JP2010014497A - Obstacle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compensate a change in physical property of a wall member due to variation of an ambient temperature to improve accuracy in detecting the existence of an obstacle in an obstacle detector using the wall member as a transmission path of vibration. <P>SOLUTION: The obstacle detector is equipped with a transmission means attached to an internal surface of a resin wall member and transmitting ultrasonic waves via the wall member, and a reception means attached to the internal surface of the wall member and receiving the ultrasonic waves via the wall member. The detector includes a first reception means attached to a different location from the transmission means as a reception means; a propagation detecting means for detecting a first reception signal generated along with ultrasonic wave transmission and caused by propagation vibration propagated through the wall member among the reception signals of the first reception means; a temperature information detecting means for detecting, based on the first reception signal, temperature information which varies due to an ambient temperature; a threshold value setting means for setting a threshold value in accordance with temperature information; and a determining means for determining existence of the obstacle based on the results of comparison by comparing a second reception signal by a reflected wave of the obstacle detected in the reception means with the threshold value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an obstacle detection device.

  For example, as an obstacle detection device that detects obstacles around a vehicle, as shown in Patent Document 1, an apparatus that corrects the influence of changes in ambient temperature and detects the position of an obstacle with high accuracy is provided. Proposed.

In the obstacle detection device shown in Patent Document 1, the ultrasonic velocity value is calculated based on the time when the ultrasonic wave receiving unit receives the direct wave among the ultrasonic waves transmitted from the ultrasonic wave transmitting unit. The distance from the obstacle is calculated from the sound velocity value and the reception time of the reflected wave. According to this, the position detection of the obstacle can be performed by correcting the change in the sound velocity of the ultrasonic wave due to the change in the ambient temperature.
JP 2002-131417 A

  In recent years, in the obstacle detection device, from the viewpoint of design, a structure in which the ultrasonic sensor having the ultrasonic transmission means and the ultrasonic reception means described above is not exposed to the outside from the wall member to which the ultrasonic sensor is attached is required. It has been. In such an ultrasonic sensor mounting structure, the wall member serves as a vibration transmission path when ultrasonic waves are transmitted and received.

By the way, in a wall member made of resin such as a vehicle bumper, its physical property (Young's modulus) changes depending on the ambient temperature. Specifically, the Young's modulus decreases as the temperature increases, and the Young's modulus increases as the temperature decreases. Further, as shown in the following equation, it is known that the vibration speed (bending vibration) Cb of the wall member made of resin is proportional to the fourth power of the Young's modulus E. In Equation 1, f is the operating frequency, t is the thickness of the wall member, ρ is the density of the wall member, and ν is the Poisson's ratio of the wall member.
(Equation 1) Cb = [(π ² f ² t ² E) / {3ρ (1-ν ² )}] ^1/4
Thus, when the ambient temperature changes, the Young's modulus of the resin constituting the wall member changes and the vibration of the wall member changes. Therefore, even if a configuration in which the wall member is used as a vibration transmission path at the time of ultrasonic transmission / reception is applied to the obstacle detection device shown in Patent Document 1, the vibration waveform of the wall member changes depending on the ambient temperature. It becomes difficult to accurately detect the presence or absence of an obstacle regardless of the ambient temperature.

  The present invention has been made in view of the above points, and in an obstacle detection device using a wall member as a vibration transmission path, it detects the presence or absence of an obstacle by correcting a change in physical properties of the wall member due to a change in ambient temperature. The purpose is to improve accuracy.

  In order to achieve the above-described object, the invention according to claim 1 is attached to the inner surface of the wall member made of resin, and transmitting means for transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path; An obstacle detection device, comprising: at least one receiving unit that is attached to the inner surface of the wall member, receives ultrasonic waves by using the wall member as a vibration transmission path, and outputs a received signal. The first receiving means is mounted at a position different from the transmitting means in the above, and of the received signal of the first receiving means, it is caused by the ultrasonic vibration of the transmitting means, and is caused by the propagation vibration propagated through the wall member Propagation detecting means for detecting the first received signal, temperature information detecting means for detecting temperature information that varies depending on the ambient temperature based on the first received signal, and a predetermined threshold corresponding to the temperature information is set. A threshold setting means, a second reception signal based on the reflected wave of the obstacle detected by the reception means, and a determination means for comparing the set threshold and determining the presence or absence of an obstacle based on the result; It is characterized by providing.

  In the present invention, the transmission means transmits ultrasonic waves to the outside of the wall member through the wall member, and the reception means receives the reflected wave from the obstacle through the wall member. That is, the transmission means and the reception means are not visible from the outside of the wall member. Thereby, the designability is improved.

  Further, the first receiving means as the receiving means attached at a position different from the transmitting means on the inner surface of the wall member can detect the propagation vibration of the wall member caused by the transmission of the ultrasonic wave by the transmitting means. . This propagation vibration is propagated around the attachment portion of the transmission member on the wall member. Therefore, the physical property (Young's modulus) of the resin constituting the wall member, that is, the ambient temperature is reflected in the first received signal that is the received signal of the propagation vibration. In the present invention, the propagation detection means can detect the first reception signal among the reception signals of the first reception means.

  Further, the temperature information detecting means detects temperature information that varies depending on the ambient temperature based on the first reception signal in which the ambient temperature is reflected, and according to the temperature information, the threshold value setting means detects the temperature information in the determining means. A predetermined threshold value used for comparison with the second received signal can be set.

  As described above, in the present invention, the first receiving means detects the propagation vibration of the wall member that varies depending on the ambient temperature, the propagation detecting means detects the first received signal due to the propagation vibration, and the temperature information detecting means Thus, temperature information based on the first received signal can be detected, and a threshold value setting unit can set a predetermined threshold value corresponding to the temperature information. That is, the threshold value used for determining the presence or absence of an obstacle can be set as appropriate according to the ambient temperature. Therefore, although it is an obstacle detection device using the wall member as a vibration transmission path, it is possible to accurately detect the presence or absence of an obstacle by correcting a change in physical properties of the wall member due to a change in ambient temperature.

  In the invention described in claim 1, for example, as described in claim 2, the threshold setting unit includes a storage unit in which a correspondence table of temperature information and a threshold value associated with the temperature information is stored. It is also good. According to this, the threshold value setting means can set a predetermined threshold value corresponding to the temperature information by the correspondence table stored in the storage means.

  Next, the invention according to claim 3 is attached to the inner surface of the wall member made of resin, and is attached to the inner surface of the wall member, transmitting means for transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path. An obstacle detection device comprising: at least one receiving means for receiving ultrasonic waves using the wall member as a vibration transmission path and outputting a reception signal, wherein the receiving means is different from the transmitting means on the inner surface of the wall member. A first receiving means that is attached to the position, and that is generated by ultrasonic transmission of the transmitting means among the received signals of the first receiving means, Propagation detecting means for detecting, temperature information detecting means for detecting temperature information that varies depending on the ambient temperature based on the first received signal, and second reception by the reflected wave of the obstacle detected by the receiving means signal Amplifying means for amplifying, gain setting means for setting the gain of the amplifying means in accordance with temperature information, a second received signal amplified by the amplifying means and a predetermined threshold value are compared, and a fault is determined based on the result. Determining means for determining the presence or absence of an object.

  Also in the present invention, as in the first aspect of the present invention, the wall member serves as a vibration transmission path when transmitting or receiving ultrasonic waves, thereby improving the design. Further, the first receiving means as the receiving means attached at a position different from the transmitting means on the inner surface of the wall member can detect the propagation vibration of the wall member caused by the transmission of the ultrasonic wave by the transmitting means. . Further, the propagation detection means detects the first reception signal of the reception signals of the first reception means, and the temperature information detection means detects the ambient temperature based on the first reception signal reflecting the ambient temperature. Can be detected.

  In the present invention, the gain setting means can set the gain of the amplification means for amplifying the second received signal in accordance with the temperature information detected by the temperature information detection means. As described above, in the present invention, the first receiving means detects the propagation vibration of the wall member that varies depending on the ambient temperature, the propagation detecting means detects the first received signal due to the propagation vibration, and the temperature information detecting means Thus, temperature information based on the first received signal can be detected, and a predetermined gain corresponding to the temperature information can be set by the gain setting means. That is, the degree of amplification of the second received signal used for determining the presence or absence of an obstacle can be appropriately set according to the ambient temperature. Therefore, although it is an obstacle detection device using the wall member as a vibration transmission path, it is possible to accurately detect the presence or absence of an obstacle by correcting a change in physical properties of the wall member due to a change in ambient temperature.

  In the invention described in claim 3, for example, as described in claim 4, the gain setting means includes a storage means in which a correspondence table of temperature information and gains associated with the temperature information is stored. It is also good. According to this, the gain setting means can set a predetermined gain according to the temperature information by the correspondence table stored in the storage means.

  Next, the invention according to claim 5 is attached to the inner surface of the wall member made of resin, and is attached to the inner surface of the wall member, transmitting means for transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path. An obstacle detection device comprising: at least one receiving means for receiving ultrasonic waves using the wall member as a vibration transmission path and outputting a reception signal, wherein the receiving means is different from the transmitting means on the inner surface of the wall member. A first receiving means that is attached to the position, and that is generated by ultrasonic transmission of the transmitting means among the received signals of the first receiving means, Depending on the temperature information, at least one of the propagation detection means for detecting, the drive signal generating means for generating a drive signal for transmitting ultrasonic waves by the transmitting means, and the voltage, the number of pulses, and the frequency of the drive signal A determination to determine the presence / absence of an obstacle based on the result of comparing a predetermined threshold with the driving signal setting means to be set and the second received signal detected by the receiving means by the reflected wave of the obstacle. And means.

  Also in the present invention, as in the first aspect of the present invention, the wall member serves as a vibration transmission path when transmitting or receiving ultrasonic waves, thereby improving the design. Further, the first receiving means as the receiving means attached at a position different from the transmitting means on the inner surface of the wall member can detect the propagation vibration of the wall member caused by the transmission of the ultrasonic wave by the transmitting means. . Further, the propagation detection means detects the first reception signal of the reception signals of the first reception means, and the temperature information detection means detects the ambient temperature based on the first reception signal reflecting the ambient temperature. Can be detected.

  In the present invention, the voltage, the number of pulses, and the frequency of the drive signal for driving the transmission means to transmit the ultrasonic wave according to the temperature information detected by the temperature information detection means by the drive signal setting means At least one of the following can be set. As described above, in the present invention, the first receiving means detects the propagation vibration of the wall member that varies depending on the ambient temperature, the propagation detecting means detects the first received signal due to the propagation vibration, and the temperature information detecting means Temperature information based on the first received signal is detected, and at least one of a predetermined drive signal voltage, a predetermined number of pulses, and a predetermined frequency corresponding to the temperature information is set by the drive signal grounding means. it can. That is, the ultrasonic wave (transmission wave) that is the source of the reflected wave used for determining the presence or absence of an obstacle can be set as appropriate according to the ambient temperature. Therefore, although it is an obstacle detection device using the wall member as a vibration transmission path, it is possible to accurately detect the presence or absence of an obstacle by correcting a change in physical properties of the wall member due to a change in ambient temperature.

  In the fifth aspect of the present invention, for example, as described in the sixth aspect, the drive signal setting means includes at least one of temperature information and the voltage, number of pulses, and frequency of the drive signal associated with the temperature information. It is good also as a structure provided with the memory | storage means in which the corresponding | compatible correspondence table was memorize | stored. According to this, the drive signal setting means sets predetermined drive information (at least one of the voltage of the drive signal, the number of pulses, and the frequency) according to the temperature information by the correspondence table stored in the storage means. Can do.

  In the invention according to any one of claims 1 to 6, for example, as described in claim 7, the propagation detecting means is based on at least one of the amplitude and arrival time of the received signal by the first receiving means. What is necessary is just to set it as the structure which detects a 1st received signal.

  When the detection timing of the propagation vibration and the reflected wave by the first receiving means is different, the first reception signal due to the propagation vibration can be detected based on the arrival time. Even if at least a part of the detection of the reflected wave and the detection of the propagation vibration overlap, the energy received by the first receiving means differs between the propagation vibration and the reflected wave. Therefore, the first received signal is changed based on the amplitude. Can be detected.

  In the invention according to any one of claims 1 to 7, the temperature information detecting means may detect the amplitude of the first received signal as the temperature information as described in claim 8, or claim 9 As described above, the arrival time of the first received signal may be detected. In addition, as described in claim 10, the phase difference of the first reception signal with reference to the drive signal applied to the transmission means may be detected. Amplitude (signal strength), arrival time, and phase difference all change due to changes in the Young's modulus of the wall member due to changes in the ambient temperature. By using these as temperature information, the wall due to changes in the ambient temperature It is possible to accurately detect the presence or absence of an obstacle by correcting the physical property change of the member.

  The invention according to any one of claims 1 to 10 is suitable for a configuration in which the wall member is a bumper of a vehicle.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of an obstacle detection apparatus according to the first embodiment of the present invention. FIG. 2 is a plan view of the obstacle detection device shown in FIG. 1, showing an outline of a structure for attaching an ultrasonic sensor to a bumper. 3 is a cross-sectional view taken along the line III-III shown in FIG. In FIG. 3, for convenience, the ultrasonic sensor is illustrated in a simplified manner. FIG. 4 is a timing chart of a received signal by the transmitting element. FIG. 5 is a timing chart of ultrasonic transmission of the transmitting element and propagation vibration reception of the receiving element. FIG. 6 is a diagram illustrating the relationship between the reflected signal of the transmission element and the threshold voltage. In the present embodiment, as an obstacle detection device, an example of a vehicle obstacle detection device in which an ultrasonic sensor is attached to a bumper of a vehicle is shown.

  As shown in FIG. 1, the obstacle detection device 1 according to the present embodiment includes two ultrasonic sensors 11 and 12 as sensing units, and the ultrasonic sensor 11 includes a transmitting element 21 as a transmitting unit. The ultrasonic sensor 12 has a receiving element 22 as a first receiving means. As these elements 21 and 22, for example, piezoelectric elements using a sintered body of piezoelectric ceramics such as PZT or barium titanate can be employed.

  As shown in FIGS. 2 and 3, the ultrasonic sensors 11 and 12 are attached to an inner surface 51 of a resin bumper 50 made of, for example, polypropylene so as to be separated from each other. Thereby, at the time of transmitting an ultrasonic wave (transmission wave), the driving vibration of the transmitting element 21 is transmitted to the bumper 50, and the vibration of the bumper 50 is transmitted to the outside of the vehicle as a transmission wave. Further, when receiving the reflected wave of the transmission wave reflected by the obstacle 70, the bumper 50 vibrates due to the reflected wave, and this vibration is transmitted to the receiving element 22 so that the vibration is converted into an electric signal. It has become. That is, the bumper 50 functions as a diaphragm. Furthermore, when transmitting an ultrasonic wave (transmission wave), the vibration of the bumper 50 is propagated from the attachment site of the ultrasonic sensor 11 to the surroundings, and this propagated vibration reaches the receiving element 22 and is converted into an electric signal. It has become so.

  The positional relationship between the ultrasonic sensors 11 and 12 is close to each other while being separated from each other, specifically, the two ultrasonic sensors 11 and 12 are both in the vehicle front portion, the vehicle rear portion, and the same corner portion. It is preferable to have a configuration provided in either. In the present embodiment, the two ultrasonic sensors 11 and 12 are arranged along the horizontal direction with respect to the ground in the rear part of the vehicle between the rear corners. In the present embodiment, the attachment site of each ultrasonic sensor 11, 12 on the inner surface 51 of the bumper 50 is surrounded by an annular groove 52 adjacent to the site, and the outer periphery of the attachment site of each ultrasonic sensor 11, 12. The shape is a substantially rectangular plane that is longer in the vertical direction than in the horizontal direction. Thereby, the directivity of ultrasonic waves is narrow in the vertical direction and wide in the horizontal direction.

  Further, as shown in FIG. 1, the obstacle detection device 1 includes a drive signal generation unit 31 as a drive signal generation unit, a reception signal determination unit 32 as a propagation detection unit, and temperature information as a temperature information detection unit. It has a detection unit 33, a threshold setting unit 34 as a threshold setting unit and a memory 35, an amplification unit 36 that amplifies the reflected signal, a comparison unit 37 and a determination unit 38 as determination units.

  The drive signal generation unit 31 receives an instruction signal from a drive signal generation instruction unit (not shown), generates a drive signal in which a voltage, a frequency, and a pulse number are set in advance, and applies the drive signal to the transmission element 21. The transmitting element 21 is driven to vibrate. The drive signal generation unit 31 may be included in the ultrasonic sensor 11 together with the transmission element 21 or may be arranged separately from the ultrasonic sensor 11.

  The reception signal determination unit 32 determines the arrival time, which is the time from the start of applying the drive signal (when transmitting ultrasonic waves) to the start of signal detection, and the amplitude of the detected signal (in other words, peak value, output voltage). Based on at least one of the above, the propagation signal as the first reception signal due to the propagation vibration described above is detected among the reception signals of the receiving element 22. In the present embodiment, the reflected signal that is the second received signal by the reflected wave is also detected from the received signals of the receiving element 22. That is, the propagation signal and the reflection signal are determined from the reception signal of the reception element 22.

  Here, as shown in FIG. 3, the propagation distance of the propagation vibration, that is, the distance between the ultrasonic sensor 11 including the transmitting element 21 and the ultrasonic sensor 12 including the receiving element 22, and the ultrasonic sensor 11 The propagation distance of the propagation vibration is shorter in the sum of the distance to the obstacle 70 and the distance from the obstacle 70 to the ultrasonic sensor 12, that is, the propagation distance of the ultrasonic wave of the transmitted wave and the reflected wave.

Further, the velocity Cb of propagation vibration (bending vibration) propagating through the bumper 50 and the speed of sound C in the air are as shown by the following equations, respectively. In Equation 2, f is the frequency used, t is the thickness of the bumper 50, E is the Young's modulus of the bumper 50, ρ is the density of the bumper 50, ν is the Poisson's ratio of the bumper 50, and in Equation 3, T is Ambient temperature.
(Equation 2) Cb = [(π ² f ² t ² E) / {3ρ (1-ν ² )}] ^1/4
(Expression 3) C = 331.5 + 0.61 × T
As shown in Formula 2, the velocity Cb of the propagation vibration of the bumper 50 is proportional to the fourth power of the Young's modulus E of the resin constituting the bumper 50. The Young's modulus E is smaller as the temperature is higher. The lower the temperature, the larger the speed Cb. The higher the temperature, the slower the speed Cb, and the lower the temperature, the faster the speed Cb. Further, as shown in Formula 3, the sound speed C increases as the temperature increases and decreases as the temperature decreases.

  Furthermore, the propagation vibration is transmitted from the attachment site of the ultrasonic sensor 11 to the surroundings when the driving vibration of the transmitting element 21 is transmitted to the bumper 50 when transmitting the ultrasonic wave. The drive vibration of the transmitting element 21 is transmitted to the bumper 50, which causes a change in density in the air outside the vehicle. And, in the propagation vibration, energy attenuation due to propagation through the bumper 50 and energy attenuation due to propagation of ultrasonic waves (transmission wave and reflected wave) in the air, the propagation vibration is the amount of energy attenuation. Less is. That is, in the propagation vibration and the reflected wave, the energy received by the receiving element 22 is larger in the propagation vibration.

  Therefore, the reception signal determination unit 32 detects the propagation signal due to the propagation vibration and the reflection signal due to the reflection wave at the arrival time described above when the detection timing of the propagation vibration and the reflection wave by the receiving element 22 is different. Can do. Further, when at least a part of the reflected wave and the propagation vibration overlap, the propagation signal due to the propagation vibration and the reflection signal due to the reflection wave can be detected based on the amplitude of the signal.

  As shown in the present embodiment, in the bumper 50 made of polypropylene, the bending vibration speed Cb of the bumper 50 is faster than the sound speed C in the air in the entire assumed use temperature range of the vehicle (for example, −30 ° C. to 80 ° C.). . This has also been confirmed by the inventor. As a result, as shown in FIG. 4, the received signal of the receiving element 22 is always preceded by the propagated signal rather than the reflected signal, and the two signals do not overlap. Therefore, each of the propagation signal and the reflection signal can be easily detected. In this embodiment, the propagation signal and the reflection signal are detected at the arrival time. In the case of polyethylene having a small Young's modulus (a smaller Young's modulus than polypropylene) among general-purpose resins, the flexural vibration velocity Cb and the sound velocity C in the air are almost the same at 80 ° C. However, for example, in midsummer hot weather, the temperature (air temperature) is about 40 ° C. at the maximum, while the temperature of the bumper 50 rises to a temperature higher than the temperature. Therefore, even if polyethylene having a low Young's modulus is applied among general-purpose resins, the bending vibration speed of the bumper 50 is higher than the speed of sound C in the air over the entire assumed operating temperature range of the vehicle (for example, −30 ° C. to 80 ° C.). Since Cb is substantially faster, the reflected signal and the propagated signal do not overlap.

  Based on the propagation signal detected (determined) by the reception signal determination unit 32, the temperature information detection unit 33 detects temperature information that changes due to the ambient temperature, that is, changes due to transmission of the bumper 50. The temperature information includes, for example, the amplitude of the propagation signal (in other words, the peak value and the output voltage), the arrival time of the propagation vibration based on the start of application of the drive signal (when transmitting the ultrasonic wave), and the start of application of the drive signal, for example. Any of the phase differences of the propagation signal with reference to the above is detected.

  Here, since the propagation vibration propagates through the bumper 50 made of resin, the vibration is affected by the physical property (Young's modulus) of the resin of the bumper 50 that varies depending on the ambient temperature. Since the amplitude, arrival time, and phase difference of the propagation signal all change according to the Young's modulus of the bumper 50, assuming that these are temperature information, the physical property change of the bumper 50 due to the change of the ambient temperature is corrected, and the obstacle The presence or absence of 70 can be accurately detected.

  In the present embodiment, the arrival time is used as temperature information. As shown in Equation 2, the velocity Cb of the bending vibration propagating through the bumper 50 is proportional to the fourth power of the Young's modulus E of the resin constituting the bumper 50, and is slower as the temperature is higher and faster as the temperature is lower. Become. Therefore, when the ambient temperature changes, as shown in FIG. 5, the propagation vibration arrival time changes accordingly. In FIG. 5, the relationship between the ambient temperatures T1, T2, and T3 is T1 <T2 <T3, and the relationship between the arrival times t1, t2, and t3 is t1 <t2 <t3 according to this temperature relationship. ing. That is, the higher the ambient temperature, the longer the arrival time.

  The threshold setting unit 34 is a part for setting a threshold used for comparison with the reflected signal amplified by the amplification unit 36. The threshold setting unit 34 sets a predetermined threshold corresponding to the temperature information detected by the temperature information detection unit 33. In the present embodiment, the memory 35 stores in advance a correspondence table of arrival times as temperature information and threshold values associated with each arrival time. When an arrival time signal is input from the temperature information detection unit 33, the threshold setting unit 34 reads a threshold corresponding to the arrival time from the memory 35 and sets this threshold as a threshold of the comparison unit 37.

  Therefore, the comparison unit 37 serving as a determination unit is a so-called comparator, and compares the threshold set by the threshold setting unit 34 with the reflected signal amplified by the amplification unit 36 and outputs a binarized signal. For example, “1” is output when the voltage of the amplified reflected signal is equal to or higher than the threshold voltage, and “0” is output when the voltage of the amplified reflected signal is smaller than the threshold voltage.

  Here, as described above, when transmitting an ultrasonic wave (transmission wave), the driving vibration of the transmitting element 21 is transmitted to the bumper 50, and the vibration of the bumper 50 is transmitted to the outside of the vehicle as a transmission wave. In addition, when the reflected wave of the transmission wave reflected by the obstacle 70 is received, the bumper 50 vibrates by the reflected wave, and this vibration is transmitted to the receiving element 22 and the vibration is converted into an electric signal. That is, when the obstacle 70 is detected, since the bumper 50 is used as a vibration transmission path during transmission and reception, the reflected signal is affected by the physical property (Young's modulus) of the resin of the bumper 50 that varies depending on the ambient temperature. . For example, as shown in the upper part of FIG. 6, assume that the reflected signal is equal to or higher than the threshold voltage V1 at the ambient temperature T1. In this case, “1” is output as the binarized signal. For example, when the ambient temperature changes from T1 to T2 higher than T1, the Young's modulus E decreases and the resin becomes soft, so that the signal level of the reflected signal decreases and the threshold voltage as shown in the middle stage of FIG. It becomes smaller than V1. In this case, “0” is output as the binarized signal. On the other hand, in this embodiment, a threshold value is appropriately set according to the arrival time, that is, the ambient temperature. Therefore, when the ambient temperature reaches T2, V2 lower than V1 is newly set as the threshold voltage. Therefore, even if the signal level of the reflected signal decreases, the reflected signal becomes equal to or higher than the threshold voltage V2, and is used as a binarized signal. “1” is output.

  Then, a determination unit 38 that constitutes a determination unit together with the comparison unit 37 determines the presence or absence of an obstacle 70 based on the binarized signal output from the comparison unit 37. Specifically, when the binarized signal is “1”, there is an obstacle, and when the binarized signal is “0”, it is determined that there is no obstacle. In this way, the presence or absence of the obstacle 70 is determined. And the determination part 38 outputs the determination result to alerting | reporting parts, such as a display apparatus which is not shown in figure, and various actuators.

  As described above, in the obstacle detection device 1 according to the present embodiment, the receiving element 22 (ultrasonic sensor 12) attached to a position different from the transmitting element 21 (ultrasonic sensor 11) on the inner surface 51 of the bumper 50 is used. It is possible to detect the propagation vibration of the bumper 50 that is caused by the transmission of the ultrasonic wave by the transmitting element 21 and the vibration changes according to the ambient temperature. In addition, the reception signal determination unit 32 can detect a propagation signal and a reflection signal among the reception signals of the reception element 22. Further, based on the propagation signal reflecting the ambient temperature, the temperature information detection unit 33 can detect temperature information (arrival time) that varies depending on the ambient temperature. Further, the threshold value used for comparison with the reflected signal amplified by the comparison unit 37 can be set by the threshold value setting unit 34 and the memory 35 in accordance with the temperature information. That is, the threshold value used for determining the presence or absence of an obstacle can be set as appropriate according to the ambient temperature. Therefore, while the obstacle detection device 1 uses the resin bumper 50 whose physical properties change according to the ambient temperature as a vibration transmission path, the physical property change of the bumper 50 due to the change in the ambient temperature is corrected, and the obstacle 70 is corrected. It is possible to accurately detect the presence or absence.

  Further, in the present embodiment, the ultrasonic sensor 11 including the transmitting element 21 transmits an ultrasonic wave to the outside of the vehicle via the bumper 50, and the ultrasonic sensor 12 including the receiving element 22 is obstructed via the bumper 50. A reflected wave from the object 70 is received. That is, the ultrasonic sensors 11 and 12 cannot be seen from the outside of the vehicle. Thereby, the designability is improved.

  In the present embodiment, an example is shown in which the memory 35 stores a correspondence table of temperature information and threshold values associated with the temperature information. However, for example, an arithmetic expression obtained empirically is stored in the memory 35, and the threshold value setting unit 34 may calculate a predetermined threshold value from the input temperature information and the arithmetic expression and set it in the comparison unit 37. good.

  In the present embodiment, an example in which not only a propagation signal but also a reflection signal is obtained from the detection signal of the receiving element 22 has been described. However, the receiving element 22 may be a receiving element for propagation vibration, and a receiving element as receiving means may be provided separately from the element 22.

  For example, in the example illustrated in FIG. 7, the sensor unit includes the ultrasonic sensor 11 including the transmitting / receiving element 23 and the ultrasonic sensor 12 including the receiving element 22. The reception signal determination unit 32 detects only the propagation signal among the detection signals of the reception element 22. In addition, the transmitting / receiving element 23 transmits ultrasonic waves to the outside of the vehicle and also detects reflected waves from the obstacle 70. This transmitting / receiving element 23 does not detect propagation vibration because one element serves as both transmitting means and receiving means. Therefore, the reception signal determination unit 32 such as the reception element 22 is not required, and the reception signal of the transmission / reception combined element 23 is amplified by the amplification unit 36 as a reflected signal.

  In the example shown in FIG. 8, the transmitting / receiving element 23 shown in FIG. 7 is divided into a transmitting element 21 and a receiving element 24. In other words, the sensor unit includes the ultrasonic sensor 11 including the transmitting element 21, the ultrasonic sensor 12 including the receiving element 22, and the ultrasonic sensor 13 including the receiving element 24. The reception signal determination unit 32 detects only the propagation signal among the detection signals of the reception element 22. Of the detection signals of the receiving element 24, the reception signal determination unit 39 detects only the reflected signal. The reception signal determination unit 39 has the same basic configuration as the reception signal determination unit 32, and detects only the reflected signal based on the arrival time and amplitude. The detected reflected signal is amplified by the amplifying unit 36. 7 and 8 are block diagrams showing modifications.

(Second Embodiment)
Next, a second embodiment of the present invention will be described based on FIG. FIG. 9 is a block diagram illustrating a schematic configuration of the obstacle detection apparatus according to the present embodiment.

  Since the obstacle detection device according to the second embodiment is often in common with that according to the first embodiment, the detailed description of the common parts will be omitted below, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, an example in which the threshold value of the comparison unit 37 is appropriately set based on the temperature information detected by the temperature information detection unit 33 has been described. On the other hand, the present embodiment is characterized in that, as shown in FIG. 9, for example, the gain of the amplifying unit 36 is appropriately set based on the temperature information detected by the temperature information detecting unit 33. To do.

  As described above, when the obstacle 70 is detected, the bumper 50 is used as a vibration transmission path at the time of transmission and reception. Therefore, the amplitude of the reflected signal varies depending on the ambient temperature. ) Will be affected. In the present embodiment, the gain of the amplifying unit 36 is set according to the amplitude of the reflected signal, that is, the ambient temperature. The other points are the same as the configuration shown in the first embodiment.

  Also in the example illustrated in FIG. 9, the obstacle detection apparatus 1 includes the ultrasonic sensor 11 including the transmission element 21 and the ultrasonic sensor 12 including the reception element 22 as sensor units. The reception signal determination unit 32 detects the propagation signal and the reception signal from the reception signal of the reception element 22. Moreover, the temperature information detection part 33 detects the temperature information which changes with ambient temperature, such as the amplitude, arrival time, and phase difference of a propagation signal based on a propagation signal. In the present embodiment, the gain setting unit 40 as a gain setting unit sets a predetermined gain corresponding to the temperature information in the amplification unit 36. In the present embodiment, the memory 35 stores in advance a correspondence table between arrival times as temperature information and gains associated with each arrival time. When the arrival time signal is input from the temperature information detection unit 33, the gain setting unit 40 reads the gain corresponding to the arrival time from the memory 35 and sets this gain as the gain of the amplification unit 36. Then, the reflected signal is amplified by the amplifying unit 36 set with a predetermined gain, compared with the threshold value by the comparing unit 37, and then the presence or absence of the obstacle 70 is determined by the determining unit 38 based on the comparison result. It has come to be.

  As described above, also in the obstacle detection device 1 according to the present embodiment, the receiving element 22 (ultrasonic sensor 12) attached to the inner surface 51 of the bumper 50 at a position different from the transmitting element 21 (ultrasonic sensor 11). It is possible to detect the propagation vibration of the bumper 50 that is caused by the transmission of the ultrasonic wave by the transmitting element 21 and the vibration changes according to the ambient temperature. In addition, the reception signal determination unit 32 can detect a propagation signal and a reflection signal among the reception signals of the reception element 22. Further, based on the propagation signal reflecting the ambient temperature, the temperature information detection unit 33 can detect temperature information (arrival time) that varies depending on the ambient temperature. Then, the gain of the amplifying unit 36 can be appropriately set by the gain setting unit 40 and the memory 35 according to the temperature information. Therefore, while the obstacle detection device 1 uses the resin bumper 50 whose physical properties change according to the ambient temperature as a vibration transmission path, the physical property change of the bumper 50 due to the change in the ambient temperature is corrected, and the obstacle 70 is corrected. It is possible to accurately detect the presence or absence.

  Also in this embodiment, the ultrasonic sensor 11 including the transmitting element 21 transmits an ultrasonic wave to the outside of the vehicle via the bumper 50, and the ultrasonic sensor 12 including the receiving element 22 fails through the bumper 50. A reflected wave from the object 70 is received. Thereby, the designability is improved.

  Also in the present embodiment, an example is shown in which the memory 35 stores a correspondence table of temperature information and gains associated with the temperature information. However, for example, an empirically obtained arithmetic expression is stored in the memory 35, and the gain setting unit 40 calculates a predetermined gain from the input temperature information and the arithmetic expression and sets the gain in the amplifying unit 36. good.

  Also in this embodiment, the obstacle detection apparatus 1 has shown an example having the ultrasonic sensor 11 including the transmitting element 21 and the ultrasonic sensor 12 including the receiving element 22 as the sensor unit. However, the characteristic part shown in this embodiment can be applied to the modification shown in the first embodiment (see FIGS. 7 and 8).

(Third embodiment)
Next, 2nd Embodiment of this invention is described based on FIG. FIG. 10 is a block diagram illustrating a schematic configuration of the obstacle detection apparatus according to the present embodiment.

  Since the obstacle detection apparatus according to the third embodiment is common in common with that according to the first embodiment, detailed description of the common parts will be omitted, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown to said each embodiment.

  In the first embodiment, an example in which the threshold value of the comparison unit 37 is appropriately set based on the temperature information detected by the temperature information detection unit 33 has been described. In the second embodiment, an example in which the gain of the amplifying unit 36 is appropriately set based on the temperature information detected by the temperature information detecting unit 33 has been described. That is, the example which correct | amends after reception of a reflected wave was shown. On the other hand, the present embodiment is characterized in that the drive signal is appropriately set based on the temperature information detected by the temperature information detection unit 33, for example, as shown in FIG. That is, the correction is performed before transmission of the transmission wave.

  Also in the example illustrated in FIG. 10, the obstacle detection apparatus 1 includes the ultrasonic sensor 11 including the transmission element 21 and the ultrasonic sensor 12 including the reception element 22 as sensor units. The reception signal determination unit 32 detects the propagation signal and the reception signal from the reception signal of the reception element 22. Moreover, the temperature information detection part 33 detects the temperature information which changes with ambient temperature, such as the amplitude, arrival time, and phase difference of a propagation signal based on a propagation signal. And in this embodiment, the drive signal setting part 41 as a drive signal setting means sets at least one of the voltage of a drive signal, the number of pulses, and a frequency to a predetermined value according to temperature information. In the present embodiment, the memory 35 stores in advance a correspondence table between arrival times as temperature information and driving signal voltages associated with each arrival time. When the arrival time signal is input from the temperature information detection unit 33, the drive signal setting unit 41 reads the voltage of the drive signal corresponding to the arrival time from the memory 35, and generates the voltage by the drive signal generation unit 31. Set as signal voltage. The drive signal generation unit 31 generates a drive signal having a set voltage, and the transmission element 21 to which this signal is applied vibrates and transmits ultrasonic waves to the outside of the vehicle via the bumper 50. Then, the receiving element 22 receives the reflected wave from the obstacle 70 via the bumper 50, the reflected signal detected by the received signal determining unit 32 is amplified by the amplifying unit 36, and the threshold value is detected by the comparing unit 37. After the comparison, the presence or absence of the obstacle 70 is determined by the determination unit 38 based on the comparison result.

  As described above, also in the obstacle detection device 1 according to the present embodiment, the receiving element 22 (ultrasonic sensor 12) attached to the inner surface 51 of the bumper 50 at a position different from the transmitting element 21 (ultrasonic sensor 11). It is possible to detect the propagation vibration of the bumper 50 that is caused by the transmission of the ultrasonic wave by the transmitting element 21 and the vibration changes according to the ambient temperature. In addition, the reception signal determination unit 32 can detect a propagation signal and a reflection signal among the reception signals of the reception element 22. Further, based on the propagation signal reflecting the ambient temperature, the temperature information detection unit 33 can detect temperature information (arrival time) that varies depending on the ambient temperature. The drive signal setting can be adjusted by the drive signal setting unit 41 and the memory 35 in accordance with the temperature information. Therefore, while the obstacle detection device 1 uses the resin bumper 50 whose physical properties change according to the ambient temperature as a vibration transmission path, the physical property change of the bumper 50 due to the change in the ambient temperature is corrected, and the obstacle 70 is corrected. It is possible to accurately detect the presence or absence.

  Also in this embodiment, the ultrasonic sensor 11 including the transmitting element 21 transmits an ultrasonic wave to the outside of the vehicle via the bumper 50, and the ultrasonic sensor 12 including the receiving element 22 fails through the bumper 50. A reflected wave from the object 70 is received. Thereby, the designability is improved.

  Also in the present embodiment, an example is shown in which the memory 35 stores a correspondence table between the temperature information and the voltage of the drive signal associated with the temperature information. However, for example, an arithmetic expression obtained empirically is stored in the memory 35, and the drive signal setting unit 41 calculates a predetermined voltage from the input temperature information and the arithmetic expression, and drives this voltage as the voltage of the drive signal. You may make it set to the signal generation part 31. FIG.

  Also in this embodiment, the obstacle detection apparatus 1 has shown an example having the ultrasonic sensor 11 including the transmitting element 21 and the ultrasonic sensor 12 including the receiving element 22 as the sensor unit. However, the characteristic part shown in this embodiment can be applied to the modification shown in the first embodiment (see FIGS. 7 and 8).

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In this embodiment, the example in which the groove part 52 is provided in the inner surface 51 of the bumper 50 was shown. However, a configuration without the groove 52 may be adopted. Further, the shape of the groove 52 is not limited to the above example. For example, it may be an annular shape or an elliptical shape.

  The example of the bumper 50 was shown as a resin-made wall member in a vehicle. However, for example, a resin member other than the bumper 50 such as a resin molding provided at a corner portion of the bumper 50 may be used as the wall member. Moreover, it is not limited to a vehicle.

It is a block diagram showing a schematic structure of an obstacle detection device concerning a 1st embodiment. FIG. 2 is an internal plan view showing an outline of a structure for attaching an ultrasonic sensor to a bumper in the obstacle detection device shown in FIG. 1. It is sectional drawing which follows the III-III line | wire shown in FIG. It is a timing chart of the received signal by a transmitting element. It is a timing chart of ultrasonic transmission of a transmitting element and propagation vibration reception of a receiving element. It is a figure which shows the relationship between the reflected signal of a transmission element, and a threshold voltage. It is a block diagram which shows a modification. It is a block diagram which shows a modification. It is a block diagram which shows schematic structure of the obstruction detection apparatus which concerns on 2nd Embodiment. It is a block diagram which shows schematic structure of the obstruction detection apparatus which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Obstacle detection apparatus 11, 12 ... Ultrasonic sensor 21 ... Transmitting element 22 ... Receiving element 32 ... Received signal determination part 33 ... Temperature information detection part 34 ... Threshold setting unit 35 ... Memory 37 ... Comparison unit 38 ... Determination unit 50 ... Bumper

Claims (11)

A transmitting means attached to the inner surface of the wall member made of resin, and transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path;
An obstacle detection device comprising: at least one receiving unit that is attached to the inner surface of the wall member, receives ultrasonic waves using the wall member as a vibration transmission path, and outputs a reception signal;
As the receiving means, including a first receiving means attached at a position different from the transmitting means on the inner surface of the wall member,
Propagation detecting means for detecting a first received signal caused by a propagation vibration propagated through the wall member, which is generated along with the ultrasonic transmission of the transmitting means among the received signals of the first receiving means;
Temperature information detecting means for detecting temperature information that varies depending on ambient temperature based on the first received signal;
Threshold setting means for setting a predetermined threshold according to the temperature information;
A determination unit that compares the second reception signal based on the reflected wave of the obstacle detected by the reception unit and the set threshold value, and determines the presence or absence of the obstacle based on the result. Obstacle detection device characterized by.   The obstacle detection apparatus according to claim 1, wherein the threshold value setting unit includes a storage unit that stores a correspondence table between the temperature information and a threshold value associated with the temperature information. A transmitting means attached to the inner surface of the wall member made of resin, and transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path;
An obstacle detection device comprising: at least one receiving unit that is attached to the inner surface of the wall member, receives ultrasonic waves using the wall member as a vibration transmission path, and outputs a reception signal;
As the receiving means, including a first receiving means attached at a position different from the transmitting means on the inner surface of the wall member,
Propagation detecting means for detecting a first received signal caused by a propagation vibration propagated through the wall member, which is generated along with ultrasonic transmission of the transmitting means among the received signals of the first receiving means;
Temperature information detecting means for detecting temperature information that varies depending on ambient temperature based on the first received signal;
Amplifying means for amplifying the second received signal detected by the receiving means and reflected by the obstacle;
Gain setting means for setting the gain of the amplification means according to the temperature information;
An obstacle detection apparatus comprising: a determination unit that compares the second reception signal amplified by the amplification unit with a predetermined threshold and determines the presence or absence of an obstacle based on the result. .   The obstacle detection apparatus according to claim 3, wherein the gain setting means includes storage means for storing a correspondence table of the temperature information and gains associated with the temperature information. A transmitting means attached to the inner surface of the wall member made of resin, and transmitting ultrasonic waves to the outside of the wall member using the wall member as a vibration transmission path;
An obstacle detection device comprising: at least one receiving unit that is attached to the inner surface of the wall member, receives ultrasonic waves using the wall member as a vibration transmission path, and outputs a reception signal;
As the receiving means, including a first receiving means attached at a position different from the transmitting means on the inner surface of the wall member,
Propagation detecting means for detecting a first received signal caused by a propagation vibration propagated through the wall member, which is generated along with the ultrasonic transmission of the transmitting means among the received signals of the first receiving means;
Temperature information detecting means for detecting temperature information that varies depending on ambient temperature based on the first received signal;
Drive signal generation means for generating a drive signal for transmitting ultrasonic waves by the transmission means;
Drive signal setting means for setting at least one of the voltage, the number of pulses, and the frequency of the drive signal according to the temperature information;
A second receiving signal based on the reflected wave of the obstacle detected by the receiving means and a predetermined threshold value, and a judging means for judging the presence or absence of the obstacle based on the result. Obstacle detection device.   The drive signal setting means includes storage means for storing a correspondence table of the temperature information and at least one of the voltage, the number of pulses, and the frequency of the drive signal associated with the temperature information. The obstacle detection device according to claim 5.   7. The propagation detection unit detects the first reception signal based on at least one of an amplitude and an arrival time of a reception signal received by the first reception unit. Obstacle detection device according to.   The obstacle detection device according to claim 1, wherein the temperature information detection unit detects an amplitude of the first reception signal as the temperature information.   The obstacle detection apparatus according to claim 1, wherein the temperature information detection unit detects an arrival time of the first reception signal as the temperature information.   2. The temperature information detection unit detects a phase difference of the first reception signal based on a drive signal applied to the transmission unit as the temperature information. The obstacle detection device according to any one of? 7.   The obstacle detection device according to claim 1, wherein the wall member is a bumper of a vehicle.

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