Method for detecting a slight impact against a vehicle and vehicle device designed according to the method

Abstract

A method for detecting a minor impact against a vehicle (10), comprising. (a) comparing a measured acceleration and a measured yaw rate with corresponding baseline threshold values ​​in a baseline state (33); (b) if the acceleration is above the corresponding base threshold, determining (34) 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 acceleration of the vehicle (10), and the measured yaw rate of the vehicle (10); (c) if the determined distance is less than a distance to a vehicle edge, transitioning to a presumed impact state (36) if at least one of the acceleration and the yaw rate are above the corresponding base threshold for a first predetermined duration; (d) in the impact-presumed state (36), monitoring a plurality of dynamic vehicle behaviors to confirm the occurrence of the minor impact (37), wherein the method returns to the baseline state (33) if the acceleration and yaw rate do not remain above the corresponding baseline threshold or if the determined distance does not remain less than the distance to the edge of the vehicle; and (e) detecting the slight impact (37) if at least one of the behaviors confirms the occurrence.

Description

GENERAL STATE OF THE ART

[0001] The present invention relates generally to motor vehicle collision detection and, more particularly, to detecting the occurrence of a mild to moderate impact event whose severity is less than that of an impact that should trigger deployment of a passive restraint device, such as an airbag.

[0002] In particular, the present invention relates to a method for detecting a slight impact against a vehicle and to a vehicle device designed to carry out the method according to the independent patent claims.

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

[0004] A typical crash 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 responses, 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 agencies for accident reconstruction.

[0006] Known methods for sensing impacts in restraint systems may not be suitable for detecting light impacts because they typically require multiple sensors that may not be suitable for detecting light crashes, and they may require significant computing resources and / or data transmission. A typical automotive electronics architecture includes a plurality of distributed control modules and sensor devices connected as nodes in a multiplexed communications network. Given the ultimate uses for which light impact detection would be employed, an optimal implementation would typically locate the light impact detection function in a control module other than a restraint control module (e.g., a body control module or a powertrain control module), where computing resources may be scarce.

[0007] DE 10 2005 042 842 A1 describes the detection of impact events using acceleration sensor signals to activate pedestrian protection devices.

[0008] DE 10 2006 002 746 A1 describes a method for controlling personal protection devices in a motor vehicle - ie, in the terminology of the present invention, for detecting severe impact events - wherein the control is carried out on the basis of environmental signals and acceleration and speed signals.

[0009] In the impact detection system according to DE 10 2007 059 553 A1, forces acting via the wheels of the motor vehicle are additionally used for impact detection or the activation of occupant protection systems.

[0010] The object of the present invention is to achieve reliable detection of light impact events using low computational effort while consuming a minimal amount of data traffic over a multiplex control network.

[0011] The above-mentioned object is achieved by a method or a vehicle device having the features of the independent patent claims.

[0012] Advantageous embodiments of the invention are explained in the dependent patent claims. SUMMARY OF THE INVENTION

[0013] The light impact detection algorithm utilizes the vehicle's longitudinal and lateral acceleration, yaw rate, and vehicle speed, typically shared between different modules via a high-speed CAN bus. A body control module (BCM) provides a preferred location for implementing light impact detection. Sensor signals from accelerometers of the type installed as part of a vehicle dynamics system (e.g., a powertrain control, traction control, or braking system) typically have a range of approximately -10 g to approximately +10 g, which is sufficient to detect light impacts. Vehicle speed can be derived from wheel speed or from a transmission-based vehicle speed.A consolidated vehicle speed based on the combination of vehicle speed estimates from various vehicle systems may be desirable. Vehicle yaw rate (also available via a CAN bus from various motion sensors) is monitored to detect any unusual or undesirable angular velocity and acceleration that would be associated with minor impact conditions. Motion sensor information on roll rate can also be monitored / recorded to report the dynamic state in the event of a vehicle rollover. A driver's control intent, such as throttle position, driver brake pedal travel, driver steering angle, etc., can also be recorded from the high-speed CAN bus to obtain information on driver behavior before, during, and after a minor impact.

[0014] In one aspect of the invention, a method for detecting a minor impact against a vehicle is provided. A measured acceleration and a measured yaw rate are compared to corresponding baseline thresholds in a baseline state. If the acceleration is above the corresponding baseline threshold, 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 acceleration of the vehicle, and the measured yaw rate of the vehicle. If the determined distance is less than a distance to a vehicle edge, the transition to a presumed-impact state occurs if at least one of the acceleration and the yaw rate is above the corresponding baseline threshold for a first predetermined duration.In the presumed impact state, a variety of dynamic vehicle behaviors are monitored to confirm the occurrence of the minor impact. The procedure returns to the baseline state if the acceleration and yaw rate do not remain above the corresponding baseline threshold or if the calculated distance does not remain less than the distance to the edge of the vehicle. A minor impact is detected if at least one of the behaviors confirms the occurrence. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram of a vehicle with a light impact detection and recording system. Fig. Figure 2 shows a spectrum of impact severity from mild impacts to high severity impacts that result in the deployment of passive restraint devices. Fig. Figure 3 depicts graduated detection levels that employ progressively increasing levels of computing and data transmission resources as conditions increasingly indicate the possibility that a light impact is occurring. Fig. Figure 4 is a state diagram showing a preferred process of the invention. Fig. Figure 5 is a diagram showing a vehicle center of gravity, an impact point, and an impact distance. The Fig. 6A-6E are graphs showing example vehicle dynamics measurements, calculations, and detection flags used in an embodiment of the invention. Fig. Figure 7 is a flowchart showing a preferred method of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0015] With reference to Fig. 1, a vehicle 10 (such as a gasoline, electric, or hybrid motor vehicle 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.

[0016] A body control module (BCM) 15, coupled to bus 12, is typically present in a vehicle electrical architecture for performing general vehicle functions. The BCM 15 provides 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, which is 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 brake system (ABS) module 18 connected to associated sensors, such as wheel speed sensors.

[0017] 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 agencies 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).

[0018] The purpose of the light 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. Fig. Figure 2 shows the difference between the impact severity to be detected by the light impact detection function versus the airbag deployment function. The impact severity is proportional to a calculated change in velocity ΔV during an event. A "deployment impact" region 26 is located at a high ΔV above an RCM threshold. A "no impact" region 25 is located at a low ΔV. A "light impact" region 26 is located between regions 25 and 27.

[0019] To meet the competing goals of fast, accurate detection and minimal use of computational / multiplexing resources, the invention uses a multi-stage detection strategy as described in Fig. 3. In stage 1, shown in block 30, a number of sensitive initial or baseline conditions are monitored which provide a rough indication that an impact may occur. In particular, the vehicle acceleration and / or yaw rate may be used to provide such a rough indication. They may be compared to the appropriate thresholds such that the more computationally intensive operations for accurately detecting a mild impact are not performed if the acceleration and yaw rate are so low that an impact is clearly not occurring. Stage 1 preferably also includes a validity check based on a calculated impact distance between the vehicle's center of gravity and an estimated impact line, as further described below.

[0020] The transition to Level 2, shown in block 31, occurs when the acceleration or yaw rate monitored in Level 1 exceeds the appropriate thresholds (and the validity check does not rule out an impact event). Level 2 provides a delayed response by ensuring that the acceleration / yaw rate remains above the threshold for a predetermined duration (e.g., three consecutive values) before concluding that an impact is suspected. This helps prevent transient errors in the measured acceleration or yaw rate from triggering the full monitoring state entered in Level 3, shown in block 32. After the transition to Level 3 has occurred, more computationally intensive monitoring is performed in an attempt to confirm whether a minor impact has occurred.

[0021] Fig. Figure 4 shows a state diagram according to a preferred embodiment of the invention. A base state 33 performs the output monitoring, wherein the vehicle acceleration and / or yaw rates are compared with corresponding predetermined thresholds. In particular, a total vehicle acceleration a can preferably be calculated based on a square root of the sum of the squares of the measured longitudinal acceleration a x and a measured lateral acceleration a yThe measured accelerations can be obtained from the body control module via the CAN bus, for example, from a powertrain control module. The acceleration thresholds AccelerationCalibration1 and AccelerationCalibration2, and the yaw rate threshold Yaw RateCalibration1 can be used as conditions to trigger the Level 1 impact detection logic. More formally, an "in impact" condition can be detected in a control module according to the following pseudocode: where z is a time index, where the times z 1 , e.g. 2 and z 3 are consecutive values ​​collected in a time step interval ΔT, and where z 2 is the current value and z 1 is the previous value, g is the gravity constant, and InImpact is a flag used to capture a duration for which the condition remains true.

[0022] In state 34, a validity check is performed based on an impact distance. This means that if the impact distance is not within the vehicle's boundary edges, the vehicle dynamics would correspond to an impact occurring outside the vehicle's perimeter, which is not possible. Thus, the validity check helps prevent any false impact detection. The validity check can be performed either before or after the aforementioned test to determine the setting of the InImpact flag. If it is performed after the InImpact flag has been set and the validity check finds an invalid result, the InImpact flag is reset to 0 for the current detection period z.If it is executed before the InImpact comparison, an additional test would have to be inserted before the validation check to ensure that acceleration a is above a threshold, AccelerationCalibration1, to avoid undefined values ​​as described below. Thus, it may be preferable to execute the validation check after setting the InImpact flag, as in . Fig. shown.

[0023] The concepts for checking the impact distance are in Fig. illustrated. The vehicle 10 has a center of gravity (CG) 40, which is typically located slightly forward of the center of the vehicle 10. An impacting object 41 impacts the vehicle 10 at an impact point 42 as it travels along an impact line 43. An impact distance 44 is the shortest distance from the CG 40 to the line 43, and is CG The distance d CGis necessarily smaller than the longest distance from the CG 40 to a vehicle edge, which can be approximated as half of a diagonal length L of the vehicle. Fig. 5 also shows the longitudinal acceleration a x , the lateral acceleration a y , and the yaw rate ω, which are defined with respect to the CG 40, and a vehicle forward speed V x .

[0024] 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 40. The impact distance is only calculated if the total acceleration exceeds a predetermined threshold, so the above calculation does not involve dividing by zero.

[0025] To reduce noise in the calculation (due to inherent noise in the CAN bus-based acceleration and yaw rate signals) and for a more accurate impact distance estimate, a recursive least squares algorithm (RLS algorithm) is preferred for calculating the impact distance from the CG. Thus, the validity check can be performed as follows: where the result -1 is used to indicate that there is no impact (since no impact distance can be calculated). When the real-time RLS algorithm outputs a calculated value, it is compared with the vehicle edge distance (e.g., L / 2) and if d CG is greater than L / 2, then InImpact[z 2 ] is set to zero.

[0026] In condition 35 in Fig. 4, a delayed confirmation of the InImpact flag is used to determine the value of an Impact_Suspected flag. If the last three consecutive InImpact flags are 1, the Impact_Suspected flag changes from 0 to 1. In the following pseudocode, for example, 1 , e.g. 2 and z 3 the last three values ​​and the consecutive impact flags are InImpact[z 1 ], InImpact[z 2 ] and InImpact[z 3 ]:

[0027] If Impact_Suspected[z 3 ] is equal to 1, the procedure goes to state 36, otherwise it returns to the initial state 33.

[0028] In state 36, the Impact_Suspected flag is used to trigger tests of various dynamic behaviors that are more computationally intensive but can confirm the occurrence of a minor impact. The dynamic behaviors may include, for example, checking for threshold front and rear tire skidding, changes in longitudinal and lateral velocity, sustained excessive acceleration or yaw rate, and lane departure rate. Each of these behaviors is described in more detail below. If any of the behaviors are detected, a transition occurs to an Impact Confirmed state 37.In state 37, details of the occurrence may be stored, transmitted off-vehicle for reporting purposes, transmitted wirelessly to warn nearby vehicles, or used to modify the operation of the host vehicle, such as by changing the powertrain characteristics or changing the operation of the passive restraint system, as the likelihood of a major secondary impact may be increased.

[0029] A first dynamic behavior is a "shortest plausible time," where the Impact_Suspected flag is integrated over time, denoted by TimeInImpact. An impact is confirmed when the Impact_Suspected flag is enabled and the TimeInImpact exceeds a predefined threshold ImpactDurationCalibration1. For example, with an acquisition interval of ΔT, an integration threshold of ImpactDurationCalibration1 (> ΔT) was used.

[0030] Another dynamic behavior is a change in the longitudinal velocity. This is calculated by integrating the longitudinal velocity a x calculated as follows: Longitudinal change = ∫0taxdt

[0031] If an impact is suspected, LongitudinalGChange is compared to a threshold value of VelocityChangeCalibration1. If the condition abs(LongitudinalGChange) > VelocityChangeCalibration1 is met, the Impact_Confirmed flag changes from 0 to 1.

[0032] Another dynamic behavior is a change in the lateral velocity. This is calculated by integrating the lateral velocity a y calculated: Cross-change=∫0taydt

[0033] If an impact is suspected, the lateral change is compared to a threshold value of speed change calibration 2. If the condition abs(lateral change) > speed change calibration 2 is met, the impact_confirmed flag changes from 0 to 1.

[0034] The next dynamic behavior is the rate of sideslip due to yaw and lateral acceleration. This flag checks whether the front or rear tires exceed a predefined sideslip threshold. Sideslip calculations are performed using the following physically based model. First, the lateral acceleration a quer based on the measured sensor data a y , (ω z and v x calculated so that aquer=ay−ωz×vx.

[0035] Then the lateral velocity is vquer=∫0taquerdt.

[0036] The lateral velocity due to the yaw rate, ω z , is vWinkelFT=ω×dFT for front tires, and vAngleRT=ω×dRT for rear tire.

[0037] The total lateral speeds of the front and rear tires are vquerFT=vquer+vWinkelFT for front tires, and vquerRT=vquer−vWinkelRT for rear tires.

[0038] Thus, the side slip ratios for the front tire and the rear tire are SideslipFT=vquerFT / vx for front tires, and SideslipRT=vquerRT / vx for rear tires.

[0039] Then, the impact confirmation is obtained by using the predefined thresholds, SideslipCalibration1 and SideslipCalibration2, of the sideslip ratios for the front and rear axles.

[0040] For the front axle the corresponding pseudocode is and for the rear axle it is

[0041] Another dynamic behavior is a yaw rate threshold. This threshold is set for the yaw rate so that an unusually high angular velocity of the vehicle is detected as follows:

[0042] For example, the predetermined value for the YawRateCalibration2 threshold may be approximately 1 radian per second.

[0043] Another dynamic behavior for confirming a minor impact 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 value, AccelerationCalibration3, an impact is confirmed as follows:

[0044] Any of the vehicle dynamic behaviors described above is sufficient to conclude that a minor impact has occurred. Each behavior can be monitored using measured variables, typically available in a control network via a multiplexed bus in a vehicle. Other dynamic behaviors may also be used depending on the available sensor inputs.

[0045] The Fig. 6A-6F show exemplary waveforms for various signals during operation of the present invention. Fig. Figure 6A depicts the overall vehicle acceleration a, which increases from a value of zero to a higher value over a trajectory 50. In the example shown, the acceleration increases above the corresponding threshold, so a minor impact is suspected. Fig. Figure 6B shows the yaw rate, which initially doesn't change much. A yaw rate that is inconsistent with the vehicle's current heading and the center of gravity would be more indicative of an impact. Fig. Figure 6C shows the InImpact flag transitioning from a logic level of 0 to a logic level of 1 at segment 51, which coincides with the time at which the acceleration in Fig. 6A rises above the corresponding threshold. In Fig. 6A, the acceleration remains high for a certain period of time until the measured acceleration decreases along a trajectory 53. As a result, the flag InImpact at 54 goes into Fig. 6C back to 0. In Fig. 6A, the acceleration then increases again along a trajectory 56, which causes the flag InImpact in Fig. 6C at 57 goes back to a value of 1.

[0046] Fig. Figure 6D shows the Impact_Suspected flag transitioning from 0 to 1 at transition 52, which coincides with the InImpact flag remaining at the high logic level for the predetermined duration, such as three consecutive detection periods. The Impact_Suspected flag returns to the low logic level at 55 concurrently with the negative transition of the InImpact flag at 54. Fig. 6C to a value of 0. After the InImpact flag has remained at a high logic level 1 for the predetermined period of time following the transition at 57, the Impact_Suspected flag also returns to a high logic level value 1 at transition 58 in Fig. 6D back.

[0047] Fig. Figure 6E depicts a vehicle dynamic behavior for confirming a minor impact, with the flag Impact_Suspected integrated. Thus, if the signal in Fig. 6D has a high logic level, the integration value increases in Fig. 6E as shown at segment 59. An Impact Confirmed flag can be set if the integrated value in Fig. 6E exceeds the corresponding threshold. This behavior corresponds to confirming the minor impact if at least one of the acceleration or the yaw rate remains above the corresponding base threshold for a second predetermined duration greater than the first predetermined duration.

[0048] In Fig.Figure 7 shows a method according to the invention, wherein the acceleration and yaw rate are measured in step 70. In step 71, a check is made to determine whether the overall vehicle acceleration or yaw rate exceeds the corresponding base thresholds. If not, a return is made to step 70 to obtain additional measurements. If a threshold is exceeded, a check is made in step 72 to determine whether the impact distance is less than the vehicle edge distance. If it is not, the excessive acceleration or yaw rate does not indicate a valid impact, and a return is made to step 70. If the impact distance is less than the vehicle edge distance (and not equal to -1, when used to indicate that the impact distance cannot be determined), the InImpact flag is set in step 73.At step 74, a check is then performed to determine whether the three most recent values ​​all resulted in the InImpact flag being set to 1. If not, the program returns to step 70 for further measurements.

[0049] If the InCrash flag was set in step 74 for three consecutive detection periods, the Impact_Suspected flag is set in step 75. Then, in step 76, the dynamic vehicle behaviors are examined to determine if any of them confirm an impact. If not, a check is performed in step 77 to determine if the possible presence of an impact is still suspected, and if so, a return is made to step 76 to continue monitoring the dynamic behaviors. Otherwise, a return is made to step 70. If any dynamic behavior confirms an impact, the Impact_Confirmed flag is set in step 78. Then, details of the minor impact can be stored or reported, or used to change the vehicle operating parameters in step 79.

Claims

A method for detecting a minor impact against a vehicle (10), comprising: (a) comparing a measured acceleration and a measured yaw rate with corresponding baseline thresholds in a baseline state (33); (b) if the acceleration is above the corresponding baseline threshold, determining (34) 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 acceleration of the vehicle (10), and the measured yaw rate of the vehicle (10); (c) if the determined distance is less than a distance to a vehicle edge, transitioning to a presumed impact state (36) if at least one of the acceleration and the yaw rate is above the corresponding baseline threshold for a first predetermined duration;(d) in the impact-suspected state (36), monitoring a plurality of dynamic vehicle behaviors to confirm the occurrence of the minor impact (37), wherein the method returns to the baseline state (33) if the acceleration and yaw rate do not remain above the corresponding baseline threshold or if the determined distance does not remain less than the distance to the edge of the vehicle; and (e) detecting the minor impact (37) if at least one of the behaviors confirms the occurrence.; The method of claim 1, wherein the behaviors include:confirming the minor impact (37) when at least one of the acceleration and the yaw rate remains above the corresponding base threshold for a second predetermined duration greater than the first predetermined duration. The method of claim 1, wherein the behaviors include: determining a difference in vehicle speeds measured at two different times; and confirming the minor impact (37) if the difference is greater than a predetermined difference. Method according to claim 3, wherein the vehicle speeds are longitudinal speeds. Method according to claim 3, wherein the vehicle speeds are lateral speeds. The method of claim 1, wherein the behaviors include: determining a side slip ratio for each of a front axle and a rear axle of the vehicle (10); and confirming the minor impact (37) if at least one of the side slip ratios is greater than a predetermined side slip ratio. The method of claim 1, wherein the behaviors include:confirming the light impact (37) when the yaw rate exceeds a predetermined maximum angular velocity. The method of claim 1, wherein the behaviors include: determining a lane departure acceleration in response to the yaw rate and a longitudinal velocity of the vehicle (10); and confirming the minor impact (37) when the lane departure acceleration exceeds a lane departure threshold. The method of claim 1, wherein the center of gravity to impact distance is further determined according to a recursive least squares fit. The method of claim 1, wherein the measured acceleration consists of a total acceleration derived from the measured longitudinal acceleration and the measured lateral acceleration. A vehicle device comprising: vehicle dynamics sensors that measure vehicle acceleration and yaw motion; a control network (11) having at least one control module communicatively coupled to the dynamics sensors, the control network: (a) comparing a measured acceleration and a measured yaw rate to corresponding baseline thresholds in a baseline state (33); (b) if the acceleration is above the corresponding baseline threshold, 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 acceleration of the vehicle (10), and the measured yaw rate of the vehicle (10); (c) if the determined distance is less than a distance to a vehicle edge, transitioning to a presumed-impact state (36) when at least one of the acceleration and the yaw rate are above the corresponding baseline threshold for a first predetermined duration;(d) in the presumed-impact state (36), monitor a plurality of dynamic vehicle behaviors to confirm the occurrence of the light impact, wherein the control network returns to the baseline state if the measured acceleration and yaw rate do not remain above the corresponding baseline threshold or if the determined distance does not remain less than the distance to the edge of the vehicle; and (e) detect the light impact (37) if at least one of the behaviors confirms the occurrence.; The vehicle device of claim 11, further comprising a non-volatile memory (20) for recording data associated with the confirmed minor impact, including a time, a date, and a position. The vehicle device of claim 11, further including a passive restraint system that is deployed in response to impacts having a severity greater than a minor impact severity, the passive restraint system performing an impact sensing function that is adjusted in response to confirmation of a minor impact. The vehicle device of claim 11, wherein the behaviors include:confirming the minor impact (37) when at least one of the acceleration and the yaw rate remains above the corresponding base threshold for a second predetermined duration greater than the first predetermined duration. The vehicle device of claim 11, wherein the behaviors include: determining a difference in vehicle speeds measured at two different times; and confirming the minor impact (37) if the difference is greater than a predetermined difference. The vehicle device of claim 11, wherein the behaviors include: determining a side slip ratio for each of a front axle and a rear axle of the vehicle (10); and confirming the minor impact (37) when at least one of the side slip ratios is greater than a predetermined side slip ratio. The vehicle device of claim 11, wherein the behaviors include:confirming the light impact (37) when the yaw rate exceeds a predetermined maximum angular velocity. The vehicle device of claim 11, wherein the behaviors include: determining a lane departure acceleration in response to the yaw rate and a longitudinal velocity of the vehicle (10); and confirming the minor impact (37) when the lane departure acceleration exceeds a lane departure threshold. A vehicle device according to claim 11, wherein the distance from the center of gravity to the impact is calculated according to a recursive least squares fit. Vehicle device according to claim 11, wherein the measured acceleration consists of a total acceleration derived from the measured longitudinal acceleration and the measured lateral acceleration.

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