Method for triggering occupant protection devices in a motor vehicle based on the signals of at least one right and at least one left upfront sensor and the signal of at least one impact sensor arranged centrally in the vehicle

Abstract

Method for triggering occupant protection devices in a motor vehicle (1) based on the signals of at least one right and at least one left upfront sensor (FCS_L, FCS_R) and the signal of at least one impact sensor (G) arranged centrally in the vehicle, wherein the signals are compared with thresholds and an impact type and impact severity are derived therefrom, wherein a plurality of triggering paths with different criteria are provided and a decision is made on the triggering of the occupant protection devices depending thereon, characterized in that in one triggering path, an early triggering of a predetermined selection of occupant protection devices already occurs when the signal of one of the two upfront sensors (FCS_L) already exceeds a second threshold value (th2) with respect to the signal of the central sensor (G),while the signal of the other upfront sensor (FCS_R) is still below a first threshold value (th1) with respect to the signal of the central sensor (G), and in addition the signal of the upfront sensor (FCS_L), which exceeds the second threshold (th2) with respect to the signal of the central sensor (G), also exceeds a predetermined characteristic curve (th3).

Description

[0001] The invention relates to a method for triggering occupant protection devices in a motor vehicle on the basis of the signals of at least one right and at least one left upfront sensor and the signal of at least one impact sensor arranged centrally in the vehicle according to the preamble of claim 1.

[0002] The activation of occupant protection devices in a motor vehicle based on the signals from at least one right and at least one left upfront sensor as well as the signal from at least one impact sensor arranged centrally in the vehicle has been known for decades. The signals are compared with thresholds and an impact type and severity are derived from them. A plurality of activation paths with different criteria are provided in order to meet, for example, the different impact types and requirements for the decision to activate or not activate certain occupant protection devices as well as with regard to the activation time. It is precisely due to the partial overlap in the signal behavior between activation and non-activation cases as well as the requirement for an activation decision as early as possible and thus case differentiation that leads to the plurality of activation paths and the respective optimization.Central impact sensors are generally acceleration sensors integrated into the control unit of the occupant protection system, although the use of central acceleration sensors from other control units or a sensor cluster is also conceivable. For so-called upfront sensors, i.e. sensors located at the front of the vehicle, for example, in the area of ​​the bumper, various other types of impact sensors are known, including pressure sensors for detecting collision-related pressure changes inside a cavity, such as an elastic hose.

[0003] EP 1 028 039 A2, for example, describes an occupant safety system activation control device for controlling activation of the occupant safety system mounted on a vehicle in the event that the vehicle collides with an obstacle. The activation control device comprises a plurality of upfront sensors, i.e., impact detection means, placed at several different positions in a front portion of the vehicle. Furthermore, collision type identification means for identifying a collision type of the vehicle based on values ​​detected by the plurality of impact detection means are already known. The collision type identification means identifies the collision type as an oblique collision if, after the vehicle collision, there is a time difference between increases in the values ​​detected by the right and left impact detection means.

[0004] EP 2 504 201 A1 proposes a method for detecting the width of an impact zone of an object in the front area of ​​a vehicle. The method comprises a step of receiving a first deformation element signal, which represents a change in the distance between components of a first deformation element installed in the left front area of ​​the vehicle. Furthermore, the method comprises a step of obtaining a second deformation element signal, which represents a change in the distance between components of a second deformation element installed in the right front area of ​​the vehicle. Ultimately, these two deformation elements, with their corresponding sensors, also represent an embodiment of upfront sensors.

[0005] An offset collision with a small width of an impact area of ​​the object on the vehicle is detected if the first deformation element signal differs from the second deformation element signal by more than a predefined threshold level.

[0006] DE 11 2005 000 075 B4 describes a device for activating an occupant protection device of a vehicle, comprising a first acceleration sensor and a second acceleration sensor, each arranged inside the vehicle and each detecting an acceleration inside the vehicle, as well as an acceleration detection device arranged at the front of the vehicle for detecting an acceleration of the front end of the vehicle, wherein the acceleration detection device arranged at the front comprises acceleration sensors which are arranged on the left and right sides of the front of the vehicle.

[0007] DE 197 51 336 A1 describes a method for controlling a passive vehicle occupant safety device mounted on a vehicle, in which, when an impact occurs on the vehicle, the value of the impact is measured at a first location in the vehicle, a value calculated from the impact measurement value being compared with a threshold value which changes according to a specific threshold value change scheme, and the switching on of the passive vehicle occupant safety device being controlled according to the comparison result.When the impact occurs on the vehicle, it is determined whether an impact value detected in the vehicle at a second location ahead of the first location is not less than a certain reference value, and if it is determined that the impact value detected at the second location is not less than the certain reference value, the threshold value change scheme is switched to another threshold value change scheme.

[0008] DE 10 2017 102 751 B4 describes an activation control method for at least one occupant protection device of a vehicle, wherein a first lateral acceleration is detected by a front left sensor mounted on a front left-hand side portion of the vehicle, wherein a second lateral acceleration is detected by a front right sensor mounted on a front right-hand side portion of the vehicle, and wherein a first movement amount and a second movement amount are calculated based on the detected first lateral acceleration and based on the detected second lateral acceleration.

[0009] Subsequently, it is determined to which area on a locus a point defined by the first movement amount and the second movement amount belongs, out of areas each defined in advance for a respective collision shape, to thereby specify that the collision shape is a collision shape corresponding to the area to which the point on the locus belongs. An activation condition is then set in accordance with the specified collision shape. If the activation condition corresponds to a predetermined activation condition, the at least one occupant protection device is activated.

[0010] DE 102 23 522 A1 describes a collision shape decision device comprising left and right acceleration sensors arranged on the left and right front sides of a vehicle, respectively, for detecting accelerations at the left and right front sides, and an average calculation unit for calculating an average value based on the accelerations detected by the left and right acceleration sensors. The collision shape decision device further comprises a decision unit for comparing the average with a threshold value and for deciding, based on the comparison, whether a collision shape of the vehicle is symmetrical or asymmetrical.

[0011] DE 199 36 819 B4 describes a collision detection device for a vehicle, comprising a left-side acceleration sensor and a right-side acceleration sensor arranged opposite each other on a left and right side of a vehicle, and a collision decision device connected to an acceleration sensor arranged inside the vehicle for comparing an output signal of the acceleration sensor with a reference level to decide whether a collision of the vehicle has occurred.The collision detection device further comprises a collision type identification device having a detector connected to the left-side acceleration sensor and the right-side acceleration sensor for detecting a difference between collision signals output by the left-side acceleration sensor and the right-side acceleration sensor, and a comparison device for comparing an output signal of the detector with a threshold value to identify different collision types according to a symmetric or asymmetric collision. The collision type identification device switches the reference level for deciding whether a collision has occurred between a first level and a second level according to the identified collision type.

[0012] The object of the present invention is to further increase road safety and to present a method that enables the early and simultaneously safe activation of certain selected occupant protection devices in certain angled impact events of appropriate severity, without simultaneously addressing typical non-deployment cases or known overall deployment cases. Angled impact events with high collision energy, i.e., high relative speed between the colliding objects, require a very special optimization of the protective effect of certain occupant protection devices, i.e., their early deployment as defined in the previously known crash scenarios or deployment paths.

[0013] Of course, such high-energy oblique impact events generally lead to the overall activation of all occupant protection devices as the crash progresses, but the current activation paths and criteria are not suitable for the required, particularly early activation decision for specific occupant protection devices. This problem is solved by the features of the independent claims. Advantageous developments of the invention emerge from the subclaims, whereby combinations and developments of individual features are also conceivable.

[0014] A key concept of the invention is that the signals of the two upfront sensors are evaluated in relation to the signal of the central sensor, and at the same time, this relationship is also evaluated in relation to the two upfront sensors. In the triggering path according to the invention, a predetermined selection of occupant protection devices is therefore triggered early if the signal of one of the two upfront sensors already exceeds a second threshold value with respect to the signal of the central sensor, while the signal of the other upfront sensor is still below a first threshold value with respect to the signal of the central sensor, and the signal of the upfront sensor, which exceeds the second threshold with respect to the signal of the central sensor, also exceeds a predetermined characteristic curve.It should be pointed out again that there are usually a number of other trigger paths and the threshold values ​​there are different and then become active for other trigger cases.

[0015] Preferably, the predetermined characteristic curve has at least a first section, as long as the signal from the central sensor is at least smaller than a predetermined limit value, and triggering occurs in this section if one of the two upfront sensors exceeds the second threshold while the other upfront sensor is still below the first threshold and otherwise no triggering occurs in this section via this triggering path and this section. In addition, at least one further section is provided in which triggering via this triggering path is suppressed as soon as the signal from the central sensor is greater than a predetermined limit value.

[0016] The reason for this restriction is that, once a crash severity reaches a certain level, selective, early activation of these specific occupant protection devices is no longer necessary and, on the other hand, there is a risk that the signals themselves would otherwise also be triggered in various other impact situations.

[0017] In a further development, in addition to the two sections, a further, middle section is provided, in which the second threshold value for the upfront sensor also increases with the value for the central sensor, from which a triggering occurs, so that the two sections are essentially merged into one another via this middle section.

[0018] Preferably, the signal from the two upfront sensors is integrated using a short-term integral, while the signal from the central sensor is subjected to a double integration, and the resulting signals are evaluated relative to each other. While this might not be expected from a purely physical perspective, this unequal treatment is advantageous for crash detection in this case.

[0019] The method is preferably used to trigger a first of a plurality of stages of a driver and / or passenger airbag as well as a side or window airbag on the side on which the upfront sensor shows the correspondingly large signal.

[0020] Accordingly, a control unit for occupant protection devices has corresponding connections for the occupant protection devices, as well as connections for the signals from at least two upfront sensors and at least one central impact sensor, as well as a memory containing an algorithm for implementing the method according to the invention. Of course, additional triggering paths are also implemented in the algorithm.

[0021] The invention will be explained in more detail below using exemplary embodiments with reference to the figures. Fig. 1A shows a known design of an occupant protection system for a motor vehicle, comprising a central control unit for occupant protection devices (ACU) and integrated with at least one impact sensor G, an upfront sensor FCS_R arranged on the right side, and an upfront sensor FCS_L arranged on the left side with respect to the direction of travel. In addition to these, further sensors may be installed in the front area, side area, or centrally in the vehicle, in particular having sensitivity axes other than those directed solely in the direction of travel. However, for the method relevant here, reference is made to their signal component in the direction of travel.

[0022] The various occupant protection devices in the vehicle are not shown for the sake of simplicity, but are known from the state of the art. Fig. 1A sketched an oblique impact with 90km / h (=kph) visualized, for which the Fig. 2 and Fig. 3 also show the corresponding signal curves below. Fig. Figure 1B shows in more detail the relevant crash test setup of a so-called oblique test, which, from a certain strength onwards, particularly early activates the airbags that protect the body, especially the head, from the sides, for example side, window or so-called curtain airbags.

[0023] The Fig. 1C, however, shows a so-called SOT Small Overlap Test, for which Fig. 4 the signal curve is explained.

[0024] The Fig. 1D, however, shows a so-called ODB Offset Deformable Barrier Test, i.e. a deformable barrier that is only partially hit and for which Fig. 5 the signal curve is explained.

[0025] The Fig. 1E, however, shows a different form of oblique impact and for which Fig. 6 the signal curve is explained.

[0026] The Fig. Figures 2A to 2C now outline the signal curves of the two upfront sensors FCS_L and FCS_R, as well as the double integral value X derived from the central impact sensor G in the central airbag control unit ACU, for the very early and short time window of 0 to 35 ms from the start of the collision during a particularly critical oblique test. However, as already described at the beginning, the signals are not compared with a threshold in relation to time, but are evaluated in relation to the signal from the central impact sensor. Therefore, the Fig. 2D and Fig. 2E plotted on the X-axis is the value X of the double integral of the central impact sensor and on the Y-axis is the value of the short-term integral of the respective upfront sensors. The signal curve thus changes with respect to the signal of the central impact sensor. Fig. 2A to 2E serve purely to clarify and visualize the derivation of this synopsis from the respective temporal courses of the sensor signals based on this impact event.

[0027] The Fig. 3A to 3D now illustrate the evaluation of this synopsis, whereby the Fig. 3A and Fig. 3C shows the short-term integral of the signal of the left upfront sensor FCS_L and the Fig. 3B and Fig. 3D the course of the short-time integral of the signal of the right upfront sensor FCS_R.

[0028] The Fig. 3A and Fig. 3B illustrate the evaluation with regard to the offset characteristic with the 1st and 2nd threshold values ​​th1 < th2, whereby for the side affected by the impact, in this case the left, the 2nd, i.e. higher threshold value th2 (shown in the figures with a dash-dot-dash line) must be exceeded, while on the opposite side, in this case the right side, the signal is still below a first threshold value th1 (shown in the figures with a dashed line). For the sake of clarity, Fig. 3A and Fig. 3B shows only the appropriate threshold in each case – functionally, of course, but the signals are always evaluated in parallel against all thresholds. Even the second threshold is very low, but it is very early in relation to the signal from the central sensor G, i.e., the ACU X signal, which again indicates the particular severity of the crash.

[0029] In the preferred embodiment outlined here, a lower limit Xmin and an upper limit Xmax are also applied for this triggering path. The lower limit Xmin is intended to compensate for or eliminate the signal fluctuations, which are sometimes physically difficult to explain, especially at the onset of impact, and to prevent false triggering.

[0030] The upper limit Xmax, on the other hand, limits the application of this trigger path to the special oblique impact cases of particular severity. Fig. 3A and Fig. 3B can be understood as offset mapping, although this alone is not sufficient for case differentiation and the further criterion for the purpose of evaluation regarding the demarcation with regard to the severity of the oblique impact and in relation to other offset cases is included in the separate Fig. 3C and Fig. 3D sketched.

[0031] For the activation of these particular occupant protection devices, which are to be triggered particularly early, the signal from the upfront sensor that is directly affected by the impact (here FCS_L in the case according to the Fig. 1-3 namely, with respect to the signal of the central sensor (G), exceeds the second threshold (th2) and also exceeds a predetermined characteristic curve (th3).

[0032] The specified characteristic curve (th3) delimits a triggering area, which is also filled with dots, from the remaining non-triggering area expressly and exclusively for this triggering path, i.e., correspondingly large signals at the central sensor would naturally also lead to triggering or even total triggering of the entire occupant protection system later in the crash, but the characteristic curve specified here is optimized for the particularly early triggering of these severe angled impact collisions. This characteristic curve th3 has this preferred design of the first section (th3.1), as long as the signal from the central sensor (G) is at least smaller than a specified limit value (2.5) and in this section th3.1, triggering occurs when one of the two upfront sensors (FCS_L) also exceeds the characteristic curve th3. For the sake of completeness, it should be clarified again that all three criteria must of course be met, i.e.in addition to the characteristic curve th3, the affected upfront sensor (FCS_L) must also exceed the second threshold (th2), while the other upfront sensor (FCS_R) is still below the first threshold (th1) and otherwise no triggering occurs in this section (th3.1) via this triggering path and this section (th3.1) - as in relation to the . Fig. 3A and Fig. 3B has already been explained in advance and has been drawn apart in the figures here purely for the sake of clarity.

[0033] In this embodiment, at least one further section (th3.3) is provided, in which the triggering via this triggering path is suppressed as soon as the signal of the central sensor (G) is greater than a predetermined limit value. In addition, the Fig. 3C and Fig. 3D, however, in addition to the two sections, there is another, middle section th3.2, in which, with increasing value for the central sensor (G), the second threshold value for the upfront sensor (FCS_L, FCS_R) also increases, from which point a triggering occurs, as the figures illustrate.

[0034] As explained previously, the Fig. 3A to 3D thus show the typical course for an oblique collision of particular severity, for which a particularly early activation of the specified selection of occupant protection devices, in particular exclusively a first of a plurality of stages of a driver and / or front passenger airbag as well as a side or window airbag on the side, and is activated precisely on the side where the upfront sensor (FCS_L) shows the correspondingly large signal. Fig. 3A the corresponding function curve F left and the exceeding of the 2nd, higher threshold value, while in Fig. 3B the signal of the right upfront sensor lies within the relevant range between Xmin and Xmax below the first threshold. In addition, Fig. 3C the function curve for the left side at a value of ACU X = 2-4 also the characteristic curve th3. The Fig. The 3D image is included purely for the sake of completeness, but is not relevant for the triggering decision in this example or for impact events. Although the specific temporal progressions and amplitude levels are derived from real simulations, they are intended only as examples and to clarify the basic function.

[0035] The following Fig. 4 ff. outline further, different crash courses for the exemplary embodiment and are intended to outline the functionality and delimitation of the triggering decision for this triggering case in more detail, but accordingly to the already explained in detail Fig. 3A to 3D. Thus, the Fig. 4A to 4D a so-called SOT 64kph, small overlap test according to Fig. 1C, i.e. a rather frontal crash with also not insignificant speed and energy, which, however, does not have the comparable component transverse to the direction of travel and thus should not be subject to this particularly sensitive triggering path. Accordingly, on the impacted side on the left, the signal curve is again above the second threshold value th2 in Fig. 4A, however, on this side of the vehicle on the left, the third characteristic curve th3 within the trigger window (dotted) is not fulfilled, even if, of course, in the later course of the crash the severity is very clear, especially at the central sensor - but then other trigger paths intervene.

[0036] In addition, the Fig. 4B and Fig. 4D again shows the atypical, by no means negligible signals on the side not actually hit here on the right, which can only be explained by indirect deformations of the vehicle front, whereby these signals are partly not included in the triggering decision due to the limitation Xmin. However, it is important to clarify again that the exceeding of the characteristic curve th3 (here in Fig. 4D) is sufficient, but the th2 would have to be triggered for this side as well, which, however, according to Fig. 4B is not the case.

[0037] The Fig. 5A to 5D show a so-called 64kph ODB = Offset Deformable Barrier Test (cf. Fig. 1D), which clearly does not meet all three criteria and is particularly clearly recognizable as a non-triggering case in all four figures, because the deformability prevents the particularly early increase in the signals. In case selection, the case in the Fig. 6A to 6D shown case of an oblique impact according to Fig. 1 E, which, despite a significantly lower speed of "only" 40 km / h, shows clearly visible deflections of the upfront sensors. Here, the right side of the vehicle is hit first, but again atypically, the opposite, i.e., left upfront sensor initially shows a deflection. However, this does not reach the second threshold th2, but does on the right side that was hit ( Fig. 6B). However, both the offset criterion regarding the undershoot of the threshold value th1 and in particular the trigger criterion th3 are not met, because in Fig. 6C the side that was not actually hit (first) even comes into the trigger area (dotted), but not with the side that also exceeds the second threshold (here on the right), ie in Fig.6D, the curve remains below the characteristic curve th3. Overall, this test clearly illustrates the interaction of the three evaluation criteria.

Claims

[1] Method for triggering occupant protection devices in a motor vehicle (1) on the basis of the signals of at least one right and at least one left upfront sensor (FCS_L, FCS_R) and the signal of at least one impact sensor (G) arranged centrally in the vehicle, wherein the signals are compared with thresholds and an impact type and impact severity are derived therefrom, wherein a plurality of trigger paths with different criteria are provided and a decision is made on the triggering of the occupant protection devices depending thereon, characterized bythat in a triggering path, an early triggering of a predetermined selection of occupant protection devices already occurs when the signal of one of the two upfront sensors (FCS_L) already exceeds a second threshold value (th2) in relation to the signal of the central sensor (G), while the signal of the other upfront sensor (FCS_R) is still below a first threshold value (th1) in relation to the signal of the central sensor (G), and in addition the signal of the upfront sensor (FCS_L), which exceeds the second threshold (th2) in relation to the signal of the central sensor (G), also exceeds a predetermined characteristic curve (th3). [2] Method according to claim 1, characterized by that the given characteristic curve (th3) has at least one first section (th3.1), as long as the signal of the central sensor (G) is at least smaller than a predetermined limit and a triggering occurs in this section if the upfront sensor (FCS_L) that exceeds the second threshold (th2) also exceeds the characteristic curve (th3.1), and at least one further section (th3.3) in which the triggering via this triggering path is suppressed as soon as the signal of the central sensor (G) is greater than a predetermined limit value. [3] Method according to claim 2, characterized by that in addition to the two sections, a further, middle section (th3.2) is provided, in which, with increasing value for the central sensor (G), the threshold value (th3.2) for the affected upfront sensor (FCS_L, FCS_R) also increases, from which point on a triggering occurs. [4] Method according to one of the preceding claims, characterized bythat the signal of the two upfront sensors (FCS_L, FCS_R) is integrated via a short-time integral, while the signal of the central sensor (G) is fed into a double integration and the signals thus obtained are evaluated in relation to each other. [5] Method according to one of the preceding claims, characterized by that the predetermined selection of occupant protection devices comprises a first of a plurality of stages of a driver and / or front passenger airbag as well as a side or window airbag on the side on which the upfront sensor (FCS_L) shows the correspondingly large signal. [6] Method according to one of the preceding claims, characterized by that a lower threshold value (Xmin) is also provided for the signal (X) of the central sensor (G), below which no triggering occurs. [7] Control unit (ACU) for occupant protection devices and connections for the signals of at least two upfront sensors (FCS_L, FCS_R) and at least one central impact sensor (G) and with a memory which contains an algorithm for carrying out the method according to one of the preceding claims. [8] Motor vehicle with occupant protection devices, at least two upfront sensors (FCS_L, FCS_R) and at least one central impact sensor (G) and a control unit (ACU) with an algorithm for carrying out the method according to one of claims 1 to 6.

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