JP2003270345A - Obstacle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speed up response in transfer to an obstacle detecting operation in an obstacle detector based on ultrasonic waves. <P>SOLUTION: An ultrasonic sensor 30 previously monitors noise before receiving an ultrasonic wave transmission instruction from a control ECU 20, and on receiving the ultrasonic wave transmission instruction, returns noise detection information to the control ECU with distance information. If the noise detection information shows absence of noise, the ECU makes the distance information valid. If the noise detection information shows existence of noise, the control ECU makes the distance information invalid and makes the previous distance information valid. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an obstacle detection device for transmitting an ultrasonic wave and detecting the obstacle based on the ultrasonic wave reflected by the obstacle.

[0002]

2. Description of the Related Art Generally, in order to detect an obstacle such as a front and rear of a vehicle, an obstacle detecting device of this type has a vehicle shift position of R, D, 2, L and a vehicle speed of For example, in the case of 10 km / h or less, ultrasonic waves are transmitted from a microphone as a transducer having a transmission / reception function, and ultrasonic waves reflected by an obstacle are received by the microphone, from the time of transmitting ultrasonic waves to the time of receiving reflected waves. The distance to the obstacle is detected based on the time.

Further, in detecting this distance, ultrasonic waves are received without transmitting ultrasonic waves for a certain period before ultrasonic waves are transmitted, and noise monitoring is performed to confirm whether or not there is ultrasonic noise. ing. The reason for this is that the distance to the obstacle cannot be accurately detected when there is an ultrasonic wave other than the ultrasonic wave transmitted from the microphone, for example, an ultrasonic wave contained in a horn, so that the surroundings of the vehicle are stable. Check that the obstacle can be detected. If it is determined by noise monitoring that there is no noise, an alarm is issued based on the distance to the obstacle detected by the next obstacle detection processing (ultrasonic wave transmission, reflected wave reception), while When it is determined that there is noise, the distance to the obstacle detected by the next obstacle detection process is ignored and the distance detected and held by the previous obstacle detection process is used. To issue an alarm.

By the way, as a configuration of this device, when the vehicle is in the shift position R, D, 2, or L and the vehicle speed is, for example, 10 km / h or less, it is installed in the front and rear bumpers of the vehicle. The control ECU (electronic control unit) transmits an ultrasonic signal (analog signal) to the generated ultrasonic sensor, and the ultrasonic sensor transmits this ultrasonic wave to the surroundings of the vehicle and the ultrasonic wave reflected by the obstacle is detected. There is known an analog configuration in which the control ECU receives the signal and transmits it to the control ECU, and the control ECU detects the distance to the obstacle based on the time from the transmission of the ultrasonic wave to the reception of the reflected wave.

However, in the above analog configuration, since only the control ECU has the arithmetic function, various problems occur. For example, a signal sent from each ultrasonic sensor to the control ECU is a weak analog signal of about several mV, and there is a problem that noise resistance is low. That is, since this weak analog signal is transmitted from the front and rear bumpers to the control ECU for a long distance, there is a problem that various electromagnetic wave noises superimposed in the process are erroneously recognized as an obstacle detection signal.

Therefore, as a method for solving this problem, the sensor is provided with a calculation function, and the vehicle shift position is one of R, D, 2, and L and the vehicle speed is, for example, 10 km / h or less. In this case, the control ECU transmits an ultrasonic wave transmission command (digital signal) to the sensor, and the sensor transmits the ultrasonic wave to the surroundings of the vehicle to detect the ultrasonic wave reflected by the obstacle. The distance to the obstacle is detected based on the time from the reception of the ultrasonic wave to the reception of the reflected wave, and this distance information is transmitted to the control ECU. The control ECU receives the distance information received from the sensor. A digital configuration is possible in which an alarm is issued based on the above.

[0007]

However, in the digital configuration in which the sensor has the arithmetic function as described above, the vehicle shift position is either R, D, 2, or L and the vehicle speed is, for example, 10 km / h. Control ECU in the following cases
Transmits an ultrasonic wave transmission command, the sensor receives the ultrasonic wave transmission command from the control ECU, and when the actual obstacle detection operation is performed after performing the above noise monitoring, the obstacle detection operation is performed. There is a problem that the response is delayed due to delay.

In view of the above problems, it is an object of the present invention to provide an obstacle detecting device capable of speeding up the response when shifting to the obstacle detecting operation.

[0009]

In order to achieve the above object, the present invention is such that a sensor monitors noise in advance before receiving an ultrasonic wave transmission instruction from a control unit. With the above configuration, when the sensor receives an ultrasonic wave transmission instruction from the control unit, it is possible to immediately shift to the obstacle detection processing without monitoring noise, so that the response can be speeded up.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> An embodiment of the present invention will be described below with reference to the drawings. Figure 1
2 is a block diagram showing a first embodiment of an obstacle detection device according to the present invention, and FIG. 2 is a flow chart for explaining processing of the sensor of FIG.

In FIG. 1, an ultrasonic sensor 30 (30-1, 30-2, 30-3, 30-4) having a calculation function is installed at an appropriate obstacle detection position such as a bumper in front of and behind the vehicle, and the bus 25 It is connected to the control ECU 20 via. The microcomputer 21 in the control ECU 20 includes the ID of each sensor 30 and the ultrasonic transmission command when the vehicle shift position is any of R, D, 2, and L and the vehicle speed is, for example, 10 km / h or less. Send a polling frame.

First, when the power source (the vehicle ignition switch) is turned on, the microcomputer 21 sends a command for initializing the sensor 30 to the communication driver / receiver (D).
/ R) 22 and outputs to the bus 25. Sensor 30
Then, as shown in FIG. 2, when the LAN control circuit 32 receives this initialization command through the communication D / R 31, the operation shifts to a noise monitoring operation (steps S1 → S2). In the noise monitoring in step S2, ultrasonic noise reception processing is performed without transmitting ultrasonic waves by the microphone 34 as a transducer having a transmission / reception function. The gain of the ultrasonic noise signal is adjusted by the gain adjusting circuit 37 and then applied to the comparator 38.

In the comparator 38, the output of the gain adjusting circuit 37 is compared with the value adjusted by the threshold adjusting circuit 36 for the noise judgment threshold value output from the LAN control circuit 32. Here, the gain adjusting circuit 37 and the threshold adjusting circuit 36 adjust each input signal to the gain and the adjustment value stored in the non-volatile memory 39 or the LAN control circuit 32 in advance. Then, when the ultrasonic noise signal> the threshold value for noise judgment by the comparator 38, the LAN
The control circuit 32 stores “with noise” as the noise detection information, and then waits for a polling frame of a transmission command including the self ID from the control ECU 20 (step S
3) The noise monitoring in step S2 is repeated until this polling frame is received.

When the control ECU 20 transmits a polling frame including the ID of each sensor 30 and an ultrasonic wave transmission command, each sensor 30 receives this polling frame at the LAN control circuit 32 via the communication D / R 31. If the polling frame is decrypted and includes the self ID, the LAN control circuit 32 returns the distance information and the noise presence / absence information previously measured and stored to the control ECU 20 (steps S3 → S4). Next, the LAN control circuit 32 transmits an ultrasonic wave transmission command to the transmission circuit 33, and the transmission circuit 33
Oscillates an ultrasonic burst wave of a resonance frequency stored in advance in the non-volatile memory 39 or the LAN control circuit 32 and outputs the ultrasonic burst wave to the microphone 34.
An ultrasonic burst wave is radiated to the detection area (step S5).

If the radiated ultrasonic wave is reflected by an obstacle in the detection area, the reflected wave is generated by the microphone 3
4 received. The gain of the received signal is adjusted by the gain adjusting circuit 37 and then applied to the comparator 38. In the comparator 38, the output of the gain adjusting circuit 37 and L
The threshold value for obstacle judgment output from the AN control circuit 32 is compared with the value adjusted by the threshold value adjusting circuit 36. Here, the gain adjusting circuit 37 and the threshold adjusting circuit 36 adjust each input signal to the gain and the adjustment value stored in the non-volatile memory 39 or the LAN control circuit 32 in advance. Then, when the reflected wave reception signal> threshold value obstacle judgment signal is received by the comparator 38 (obstacle detection signal), the distance calculation circuit 3
Sent to 5. The distance calculation circuit 35 converts the time from the start of ultrasonic oscillation to the obstacle detection signal into a distance, and the LAN control circuit 32 stores this until the next polling frame (steps S6, S7, S8) and then noise. The detection information is cleared (step S9), and then the process returns to step S2.

When the control ECU 20 receives the distance information and the noise presence / absence information transmitted in step S4, when the noise presence / absence information = noise is absent, the previous distance information is updated with the distance information and is output to the display. , On the other hand,
When noise information = noise exists, the distance information is cleared and the previous distance information is continuously held.

<Second Embodiment> FIG. 3 is a block diagram showing an obstacle detecting device according to a second embodiment, and FIG. 4 is a flow chart for explaining the processing of the sensor in FIG. As shown in FIG. 3, in the second embodiment, in comparison with the configuration shown in FIG. 1, the output of the comparator 38 is the noise detection circuit 9
It is applied to the LAN control circuit 32 via 0.

As shown in FIG. 4, in the sensor 30, when the LAN control circuit 32 receives the initialization command through the communication D / R 31, the noise monitoring operation is started (step S1).
→ S2-1). In the noise monitoring in step S2-1, ultrasonic noise reception processing is performed without transmitting ultrasonic waves by the microphone 34. The gain of the ultrasonic noise signal is adjusted by the gain adjusting circuit 37, and then the comparator 3
8 is applied.

In the comparator 38, the output of the gain adjusting circuit 37 is compared with the value adjusted by the threshold adjusting circuit 36 for the noise judgment threshold value output from the LAN control circuit 32. Here, the gain adjusting circuit 37 and the threshold adjusting circuit 36 adjust each input signal to the gain and the adjustment value stored in the non-volatile memory 39 or the LAN control circuit 32 in advance. Then, when the ultrasonic noise signal> threshold value by the comparator 38, the noise detection circuit 90 resets the internal counter and starts counting, and counts until the next polling frame is received. Measure (steps S2-2, 2-3).

Next, the polling frame of the transmission command including the self ID from the control ECU 20 is waited (step S3), and the noise monitoring in steps S2-1, 2-2, 2-3 is repeated until the polling frame is received. Then, the control ECU 20 sets the ID of each sensor 30,
When a polling frame including an ultrasonic wave transmission command is transmitted, each sensor 30 receives this polling frame by the LAN control circuit 32 via the communication D / R 31 and decodes it. The counting of the detection circuit 90 is stopped (step S4-
1), and then the LAN control circuit 32 returns the distance information and the count value (noise time information) previously measured and stored to the control ECU 20 (step S4-2). Then, the LAN control circuit 32 transmits an ultrasonic wave transmission command to the transmission circuit 33, and the transmission circuit 33 preliminarily writes the nonvolatile memory 39.
Alternatively, an ultrasonic burst wave having a resonance frequency stored in the LAN control circuit 32 or the like is oscillated and output to the microphone 34,
As a result, an ultrasonic burst wave is emitted from the microphone 34 to the detection area (step S5).

If the radiated ultrasonic wave is reflected by an obstacle in the detection area, the reflected wave is generated by the microphone 3
4, the received signal is applied to the comparator 38 after its gain is adjusted by the gain adjusting circuit 37.
In the comparator 38, the output of the gain adjusting circuit 37 and the LAN
The threshold value for obstacle judgment output from the control circuit 32 is compared with the value adjusted by the threshold value adjusting circuit 36. Here, the gain adjusting circuit 37 and the threshold adjusting circuit 3
Reference numeral 6 adjusts each input signal to a gain and an adjustment value stored in the non-volatile memory 39 or the LAN control circuit 32 in advance. Then, when the reflected wave received signal> the threshold value, the received signal (obstacle detection signal) is detected by the comparator 38 as the distance calculation circuit 3
5, the distance calculation circuit 35 converts the time from the start of ultrasonic oscillation to the obstacle detection signal into a distance, and the LAN control circuit 32 stores this until the next polling frame (steps S6, S7, S8), then clear the noise time counter (step S9 '), then step S
Return to 2-1.

When the control ECU 20 receives the transmitted distance information and noise time information in step S4, if the noise time is longer than a predetermined multipath floating time,
When it is judged that there is no noise, the previous distance information is updated based on the distance information and output to the display unit, etc. On the other hand, if the noise time is shorter than the specified multipath floating time, it is regarded as noise and the distance information is cleared. And hold the previous distance information.

Therefore, the sensor 30 is controlled by the control ECU 20.
Since the noise is monitored in advance before receiving an ultrasonic wave transmission instruction from, it is possible to speed up the response when shifting to the obstacle detection operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an obstacle detection device according to the present invention.

FIG. 2 is a flow chart for explaining processing of the sensor of FIG.

FIG. 3 is a block diagram showing an obstacle detection device according to a second embodiment.

FIG. 4 is a flowchart for explaining a process of the sensor in FIG.

[Explanation of symbols]

20 Control ECU 30 ultrasonic sensors

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G08G 1/16 G01S 7/52 JF term (reference) 5H180 AA01 CC11 FF25 FF27 FF32 5J083 AA02 AB13 AC17 AC30 AD04 AE10 AF09 BA01 BE16 BE18 CA01 EB11

Claims (4)

[Claims] 1. A sensor mounted at an obstacle detection position of a vehicle transmits an ultrasonic wave based on an ultrasonic wave transmission instruction from a control unit, and based on an obstacle detection signal by the ultrasonic wave reflected by the obstacle. Digitally calculating the distance to the obstacle and transmitting the distance information to the control unit,
An obstacle detection device in which the control unit issues an alarm based on the distance information, wherein the sensor includes a noise monitoring unit that monitors noise in advance before receiving an ultrasonic wave transmission instruction from the control unit. Detection device. 2. The obstacle detecting device according to claim 1, wherein the noise monitoring unit repeatedly monitors noise in advance before receiving an ultrasonic wave transmission instruction from the control unit. 3. The noise monitoring means returns noise detection information to the control unit together with the distance information when the ultrasonic transmission instruction is received, and the control unit,
2. The distance information is valid when the noise detection information is “no noise”, and the distance information is invalid and the previous distance information is valid when the noise detection information is “noise”. The obstacle detection device according to 2. 4. The noise monitoring means measures the time from the detection of noise to the ultrasonic wave transmission instruction, and when the ultrasonic wave transmission instruction is received, returns the response information to the control unit together with the distance information. When the measurement time is longer than the predetermined multi-path floating time, the unit determines that "no noise" and validates the distance information, and when the measurement time is shorter than the predetermined multi-path floating time, "Noise" is present. The obstacle detection device according to claim 1 or 2, wherein the distance information is invalidated and the previous distance information is validated.