JPH01312489A - Ultrasonic wave distance measuring apparatus - Google Patents

Abstract

PURPOSE:To prevent erroneous operations due to reflected waves from distant walls and obstacles by commonly using an amplifier circuit and a timer and providing masking means in a device wherein pulses are outputted to a plurality of output terminals and ultrasonic waves are sent out in each measuring direction. CONSTITUTION:Ultrasonic waves are transmitted in each direction from ultrasonic wave piezoelectric transducers 6a-6c which are sequentially driven with oscillating circuits 3a-3c. The reflected waves are received with the ultrasonic wave piezoelectric transducers 6a-6c and inputted into a single amplifier circuit 9 through masking means 12a-12c. Passing of unnecessary reflected waves is inhibited with the masking means 12a-12c. Therefore, the unnecessary reflected waves are not inputted into the amplifier circuit 9. The time from the start of the transmission to the generation of the reflected wave in the amplifier circuit is measured with a timer means 8. The time is converted into the distance datum. When the natural frequencies of the oscillating circuits 3a-3c and the ultrasonic wave piezoelectric transducers 6a-6c are made different, only the reflected waves of the transmitted signals of the apparatus itself become the received outputs. Erroneous operations due to transmitted signal which are oscillated in other ultrasonic wave piezoelectric transducers are not detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic distance measuring device used in automatic guided vehicles, mobile robots, and the like.

2. Description of the Related Art In automatic guided vehicles and mobile robots, a plurality of sensors are often used to limit or stop movement by recognizing the position of walls or obstacles in the external environment. This is because the sensor only has a limited detection range, so it can more accurately recognize the external environment. We measure the distance using ultrasonic waves and find out the distance between the external environment and the mobile robot body.
It is possible to control the movement of the mobile robot body, for example to move it along a wall, but even in this case, at least two ultrasonic sensors, one on the side and one in front, are required. Many sonic distance measuring devices are configured as shown in FIG. When the pulse generating means 2, which is an internal function of the microcomputer 1, outputs a positive pulse to the output terminal a, the oscillation output of the oscillation circuit 3 becomes ANDN-.
The driver 5a passes through the entire gate for a time equal to the width of the pulse.
The ultrasonic wave 7a is applied to the ultrasonic transducer 6a via the ultrasonic wave 7a, and is sent into the air. At the same time, the output of the pulse generating means 2 starts the operation of the timer 8a. When the reflected wave of the ultrasonic wave 7a returns and is received by the ultrasonic transducer 6a, this minute output is amplified by the amplifier circuit 9a, and the operation of the timer 8a is stopped. The distance to a reflecting object (not shown) can be calculated as a time value by the relationship shown in the following equation, and this value is read by the microcomputer 1.

1 = - (1: time, V: sound speed, l: distance order) In the case of a configuration using multiple sensors, multiple sets of the above circuit configurations will be provided, and in the case of Fig. 5, pulse generation outputs a, b
, c, and is made up of three sets, making it a distance measuring device that can measure distances in three directions.

Problems to be Solved by the Invention This conventional configuration allows simultaneous measurement in three directions and has the advantage of short measurement time. There is a problem in that timers 8a, 8b, 8c are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic distance measuring device that can accurately measure distances in a plurality of directions in a short time and can also reduce the number of amplifier circuits and timers.

Means for Solving the Problems The ultrasonic distance measuring device according to claim 1 comprises pulse generating means for outputting pulses to a plurality of output terminals at fixed time intervals, and ultrasonic waves for transmitting ultrasonic waves in each measurement direction. a plurality of ultrasonic transducers installed in the ultrasonic transducer; a gate circuit that sequentially supplies ultrasonic waves generated by a single oscillation circuit to each ultrasonic transducer by the pulses of the pulse generating means; a plurality of mask means for allowing the reflected wave reception output of the acoustic wave transducer to pass only within the predetermined time period in synchronization with the pulse of the pulse generation means; and a single amplifier to which each output of the mask means is connected to the input side. a circuit, a timer means that starts operation at the output timing of the pulse of the pulse generating means, detects the received output of the eight output side of the amplifier circuit, and stops the operation; The ultrasonic distance measuring device according to claim 2 is characterized in that the ultrasonic distance measuring device calculates the distance to a reflecting object in the measurement direction. A plurality of ultrasonic transducers installed to transmit sound waves, a plurality of oscillation circuits that supply ultrasonic signals to each ultrasonic transducer by the pulses of the pulse generating means, and masking means for each ultrasonic frequency. and a single amplifier circuit in which each blade of the mask means is connected to the input side, and the operation is started at the timing of the output of the pulse of the pulse generating means to determine the reception output side of the output side of the amplifier circuit. For those equipped with a timer means that detects and stops, and the angle between the measurement directions is small, the natural frequency of one oscillation circuit and ultrasonic transducer is different from the other natural frequency, and the timer means According to the structure of special effect claim 1, characterized in that the distance to the reflecting object in each measurement direction is calculated from each time value, ultrasonic waves are generated from each ultrasonic transducer in each measurement direction by being sequentially driven by an oscillation circuit. is sent. The reflected waves are received by the ultrasonic transducer and input into a single amplifier circuit via mask means. The unnecessary reflected waves are prohibited from passing through by the mask means and are not input to the amplifier circuit.

The time from the start of transmission until the reflection 511 occurs in the amplifier circuit is measured by a timer 1 and converted into distance data.

According to the structure of claim 2, since there are a plurality of oscillation circuits and the natural frequencies of the oscillation circuit and the ultrasonic transducer are made different, even if an ultrasonic wave from another ultrasonic transducer wraps around, a reception output is generated. Instead, only the reflected wave of the own transmitting signal becomes the received output, and the transmitting signal emitted from another ultrasonic transducer does not accidentally pass through the own masking means.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an explanatory view of an embodiment of claim 1, and FIG. 2 shows a comparative example for comparing characteristics with the device of the present invention.

First, the comparative example shown in FIG. 2 will be explained. Output terminal a of pulse generating means 2, which is an internal function of microcomputer l
, b, c are AND game with the output of the oscillation circuit 3) 4a
, 4b, and 4c, and the outputs of the AND gates 4a, 4b, and 4c are input to ultrasonic drive drivers 5a, 5b, and 5c, and these outputs are transmitted to ultrasonic transducers 6a and 6a having the same natural frequency.
6t) and 6C. Ultrasonic transducer 6a
, 6b, 6c also include clippers 13a, 13 using diodes or the like as circuits for receiving reflected waves.
b and 13C are connected, and their respective outputs are connected to one line and inputted to an amplifier circuit 9, and the output of the amplifier circuit 9 is inputted to a timer means 8, which is an internal function of the microcomputer l. As for the operation of this comparative example, when the pulse generating means 2 outputs a pulse to the output terminal a, the timer means 8 starts operating at the same time. When a pulse is output to the output terminal, child a, the oscillation frequency of the ultrasonic wave generated by the oscillation circuit 3 is transmitted by the gate 4a of M to the driver 5a for the time of the above-mentioned pulse interval.
to drive the ultrasonic transducer 6a and send out ultrasonic waves into the air. At this time, the voltage of the other ultrasonic transducers 6b, 6C is suppressed by the clippers 13a, 13b, 13c and they are not driven. When the reflected wave of the transmitted ultrasonic wave returns to the ultrasonic transducer 6a and is received, the received voltage is extremely small, so it passes through the clipper 13a, is transmitted to the amplifier circuit 9, is amplified, and is input to the timer means 8 as a signal d. hand,
The operation of the timer means 8 is stopped. Depending on the value of this timer means 8, the ultrasonic transducer 6? and the distance to the reflecting object can be measured.

By sequentially switching between the output terminals a and c, distance measurement in three directions, that is, three distances, can be performed with one amplifier circuit 9 and one timer means 8.

Although this comparative example has some problems, a comparative explanation will be given after the explanation of FIG. 1.

In FIG. 1, output terminals a and b of a pulse generating means 2, which is an internal function of a microcomputer 1.

C are connected to oscillation circuits 3a, 3b, 3c and mask time generating means 10a, 10b, 10c, respectively. The outputs of the oscillation circuits 3a, 3b, 3c are connected to ultrasonic transducers 6a, 6b, 6c via drivers 5a, 5b, 5c, respectively. Analog switch lla as a circuit that receives reflected waves
, llb, llc are ultrasonic transducers 6a, 6
b and 6C, and the other one is connected to one line and input to the amplifier circuit 9, and the output is connected to timer means 8, which is an internal function of the microcomputer 1. Mask time generating means 10a, 10b, 10c
The output of the analog switch 111, llb
, llc, and the combination of these two mask means 12a, 12.
b.

12c. As for the operation of this embodiment, when the pulse generating means 2 outputs a pulse to the output terminal a, the timer means 8 starts operating at the same time. The oscillation circuit 3a operates for a time corresponding to the pulse interval of the output terminal a, and drives the driver 5ae to drive the ultrasonic transducer 6a and send out ultrasonic waves into the air. After the ultrasonic transducer 6a is driven, the analog switch lla is turned on by the mask time generating means lOa. When the reflected wave of the transmitted ultrasonic wave returns to the ultrasonic transducer 6a and is received, the received pressure is transmitted to the amplifier circuit 9 through the analog switch lla, where it is amplified and input to the timer means 8 as a signal e. The operation of the timer means 8 is then stopped.

When the mask time generating means 10a elapses, the analog switch lla is turned off, and the reflected waves returning to the ultrasonic transducer 6a are not detected thereafter. Similarly, by sequentially switching output terminals a and c, three distance measurements can be performed with one amplifier circuit 9 and one timer means 8.

Hereinafter, the operation of measuring a distance by applying this embodiment to a mobile robot and its distance measurement waveform will be explained using FIGS. 3 and 5. At this time, the distance measurement waveform of the comparative example will also be explained to clarify the problem and further clarify the characteristics of the present example.

FIG. 3 shows the mobile robot 15 moving along the left wall 14. Here, the ultrasonic transducer 6a shown in FIGS. 1 and 2,
6b and cic are arranged for left distance measurement (6a), front distance measurement (6b), and right diagonal front (6c), respectively. The ultrasonic waves sent out by the ultrasonic transducer 6a are also received by the ultrasonic transducer 6a after a time 1/ corresponding to the distance 11. Similarly, for the ultrasonic transducer 6b, the distance! 1 and will be received after time itt. In this case, the ultrasonic waves emitted from the ultrasonic transducer 6c are reflected by the left wall 14 and then reflected by the front wall 16, resulting in a positional relationship in which the reflected waves do not return to the original ultrasonic transducer 6c. There is.

Based on the above settings, the timing of transmission and reception and the received waveform will be explained with reference to FIG.

Output terminal a of the pulse generating means 2 in FIGS. 1 and 2
, b, and c are shown as AI, Bl, and CI in FIG. 5, and are moved at time intervals of to in order to drive and measure sequentially as described above. When a pulse is output from output terminal a, the time meter is 111! I is performed by the timer means 8, and this operation is continued until the output terminal outputs the next pulse. If the reflected wave returns during this time, the distance to the wall is measured from that time, and if the reflected wave does not return, it is assumed that there is no wall.The same applies to the output terminals S and C.

When measured with the distance measuring device according to the comparative example of FIG. 2 in the positional relationship shown in FIG. 3, the signal d received by the timer means 8 has a waveform shown by d in FIG. 5. In other words, when a pulse is emitted at output terminal a, the reflected wave is received as Ea and T
/ is measured. When the output terminal outputs a pulse, since the front wall 16 is far away, it is received as Eb with a delay. In this case, it is originally 1/.

should be measured, but since the pulse has been emitted at the output terminal C as described above, the incorrect value 1/ is measured.

When the same positional relationship shown in FIG. 3 is measured using the distance measuring device shown in FIG. 1, mask time generating means 10a #10b in FIG.
The output of the ultrasonic transducer 6a has the waveform shown by A2, B2, and C2 in FIG. 5, and the received output of the ultrasonic transducer 6a is A
The signal can only pass through the analog switch lla for a period of 2 tl. The same applies to the other two ultrasonic transducers 6b and 6(:).Therefore, the received signal e to the timer means 8
has a waveform shown by El in FIG. 5, which prevents erroneous measurements due to reflected waves from distant walls.

Although the configuration shown in FIG. 1 uses the oscillation circuits 3a to 3C, the same applies even if the configuration includes a single oscillation circuit and a gate circuit. The single oscillation circuit and gate circuit mentioned here are the oscillation circuit 3 and AN shown in FIG.
These are D gates 4a to 4c.

An embodiment of claim 2 will be explained based on FIGS. 1, 4, and 5. In the configuration of claim 1, the oscillation circuits 3a to 3c
The oscillation frequencies of the ultrasonic transducers 6a to 6c were the same, and the natural frequencies of the ultrasonic transducers 6a to 6c were the same.
Errors occur in the situation shown in the figure.

In FIG. 4, the mobile robot 15 with the same arrangement of ultrasonic transducers 6a, 6b, and 6c as in FIG. 3 is moving along the left wall 14, but the angles of the left wall 14 and the front wall 16 are different. Therefore, the reflected state of the ultrasonic waves is different from that in FIG. In the arrangement shown in this figure, the distance measured by the ultrasonic transducer 6a is the distance tlzt, which does not change 171 in terms of time, but the ultrasonic transducers 6t) and 6c receive the ultrasonic waves sent by each other as reflected waves. The positional relationship is as follows, and the distance is! 4 conversion time is tl4. In the positional relationship shown in FIG. 4, the natural frequencies of the ultrasonic transducers 6a, 6b, and 6c are almost the same, that is, the oscillation circuits 3a and 3b.

When the oscillation frequencies of 3c are the same, the reception output e has a waveform shown by B2 in FIG. The reflected wave for pulse 7, 1C of output terminal a is Ea, and the time conversion is j/l. The wave hits the wall twice before being received by the ultrasonic transducer 6C, so the waveform El) is measured. Ru. Originally, j/4 should be measured, but since the pulse has been emitted at the output terminal C as described above, an incorrect value Els is measured. Similarly, the reflected wave from the output terminal C's bulb reaches the ultrasonic transducer 6b after a time tl, but in this case, as can be seen from the waveform of B2, the analog switch llb is in the OFF state. Therefore, it will not be measured. One caution in this measurement is that the reflected wave of the ultrasound transmitted by the ultrasound transducer 6b is not transmitted to the other ultrasound transducer 6.
c occurs for receiving, and for this reason, the first
In the illustrated embodiment, oscillation circuits 3a, 3b, 3c (P
Since they are provided independently, they can be eliminated by changing the oscillation frequency of each ultrasonic transducer 6a, 6b, and 6c little by little as a set, and the waveform of B2 can be set to El. Furthermore, in reality, as is clear from the embodiments, it is not necessary to change the oscillation frequencies of all the ultrasonic transducers, and those having an angle of 90° or more may have the same frequency. In Claim 2, the phrase "the angle formed by the measurement direction is small" means an angle smaller than 90 degrees.

In each of the above embodiments, the masking means 12a to 12c are provided separately from the microcomputer 1, but they can also be incorporated into the microcomputer 1.

Effects of the Invention As described above, according to the structure of each claim, the amplifier circuit and the timer are shared and the masking means is provided to prevent reflected waves from distant walls or obstacles from causing malfunction. distance measurement. When applied to mobile robots, etc., it is necessary to perform multiple distance measurements in a relatively short period of time, which causes the problems mentioned above. At the same time, current one-chip microcomputers do not have timers (built-in counters). However, considering that the number of timers is small, it goes without saying that the present invention is highly effective in simplifying ultrasonic distance measuring devices.

According to the structure of claim 2, for those in which a plurality of oscillation circuits are provided and the angle between the measurement directions is small,
Since the natural frequencies of one oscillation circuit and ultrasonic transducer are different from those of the other, it is possible to avoid situations where other ultrasonic transducers receive the signal due to wraparound, allowing for more accurate distance measurement. It can be done.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of claim 1 and this embodiment, FIG. 2 is a circuit block diagram showing a comparative example, FIGS. 3 and 4 are plan layout diagrams when applied to a mobile robot, and FIG. FIG. 6 is a timing diagram of distance measurement waveforms, and is a circuit block diagram showing a conventional ultrasonic distance measurement device. 2... Pulse generating means, 3.3a, 3b, 3
c...Oscillation circuit, 4a to 4c-AND gate, 6a, 6t), 6c--ultrasonic transducer, 8-
...Timer means, 9...Amplification circuit, 12a. 12b, 12c... mask means. /, Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A pulse generating means that outputs pulses to a plurality of output terminals at fixed time intervals, a plurality of ultrasonic transducers installed to transmit ultrasonic waves in each measurement direction, and a single a gate circuit that sequentially supplies the ultrasonic signal generated by the oscillation circuit to each ultrasonic transducer by the pulse of the pulse generating means; a plurality of masking means that synchronize with the pulse and allow it to pass only within the predetermined time; a single amplifier circuit to which each output of the masking means is connected to the input side; and a pulse generation means that operates at the timing of output of the pulse. and a timer means for starting and stopping after detecting the received output on the output side of the amplifier circuit, and calculating the distance to the reflecting object in each measurement direction from each time value of the timer means. 2. A pulse generating means that outputs pulses at regular intervals to a plurality of output terminals, a plurality of ultrasonic transducers installed to send out ultrasonic waves in each measurement direction, and a a plurality of oscillation circuits that supply ultrasonic signals to each ultrasonic transducer, and a plurality of masks that allow the reflected wave reception output of each ultrasonic transducer to pass only within the certain period of time in synchronization with the pulse of the pulse generating means. means and a single amplifier circuit with each output of the masking means connected to the input side;
and a timer means that starts its operation at the timing of the output of the pulse of the pulse generating means and stops after detecting the received output on the output side of the amplifier circuit, and the angle between the measuring directions is small, An ultrasonic distance measuring device in which the natural frequencies of one oscillation circuit and ultrasonic transducer are made different from those of the other, and the distance to a reflecting object in each measurement direction is calculated from each time value of a timer means.