JP2007322224A - Obstacle detector and position specifying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely detect the positions of obstacles by reducing variations of reflected waves. <P>SOLUTION: Reflected waves received by a receiving part 121 are amplified by an amplifier 122, full-wave rectified by a detection part 124, and integrated by an AD input part 127. A sensor ECU 130 therefore acquires envelope waves to distinguish the crests of the envelope waves, determine rise estimates, and store them in a candidate table. The sensor ECU 130 extracts rise estimates having differences within a prescribed range from the candidate table with reference to rise estimates determined at the previous measurement timing and sets them in an average table. In other words, rise estimates of envelope waves (candidates) of the same obstacles are sequentially set in the average table. The sensor ECU 130 computes the three-dimensional positions of the obstacles on the basis of rise estimates acquired by averaging values in the average table. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an obstacle detection device for a vehicle, and is particularly suitable for use in an obstacle detection device capable of accurately detecting the position of an obstacle by reducing the influence of variations in reflected waves and the obstacle detection device. The present invention relates to a location method.

Conventionally, various obstacle detection devices for vehicles have been devised. Some of these obstacle detection devices can detect the position of each obstacle even when the reflected waves reflected by a plurality of obstacles are received. (For example, see Patent Document 1)
JP 2002-372577 A

  In the obstacle detection device disclosed in Patent Document 1, the amplitude of the received wave differs according to the reflectance of the obstacle, or the Doppler shift occurs according to the moving speed of the obstacle, and the frequency of the received wave varies. Focusing on this, the combination of reflected waves reflected by the same obstacle is obtained.

The obstacle detection device disclosed in Patent Document 1 is characterized in that, as described above, the combination of reflected waves reflected by the same obstacle is obtained using the amplitude of the received wave and the frequency variation of the received wave. However, there are the following problems.
In this conventional obstacle detection device, a radio wave radar is used as a transmission wave, and the amplitude and frequency of the reception waveform of the reflected wave are obtained.
However, since the radio wave radar has a problem such as directivity, the reception sensitivity of the receiving unit (sensor) varies depending on the angle. In addition, if the influence of disturbance noise or the obstacle has a plurality of reflection surfaces such as a human body, the received waveform varies even if the reflected wave is from the same obstacle.
Such variations in the received waveform cause variations in the reception time (rise timing) of the reflected wave, and thus adversely affect coordinate calculation by subsequent triangulation. Also, if the amplitude etc. differ due to variations in the received waveform, even the reflected wave from the same obstacle will be mistaken as a reflected wave from another obstacle, and the accuracy of the position of each obstacle will eventually be It will fall.

  The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to detect the position of an obstacle with high accuracy by reducing the influence of variations in reflected waves.

In order to achieve the above object, an obstacle detection apparatus according to the first aspect of the present invention provides:
A transmission means for transmitting ultrasonic waves at every measurement timing;
Receiving means for receiving reflected ultrasonic waves transmitted by the transmitting means at different positions;
An envelope wave acquiring means for obtaining an envelope wave corresponding to each reflected wave based on each reflected wave received by the receiving means;
From the obtained envelope wave, estimation means for estimating the rising time of each envelope wave,
From each rise time estimated by the estimation means, an extraction means for extracting a rise time that satisfies a predetermined relationship with the rise time estimated at the previous measurement timing;
Holding means for holding the rising time extracted by the extracting means for a plurality of measurement times;
Averaging means for averaging rise times held in the holding means;
Position specifying means for specifying the position of an obstacle based on the rise time averaged by the averaging means;
It is characterized by comprising.

  For example, the extraction unit extracts a difference within a predetermined value from each rise time estimated by the estimation unit with reference to the rise time estimated at the previous measurement timing.

  For example, the extracting unit extracts a rising time satisfying a predetermined relationship from the rising times estimated by the estimating unit in preference to the one having the highest peak of the envelope wave.

For example, the envelope wave acquisition unit integrates the detection unit that rectifies each reflected wave received by the reception unit, and the reflected waveform rectified by the detection unit, respectively, and the envelope wave corresponding to each reflected wave Sampling means for sampling each of
The estimation means discriminates the apex of each envelope wave sampled by the sampling means and estimates the rising time of each envelope wave.

Further, the position specifying method according to the second aspect of the present invention is as follows:
A position specifying method in an obstacle detection device that transmits ultrasonic waves from a transmission unit at each measurement timing and receives reflected waves of the ultrasonic waves at different receiving units,
An envelope wave obtaining step for obtaining an envelope wave corresponding to each reflected wave based on each reflected wave received by each receiving unit;
From each of the obtained envelope waves, an estimation step for estimating the rising time of each envelope wave,
From each rise time determined in the estimation step, an extraction step for extracting a rise time satisfying a predetermined relationship with the rise time estimated at the previous measurement timing;
Storing the rise time extracted in the extraction step in a table and holding the rise times for a plurality of measurement times;
An averaging step for averaging rise times stored in the table;
Based on the rise time averaged in the averaging step, a position specifying step for specifying the position of the obstacle,
It is characterized by comprising.

For example, the envelope wave acquisition step rectifies each reflected wave received by each receiving unit by the detecting unit, integrates each by the AD input unit, and samples each envelope wave corresponding to each reflected wave A sampling step;
The estimation step discriminates the vertex of each envelope wave sampled in the sampling step, and estimates the rising time of each envelope wave.

According to the obstacle detection device of the present invention, it is possible to detect the position of each obstacle with high accuracy by reducing the influence due to variations in reflected waves.
Further, according to the position specifying method of the present invention, the position of each obstacle can be detected with high accuracy by reducing the influence of the variation of the reflected wave.

Hereinafter, the obstacle detection apparatus 100 according to the embodiment of the present invention will be described.
A vehicle 10 to which the obstacle detection apparatus 100 according to the present embodiment is applied is a so-called hatchback vehicle having a flip-up type PBD (Power Back Door) 11 as shown in FIGS. A center unit 110, a sensor ECU (Electronic Control Unit) 130, a PBD ECU 140, and the like are appropriately installed.

  As shown in FIG. 2, the obstacle detection apparatus 100 includes a transmitter 111, a booster coil 112, a 40 kHz transmitter 113, a burst transmitter 114, a timing circuit 115, receivers 121a to 121c, and an amplifier 122a. To 122c, BPF (Band-Pass Filter) 123a to 123c, detectors 124a to 124c, S / H (Sample and Hold) 125a to 125c, S / H trigger controller 126, and AD (Analog to Digital) ) Input units 127a to 127c, sensor ECU 130, PBD ECU 140, motor 150, and operation SW (switch) 160 are provided.

The transmission unit 111 is composed of a piezoelectric element or the like provided with a cover, oscillates according to the drive voltage supplied from the booster coil 112, and transmits ultrasonic waves (transmitted waves) through the cover functioning as a resonator.
The step-up coil 112 steps up the pulse voltage supplied from the 40 kHz transmitter 113 and supplies a drive voltage to the transmission unit 111.

The 40 kHz transmitter 113 converts the burst wave supplied from the burst transmitter 114 into a 40 kHz pulse wave and supplies it to the booster coil 112.
The burst transmitter 114 is controlled by the timing circuit 115 and supplies a burst wave to the 40 kHz transmitter 113.
The timing circuit 115 is controlled by the sensor ECU 130 to supply a burst wave from the burst transmitter 114 at regular timing (for example, 0.1 second).

The receiving unit 121 (121a to 121c) includes a piezoelectric element having a cover that functions as a resonator, and receives the reflected ultrasonic wave (the reflected wave reflected by the obstacle) transmitted by the transmitting unit 111. Then, an electromotive force (signal) corresponding to the pressure applied by receiving the reflected wave is generated, and this signal is output to the amplifier 122.
Note that the sensor unit 110 is configured by the reception unit 121, the transmission unit 111, and the like, and is installed beside the license lamp, for example, in the PBD 11, as shown in FIG.
More specifically, as shown in FIG. 3, the receiving unit 121a and the receiving unit 121b, and the transmitting unit 111 and the receiving unit 121c are arranged side by side in the vertical direction (Y-axis direction), and the receiving unit 121a. The transmitter 111, the receiver 121b, and the receiver 121c are arranged side by side in the horizontal direction (X-axis direction). That is, the receiving unit 121 and the transmitting unit 111 are arranged in a square shape.
In addition, although the case where the receiving unit 121 and the transmitting unit 111 are configured separately has been described, any one receiving unit 121 may also serve as the transmitting unit 111.

Returning to FIG. 2, the amplifier 122 (122 a to 122 c) amplifies the signal output from the receiving unit 121 and supplies the amplified signal to the BPF 123.
The BPF 123 (123a to 123c) passes only a signal in a predetermined frequency range among the signals supplied from the amplifier 122 and supplies the signal to the detection unit 124.

The detection unit 124 (124a to 124c) is composed of a full-wave rectifier circuit or the like, and full-wave rectifies the signal that has passed through the BPF 123 and supplies it to the S / H 125.
The S / H 125 (125a to 125c) is controlled by the S / H trigger control unit 126, samples the signal that has been full-wave rectified by the detection unit 124, and temporarily allows the AD input unit 127 to perform AD conversion. Hold.

The S / H trigger control unit 126 is controlled by the sensor ECU and generates a trigger signal necessary for the sample / hold performed by the S / H 125.
The AD input unit 127 (127a to 127c) includes an integration type AD converter or the like, converts an analog signal voltage into a digital voltage counter value, and supplies the digital voltage counter value to the sensor ECU 130.
The voltage counter value is obtained by amplifying the signal received by the receiving unit 121 by the amplifier 122, full-wave rectifying by the detecting unit 124, and integrating by the AD input unit 127. Wave) value.

The sensor ECU 130 controls the timing circuit 115 to transmit ultrasonic waves from the transmission unit 111 at certain measurement timings (for example, 0.1 seconds).
In addition, the sensor ECU 130 starts time measurement from the time of transmission of the ultrasonic wave by a timer circuit or the like provided therein. Then, voltage counter values of envelope waves that are effective as reflected waves and whose timer counter value is within a predetermined range and equal to or greater than a threshold value (for example, voltage counter value 6000) are sequentially acquired from the AD input unit 127, and envelopes are obtained. While identifying the peak of the wave, the rise time of the envelope wave is estimated.
For example, as illustrated in FIG. 4, the case where the reception unit 121 receives five reflected waves at the current measurement timing and envelope waves W1 to W5 are obtained from the AD input unit 127 will be described as an example. First, the sensor ECU 130 specifies vertices P1 to P5 of each envelope wave, and obtains approximate lines L1 to L5 by a least square method or the like using a voltage counter value in a predetermined range before each vertex. Then, a timer count value (zero crossing time) at which each approximate line intersects the voltage count value 0 is obtained. That is, the estimated rise values T1 to T5 of each envelope wave are specified.
The sensor ECU 130 performs such apex specification and rise estimation value specification for each reception location (the reflected waves received by the reception units 121a to 121c).
Then, the sensor ECU 130 stores the vertex timer counter value, the vertex voltage counter value, and the estimated rise value (timer counter value) in the candidate table.
For example, the sensor ECU 130 secures an area of the candidate table 200 as shown in FIG. 5 in the internal memory, and calculates each data (vertex for each envelope wave) calculated for the corresponding reception location (reception units 121a to 121c). Timer counter value, apex voltage counter value, and rise time estimated value).

Further, the sensor ECU 130 sets only the estimated rise value satisfying a predetermined condition from the estimated rise value of each candidate in the candidate table 200 in the average table.
For example, the sensor ECU 130 secures an area of the average table 300 as shown in FIG. 6 in the internal memory. This average table 300 corresponds to each candidate. Then, the estimated rise value obtained at the current measurement timing is compared with the estimated rise value at the previous measurement timing, and within a predetermined upper and lower limit range (for example, the sound is transmitted through the interval D between the receiving units 121. Only the estimated rise value in the range of +200 to -200 corresponding to the time to be added is added to the average table 300 and set.
Specifically, the case where the values shown in FIG. 7A are obtained in the candidate table 200 at the current measurement timing in the state where the average table 300 is shown in FIG. 6 will be described as an example. The ECU 130 uses the estimated rise value at the measurement timing 1 in FIG. 6 (that is, the estimated rise value at the previous measurement timing) as a reference, and estimates the estimated rise value within 200 from the candidate table 200 in FIG. Extract. Then, as shown in FIG. 7B, the extracted estimated rise value is set at the measurement timing 2 of the average table 300.

Note that if there is a candidate (difference estimated value with a difference greater than 200) that is not close to any of the previous measurement timings at the current measurement timing, it is added as a new candidate.
The sensor ECU 130 performs such extraction of the estimated rise value and setting to the average table 300 for each candidate.
In addition, since such an average table 300 is finite due to limitations on capacity and the like, priority is given to those with a high voltage count value at the apex, so that up to a predetermined number of rises are set in the estimated value average table 300. Also good.

  Then, the sensor ECU 130 uses the average table 300 that is updated (added) at each measurement timing in this way, and obtains the average of the estimated rising values as shown in FIG. That is, in order to reduce the variation in the waveform of the reflected wave (envelope wave), an averaged rise estimation value is obtained.

After that, when the sensor ECU 130 appropriately selects an appropriate combination from the candidates, the estimated rise value as shown in FIG. 7C is used as the reflected wave reception time, and the third order of the obstacle in the manner of triangulation. The original position is calculated.
That is, as shown in FIG. 8, the position y (coordinate value) in the Y-axis direction and the position (distance z) in the Z-axis direction of the obstacle B are obtained based on the reception times at the receiving unit 121a and the receiving unit 121b. it can.
More specifically, the following formula is established.

L1 = C · T1 / 2
L2 = C · T2-L1

L1: Distance between receiving unit 121b and obstacle B L2: Distance between receiving unit 121a and object B C: Ultrasonic velocity T1: Estimated rising value of reflected wave (envelope wave) received by receiving unit 121a T2: Estimated rising value of reflected wave (envelope wave) received by receiver 121b

Here, if D is the distance between the receiving unit 121a and the receiving unit 121b, y and z are expressed by the following equations.
y = D / 2− (D2 + L22−L12) / (2 · D)
z = √ {L22 − ((D2 + L22−L12) / (2 · D) 2}

  Similarly, the position x (coordinate value) in the X-axis direction and the position (distance z) in the Z-axis direction of the obstacle B can be obtained based on the reception times at the receiving unit 121b and the receiving unit 121c.

When the three-dimensional positions of the obstacles are obtained using the averaged estimated rising values in this way, the sensor ECU 130 stores them in the obstacle position table.
For example, the sensor ECU 130 secures the area of the obstacle position table 400 as shown in FIG. 9 in the internal memory, and sets the three-dimensional position (x position, y position, z position) of each obstacle.
The position of the obstacle obtained in this way is obtained based on the estimated rise value averaged in order to reduce the variation of the reflected wave, and therefore has high accuracy.

  When the obtained obstacle position (in the case of plural obstacles, the position of any obstacle) is in the vicinity of the PBD 11 (for example, within the opening / closing range), the sensor ECU 130 sends the obstacle detection signal to the PBD ECU 140. Supply.

In response to the instruction signal from the operation SW 160, the PBD ECU 140 drives the motor 150 to open and close the PBD 11 described above.
The PBD ECU 140 supplies the sensor ECU 130 with a door angle signal of the PBD 11 to be opened and closed. Further, when an obstacle detection signal is supplied from the sensor ECU 130, the motor 150 is stopped.

The motor 150 is controlled and driven by the PBD ECU 140 to open and close the PBD 11.
The operation SW 160 is operated by the user and supplies an instruction signal to the PBD ECU 140.

Next, the operation of the obstacle detection apparatus 100 configured as described above will be described.
The obstacle detection device 100 starts the obstacle detection process shown in the flowchart of FIG. 10 when, for example, the vehicle 10 moves backward (reverse) or when the PBD 11 is opened or closed. Note that this obstacle detection process is repeatedly executed at each measurement timing until the backward movement of the vehicle 10 and the opening / closing of the PBD 11 are completed.

  First, the sensor ECU 130 controls the timing circuit 115 to transmit ultrasonic waves from the transmission unit 111 (step S11). At the same time, the sensor ECU 130 starts time measurement (step S12). That is, the counting of the time counter value from the time of transmitting the ultrasonic wave is started.

  The sensor ECU 130 waits for subsequent processing until the timer counter value becomes equal to or greater than a predetermined value (step S13). That is, it waits until an effective reflected wave can be received.

When the timer counter value becomes equal to or larger than the predetermined value, the sensor ECU 130 specifies the peak of the waveform that exceeds a threshold (for example, the voltage counter value 6000), obtains the estimated rise value, and stores it in the candidate table 200 (step S14). .
That is, when the vertex of the envelope wave is specified, the sensor ECU 130 obtains an approximate straight line that approximates the rising portion near the vertex, and obtains a zero crossing time at which the approximate straight line intersects with the voltage counter value 0, thereby obtaining the envelope wave. Estimate the rise time of
Then, the sensor ECU 130 stores the vertex timer counter value, the vertex voltage counter value, and the estimated rise value (timer counter value) in the candidate table 200 described above.

The sensor ECU 130 compares the estimated rise value stored in the candidate table 200 with the estimated rise value obtained at the previous measurement timing, and adds only the estimated rise value within the predetermined range to the average table 300 for setting. (Step S15).
That is, with reference to the estimated rise value stored in the average table 300 at the previous measurement timing, the estimated rise value within a difference of, for example, 200 is extracted from the candidate table 200 set at the current measurement timing. Then, the extracted estimated rise value is added to the average table 300 and set.

The sensor ECU 130 obtains an average of the estimated rise values stored in the average table 300 (step S16).
That is, in order to reduce the variation in the reflected wave (envelope wave), an averaged rise estimation value is obtained.

The sensor ECU 130 selects an appropriate combination from the candidates, and calculates the three-dimensional position of the obstacle using the averaged estimated rise value (step S17).
That is, when an appropriate combination is appropriately selected from the candidates, the three-dimensional position of the obstacle is calculated in the manner of triangulation using the averaged estimated rising value as the reception time of the reflected wave.
In addition, when the position of the specified obstacle is in the vicinity of the PBD 11, the sensor ECU 130 supplies an obstacle detection signal to the PBD ECU 140 to prevent contact with the obstacle.

In such an obstacle detection process, a rising estimated value of a candidate reflected wave (envelope wave) is added to the average table 300 at each measurement timing. Since the estimated rising values are averaged, the variation in the waveform of the reflected wave (envelope wave) is reduced. Therefore, even when sudden disturbance noise, multiple reflections due to bumpers, license plates, etc. occur, the influence can be reduced.
The final obstacle position is obtained based on the estimated rise value with reduced waveform variation, and therefore has high accuracy.

The present invention is not limited to the above embodiments, and various modifications and applications are possible.
For example, in the above description, the case where ultrasonic waves are used has been described, but the present invention can be appropriately applied even when laser light or electromagnetic waves are used in addition to ultrasonic waves.

  In the above description, the present invention is applied when the vicinity of the PBD 11 is monitored. However, the sensor unit may be disposed on a door mirror or the like and used to monitor an obstacle near each door.

  In the above description, the case where the envelope wave is obtained by rectifying the received reflected wave and then integrating the rectified signal has been described. Instead, the received reflected wave is sampled and integrated. Then, it is possible to obtain an envelope wave by rectification.

  The above-described system configuration and flowchart are examples, and can be arbitrarily changed.

(A) And (b) is the schematic of the vehicle which concerns on embodiment of this invention. It is a block diagram of the obstacle detection apparatus which concerns on embodiment of this invention. It is a top view of a sensor unit. It is a figure for demonstrating the standup estimated value obtained by the approximate straight line of each waveform. It is a figure which shows an example of a candidate table. It is a figure which shows an example of an average table. (A)-(c) is a figure for demonstrating a mode until it averages a rising estimated value. It is a figure for demonstrating the method of calculating | requiring the position of an obstruction. It is a figure which shows an example of an obstruction position table. It is a flowchart for demonstrating an obstruction detection process.

Explanation of symbols

10 Vehicle 11 PBD
111 Transmitter (transmission means)
121a to 121c receiving section (receiving means)
124a to 124c detector (detection means, envelope wave acquisition means)
127a-127c AD input part (sampling means, envelope wave acquisition means)
130 sensor ECU (estimating means, extracting means, holding means, averaging means, position specifying means)

Claims (6)

A transmission means for transmitting ultrasonic waves at every measurement timing;
Receiving means for receiving reflected ultrasonic waves transmitted by the transmitting means at different positions;
An envelope wave acquiring means for obtaining an envelope wave corresponding to each reflected wave based on each reflected wave received by the receiving means;
From the obtained envelope wave, estimation means for estimating the rising time of each envelope wave,
From each rise time estimated by the estimation means, an extraction means for extracting a rise time that satisfies a predetermined relationship with the rise time estimated at the previous measurement timing;
Holding means for holding the rising time extracted by the extracting means for a plurality of measurement times;
Averaging means for averaging rise times held in the holding means;
Position specifying means for specifying the position of an obstacle based on the rise time averaged by the averaging means;
An obstacle detection device comprising:   2. The extraction means according to claim 1, wherein a difference within a predetermined value is extracted from each rising time estimated by the estimating means with reference to the rising time estimated at the previous measurement timing. The obstacle detection device described.   The extraction means extracts the rising time satisfying a predetermined relationship in preference to the one having the largest peak of the envelope wave from the rising times estimated by the estimating means. The obstacle detection apparatus according to claim 1. The envelope wave acquisition means integrates the respective reflected waveforms rectified by the detection means and the detection means for rectifying each reflected wave received by the receiving means, respectively, and each envelope wave corresponding to each reflected wave is obtained. Sampling means for sampling, and
4. The estimation unit according to claim 1, wherein the estimation unit discriminates a vertex of each envelope wave sampled by the sampling unit and estimates a rising time of each envelope wave. The obstacle detection device according to item. A position specifying method in an obstacle detection device that transmits ultrasonic waves from a transmission unit at each measurement timing and receives reflected waves of the ultrasonic waves at different receiving units,
An envelope wave obtaining step for obtaining an envelope wave corresponding to each reflected wave based on each reflected wave received by each receiving unit;
From each of the obtained envelope waves, an estimation step for estimating the rising time of each envelope wave,
From each rise time determined in the estimation step, an extraction step for extracting a rise time satisfying a predetermined relationship with the rise time estimated at the previous measurement timing;
Storing the rise time extracted in the extraction step in a table and holding the rise times for a plurality of measurement times;
An averaging step for averaging rise times stored in the table;
Based on the rise time averaged in the averaging step, a position specifying step for specifying the position of the obstacle,
A position specifying method characterized by comprising: The envelope wave acquiring step is a sampling step in which each reflected wave received by each receiving unit is rectified by a detecting unit, integrated by an AD input unit, and an envelope wave corresponding to each reflected wave is sampled. Have
6. The position specifying method according to claim 5, wherein the estimating step is to determine a vertex of each envelope wave sampled in the sampling step and estimate a rising time of each envelope wave. .

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