consisting of a child device that returns an ultrasonic signal consisting of a pulse train to the parent device, and the parent device receives the ultrasonic signal returned from the child device from the time of transmission of the ultrasonic signal from the parent device. At least the parent device is equipped with a distance measuring means for measuring the distance between the parent device and the slave device based on the time required to receive the wave, and the ultrasonic signals used by one pair of the parent device and the slave device are transmitted to each pair. An ultrasonic distance measuring device characterized by having different combinations of pulse train frequencies.