Collision detection method in a road vehicle and vehicle device designed according to the method

Abstract

Collision detection method in a road vehicle (10), comprising: (a) measuring (40) the lateral acceleration, the longitudinal acceleration and the yaw rate during operation of the vehicle (10), the lateral and longitudinal acceleration defining a total acceleration; (b) detecting (41) the occurrence of an impact by comparing a total acceleration with an impact threshold; (c) determining (42) an impact angle according to an arctangent of a ratio of the lateral and longitudinal acceleration; (d) determining a center of gravity-to-impact distance according to a mass of the vehicle (10), a moment of inertia of the vehicle (10), the measured accelerations and the yaw rate; and (e) if the yaw rate is less than a yaw threshold and the impact angle is within a predetermined range of an integer multiple of 90°, determining (44) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration, otherwise determining (48, 49) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration and a sign of the yaw rate.

Description

GENERAL STATE OF THE ART

[0001] The present invention relates generally to collision detection in motor vehicles and, more particularly, to detecting the direction of the trajectory of an impacting body at the point of impact with a host vehicle and the position on the host vehicle of that point of impact.

[0002] In particular, the invention relates to a collision detection method in a road vehicle and a vehicle device designed to carry out this method, according to the features of the independent patent claims.

[0003] Vehicle collision detection is a well-developed technology in the context of passive restraint systems that deploy in a collision to protect vehicle occupants. Specialized sensors and robust detection algorithms provide high reliability in detecting the onset of a collision that is sufficiently severe to automatically activate a passive restraint.

[0004] A typical collision detection system, for example, may consist of an array of accelerometers. Longitudinal and lateral acceleration sensor signals from the accelerometers may be generated in or communicated to a Restraints Control Module (RCM), which makes a deployment decision. Accelerometers mounted in the RCM have detection ranges of approximately -50 g to approximately +50 g. Satellite accelerometers remotely located in the front and sides of the vehicle typically have ranges of approximately -250 g to approximately +250 g. Light to moderate impacts involving lower levels of acceleration cannot be reliably detected using the existing accelerometers. However, it would be advantageous to have a means of detecting light impacts, i.e.when the severity of the impact is less than the severity used by the RCM module to initiate restraint deployment.

[0005] Even if minor vehicle-to-vehicle impacts do not directly result in significant injury to the driver or passenger, they could trigger a chain of post-impact effects that may lead to undesirable outcomes, such as further impacts or rollover events. Accordingly, detecting and recording the occurrence of minor impact collisions may be of interest to vehicle owners, fleet operators, law enforcement personnel, and insurance providers. This invention discloses techniques and systems for detecting minor impacts to enable many different types of response, such as modified vehicle control, real-time alerting of third parties (e.g., insurance, fleet, and law enforcement), and recording / storing incident information on the vehicle for later use by fleet operators and law enforcement for accident reconstruction.

[0006] When an impact occurs, it would be useful to automatically determine in real time not only the fact that an impact occurred, but also an impact direction and the position along the vehicle's outer perimeter where the impact occurred. This information can be useful not only for reporting incident details for accident reconstruction by accident investigators, but also for real-time control of vehicle systems, including, for example, adjusting or preparing passive restraint systems to deploy in a manner consistent with an evolving situation or adjusting the performance of powertrain systems to maintain vehicle control and stability.

[0007] DE 10 2010 027 969 B4 describes a method and a device for determining the type of impact of an object on a vehicle, in which rotational components arising during the impact are also taken into account in order to predict a potential risk of injury.

[0008] From DE 10 2009 046 337 A1 or DE 10 2011 085 843 A1 it is generally known to use yaw rate sensor signals in addition to longitudinal acceleration sensor signals for the detection and evaluation of an impact event.

[0009] The object of the present invention is to enable particularly precise impact detection, including detection of the impact position - especially even in the case of minor impact events.

[0010] The above-mentioned object is achieved by means of a method and a vehicle device according to the features of the independent patent claims.

[0011] Advantageous embodiments of the invention are explained in the dependent patent claims. SUMMARY OF THE INVENTION

[0012] In one aspect of the invention, a technique for collision detection in a road vehicle is provided, including determining the position of an impact along an outer perimeter of the vehicle. The lateral acceleration, the longitudinal acceleration, and the yaw rate are measured during operation of the vehicle, the lateral and longitudinal accelerations defining a total acceleration. The occurrence of an impact is detected by comparing a total acceleration to an impact threshold. An impact angle is determined according to an arctangent of a ratio of the lateral and longitudinal accelerations. A center-of-gravity-to-impact distance is determined according to a mass of the vehicle, a moment of inertia of the vehicle, the measured accelerations, and the yaw rate.If the yaw rate is zero or less than a calibrated value and the impact angle is within a predetermined range of an integer multiple of 90°, the impact position is determined in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration. Otherwise, the impact position is determined in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration and a sign of the yaw rate. As used herein, impact position typically means the coordinates (relative to the vehicle's center of gravity) on the circumference of the vehicle at which an impacting body impacts the vehicle (relative to the impacting object's center of gravity). BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a vehicle having an impact detection and recording system according to the invention. Fig. Figure 2 is a diagram showing a vehicle center of gravity, impact point, and impact distance. Fig. Figure 3 shows relationships between lateral acceleration, longitudinal acceleration, total acceleration and impact direction. Fig. Figure 4 is a diagram showing quadrants useful for illustrating an impact direction. The Fig. Figures 5-7 are diagrams showing definitions for representing different dimensions of a vehicle. Fig. Figure 8 shows a special case for determining an impact position when the yaw rate is low and the impact direction is perpendicular or nearly perpendicular. Fig. 9 is a diagram showing a distance from a center of gravity to an impact location or direction. Fig. Figure 10 is a diagram showing a combination of impact direction and center of gravity for impact distance. Fig. 11 is a diagram showing the combination in Fig. 10 matching possible impact positions. Fig. Figure 12 shows a relationship between the sign of the yaw rate and possible impact positions consistent with the yaw rate. Fig. Figure 13 shows geometric projections based on an impact angle. Fig. 14 is a flowchart showing a preferred method according to the invention. Fig. 15 is a decision tree for identifying coordinates of an impact position in the special case of Fig. 8. Fig. Figure 16 is a decision tree for identifying coordinates of an impact position in a southwest quadrant when the yaw rate is near zero. Fig. Figure 17 is a decision tree for identifying coordinates of an impact position in a southwest quadrant when the yaw rate is positive. Fig. Figure 18 is a decision tree for identifying coordinates of an impact position in a southwest quadrant when the yaw rate is negative. Fig. Figure 19 is a decision tree for identifying coordinates of an impact position in a northwest quadrant when the yaw rate is near zero. Fig. Figure 20 is a decision tree for identifying coordinates of an impact position in a northwest quadrant when the yaw rate is negative. Fig. Figure 21 is a decision tree for identifying coordinates of an impact position in a northwest quadrant when the yaw rate is positive. Fig. Figure 22 is a decision tree for identifying coordinates of an impact position in a northeast quadrant when the yaw rate is near zero. Fig. Figure 23 is a decision tree for identifying coordinates of an impact position in a northeast quadrant when the yaw rate is positive. Fig. Figure 24 is a decision tree for identifying coordinates of an impact position in a northeast quadrant when the yaw rate is negative. Fig. Figure 25 is a decision tree for identifying coordinates of an impact position in a southeast quadrant when the yaw rate is near zero. Fig. Figure 26 is a decision tree for identifying coordinates of an impact position in a southeast quadrant when the yaw rate is negative. Fig. Figure 27 is a decision tree for identifying coordinates of an impact position in a southeast quadrant when the yaw rate is positive. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0013] With reference to Fig. 1, a vehicle 10 (such as a gasoline, electric, or hybrid automobile or truck) includes a control network 11 comprising various control modules, sensors, and a multiplexed bus 12 (e.g., a CAN bus) for transmitting data signals between the various modules and sensors. Control modules that may be involved in the practice of the present invention include a Restraints Control Module (RCM) 13 with associated sensors 14, such as accelerometers. The passive restraint system would also include actuators, such as airbags (not shown), disposed throughout the vehicle 10 and connected to the RCM 13.

[0014] A body control module (BCM) 15, coupled to bus 12, is typically present in the vehicle's electrical architecture for performing general vehicle functions. The BCM 15 represents an advantageous location for implementing the inventive light impact detection. The control network 11 further includes a powertrain controller, shown in this embodiment as an engine control module (ECM) 16, coupled to various powertrain sensors 17, such as a speed sensor. The vehicle may also include a traction control module consisting of an anti-lock braking system (ABS) module 18 connected to associated sensors, such as wheel speed sensors.

[0015] The BCM 15 may include or be coupled to a non-volatile memory or storage 20 for use in connection with collision detection and reporting. For the purpose of accessing remote data and reporting impact events in real time to remote systems (e.g., law enforcement or insurance companies), a wireless communications module 21 may also be connected to the bus 12 to cooperate with the BCM 15. An antenna 22 is connected to the wireless communications module 21 to establish a data communications channel (e.g., a cellular data connection).

[0016] The purpose of the low-impact detection function is to detect, as quickly as possible, an impact that, even if not sufficiently severe to trigger a passive restraint, could produce vehicle instability or significantly change the initial kinetic energy (either rotational or linear momentum) of the vehicle. This function is not intended to trigger airbags or any other passive restraint devices. However, the sensitivity to impacts must be significantly higher than that currently used in conjunction with restraint controllers.

[0017] However, this invention is not limited to minor impact events; it is intended to detect impact positions for all types of incidents, including severe impacts. By increasing the algorithm's sampling time (i.e., by increasing the number of times the algorithm is evaluated per second using the high-speed CAN signal as input to the algorithm), the invention enables the determination of impact positions and directions for any type of event that does not involve rollover.

[0018] Impact detection may be performed as shown in co-pending U.S. application Ser. No. 83620739, entitled "Light Impact Detection for Vehicle Using Low Computation Overhead," filed concurrently herewith and incorporated herein by reference in its entirety. In summary, the light impact detection function utilizes progressive monitoring phases that can initially suspect and then confirm the occurrence of an impact. Vehicle acceleration and yaw rate are measured, and the possibility of an impact is detected using the following procedure: where a x is the longitudinal acceleration, a y is the lateral acceleration, z is a time index, where the times z 1 , e.g. 2 and z 3 are consecutive samples taken at a time step interval ΔT, and where z 2the current sample is and z 1 is the previous sample, and InImpact is a flag used to capture a duration for which the condition remains true.

[0019] If the ImImpact flag remains at a value of 1 for a predetermined duration, an impact is suspected and vehicle dynamics monitoring is increased. For example, if the last three consecutive InImpact flags are 1, an Impact_Suspected flag changes from 0 to 1. In the following pseudocode, for example, 1 , e.g. 2 and z 3 the last three samples and the consecutive impact flags are InImpact[z 1 ], InImpact[z 2 ] and InImpact[z 3 ]:

[0020] If Impact_Suspected[z 3] is equal to 1, various dynamic behaviors indicative of an impact are monitored in an attempt to confirm whether or not an impact actually occurs. The dynamic behaviors may include, for example, checking for threshold levels of front and rear tire skidding, changes in longitudinal and lateral velocity, sustained excessive acceleration or yaw rate, and lane departure rate. In particular, an Impact_Confirmed flag may be set in response to the following vehicle dynamic behaviors.

[0021] A dynamic behavior is a change in the longitudinal velocity. This is determined by integrating the longitudinal velocity a x calculated as follows: LongVchange=∫0taxdt

[0022] If an impact is suspected, LongVchange is compared to a threshold SpeedChangeCalibrationl. If the condition abs(LongVchange) > SpeedChangeCalibrationl is met, the Impact_Confirmed flag changes from 0 to 1.

[0023] Another dynamic behavior is a change in lateral velocity. This is calculated by integrating the lateral velocity a y calculated: LatVchange=∫0taydt

[0024] If an impact is suspected, LatVchange is compared to a threshold SpeedChangeCalibration2. If the condition abs(LatVchange) > SpeedChangeCalibration2 is met, the Impact_Confirmed flag changes from 0 to 1.

[0025] Another dynamic behavior used to confirm an impact is the rate of sideslip due to yaw motion and lateral acceleration. This flag checks whether the front and rear tires exceed a predefined sideslip threshold. Sideslip calculations are performed using the following physically based model. First, the lateral acceleration a lateral based on the measured sensor data a y , ω z and v x calculated so that alateral=ay−ωz×vx.

[0026] Then the lateral velocity is vlateral=∫0talateraldt

[0027] The lateral velocity due to the yaw rate, ω z , is vangularFT=ω×dFT for front tires, and vangularRT=ω×dRT for rear tires.

[0028] The total lateral speeds of the front and rear tires are vlateralFT=vlateral+vangularFT for front tires, and vlateralRT=vlateral−vangularRT for rear tires.

[0029] Thus, the side slip ratios for the front tire and the rear tire are SideSlipFT=vlateralFT / vx for front tires, and SideSlipRT=vlateralRT / vx for rear tires.

[0030] Then, the impact confirmation is obtained by using the predefined thresholds, SideSlipCalibrationl and SideSlipCalibration2, of the side slip ratios for the front and rear axles.

[0031] Another dynamic behavior for confirming a collision is the lane departure acceleration threshold. Lane departure acceleration is calculated by multiplying the yaw rate and the vehicle's longitudinal velocity. If this lateral acceleration exceeds a threshold, AccelerationCalibration3, a collision is confirmed as follows:

[0032] Yet another behavior for confirming an impact is Impact Duration, where the Impact_Suspected flag is integrated over time, denoted by InImpactTime. An impact is confirmed when the Impact_Suspected flag is asserted and InImpactTime exceeds a predetermined threshold, ImpactDurationCalibration1.

[0033] If any of the above conditions are met, the value of the Impact_Confirmed flag is set to 1. Details of the impact are stored in memory (i.e., black box), and an alert can be sent to a remote system or authority (e.g., law enforcement or insurance companies). The detected impact can also be used to modify vehicle powertrain operation or modify the performance of a passive restraint system.

[0034] The present invention uses acceleration and yaw rate to geometrically identify an angle and position of an impact. As shown in Fig. 2, the vehicle 10 has a center of gravity (CG) 25, which is typically located slightly forward of the center of the vehicle 10. An impacting object 26 impacts the vehicle 10 at an impact point 27 as it travels along an impact line 28. An impact distance 29 is the shortest distance from the CG 25 to the line 28, and is denoted by d CG marked. The distance d CG can be calculated based on the dynamic reaction of the vehicle 10 to the impact using a longitudinal acceleration a x , a lateral acceleration a y and a yaw rate ω, which act on the CG 25, as in Fig. 2. In particular, by knowing the total magnitude of the acceleration and the effect that the acceleration has on the yaw rate, the "lever arm" over which the impact affects the yaw rate can be determined. In addition, the angle of the impact line can be calculated based on a ratio of the longitudinal acceleration a x and the lateral acceleration a y can be derived. Based on the distance d CG and the angle of impact, the x and y coordinates on the vehicle where the impact occurred are derived using geometry. Fig. 2 also shows a vehicle forward speed V x to.

[0035] The impact distance d CG is preferably calculated from the moment of inertia of the vehicle using the following formula: dCG=J(ω[z2]−ω[z1]t[z2]−t[z1])max[z2]2+ay[z2]2 where m is the mass of the vehicle and J is the moment of inertia around the CG 25. The impact distance is only calculated if the total acceleration exceeds a predetermined threshold, so the above calculation does not involve division by zero.

[0036] In order to reduce noise in the calculation (due to inherent noise in the acceleration and yaw rate signals received via a multiplex bus) and for a more accurate estimation of the impact distance, a recursive least squares algorithm (RLS algorithm) is preferably used when calculating the impact distance from the CG 25.

[0037] The angle of impact is preferably determined using the inverse of the ratio of the lateral and longitudinal acceleration of the vehicle, as shown below, Angle of impact: θ=tan−1|ayax| where 0≤θ≤π2. As in Fig. 3, the impact angle θ is calculated with respect to the forward direction of the vehicle (i.e., the angle between the total acceleration and the longitudinal acceleration). Since the arctangent outputs a value between 0 and π / 2 radians (i.e., 0° and 90°) regardless of the signs of the lateral and longitudinal acceleration, a final calculated impact angle further depends on these signs. In particular, the signs of the lateral and longitudinal acceleration are used to classify an impact angle according to quadrants, as in Fig. 4. A vehicle forward direction is shown above in Fig. 4. Impacts occurring at nearly perpendicular angles to the rear, left, front, or right sides of the vehicle are identified by the narrow quadrants D1, D3, D5, and D7, respectively. For convenience, these directions may also be referred to as south, west, north, and east, respectively. Intermediate impact angles fall into wider quadrants designated as the "southwest" direction (D2), the "northwest" direction (D4), the "northeast" direction (D6), and the "southeast" direction (D8).

[0038] To reduce data traffic when sending wireless collision reports via the cloud and to reduce the on-board memory usage, the reporting and storage of collision data can be used in Fig. 4 instead of the more precise impact angle calculated above. The x- and y-coordinates where the impact occurs are calculated below with a good spatial resolution. However, to save data traffic and storage requirements, an impact position can also be calculated using the ranges L1 - L16, as in Fig. 7 shown, reported / saved.

[0039] Variables used in calculating the impact position according to a preferred embodiment include the following, as shown in the figures provided: • Half width of the vehicle: d W ( Fig. 5) • Estimated impact distance from the CG: d CG ( Fig. 2) • Distance from the CG to the front and rear of the vehicle: L f L r ( Fig. 5) • Distance from the CG to the front headlight and rear tail light of the vehicle: R f , Rr ( Fig. 5) • Impact angle (between 0 and π radians): θ • Angle between a line connecting the front and rear headlights to the CG and the side of the vehicle (between 0 and π radians): ϕ f , ϕ r , ( Fig. 6) • Possible x-coordinates for impact: x 1 or x 2 • Possible y-coordinates for impact between the front end and the CG: y f1 or y f2 • Possible y-coordinates for impact between the rear end and the CG: y r1 or y r2

[0040] As a first step in determining an impact position, the invention examines a special case where the impact direction coincides with one of the secondary cardinal directions (i.e., D1, D3, D5, or D7) and a yaw rate generated by the impact is below a threshold value. The low yaw rate indicates that the impact trajectory intersects the center of gravity (i.e., generates little or no torque around the CG). Since the impact occurs at a right angle, the impact position can thus be estimated to be one of the four positions in the secondary cardinal directions from the CG, Fig. 8 at coordinates 30, 31, 32, or 33. Furthermore, the precise point can be identified based on the direction of impact, as identified by the signs of the lateral and longitudinal acceleration. For example, if the longitudinal acceleration is positive (i.e., greater than a threshold), a rear-end impact has occurred at coordinate 30. In the event that either the yaw rate is not below the threshold or the impact angle is not close to zero or 90°, additional geometric analysis is used to determine the impact location.

[0041] Fig. 9 shows a circle 34 with radius d CG to find the center of gravity using d CG , as calculated above. Since the trajectory of the impacting object forms a tangent to the circle 34 and since the impact angle θ is calculated as shown above, four potential impact trajectories 35-38 (in Fig. 10). The intersection points of the trajectories with the outer surface of the vehicle (in Fig. 11) generate potential x and y coordinates where the impact could have occurred (and the area L, if desired). The yaw rate and other factors are used to identify the actual trajectory and select the correct coordinates. For example, two potential trajectories acting from opposite sides of the center of gravity, as in Fig. 12, a yaw rate with opposite signs. Thus, the sign of the yaw rate eliminates half of the potential trajectories. Together with the signs of the lateral and longitudinal acceleration, all but one of the trajectories is eliminated.

[0042] The invention uses various geometric projections, projecting the impact distance according to the vehicle's axes / dimensions using the impact angle. The following variables represent various projections to be used in the analysis: Rfs=Rf|sin(θ−ϕf)| Rrs=Rr|sin(θ−ϕr)| Rfs+=Rf|sin(θ+ϕf)| Rrs+=Rr|sin(θ+ϕr)| Lfs=Lf|sin(θ)| Lrs=Lr|sin(θ)| dWc=dW|cos(θ)| dWs=dW|sin(θ)|

[0043] Fig. 13 shows the projections R rs and L rs which are obtained by CGonto which lines are projected at an angle θ from a rear corner of the vehicle and a rear center point of the vehicle. Specifically, the projections include distances from a center of gravity to a front of the vehicle, a rear of the vehicle, a vehicle side, and vehicle corners, and measurements for determining the projections include angles defined by lines between the vehicle side and the impact direction and between the center of gravity and the vehicle corners.

[0044] The possible coordinate positions of the impact on the vehicle are then calculated using the following derivatives. x1=|dWc−dCGsin(θ)| x2=|dWc+dCGsin(θ)| yf1=|Lfs−dCGcos(θ)| yf2=|Lfs−dCGcos(θ)| yr1=|Lrs−dCGcos(θ)| yr2=|Lrs−dCGcos(θ)|

[0045] Depending on the acceleration, yaw rate and impact direction, a coordinate and its sign (positive or negative) are selected from the above list of x and y coordinates.

[0046] Fig. Figure 14 summarizes a preferred method according to the invention. At step 40, parameters representative of the vehicle dynamics are measured, including lateral and longitudinal acceleration and yaw rate. The vehicle dynamics measurements are checked at step 41 to determine if an impact is occurring. If not, the measurements continue to be collected at step 40. If an impact is occurring, an impact angle is calculated at step 42, e.g., using the arctangent of a ratio of lateral to longitudinal acceleration. A check is made at step 43 to determine if a low yaw rate is present and if the impact occurred at a near-right angle. If so, the impact position is given at step 44 according to the signs of the lateral and longitudinal acceleration and the corresponding position coordinates on the vehicle surface positioned at a right angle to the vehicle's center of gravity.In step 45, the impact position, impact angle, and other vehicle status parameters are stored and reported (e.g., by wireless transmission to a remote crash monitoring database). The control network preferably encodes the impact data according to a position-direction-yaw code to provide low transmission overhead. In step 46, vehicle operation may optionally be adjusted (i.e., modified) with respect to the determined impact position and direction. For example, if the vehicle includes a passive restraint system for deploying a restraint to protect an occupant of the vehicle, the deployment of the restraint may be adjusted in response to the impact position (assuming that the impact severity increases to a magnitude that causes deployment).

[0047] If the special case is not detected in step 43, a geometric analysis is used to determine the impact position by first determining an impact distance d in step 47 CG is calculated. In step 48, projections of the impact distance are identified and corresponding possible values ​​of the x and y coordinates are determined. In step 49, the actual x and y values ​​are selected based on the signs of the lateral and longitudinal acceleration and the sign of the yaw rate. The thresholds used to detect the signs are defined as: ε x corresponding to the x-acceleration (a x ), ε y corresponding to the y-acceleration (a y ), ε ω corresponding to the yaw rate (ω) and ε θ according to the angle of impact (θ).

[0048] The Fig. 15-27 further limit the analysis according to all possible circumstances for the acceleration and yaw rate values.

[0049] To determine when the lateral or longitudinal acceleration or yaw rate is approximately zero, one or more threshold values ​​denoted by ε x , ε y and ε ω are characterized as calibratable numbers close to zero (e.g. ε x = 0.1). Accordingly, if the absolute value of the longitudinal acceleration a x less than the threshold ε x is (ie |a x | ≥ ε x ), the total acceleration is almost entirely lateral acceleration (i.e. D3 or D7). If the absolute value of the yaw rate ω is less than the threshold ε ω is (ie |ω| ≤ ε ω ), the impact trajectory coincides with the center of gravity (i.e. d CG ≈ 0).

[0050] Fig. Figure 15 shows the special case detected in block 50 when the yaw rate is approximately zero (i.e. |ω| ≤ ε ω) and the angle of impact is approximately 0 (as determined by the angle θ between 0 and ε θ lies) or approximately π / 2 radians (as determined by the angle θ between π / 2- ε θ and π / 2). If the special case is detected, in blocks 51-54 the quadrant (D1, D3, D5 or D7) of the total acceleration is determined according to the sign of the longitudinal or transverse direction, whichever is greater than the threshold ε x or ε y Based on the sign of the acceleration, the x and y coordinates of the impact position are calculated as in Fig. 15 shown.

[0051] If the specific case is not determined, the impact distance d CGcalculated and the geometric projections are determined based on the impact angle θ. In a preferred embodiment, the geometric analysis may preferably be organized according to the quadrant in which the overall acceleration direction occurs. Accordingly, the Fig. 16-18 the impact coordinates if the impact direction falls in quadrant D2. The Fig. 19-21 give the impact coordinates if the impact direction falls in quadrant D4. The Fig. 22-24 give the impact coordinates if the impact direction falls in quadrant D6. The Fig. 25-27 give the impact coordinates if the impact direction falls in quadrant D8.

[0052] If the acceleration falls in quadrant D2, since a x ≥ ε x and a y ≤ -ε y , a corresponding figure of the Fig. 16-18 to determine the impact coordinates based on the sign of the yaw rate ω. The sign can be positive (i.e., ω > ε ω ), negative (i.e. ω < - ε ω or none (ie |ω| ≤ ε ω ). As shown in field 55 in Fig. 16, when the acceleration is in quadrant D2 and the sign of the yaw rate is zero (|ω| ≤ ε ω ), a geometric comparison is determined based on the difference between the impact angle θ and the vehicle corner angle Φ r in fields 56, 58 and 60, whether the impact coordinates are determined according to the potential values ​​from fields 57, 59 and 61 respectively.

[0053] If the acceleration is in quadrant D2 and the sign of the yaw rate is positive (ω > ε ω ), as shown in box 62, the impact coordinates are calculated using Fig. 17. A geometric comparison between the impact angle θ and the vehicle corner angle Φr in fields 63-65 determines a selection of subsequent comparisons between the impact distance d CG and various projections shown in boxes 66-71. The results of the selected comparisons determine the impact coordinates, which are selected as the final values, as shown in Fig. 17 shown.

[0054] If the acceleration is in quadrant D2 and the sign of the yaw rate is negative (ω < -ε ω ), as shown in box 72, the impact coordinates are calculated using Fig. 18. Geometric comparisons between the impact angle θ and the vehicle corner angle Φ r are carried out in fields 73-75 (the same comparisons as in fields 66-71 in Fig. 17) and determine a selection of subsequent comparisons between the impact distance d CGand various of the projections shown. The field for which the selected comparison is true determines whether impact coordinates are selected as the final values ​​for x and y.

[0055] If the acceleration falls in quadrant D4, since a x ≤ -ε x and a y ≤ -ε y , a corresponding figure of the Fig. 19-21 to determine the impact coordinates based on the sign of the yaw rate ω. When the yaw rate is close to zero, as shown in box 80, a geometric comparison between the impact angle θ and the vehicle corner angle Φ identifies r which set of impact coordinates is selected, as shown. If the yaw rate is negative (ω < -ε ω ), as shown in box 81, the impact coordinates are calculated using Fig. 20. Geometric comparisons between the impact angle θ and the vehicle corner angle Φ rdetermine a selection of subsequent comparisons between the impact distance d CG and various of the projections, as shown. The field for which the selected comparison is true determines whether impact coordinates are selected as the final values ​​for x and y. If the sign of the yaw rate is positive (ω> ε ω ), as shown in box 82, the impact coordinates are calculated using Fig. 21. A geometric comparison between the impact angle θ and the vehicle corner angle Φ r determines a selection of subsequent comparisons between the impact distance d CG and various projections. The results of the selected comparisons determine the impact coordinates, which are selected as the final values, as shown in Fig. 21 shown.

[0056] If the acceleration falls in quadrant D6, since a x ≤ -ε x and a y ≥ ε y, a corresponding figure of the Fig. 22-24 to determine the impact coordinates based on the sign of the yaw rate ω. When the yaw rate is close to zero, as shown in box 83, a geometric comparison between the impact angle θ and the vehicle corner angle Φ identifies r which set of impact coordinates is selected, as shown. If the sign of the yaw rate is positive (ω> ε ω ), as shown in box 84, the impact coordinates are calculated using Fig. 23. A geometric comparison between the impact angle θ and the vehicle corner angle Φ r determines a selection of subsequent comparisons between the impact distance d CG and various projections. The results of the selected comparisons determine the impact coordinates, which are chosen as the final values ​​for x and y. If the yaw rate is negative (ω < -ε ω), as shown in box 85, the impact coordinates are calculated using Fig. 24. Geometric comparisons between the impact angle θ and the vehicle corner angle Φ r determine a selection of subsequent comparisons between the impact distance d CG and various of the projections, as shown. The field for which the selected comparison is true determines whether impact coordinates are selected as the final values ​​for x and y.

[0057] If the acceleration falls in quadrant D8, since a x ≥ ε x and a y ≥ ε y , a corresponding figure of the Fig. 25-27 to determine the impact coordinates based on the sign of the yaw rate ω. When the yaw rate is close to zero, as shown in box 86, a geometric comparison between the impact angle θ and the vehicle corner angle Φ identifies rwhich set of impact coordinates is selected, as shown. If the yaw rate is negative (ω < -ε ω ), as shown in box 87, the impact coordinates are calculated using Fig. 26. Geometric comparisons between the impact angle θ and the vehicle corner angle Φ r determine a selection of subsequent comparisons between the impact distance d CG and various of the projections, as shown. The field for which the selected comparison is true determines whether impact coordinates are selected as the final values ​​for x and y. If the sign of the yaw rate is positive (ω > ε ω ), as shown in box 88, the impact coordinates are calculated using Fig. 27. A geometric comparison between the impact angle θ and the vehicle corner angle Φ r determines a selection of subsequent comparisons between the impact distance d CGand various projections. The results of the selected comparisons determine the impact coordinates, which are selected as the final values, as shown in Fig. 27 shown.

Claims

A collision detection method in a road vehicle (10), comprising:(a) measuring (40) the lateral acceleration, the longitudinal acceleration, and the yaw rate during operation of the vehicle (10), the lateral and longitudinal acceleration defining a total acceleration;(b) detecting (41) the occurrence of an impact by comparing a total acceleration with an impact threshold;(c) determining (42) an impact angle according to an arctangent of a ratio of the lateral and longitudinal acceleration;(d) determining a center of gravity-to-impact distance according to a mass of the vehicle (10), a moment of inertia of the vehicle (10), the measured accelerations, and the yaw rate;and(e) if the yaw rate is less than a yaw threshold and the impact angle is within a predetermined range of an integer multiple of 90°, determining (44) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration, otherwise determining (48, 49) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration and a sign of the yaw rate; The method of claim 1, wherein the selected projection is selected from a plurality of trigonometric projections based on the angle of impact and predetermined dimensions of the vehicle (10). The method of claim 2, wherein the predetermined measurements include distances from a center of gravity to a front of the vehicle (10), a rear of the vehicle (10), a vehicle side, and vehicle corners, and wherein the predetermined measurements include angles defined by lines between the vehicle side, the center of gravity, and the vehicle corners. The method of claim 1, further comprising the steps (45): storing the impact position in non-volatile memory; and wirelessly transmitting the impact position and a plurality of vehicle status parameters to a remote crash monitoring database. The method of claim 1, wherein the vehicle (10) includes a passive restraint system for deploying a restraint to protect an occupant of the vehicle (10), the method further comprising the step of:adjusting (46) deployment of the restraint in response to the impact position. The method of claim 1, wherein the occurrence of the impact is further detected by comparing the yaw rate to a yaw threshold. A vehicle device comprising: vehicle dynamics sensors measuring lateral acceleration, longitudinal acceleration, and yaw rate, wherein the lateral and longitudinal accelerations define a total acceleration; a control network having at least one control module communicatively coupled to the dynamics sensors, the control network: a) detecting the occurrence of an impact by comparing (41) a total acceleration to an impact threshold; b) determining (42) an impact angle according to an arctangent of a ratio of the lateral and longitudinal accelerations; c) determining (47) a center of gravity-to-impact distance according to a mass of the vehicle (10), a moment of inertia of the vehicle (10), the measured accelerations, and the yaw rate;andd) if the yaw rate is less than a yaw threshold and the impact angle is within a predetermined range of an integer multiple of 90°, determining (44) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration, otherwise determining (48, 49) an impact position in response to a projection of the impact distance selected according to the signs of the lateral and longitudinal acceleration and a sign of the yaw rate; The vehicle device of claim 7, further comprising a non-volatile memory (20) for recording the impact position and data associated with the impact, including a time, a date, and a position. The vehicle device of claim 7, further comprising a passive restraint system for deploying a restraint to protect an occupant of the vehicle (10), the passive restraint system adjusting deployment of the restraint in response to the impact position. Vehicle device according to claim 7, wherein the selected projection is selected from a plurality of trigonometric projections based on the angle of impact and predetermined dimensions of the vehicle (10). Vehicle device according to claim 10, wherein the predetermined dimensions include distances from a center of gravity to a front of the vehicle (10), a rear of the vehicle (10), a vehicle side and vehicle corners, and wherein the predetermined dimensions include angles defined by the vehicle side, the center of gravity and the vehicle corners. The vehicle device of claim 7, wherein the control network further detects the occurrence of the impact by comparing the yaw rate to a yaw threshold. Vehicle device according to claim 7, further comprising a wireless transmitter (21) for wirelessly transmitting the impact position and a plurality of vehicle status parameters to a remote crash monitoring database, wherein the control network encodes the impact position according to a position-direction-yaw code to provide low transmission overhead.

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