Method for activating at least one secondary function of an occupant protection system of a vehicle

Abstract

Method (100) for activating at least one secondary function (30) of an occupant protection system (3) of a vehicle (1), wherein a vertical acceleration (az) in the vehicle vertical direction (z) and a lateral acceleration (ay) in the vehicle transverse direction (y) are detected and evaluated, and a current position of the vehicle (1) is determined based on the vertical acceleration (az) or a variable derived therefrom and the first lateral acceleration (ay) or a variable derived therefrom, characterized in that a lift-off of the vehicle (1) is detected if the vertical acceleration (az) or a variable derived therefrom fulfills a predetermined first criterion (K1), and an impact of the vehicle (1) on its wheels is detected if the vertical acceleration (az) or a variable derived therefrom fulfills a predetermined second criterion (K2),wherein a first time window (ZF1) is determined between the detected lifting of the vehicle (1) and the detected impact of the vehicle (1) on its wheels, and the at least one secondary function (30) is activated if, during the first time window (ZF1), the vertical acceleration (az) or a variable derived therefrom satisfies a third criterion (K3), which represents an impact of the vehicle (1) on its roof, and / or the lateral acceleration (ay) or a variable derived therefrom satisfies a fourth criterion (K4), which represents an impact of the vehicle (1) on one side, or if the first time window (ZF1) exceeds a predetermined time period (ZD) and the detected impact of the vehicle on its wheels satisfies a predetermined fifth criterion (K5), which represents a hard impact with subsequent rest position.

Description

[0001] The invention is based on a method for activating at least one secondary function of an occupant protection system of a vehicle according to the preamble of independent patent claim 1. The invention also relates to a device which is configured to carry out the method for activating at least one secondary function of an occupant protection system of a vehicle and to a computer program for carrying out steps of the method for activating at least one secondary function of an occupant protection system of a vehicle.

[0002] Various systems for vehicle rollover detection are known from the state of the art, which can be divided into two categories. Angular rate-based approaches are used to control time-critical primary functions of an occupant protection system, such as airbag systems, restraint systems, etc. Acceleration-based approaches are generally used to cost-effectively represent and implement non-time-critical secondary functions of such an occupant protection system, such as making an emergency call, unlocking vehicle doors, shutting off a fuel supply, etc. Acceleration-based approaches known from the state of the art primarily aim to detect a stable side or roof position after a rollover. Furthermore, the vertical acceleration can be used to detect the lift-off of the vehicle in order to obtain a rough estimate of a rollover.This can lead to a false positive detection of a rollover in stressful situations, and an emergency call can be initiated even though no rollover has occurred. Furthermore, systems that not only issue an emergency call but also shut off the fuel supply upon detection of a rollover can have a more severe impact on the vehicle. Furthermore, acceleration-based approaches that aim to detect a stable end position cannot accurately detect 360° rollovers.

[0003] For example, DE 10 2008 004 307 A1 discloses a method for detecting the position of a vehicle. Data from at least one yaw rate sensor and one acceleration sensor are evaluated to determine whether the vehicle is in a roof-up position. Upon detection of a roof-up position, the vehicle is automatically unlocked.

[0004] DE 10 2008 040 295 A1 discloses a generic method for detecting a lateral and / or roof position of a vehicle. The method comprises the steps of: receiving a lateral and / or vertical value via an interface, wherein the lateral value represents a lateral acceleration and / or the vertical value represents a vertical acceleration. Detecting the roof position of the vehicle if the vertical value or a position value derived from the vertical value is, at least in one component, absolutely greater than a predetermined vertical threshold value and / or detecting the lateral position of the vehicle if a position value derived from the vertical value and the lateral value is located in a lateral position region of a state space, wherein the state space is spanned by axes with respect to a lateral and a vertical acceleration.In addition, an upright position of the vehicle is detected if the position value was in the lateral position range but is no longer in the lateral position range after a predetermined lateral position period and / or if the position value assumed a value in at least one component that was greater than the vertical threshold value, but after a predetermined roof position period, assumed a value in at least one component that is no longer greater than the vertical threshold value. Depending on the detected position of the vehicle, safety functions such as opening the door locks, controlling the vehicle's interior lighting, and / or stopping the engine can then be implemented. Disclosure of the invention

[0005] The method for activating at least one secondary function of a vehicle occupant protection system with the features of independent patent claim 1 has the advantage that a vehicle rollover that has not resulted in a final position on the roof or side, but may be a 360° rollover, can be detected using a purely acceleration-based approach. This creates the possibility of implementing cost-effective solutions for rollover detection to activate non-time-critical secondary functions, such as making an emergency call, unlocking the doors, and / or shutting off the fuel supply to minimize the risk of fire.

[0006] Embodiments of the present invention are capable of reliably and robustly detecting rapid 360° rollovers. The assumption of the invention is that ground contact will predominate at various times during a 360° rollover. This creates characteristic signal curves in the lateral and vertical acceleration directions, which can be used to verify the plausibility of the situation. By detecting a sideways position and / or a roof position before the vehicle lands back on its wheels, even slowly rotating 360° rollovers can be reliably detected. This makes it possible to achieve a high degree of detection of 360° rollovers in a robust overall solution. The core of the invention is based on the evaluation of characteristic signal curves in the lateral and vertical acceleration directions during a 360° rollover with ground contact.With this approach, even long free flight phases, in which 360° rollovers without ground contact are possible and which end with a hard impact of the vehicle on its wheels, can lead to an activation of at least one secondary function.

[0007] Embodiments of the present invention provide a method for activating at least one secondary function of an occupant protection system of a vehicle. A vertical acceleration in the vehicle's vertical direction and a lateral acceleration in the vehicle's transverse direction are detected and evaluated. Based on the vertical acceleration or a variable derived therefrom and the first lateral acceleration or a variable derived therefrom, a current position of the vehicle is determined. Lifting of the vehicle is detected if the vertical acceleration or a variable derived therefrom fulfills a predefined first criterion. An impact of the vehicle on its wheels is detected if the vertical acceleration or a variable derived therefrom fulfills a predefined second criterion.In addition, a first time window is determined between the detected lift-off of the vehicle and the detected impact of the vehicle on its wheels. The at least one secondary function is activated if, during the first time window, the vertical acceleration or a variable derived therefrom meets a third criterion, which represents an impact of the vehicle on its roof, and / or the lateral acceleration or a variable derived therefrom meets a fourth criterion, which represents an impact of the vehicle on one side, or if the first time window exceeds a predetermined time period and the detected impact of the vehicle on its wheels meets a predetermined fifth criterion, which represents a hard impact followed by a rest position.

[0008] In this context, a rest position is defined as a state of the vehicle in which it is not moving or is only moving at a constant low speed. The rest position can already be present when the vehicle is not yet completely stationary. The rest position essentially indicates that after the 360° rollover, no further rollover or tipping of the vehicle is to be expected.

[0009] Furthermore, a device is proposed which is configured to carry out the method for activating at least one secondary function of an occupant protection system of a vehicle. The device comprises a first sensor which detects a vertical acceleration in the vertical direction of the vehicle, a second sensor which detects a lateral acceleration in the transverse direction of the vehicle, and an evaluation and control unit which receives and evaluates the detected vertical acceleration and the detected lateral acceleration and determines a current position of the vehicle based on the vertical acceleration and the first lateral acceleration.

[0010] A further aspect of the invention relates to a computer program for carrying out steps of the method for activating at least one secondary function of an occupant protection system of a vehicle when the computer program is executed on a data processing system.

[0011] In this case, the evaluation and control unit can be understood to be an electrical device, such as a control unit, in particular an airbag control unit, which processes or evaluates detected sensor signals. The evaluation and control unit can have at least one interface, which can be implemented in hardware and / or software. In a hardware implementation, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the evaluation and control unit. However, it is also possible for the interfaces to be separate integrated circuits or to consist at least partially of discrete components. In a software implementation, the interfaces can be software modules, which are present, for example, on a microcontroller alongside other software modules.Also advantageous is a computer program product with program code stored on a machine-readable medium such as a semiconductor memory, a hard disk memory or an optical memory and used to carry out the evaluation when the program is executed by the evaluation and control unit.

[0012] The measures and further developments listed in the dependent claims enable advantageous improvements to the method specified in independent patent claim 1 for activating at least one secondary function of an occupant protection system of a vehicle and the device specified in independent patent claim 10 for carrying out the method.

[0013] A particularly advantageous feature is that longitudinal acceleration in the vehicle's longitudinal direction can be recorded and evaluated. This makes it possible to verify the plausibility of a detected hard impact of the vehicle on its wheels.

[0014] In an advantageous embodiment of the method, the first criterion can be met if the vertical acceleration or a value derived therefrom exceeds a predetermined first threshold value. In principle, one can speak of a vehicle lift-off if the vertical acceleration lies below a negative threshold at low frequency. The first criterion is detected by evaluating the vertical acceleration. This can be done by suitable low-pass filtering followed by a comparison against the first threshold value. If the first threshold value is exceeded, a counter can be started, for example, which is stopped when an impact of the vehicle on its wheels is detected. If the condition lasts sufficiently long and the counter exceeds a predetermined threshold, the vehicle lift-off can be detected. During the lift-off state orDuring free flight of the vehicle, the value of the detected vertical acceleration is usually a negative value, which is intended to compensate for the value of the gravitational acceleration. Therefore, the first threshold has a negative sign. Furthermore, the second criterion can be met if the vertical acceleration or a value derived from it exceeds a predetermined second threshold. In this case, the second threshold corresponds to an acceleration value that has a different sign than the acceleration value of the first threshold.

[0015] In a further advantageous embodiment of the method, the third criterion can be met and an impact of the vehicle on its roof can be detected if the vertical acceleration or a variable derived therefrom exceeds a predetermined third threshold value. The third threshold value has a different sign than the second threshold value because the direction of the acceleration acting in the event of a roof impact is opposite to the acceleration acting in the event of an impact on the wheels. If the third criterion is met, it can be remembered or stored for a predetermined period of time. The fourth criterion can be met and an impact of the vehicle on one side can be detected if the lateral acceleration or a variable derived therefrom exceeds a predetermined fourth threshold value or a predetermined fifth threshold value.The fourth and fifth thresholds have different signs, since the direction of the acceleration acting upon an impact on the right side of the vehicle is opposite to that acting upon an impact on the left side of the vehicle. If a side contact or impact on the side is detected, this can be recorded or stored for a specified period of time.

[0016] In a further advantageous embodiment of the method, the fifth criterion can be met if, based on the detected impact of the vehicle on its wheels, the vertical acceleration or a variable derived therefrom exceeds a predetermined sixth threshold value and the lateral acceleration or a variable derived therefrom exceeds a predetermined seventh threshold value within a predetermined second time window, and the vertical acceleration or a variable derived therefrom and the lateral acceleration or a variable derived therefrom show no further activity after the predetermined second time window. Liftoff can also occur without rotation as a result of a jump; therefore, the severity of the vehicle's impact on its wheels is evaluated to decide whether activation of the at least one secondary function is indicated.A hard impact is detected when the vertical acceleration has a characteristically high value and then converges towards zero during the second time window. At the same time, such a hard impact of the vehicle on its wheels also leads to an oscillating deflection of the lateral acceleration within the second time window due to the vibrations. The fifth criterion, or the hard impact of the vehicle on its wheels, can be verified by evaluating the longitudinal acceleration. The fifth criterion can be assessed as plausible if, based on the detected impact of the vehicle on its wheels within the specified second time window, the longitudinal acceleration or a value derived from it exceeds a specified eighth threshold value.The resting state after the impact of the vehicle on its wheels is recognized by the fact that the acceleration signals in the longitudinal, lateral and vertical directions show no further activity.

[0017] In a further advantageous embodiment of the method, the at least one secondary function can comprise an emergency call function and / or a door unlocking function and / or a fuel supply shut-off function.

[0018] In a further advantageous embodiment of the method, the recorded accelerations can be filtered before evaluation.

[0019] In a further advantageous embodiment of the device, a third sensor can detect the longitudinal acceleration in the vehicle's longitudinal direction, whereby the evaluation and control unit can receive and evaluate the longitudinal acceleration. Furthermore, at least one low-pass filter can filter the detected accelerations.

[0020] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In the drawings, identical reference numerals designate components or elements that perform identical or analogous functions. Short description of the drawings Fig. 1 shows a schematic representation of a vehicle with an embodiment of a device for carrying out a method according to the invention for activating at least one secondary function of an occupant protection system of a vehicle. Fig. 2 shows a schematic flow diagram of an embodiment of a method according to the invention for activating at least one secondary function of an occupant protection system of a vehicle. Fig. 3 shows a characteristic diagram with a temporal course of a vertical acceleration of a vehicle. Fig. 4 shows a characteristic diagram with a time course of a lateral acceleration of a vehicle. Embodiments of the invention

[0021] As from Fig. 1, the illustrated embodiment of a vehicle 1 comprises an occupant protection system 3, which comprises a restraint system 5, an airbag system 7 and an embodiment of a device 10 according to the invention. The device 10 is designed to Fig. 2 for activating at least one secondary function 30 of the occupant protection system 3 of the vehicle 1 and comprises a first sensor 14 which detects a vertical acceleration az in the vehicle vertical direction z, a second sensor 16 which detects a lateral acceleration ay in the vehicle transverse direction y, and an evaluation and control unit 12 which receives and evaluates the detected vertical acceleration az and the detected lateral acceleration ay and determines a current position of the vehicle 1 based on the vertical acceleration az and the lateral acceleration ay.

[0022] In the illustrated embodiment, the device 10 also has a third sensor 18, which detects a longitudinal acceleration ax in the vehicle's longitudinal direction x. The evaluation and control unit 12 receives and evaluates the longitudinal acceleration ax. Furthermore, in the illustrated embodiment, the evaluation and control unit 12 uses a low-pass filter TF, which filters the detected accelerations ax, ay, az.

[0023] As from Fig. 2 to 4, the method 100 for activating at least one secondary function 30 of the occupant protection system 3 of the vehicle 1 detects a vertical acceleration az in the vehicle's vertical direction z in a step S100 and evaluates this. In step S110, it is checked whether the vertical acceleration az or a variable derived therefrom fulfills a predetermined first criterion K1, which represents a lift-off of the vehicle 1. If the first criterion K1 is not met, the method returns to step S100. If a lift-off of the vehicle 1 is detected in step S110, a lateral acceleration ay in the vehicle's transverse direction y is detected and evaluated in step S120. In step S130, it is checked whether the vertical acceleration az or a variable derived therefrom fulfills a predetermined second criterion K2, which represents an impact of the vehicle 1 on its wheels.The check continues until the second criterion is met and an impact of vehicle 1 on its wheels has been detected. In step S140, a first time window ZF1 between the detected lift-off of vehicle 1 and the detected impact of vehicle 1 on its wheels is determined. To facilitate the determination of the first time window ZF1, after step S110 and a detected lift-off of vehicle 1, a counter or stopwatch can be started in an optional step S115, which is shown in dashed lines. After step S130 and a detected impact of vehicle 1 on its wheels, the counter or stopwatch can be stopped again in an optional step S135, which is shown in dashed lines. In step S140, the counter value representing the first time window ZF1 can then be read out.In step S150, a check is then carried out to determine whether, during the first time window ZF1, the vertical acceleration az or a variable derived therefrom has fulfilled a third criterion K3, which represents an impact of the vehicle 1 on its roof. If such a roof impact of the vehicle 1 is detected in step S150, then the at least one secondary function 30 is activated in step S190. If no roof impact is detected in step S150, then in step S160 a check is carried out to determine whether the lateral acceleration ay or a variable derived therefrom fulfills a fourth criterion K4, which represents an impact of the vehicle 1 on one side. If such a side impact of the vehicle 1 is detected in step S160, then in step S190 the at least one secondary function 30 is activated. If no side impact is detected in step S160, then in step S170 a check is carried out to determine whether the first time window ZF1 exceeds a predetermined time period ZD.If the time period ZD is not detected to be exceeded in step S170, the method returns to step S100. If the time period ZD is detected to be exceeded in step S170, a check is carried out in step S180 to determine whether the detected impact of vehicle 1 on its wheels satisfies a predetermined fifth criterion K5, which represents a hard impact followed by a rest position of vehicle 1. If the detected impact of vehicle 1 on its wheels does not meet a hard impact followed by a rest position of vehicle 1, the method returns to step S100. If the detected impact of vehicle 1 on its wheels is detected in step S180, the method returns to step S100.

[0024] The vehicle's rest position can be determined, on the one hand, via the vehicle's recorded speed (vX). This is typically available as a vehicle parameter via the vehicle communication bus, e.g., the CAN bus.

[0025] Another detection option without taking vehicle speed (vX) into account can be achieved by evaluating the acceleration signals in the X, Y, and Z directions (aX, aY, aZ). If these acceleration values ​​assume characteristic values, an end position of the vehicle on the wheels, i.e. a rest position, is assumed. The characteristic values ​​can be defined by threshold values ​​for the accelerations or by relationships between the accelerations. For example, by the values ​​for acceleration in the X and Y directions assuming a value of almost 0 g and the value for acceleration in the Z direction assuming a value of almost 1 g. In addition, the yaw rate values ​​can be evaluated, which then also assume a value of almost 0 ° / s. In order for the rest position to be reliably detected, these values ​​must be present for a predetermined time.

[0026] In addition, the evaluation of the vehicle speed (vX) can be used to improve or make the evaluation plausible based on the acceleration values ​​and, if applicable, the rotation rate.

[0027] In the illustrated embodiment, the at least one secondary function 30 comprises an emergency call function 32, a door unlocking function 34, and a fuel supply shutoff function 36. Of course, further non-time-critical secondary functions, such as switching on the interior lighting, etc., can also be provided. Furthermore, only the emergency call function 32 or the door unlocking function 34 or a fuel supply shutoff function 36 can be provided.

[0028] In addition to the lateral acceleration, a longitudinal acceleration ax in the vehicle's longitudinal direction x can be detected and evaluated in step S120. Furthermore, the detected accelerations ax, ay, az can be filtered, and the filtered acceleration values ​​can be evaluated in addition to or alternatively to the acceleration values ​​ax, ay, az.

[0029] In the illustrated embodiment, the first criterion K1 is recognized as fulfilled in step S110 if the vertical acceleration az or a variable derived therefrom exceeds a predetermined first threshold value SW1. The second criterion K2 is recognized as fulfilled in step S130 if the vertical acceleration az or a variable derived therefrom exceeds a predetermined second threshold value SW2.

[0030] In the illustrated embodiment, the third criterion K3 is fulfilled in step S150 and an impact of the vehicle 1 on its roof is detected if the vertical acceleration az or a variable derived therefrom exceeds a predetermined third threshold value (not shown). The low-pass filtered vertical acceleration az shows a large negative value when the vehicle 1 impacts its roof, which is compared with the third threshold value. Physically, the impact on the roof lasts for a certain period of time. The vertical acceleration az can be distinguished from signal peaks resulting from transient disturbances in that it lies above the third threshold value for a certain period of time. As soon as the third criterion K3 is fulfilled, the roof impact is qualified and stored.

[0031] In the illustrated embodiment, the fourth criterion K4 is deemed to be met in step S160 and an impact of the vehicle 1 on one side is detected if the lateral acceleration ay or a variable derived therefrom exceeds a predetermined fourth threshold value SW4 or a predetermined fifth threshold value (not shown). An impact of the vehicle 1 on one side manifests itself in a strong acceleration in the lateral direction y. Here, too, detection can be carried out via a low-pass filtered lateral acceleration ay. The filtered lateral acceleration ay is compared with the fourth threshold value SW4. In addition, the low-pass filtered vertical acceleration az can also be evaluated to detect the impact of the vehicle 1 on one side, which has a negative value in the case of a side impact of the vehicle 1.

[0032] In the illustrated embodiment, the fifth criterion K5 is recognized as fulfilled in step S180 if, based on the detected impact of the vehicle 1 on its wheels within a predetermined second time window ZF2, the vertical acceleration az or a variable derived therefrom exceeds a predetermined sixth threshold value SW6 and the lateral acceleration ay or a variable derived therefrom exceeds a predetermined seventh threshold value SW7 and the vertical acceleration az or a variable derived therefrom and the lateral acceleration ay or a variable derived therefrom show no further activities after the predetermined second time window ZF2.

[0033] In Fig. 3 and Fig. 4 shows schematic curves of the vertical acceleration az and the lateral acceleration ay during a 360° rollover with a side impact of vehicle 1 during the first time window ZF1. As can be seen from Fig. 4, the lateral acceleration ay or a value derived therefrom exceeds the specified fourth threshold value SW4 during the first time window ZF1. In the last phase, vehicle 1 falls with a hard impact onto its wheels. As a result, the vertical acceleration az in Fig. 3 has a characteristically high positive value, which is above the sixth threshold SW6, and then converges to zero. In addition, the hard impact of vehicle 1 on the wheels leads to a deflection of the lateral acceleration ay in Fig. 4, which is above the seventh threshold value SW7. After the impact, vehicle 1 reaches a steady-state final state after the expiration of the second time window ZF2. Therefore, the vertical acceleration az and the lateral acceleration ay show no further activity.

[0034] The fifth criterion K5 can be additionally verified for plausibility in step S180 by evaluating the longitudinal acceleration ax. The fifth criterion K5 is recognized as plausible if, based on the detected impact of vehicle 1 on its wheels within the predefined second time window ZF2, the longitudinal acceleration ax or a variable derived therefrom exceeds a predefined eighth threshold value (not shown) and shows no further activity after the predefined second time window ZF2.

[0035] This method can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example, in a control unit. The corresponding computer program for performing steps of method 100 for activating at least one secondary function 30 of an occupant protection system 3 can then be executed in such a control unit as a data processing system.

Claims

[1] Method (100) for activating at least one secondary function (30) of an occupant protection system (3) of a vehicle (1), wherein a vertical acceleration (az) in the vehicle vertical direction (z) and a lateral acceleration (ay) in the vehicle transverse direction (y) are detected and evaluated and a current position of the vehicle (1) is determined based on the vertical acceleration (az) or a variable derived therefrom and the first lateral acceleration (ay) or a variable derived therefrom, characterized bythat a lift-off of the vehicle (1) is detected when the vertical acceleration (az) or a variable derived therefrom satisfies a predetermined first criterion (K1), and an impact of the vehicle (1) on its wheels is detected when the vertical acceleration (az) or a variable derived therefrom satisfies a predetermined second criterion (K2), wherein a first time window (ZF1) is determined between the detected lift-off of the vehicle (1) and the detected impact of the vehicle (1) on its wheels and the at least one secondary function (30) is activated if, during the first time window (ZF1), the vertical acceleration (az) or a variable derived therefrom satisfies a third criterion (K3), which represents an impact of the vehicle (1) on its roof, and / or the lateral acceleration (ay) or a variable derived therefrom satisfies a fourth criterion (K4), which represents an impact of the vehicle (1) on one side,or if the first time window (ZF1) exceeds a predetermined time period (ZD) and the detected impact of the vehicle on its wheels meets a predetermined fifth criterion (K5), which represents a hard impact followed by a rest position. [2] Method (100) according to claim 1, characterized by that a longitudinal acceleration (ax) in the vehicle's longitudinal direction (x) is recorded and evaluated. [3] Method (100) according to claim 1 or 2, characterized by that the first criterion (K1) is met if the vertical acceleration (az) or a variable derived therefrom exceeds a predetermined first threshold value (SW1), wherein the second criterion (K2) is met if the vertical acceleration (az) or a variable derived therefrom exceeds a predetermined second threshold value (SW2). [4] Method (100) according to one of claims 1 to 3, characterized bythat the third criterion (K3) is met and an impact of the vehicle (1) on its roof is detected if the vertical acceleration (az) or a value derived therefrom exceeds a predetermined third threshold value. [5] Method (100) according to one of claims 1 to 4, characterized by that the fourth criterion (K4) is met and an impact of the vehicle (1) on one side is detected if the lateral acceleration (ay) or a variable derived therefrom exceeds a predetermined fourth threshold value (SW4) or a predetermined fifth threshold value. [6] Method (100) according to one of claims 1 to 5, characterized bythat the fifth criterion (K5) is met if, based on the detected impact of the vehicle (1) on its wheels within a predetermined second time window (ZF2), the vertical acceleration (az) or a variable derived therefrom exceeds a predetermined sixth threshold value (SW6) and the lateral acceleration (ay) or a variable derived therefrom exceeds a predetermined seventh threshold value (SW7) and the vertical acceleration (az) or a variable derived therefrom and the lateral acceleration (ay) or a variable derived therefrom show no further activities after the predetermined second time window (ZF2). [7] Method (100) according to claim 6, characterized bythat the fifth criterion (K5) is made plausible by evaluating the longitudinal acceleration (ax), wherein the fifth criterion (K5) is plausible if, based on the detected impact of the vehicle (1) on its wheels within the predetermined second time window (ZF2), the longitudinal acceleration (ax) or a variable derived therefrom exceeds a predetermined eighth threshold value and shows no further activities after the predetermined second time window (ZF2). [8] Method (100) according to one of claims 1 to 7, characterized by that the at least one secondary function (30) comprises an emergency call function (32) and / or a door unlocking function (34) and / or a fuel supply shut-off function (36). [9] Method (100) according to one of claims 1 to 8, characterized by that the recorded accelerations (ax, ay, az) are filtered. [10] Device (10) which is configured to carry out the method for activating at least one secondary function (30) of an occupant protection system (3) of a vehicle (1) according to at least one of claims 1 to 9, wherein the device (10) comprises a first sensor (14) which detects a vertical acceleration (az) in the vehicle vertical direction (z), a second sensor (16) which detects a lateral acceleration (ay) in the vehicle transverse direction (y), and an evaluation and control unit (12) which receives and evaluates the detected vertical acceleration (az) and the detected lateral acceleration (ay) and determines a current position of the vehicle (1) based on the vertical acceleration (az) and the first lateral acceleration (ay). [11] Device (10) according to claim 10, characterized bythat a third sensor (18) detects a longitudinal acceleration (ax) in the vehicle's longitudinal direction (x), wherein the evaluation and control unit (12) receives and evaluates the longitudinal acceleration (ax). [12] Device (10) according to claim 10 or 11, characterized by that at least one low-pass filter (TF) filters the recorded accelerations (ax, ay, az). [13] Device (10) according to one of claims 10 to 12, characterized by that the at least one secondary function (30) comprises an emergency call function (32) and / or a door unlocking function (34) and / or a fuel supply shut-off function (36). [14] Computer program for carrying out steps of the method (100) for activating at least one secondary function (30) of an occupant protection system (3) of a vehicle (1) according to at least one of claims 1 to 9, when the computer program is executed on a data processing system.

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