JP4797463B2 - Collision determination device - Google Patents

Description

  The present invention belongs to the technical field of a collision determination device that determines a collision between an own vehicle and an obstacle outside the vehicle by using an ultrasonic wave, a laser, or the like.

As this type of technology, millimeter waves and ultrasonic waves are transmitted toward the target, the relative speed and distance between the vehicle and the target are calculated, and the vehicle and the object are calculated based on the relative distance and relative speed. A device for determining whether or not a collision with a mark can be avoided is disclosed (for example, see Patent Document 1).
JP 2003-320866 A

  However, in the above prior art, since the relative speed between the subject vehicle and the target that is an object outside the vehicle is measured using the Doppler frequency, when the distance between the subject vehicle and the target is short, the reception intensity of the received signal is low. growing. As a result, the reception intensity may exceed the allowable intensity of the receiver or the like, and a phenomenon in which information near the inflection point of the waveform is lost (hereinafter referred to as a clipping phenomenon) may occur. Therefore, there is a problem that the frequency of the received wave cannot be detected correctly and the relative velocity cannot be calculated accurately.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a collision determination device capable of correctly determining whether or not the own vehicle and an object outside the vehicle collide. is there.

In order to achieve the above object, in the present invention, a transmitter for transmitting a transmission wave to an object outside the vehicle, transmission power setting means for setting a transmission power transmitted by the transmitter, and the object from the object outside the vehicle A receiver for receiving a reflected wave with respect to a transmission wave; a transmission / reception time calculating means for calculating a transmission / reception time from when the transmitter transmits a transmission wave until the receiver receives the reflected wave; and Distance calculating means for calculating a distance between the own vehicle and the object outside the vehicle, estimating a center of amplitude of the waveform of the reflected wave, calculating a frequency from a period of the reflected wave at the center of the amplitude, and transmitting the transmission A relative speed calculation means for calculating a relative speed between the vehicle and the object outside the vehicle using a frequency of the wave and a frequency of the reflected wave; the distance between the vehicle and the object outside the vehicle; and the relative speed Based on the own vehicle In the collision determining apparatus and a collision determining means for performing collision judgment with the outside object, the received power detecting means for detecting the reception power of the reflected wave, the harmonic of the reflected wave with respect to the frequency of the transmission wave the percentage in which distortion of the component, and the integral value of the reflected wave, from the two signals, the type discrimination means for discriminating the type of the outside object,
The transmission power setting means sets the transmission power based on the type of the object outside the vehicle determined by the type determination means, and the transmission power of the transmission wave increases as the reception power of the reflected wave increases. Was made smaller.

  In the occupant protection device of the present invention, the transmission power of the transmission wave is reduced as the reception power of the reflected wave increases. Therefore, the reception power can be reduced, and the reflected waveform clipping phenomenon can be avoided on the receiver side. In addition, it is possible to correctly detect the frequency of the received reflected wave, and by correctly calculating the relative speed between the vehicle and the object outside the vehicle, it is possible to correctly determine the collision between the vehicle and the object outside the vehicle.

  Hereinafter, the best mode for realizing the collision determination device of the present invention will be described based on Examples 1 to 5.

  First, the configuration will be described.

  FIG. 1 is a diagram showing a configuration of an occupant protection device 1 equipped with a collision determination device of the present invention. The occupant protection device 1 is connected to an ultrasonic sensor (transmitter, receiver) 10 that transmits and receives ultrasonic waves, a controller 20 that processes information from the ultrasonic sensor 10, and the controller 20, and protects occupants during a collision. And an occupant restraint device 30. The occupant restraint device 30 includes, for example, an airbag, a seat belt, a seat, a headrest, and the like.

  The ultrasonic sensor 10 transmits the ultrasonic wave to the outside of the vehicle and also receives the reflected wave that is reflected by the object outside the vehicle and returned from the transmitted ultrasonic wave. Here, the object outside the vehicle is, for example, a newspaper or the like (hereinafter referred to as a low-damaged obstacle) having low harm to the passengers of the own vehicle even if it collides with a soft and small own vehicle in front or rear of the vehicle, or When the vehicle collides with a hard vehicle such as a car or a wall, it is an obstacle that is highly harmful to the passenger of the vehicle. FIG. 2 is a vehicle rear view showing an installation state of the ultrasonic sensor 10. In FIG. 2, the ultrasonic sensor 10 is attached to the rear side surface of the vehicle body 100. Specifically, the ultrasonic sensor 10 is provided near the center of the bumper fascia 101.

  Returning to FIG. 1, the controller 20 will be described. The controller 20 controls the ultrasonic sensor 10 and the occupant restraint device 30. The controller 20 transmits / receives a signal to / from the ultrasonic sensor 10, an operation signal output unit 22 that outputs an operation signal to the occupant restraint device 30, and the ultrasonic sensor 10 and the occupant restraint device 30. CPU 23 for calculating a control signal to the CPU, and a RAM 24 and a ROM 25 for storing information necessary for the calculation of the CPU 23.

  The input / output unit 21 includes, for example, an electronic device having a general A / D conversion function and a communication port that can receive a digital signal.

  The CPU 23 has a transmission / reception command function, a collision detection function, a type determination function, and a constraint determination function.

  The transmission / reception command function of the CPU 23 is a function for instructing the ultrasonic sensor 10 to transmit and receive ultrasonic waves. For this reason, the ultrasonic sensor 10 is configured to transmit and receive ultrasonic waves based on a command from the CPU 23.

  The collision detection function of the CPU 23 is a function for obtaining a distance, relative speed, and the like between the host vehicle and the object outside the vehicle and detecting whether the host vehicle collides with the object outside the vehicle in the future. When the possibility of a collision is detected, the CPU 23 determines the type of the object outside the vehicle by the type determination function described below.

  The type discrimination function of the CPU 23 is a function for discriminating the type of the object outside the vehicle from the waveform of the reflected wave received by the ultrasonic sensor 10. The type discrimination function may discriminate the type of the object outside the vehicle from elements other than the integrated value and distortion of the waveform of the reflected wave.

  The restraint judgment function of the CPU 23 is a function for judging whether or not the occupant should be restrained according to the type of the object outside the vehicle determined by the type determination function. Specifically, when the type of the object outside the vehicle determined by the type determination function is a vehicle or a wall, the restraint judgment function of the CPU 23 is considered to have a large impact at the time of collision, so it is judged that the passenger should be restrained and protected. . On the other hand, if the type of the object outside the vehicle determined by the type determination function is not a vehicle or a wall, the constraint determination function of the CPU 23 determines that there is no need to restrain and protect the occupant because the impact at the time of collision is considered to be relatively small. .

  The ROM 25 stores a program corresponding to each function of the CPU 23. For this reason, when the vehicle is turned on, the CPU 23 reads a program from the ROM 25 and executes each function.

  The operation signal output unit 22 is configured to output an operation signal from the CPU 23 to the occupant restraint device 30 when it is determined that the occupant should be restrained and protected by the restraint judgment function of the CPU 23.

  The occupant restraint device 30 is actuated by receiving an actuation signal to restrain the occupant. The occupant restraint device 30 includes restraint means such as an airbag, a seat belt, a seat, and a headrest, and is configured to restrain the occupant at the time of collision prediction. The occupant restraint device 30 may be a device that moves parts such as the vehicle body 100 in order to absorb an impact caused by a collision, or may be a device that changes the shock absorption characteristics of the parts such as the vehicle body 100. .

  Moreover, you may make it share the controller 20 with the controller used for the existing airbag and seatbelt apparatus. Further, the controller 20 is connected to an obstacle detection device for notifying the driver of the distance to the object outside the vehicle and the position information of the object outside the vehicle, a presentation device for notifying the distance information through a display unit or an alarm device, and the like. You may do it. Further, the ultrasonic sensor 10 is commonly used with a back sonar that detects the distance between the obstacle behind the vehicle by ultrasonic waves and a corner sonar that detects an object outside the vehicle within a predetermined distance from the corner by using ultrasonic waves. You may do it.

  Next, the operation will be described.

[Collision determination control processing]
FIG. 3 is a flowchart showing the flow of processing performed in the controller 20.

  In step S1, the transmission power of the ultrasonic wave to be transmitted is set. In the first cycle immediately after the start of the system, the transmission power is determined by the initial value stored in the controller 20 in advance.

  In step S2, an ultrasonic wave is transmitted. When the transmission is completed, the process proceeds to step S3, and reception of the reflected ultrasonic wave transmitted in step S2 is started.

  In step S3, the received power (amplitude) of the received reflected wave is amplified by an amplifier (not shown), and the received power information is output to each device. This step S3 corresponds to the reception power detection means of the present invention.

  In step S4, the distance, relative speed, and relative acceleration between the vehicle and the object outside the vehicle are calculated. The distance is calculated from the transmission / reception time by obtaining the time (hereinafter referred to as transmission / reception time) from when the ultrasonic sensor 10 transmits the ultrasonic wave until receiving the reflected wave. The relative speed is calculated from the Doppler frequency of the transmission wave frequency and the reflected wave frequency, and the relative speed calculated from the reflected wave received in the previous cycle and the relative speed calculated from the reflected wave received in the current cycle are The relative acceleration is obtained from the change in. This step S4 corresponds to the transmission / reception time calculation means, distance calculation means, relative speed calculation means, and relative acceleration calculation means of the present invention.

In step S5, it is determined whether or not the collision between the own vehicle and the object outside the vehicle is performed, and it is determined whether or not the collision occupant restraint device 30 is to be operated. If so, the process proceeds to step S9. Collision determination in step S 5 corresponds to the collision determination unit of the present invention.

  In step S6, it is determined whether the type of object outside the vehicle is a low-damaging obstacle, a wall, or a vehicle, and the process proceeds to step S7.

  In step S7, it is determined whether or not the type of the object outside the vehicle determined in step S6 is a car or a wall. If the object is a car or a wall, the process proceeds to step S8. Migrate to

  In step S8, since it is a scene where occupant protection is required, an operation is commanded to the occupant restraint device 30.

  In step S9, the distance between the own vehicle and the object outside the vehicle when the transmission wave to be transmitted next is reflected by the object outside the vehicle is predicted, and the process proceeds to step S10.

  In step S10, the transmission power to be transmitted next time is determined according to the distance between the vehicle and the object outside the vehicle predicted in step S9, and the process returns to step S1. This step S10 corresponds to the transmission power setting means of the present invention.

[Transmission power setting control action]
Next, transmission power setting means, which is a main component of the present invention, will be described in detail.

  In the present embodiment, the distance and relative speed between the host vehicle and the object outside the vehicle are obtained, and it is determined whether or not to operate the occupant restraint device 30 based on the distance and relative speed. The relative speed between the subject vehicle and the object outside the vehicle is calculated from the change between the frequency of the transmitted wave and the frequency of the reflected wave.

  When using the above judgment, if the distance between the vehicle and the object outside the vehicle is short or the amplitude of the transmitted wave is large, the clipped phenomenon occurs in the waveform after the received reflected wave is amplified by an amplifier (not shown). To do. As shown in FIG. 4, the clip phenomenon indicates a phenomenon in which the profile before amplification cannot be reproduced near the inflection point of the amplitude. FIG. 5 is a partially enlarged view of the waveform shown in FIG. 4 in the time axis direction. Since the vicinity of the inflection point of the received reflected wave is clipped and the inflection point of the correct amplitude cannot be estimated, the position of the center of the amplitude cannot be estimated accurately.

  Therefore, the position of the time axis different from the true amplitude center indicated by the alternate long and short dash line in FIG. 5 is estimated as the center of the amplitude, and the observed frequency is the time of the half cycle of the waveform as shown in FIG. Are two types of time that differ every half cycle. Two types of high frequency and low frequency are calculated according to these two types of 1/2 cycle time. This phenomenon means that two types of relative speeds are calculated, and the calculated relative speed varies. Occurs. Due to the above-mentioned causes, if the reflected wave waveform after amplification is clipped, it is impossible to measure an accurate relative velocity.

  Therefore, in this embodiment, the transmission power of the transmission wave to be transmitted is variably controlled so that the reflected wave waveform is not clipped. The transmission power and reception power are determined by the amplitude and frequency of the transmission wave and reception wave.

  In this embodiment, since the relative speed between the vehicle and the object outside the vehicle is calculated based on the frequency change, the transmission power is controlled by the magnitude of the amplitude of the transmission wave with the frequency of the transmission wave and the reception wave fixed. ing. Therefore, hereinafter, the magnitudes of the transmission power and the reception power indicate the magnitudes of the amplitudes of the transmission wave and the reception wave.

  Further, in this embodiment, the distance between the own vehicle and the object outside the vehicle when the transmission wave to be transmitted is reflected by the object outside the vehicle is estimated. That is, the power of the transmission wave, that is, the amplitude of the transmission wave is controlled so that the waveform of the reflected wave after amplification is not clipped according to this distance.

  In this embodiment, the transmission power setting means corresponds to step S10 of FIG. Hereinafter, the process performed in step S10 will be described in detail.

The controller 20 has a distance-power diagram as shown in FIG. 7 in advance. The transmission power S shown in FIG. 7 indicates a value at which the waveform of the reflected wave after amplification does not clip according to the distance between the host vehicle and the object outside the vehicle. In Figure 7, the distance between the vehicle and the outside object is proportional to the transmission and reception time, and the horizontal axis indicates transmission and reception time t _d.

The distance between the vehicle and the object outside the vehicle at this time indicates the predicted distance L [0] between the vehicle and the object outside the vehicle when the transmission wave to be transmitted next is reflected on the object outside the vehicle, and the transmission / reception time t _d [ 0] is a transmission / reception time when the distance between the vehicle and the object outside the vehicle is L [0]. Calculation of the predicted distance L [0] between the vehicle and the object outside the vehicle will be described later.

ここで、S₀は超音波センサの受信回路に一般的に用いる増幅器の特性に依存して決定する定数である。送信パワーは時間の4乗に比例する関数とする事が好ましい。これは、波は伝播する距離の4乗に比例して減衰する原理に基づくものである。ただし、図７に示す距離―パワー線図は、超音波センサ１０の特性や周辺回路の特性によって変更する事も可能である。この距離―パワー線図は自車と車外対象物との距離に応じて、増幅器を通過した後の反射波の波形がクリップしてしまい、初期の波形形状と異なる形状とならない上限の値を反射波として受信するに設定する事が肝要である。 Transmission power to next transmission S is determined by the transmitting and receiving time t _d by the equation (1) below.

Here, S ₀ is a constant determined depending on the characteristics of an amplifier generally used in the receiving circuit of the ultrasonic sensor. The transmission power is preferably a function proportional to the fourth power of time. This is based on the principle that waves are attenuated in proportion to the fourth power of the propagation distance. However, the distance-power diagram shown in FIG. 7 can be changed according to the characteristics of the ultrasonic sensor 10 and the characteristics of the peripheral circuits. In this distance-power diagram, the waveform of the reflected wave after passing through the amplifier is clipped according to the distance between the vehicle and the object outside the vehicle, and the upper limit value that does not differ from the initial waveform shape is reflected. It is important to set to receive as a wave.

  In the above, a distance-power diagram as shown in FIG. 7 is used in which the distance between the vehicle and the object outside the vehicle is predicted and the transmission power corresponding to the transmission / reception time at that distance is determined. Using the reception power-transmission power diagram that decreases the transmission power of the transmission wave to be transmitted next time as the reception power of the reception wave received last time increases, the transmission power corresponding to the reception power is determined. You may do it.

  With the above operation, the transmission power of the transmission wave to be transmitted is variably controlled so that the reflected wave waveform is not clipped, so that the frequency can be accurately detected, and the relative speed between the vehicle and the object outside the vehicle can be further increased. It can be determined accurately.

[Distance / Relative speed calculation]
A method for calculating the distance and relative speed between the vehicle and the object outside the vehicle performed in step S4 of FIG. 3 in the controller 20 will be described.

ここで、cは音速を示す。 FIG. 8 is a diagram for explaining a transmission / reception time t _d from when the ultrasonic sensor 10 transmits an ultrasonic wave to when it receives the ultrasonic wave. The distance L between the vehicle and the outside object, based on the reception time t _d is calculated based on the equation (2).

Here, c indicates the speed of sound.

  FIG. 9 is a diagram illustrating the reflected wave received by the ultrasonic sensor 10.

周波数fを用いて、次の式（４）により相対速度Vを算出する。

ここで、f_dはドップラ周波数である。このドップラ周波数とは、送信波の周波数と反射波の周波数との差である。 In order to calculate the relative speed between the vehicle and the object outside the vehicle, the center of the amplitude (time axis in FIG. 9) is obtained from the inflection point of the amplitude of the reflected wave. The time when the reflected wave intersects the time axis is calculated, and the time of the half period of the reflected wave is calculated. The value of this 1/2 period is doubled to obtain a period T, and the frequency f is calculated from the following equation (3).

The relative speed V is calculated by the following formula (4) using the frequency f.

Here, f _d is a Doppler frequency. This Doppler frequency is the difference between the frequency of the transmitted wave and the frequency of the reflected wave.

[Predicted distance calculation]
Next, a method of predicting the distance between the own vehicle and the object outside the vehicle when the transmission wave to be transmitted next time is reflected on the object outside the vehicle, performed in step S9 of FIG. 3 in the controller 20 will be described.

ここでt_d[-1]は、前回の送受信時間である。 The distance L [-1] and the relative speed V [-1] between the own vehicle and the object outside the vehicle are calculated from the reflected wave received last time from the equations (2) and (4). Further, the relative acceleration a is calculated from the relative velocity V [-2] between the own vehicle and the object outside the vehicle calculated from the reflected wave received last time. Therefore, the distance L [0] between the own vehicle and the object outside the vehicle when the transmission wave to be transmitted next is reflected by the object outside the vehicle is calculated by the following equation (5).

Here, t _d [−1] is the previous transmission / reception time.

[Restriction judgment]
Next, a method for determining whether or not to operate the occupant restraint device 30 performed in step S5 of FIG. 3 in the controller 20 will be described.

ここで、vは自車と車外対象物との相対速度、gは緊急制動時の減速度を示す。 The determination as to whether or not to operate the occupant restraint device 30 may be performed using a conventional method. For example, when the relative distance D between the vehicle and the object outside the vehicle calculated by the CPU 23 satisfies the condition of the following equation (6), it is determined that the occupant restraint device 30 is activated.

Here, v represents the relative speed between the vehicle and the object outside the vehicle, and g represents the deceleration during emergency braking.

なお、本実施例では式（６）及び式（７）を共に満たした場合、乗員拘束装置３０を作動させると判断するようにしたが、いずれか１つの条件を用いて判断しても良いし、他の条件も考慮して３つ以上の条件を用いて判断しても良い。 As another example, assuming that the time required for the occupant restraint device 30 to operate to a sufficient extent is t _m , the occupant restraint is satisfied when the condition of the following equation (7) is satisfied. It is determined that the device 30 is activated.

In the present embodiment, it is determined that the occupant restraint device 30 is operated when both the expressions (6) and (7) are satisfied. However, the determination may be made using any one of the conditions. The determination may be made using three or more conditions in consideration of other conditions.

[Type discrimination]
Next, a method for determining the type of the object outside the vehicle performed in step S6 of FIG. 3 in the controller 20 will be described.

(Time integration of reflected wave)
10A and 10B are diagrams showing calculation of the envelope. FIG. 10A shows a state before the envelope process, and FIG. 10B shows a state after the envelope process. Since the ultrasonic sensor 10 transmits a transmission wave over several wavelengths as well as one wavelength, the reflected wave is similarly received over several wavelengths as shown in FIG. The controller 20 detects a peak point for each wavelength of the received reflected waves of several wavelengths, and obtains a waveform shown in FIG. 10B by connecting the peak points. In the following description, a smooth waveform after the reflected wave is enveloped as shown in FIG. 10B is referred to as an envelope.

ここで、y(t)はエンベロープを数化したものであり、時間0は反射波を受信し始めた時間であり、時間t1反射波を受信し終えた時間である。式（８）により反射波の受信パワーを計算する。 After the envelope process, the controller 20 calculates a time integral value of the envelope by the following equation (8). Specifically, the CPU 23 obtains a time integral value by the following calculation formula.

Here, y (t) is a numerical value of the envelope, and time 0 is a time when the reflected wave starts to be received, and a time when the time t1 reflected wave is received. The received power of the reflected wave is calculated according to equation (8).

  FIG. 11 is a diagram illustrating an envelope of a reflected wave for each object outside the vehicle. FIG. 11A shows a waveform before the envelope process when the object outside the vehicle is a car, and FIG. 11B shows a waveform after the envelope process when the object outside the car is a car. Further, (c) shows a waveform before envelope processing when the object outside the vehicle is a low-damage obstacle, and (d) shows a waveform after envelope processing when the object outside the vehicle is a low-damage obstacle. Show. (E) shows the waveform before envelope processing when the object outside the vehicle is a wall, and (f) shows the waveform after envelope processing when the object outside the vehicle is a wall. FIG. 12 is an explanatory diagram showing the correlation between the integral value of the envelope for each object outside the vehicle and time.

  As shown in FIGS. 11A and 11B, when the object outside the vehicle is a car, the intensity of the reflected wave tends to continue for a long time in a relatively strong state. This is because waves from a plurality of reflection points in the depth direction overlap each other in the case of an object with a depth such as a vehicle. For this reason, the integral value of the envelope waveform when the object outside the vehicle shown by the solid line in FIG. 12 is a car shows a high value.

  On the other hand, when the object outside the vehicle is a low-damaging obstacle such as a newspaper or a wall, as shown in FIGS. 11 (c), (d), (e), (f), the intensity of the reflected wave is There is a tendency that a strong state is difficult to continue. This is because there is little depth and there is almost no overlapping of waves from the reflection point. For this reason, when the vehicle exterior object shown by the dotted line in FIG. 12 is a low-damaging obstacle, and the integration value of the envelope waveform when the vehicle exterior object shown by the alternate long and short dash line is a wall is shown, It shows a lower value than when it is a car.

(Strain rate)
When the object outside the vehicle is a car as shown in FIG. 12, the time integral value of the envelope is significantly different from other low-damaging obstacles and walls, so that the vehicle can be identified using the time integral value of the envelope. . On the other hand, the time integral value of the envelope when the object outside the vehicle is a low-damage obstacle is close to the time integral value of the envelope when the object outside the vehicle is a wall. Therefore, the distortion rate of the waveform of the reflected wave is used in order to reliably discriminate between the low-damaging obstacle and the wall.

  For example, if the frequency of the transmitted wave (fundamental frequency) is 50 [kHz], it has been received if it has a relative speed between the vehicle and the object outside the vehicle with respect to the frequency component of 50 [kHz]. The reflected wave includes various harmonic components in addition to the Doppler shifted fundamental frequency generated by the Doppler effect. In particular, the reflected wave signal includes a harmonic component of a sine wave called a distortion component due to the reflectance of the object outside the vehicle and the effect of clipping by an amplifier in the receiving circuit.

  FIG. 13 is a diagram illustrating a waveform of a reflected wave for each object outside the vehicle and a distortion factor of the waveform of the reflected wave. As shown in FIG. 13, the distortion of the waveform of the received reflected wave varies depending on whether the object outside the vehicle is a low-damaging obstacle, a car, or a wall. Specifically, a reflected wave from an object outside the vehicle having a high reflectance such as a wall has a strong reception power. For this reason, for example, the signal waveform after passing through the amplifier of the receiving circuit exceeds the input / output upper limit value of the amplifier, and a value equal to or higher than the upper limit value is cut. Therefore, as shown in the case where the object outside the vehicle in FIG. 13 is a wall, the waveform has a distortion close to a rectangle. On the other hand, the intensity of the reflected wave from an object outside the vehicle whose reflectance is not so large, such as a low-damaging obstacle or a vehicle, is low. For this reason, the value beyond the input / output upper limit value of the amplifier is not cut, and the waveform is assumed to be close to a sine wave as shown in FIG. 13 when the objects outside the vehicle are low-damaging obstacles and vehicles. Become.

  As described above, when the object outside the vehicle is a wall, the distortion becomes large. Here, the magnitude of the distortion can be obtained from the ratio of the harmonic component to the fundamental frequency. That is, the rectangular wave can be reproduced by adding a harmonic component to a certain reference frequency. Further, the shape of the reflected wave becomes rectangular as the ratio of the harmonic component is larger, and becomes closer to a sine wave as the ratio is smaller. For this reason, it is possible to know the degree of distortion (distortion rate) of a waveform in which a value equal to or higher than the upper limit value of the amplifier is cut and has a shape close to a rectangle by obtaining the ratio of the harmonic component to the reference frequency. it can.

ここで、|E₁|は基本周波数（送信周波数）の実効値、|E₂|は第２高調波の実効値、|E_n|は第ｎ高調波（ｎは３以上の整数）の実効値である。 The strain rate is obtained from the following equation (9).

Where | E ₁ | is the effective value of the fundamental frequency (transmission frequency), | E ₂ | is the effective value of the second harmonic, and | E _n | is the effective value of the n-th harmonic (n is an integer of 3 or more). Value.

  Note that waveform distortion may be caused by factors other than clipping. That is, when the object outside the vehicle moves, the reflected wave reflected by the object outside the vehicle has a frequency different from the frequency at the time of transmission due to the Doppler effect. Further, distortion may occur due to a frequency different from the frequency at the time of transmission being combined with the frequency at the time of transmission.

  FIG. 14 is a diagram showing the types of objects to be discriminated from the time integral value of the envelope of the reflected wave and the distortion rate of the waveform. As shown in FIG. 14, when the integral value of the envelope is large, it is determined that the object outside the vehicle is a car. If the integral value of the envelope is small and the distortion rate of the received wave is large, it is determined that the object outside the vehicle is a wall. Further, when the integral value of the envelope is small and the distortion rate of the received wave is small, it is determined that the object outside the vehicle is a low-damaging obstacle. Note that the magnitude of the integral value of the envelope may be determined by providing a threshold value that can reliably determine whether the object outside the vehicle is a vehicle and a low-damaging obstacle or a wall, and distortion of the received wave. The rate determination may be performed by providing a threshold value that can reliably determine whether the object outside the vehicle is a wall or a vehicle or a low-damaging obstacle.

  As described above, the type of the object outside the vehicle is determined, and in the controller 20, it is determined again in step S <b> 7 in FIG. That is, when the object outside the vehicle is a car or a wall, it is determined that the scene is assumed to require occupant protection, and an operation is commanded to the occupant restraint device 30 in step S8.

  FIG. 15 is a diagram showing the relationship between the time integral value of the envelope of the reflected wave and the distortion rate of the waveform, and the operation and non-operation of the occupant restraint device 30. As shown in FIG. 15, when the integral value of the envelope is large, the occupant restraint device 30 is operated. When the integral value of the envelope is small and the distortion rate of the received wave is large, the occupant restraint device 30 is operated. On the other hand, when the integral value of the envelope is small and the distortion rate of the received wave is small, the occupant restraint device 30 is not operated.

[Example of control when an object outside the vehicle approaches]
For example, an example of control performed when an object outside the vehicle is approaching the host vehicle is shown below.

  FIG. 16 is a diagram illustrating transmission power control of a transmission wave according to the distance between the own vehicle and the object outside the vehicle. For example, the current transmission power is set as S2. A transmission wave is transmitted with this transmission power S2, a reflected wave is received, and a distance, a relative speed, and a relative acceleration between the vehicle and the object outside the vehicle are calculated from the received reflected wave. It is determined whether or not to activate the occupant restraint device 30 according to the distance between the host vehicle and the object outside the vehicle, the relative speed, and the relative acceleration. If it is determined that the occupant restraint device 30 is not to be activated, the next transmission wave is calculated from the distance between the vehicle and the object outside the vehicle, the relative speed, and the relative acceleration calculated from the reflected wave of the transmission wave transmitted with the transmission power S2. Predicts the distance between the vehicle and the object outside the vehicle.

For example, if the transmission / reception time t _d 1 at the predicted distance between the vehicle and the object outside the vehicle is t _d 1, the transmission wave transmitted in the next cycle is transmitted at the transmission power S1 corresponding to the distance-power diagram in FIG. . By this action, it is possible to avoid the occurrence of the clipping phenomenon in the waveform after the reflected wave received in the next cycle is amplified by the amplifier.

  Next, the effect will be described.

  (1) The transmission power of the transmission wave is set to be smaller as the reception power of the reflected wave reflected by the object outside the vehicle is increased. Therefore, it is possible to accurately control the transmission power of the reception wave depending on the transmission power of the transmission wave. Therefore, when calculating the speed using the output signal of the non-contact distance sensor such as the ultrasonic sensor 10, the waveform reflected after the received reflected wave is amplified by the amplifier is prevented, and the speed calculation accuracy is improved. be able to.

  (2) The amplitude of the transmitted wave is set to be smaller as the amplitude of the reflected wave reflected from the object outside the vehicle increases. Therefore, it is possible to accurately control the amplitude of the reception wave depending on the amplitude of the transmission wave. Therefore, when calculating the speed using the output signal of the non-contact distance sensor such as the ultrasonic sensor 10, the waveform reflected after the received reflected wave is amplified by the amplifier is prevented, and the speed calculation accuracy is improved. be able to.

(3) The transmission / reception time from when the ultrasonic sensor 10 transmits the transmission wave to the reception of the transmission wave is calculated from the received reflected wave, and the distance between the vehicle and the object outside the vehicle is calculated from the transmission / reception time. calculate. Further, the relative speed between the vehicle and the object outside the vehicle is calculated from the change in the frequency of the transmitted wave and the frequency of the reflected wave, and the relative acceleration between the vehicle and the object outside the vehicle is calculated from the change in the relative speed. The CPU 23 predicts the distance between the vehicle and the object outside the vehicle when the next transmission wave is transmitted from the transmission / reception time calculated above, the distance between the vehicle and the object outside the vehicle, the relative speed, and the relative acceleration. The transmission power of the transmission wave is determined according to the predicted distance. Therefore, the transmission power can be determined in consideration of the attenuation of the reception power of the reflected wave according to the predicted distance.
(4) The reception power of the reflected wave is reduced by setting the transmission power of the transmission wave to be smaller as the reception power of the reflected wave that is reflected back to the object outside the vehicle increases. Therefore, when calculating the speed using the output signal of the non-contact distance sensor such as the ultrasonic sensor 10, the waveform reflected after the received reflected wave is amplified by the amplifier is prevented, and the speed calculation accuracy is improved. be able to.

  Next, Example 2 will be described. Since the operational effects are basically the same as those of the first embodiment, the same components are denoted by the same reference numerals, description thereof is omitted, and only different components are described.

  In the first embodiment, the transmission power is determined according to the distance between the host vehicle and the object outside the vehicle. However, in this embodiment, the transmission power of the transmission wave is further set according to the type of the object outside the vehicle. The point is different.

[Collision determination control processing]
FIG. 17 is a flowchart showing the flow of processing performed in the controller 20 in this embodiment.

  In step S11, the transmission power of the ultrasonic wave to be transmitted is set. In the first cycle immediately after the start of the system, the transmission power is determined by the initial value stored in the controller 20 in advance.

  In step S12, an ultrasonic wave is transmitted. When the transmission is completed, the process proceeds to step S13, and reception of the reflected ultrasonic wave transmitted in step S12 is started.

  In step S13, the received power (amplitude) of the received reflected wave is amplified by an amplifier (not shown), and the received power information is output to each device.

  In step S14, the distance and relative speed between the vehicle and the object outside the vehicle are calculated.

  In step S15, the collision determination between the vehicle and the object outside the vehicle is performed, and it is determined whether or not the occupant restraint device 30 is to be operated. If it is determined to be activated, the process proceeds to step S16 and is determined not to be activated. In this case, the process proceeds to step S19.

  In step S16, it is determined whether the type of the object outside the vehicle is a low-damaging obstacle, a wall, or a vehicle, and the process proceeds to step S17 and step S19. This step S16 corresponds to the type discriminating means of the present invention.

  In step S17, it is determined whether or not the type of the object outside the vehicle determined in step S16 is a car or a wall. If the object is a car or a wall, the process proceeds to step S18. Migrate to

  In step S18, the operation is commanded to the occupant restraint device 30 because the occupant protection is necessary.

  In step S19, the distance between the own vehicle and the object outside the vehicle when the transmission wave to be transmitted next is reflected by the object outside the vehicle is predicted, and the process proceeds to step S20.

  In step S20, the transmission power to be transmitted next time is determined according to the distance between the host vehicle and the object outside the vehicle predicted in step S19 and the type of the object outside the vehicle determined in step S16, and the process returns to step S11.

[Transmission power setting by type]
Next, transmission power setting means according to the present invention, which is a transmission power setting according to the type of the object outside the vehicle, will be described in detail.
Since the reflectance varies depending on the type of the object outside the vehicle, the maximum amplitude of the received reflected wave varies depending on the type of the object outside the vehicle even if the reflected wave is from the object outside the vehicle at the same distance from the own vehicle. Therefore, for example, when transmitting a transmission wave to an object outside the vehicle with a small reflected wave, with the transmission power of the transmission wave set so that the waveform of the reflected wave from the object outside the vehicle where the maximum amplitude of the reflected wave is large is not clipped, There is a possibility that sufficient reflected wave reception power cannot be obtained. On the other hand, if the transmission wave is transmitted to an object outside the vehicle with a large reflected wave with the transmission power of the transmission wave set so that the reflected wave from the object outside the vehicle where the maximum amplitude of the reflected wave is small is not clipped, The waveform may clip.

  Therefore, in this embodiment, the transmission output of the transmission wave is set according to the distance between the own vehicle and the object outside the vehicle and the type of the object outside the vehicle.

  FIG. 18 is a diagram comparing the maximum amplitudes of the reflected waves from the low-damaging obstacle, the car, and the wall at the same distance from the own vehicle. As shown in FIG. 18, the maximum amplitude of the low-damaged obstacle, vehicle, and wall reflected wave is the smallest for the low-damaged obstacle, the largest for the wall, and the low-damaged property for the car. It is larger than an obstacle and smaller than a wall.

  In the controller 20 in advance, a distance-power diagram in the case where the object outside the vehicle indicated by a solid line in FIG. 19 is a low-damaging obstacle, the object outside the vehicle indicated by a one-dot chain line is a vehicle, and the object outside the two-dot chain line is a wall. have. For each of the three distance-power diagrams, the magnitude of power is the highest in the case of a low-damaged obstacle, the power is lowest in the case of a wall, and the case of a low-damaged obstacle is the case of a low-damaged obstacle. It is desirable to set a distance-power diagram as in the case where the object is a car. Similarly to the first embodiment, each power diagram is desirably a function proportional to the distance, that is, the fourth power of the time between transmission and reception. However, in this case as well, as in the first embodiment, it is possible to select an optimum profile as appropriate according to the sensitivity characteristics of the sensor and the characteristics of the circuit.

[Example of control when an object outside the vehicle approaches]
For example, an example of control performed when an object outside the vehicle is approaching the host vehicle is shown below.

  In FIG. 19, for example, the current transmission power is set to S2. A transmission wave is transmitted with this transmission power S2, a reflected wave is received, and a distance, a relative speed, and a relative acceleration between the vehicle and the object outside the vehicle are calculated from the received reflected wave. It is determined whether or not to activate the occupant restraint device 30 according to the distance between the host vehicle and the object outside the vehicle, the relative speed, and the relative acceleration. If it is determined that the occupant restraint device 30 is not to be activated, the next transmission wave is calculated from the distance between the vehicle and the object outside the vehicle, the relative speed, and the relative acceleration calculated from the reflected wave of the transmission wave transmitted with the transmission power S2. Predicts the distance between the vehicle and the object outside the vehicle. Further, the type of the object outside the vehicle is determined from the reflected wave of the transmission wave transmitted with the transmission power S2.

For example, when the transmission / reception time t _d 1 at the predicted distance between the vehicle and the object outside the vehicle is t _d 1, the transmission wave transmitted in the next cycle corresponds to the distance-power diagram in FIG. The transmission power is S1, S1 ', S1 "in the order of low-damaged obstacles, cars, and walls. This action determines the appropriate transmission power according to the type of object outside the vehicle. It is possible to avoid the occurrence of the clipping phenomenon in the waveform after the reflected wave received in the cycle is amplified by the amplifier.

  Next, the effect will be described.

  (5) The controller 20 determines whether the type of the object outside the vehicle is a low-damage obstacle, car, or wall from the time integral value and distortion rate of the reflected wave, and the type of the object outside the vehicle is low-damage The transmission power of the transmission wave was made smaller in the order of obstacles, cars, and walls. Therefore, for reflected waves from walls with high reflectivity, the clipping of the waveform after amplification of the received reflected waves by the amplifier is avoided, and the accuracy of the relative speed between the vehicle and the wall predicted from the reflected waves is avoided. Can be improved. On the other hand, sufficient reflected power can be secured for reflected waves from low-damaged obstacles with low reflectivity, so the relative between the vehicle predicted from reflected waves and the low-damaging obstacles Speed accuracy can be improved. In addition, for the reflected wave from a car whose reflectivity is between low-damaging obstacles and walls, it is possible to ensure sufficient reception power while preventing the waveform clipping phenomenon, It is possible to improve the accuracy of the relative speed between the own vehicle and other vehicles predicted from the reflected wave.

  Next, Example 3 will be described. Since the operational effects are basically the same as those of the second embodiment, the same components are denoted by the same reference numerals, the description thereof is omitted, and only different components are described.

  In the second embodiment, the transmission power is determined according to the distance between the vehicle and the object outside the vehicle and the type of the object outside the vehicle, but in this embodiment, the reflected wave of the reflected wave is transmitted after the ultrasonic sensor 10 transmits the transmission wave. The difference is that a reception waiting time, which is a time waiting for reception, is set.

  The occupant protection device of the present embodiment has the same configuration as that of the second embodiment but is different in operation. Therefore, the same reference numerals are given to the configuration, and the description is omitted.

[Collision determination control processing]
FIG. 20 is a flowchart showing the flow of processing performed in the controller 20 in this embodiment.

  In step S21, the transmission power of the ultrasonic wave to be transmitted is set. In the first cycle immediately after the start of the system, the transmission power is determined by the initial value stored in the controller 20 in advance.

  In step S22, an ultrasonic wave is transmitted. When the transmission is completed, the process proceeds to step S23, and reception of the reflected ultrasonic wave transmitted in step S22 is started.

  In step S23, the received power (amplitude) of the received reflected wave is amplified by an amplifier (not shown), and the received power information is output to each device.

  In step S24, the distance and relative speed between the vehicle and the object outside the vehicle are calculated.

  In step S25, it is determined whether the type of object outside the vehicle is a low-damaging obstacle, a wall, or a car, and the process proceeds to step S26, step S29, and step S30.

  In step S26, it is determined whether or not the occupant restraint device 30 is to be operated. If it is determined that the occupant restraint device 30 is to be operated, the process proceeds to step S27, and if it is determined not to be operated, the process proceeds to step S29.

  In step S27, it is determined whether or not the type of the object outside the vehicle determined in step S16 is a car or a wall. If the object is a car or a wall, the process proceeds to step S28. Migrate to

  In step S28, since it is a scene where occupant protection is required, an operation is commanded to the occupant restraint device 30.

  In step S29, the reception wave waiting time until the highly harmful vehicle or wall (second obstacle) is ignored ignoring the reflected wave from the low harmful obstacle (first obstacle) such as a newspaper with low harm. Set. The processing in step S29 corresponds to the harm determining means and the reception waiting time setting means of the present invention.

  In step S30, the transmission power to be transmitted next time is determined according to the distance between the vehicle and the object outside the vehicle and the type of the object outside the vehicle, and the process returns to step S21.

[Reception standby time setting]
Next, the processing performed in step S29 of FIG. 20 corresponding to the reception standby time setting means of the present invention added in the present embodiment will be described in detail.

  As shown in FIG. 21, in one cycle of distance / velocity measurement, a transmission wave is transmitted and a reception wave is received. Especially in the case of a sensor using ultrasonic waves, the ultrasonic waves are Since the propagation speed of light and radio waves is extremely slow, it takes a relatively long time from transmission to reception. For example, it takes 59 [msec] when the ambient temperature is 0 degree until the object is reflected by the object outside the vehicle at a relative distance of 10 [m]. Vehicles behind with a relative speed of 60 km / h during 59 msec will travel nearly 1 m, and the distance resolution per cycle will be as low as 1 m.

  However, immediately before the collision occurs, increasing the number of measurement cycles and increasing the data density to increase the reliability of the distance / speed data is an important matter for improving the reliability of the occupant protection device 1. It becomes. As described above, in the case of the occupant protection device 1 using an ultrasonic sensor, the time from transmitting an ultrasonic wave to receiving it becomes long, and in particular, the relative distance between the own vehicle and an object outside the vehicle is not known. In some cases, it is necessary to wait for reception after observing the reflected wave. In order to increase the data density by shortening the time of one cycle according to the distance, which is the problem described above, it is important to set the reception standby time to a time at which a reflected wave will be received. is there.

なお、Vsoundは音速、tは現時点での受信待機時間を示す。 On the other hand, in order to shorten the reception waiting time, a reliable collision determination is required when the object outside the vehicle is an object that is assumed to be highly harmful to the host vehicle. For example, in the case of a low-damage obstacle that is not expected to be highly harmful to the vehicle, such as a newspaper on the road, the object outside the vehicle is distant from the vehicle and is present at a longer distance. However, it is important for the protection of the vehicle occupant to receive a reflected wave from an object outside the vehicle that is highly harmful. Therefore, in step S29 in the flowchart of FIG. 20 , a reception standby time to a car or a wall is set. Specifically, as shown in FIG. 22, a current position a distance d3, most outside object that the relative distance is changed to a position a short distance d1 is expected, at step S25 in the flowchart of FIG. 20 If it is detected that the obstacle is a low-damaged obstacle, the next vehicle between the vehicle or wall that is expected to be highly harmful to the vehicle occupant farthest from the target object and the vehicle Set the required reception waiting time twait at the position of distance d2 that will transition in the measurement cycle. The reception standby time set in step S29 can be calculated by the following equation (10) using the values of the distance d between the host vehicle and the object, the relative speed v, and the relative acceleration a.

Vsound indicates the speed of sound, and t indicates the current reception standby time.

[Control example of reception waiting time setting]
For example, as shown in FIG. 23, an example of control when the object outside the vehicle closest to the host vehicle is a low-damagement obstacle such as a newspaper and the vehicle is approaching from a distance farther than the low-damagement obstacle. Is shown below.

  In the case of the situation as shown in FIG. 23, if it is soft and small like a newspaper, it can be assumed that even if it collides with the own vehicle, the harmfulness to the own vehicle is low, so the reflected wave from this low harming obstacle Is ignored, and the reflected wave from the following vehicle at a longer distance than the low-damaging obstacle is detected. With this action, it is possible to accurately capture the reflected wave from the following vehicle at a long distance, and to narrow down the measurement cycle by narrowing the detection object to a highly harmful object.

  In addition, as described in the second embodiment, it is possible to set the amplitude so that the reflected wave from the subsequent object outside the vehicle does not clip, so that the relative speed with respect to the car or the wall that is expected to be highly harmful is set. It is possible to detect accurately.

  Next, the effect will be described.

  (6) The controller 20 predicts the distance between the vehicle and the object outside the vehicle from the distance between the vehicle and the object outside the vehicle, the relative speed, and the relative acceleration, and the ultrasonic sensor 10 based on the prediction. Has set the reception standby time to wait for the reception of the reflected wave. Therefore, since it is possible to shorten the time of one transmission / reception cycle and increase the data density, it is possible to set the reception standby time to a time at which a reflected wave will be received at a minimum. Therefore, especially before the occurrence of a collision, the reliability of distance and speed data can be increased by increasing the number of measurement cycles and increasing the data density, and it is possible to accurately determine the collision between the vehicle and the object outside the vehicle. Can be done well.

  (7) In the controller 20, the reception standby time is set for a highly harmful object such as a car or a wall. Accordingly, it is possible to accurately capture a reflected wave from a highly harmful object outside the vehicle at a longer distance, and the detection target can be narrowed down to a highly harmful object and the measurement cycle can be shortened.

  Next, Example 4 will be described. Since the operational effects are basically the same as those of the third embodiment, the same components are denoted by the same reference numerals, description thereof is omitted, and only different components are described.

  In the third embodiment, the reception standby time, which is the time to wait for the reception of the reflected wave after the ultrasonic sensor 10 transmits the transmission wave, is set. However, in this embodiment, the object outside the vehicle is a predetermined object with respect to the own vehicle. Judgment is made if it is inside the angle, and if it is judged that it is inside the predetermined angle, it is judged that there is a high possibility that the vehicle and the object outside the vehicle will collide in the future, and the collision judgment is made. The point is different.

[Collision determination control processing]
FIG. 24 is a flowchart showing the flow of processing performed in the controller 20 in the present embodiment.

  In step S31, the transmission power of the ultrasonic wave to be transmitted is set. In the first cycle immediately after the start of the system, the transmission power is determined by the initial value stored in the controller 20 in advance.

  In step S32, an ultrasonic wave is transmitted, and when the transmission is completed, the process proceeds to step S33, and reception of the reflected ultrasonic wave transmitted in step S32 is started.

  In step S33, the received power (amplitude) of the received reflected wave is amplified by an amplifier (not shown), and the received power information is output to each device.

  In step S34, the distance and relative speed between the vehicle and the object outside the vehicle are calculated.

  In step S35, a threshold value is set for determining whether the object outside the vehicle is within a predetermined angle from the distance between the vehicle and the object outside the vehicle.

  In step S36, when the amplitude of the received reflected wave is equal to or larger than the threshold set in step S35, the position of the object outside the vehicle is within a predetermined angle, and a collision between the own vehicle and the object outside the vehicle is determined, The process proceeds to step S37 in order to start the determination for operating the restraining device 30. On the other hand, in the case of the threshold value or less, the position of the object outside the vehicle is not at a predetermined angle and the possibility of collision between the own vehicle and the object outside the vehicle is low, so that the reflected wave from the other object outside the vehicle is received. Return to step S33. This step S36 corresponds to the determination start means of the present invention.

  In step S37, it is determined whether the type of the object outside the vehicle is a low-damaging obstacle, a wall, or a car, and the process proceeds to step S38, step S41, and step S42.

  In step S38, since there is a high possibility of a collision with an object outside the vehicle, it is determined whether or not the occupant restraint device 30 is to be operated, and if it is determined to be operated, the process proceeds to step S39, and is determined not to be operated. To step S41.

  In step S39, it is determined whether or not the type of the object outside the vehicle determined in step S37 is a car or a wall. If the object is a car or a wall, the process proceeds to step S40. Migrate to

  In step S40, since it is a scene where occupant protection is required, an operation is commanded to the occupant restraint device 30.

  In step S41, an outside reception waiting time is set according to the type of the outside object.

  In step S42, the transmission power to be transmitted next time is determined according to the distance between the vehicle and the object outside the vehicle and the type of the object outside the vehicle, and the process returns to step S31.

[Judgment start control]
Next, the processing performed in step S36 of FIG. 24 corresponding to the determination start means of the present invention added in the present embodiment will be described in detail.

  FIG. 25 is a distribution diagram of sensitivity with respect to the angle of the sensor used. A general ultrasonic sensor has a tendency for sensitivity to become extremely low as the angle between the front surface of the sensor and an object increases. Therefore, the threshold for the angle in step S35 in FIG. 23 at a distance L as an example is set so as to detect only a vehicle approaching from substantially directly behind the host vehicle.

In the sensitivity diagram in FIG. 25, it is shown at about 15 degrees to the left and right. However, it is preferable that the setting of the angle threshold is determined according to a target value that the occupant protection device 1 to which the present technology is applied should correspond. For example, as shown in FIG. 25, when an almost vertical rear of the own vehicle is set to +/− 15 degrees, an intersection 110 where an angle line of +/− 15 degrees and a sensitivity diagram intersect is obtained. The threshold at this distance is set as a value indicated by the intersection 110. Furthermore, since the amplitude of the reflected wave from the non-vehicle object decreases as the distance between the non-vehicle object and the host vehicle increases, this threshold value is made variable according to the distance as shown in FIG. As the relationship of the relative distance in FIG.
L5>L4>L3>L2> L1
Set to be. That is, when the relative distance to the object is long, the threshold value is set to a small value. Conversely, when the relative distance to the object is short, the threshold value is set to a large value. In particular, although not shown, this threshold value is set so as to have the same dimension as the amplitude value by multiplying the value of the intersection 110 in FIG. 24 by a predetermined coefficient.

  The threshold value set in step S35 in FIG. 24 is compared with the amplitude of the received reflected wave. If the amplitude is equal to or greater than the threshold value, it is determined that there is an object inside the predetermined angle. Since it is predicted that the possibility of a collision is high, the type of the object outside the vehicle is determined, the restraint device operation determination is performed, and the like. On the other hand, if the amplitude is smaller than the threshold value, it is determined that there is an object outside the predetermined angle, and it is predicted that there is a low possibility of a collision with the vehicle in the future. Perform return reception.

[Judgment start control example]
For example, as shown in FIG. 25, an example of control when the object outside the vehicle is in front of the host vehicle and behind the vehicle at an angle of 30 degrees with respect to the host vehicle is shown below.

  As shown in FIG. 25, for example, since the reflected wave from the vehicle 104a located at the distance L in the front-rear direction with respect to the own vehicle exceeds the threshold value, a determination is made to activate the occupant restraint device 30. On the other hand, since the reflected wave from the vehicle 104b located at the rear distance L at an angle of 30 degrees with respect to the own vehicle does not exceed the threshold value, the determination to operate the occupant restraint device 30 is not performed. Wait for reception of reflected waves from objects outside the vehicle.

  Next, the effect will be described.

  (8) The controller 20 determines that the direction of the object outside the vehicle is within the set angle from the received reflected wave, and if the direction of the object outside the vehicle is within the set angle, When a collision with an object outside the vehicle is determined, but not within the set angle, a reflected wave is received from another object outside the vehicle without performing the collision determination. Therefore, since the collision determination is performed by focusing on an object outside the vehicle having a high possibility of collision, the determination accuracy can be improved.

  (9) The controller 20 sets a threshold for determining whether the object outside the vehicle is within a predetermined angle from the distance between the host vehicle and the object outside the vehicle, and the received power of the received reflected wave is lower than the threshold. When it is large, it is determined that the direction of the object outside the vehicle is within the set angle. Therefore, regardless of the distance between the vehicle and the object outside the vehicle, it can be judged whether the received reflected wave is from the object outside the vehicle within a predetermined angle, and the object outside the vehicle behind the vehicle that has a high possibility of collision. Since it becomes possible to selectively perform collision determination on only an object, the determination accuracy can be improved.

  (10) When the amplitude of the reflected wave from the object outside the vehicle is less than the threshold value, the controller 20 receives the reflected wave from another object outside the vehicle. Therefore, since the collision determination is performed by focusing on an object outside the vehicle having a high possibility of collision, the determination accuracy can be improved.

  Next, Example 5 will be described. Since the operational effects are basically the same as those of the fourth embodiment, the same components are denoted by the same reference numerals, description thereof is omitted, and only different components are described.

  Next, Example 5 will be described. Since the operational effects are basically the same as those of the fourth embodiment, the same components are denoted by the same reference numerals, description thereof is omitted, and only different components are described.

  In the fourth embodiment, the set value that is determined to be within the predetermined angle is set according to the distance between the host vehicle and the object outside the vehicle, but in the present embodiment, the set value is further set according to the type of the object outside the vehicle. The point to set is different.

[Collision determination control processing]
FIG. 27 is a flowchart showing the flow of processing performed in the controller 20 in this embodiment.

  In step S51, the transmission power of the ultrasonic wave to be transmitted is set. In the first cycle immediately after the start of the system, the transmission power is determined by the initial value stored in the controller 20 in advance.

  In step S52, an ultrasonic wave is transmitted. When the transmission is completed, the process proceeds to step S53, and reception of the reflected ultrasonic wave transmitted in step S52 is started.

  In step S53, the received power (amplitude) of the received reflected wave is amplified by an amplifier (not shown), and the received power information is output to each device.

  In step S54, the distance and relative speed between the vehicle and the object outside the vehicle are calculated.

  In step S55, it is determined whether the type of the object outside the vehicle is a low-damaging obstacle, a wall, or a vehicle, and the process proceeds to step S56.

  In step S56, a threshold for determining whether or not the vehicle outside object is within a predetermined angle is set from the distance between the vehicle and the vehicle outside object and the type of the vehicle outside object.

  In step S57, when the amplitude of the received reflected wave is equal to or larger than the threshold set in step S56, it is determined that the object outside the vehicle is inside the predetermined angle, and the process proceeds to step S58. It is determined that the object outside the vehicle is at a predetermined angle, and the process returns to step S53.

  In step S58, it is determined whether or not the occupant restraint device 30 is to be operated. If it is determined that the occupant restraint device 30 is to be operated, the process proceeds to step S59, and if it is determined not to be operated, the process proceeds to step S51.

  In step S59, it is determined whether or not the type of the object outside the vehicle determined in step S55 is a car or a wall. If the object is a car or a wall, the process proceeds to step S60. Migrate to

  In step S60, since it is a scene where occupant protection is required, an operation is commanded to the occupant restraint device 30.

  In step S61, the outside reception waiting time is set according to the type of the outside object.

  In step S62, the transmission power to be transmitted next time is determined according to the distance between the host vehicle and the object outside the vehicle and the type of the object outside the vehicle, and the process returns to step S51.

[Judgment start control]
In the present embodiment, the angle threshold value is set in step S56. However, as in the fourth embodiment, not only the angle threshold value is made variable according to the distance, but also the type of the object outside the vehicle detected in step S55. The angle threshold value is made variable according to the above.

  As shown in FIG. 27, in the case of a predetermined distance, a threshold value in the case where the outside object is a wall, a threshold value in the case where the outside object is a car, and a threshold value in the case where the outside object is a low-damaging obstacle are provided. . The relationship between these threshold values is that the wall threshold value is the largest value, the low harming obstacle threshold value is the smallest value, and the vehicle threshold value is between the wall threshold value and the low harming obstacle-like threshold value. As shown in FIG. 17 of the second embodiment, the maximum amplitude of the reflected wave is large in the case of a wall, and the maximum amplitude of the reflected wave is small in the case of a low-damaging obstacle. Along with this, the angle threshold is also set according to the three types of objects. In FIG. 28, the case where the distance is constant is described, but these three kinds of angle threshold values are variable according to the distance as described above. The variable method is the same as in the fourth embodiment.

  In this embodiment, the angle threshold is made variable according to the distance between the type of the object outside the vehicle and the object outside the vehicle, so that the difference in the amplitude of the reflected wave due to the difference in the object outside the vehicle is ignored, and the object behind the vehicle Only an object can be selectively detected, and a more accurate collision determination can be performed.

  Next, the effect will be described.

  (11) In the controller 20, the threshold value for determining whether the object outside the vehicle is inside the predetermined angle in the order of the low harm obstacle, the car, and the wall is set to be large. Therefore, it is possible to determine whether the received reflected wave is from an object outside the vehicle within a predetermined angle regardless of the kind of low-damaging obstacles, cars, walls, etc. with different reflectivities. Since it becomes possible to selectively detect only an object outside the vehicle behind a high own vehicle, a more accurate collision determination can be performed.

  The occupant protection device of the present invention has been described based on the first to fifth embodiments. However, the specific configuration is not limited to this embodiment, and the claims relate to each claim. Design changes and additions are allowed without departing from the spirit of the invention.

  For example, in the embodiment, the example in which the ultrasonic sensor 10 is provided near the center of the bumper fascia 101 is shown, but the ultrasonic sensor 10 may be provided in front of the vehicle, on the side, and in the corner portion. Further, the ultrasonic sensor 10 may be installed in the rear combination lamp 102 or the trunk lid 103 in FIG.

  Further, although an example in which one ultrasonic sensor 10 is installed is shown, a plurality of ultrasonic sensors 10 may be installed.

  Moreover, you may have a function of only one of a transmission function and a reception function.

  In the first to fifth embodiments, the example of the collision determination device using the ultrasonic sensor has been described. However, the own vehicle is detected from the Doppler frequency such as the pulse method, the two-frequency CW method, and the SS method of the microwave radar and the millimeter wave radar. You may apply to the collision determination apparatus using what calculates the relative speed of a vehicle and a non-vehicle object.

1 is a system diagram of an occupant protection device equipped with a collision determination device according to a first embodiment. It is a figure which shows the position of the ultrasonic sensor based on Example 1. FIG. 3 is a flowchart illustrating a flow of processing performed by a CPU of a controller according to the first embodiment. It is a figure explaining the clip phenomenon of a waveform based on Example 1. FIG. It is a figure explaining the clip phenomenon of a waveform based on Example 1. FIG. It is a figure explaining the clip phenomenon of a waveform based on Example 1. FIG. It is a distance-power diagram which shows the relationship between the distance of the own vehicle and a non-vehicle object, and the transmission power transmitted next time based on Example 1. FIG. It is a figure explaining the time after the ultrasonic sensor which concerns on Example 1 transmits after receiving an ultrasonic wave. It is a figure which shows the reflected wave which the ultrasonic sensor based on Example 1 received. It is a figure which shows calculation of an envelope based on Example 1. FIG. It is a figure which shows the envelope of the reflected wave for every object outside a vehicle based on Example 1. FIG. It is a figure which shows the time integral value of the envelope for every object outside a vehicle based on Example 1. FIG. It is a figure which shows the waveform of the reflected wave for every object outside a vehicle based on Example 1, and the distortion factor of the waveform of this reflected wave. It is a figure which shows the kind of target object which discriminate | determines from the time integral value of the envelope of a reflected wave, and the distortion rate of a waveform based on Example 1. FIG. It is the figure which showed the time integral value of the envelope of a reflected wave, the distortion rate of a waveform, and the action | operation of a passenger | crew restraint apparatus and the non-operation based on Example 1. FIG. It is a figure which shows the transmission power control of the transmission wave according to the distance of the own vehicle and an external vehicle object based on Example 1. FIG. 10 is a flowchart illustrating a flow of processing performed by a CPU of a controller according to the second embodiment. It is a figure which compares the maximum amplitude of the reflected wave from each of the low-damaging obstacle, vehicle, and wall which are the same distance from the own vehicle based on Example 2. FIG. It is a distance-power diagram which shows the relationship between the distance of the own vehicle according to Example 2, the distance of the own vehicle according to a non-vehicle object, and a non-vehicle object, and the transmission power transmitted next time. 12 is a flowchart illustrating a flow of processing performed by a CPU of a controller according to a third embodiment. It is a figure explaining the reception waiting time based on Example 3. FIG. It is a figure explaining the setting of the reception waiting time based on Example 3. FIG. It is a figure explaining the setting of the reception waiting time based on Example 3. FIG. 10 is a flowchart illustrating a flow of processing performed in a CPU of a controller according to a fourth embodiment. It is a distribution diagram of the sensitivity of the ultrasonic sensor with respect to the angle of the object outside a vehicle based on Example 4. FIG. It is a distribution diagram of the sensitivity of the ultrasonic sensor with respect to the angle and distance of a target object outside a vehicle concerning Example 4. 10 is a flowchart illustrating a flow of processing performed by a CPU of a controller according to a fifth embodiment. FIG. 10 is a distribution diagram of sensitivity of an ultrasonic sensor with respect to an angle and a type of a non-vehicle object according to a fifth embodiment.

Explanation of symbols

1 Crew Protection Device 10 Ultrasonic Sensor 20 Controller 23 CPU
30 Crew restraint device

Claims (10)

A transmitter for transmitting a transmission wave to an object outside the vehicle;
Transmission power setting means for setting the transmission power transmitted by the transmitter;
A receiver for receiving a reflected wave with respect to the transmission wave from the object outside the vehicle;
Transmission / reception time calculation means for calculating transmission / reception time from when the transmitter transmits a transmission wave to when the receiver receives a reflected wave; and
A distance calculation means for calculating the distance between the outside object whether et vehicle the transceiver time,
Estimating the center of the amplitude of the waveform of the reflected wave, calculating the frequency from the period of the reflected wave at the center of the amplitude, and using the frequency of the transmitted wave and the frequency of the reflected wave, A relative speed calculating means for calculating a relative speed with the object;
A collision determination means for performing a collision determination between the host vehicle and the object outside the vehicle based on the distance between the host vehicle and the object outside the vehicle and the relative speed;
In a collision determination device comprising:
Reception power detection means for detecting the reception power of the reflected wave;
The percentage in which distortion rate of the harmonic components of the reflected wave with respect to the frequency of the transmission wave, and the integral value of the reflected wave, from the two signals, the type discrimination means for discriminating the type of the outside object,
Provided,
The transmission power setting means sets the transmission power based on the type of the object outside the vehicle determined by the type determination means, and decreases the transmission power of the transmission wave as the reception power of the reflected wave increases. The collision determination apparatus characterized by the above-mentioned. The collision determination device according to claim 1,
The collision determination apparatus according to claim 1, wherein the transmission power setting means decreases the amplitude of the transmission wave as the amplitude of the reflected wave increases. In the collision determination device according to claim 1 or 2,
Providing a relative acceleration calculating means for calculating a relative acceleration between the subject vehicle and the object outside the vehicle from the reflected wave;
The collision determination means, wherein the transmission power setting means sets the transmission power from the distance, the relative speed, and the relative acceleration. In the collision determination device according to claim 3,
Provided is a reception standby time setting means for setting a reception standby time for the receiver to wait for reception of the reflected wave from the distance between the vehicle and the object outside the vehicle, the relative speed, and the relative acceleration. A collision determination device characterized by the above. In the collision determination device according to claim 4,
A harm determining means for discriminating the object outside the vehicle into a first obstacle having a low harm and a second obstacle having a high harm ;
The reception waiting time setting means, when the non-vehicle object is a first obstacle, the distance between the other vehicle object and the own vehicle that are farther than the non-vehicle object, the relative speed, The collision determination apparatus, wherein the reception waiting time is set from the relative acceleration. The collision determination device according to any one of claims 1 to 5,
When the reception power of the reflected wave is larger than the set value, the collision determination apparatus characterized by comprising a determination start means for starting the collision determination of the own vehicle and the outside object. In the collision determination device according to claim 6,
The said determination start means sets the said setting value small, so that the said distance of the said own vehicle and the said vehicle external object is large, The collision determination apparatus characterized by the above-mentioned. In the collision determination device according to claim 6 or claim 7,
The determination start means, when the reception power of the reflected wave is less than the set value, the collision determination device and performs the reception of other reflected waves. In the collision determination device according to any one of claims 6 to 8,
The collision determination apparatus, wherein the determination start unit sets the set value according to a type of the object outside the vehicle. A transmitter for transmitting a transmission wave to an object outside the vehicle;
Transmission power setting means for setting the transmission power transmitted by the transmitter;
A receiver for receiving a reflected wave with respect to the transmission wave from the object outside the vehicle;
Transmission / reception time calculation means for calculating transmission / reception time from when the transmitter transmits a transmission wave to when the receiver receives a reflected wave; and
A distance calculation means for calculating the distance between the outside object whether et vehicle the transceiver time,
Estimating the center of the amplitude of the waveform of the reflected wave, calculating the frequency from the period of the reflected wave at the center of the amplitude, and using the frequency of the transmitted wave and the frequency of the reflected wave, A relative speed calculating means for calculating a relative speed with the object;
A collision determination means for performing a collision determination between the host vehicle and the object outside the vehicle based on the distance between the host vehicle and the object outside the vehicle and the relative speed;
In a collision determination device comprising:
Setting the transmission power based on the type of the a strain which is a ratio of the harmonic component of the reflected wave with respect to the frequency of the transmitted wave, and the integral value of the reflected wave, the outside object is determined from the two signals In addition, the collision determination apparatus is characterized in that the transmission power of the transmission wave is reduced and the reception power of the reflection wave is reduced as the reception power of the reflection wave increases.

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