JP2005521584A - Collision detector system - Google Patents

Abstract

A collision detector that detects and evaluates a collision and outputs an output signal to deploy a pedestrian protection system (119) mounted on the vehicle is a sensor device (101) attached to the front of the vehicle to detect the collision. ). An evaluator (108) is provided which evaluates the output of the sensor and outputs an output signal when a predetermined threshold is exceeded so that the pedestrian protection system (119) is not activated by a collision with a very light object. To. In addition, a chassis-installed accelerometer (115) is provided, which is adapted to provide a signal representing the total deceleration exerted on the vehicle. An inhibitor (109) is provided that inhibits the generation of a signal that activates the pedestrian protection system (119) when the output signal from the accelerometer exceeds a predetermined threshold.

Description

  The present invention relates to a collision detector system, and more particularly to a collision detector system that is mounted on an automobile to detect a certain type or nature of a collision, such as a collision with a pedestrian.

  It has been proposed to equip a car with a safety device that has provided some degree of protection to self-propelled vehicles, such as pedestrians that have been hit by a car. One type of such safety device is to move the pedestrian's head upward along the "A" strut of the car to prevent injury from colliding with the "A" strut of the car (also called the A pillar). An inflatable element having a portion extending to the surface. Another form of such a safety device is to flip the rear part of the hood or bonnet of the car away from the engine underneath the hood or bonnet so that the hood or bonnet collides with the pedestrian's head. Can be deformed in some cases, resulting in a reduced risk of injury.

  The proposed conventional collision detector uses various sensors, such as an accelerometer, a deformation sensor and a force sensor, provided in the bumper of the automobile. The output signal that activates the safety device that protects the pedestrian is issued when the signal from the sensor is above or below a predetermined threshold.

  In order to be able to distinguish a collision with a pedestrian from a collision with a light object, e.g. a bird, the sensor depends only on the characteristics of the object struck, e.g. the mass of the object in an accident situation Thus, in some cases, it is ideal to provide an output signal in conjunction with other known and measurable parameters, such as the speed of the vehicle.

  Of course, it goes without saying that it may be extremely inappropriate to operate the pedestrian protection device in the event of a major accident, for example, a collision with another vehicle. Pedestrian protection devices can significantly impair the visibility of an automobile driver. If the pedestrian protection device is a device that flips up the rear edge of the hood or bonnet, the rear part of the hood or bonnet may push through the windshield or windshield during a frontal collision, resulting in the hood Or the rear part of the bonnet hits the driver of the car and / or passengers in the front seat, which causes undesirable injuries.

  The present invention is to provide an improved collision detector system.

  According to the present invention, there is provided a collision detector system for detecting a collision and generating an output signal for operating a pedestrian protection system mounted on an automobile, which is attached to the front of the automobile and detects the collision. At least one sensor for detecting and an evaluator for evaluating the output of the sensor and generating an output signal if the pedestrian detection criteria are met, wherein the system is a signal representative of the total deceleration exerted on the vehicle The system further includes an inhibitor that inhibits the generation of the output signal if the signal from the accelerometer meets the inhibition criteria. .

Preferably, the accelerometer providing a signal representative of total deceleration is provided at a substantially central location on the vehicle.
Advantageously, the deterrence criterion is met if the sliding window average value of the signal produced by the accelerometer exceeds a predetermined value.
As a variant, the suppression criterion is fulfilled when the integral value of the signal produced by the accelerometer exceeds a predetermined value.

  Advantageously, the sensor is configured to detect a variable that depends on the nature of the crash, the sensor being provided on or in an element adapted to be mounted on the front of the vehicle, said element having a predetermined stiffness. And having a deformable portion positioned to deform upon impact, wherein the stiffness varies according to at least one parameter, the detector comprises a device for measuring said at least one parameter, said evaluator Is configured to evaluate the output of the sensor in combination with the measured degree of stiffness corresponding to the at least one parameter and to generate the output signal when a predetermined threshold is exceeded.

Preferably, the sensor is a force sensor.
Advantageously, the sensor comprises at least one accelerometer attached to the element, the element comprising a flexible support for attaching the element to the front of the vehicle.
Preferably, the sensor consists of two said accelerometers, said element comprising two said flexible supports, each accelerometer being installed on or in each of the flexible supports Is provided.
Advantageously, the sensor comprises an elongate sensor provided in the element, the sensor being arranged such that a force is applied to the sensor when the deformable part of the element is deformed.

In one embodiment, the sensor is a piezoelectric cable.
Advantageously, a plurality of piezoelectric cables are provided.
Advantageously, the piezoelectric cables partially overlap each other.

In another embodiment, the sensor is at least one pressure tube.
Advantageously, a plurality of pressure tubes are provided.
Advantageously, the pressure tubes partially overlap each other.
Advantageously, each pressure tube is of a non-uniform cross section having a substantially vertical section and a smaller vertical section.
Preferably, each pressure tube is provided with a vent hole.

Advantageously, the deformable part of the element is made of a deformable foam material.
Preferably, the element has a substantially rigid beam and the foam is attached to the beam.
Advantageously, the element comprises at least one touch sensor and the detector generates the output signal only when output is provided by the evaluator and output is provided by the touch sensor. Has a logical structure.

Advantageously, the at least one parameter comprises the thickness of the deformable part of the element, the deformable part of the element being of non-uniform thickness.
Preferably, the device for measuring the at least one parameter comprises a device for measuring a collision location and determining the thickness of the element according to the collision location.
Advantageously, said means for measuring the position of the collision comprises a device for executing an algorithm by comparing the accelerations applied to the two accelerometers.

As a variant, an analyzer is provided to determine which cable or combination of cables is producing a signal by analyzing signals from different piezoelectric cables in order to locate the collision point.
Alternatively, an analyzer is provided to determine which pressure tube or combination of pressure tubes is analyzing the pressure from different pressure tubes to locate the impact location.

Preferably, the at least one parameter includes a temperature, and at least one temperature sensor is provided for detecting the temperature.
Advantageously, a plurality of temperature sensors are provided.

Advantageously, it is determined by the means for locating the impact point which temperature sensor or which temperature sensors are generating the output signal used by the evaluator.
Advantageously, the evaluator is further configured to evaluate a signal representative of the vehicle speed prior to the collision, where the evaluator is above the first relatively low threshold and below the second relatively high threshold. Only to generate the output.
Advantageously, the first threshold is 20 km / h and the second threshold is 60 km / h.

  In order that the present invention may be readily understood and other features thereof may be understood, the invention will now be described by way of example with reference to the accompanying drawings.

上式において、Ｆは、衝突状況の間にバンパの特定の点又は領域に加えられた力、ｓは、その衝突点又は領域の実際の変位である。質量ｍの物体と衝突した状況では、バンパが取り付けられている自動車の速度が衝突直前においてはνであり、ｋを定数とすると、次式が成り立つ。

The rigidity k of a member, for example, an automobile bumper, is defined as

Where F is the force applied to a particular point or area of the bumper during a collision situation and s is the actual displacement of that collision point or area. In a situation where the vehicle collides with an object of mass m, the speed of the automobile to which the bumper is attached is ν immediately before the collision, and the following equation holds when k is a constant.

したがって、

加速度計を用いた場合、加速度についての式は、ｓの２次導関数である。

力Ｆ＝ｋ・ｓであり、かくして、

ただし、

それ故、Ｆ（ｔ）＝０である。 If the deformation is not elastic (this is considered common in the case of motor vehicle accidents), this equation is valid for the period t expressed by:

Therefore,

When using an accelerometer, the equation for acceleration is the second derivative of s.

Force F = k · s, thus

However,

Therefore, F (t) = 0.

  The mathematical analysis described above relates only to actual collision points. If the sensor is located behind the collision location, the signal is the ratio of the total stiffness to the stiffness behind the sensor, i.e. the stiffness ratio between the sensor and the vehicle chassis to which the member is attached. Converted by an equal factor. In order to obtain a high signal, it is necessary that the rigidity in front of the sensor is high and the rigidity behind the sensor is low. However, in order to minimize the risk of injuring pedestrians, the previous stiffness needs to be low. A good compromise can be found if the stiffness behind the sensor is less than 1/10 of the total stiffness of the car bumper.

  Therefore, in the above situation, if the vehicle speed ν immediately before the collision is known and the stiffness k regarding the automobile bumper in the region where the collision has occurred, m, that is, the mass of the object in which the collision has occurred can be calculated. .

  Of course, once the mass m of the object is determined, this value can be used in an algorithm to determine whether the safety device should or should not generate a control signal that protects the pedestrian. Of course, after considering that the safety device as a pedestrian protection means is considered effective only when the collision speed with the pedestrian is faster than 20 km / h and lower than 60 km / h, The algorithm can utilize other parameters, such as absolute vehicle speed. If the vehicle speed is less than 20 km / h or more than 60 km / h, today's safety devices that are able to protect pedestrians are considered to have no obvious advantageous effect.

  Referring initially to FIG. 1 of the accompanying drawings, a bumper (or fender) assembly 1 is attached to a self-propelled vehicle 2, for example, a front portion of an automobile, by two flexible supports 3, 4; Each of these supports is provided adjacent to each end of the bumper. Each support 3, 4 may generally take the form of a tubular housing, which is made of a material that has a thickness that will collapse or flex during typical impact situations involving pedestrians. It has been. Thus, each support can be considered a “crash box”.

  Two accelerometers 5 and 6 are attached to the rear portion of the bumper 1. The accelerometer 5 is provided in the “crash box” 3 and the accelerometer 6 is provided in the “crash box” 4 so that each crush box can protect the accelerometer to some extent. . However, the accelerometer can be placed on the crash box or somewhere adjacent to the crash box, and in some cases as part of the bumper itself. In the illustrated embodiment, each accelerometer is attached to the rear face of the relatively rigid beam 7 that forms part of the bumper 1. The front face of the beam 7 is provided with a flexible covering 8, which in the illustrated configuration is constituted by a “foam” block fixed to the front face of the beam 7. The foam is a flexible foam, which is of uniform structure and thus has a known degree of “rigidity”.

  However, the foam need not be of uniform thickness, and thus the absolute stiffness of the foam at any particular point or location is determined by the thickness of the foam at that particular location.

  The foam stiffness at any particular location or location can be calculated from the design data and the calculated stiffness can be stored in memory in the form of a “look-up table”. Thus, as will become apparent from the following description, the location of the collision location can be calculated, and then the associated stiffness can be determined from a “look-up” table for that location.

加速度計５，６からの出力信号ａ_A，ａ_Bを分析することにより衝突が生じた正確な箇所９を求めると、バンパについての記憶データを用いてその箇所におけるフォーム８の剛性を求めることができ、その結果、上述の数学的分析を利用して、衝突物体の質量を求めることができる。かくして、用いられるアルゴリズムは、フォームの剛性ｋ及び「クラッシュボックス」３，４の剛性を利用している。かくして、センサの前及び後に位置する要素の剛性が利用される。 If a collision with a pedestrian occurs and the force indicated by arrow F is applied to a specific location, for example, location 9 on the bumper, the distance between the two accelerometers is 1 _O , and the location of the collision Assuming that the distance between 9 and the first accelerometer 5 is l _A , the accelerometer 5 outputs an output signal a _A , and the second accelerometer 6 outputs an output signal a _B and outputs The signal is represented by the force F _A applied to the first accelerometer 5 and the force F _B applied to the second accelerometer 6, where F = F _A + F _B. The exact position of the location 9 relative to the accelerometers 5 and 6 can be determined. This is because the following equation holds.

When the accurate location 9 where the collision has occurred is obtained by analyzing the output signals a _A and a _B from the accelerometers 5 and 6, the rigidity of the foam 8 at that location can be obtained using stored data about the bumper. As a result, the mass of the collision object can be obtained using the mathematical analysis described above. Thus, the algorithm used utilizes the stiffness k of the foam and the stiffness of the “crash box” 3, 4. Thus, the stiffness of the elements located before and after the sensor is utilized.

  FIG. 2 shows a bumper 11 attached to the front of an automobile 12 by means of a flexible support or “crash box” 13, 14 of the type described above. Adjacent to the opposite end. The bumper has a substantially rigid beam 15 extending between the supports 13, 14, with a foam element 16 attached to the front of the beam. A sensor element 17 is provided between the foam element and the beam, which sensor element is in the form of either a pressure tube or a piezoelectric cable. The sensor responds to all forces applied to the bumper regardless of the exact location where the force is applied.

  The pressure pipe is a pipe having a wall that is easily bent and containing a gas or a liquid. The gas or liquid is in communication with the pressure sensor. As force is applied to the tube and the tube deforms, the pressure of the gas or liquid increases and this pressure increase is detected by a pressure sensor.

  A piezoelectric cable is an elongated cable having an elongated piezoelectric material provided between two elongated electrodes. A piezoelectric material is a material that, when compressed, creates an electrical potential across its opposite faces. Thus, the cable is such that when a force is applied to the cable, it creates a potential that can be detected. A piezoelectric material uses a dielectric having good piezoelectric characteristics.

  In some forms of piezoelectric cable, the piezoelectric material is divided into a plurality of small segments, and individual electrodes associated with each segment are provided so that the output produced by the piezoelectric cable is accurate with the force applied to the cable. The location is automatically specified. Thus, such a cable can immediately locate the collision point. However, if pressure tubes are used, the pressure tubes may be divided into separate segments that overlap one another, or alternatively, if separate position sensors are utilized, in the illustrated embodiment, the form 16 is Since it does not have a uniform thickness and thus does not have a uniform rigidity as a whole, the collision location can be obtained. In the above embodiment, the collision location is obtained from the stored information on the bumper by obtaining the collision location. It would be reasonable to be able to determine the relevant stiffness for.

Considering the effective stiffness k _{1 at} the substantially central location (where the foam is very thick) of the bumper of FIG. 2, the effective stiffness k ₁ is the foam stiffness k _{1f at the} relevant substantially central location. And also depends on the stiffness k _1b of the beam 15 at the relevant substantially central location, which can be expressed as:

Since the beam is “soft” between the supports 13, 14, the effective stiffness of the beam at the location between the supports, k _1b, is the effective stiffness of the beam adjacent to one of the supports 13. _Is smaller than k _2b . It should also be noted that k _1f is much smaller than k _{2f at} locations adjacent to the support 13. This is because the foam is "soft" where it is thick.

  Referring now to FIG. 3, various plots of power compared to time are shown for various combinations of m, k and ν.

但し、

図３にプロットした第１の線、即ち線２１は、質量ｍ₁の物体と有効剛性がｋ₁である図２のビームの中央部分において車速ν₁の衝突について力と時間との関係を表す代表的な線を示している。この線は、最大値に向かって次第に上昇し、次に衝突状況の終わりに突然下降する。線２２は、線２１と類似した状況を示しているが、車速ν₂が増大している。この線は、急勾配の初期の経路を有し、大きな最大力まで上昇するが、線２１と実質的に同一の時点で終わっていることが理解できる。 As described above, the following equation holds for designs and materials having a constant stiffness (k = F / s).

However,

The first line plotted in FIG. 3, ie line 21, represents the relationship between force and time for a collision at vehicle speed ν ₁ in the central part of the beam of FIG. 2 with an object of mass m ₁ and an effective stiffness of k ₁ . A representative line is shown. This line gradually rises towards the maximum value and then suddenly falls at the end of the collision situation. Line 22 shows a situation similar to line 21, but the vehicle speed ν ₂ is increased. It can be seen that this line has a steep initial path and rises to a large maximum force, but ends at substantially the same time as line 21.

A line 23 indicates a force received at the vehicle speed ν ₁ when the vehicle collides with the mass m _{1 in} the region of the effective stiffness k ₂ as shown in FIG. 2 adjacent to the support 13 of the bumper 11. Again, the overall shape of the line is similar to that described above, which rises towards maximum force and ends abruptly. However, although the maximum force is less than the maximum force for line 21 or 22, the time for the force to fall is slow compared to the beginning of the force.

Finally, the line 24 is again received when it collides with an object of mass m ₂ (where m ₂ is greater than m ₁ ) at a vehicle speed ν ₁ in the region where the effective stiffness k ₂ is given. Showing power. The line 24 gradually rises to the maximum value and then ends abruptly. However, the maximum value is greater than the maximum value visible on line 23 and the end of force occurs at a later point in time than on line 23.

  Referring now to FIG. 4, it is possible to use a set of criteria that includes the mass of the impacted object and the speed of the vehicle to generate control signals for the safety device.

上式において、ｍ₁は、歩行者の脚の質量の下限値である。 FIG. 4 is a graph showing a plot representing the relationship between applied force and absolute vehicle speed. As described above, it is appropriate to select a vehicle speed within a predetermined range and generate the control signal only when the vehicle speed before the collision is within the selected range. In FIG. 4, a range of 20 km to 60 km per hour is selected, but this is an arbitrary selection. If a collision is detected while the vehicle is traveling within its speed range, the control signal should only be output if the force F exceeds a threshold.

In the above formula, m ₁ is the lower limit value of the mass of the pedestrian's leg.

It is therefore possible to draw a line with a gradient dF ₁ / dν = √ (k · m ₁ ), which is plotted as line 30 in the graph. Thus, if the mass of the object that has been struck during a particular collision is such as to produce a force that is seen in the region represented by reference numeral 31 located on line 30, an output signal must be generated.

If foam or an equivalent material is used, at least part of the path from the location of the collision point to the vehicle chassis will have a temperature-dependent stiffness k. This is because the foam usually softens with increasing temperature and the value of k decreases.
For many materials or designs, the stiffness k is not independent of s, a or F. The stiffness k may also depend on ν.

For example, if F = f ₁ (k, ν, m) and k = f ₂ (F, ν, T), F can be expressed as a new function of f ₃ .
That is, F = f ₃ (T, ν, m), where f ₃ is independent of F. For simplicity, assume that k is independent of the position of the collision for this analysis.

FIG. 5 shows separate plots of F (t) for the form used for the bumper with the same values for ν and m, but for different T and thus different k.
The first line 40 visible in FIG. 5 shows the effect for a relatively low temperature T1 and thus a relatively high stiffness k ₁ . The total time required to complete the illustrated cycle is relatively short. As indicated by line 41, the temperature T2 and thus relates to low foam stiffness k ₂ than this higher than this, the total time required, but very long, the maximum force is smaller than that of the line 40. The integral value of line 40 (ie, the area under the curve) is the same as the integral value for line 41.

  6 and 7 of the accompanying drawings, another bumper 51 is shown secured to the automobile chassis 52 by two flexible supports, such flexible support. The body may be in the form of crash boxes 53,54. This bumper is provided with a relatively rigid rear beam 55 carrying a foam element 56 on its front face. Formed in the foam element 56 of the illustrated embodiment is a channel that forms two adjacent pressure tubes 57,58. Since the pressure tubes are identical to each other, only the pressure tube 58 will be described. The pressure tube 58 is formed of an elongated tube, and a pressure sensor 59 for providing an output on an output lead wire 60 communicating with the processor 61 is provided in the tube. Each tube may be a channel formed in the foam material. The channel walls should be sealed, and such sealing would be necessary if the foam is an open cell foam. This pressure pipe is provided with a vent hole 61 to the atmosphere so as to accommodate normal air by air pressure. As can be seen most clearly in FIG. 7, the interior of the tube is not of a uniform cross section, but of a “trapezoidal” cross section, which has a considerably larger dimension towards the front of the bumper. The cross section decreases toward the rear of the bumper. This is because when such a tube is compressed, the volume change in the portion of the tube having a large “height” is large compared to the total volume of the chamber.

  It is preferred to use two or more individual tubes rather than just one tube. This is because the effective volume reduction is compared to the total volume for short tubes that extend over a portion of the length of the bumper in any particular collision situation than for long tubes that extend the entire length of the bumper. Because it is bigger. When using multiple tubes "overlapping", by determining which tubes are subject to increased pressure and allowing for the effect of foam thickness at the point of impact It is possible to determine the location of the collision. Similar effects can be achieved by “overlapping” a plurality of piezoelectric cables of the type described above.

  In a preferred embodiment of the present invention, it would be advantageous to have an independent “arming” (safety release) device that must be activated before a control signal can be generated to deploy the safety device. It is done. Such a device would minimize the risk of the control signal being generated in an inappropriate situation due to, for example, one spurious electrical signal.

  FIG. 8 shows a bumper 71 attached to the automobile chassis 72 by flexible supports 73, 74, which are positioned adjacent to the end of the bumper 71 “crash”. It should be in the form of a “box”. The bumper 71 has a beam 75. Mounted on the front of the beam 75 is a body 76 made of flexible foam. A force sensor 77 in the form of one or more pressure tubes or one or more piezoelectric cables is incorporated in the foam body. The sensor 77 outputs an output signal schematically shown as an output 78.

  In front of the sensor 77, a completely separate and independent touch sensor 79 is provided. The touch sensor 79 may simply consist of two conductive foils that are spaced apart from each other by a very short distance in the initial form. If a force is applied to the foam 76, the foils are in electrical contact with each other, thus effectively “shorting” the electrical leads 80, 81 connected to the two foils. Other types of touch sensors can be used, and first the touch sensor 79 must detect the touch condition before generating the control signal, and second, in the manner described above. It will be appreciated that the mass of the object undergoing the collision must be verified to meet the appropriate criteria. The touch sensor may have touch sensor elements that overlap each other to help determine the location of the collision site, as will be described in detail below.

  In the calculation to determine the mass of the object that hits the bumper, the use of the effective stiffness of the material forming the bumper and the stiffness of the mount that attaches the bumper in place was described. The stiffness of the material forming the bumper may depend on the temperature. Thus, in the bumper shown in FIG. 8, a temperature sensor 82 that provides an output 83 is incorporated into the foam, and when the output 83 is sent to the processor for calculations related to the stiffness of the foam body, it is based on the actual temperature. It is advisable to make appropriate adjustments. However, in the case of the embodiment using the piezoelectric cable as described above, a signal representing the temperature can be obtained by measuring and analyzing the capacitance (capacitance) between the electrodes of the cable which changes as a function of the temperature. .

FIG. 9 shows the entire operating system constituting the preferred embodiment of the present invention.
FIG. 9 shows a bumper 100 that can be attached to an automobile as described above using two supports in the form of “crash boxes” located adjacent to the end of the bumper. The bumper 100 has a relatively rigid beam 101 with a foam body 102 attached to the front face of the beam. A force sensor 103 is provided between the foam body 102 and the beam 101, and the force sensor may be in the form of a plurality of pressure tubes or piezoelectric cables. In the embodiment of FIG. 9, three elongate contact sensors 104, 105, 106 are provided, which are in an overlapping state. The contact sensors 104, 105, and 106 are provided in the foam main body 102 in a state of being positioned in front of the force sensor 103. The closest touch sensors 104, 106 are spaced apart from each other, the front touch sensor 105 substantially overlaps each half of the touch sensors 104, 106, and , Extending across the space between the contact sensors 104,106. This relatively simple structure makes it possible to identify five separate contact zones using only three sensors.

  As can be seen, only the contact sensor 104 detects contact when a collision occurs on the leftmost side of the bumper as shown in FIG. If a collision occurs slightly to the right where sensor 104 overlaps sensor 105, both sensors will detect the collision. If the collision further occurs on the right side and no collision occurs at the location where the sensor 105 overlaps the sensor 106, only the intermediate sensor 105 will detect the collision. Both sensors will detect a collision. Finally, if a collision occurs on the rightmost side of the bumper, only sensor 106 will detect the collision. The sensors 104, 105, 106 are all connected to an evaluation unit 107, which determines which sensor or which combination of sensors has detected contact and represents the location where the collision has occurred. Output signal to the processor 108, which executes the pedestrian collision algorithm. The processor 108 is configured to determine the effective stiffness of the associated zone foam from a “look-up table” stored in memory. When any one of the touch sensors detects a touch, an arming signal is sent to a logic component in the form of an “AND gate” 109 that can be suppressed, which also receives input from the processor 108.

  In the illustrated embodiment, a plurality of temperature sensors 110, 111, and 112 are provided in the bumper. The temperature sensor detects the temperature of various regions of the foam body 102. The output signal from the evaluation unit 107 is sent to the temperature selection unit 113, which receives signals from the three temperature sensors 110, 111, 112. Depending on the determination result regarding the collision location from the evaluation unit 107, the temperature of an appropriate temperature sensor or combination of temperature sensors is sent by the temperature selection unit 113 to the processor 108 that executes the pedestrian collision algorithm. The actual temperature can be used to appropriately adjust the selected value of stiffness.

  The processor 108 also receives input from the vehicle speedometer unit 114 indicating the speed of the vehicle just prior to the collision.

  In an embodiment as shown in FIG. 9, another accelerometer 115 is provided, which is preferably attached to the main chassis of the automobile in a central position. Thus, the accelerometer 115 is responsive to the overall acceleration of the vehicle and, as will become apparent, this accelerometer determines whether the vehicle is involved in a collision with a very heavy object, for example another vehicle. In the case of such a collision, it is inappropriate to deploy safety devices intended to protect pedestrians.

The output of accelerometer 115 is integrated at integrator 116 to provide a signal representative of the total speed change of the vehicle over a predetermined period.

  The output of the integrator is sent to the discriminator 117. The discriminator is adapted to determine whether the speed change is such that a collision with an object that is much heavier than a pedestrian has occurred. If the discriminator 117 determines that the change in speed exceeds a predetermined threshold value indicating that a collision with an object heavier than a pedestrian has occurred, a signal that inhibits the AND gate 109 is output on the lead 118. Thus preventing a control signal from being issued at the output of the AND gate.

Without calculating the total velocity change, a low-pass filter may be applied to the acceleration signal, or a “sliding window” average may be calculated, which can be calculated at any point over the previous predetermined period. Is the average value.

  The output of the AND gate 109 is provided to a safety device in the form of a pedestrian protection system 119. Therefore, in the case of a collision that applies a force to a part of the bumper 101, the force is first detected by one or more of the contact detectors 104, 105, 106, so that the evaluation unit 107 hits which area of the bumper. It should be understood that the information is sent to the processor 108 and the arming signal is sent to the AND gate 109. The evaluation unit 107 can also send an appropriate signal to the temperature selection unit 113, thereby sending an appropriate temperature signal to the processor 108.

  The force of the collision is measured by the force sensor 103 and an appropriate force is sent to the processor 108. The processor 108 also receives the instantaneous vehicle speed from the speedometer unit 114. Utilizing the method described above, the processor unit 108 could determine the mass of the collided object. Thus, the processor 108 acts as an evaluator to evaluate the output of the sensor in combination with the determined stiffness of the foam at the location of the collision, thereby calculating the mass of the object involved in the collision. If the mass exceeds a predetermined threshold, an output signal is sent to the AND gate 109. If AND gate 109 is suppressed by a signal on line 118 that exists only if accelerometer 115, integrator 116, and discriminator 117 determine that a collision with a very heavy object, such as another car, has occurred. If not, the control signal will be transmitted from the AND gate 19 to the safety device adapted to protect the pedestrian, and the safety device will be activated.

  From the above, sensors attached to the front of the car, such as accelerometers or force sensors, can be used to distinguish both light and heavy objects, but the sensors are not suitable for heavy or very rigid objects. It will be clear that it is better suited to distinguish light objects since they can be damaged by collisions. A pedestrian protection device of the type in which the hood or bonnet is flipped up should not be activated during a severe collision, for example in a severe collision situation where the hood breaks through the windshield. Thus, when the detector according to the embodiment of the present invention detects a collision, however, only when there is a collision with an object having a mass exceeding a predetermined threshold and only when the collision is not part of a severe collision situation. It is desirable to output an output signal.

  Thus, the preferred configuration of the present invention provides reasonable conditions unless the output signal from the chassis-mounted accelerometer 115 is such that it is given the prospect that the vehicle has experienced a severe crash or accident. Generates a control signal if present.

  In the text description, “comprises” (including) means “includes or consists of” and “comprising” means “including or consisting of”. "Means.

1 is a schematic view of a bumper for an automobile with a sensor in the form of an accelerometer. 1 is a schematic view of an automobile bumper with a force sensor extending along the entire width of the bumper. FIG. 3 is a graph provided for illustrative purposes. FIG. 3 is another graph provided for illustrative purposes. FIG. 6 is yet another graph provided for illustrative purposes. It is a cross-sectional view of a bumper having two pressure tubes. It is VII-VII arrow sectional drawing of FIG. 4 is another schematic diagram of a bumper for a vehicle. 1 is a schematic diagram of an automobile bumper incorporated in a block diagram.

Claims (30)

  A collision detector system for detecting a collision and generating an output signal for operating a pedestrian protection system mounted on an automobile, wherein the at least one sensor is mounted on the front of the automobile and detects the collision. And an evaluator that evaluates the output of the sensor and generates an output signal if the pedestrian detection criteria are met, the system further comprising an accelerometer that provides a signal representative of the total deceleration exerted on the vehicle And the system further comprises an inhibitor for inhibiting the generation of an output signal if the signal from the accelerometer satisfies the inhibition criteria.   The system of claim 1, wherein the accelerometer providing a signal representative of total deceleration is provided at a substantially central location on the vehicle.   3. A system according to claim 1 or 2, characterized in that the deterrence criterion is met if the sliding window average value of the signal produced by the accelerometer exceeds a predetermined value.   The system according to claim 1 or 2, characterized in that the deterrence criterion is met if the integral value of the signal provided by the accelerometer exceeds a predetermined value.   The sensor is configured to detect a variable that depends on the nature of the collision, the sensor being provided on or in an element adapted to be mounted on the front of the vehicle, said element having a predetermined stiffness, Having a deformable portion positioned to deform in response, the stiffness varies according to at least one parameter, the detector comprises a device for measuring the at least one parameter, and the evaluator is measured 2. The apparatus according to claim 1, wherein a sensor output is evaluated in combination with a degree of rigidity corresponding to the at least one parameter, and the output signal is generated when a predetermined threshold value is exceeded. The system described.   The system according to claim 5, wherein the sensor is a force sensor.   7. The system of claim 6, wherein the sensor includes at least one accelerometer attached to the element, the element comprising a flexible support that attaches the element to the front of an automobile.   The sensor consists of two said accelerometers, said element comprising two said flexible supports, each accelerometer being provided installed on or in each of the flexible supports. 8. The system according to claim 7, wherein:   9. The sensor includes an elongate sensor disposed within the element, the sensor being arranged to apply a force to the sensor when a deformable portion of the element is deformed. System.   The system of claim 9, wherein the sensor is a piezoelectric cable.   The system of claim 10, wherein a plurality of piezoelectric cables are provided.   The system of claim 11, wherein the piezoelectric cables partially overlap each other.   The system of claim 9, wherein the sensor is at least one pressure tube.   The system of claim 13, wherein a plurality of pressure tubes are provided.   The system of claim 14, wherein the pressure tubes partially overlap each other.   16. Each of the pressure tubes is of a non-uniform cross section having a substantially vertically extending cross-sectional portion and a smaller vertical extending cross-sectional portion. The system according to claim 1.   The system according to any one of claims 13 to 16, wherein each pressure tube is provided with a vent hole.   18. System according to any one of claims 5 to 17, characterized in that the deformable part of the element is made of a deformable foam material.   The system of claim 18, wherein the element has a substantially rigid beam and the foam is attached to the beam.   The element comprises at least one touch sensor and the detector has a logic structure that generates the output signal only when output is provided by the evaluator and output is provided by the touch sensor. 20. A system according to any one of claims 5 to 19, characterized by:   21. Of the claims 5-20, wherein the at least one parameter includes a thickness of the deformable portion of the element, the deformable portion of the element being of non-uniform thickness. The system according to any one of the above.   The system of claim 21, wherein the apparatus for measuring at least one parameter comprises an apparatus for measuring a collision location and determining the thickness of the element according to the collision location.   23. A system according to claim 22 as a dependent claim of claim 7, wherein the means for measuring the position of the collision comprises a device for comparing the accelerations applied to the two accelerometers and executing an algorithm.   12. The analyzer of claim 11 wherein an analyzer is provided to determine which cable or combination of cables is producing a signal by analyzing signals from different piezoelectric cables to determine the location of the collision. The system of claim 22 as a dependent claim.   An analyzer is provided for analyzing the pressures from different pressure tubes to determine which pressure tube or which combination of pressure tubes is producing a signal in order to locate the collision point. 23. A system according to claim 22 as 14 dependent claims.   26. A system according to any one of claims 5 to 25, wherein the at least one parameter includes a temperature and at least one temperature sensor is provided for detecting the temperature.   27. The system of claim 26, wherein a plurality of temperature sensors are provided.   The dependent claim according to claim 21, characterized in that it is determined by the means for locating the collision point which one or more temperature sensors are generating the output signal used by the evaluator. 28. The system according to claim 27.   The evaluator is further configured to evaluate a signal representative of the vehicle speed prior to the collision, and the evaluator outputs the output only when the vehicle speed is above the first relatively low threshold and below the second relatively high threshold. 29. The system according to any one of claims 5 to 28, wherein the system is configured to generate   29. The system of claim 28, wherein the first threshold is 20 km / hour and the second threshold is 60 km / hour.

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