Method and control unit for detecting the type and / or severity of a collision between a vehicle and a collision object

Abstract

Method for detecting the type and / or severity of a collision between a vehicle (1) of a first mass (m1) and a collision object (2) of a second mass (m2) in an early phase of the collision in order to trigger suitable safety measures comprising the following steps: a) Collection of environmental data of the vehicle's surroundings (1), b) Detection of the collision object (2) from the environment data, c) Extraction of at least one reference feature (4) of the collision object (2) not located in a direct collision area (5) for further observation of a relative velocity (V) r ) between reference feature (4) of the collision object (2) and vehicle (1), d) Repeated determination of a current speed (V) 1,n ) of the vehicle (1) and determining a change in the speed of the vehicle (Delta V1), e) Repeated determination of a current relative velocity (V) r,n ) between vehicle (1) and reference feature (4) and determination of a change in the speed of the collision object (Delta V r ), f) Estimation of a mass ratio (m1 / m2) effective during the collision between the mass (m1) of the vehicle (1) and the mass (m2) of the collision object (2) from the determined changes (Delta V1, Delta V r ) the speeds of vehicle (1) and collision object (2).

Description

[0001] The present invention relates to a method for detecting the type and / or severity of a collision between a vehicle, in particular a motor vehicle, and a collision object in order to trigger appropriate safety measures. In particular, the invention also relates to a control unit for estimating the absolute mass of a collision object in an early phase of a collision with a vehicle or the ratio of a vehicle's mass to a collision object's mass.

[0002] Modern motor vehicles are equipped with extensive sensors and monitoring devices aimed at increasing the safety of vehicle occupants. With the development of autonomous vehicles, which participate in road traffic without driver intervention, increasingly improved systems for collecting environmental data from the vehicle's surroundings have been and are being developed. The present invention assumes that a vehicle is equipped with extensive sensor technology and means for generating environmental data from its surroundings. These can include, in particular, video cameras, radar systems, lidar systems, and / or ultrasound systems.

[0003] Such systems are also known to be used to anticipate collisions that can no longer be avoided as early as possible, to assess their course and severity, and to trigger vehicle safety systems, such as seat belt pretensioners, seat adjustments, and / or airbags, in a timely manner when an accident occurs. With such systems, it is also common practice to classify accidents into different categories based on their severity and / or sequence, which then lead to different sequences of safety measures.

[0004] Against this background, the invention provides a method according to claim 1 for detecting the type and / or severity of a collision between a vehicle and a collision object in an early phase of the collision in order to trigger appropriate safety measures. A control unit according to claim 10 is also included in the invention.

[0005] A parameter that has previously been difficult to take into account in a collision between a vehicle and a collision object is the mass m2 of the collision object, or the ratio of mass m1 of the vehicle to mass m2 of the collision object. Knowledge of the masses involved, or the mass ratio m1 / m2, is of great importance for predicting the accident as accurately as possible. This information, based on the physical laws of (plastic) impact, can be used to make more precise predictions about the expected loads on the vehicle occupants. The advantage that arises from having an approximate knowledge of the mass of the collision object, at least in relation to the mass of the driver's own vehicle, is independent of the other circumstances of the accident, so that its application is fundamentally advantageous for all types of collisions and all directions of impact.Of particular importance in the following considerations, however, is an accident scenario involving the front end of the vehicle, for example an impact directly from the front or diagonally from the front with complete or partial overlap of the front sides of the vehicle and the collision object. The following considerations apply precisely only to a head-on collision with complete overlap, but can also be qualitatively transferred to other accident situations at different angles with different overlap. In any case, at least an estimated value for the mass m2 of the collision object or the mass ratio m1 / m2 of the vehicle and collision object can be obtained. This can be used to better assess and categorize the expected accident scenario, leading to a more targeted application of safety measures.

[0006] The described method assumes that existing systems for scanning the environment or for collecting vehicle environmental data detect and evaluate the speed and direction of the vehicle and objects relative to each other based on existing evaluation systems, so that potential collision objects can also be identified. The environmental data in step a) of the method can be collected using sensors, for example. It is possible for the described method to be carried out in a control unit that receives such environmental data via signal inputs from external sensors (located outside the control unit).

[0007] In general, the goal is of course to avoid collisions through appropriate steering and / or braking maneuvers, but this is not always possible. According to the described method, an object with which a collision is to be expected should not only be detected and located (step b), but the scanning system for acquiring environmental data should select at least one reference feature of the collision object (step c) in order to carry out further precise observations based on this feature (step d) and other subsequent steps). The detection, localization, and further observation of collision objects in the individual method steps always initially takes place in a reference system permanently assigned to the motor vehicle. This means that a relative localization of the collision object takes place starting from the motor vehicle, and thus a relative position (relative to the motor vehicle) is determined.In steps e) and d), absolute speeds are then calculated in an absolute, stationary reference system, in which the vehicle is also moving. This is done by converting the relative observations in the reference system assigned to the vehicle into the absolute reference system. This conversion can be performed using the vehicle's speed (known from step d).

[0008] The reference feature should be located in an area of ​​the collision object that can be easily observed before and during the early phase of the collision, for example, not very low on the front of the collision object. If the collision object is a vehicle, which will be the case in most cases, a suitable reference feature could be the lower side border of a windshield (beginning of the A-pillar). Many other features suitable for safe image processing can be stored in a safety system. In this way, a scanning system for recording environmental data can be focused on one or more reference features, so that the relative speed between the vehicle and the collision object can be determined by repeated distance measurements with reference to at least one reference feature. At the same time, the current speed of the vehicle can be determined from its sensors (e.g.Measurement of the wheel speed or temporal integration of measured accelerations). This means that the speed of the colliding object can be determined from the measured relative speed and the known speed of the vehicle. As soon as the vehicle and the colliding object come into contact, deformation begins on both, so that in first approximation one can physically speak of a plastic impact. The vehicle and the colliding object slow down in proportion to their masses. By measuring the relative speed even in the early phase of the collision, i.e. by repeatedly measuring the speed of the vehicle and the relative speed between the vehicle and the colliding object at known time intervals, the mass ratio between the two colliding partners can be determined with increasing precision (with each repetition of the measurements orAs the time interval between measurements increases, the accuracy of the measurement results increases. If the mass m1 of the vehicle is known, the mass m2 of the collision object can also be determined absolutely from the mass ratio. From the initial velocities of the vehicle and the collision object measured before the collision (and, if applicable, the collision angle), the expected final velocities of both collision partners at the end of the collision and thus the severity of the accident from the vehicle's perspective can be determined early in the collision. This allows suitable safety measures to be triggered in a suitable temporal sequence (or not triggered in the case of less severe accidents).Typically, in the early stages of the collision, a measure of the type and / or severity of the collision from the vehicle's perspective is determined based on the determined mass ratio, the initial speeds measured before the collision and numerous other data from the vehicle's safety system in order to trigger appropriate safety measures associated with this measure at appropriate times.

[0009] In a preferred embodiment of the method, the environmental data is obtained using at least one of the following methods: video surveillance, lidar monitoring, radar monitoring, or ultrasonic monitoring. Such monitoring systems are used individually or in combination in modern vehicles with driver assistance systems and are currently used to increase driving safety and for the early classification of expected collisions. Video systems, but also, increasingly, the other systems mentioned, are suitable for extracting reference features and measuring relative speeds. This can be achieved using image processing methods and / or, for example, measurements based on the Doppler effect.

[0010] In a preferred embodiment of the described method, this allows at least one reference feature on the potential collision object to be selected for further observation and its current relative speed to the vehicle to be repeatedly measured. In the most favorable situation for the described method, in which a potential collision object can be observed even before the collision, this allows for quite accurate predictions about the expected accident scenario.

[0011] For example, the current speed of the vehicle before and during the collision can be repeatedly determined using the vehicle's sensors for rpm, speed, acceleration, and the like. This allows the absolute speeds of both vehicles to be determined from the relative speed to the collision object and the vehicle's own speed, allowing further conclusions to be drawn from this.

[0012] In a preferred embodiment, the absolute mass m2 of the collision object is calculated from the effective mass ratio of the vehicle and the collision object, assuming an approximately known mass m1 of the vehicle. This allows the kinematics of the collision, assuming a plastic impact, to be calculated essentially according to the law of conservation of momentum and used to determine the type and / or severity of the collision. It is immediately obvious that a collision with a large object can have more serious consequences for the occupants of a vehicle than a collision with a small object. For this reason, the early determination of the mass ratio or the mass of the collision object in the early phase of the collision, before coordinated safety measures are triggered, is a significant advantage for the safety of the vehicle occupants.

[0013] Due to the fact that processing large amounts of environmental data, such as those generated when scanning a vehicle's surroundings, requires considerable computing effort, in a preferred embodiment of the method, if an impending collision is detected, data processing is concentrated on the processes important for collision processing. This means that all uses of the environmental data that are not required to detect the type and / or severity of the collision are switched off. This provides additional computing capacity for the calculations performed before and during the early phase of the collision, allowing complex tasks such as extracting and tracking reference features and calculating the deceleration of both collision partners to be performed so quickly that safety measures are triggered in a timely manner.

[0014] Preferably, the current speed of the vehicle (step d) and the determination of the current relative speed between the reference feature and the vehicle (step e) are carried out multiple times at equal intervals during the collision, with the changes in both speeds per unit of time also being determined in each case, so that each measurement provides an increasingly accurate measure of the type and / or severity of the collision from the vehicle's perspective. It should be noted that the entire observation takes place within a short period of time, usually less than a second, which is why the time intervals for the speed measurements should be in the range of a few milliseconds.

[0015] Wherever possible from a measurement perspective, it is particularly advantageous to select and observe at least two reference features on the collision object. This increases measurement accuracy and / or allows information about other collision parameters and any rotation of the collision object to be incorporated into determining the type and / or severity of the collision. For example, using the two lower ends of a vehicle's A-pillars as reference features allows the collision angle and / or rotation of the collision partners relative to each other to be determined.

[0016] To determine the type and / or severity of the collision (step g), step f) first estimates the mass ratio between the mass of the vehicle and the mass of the collision object that would be effective during the collision. Subsequently, in step h), targeted measures can be initiated based on the estimated severity of the collision.

[0017] Environmental data from the vehicle's surroundings are used in different ways or by different systems within the vehicle. If an impending collision is detected, (all or some) uses of the environmental data that are not required for detecting the type and / or severity of the collision and the resulting measures are deactivated. This serves, in particular, to provide computing capacity for the calculations to be performed before and during the early phase of the collision (described here).

[0018] The determination of the current vehicle speed and the current relative speed between the reference feature and the vehicle are preferably performed multiple times, especially at equal time intervals during the collision, with the change in both speeds per unit of time also being determined. This provides an increasingly accurate measure of the type and / or severity of the collision from the vehicle's perspective.

[0019] Preferably, in step c) at least two reference features are extracted from a collision object and observed in the subsequent steps.

[0020] This increases measurement accuracy and / or makes it possible to incorporate information about other collision parameters and any rotation of the colliding object into determining the type and / or severity of the collision. Greater measurement accuracy can be achieved, for example, by considering two or more reference features for correction. Rotation can be detected, for example, based on differences in the speeds of two reference features on a collision object.

[0021] Also described here is a control device according to claim 10. It serves to estimate the absolute mass m2 of a collision object in an early phase of a collision with a vehicle or the ratio m1 / m2 of a mass m1 of a vehicle in relation to a mass m2 of a collision object in an early phase of a collision, wherein the control device is assigned to a system in the vehicle for triggering suitable safety measures in the event of a collision,The control unit further comprises inputs for measured values ​​from at least one first measuring device for repeatedly determining the relative speed between the vehicle and the collision object before and during the early phase of the collision, and from at least one second measuring device for repeatedly determining the absolute speed of the vehicle. The control unit is designed to estimate the mass m2 of the collision object or the mass ratio m1 / m2 of the vehicle and the collision object from the change in the absolute speed of the vehicle and the relative speed to the collision object in the early phase of the collision based on the law of conservation of momentum. The particular advantages and design features presented for the described method are applicable and transferable to the described control unit.

[0022] Such a control unit is suitable as part of a motor vehicle safety system and provides important information for classifying a collision, allowing appropriate safety measures to be triggered. The second mass m2 determined by the control unit, or the ratio m1 / m2 of the masses of the motor vehicle and the collision object, are key parameters for the expected course of a collision, so that the control unit can be used to make a more accurate prediction of the expected loads on the vehicle's occupants and to determine appropriate safety measures.

[0023] The described procedure and its context are explained in more detail below using the drawing. It shows: Fig. 1: schematically a situation shortly before collision of a vehicle with a collision object and Fig. 2: an example flowchart for the process.

[0024] Fig. 1 shows a schematic representation of a constellation shortly before the collision of a motor vehicle 1 with a collision object 2. The motor vehicle 1 has the initial speed V 1,0 and the mass m1. The collision object, in this case also represented as a motor vehicle, has the initial velocity V 2,0and the mass m2. Before the collision, the two collision partners are still a certain distance apart and spatially arranged from one another. The area directly affected by a collision (which is deformed in the process) is referred to below as the collision area 5. The vehicle 1 has at least one first measuring device 3 for recording environmental data of the surroundings of the vehicle 1. This is typically a camera, an ultrasound or laser system, or a radar device. A laser scanning system is preferably used to record environmental data because, at the same time as providing data on the direction of an object, it can also provide data on the relative movement between the vehicle 1 and the collision object 2, for example by measuring the Doppler effect.

[0025] Under favorable conditions, the first measuring device 3 provides comprehensive data about a potential collision object 2 even before a collision. Within the scope of the present considerations, it is assumed that driver assistance systems or systems for autonomous driving present in the vehicle 1 can detect potential collision objects 2 at an early stage and anticipate a collision. Once a potential collision object 2 is detected, at least a first reference feature 4 on the collision object 2 is identified with the aid of the first measuring device 3 and extracted for more precise observation. Since this first reference feature 4 is to be further observed during the collision, it should not be located in the immediate collision area 5, which is the first to deform in a collision.A suitable reference feature could be, for example, the lower corner of a side edge of a windshield, a so-called A-pillar of a motor vehicle. For greater accuracy of subsequent measurements, a second reference feature 12 and further reference features can be used, depending on the performance of the data processing in the vehicle 1. In any case, the relative distance 6 between the first measuring device 3 and the first reference feature 4 (and, of course, to further reference features) can be measured quite accurately before and during a collision. This occurs before and, above all, during the collision, preferably at equal time intervals. A second measuring device 9 in the vehicle 1 allows the absolute speed of this vehicle to be measured at any time. Several different systems can also be used for this purpose. The result is the speed data V at an input 13. 1,0 , V 1,1 , V 1,2... V 1,n at times 0, 1, 2 .... n. Likewise, information about the distance 6 between the first measuring device 3 and the first reference feature 4 is available to the control unit 7 at an input 14 for environmental data. Usually, this also includes data about the relative speed V r,0 , V r,1 , V r,2 ... V R,n available or can be calculated from the chronological sequence of this data.

[0026] A key objective of the described system is to support the safety system of a vehicle 1 in assessing the severity of a collision by providing additional information so that safety measures can be triggered in a timely and appropriate manner. When assessing a collision, it is not only important to be able to estimate the geometric data of a collision course, such as impact angle, impact speed, and time of impact, but also of great importance is the mass m2 of the colliding object 2, or the ratio of the mass m1 of the vehicle 1 to the mass m2 of the colliding object 2. Assuming essentially a plastic impact, the collision partners deform in the collision area 5, and both slow down.Simply put, the mass ratio can be calculated from the difference in the loss of speed (i.e. the negative acceleration of both collision partners). Provided that the mass m1 of vehicle 1 is known, the absolute masses of both vehicles can also be calculated. However, for the course of the collision, only the ratio of the two masses is fundamentally important. As will be explained below using the relevant formulas, in the early phase of a collision, typically in the first 10 to 100 milliseconds, the loss of speed of the two collision partners 1, 2 can be used to calculate the final speed Vend of vehicle 1 and collision object 2 after the collision (in the case of a plastic impact, both have the same speed at the end), which also allows a better estimate of the expected load for the occupants of vehicle 1.Control unit 7 therefore provides data on the mass ratio of the collision partners to system 8 for triggering safety measures, allowing the course and consequences of the collision to be assessed more accurately and safety elements to be triggered appropriately. In particular, belt tensioners 10 and / or airbags 11 can be deployed, for example.

[0027] Fig. 2 illustrates the process flow in the control unit 7. From the first measuring device 3, environmental data are forwarded to the input 14 for environmental data, including data on the relative speed V r,n between vehicle 1 and collision object 2 at shortly successive times 0, 1, 2, ... n. Where V r,0the last relative speed measured before the collision, while the following speeds are measured in the early phase of the collision. Speed ​​data is forwarded from the second measuring device 9 of the vehicle 1 to the speed data input 13. This data is available for a speed determination 15, from which speeds V 1,0 , V 1,1 , V 1,2 .... V 1,n at the times 0, 1, 2 ... n are selected or calculated. From a relative speed determination 16 and the speed determination 15, the data are forwarded to an absolute speed determination 17, whereby the absolute speed V2 is the difference between the relative speed V r and velocity V1. In the absolute velocity determination 17, for each time t = 0, 1, 2 ... n, the velocity V 1,0 , V 1,1 .... V 1,nof vehicle 1 and the speed V 2,0 , V 2,1 ,....V 2,nof the collision object 2. In an acceleration determination 18, the speed differences compared to the previous time t = 0, 1, 2, ... n-1 can therefore be determined at any time t = 1, 2, ... n. If necessary, speed differences can also be determined over longer periods of time to increase measurement accuracy, or the individual calculated values ​​at the different times can be analyzed. Overall, the acceleration determination 18 results in a negative acceleration for both collision partners, so that, assuming the physical laws of a plastic (or at least partially plastic) impact, the ratio m1 / m2 of the masses involved can be estimated in a mass (ratio) determination 19.This ratio is forwarded to system 8 to trigger safety measures, allowing the mass ratio or, if the mass m1 of vehicle 1 is known, both absolute masses of the collision partners to be taken into account when considering the severity S of a collision. The calculations described are simplified according to the following formulas: V2,n=Vr,n−V1,n with time n=0,1,2…n Delta V1,n=V1,n−V1,n−1 with time n=1,2…n Delta V2,n=V2,n−V2,n−1 with time n=1,2…n m1*V1,0+m2*V2,0=(m1+m2)*Vend S=V1−Vend S=m2 / (m1+m2)*(V1,0−V2,0) with V end Final speed of both collision partners after collision Delta deceleration S Measure of the severity of a collision

[0028] The described method enables a system for triggering safety measures in a vehicle 1 with a collision object 2 to obtain data in the early phase of a collision that allows an estimation of the mass ratio between vehicle 1 and collision object 2, which enables a more accurate early estimation of the collision consequences for occupants of the vehicle 1, thereby enabling better timing and coordination of safety measures, in particular the triggering of seat adjusters, belt tensioners and / or airbags.

Claims

[1] Method for detecting the type and / or severity of a collision between a vehicle (1) of a first mass (m1) and a collision object (2) of a second mass (m2) in an early phase of the collision in order to trigger suitable safety measures, comprising the following steps: a) Recording of environmental data of the vehicle’s surroundings (1), b) Detection of the collision object (2) from the environmental data, c) Extraction of at least one reference feature (4) of the collision object (2) not located in a direct collision area (5) for further observation of a relative speed (V r ) between reference feature (4) of the collision object (2) and vehicle (1), d) Multiple consecutive determination of a current speed (V 1,n ) of the vehicle (1) and determining a change in the speed of the vehicle (Delta V1), e) Repeated successive determination of a current relative speed (V r,n ) between vehicle (1) and reference feature (4) and determining a change in the speed of the collision object (Delta V r ), f)Estimation of a mass ratio (m1 / m2) effective during the collision between the mass (m1) of the vehicle (1) and the mass (m2) of the collision object (2) from the determined changes (Delta V1, Delta V r ) of the speeds of the vehicle (1) and the collision object (2). [2] Method according to claim 1, wherein the following method steps are carried out following step f): g) Determination of a measure of the type and / or severity (S) of the collision from the point of view of the vehicle (1) based on the determined mass ratio (m1 / m2), the initial speed measured before the collision (V 1,0 ) of the vehicle (1) and the initial relative speed (V r,0) between vehicle (1) and collision object (2), (h) triggering at least one safety measure appropriate to the nature or severity of the collision at an appropriate time. [3] Method according to claim 1, wherein the environmental data of the environment are obtained by at least one of the following methods: video surveillance, lidar surveillance, radar surveillance, ultrasonic surveillance. [4] Method according to claim 1 or 2, wherein, in the case of a potential collision object (2), at least one reference feature (4) identifiable from the environmental data is selected for further observation and its current relative speed (V r,n ) to the vehicle (1) is repeatedly measured. [5] Method according to one of the preceding claims, wherein the current speed (V 1,n) of the vehicle (1) before and during a collision is repeatedly determined from sensors for rotational speed, speed, acceleration and the like present in the vehicle (1). [6] Method according to one of the preceding claims, wherein the absolute mass (m2) of the collision object (2) is also calculated from the effective mass ratio (m1 / m2) when the mass (m1) of the vehicle (1) is approximately known, whereby the kinematics of the collision, assuming a plastic impact, can be calculated essentially according to the law of conservation of momentum and can be used to determine the measure of the type and / or severity (S) of the collision. [7] Method according to one of the preceding claims, wherein environmental data of the environment are used in different ways or by different systems in the vehicle (1), wherein in the event of a detection of an impending collision, uses of the environmental data are switched off which are not required for the detection of the type and / or severity of the collision or measures resulting from the collision. [8] Method according to one of the preceding claims, wherein the determination of the current speed (V 1,n ) of the vehicle (1) and the determination of the current relative speed (V r,n ) between reference feature (4) and vehicle (1) is carried out several times at equal time intervals during the collision, whereby the change in the two speeds (Delta V1, Delta V r ) per unit of time. [9] Method according to one of the preceding claims, wherein in step c) at least two reference features (4, 12) are extracted on a collision object (2) and observed in the subsequent steps. [10] Control device (7) for estimating the absolute mass (m2) of a collision object (2) in an early phase of a collision with a vehicle (1) or the ratio (m1 / m2) of a mass (m1) of a vehicle (1) in relation to a mass (m2) of a collision object (2) in an early phase of a collision, wherein the control device (7) is assigned to a system (8) in the vehicle (1) for triggering suitable safety measures on safety elements (10, 11) in the event of a collision, wherein the control device (7) further comprises inputs (13, 14) for measured values ​​of at least one first measuring device (3) for repeatedly determining the relative speed (V r,n) between the vehicle (1) and the collision object (2) before and during the early phase of the collision and at least one second measuring device (9) for repeatedly determining the absolute speed (V 1,n ) of the vehicle (1) and wherein the control unit (7) is configured to estimate the mass (m2) of the collision object (2) or the mass ratio (m1 / m2) of the vehicle (1) and the collision object (2) from the change in the absolute speed (Delta V1) of the vehicle (1) and the relative speed (Delta V r ) to the collision object (2) in the early phase of the collision is designed on the basis of the law of conservation of momentum.

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