Method for controlling a personal protection device of a vehicle and control unit

Abstract

Method (300) for controlling a personal protection device (114) of a vehicle (100), wherein the method (300) comprises the following steps: reading (310) a relative velocity value (108) representing a relative velocity (vrel) between the vehicle (100) and an object (104), and; determining (320) a velocity reduction value (225) representing a reduction (dvego) of a velocity of the vehicle (100) upon collision of the vehicle (100) with the object (104), using the relative velocity value (108) and optionally the correction value (110);and generating (330) a control signal (112) for controlling the personal protection device (114) using the speed reduction value (225), characterized in that in the reading step (301) at least one or more correction values ​​(110) are read in, wherein a correction value represents a mass (mobj) of the object (104), and the speed reduction value (225) is determined using at least one correction value (110).

Description

Prior ArtThe invention is based on an apparatus or a method according to the preamble of the independent claims. The present invention also relates to a computer program.Occupant protection systems for vehicles are known in which information from predictive sensors of a surroundings sensor system, such as radar, lidar or camera sensors, can be used to generate a triggering decision. For example, a relative speed between a vehicle and an object can be measured with the aid of such sensors, as is shown in DE 10 2010 009 216 A1.Disclosure of the InventionAgainst this background, the approach presented here presents a method for controlling a passenger protection device of a vehicle, furthermore a control device which uses this method, and finally a corresponding computer program according to the main claims. The measures listed in the dependent claims allow advantageous refinements and improvements of the device specified in the independent claim.A method for controlling a passenger protection device of a vehicle is presented, wherein the method comprises the following steps:reading in a relative speed value representing a relative speed between the vehicle and an object, and optionally at least one of a correction value;determining a deceleration value representing a deceleration of a speed of the vehicle when the vehicle collides with the object using the relative speed value and optionally the correction value; andgenerating a drive signal for driving the occupant protection device using the speed reduction value.A personal protection device can be understood to mean, for example, a system of active, passive or integrated safety. For example, the occupant protection device can comprise restraining means such as airbags or seatbelt pretensioners, a pedestrian protection system or adaptive crash structures. The occupant protection device can furthermore be designed to automatically steer or brake the vehicle in the event of an imminent collision. A vehicle can be understood to mean a motor vehicle such as a car or truck. The object can be, for example, a further vehicle, a pedestrian or a fixed object such as a tree, a bridge pillar or a building. The relative speed value can be determined, for example, using at least one vehicle sensor of the vehicle. The vehicle sensor can be, in particular, a predictive environment sensor such as a camera, a radar sensor or an ultrasonic sensor. The environment sensor can, for example, supply, in addition to the relative speed, further information about an opposing person before a crash. Likewise, the deceleration value may also be determined using the vehicle sensor. A correction value can be understood to mean, for example, information about the mass, size or type of the further vehicle. A correction factor can be understood to mean a function of the correction value, by which the relative speed value can be multiplied in order to increase or decrease the relative speed value, for example depending on a mass of the vehicle or a mass of the object. A deceleration value may be understood to mean a difference between a speed of the vehicle before the collision and an expected speed of the vehicle after the collision. The speed reduction value can be understood to mean an expected speed reduction value insofar as it can be determined solely on the basis of predictive sensor systems before the crash. The expected speed reduction value can be used later to influence, for example, a classic airbag algorithm. The speed reduction value can be, in particular, a positive value. For example, the control signal can be generated in the generating step in order to control the occupant protection device already before the collision without using a classic crash sensor system, such as an acceleration or pressure sensor system (pretrigger). Alternatively, trigger thresholds of an acceleration- or pressure-based trigger algorithm can be adjusted by means of the speed reduction value (preset).According to one specific embodiment, in the step of reading in, a correction value, for example, in the form of information about an opposing mass or an object type, may optionally be read in. According to one specific embodiment, a correction factor is ascertained, if appropriate, using the read-in correction value.The approach presented here is based on the finding that by correcting a relative speed value, which represents a detected relative speed between a vehicle and an object, in particular by mass correction of the relative speed value, an expected speed reduction of the vehicle can be reliably and accurately determined. The ascertained speed reduction can be used as an input variable for a passenger protection device of the vehicle, for example for an acceleration- or pressure-based deployment algorithm of an airbag. The approach presented here takes into account the fact that accident encounters in the field have finite masses-in contrast to attempts in a crash hall-so that the speed reduction in the field is usually smaller than the relative speed. By means of the approach presented here, it can now be prevented, for example, that the personal protection device tends to react too sensitively in the field. A particularly precise and robust triggering behavior in the field can thus be ensured.The detection of vehicle collisions in airbag control units is generally based on information from acceleration or pressure sensors installed in the vehicle. Usually, the measured signals of these sensors are suitably processed, for example filtered or integrated, and compared against triggering thresholds in order to arrive at a triggering decision. For such algorithms, it may be difficult to discriminate between, for example, a frontal impact at low speed on a hard obstacle, i.e. a non-triggering situation, and a frontal impact at high speed on a soft obstacle, i.e. a triggering situation, because the high collision speed does not manifest itself in a higher acceleration signal in the second case due to the soft obstacle.The relative speed is generally used to adapt the height of a triggering threshold of a triggering algorithm, which can be based on acceleration or pressure signals, for example to lower it in the event of a collision with a high relative speed, in order to arrive at a triggering decision more quickly. Such algorithms are also referred to as preset algorithms.The airbag deployment algorithms, i.e. essentially the determination of the deployment thresholds, are usually designed on the basis of a series of crash hall tests. These are standardized to a large extent by law regulations and consumer tests. For example, a front configuration can be carried out with the aid of barrier tests with hard barriers and angles of 0° and 30° and with the aid of tests with deformable barriers, also called offset deformable barrier or ODB for short, for example with an overlap of 40 percent. Common to these experiments is that the barriers used are significantly heavier than the vehicles. This means that in crash tests the relative speed between the vehicle and the object and the speed reduced in the crash are approximately identical.The approach presented here now makes it possible to integrate information regarding the relative speed, which was captured by a predictive sensor such as a radar or lidar sensor or a camera of a vehicle, into a conventional algorithm in such a way that all differences between collisions in a crash hall with stationary barriers assumed to be infinitely heavy and collisions in the field with moving accident objects of a similar mass to the vehicle that are normally finally heavy can be taken into account. For example, a corresponding method can serve as the immediate basis for a so-called pretrigger system, in which triggering decisions can be made without acceleration or pressure sensors and thus possibly even before a collision occurs.According to one specific embodiment, a correction factor may be determined in the step of ascertaining using the correction value, and the relative speed value may be multiplied by the correction factor in order to ascertain the speed reduction value. A correction factor can be understood to mean a function of the correction value. For example, in the step of reading in via Car2X communication, a mass of the object can be read in as a correction value and the correction factor can be calculated accordingly therefrom. This enables a correction of the relative speed value with little computing effort.According to a further embodiment, in the step of reading in, a value representing a mass of the vehicle, a mass of the object, a type of the object, a size of the object or a coefficient of restitution or a combination of at least two of the said variables can be read in as the correction value. This enables a particularly accurate correction of the relative speed value and thus a particularly accurate determination of the speed reduction value.It is advantageous if, in the step of ascertaining, the expected speed reduction value is ascertained using the following equation:As a result, the expected speed reduction value can be determined reliably and with little computing effort as a function of the mass of the vehicle and the mass of the object. Even in the case that no correction value such as the opposing mass or the object type can be read in, a range for the expected speed reduction can still be determined using the known intrinsic mass and assuming an average opposing mass.Furthermore, in the step of ascertaining, a value which is smaller than the relative speed value can be ascertained as the speed reduction value. As a result, it is possible to avoid triggering errors of the occupant protection device, for example in the case of collisions with a high relative speed but a low speed reduction.According to a further embodiment, the method can comprise a step of changing the relative speed value in order to obtain a changed relative speed value. Here, in the step of acquiring, the speed decrease value may be acquired using the changed relative speed value. Thereby, the speed decrease value can be adjusted by changing the relative speed value.It is furthermore advantageous if, in the step of reading in, a value is read in as the correction value, which value represents at least one value read in via an interface to at least one further vehicle and, additionally or alternatively, to a database external to the vehicle. For example, the interface may be a Car2X interface. The read-in value representing the correction value can be, for example, a mass, a variable, a movement state or a type of the further vehicle. This enables a particularly accurate and reliable determination of the speed reduction value.According to a further embodiment, in the step of reading in, a sensor signal generated by at least one sensor of the vehicle can be read in. In the generating step, the control signal can be generated using the sensor signal. The sensor signal can be, in particular, a signal of a pressure or acceleration sensor or of another sensor of a classic crash sensor system.For example, in the step of generating, threshold values for processed acceleration or pressure signals can be adapted (preset) based on the expected speed reduction value. Alternatively, no signals at all from a classic crash sensor system are required for triggering (pretrigger). This embodiment can further increase the robustness of the method.Furthermore, in the step of reading in, a further correction value can be read in, wherein the further correction value can represent a rotational energy of the vehicle during the collision. Accordingly, in the step of ascertaining, the speed reduction value can be ascertained using the further correction value. As a result, the speed reduction value can be determined as a function of a portion of a kinetic energy of the vehicle that is converted into rotational energy during the collision.It is also advantageous if the control signal is generated in the step of generating in order to change at least one activation threshold value for activating the occupant protection device based on acceleration or pressure sensors (preset) or directly control occupant protection means without waiting for acceleration or pressure signals in the crash (pretrigger). This can ensure that a protective effect of the personal protection device can be developed early and completely.Furthermore, in the generating step, the drive signal may be generated when the deceleration value is within a reference value range. Additionally or alternatively, in the generating step, the drive signal can be generated if the speed reduction value is greater than a reference value. As a result, the control signal can be generated by a simple comparison of the speed reduction value with the reference value range or the reference value and thus particularly quickly. A plurality of different reference value ranges ("speed classes") are also possible, in which the activation thresholds are influenced differently.According to a further embodiment, in the generating step, the drive signal may be generated to decrease the activation threshold value when the deceleration value is greater than the reference value. This embodiment allows the activation threshold value to be lowered particularly quickly.This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control device.The approach presented here furthermore creates a control device which is designed to carry out, actuate or implement the steps of a variant of a method presented here in corresponding devices. This embodiment variant of the invention in the form of a control unit also enables the object on which the invention is based to be achieved quickly and efficiently.For this purpose, the control device can have at least one arithmetic unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading in sensor signals from the sensor or for outputting control signals to the actuator, and / or at least one communication interface for reading in or outputting data which are embedded in a communication protocol. The computing unit can be, for example, a signal processor, a microcontroller or the like, wherein the memory unit can be a flash memory, an EPROM or a magnetic memory unit. The communication interface can be designed to read in or output data wirelessly and / or in a wired manner, wherein a communication interface that can read in or output wired data can read in this data, for example electrically or optically, from a corresponding data transmission line or output it into a corresponding data transmission line.In the present case, a control device can be understood to mean an electrical device which processes sensor signals and outputs control and / or data signals as a function thereof. The control device can have an interface which can be designed as hardware and / or software. In a hardware configuration, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the control unit. However, it is also possible for the interfaces to be dedicated, integrated circuits or to consist at least partially of discrete components. In the case of a software configuration, the interfaces can be software modules which are present, for example, on a microcontroller in addition to other software modules.In an advantageous embodiment, the control unit controls a brake system, a steering system or an engine of the vehicle. For this purpose, the control device can access sensor signals such as the environmental, pressure, acceleration, steering or brake sensor signal, for example. The actuation takes place via corresponding actuators such as steering or brake actuators.A computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is also advantageous, in particular if the program product or program is executed on a computer or a device.Exemplary embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows: FIG. 1 shows a schematic illustration of a vehicle having a control device according to one exemplary embodiment; FIG. 2 shows a schematic illustration of a control unit according to an exemplary embodiment; and FIG. 3 shows a flow diagram of a method according to an exemplary embodiment.In the following description of advantageous exemplary embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the different figures and acting in a similar manner, wherein a repeated description of these elements is omitted.FIG. 1 shows a schematic illustration of a vehicle 100 having a control device 102 according to one exemplary embodiment. The vehicle 100 travels at a speed v ego behind an object, here a further vehicle 104, which has a speed v obj. Control unit 102 is connected to a surroundings sensor 106. Environment sensor 106, which may be part of a predictive sensor system of vehicle 100, is designed to sense speed v obj to ascertain a relative speed v rel between the two vehicles 100, 104 using the two speeds v obj, v ego and to transmit a relative speed value 108 representing relative speed v rel to control unit 102. Alternatively, the environment sensor can also measure the relative speed v rel directly and send it to the control unit 102. The control device 102 is designed to ascertain a speed reduction dv ego of the vehicle 100 when colliding with the further vehicle 104, using the relative speed value 108 and an optional correction value 110, for example by multiplying the relative speed value 108 by a correction factor ascertained using the correction value 110. Depending on the ascertained speed reduction dv ego control unit 102 generates a control signal 112 for controlling a passenger protection device 114 of vehicle 100. By way of example, the occupant protection device 114 in FIG. 1 comprises an airbag 116 and a belt tensioner 118.According to this exemplary embodiment, control unit 102 is designed to read correction value 110 via an interface to a vehicle-external database 120, which is connected to further vehicle 104 via a further interface. The two vehicles 100, 104 are each connected to the database 120 via a Car2X interface, for example. Alternatively, the two vehicles 100, 104 can be designed to communicate directly with one another via the interfaces. In this case, the further vehicle 104 sends, for example, vehicle information 122 relating to specific parameters characterizing the further vehicle 104, such as mass, weight, size, type or movement state, to the database 120. The database 120 is configured to generate the correction value 110 using the vehicle information 122, i.e. depending on the mass, weight, size, type or movement state of the further vehicle 104, and to transmit it to the vehicle 100. Alternatively, control unit 102 generates correction value 110 itself, for example using sensor data provided by surroundings sensor 106, which represent, for example, the mass, the size, or the type of further vehicle 104. The correction value 110 can optionally represent a coefficient of restitution k with respect to a collision of the two vehicles 100, 104. Using the correction value in the sense of information about the mass, size or type of the further vehicle 104, the control unit 102 then calculates the correction factor.Current preset algorithms generally use the relative speed as a measure for an expected speed reduction, i.e. for a speed reduction caused by an imminent collision, also referred to above as speed reduction. Based thereon, adaptation of triggering thresholds is carried out, in particular, empirically on the basis of crash hall tests.However, since the expected speed reduction depends not only on the relative speed but also on a mass distribution of the two collision partners, further features which permit conclusions about a mass of the accident partner should as far as possible also be included in the determination of the expected speed reduction. This is now possible by means of the approach described here. These further features can be detected, for example, by a predictive sensor system. A relative speed corrected by such a mass can thus be used for reliably generating an accurate evaluation time at which the occupant protection device 114 is to be triggered.For example, in the case of a sufficiently large number of and safe features which permit conclusions to be drawn about the mass of the accident sign, the expected speed reduction can be used, for example in addition to other features detected by the predictive sensor system, for the direct actuation of restraining means of the occupant protection device 114, i.e. without taking account of an acceleration and pressure sensor system. Such systems are also referred to as pretriggering systems.The present invention is explained in more detail below with reference to various exemplary embodiments.The speed reduction dv ego to be expected in a vehicle collision can be sufficiently well estimated with the aid of the pulse maintenance set in the inelastic limit case.If v ego denotes the speed and m ego denotes the mass of the vehicle 100 under consideration before the collision, v obj denotes the speed and m obj denotes the mass of the further vehicle 104 before the collision, then the pulse conservation law is in the inelastic limit caseHere, v end denotes the speed of both vehicles 100, 104 after the collision. For the speed reduction dv ego of the vehicle 100 due to the collision, the relationship results therefrom with few transformationsAccordingly, the speed reduction dv ego depends only on the relative speed v rel= v ego- v obj and the mass distribution between the two vehicles 100, 104.The speeds of the two vehicles 100, 104 are specified here with respect to a common direction, in particular in the direction of movement of the vehicle 100 under consideration. This means that oncoming accident sounds have a negative value of v obj so that v rel= v ego- v obj is greater than v ego. In contrast, in rear-end collisions, v obj >=0, so that v rel<= v is ego. The relative speed v rel takes a positive value in all cases in which the vehicles move toward each other and a collision occurs. It assumes a negative value when the vehicles move away from each other.The speed reduction dv ego is defined, for example, such that it always assumes positive values for the vehicle 100 under consideration.Depending on the mass m obj of the object with which the vehicle 100 threatens to collide, the following values result, for example, for the speed reduction dv ego:m objdv ego∞Vrel2 m ego2⁄3 v relm ego1⁄2 v rel1⁄2 m ego1⁄2 v relOnly in the case of an infinitely heavy object, for example a bridge pillar, is the relative speed v rel equal to the speed reduction dv ego. As the mass of the accident sign decreases, the speed reduction dv ego of the subject ego vehicle 100 also decreases.If, for example, the vehicle 100 runs onto the further vehicle 104 at a speed v ego of 50 km / h at the same mass at a speed v obj of 10 km / h, then v rel= 40 km / h and dv ego= 20 km / h apply. Although the value of the relative speed v rel, suggests a high accident speed with a required two-stage airbag deployment, in particular analogously to crash hall tests, this is actually only a slight accident, in which a belt tensioner deployment may be sufficient.Although the above-mentioned formula for the speed reduction dv ego is derived from the idealised limit case of a central inelastic impact, it describes the speed reduction very well even in real and not completely central collisions.Elastic components in the vehicle 100 can be taken into account, for example, by the coefficient of restitution k, wherein the following applies: k=0 in the inelastic limit case; k=1 in the elastic limit case. A further factor (1+k) can be formed from the coefficient of restitution k, which can be used to determine the speed reduction dv ego using the above-mentioned formula. The actual speed reduction for real collisions with k<<1 is thus slightly higher than in the inelastic limit case. However, nothing changes about the basic relationship with respect to the mass distribution.In non-central collisions, i.e., offset or incomplete overlap collisions, a certain portion of the kinetic energy of the vehicle 100 converts into rotational energy. The velocity reduction dv ego caused by inelastic deformation is therefore somewhat less than in the case of the central impact. However, significant differences only occur with very small overlap, such as for example with the IIHS small overlap crash. Here too, however, the fundamental mass dependence is maintained.Instead of the relative speed, the control unit 102 now uses the speed reduction dv ego as a measure for an expected speed reduction, for example as an input variable for an acceleration- or pressure-based triggering algorithm for triggering the occupant protection device 114: with a correction factor as a function of the correction value 110, which takes into account the mass ratio of the two collision partners 100, 104.Although predictive sensors usually supply values for the relative speed v rel, but not for the object mass m obj, the second essential parameter f for the expected speed reduction dv ego is not known. Depending on the exemplary embodiment, the control unit 102 ascertains the speed reduction dv ego in different ways.In a first case, no object information regarding the object, i.e. the further vehicle 104, is present. Even in the absence of direct object information, it should be noted that a predictive sensor system, such as environment sensor 106, is designed for applications such as adaptive cruise control, distance assist or emergency braking assist. This means that the predictive sensor system recognizes in particular vehicles traveling ahead, but typically no stationary objects or vehicles approaching.The normal application of an airbag deployment algorithm influenced by the predictive sensor system is therefore the collision with vehicles of similar mass.This case is taken into account, for example, by a fixed correction factor f, which is not dependent on the accident sign, in the control unit 102, and which preferably takes into account the own mass m ego of the vehicle 100,For example, for average heavy vehicles, f=0.5.For vehicles with an average weight f<0.5.For vehicles of less than average weight, f>0.5.The remaining uncertainty with respect to the object mass m obj is taken into account in the design of the airbag algorithm, for example by corresponding variation of the relative speed v rel in the application of the triggering algorithm of the control unit 102.If, for example, collisions with opposing persons between half and double the own mass are to be taken into account for an average heavy vehicle (f=0.5), a range of the expected speed reduction between 1⁄2 v rel and 2⁄3 v rel with the value 1⁄2 v rel results in the most likely case of an average heavy accident encounter. This value is used as an expected speed reduction in the control device. This means that the control device will behave somewhat more sensitively (expected speed reduction 1⁄2 v rel is higher than actual speed reduction) in accidents with crash encounter of less than average severity, and somewhat more robust (expected speed reduction 1⁄2 v rel is lower than actual speed reduction) in accidents with crash encounter of more than average severity.This uncertainty can be ensured in the application of the control unit by tolerance considerations. If, for example, a crash test test is present between two vehicles of average weight with a relative speed v rel,1 it must be taken into account that an accident with a similar speed reduction and thus similar accident severity can also be caused by a collision of the host vehicle with average mass with a vehicle with half average mass but higher relative speed v rel,2= 1,5 v rel,1. Similarly, a collision with a vehicle with double average mass and low relative speed v rel,3= 2⁄3 v rel,1 also leads to an accident of similar severity. Therefore, the relative speed of the present test is to be varied, for example, by -33% to +50% in order to correctly cover the range of possible accident partners.If the predictive sensor system also detects trucks, the limit case m obj > > m ego and thus v crash ≈ v rel should also be taken into account. Here, the control device 102 sets the factor f larger than described above. For example, for an average-weight car which is to be designed for collision partners between truck and half as heavy car, the factor f=2⁄3 with corresponding variation of the relative speed in the application.The parameter f is realized, for example, as an application parameter that is first established in the vehicle application and is stored in an rewritable memory area of the control unit 102.In a second case, the predictive sensor system is designed to transmit object information relating to the object to the control unit 102. Accordingly, the mass determination of the further vehicle 104 can be carried out with the aid of the predictive sensor system.The Car2X function makes it possible to exchange vehicle masses directly between vehicles. The challenge here is the assignment of a transmitter to a message or also the protection against signal interference or a suspect manipulation by third parties.The situation is different with sensing systems such as radar, video and lidar. The important size of the mass is not supplied directly here, but rather is determined via the bypass of an object classification. The better and more detailed the available information about the condition of the object, the better the vehicle mass m obj can be determined.For example, the predictive sensor system can detect the movement state and the vehicle dimensions of the further vehicle 104 or carry out a general assignment of the further vehicle 104 to the class "vehicle". In this case, the predictive sensor system assigns the object to specific object types, such as, for example, cars, trucks, two-wheeled vehicles, pedestrians or posts. Suitable methods are video, stereo video, lidar and radar or ultrasound with the respectively suitable evaluation methods. In this case, the control unit 102 is designed to estimate the mass of the object, i.e. of the further vehicle 104, via a suitable heuristic mapping m_estim=f(object type, height, width, length).In particular, the correction value 110 may be a value representing a mass of the object determined using high-quality image information, wherein the image information may be represented by a sensor signal of the environment sensor 106. In this case, for example, a vehicle type of the further vehicle 104 can be matched to the database 120 via intelligent image processing in order to determine the mass m obj. Certain variances due to invisible boundary conditions such as, for example, charge, engine mass or tank content can be taken into account by a corresponding adaptation of the relative speed v rel or of the correction value 110.If the predictive sensor system provides object type information such as object= car, object= truck or object= wall, the control unit 102 can include this in the determination of the correction factor f:For example, for object=wall or object=truck, the control unit 102 uses the factor f=1.In the case of object= car, the control device 102 sets the factor f as described above in accordance with the own mass m ego of the vehicle 100, for example f=1⁄3 for a car with double average weight.In the case of object=klobular, the control device 102 sets a significantly lower correction factor f, for example f=0.15.In all cases, the remaining uncertainty with respect to the object mass m obj is to be covered, for example by varying the relative speed v rel in the application. Since the object type per se already results in a restriction of the mass range, smaller variations are sufficient than in the absence of object information.In a third case, the predictive sensor system supplies information about a collision type, for example about a degree of overlap, an offset or an angle. In this case, the control device 102 corrects the expected speed reduction, if appropriate, by a further correction factor g, which takes into account the reduced speed reduction as a result of rotational collision components.In a fourth case, in which the two vehicles 100, 104 are networked together, as shown by way of example in FIG. 1, the vehicle masses can also be exchanged between the vehicles 100, 104. This information can then be used together with the relative speed v rel determined by the predictive sensor system in order to estimate the expected speed reduction dv ego exactly:Various ways of using the expected speed degradation in an airbag deployment algorithm are described below.A standard application case consists, for example, in influencing triggering thresholds on processed signals of the crash sensor system, for example an acceleration sensor system, as a function of the expected speed reduction dv ego. This can be done stepwise, for example on the basis of speed classes, or continuously.In an alternative algorithm concept, which can consist of different trigger paths linked to one another by an OR operator, control device 102 enables specific trigger paths only if expected speed reduction dv ego is in a specific reference value range. For example, very sensitive triggering paths are only enabled when the speed reduction dv ego is very high.Alternatively, control unit 102 is designed to form combined features from signals of an acceleration sensor system and expected speed reduction dv ego. These features can be further evaluated in the airbag deployment algorithm and incorporated into the deployment decision.Described below by way of example is an application methodology with which the influence of the expected speed reduction dv ego of crash hall tests can be transmitted as correctly as possible on vehicle-vehicle collisions.Ideally, a sufficient number of vehicle-vehicle collisions is available for the application of airbag triggering algorithms in combination with a predictive sensor system, in which the predictive sensor system recognizes the object vehicle and determines the relative speed v rel and the control device 102 corrects the relative speed v rel by the factor f and subsequently influences the triggering algorithm.Typically, standardized crash hall tests with stationary and infinitely heavy barriers are available for the application of airbag triggering algorithms. With respect to the use of the relative velocity v rel for determining the velocity reduction, the following difficulties arise.Firstly, crash hall barriers are generally not recognized as an object by current predictive sensors. Secondly, the correction of the relative speed v rel by the factor f, which derives from the application "finite object mass", does not apply, or only to a limited extent, to crash hall tests with barriers of "infinite".Nevertheless, crash hall tests can be used for the application of predictive systems. The basis for this is that rigid barrier crashes (the term barrier is used here as synonym for infinitely heavy object mass) can be mapped onto equivalent vehicle-vehicle collisions, which have a comparable speed reduction and a comparable damage pattern.For reasons of symmetry, it is easily understood that a rigid barrier crash with full overlap and speed v crash, which results in a speed reduction dv ego= v crash corresponds precisely to a vehicle-vehicle collision of two identical vehicles with full overlap and v ego= v crash and v obj= - v crash, i.e. v rel= 2 v crash. In general, it applies that such a barrier crash is also equivalent to a crash of vehicles of different masses with a relative speed of v rel= v crash* ( m ego+ m obj) / m obj provided that both vehicles have a similar mass-stiffness ratio.The vehicle speed of crash hall tests therefore already represents the expected speed reduction, as it results in equivalent vehicle-vehicle collisions only after a mass correction of the relative speed v rel by the factor f. This means that in application to crash hall tests, the value of the crash speed divided by correction factor f should be used as the relative speed.The uncertainty in the field with respect to the opposing mass should be ensured by varying the relative speed.FIG. 2 shows a schematic illustration of a control unit 102 according to an exemplary embodiment, for example a control unit as described above with reference to FIG. 1. The control device 102 comprises a read-in unit 210 for reading in the relative speed value 108 and the correction value 110. A determination unit 220 is connected to the read-in unit 210, which is designed to determine a speed reduction value 225 which represents the speed reduction dv ego of the vehicle when colliding with the further vehicle, using the relative speed value 108 and the correction value 110. A generation unit 230 is configured to receive the deceleration value 225 from the ascertainment unit 220 and to generate the drive signal 112 using the deceleration value 225.According to an optional exemplary embodiment, read-in unit 210 is designed to additionally read in a sensor signal 235, which represents, for example, a signal generated by a classic crash sensor system, such as an acceleration or pressure sensor system, and to transmit it to generation unit 230. Here, the generation unit 230 is configured to generate the drive signal 112 using the sensor signal 235. For example, based on the expected deceleration value, the generation unit 230 adjusts thresholds for processed acceleration or pressure signals.FIG. 3 shows a flow diagram of a method 300 according to an exemplary embodiment. Method 300 for activating a passenger protection device of a vehicle may be carried out, for example, in conjunction with a control unit described above with reference to FIGS. 1 and 2. Method 300 includes a step 310, in which the relative speed value and the correction value are read in. In a further step 320, the speed reduction value is determined using the relative speed value and the correction value, in particular for example by multiplying the relative speed value by the correction factor derived from the correction value. Finally, in a step 330, the control signal for controlling the occupant protection device is generated using the speed reduction value.Steps 310, 320, 330 may be performed continuously.If an exemplary embodiment comprises an "and / or" combination between a first feature and a second feature, this is to be read in such a way that the exemplary embodiment has both the first feature and the second feature according to one embodiment and either only the first feature or only the second feature according to a further embodiment.

Claims

Method (300) for controlling a personal protection device (114) of a vehicle (100), wherein the method (300) comprises the following steps: reading in (310) a relative speed value (108) representing a relative speed (v rel) between the vehicle (100) and an object (104), and; determining (320) a speed reduction value (225) representing a reduction (dv ego) of a speed of the vehicle (100) when the vehicle (100) collides with the object (104), using the relative speed value (108) and optionally the correction value (110); and generating (330) a control signal (112) for controlling the occupant protection device (114) using the speed reduction value (225), characterized in that at least one or more correction values (110) are read in in the step of reading in (301), wherein a correction value represents a mass (m obj) of the object (104), and the speed reduction value (225) is determined using at least the one correction value (110).Method (300) according to Claim 1, in which, in the step of ascertaining (320), a correction factor is determined and the relative speed value (108) is multiplied by the correction factor in order to ascertain the speed reduction value (225), in particular wherein the correction factor is optionally determined using the correction value (110).Method (300) according to one of the preceding claims, in which, in the step of reading in (310), a value is read in as the correction value (110), said value representing a mass (m ego) of the vehicle (100) and / or a type of the object (104) and / or a size of the object (104) and / or a coefficient of restitution (k).The method (300) of claim 3, wherein in the step of determining (320), the deceleration value (225) is determined using the equation: d v e g o = v r e l m o b j m e g o + m o b j Method (300) according to one of the preceding claims, in which in the step of ascertaining (320) a value which is smaller than the relative speed value (108) is ascertained as the speed reduction value (225).Method (300) according to one of the preceding claims, having a step of changing the relative speed value (108) in order to obtain a changed relative speed value (108), wherein in the step of ascertaining (320) the speed reduction value (225) is ascertained using the changed relative speed value (108).Method (300) according to one of the preceding claims, in which, in the step of reading in (310), a value is read in as the correction value (110), said value representing at least one value read in via an interface to at least one further vehicle (104) and / or to a database (120) external to the vehicle.Method (300) according to one of the preceding claims, in which, in the step of reading in (310), a sensor signal (235) generated by at least one sensor of the vehicle (100) is read in, wherein, in the step of generating (330), the control signal (225) is generated using the sensor signal (235).Method (300) according to one of the preceding claims, in which a further correction value (g) is read in in the step of reading in (310), wherein the further correction value (g) represents a rotational energy of the vehicle (100) in the event of the collision, wherein the speed reduction value (225) is determined using the further correction value (g) in the step of determining (320).Method (300) according to one of the preceding claims, in which, in the step of generating (330), the control signal (112) is generated in order to change at least one activation threshold value for activating the occupant protection device (114).Method (300) according to one of the preceding claims, in which, in the step of generating (330), the drive signal (112) is generated if the speed reduction value (225) is within at least one reference value range and / or is greater than at least one reference value.Method (300) according to Claims 10 and 11, in which, in the generating step (330), the drive signal (112) is generated in order to reduce the activation threshold value if the speed reduction value (225) is greater than the reference value.Method (300) according to one of the preceding claims, in which, for the application of a control unit (102) for carrying out the method (300), crash hall tests on barriers with an approximately infinitely heavy mass and crash speed v crash are used as representatives of vehicle-vehicle crashes with v rel= v crash* ( m ego+ m obj) / m obj wherein this v rel is used for the application taking into account the possible uncertainties for m obj.Control device (102) having units (210, 220, 230) which are designed to carry out and / or actuate the method (300) according to one of the preceding claims.Computer program which is designed to execute and / or control the method (300) according to one of Claims 1 to 12.A machine readable storage medium having stored thereon the computer program of claim 15.

Images