JPS58154683A - Detector of obstacle - Google Patents

Abstract

PURPOSE:To remove the flicker of an obstacle even if the obstacle exists close to the border of a detection distance range, by changing a reference signal so as to increase the corresponding distance range at the detection of the existence of the obstacle, and from that time returning to the original distance range which can not detect the existence of the obstacle. CONSTITUTION:A reference pulse generating circuit 2 consists of a seven-stage binary counter 2-a, a fourteen-stage binary counter 2-b, two-gate AND circuits 2-c-2-j, an three-gate AND circuit 2-k, an inverter circuit 2-l, R/SFFs 2-m, 2-n, 2-p, 2-Q, 2-R, J-KFFs 2-s, 2-T, and OR circuits 2-U, 2-V, 2W and outputs signal to each part on the basis of a reference oscillation signal from a reference oscillation circuit. A reference signal generating means consists of R/SFFs 2-m, 2-n, 2-p, 2-Q, 2-R and AND circuits 2-k, 2-h, 2-i and a reference signal changing means consists of OR circuits 2-U, 2-V, 2-W.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an obstacle detection device that detects obstacles using ultrasonic waves.

Conventionally, in this type of device, an ultrasonic receiver receives the ultrasonic wave reflected from an obstacle by an ultrasonic pulse emitted from an ultrasonic transmitter, and generates a received pulse in a receiving circuit. and detect whether or not an obstacle exists within the obstacle detection range by comparing the received pulse with a reference signal for the obstacle detection range that is generated in accordance with the emission timing of the ultrasonic pulse. There is something like this.

However, when detecting an obstacle with such a device, if the obstacle is near the boundary bone (2) of the obstacle detection range, flickering may occur in the obstacle detection due to diffuse reflection of ultrasonic waves. There is a problem with putting it away.

The present invention has been made in view of the above problem, and when the presence of an obstacle is detected by comparing the reference signal and the received pulse, the reference signal is changed to increase its corresponding distance range, and from this point on the obstacle is detected. When the presence of an object is no longer detected, the reference signal is returned to one corresponding to the original distance range, thereby eliminating flicker for the obstacle even if the obstacle is near the boundary of the detection distance range. The object of the present invention is to provide an obstacle detection device that can perform the following tasks.

The present invention will be described below with reference to embodiments shown in the accompanying drawings.

A block diagram showing the overall configuration of an embodiment of the present invention is illustrated! In Figure 81, 1 is a reference oscillation circuit that generates a reference oscillation signal a that is the basis of all signals such as ultrasonic carrier waves and distance-specific signals, and 2 is a reference oscillation circuit 10 that uses the reference oscillation signal a as a clock input signal (3). The carrier wave pulse signals for transmission are S, C, D, and E.

Reception sensor switching signals f, g, reception waveform shaping signals ri, t
, display zone selection signals j, k, z, distance comparison reference signals m, n, p, and alarm reference signals T, i, and receive obstacle distance signals Q, R from the reception discrimination circuit 9.

Reference pulse generation circuit 3 receives transmission carrier wave pulse signals S, c, d, and e and generates hysteresis in distance comparison reference signals m, n, and p, and transmitting sensors 4-a, 4
~b (ultrasonic transmitter); 5-a and 5-b are receiving sensors as ultrasonic receivers that receive ultrasonic waves reflected from obstacles; 6 is a receiving sensor 5; -a.

A sensor switching signal f for receiving the received wave from 5-b.

7 is a receiving circuit that receives the received wave signal from the receiving switching circuit 6, performs amplification, signal selection, detection, level comparison, and generates a received pulse; 8 is a receiving circuit 7;
and the display zone selection signal j; k from the reference pulse generation circuit 2.

A gate circuit 9 receives the reception display signal from the gate circuit 8 and generates a reception display signal (4), and a gate circuit 9 receives the reception display signal from the gate circuit 8 and a reference pulse (4). A reception discrimination circuit (reception discrimination means) that discriminates the distance to an obstacle and divides the display output into obstacle zones; 10 is a display circuit that receives and displays a display signal from the reception discrimination circuit 9; 11 is a reception discrimination circuit 9; This is an alarm circuit that generates an audible warning signal in response to obstacle distance signals Q, R, and S. The display circuit 10 and the alarm circuit 11 constitute a notification means. 12 is the circuit section excluding sensors 4-a, 4-b, 5-a, and 5-b of this device; 13 is a power switch for the entire device that operates in conjunction with the reverse gear when the car is reversing; 14 15 is a fuse, and 15 is a battery installed in the automobile.

The detailed electrical connections of the reference oscillation circuit 1 are illustrated in FIG. The reference oscillation circuit 1 has a basic oscillation frequency of 640 KHz.
Ceramic resonator 1a, capacitors lb, lc,
It is composed of a register ld, inverter circuits le and if, and generates a reference oscillation signal a.

(5) The detailed electrical connections of the transmission drive circuit 3 are shown in FIG. The transmission drive circuit 3 is composed of a power supply terminal 3-1 and two sets of 5EPP drive circuits connected by transistors, and receives a transmission signal S, c or d from the reference pulse generation circuit 2.

In response to e, the transmitting sensor 4-a or 4-b emits an ultrasonic pulse.

A detailed electrical connection of the reception switching circuit 6 is shown in FIG. In this figure, 6-1 is a power supply terminal, and 6-2 is a received wave signal output terminal. Further, terminals 6-3 and 6-4 are connected to receiving sensors 5-a and 5-b, respectively. The switching signals f and g from the reference pulse generating circuit 2 cause the signal received by either the receiving sensor 5-a or 5-b to be output from the output terminal 6-2.

A detailed electrical connection of the receiving circuit 7 is shown in FIG. The receiving circuit 7 includes an amplifier 7-a and a bandpass filter? -b,
It is composed of a wave detector 7-0, a level discriminator 7-d, an R/S flip-flop circuit 7-f1, an inverter circuit 7-g, and receives a reference pulse (6), a received waveform shaping signal from the generation circuit 2, , i A reception pulse is generated by the output signal from the reception switching circuit 6 inputted at the input terminal 7-1.

A detailed electrical connection of the gate circuit 8 is shown in FIG. The gate circuit 8 is a two-gate AND circuit 8-a, 8-
Consisting of three groups b and 8-c, the received pulses input from the input terminal 8-1 according to the display zone selection signals j and n from the reference pulse generation circuit 2 are sent to the output terminal E1.
2.8-3.8-4 as a reception indication signal.

Detailed electrical connections of the reception discrimination circuit 9 and the display circuit 10 are shown in FIG. The reception discrimination circuit 9 includes D-type flip-flops 9-a to 9-4, a 3-gate NOR circuit 9-j,
9-, one of the input terminals 9-2.9-3.9-4 which is composed of 9-1 and connected to the output terminal 8-2.8-3°8-4 of the gate circuit 8. The received display signal from the reference pulse generating circuit 2 is compared with the distance comparison reference signals m, n, and p from the reference pulse generating circuit 2, and it is determined whether or not there is an obstacle within the distance corresponding to each signal m, n, and p. . Display circuit (7) 10 is an inverter circuit l0-a to 10-i, lamp 1
0 j, 10-to, 1O-It, 10-m,
10-n, 10-p, 10-Q, 10-R
, 10-8, and displays the distance to the obstacle in the three divided areas.

A detailed electrical connection of the alarm circuit 11 is shown in FIG.

The alarm circuit 11 is connected to J- by flip-flow knob 11-a, 1
1-b, 3-gate AND circuit 11-C, inverter circuit 11-e,) 5EPP circuit composed of transistors,
and a buzzer 11-d that issues an alarm, and issues an alarm in response to the obstacle distance signals Q, R, and S from the reception discrimination circuit 9. That is, the reference pulse generation circuit 2
A signal T having a frequency that makes the buzzer 11-d sound and a clock signal i are input from the
Figure 4 (11, (2), (3), (4), (5), (6)
As shown in , when Q, R, and S are all 1", the buzzer 11-
Buzzer 1 when d does not sound and Q is "0" and R and S are 1"
Make 1-d sound with duty 1/4, Q.

When R is "0" and S is "1", the buzzer 11-d is made to sound at duty 1/2, and when Q, R,'s are "O", the buzzer 11-d is made to sound continuously.

A detailed electrical connection of the reference pulse generating circuit 2 is shown in FIG. The reference pulse generation circuit 2 includes a 7-stage binary counter 2-a and a 14-stage binary counter 2-b.
, 2-gate AND circuits 2-C to 2-j, 3-gate AND circuit 2- and 1 inverter circuit 2-IR/S flip-flops 2-m, 2-n, 2-p, 2-Q
, 2-R, J- have flip-flops 2-s, 2-T
, OR circuits 2-U, 2-V, and 2-W, and generates signals to the respective circuits described above based on the reference oscillation signal a from the reference oscillation circuit 1 as shown in FIG. Sends to each circuit. In addition, R/S flip-flops 2-m, 2-n, 2-p, 2-Q, 2
-R, AND circuit 2-, 2-h and 2-i configure a reference signal generating means for generating a reference signal, and OR circuits 27U, 2-V, and 2-W change the reference signal. It constitutes a means of change.

In this embodiment, transmitting sensors 4-a and 4-b.

(9) FIG. 10 shows how the receiving sensors 5-a and 5-b are installed in a car. 16 is the rear bumper, and each sensor is as shown in the figure.
They are arranged in this order and attached to the rear bumper 16.

Note that the directional characteristics of each sensor are created by a horn (not shown) that exhibits characteristics as shown in FIG.

This directional characteristic allows the obstacle A to be detected in the overlapping part (region B) between the transmitting sensor 4-b and the receiving sensor 5-b, and the obstacle A can be detected from the transmitting sensor 4-b to the receiving sensor 5-b without passing through the obstacle. The characteristics are such that the received wave does not directly enter. Also, the transmitting sensor 4-a and the receiving sensor 5-b, and the transmitting sensor 4-a and the receiving sensor 5-a can also detect obstacles in areas C and D regardless of the direct wave as described above. It has a directional characteristic. Therefore, by having the receiving sensor 5 receive signals from the transmitting sensors 4-a and 4-b, and switching between the receiving sensors 5-a and 5-b to receive the signals sent from the transmitting sensor 4-a, Area B
, C, and D without missing a detection (10).

As shown in FIG. 11, the display 17 has a two-dimensional lamp mounted thereon, and is installed at the rear of the rear compartment seat where the driver can see and see the display 17 along with the buzzer 11-d.

Next, the operation of the above configuration will be explained.

First, a general explanation of the operation of obstacle detection will be given. Figure 12 (
11, (2), (3), and (4), T1 indicates the ultrasonic pulse of the transmitting sensor 4-b, and T2 indicates the ultrasonic pulse of the transmitting sensor 4-b.
- indicates the ultrasonic pulse of a, R1 is the receiving sensor 5-b
shows the waveform of the reflected wave from the obstacle, and R2 is the waveform of the reflected wave from the obstacle.
- shows the waveform of the reflected wave from the obstacle a. Furthermore, tl to ta in the figure indicates each time, and the time from tl to ta is the unit obstacle detection operation, that is, the transmitting sensor 4-b emits an ultrasonic pulse and the receiving sensor 5 receives the reflected wave from the obstacle. -, b, and then emit an ultrasonic pulse from the transmitting sensor 4-a, and the receiving sensor 5- receives the reflected wave from the obstacle.
b, then emit an ultrasonic pulse from the transmitting sensor 4-b, receive the reflected wave from the obstacle at the receiving sensor 5-a, and then emit the ultrasonic pulse again from the transmitting sensor 4-b. Time. After this time t8, the above operation is repeated.

In this ultrasonic transmitting/receiving operation, the time ta from the transmitting time of the transmitting sensor 4-s to the receiving time of the receiving sensor 5-b
-Detect the distance to the obstacle in area B at tl,
The distance to the obstacle in area C is detected at the time tb-t6 from the transmission time of the transmission sensor 4-a to the reception time of the reception sensor 5-b. The distance to the obstacle in the area is detected at time tc-t7 up to the time when -a is received.

Next, the entire obstacle detection operation is performed.

Now, at time t1, when the transmission signals S and C shown in FIG. 13 (1) and (2) are applied from the reference pulse generation circuit 2 to the transmission drive circuit 3, the ultrasonic wave Pulse TI is fired towards the rear of the car. Further, at time t1, the reception sensor switching signal f is inverted to "1", so that the reception sensor 5-b is in a state where reception is possible.

If a reflected wave from an obstacle behind the vehicle is received by the receiving sensor 5-b at time ta, the received wave is input from the receiving sensor 5-b to the terminal 6-4 in FIG. 4, and the receiving sensor is switched. The transistor 6-a is activated by the signal f, and the signal is increased by 11 and outputted from the terminal 6-2. Therefore, the received wave is input to the terminal 7-1 of the receiving circuit 7, passes through the amplifier 7-a and the band-pass filter 7-b to remove noise, is detected by the detector 7-c, and is detected by the level discriminator 7- d. Here, if the level of the received wave just detected is a reflected wave from an obstacle, the level discriminator? The output of -d changes from 0'' to 1. As a result, the received wave is converted into a received wave pulse and is input to the reset terminal of the flip-flop 7-f via the OR circuit 7-e.
Until the signal h from the reference pulse generation circuit 2 (Fig. 13 (
7)) resets the flip-flop 7-f,
Time 1. The signal i from the reference pulse generation circuit 2 (first
As shown in FIG. 3 (8)), the flip-flop 7-f is turned on, and its output Q becomes "1". (13) Accordingly, the output of the flip-flop 7-f changes at time 1. 1'' from time t1 to time ta when the received wave pulse is generated.As a result, the output of the receiving circuit 7 via the inverter 7-g becomes 1'' from time t1 to time t.
The signal (received pulse) is "0" up to a and then becomes "1".

This received pulse is input to the input terminal 8-1 of the gate circuit 8, and the display zone selection signal j, l (FIG. 13 (9), α, (11)) is used to select the display zone. Make a choice. Now, the received pulse "1" at time ta is output as "1" at time ta from the AND circuit f3-c of the gate circuit 8 in response to the display zone selection signal β.The received pulse "1" at time ta is used for reception discrimination. It is input to the input terminal 9-2 of the circuit 9, and the D-type flip-flop 9-g,
9-h.

This becomes the clock input signal of 9-i. The D-type flip-flops 9-g, 97L, and 9-i compare the distance comparison reference signals m, n, and p from the reference pulse generation circuit 2 using the received display signal.

The distance comparison reference signals m, n, p are shown in FIG.
) 2), (13), and (14), the respective pulse widths are made to correspond to the first, second, and third predetermined distances from the rear of the vehicle. Now, if time ta is between t3 and t4 in FIG. 13, then the D-type flip-flop 9g
, 9-h, and 9-i, the D input of 9-h and 9-i is 1 between t3 and t4, so their respective outputs are 1.
'', and the above-mentioned flip-flop 9-h
, 9-4 becomes "1", the outputs of the inverter circuits 10-h and 10-i of the display circuit 10 become the OS, and the lamps 10-R and 10-3 are turned on. Therefore, the display 17
As shown in FIG. 8, the lamp 10-3.10-R lights up to indicate that the obstacle is within the second to third predetermined distance in the right area.

In addition, in the reception discrimination circuit 9 shown in FIG. 7, since the outputs Q and R to the NOR circuits 9-j and 9- become 0'', the alarm circuit 11 changes from time t3' to t shown in FIG.
4', the buzzer 11-d intermittently sounds at duty 1/2.

On the other hand, the "0" output to the NOR circuits 9-j and 9-l-
OR circuits 2-W, 2- of the reference pulse generation circuit 2 shown in the figure
It is powered by V. Then, as the signals Q and R to the OR circuits 2-W and 2-V become 0', the outputs Q9 and Q8 of the frequency divider 2-b are output as the outputs of the OR circuits 2-W and 2-V. It is further input to the AND circuits 2-i and 2-h, and the flip-flops 2-R and 1-Q are reset by AND logic with the outputs Q12 and Q+ of the frequency divider 2-b.

These flip-flops 2-Q and 2-R are activated at time 1 by the output Q of the flip-flop 2-m. and the output R
, Q are each "1", it is reset by the output QII%Q+2 of the frequency divider 2-b, and the output of FIG. 13 (13
) and (14), but since the outputs R and Q have become "0",
The respective cents are the outputs Ql and QB of the frequency divider 2-b.
, Q10 and Q9, and as a result, the reset timing is delayed by Qe and Qq. Therefore, FIG. 13 (13),
Signal n shown in (14).

The "1" period of p becomes longer to prevent flickering for obstacle detection in each boundary area. That is, the outputs Q and R of the reception discrimination circuit 9 are fed back to the distance comparison reference signals n and p to provide hysteresis for obstacle detection, so that the time until reception varies due to slight movement of the obstacle in the boundary area, wind, etc. Even if the lamp does not flicker, it can be prevented.

Note that in the above operation, a case has been described in which the ultrasonic pulse Tl is emitted from the transmitting sensor 4-b and received by the receiving sensor 5-b, but the same applies to 4-a.

Bears 5-b, 4-a, and 5-a operate in the same manner, and the lamps on the display 17 light up to display the distance to the obstacle in the corresponding area.

In addition, in the above obstacle detection, the obstacle closest to the rear of the vehicle is detected, and the signal S from the reception discrimination circuit 9 is "0".
'', the signal S is sent to the reference pulse generating circuit 2.
(17) is input to the OR circuit 2-u at ” becomes longer.

In addition, in the above embodiment, the distance comparison reference signals m, n,
Although p has three outputs, it can be changed even if there are multiple outputs because it is determined by where the distance comparison is performed. Furthermore, although the transmitting and receiving sensors are arranged in an alternating array of four, this arrangement can also be reversed (Also, although the display shows three zones between the sensors, the detection zone can be changed depending on the number of sensors. The power switch 13 is a power switch for the entire device that operates in conjunction with the reverse gear when the vehicle is backed up, but it can be operated arbitrarily so that it does not operate in conjunction with the reverse gear. It may also be possible to detect the distance to the following vehicle or an approaching object.Furthermore, each sensor 4-a, 4-b
, 5-a, and 5-b are attached to the rear of the car, but they can also be attached to the front, side, or top, so that obstacles (18) or approaching objects can be detected from the front, side, or top. Good too.

As described above, in the present invention, a reference signal for the obstacle detection range is generated according to the emission timing of the ultrasonic pulse by the ultrasonic transmitter, and the reference signal is compared with the received pulse from the receiving circuit. In addition to determining the presence of obstacles,
When the presence of an obstacle is determined, the reference signal is changed to increase its corresponding distance range, and from this point on, when the presence of the obstacle is no longer determined, the reference signal is changed back to the original distance 111@surroundings. Therefore, even if the obstacle is near the boundary of the detection capability M@, it is possible to eliminate flickering when detecting an obstacle, and therefore obstacle notification can be performed without flickering. This has an excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a detailed electrical wiring diagram of the reference oscillation circuit in Fig. 1, and Fig. 3 is a detailed electrical wiring diagram of the transmission drive circuit in Fig. 1. , Figure 4 is a detailed electrical wiring diagram of the receiving switching circuit in Figure 81, Figure 5 is a detailed electrical wiring diagram of the receiving circuit in Figure 1, and Figure 6 is a detailed electrical wiring diagram of the gate circuit in Figure 1. Figure 7 is a detailed electrical wiring diagram of the reception discrimination circuit and display circuit in Figure 1, Figure 8 is a detailed electrical wiring diagram of the alarm circuit in Figure 1, and Figure 9 is the standard diagram in Figure 1. Detailed electrical wiring diagram of the pulse generation circuit, Fig. 10 is an installation diagram of the transmitting sensor and receiving sensor, Fig. 11 is an external view of the display, and Figs. 12, 13, and 14 are signal waveforms at each section and each path. It is a diagram. 1... Reference oscillation circuit 12... Reference pulse generation circuit. 3... Transmission drive circuit, 4-a, 4-b.
...Transmission sensor, 5-a, 5-b...Reception sensor, 6
...Reception switching circuit, 7...Reception circuit, 8...Gate circuit, 9...Reception discrimination circuit, 10...Display circuit,
11...Alarm circuit. Representative Patent Attorney Takashi Okabe Fig. 3 Fig. 1 Fig. 4 Fig. 7 Fig. 8 Fig. 1 Fig. 10 Fig. I[4 Fig. 12/T1 Fig. 14

Claims (1)

[Scope of Claims] An ultrasonic transmitter that receives carrier wave pulses of a constant frequency and emits ultrasonic pulses in a predetermined direction; an ultrasonic receiver that receives ultrasonic reflected waves reflected by an obstacle; a receiving circuit that generates a received pulse from a signal received by the ultrasonic receiver; and an ultrasonic pulse generated by the ultrasonic transmitter. a reference signal generating means for generating a reference signal corresponding to a predetermined distance range in the predetermined direction in accordance with the emission timing of the reference signal; A receiver that determines whether or not an object exists within the predetermined distance range, holds and generates an obstacle detection signal when it is determined that an object exists, and releases the generation of an obstacle detection signal when it is determined that an object does not exist. a discriminating means; a notifying means for notifying the presence of the obstacle by means of an obstacle detection signal (1) from the reception discriminating means; change to increase the range,
An obstacle detection device comprising: changing means for returning the reference signal to one corresponding to the predetermined distance range when the generation of the obstacle detection signal is canceled from this point on.