JP2011209194A - Obstacle detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an obstacle detecting device, capable of accurately determining the coming of a noise affecting detection of an obstacle and accurately detecting the obstacle.SOLUTION: The obstacle detecting device for detecting obstacle by transmitting and receiving ultrasonic waves includes: a transmission means for transmitting ultrasonic waves; a reception means for receiving the ultrasonic waves reflected by the obstacle; an obstacle detection means for comparing the level of a signal received by the reception means with a noise determination threshold, and when the level of the received signal is higher than the noise determination threshold, determining that the obstacle exists; an on/off detection means for detecting whether a noise generating source whose noise level at the reception means is known is in an on state; and a threshold setting means for changing a value of the noise determination threshold according to whether the noise generation source is in an on state.

Description

  The present invention relates to an obstacle detection device, and more specifically, an obstacle detection device capable of accurately detecting the arrival of noise that affects the detection of an obstacle and accurately detecting the obstacle. About.

  An ultrasonic sensor is a sensor such as sonar that detects the presence of a surrounding object and the distance from the object by transmitting an ultrasonic wave toward the surrounding object and receiving a reflected wave from the object. In recent years, an ultrasonic sensor is provided in the front part or the rear part of a vehicle, and when the vehicle moves forward or backward, an obstacle existing in front of or behind the vehicle is detected by the ultrasonic sensor. The sensor ECU that processes the reception signal of the ultrasonic sensor compares the level of the reception signal in the ultrasonic sensor with a preset threshold value, and determines that an obstacle exists when the level of the reception signal is greater than the threshold value. By detecting an obstacle, the risk of a vehicle colliding with the obstacle can be reduced.

  However, if the vehicle has a noise generation source and the level of noise from the noise generation source is larger than the threshold, the sensor ECU may erroneously recognize the noise generation source as an obstacle.

In order to prevent such misrecognition, there have been the following techniques.
One of them is explained here. First, the sensor ECU detects the current value level of the received wave during a predetermined period immediately before the ultrasonic sensor transmits the ultrasonic wave. When the current value level is equal to or higher than the threshold value, the sensor ECU determines that high level noise has arrived and stops transmitting ultrasonic waves for a predetermined period. By stopping the transmission, the obstacle detection operation is also stopped, so that erroneous recognition of the obstacle can be prevented. However, this technique has a problem that during a predetermined period when transmission is stopped, the obstacle detection operation is forcibly stopped even if the incoming noise is weak.

  FIG. 8 is a diagram for explaining this problem. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the current value of the received wave output from the ultrasonic sensor. In the example shown in FIG. 8, a large noise A is first detected in a period T1 immediately before ultrasonic transmission. The noise A exceeds the threshold value Th1. Therefore, the sensor ECU stops the ultrasonic transmission from the ultrasonic sensor in the periods T2 and T3. In FIG. 8, for convenience of explanation, the transmission ultrasonic wave B and the reflected wave C are shown, but they are not actually transmitted and received. Since the ultrasonic transmission is stopped, the reflected wave C that should have arrived when an obstacle is present does not arrive, and the sensor ECU cannot detect the obstacle.

  This technique also has the following problems. That is, when no large noise exceeding the threshold value has arrived in the period immediately before ultrasonic transmission, the sensor ECU performs an obstacle detection operation. However, if high-level noise that exceeds the threshold value arrives during or after ultrasonic transmission (except immediately before the next ultrasonic transmission), the sensor ECU mistakes that the noise is due to the presence of an obstacle. I will judge.

  FIG. 9 is a diagram for explaining this problem. In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates the current value of the received wave output from the ultrasonic sensor. In the example shown in FIG. 9, no large noise exceeding the threshold value Th1 has arrived in the period T1 immediately before ultrasonic transmission. However, a high level of noise D that exceeds the threshold Th1 has arrived after ultrasonic transmission. In this case, the sensor ECU erroneously determines that the noise D is due to the presence of an obstacle.

  Patent Document 1 discloses a distance measuring device that measures a distance from a distance measuring object using an ultrasonic sensor. This distance measuring device receives an ultrasonic wave (reflected ultrasonic wave) reflected by a distance measuring object after transmitting an ultrasonic pulse, detects the reflected ultrasonic wave, and detects the level of the detection signal and the level of the threshold signal. Compare If the detection signal level is greater than the threshold signal level, the distance to the object to be measured is calculated based on the time from when the ultrasonic pulse is transmitted until the detection signal level first exceeds the threshold signal level. calculate. This distance measuring apparatus measures the noise level during a period in which no ultrasonic wave is transmitted, and sets the threshold signal level so that the threshold signal level does not become lower than the noise level. By making such a setting, it is possible to prevent erroneous recognition of noise as a reflected wave from the object to be measured.

  However, since the distance measuring device of Patent Document 1 measures a noise level during a period in which ultrasonic waves are not transmitted, if a large noise has arrived during ultrasonic transmission, the noise can be detected. Can not. In this case, there is a problem that the level of the threshold signal cannot be set appropriately.

Japanese Patent Laid-Open No. 08-201514

  The present invention has been made in view of such circumstances, and an obstacle capable of accurately detecting an obstacle by accurately determining that noise that affects the detection of the obstacle has arrived. An object is to provide a detection device.

The first invention is
An obstacle detection device that detects an obstacle by transmitting and receiving ultrasonic waves,
A transmission means for transmitting ultrasonic waves;
Receiving means for receiving ultrasonic waves reflected by the obstacle;
Obstacle detection means for comparing the level of the received signal in the receiving means with a noise determination threshold and determining that an obstacle is present when the level of the received signal is greater than the noise determination threshold;
On / off detection means for detecting whether or not a noise generation source whose noise level is known in the receiving means is in an on state;
It is an obstacle detection apparatus provided with the threshold value setting means which changes the magnitude | size of the said noise determination threshold value according to whether the said noise generation source is an ON state.

  According to the first invention, it is detected whether or not a noise generation source whose noise level is known in the receiving means is in an ON state. Therefore, when a noise source that generates noise that affects obstacle detection is on, the threshold setting means increases the noise determination threshold so that noise does not affect obstacle detection. In addition, the size of the noise determination threshold can be changed as appropriate. Thereby, the obstacle detection device can accurately detect the obstacle.

The second invention is
An obstacle detection device that detects an obstacle by transmitting and receiving ultrasonic waves,
A transmission means for transmitting ultrasonic waves;
Receiving means for receiving ultrasonic waves reflected by the obstacle;
Obstacle detection means for comparing the level of the received signal in the receiving means with a noise determination threshold and determining that an obstacle is present when the level of the received signal is greater than the noise determination threshold;
On / off detection means for detecting whether or not a noise generation source whose noise level is known in the receiving means is in an on state;
An obstacle detection apparatus comprising: a detection operation control unit that controls whether or not to operate the obstacle detection unit according to whether or not the noise generation source is in an on state.

  According to the second invention, it is detected whether or not a noise generating source whose noise level is known in the receiving means is in an on state. Therefore, when the noise source that generates noise that affects obstacle detection is on, the detection operation control means stops the operation of the obstacle detection means. Can not be given. Thereby, the obstacle detection device can accurately detect the obstacle.

  According to the present invention, it is possible to accurately detect the arrival of noise that affects the detection of an obstacle and reliably detect the obstacle.

The block diagram which shows the structure of the obstruction detection apparatus which concerns on 1st Embodiment in this invention. When the noise source is turned on immediately before ultrasonic transmission, the time chart showing the noise source on / off (upper stage) and the noise determination threshold are linked to the noise source on / off. The time chart (timing) which shows the timing to perform, and the figure which shows the threshold value for noise determination before and after a change which shows the ultrasonic wave which the obstacle detection apparatus shown in FIG. 1 transmits / receives with a noise When the noise source on timing is after ultrasonic transmission, the time chart showing the noise source on / off (upper stage) and the noise determination threshold in conjunction with the noise source on / off A time chart showing the timing of change (middle stage), and a diagram showing the ultrasonic wave transmitted and received by the obstacle detection device shown in FIG. 1 together with noise and showing threshold values for noise determination before and after the change (lower stage) The flowchart which shows operation | movement of the obstruction detection apparatus shown by FIG. The block diagram which shows the structure of the obstruction detection apparatus which concerns on 2nd Embodiment in this invention. Time chart showing the on / off state of the noise source (upper stage) and time chart showing the timing for changing whether the obstacle detection operation and distance measurement are performed in conjunction with the on / off state of the noise source (middle stage) And the figure which shows the ultrasonic wave which the obstacle detection apparatus shown by FIG. 5 transmits / receives with the threshold value for noise and noise determination (lower stage) The flowchart which shows operation | movement of the obstruction detection apparatus shown by FIG. Diagram explaining conventional problems Diagram explaining conventional problems

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the obstacle detection apparatus according to the first embodiment. FIG. 2 shows a time chart (upper stage) showing ON / OFF of the noise generation source when the ON timing of the noise generation source is immediately before ultrasonic transmission, and noise determination in conjunction with the ON / OFF of the noise generation source. 2 is a time chart (middle stage) showing the timing for changing the threshold for use, and a figure (lower stage) showing the sound wave transmitted and received by the obstacle detection device shown in FIG. 1 together with noise and the noise determination threshold before and after the change. . FIG. 3 shows a time chart (upper stage) showing ON / OFF of the noise generation source when the ON timing of the noise generation source is after ultrasonic transmission, and the noise in conjunction with the ON / OFF of the noise generation source. A time chart showing the timing for changing the threshold for judgment (middle stage), and a diagram showing the ultrasonic wave transmitted and received by the obstacle detection device shown in FIG. It is. FIG. 4 is a flowchart showing the operation of the obstacle detection apparatus shown in FIG.

  As shown in FIG. 1, the obstacle detection apparatus 1 according to the first embodiment is an apparatus that detects an obstacle by transmitting and receiving ultrasonic waves. The obstacle detection device 1 is mainly mounted on a vehicle, detects a detection object (an obstacle such as a wall or another vehicle) existing around the vehicle, and refers to the detection object (hereinafter referred to as an obstacle). In order to measure the distance, for example, it is arranged at the front end or the rear end of the vehicle.

  The obstacle detection apparatus 1 includes a transmission unit 2, a reception unit 3, an obstacle detection unit 4, a distance measurement unit 5, an on / off detection unit 6, a threshold setting unit 7, and a noise level storage unit 11. It has.

  The transmission unit 2 and the reception unit 3 constitute an ultrasonic sensor 8. One ultrasonic sensor 8 composed of the transmission unit 2 and the reception unit 3 may be provided, or two or more ultrasonic sensors 8 may be provided.

  The obstacle detection unit 4, the distance measurement unit 5, the on / off detection unit 6, the threshold setting unit 7, and the noise level storage unit 11 are provided in the clearance sonar ECU 9. The clearance sonar ECU 9 is composed of a microcomputer, and the obstacle detection means 4, the distance measurement means 5, the on / off detection means 6, and the threshold setting means 7 are executed, for example, by a CPU executing a program stored in the ROM. It can be realized as a functional unit.

  The transmission means 2 transmits ultrasonic waves toward the obstacle. The ultrasonic waves to be transmitted are, for example, burst ultrasonic waves that are continuous for a certain period.

  The receiving means 3 receives the ultrasonic waves reflected by the obstacle. The reception signal of the reception means 3 is output to the clearance sonar ECU 9.

  The obstacle detection unit 4 compares the level of the reception signal in the reception unit 3 with a preset threshold value Th1 (or threshold value Th2). If the level of the reception signal is greater than the threshold value Th1 (or threshold value Th2), the obstacle detection unit 4 Judge that an object exists.

  When the obstacle detection means 4 determines that an obstacle is present, the distance measuring means 5 measures the distance to the obstacle. The distance is measured by dividing by 2 the value obtained by multiplying the time from when the transmitting means 2 transmits an ultrasonic wave until the ultrasonic wave is reflected by the obstacle and received by the receiving means by the speed of sound. be able to.

  The on / off detection means 6 detects whether or not the noise generation sources 10 (10A, 10B) whose noise level is known in the reception means 3 are in the on state (see the upper part of FIG. 2). The noise generation source 10 is connected to the clearance sonar ECU 9 via a communication line 15 (for example, a CAN (Controller Area Network) communication line) of the in-vehicle LAN. In the example shown in FIG. 1, the number of noise generation sources 10 is two, but the number of noise generation sources 10 is not particularly limited, and may be one or three or more. Good. The noise generation source 10 (10A, 10B) is a system mounted on a vehicle, for example, and emits noise such as sonic noise near the ultrasonic region when it is on (during operation).

  The noise level storage means 11 generates noise when the noise generated by the noise generation source 10 when the noise generation source 10 is on is received by the reception means 3 (hereinafter referred to as reception level when on) and noise generation. A maximum reception level of noise received by the receiving means 3 when the source 10 is off (hereinafter referred to as an off-time reception level) is stored as known data.

  The threshold setting means 7 changes the size of the noise determination threshold according to whether or not the noise generation source 10 is in the on state (see FIGS. 2 and 3). In the example shown in FIG. 3, the magnitude of the noise determination threshold is changed from Th1 to Th2. The threshold setting unit 7 changes the size of the noise determination threshold based on the noise level stored in the noise level storage unit 11. For example, when the noise source 10 is off, the threshold setting unit 7 sets the noise judgment threshold value to be larger (a little larger Th1) than the OFF reception level, and when the noise source 10 is on, the noise judgment threshold value is set. Is set to be larger (slightly larger Th2) than the reception level when ON. When there are a plurality of noise generation sources 10 and the plurality of noise generation sources 10 are ON, noise generation with the maximum ON reception level among the plurality of noise generation sources 10 turned ON is generated. A noise determination threshold value may be set with the source 10 as a reference.

Next, the operation of the obstacle detection apparatus 1 will be described with reference to the flowchart of FIG.
First, it is determined whether or not the ultrasonic sensor 8 is turned on (step S1). If the ultrasonic sensor 8 is off, the determination in step S1 is repeated. On the other hand, if the ultrasonic sensor 8 is on, the on / off detection means 6 determines whether or not the noise source 10 is on (step S2).

  If the noise source 10 is off, normal logic is applied (step S3). That is, the threshold value setting means 7 sets the noise determination threshold value to be larger (slightly larger Th1) than the OFF reception level. The obstacle detection unit 4 compares the level of the reception signal in the reception unit 3 with the noise determination threshold value Th1, and determines that an obstacle exists when the level of the reception signal is greater than the noise determination threshold value Th1. The distance measuring means 5 measures the distance to the obstacle when the obstacle detecting means 4 determines that an obstacle is present.

On the other hand, when the noise source 10 is on, the logic when the noise source 10 is activated is applied (step S4). That is, the threshold value setting means 7 sets the noise determination threshold value to be larger (a little larger Th2) than the ON reception level. The obstacle detection unit 4 compares the level of the reception signal in the reception unit 3 with the noise determination threshold Th2, and determines that an obstacle is present when the level of the reception signal is greater than the noise determination threshold Th2. The distance measuring means 5 measures the distance to the obstacle when the obstacle detecting means 4 determines that an obstacle is present.
The above is the operation of the obstacle detection apparatus 1.

  According to the first embodiment, it is detected whether or not the noise generation source 10 whose noise level is known in the receiving means 3 is in the on state. Therefore, when the noise generation source 10 that generates noise that affects the detection of an obstacle is on, the threshold setting unit 7 increases the noise determination threshold, and the noise affects the detection of the obstacle. The magnitude of the noise determination threshold value can be appropriately changed so as not to give it. Thereby, the obstacle detection device 1 can accurately detect the obstacle.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram illustrating a configuration of the obstacle detection apparatus according to the second embodiment. FIG. 6 is a time chart (upper stage) showing ON / OFF of the noise generation source, and a time showing timing for changing whether or not the obstacle detection operation and the distance measurement are performed in conjunction with the ON / OFF of the noise generation source. It is a figure (lower stage) which shows the ultrasonic wave transmitted and received by the chart (middle stage) and the obstacle detection apparatus shown in FIG. FIG. 7 is a flowchart showing the operation of the obstacle detection apparatus shown in FIG.

  The second embodiment differs from the first embodiment in that a clearance sonar 16 is substituted for the clearance sonar 9, a detection operation control means 12 is substituted for the noise level storage means 11, and a threshold setting means 14 is substituted for the threshold setting means 7. The other configuration is the same as that of the first embodiment. The description of the same configuration as that of the first embodiment is omitted.

  The detection operation control means 12 controls whether the obstacle detection means 4 and the distance measurement means 5 are operated according to whether or not the noise generation source 10 is in the on state. Specifically, for example, when the noise generation source 10 is in an off state, the obstacle detection operation and the obstacle are performed in a state where the noise determination threshold is set to be larger (a little larger Th3) than the reception level when off. A distance measuring operation is performed (see FIG. 6). On the other hand, when the noise generation source 10 is in the on state, the obstacle detection operation and the distance measurement operation with the obstacle are performed while the noise determination threshold is set to be larger (a little larger Th3) than the reception level when off. It is stopped (see FIG. 6). For example, the obstacle detection operation and the distance measurement operation are stopped until the noise generation source 10 that emits noise that may be given to the obstacle detection operation and the distance measurement operation is turned off, and when the noise generation source 10 is turned off, The obstacle detection operation and the distance measurement operation are resumed.

  The threshold value setting unit 14 sets the noise determination threshold value to a constant value regardless of whether or not the noise generation source 10 is in the ON state.

Next, the operation of the obstacle detection device 13 will be described with reference to the flowchart of FIG.
First, it is determined whether or not the ultrasonic sensor 8 is turned on (step S1). If the ultrasonic sensor 8 is off, the determination in step S1 is repeated. On the other hand, if the ultrasonic sensor 8 is on, the on / off detection means 6 determines whether or not the noise source 10 is on (step S2).

  If the noise source 10 is off, normal logic is applied (step S3). That is, the noise determination threshold is set to be larger (a little larger Th3) than the OFF reception level. The obstacle detection unit 4 compares the level of the reception signal in the reception unit 3 with the noise determination threshold Th3, and determines that an obstacle exists when the level of the reception signal is greater than the noise determination threshold Th3. The distance measuring means 5 measures the distance to the obstacle when the obstacle detecting means 4 determines that an obstacle is present. After step S3, the process returns to step S1.

On the other hand, when the noise source 10 is on, the logic when the noise source 10 is activated is applied (step S4). That is, the detection operation control unit 12 stops the obstacle detection operation and the distance measurement operation with the obstacle while the noise determination threshold is set to be larger (a little larger Th3) than the reception level when off. After step S4, the process returns to step S1.
The operation of the obstacle detection device 13 has been described above.

  According to the second embodiment, it is detected whether or not the noise generation source 10 whose noise level is known in the receiving means 3 is in the ON state. Therefore, when the noise source 10 that generates noise that affects the detection of the obstacle is on, the detection operation control means 12 stops the operation of the obstacle detection means 4 and the distance measurement means 5. For example, noise can be prevented from affecting the detection of an obstacle. Thereby, the obstacle detection device 13 can accurately detect the obstacle.

  INDUSTRIAL APPLICABILITY The present invention can be used for an obstacle detection device that detects an obstacle by transmitting and receiving ultrasonic waves.

DESCRIPTION OF SYMBOLS 1,13 Obstacle detection apparatus 2 Transmission means 3 Reception means 4 Obstacle detection means 5 Distance detection means 6 On / off detection means 7, 14 Threshold setting means 8 Ultrasonic sensor 9, 16 Clearance sonar ECU
10, 10A, 10B Noise generation source 11 Noise level storage means 12 Detection operation control means

Claims (2)

An obstacle detection device that detects an obstacle by transmitting and receiving ultrasonic waves,
A transmission means for transmitting ultrasonic waves;
Receiving means for receiving ultrasonic waves reflected by the obstacle;
Obstacle detection means that compares the level of the received signal in the receiving means with a noise determination threshold and determines that an obstacle is present when the level of the received signal is greater than the noise determination threshold;
On / off detection means for detecting whether or not a noise generation source whose noise level is known in the receiving means is in an on state;
An obstacle detection device comprising: threshold setting means for changing the magnitude of the noise determination threshold depending on whether or not the noise generation source is in an on state. An obstacle detection device that detects an obstacle by transmitting and receiving ultrasonic waves,
A transmission means for transmitting ultrasonic waves;
Receiving means for receiving ultrasonic waves reflected by the obstacle;
Obstacle detection means that compares the level of the received signal in the receiving means with a noise determination threshold and determines that an obstacle is present when the level of the received signal is greater than the noise determination threshold;
On / off detection means for detecting whether or not a noise generation source whose noise level is known in the receiving means is in an on state;
An obstacle detection device comprising detection operation control means for controlling whether or not to operate the obstacle detection means depending on whether or not the noise generation source is in an on state.

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