Patent Publication Number: US-2005116829-A1

Title: Method for ascertaining a critical driving behavior

Description:
BACKGROUND INFORMATION  
      The present invention relates to a method for ascertaining a critical driving behavior. A method for warning a driver of a vehicle is described in German Patent Application No. DE 100 39 795 A1. In that case, the output of warnings is controlled as a function of the driver&#39;s attentiveness. This prevents warnings of critical situations from being output to a driver when he/she has already perceived a danger. It is also proposed to ascertain the attentiveness of the driver as low when a predefined value of an operative-control frequency of a device is exceeded.  
     SUMMARY  
      A method according to an example embodiment of the present invention may have the advantage that not only a comparison to a predefined value is carried out for ascertaining a critical driving behavior, but also a comparison to a user profile of a driver. To be understood by operative-control behavior of the driver is the frequency of individual operative-control actions, their dynamics and their effect, i.e., the changes resulting from the adjustments in the vehicle. In particular, operative controls of vehicle components are evaluated for which a change has a direct effect on the driver himself, e.g., an air-conditioning function, a seat adjustment or a selection on the radio. For example, a desired, excessively high temperature in the vehicle, or also the opening of a window when the inside temperature is relatively pleasant may be conspicuous. By comparing the operative-control behavior to, for example, a driver-specific user profile, it is possible to determine a critical driving behavior of a user more precisely than merely by a comparison to a predefined value. In addition, the user profile may include a plurality of characteristic quantities, so that it becomes possible to not merely already ascertain a critical driving behavior in response to the deviation of a single characteristic quantity, but rather to consider various deviations in combined fashion for determining a critical driving behavior. The accuracy with which a critical driving behavior can be determined is also thereby increased. On one hand, it is therefore ensured that a driver is warned of actually critical driving situations when he/she exhibits a critical driving behavior. On the other hand, unnecessary warnings are avoided, so that the acceptance of the system by a user is increased.  
      According to an embodiment of the present invention, it may be particularly advantageous to evaluate an operative-control frequency, an operative-control selection and/or operative-control dynamics of an operative control by a user for determining a critical driving behavior, and to compare them to a stored user profile. The reason is that an increased operative-control frequency of vehicle systems or vehicle functions, particularly comfort functions such as the seat adjustment, the air-conditioning control or opening of the window or sunroof indicates that a driver feels ill at ease in the vehicle and is attempting to produce the most comfortable possible situation again in the vehicle.  
      An unusual operative-control selection, such as the window open, the air conditioner especially cold and/or the car radio particularly loud, which deviates from the usual settings by a driver can give an indication that the driver is becoming tired, for example, and wants to combat his/her fatigue using these adjustments. The driving behavior is possibly to be evaluated as critical in this case, as well.  
      Increased operative-control dynamics, to be understood by operative-control dynamics being a measure for the force with which a manually actuatable operating element is actuated, may infer increased aggressiveness of the driver. A particularly aggressive driver may not be inclined to observe safety distances or speed limits. The driving behavior is to be evaluated as critical in this case, as well.  
      If a critical driving behavior has been determined, this can be relayed to various vehicle systems. The relay to warning systems, which can accordingly lower the warning thresholds at which driver warnings are output, is particularly advantageous.  
      In the event of a repeated deviation from a stored driver behavior, it is also advantageous to correct the user profile so that a precise determination of a critical driving behavior is retained and warnings are not output unnecessarily.  
      It is further advantageous that a motor vehicle is already equipped with a plurality of operator&#39;s controls. Information resulting from the selection of the settings or from a frequency of the setting changes or the operative-control dynamics may be ascertained without further costly components having to be installed in the vehicle for that purpose. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Exemplary embodiments of the present invention are shown in the figures and are explained in detail below.  
       FIG. 1  shows an example device of the present invention for carrying out the method of the present invention for ascertaining a critical driving behavior;  
       FIG. 2  shows an example method sequence of the present invention for ascertaining a critical driving behavior. 
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS  
      The method of the present invention may be used in any vehicles. The use in motor vehicles is particularly advantageous, since they are possibly used by several users, so that in each case a personal assignment of a user profile to one driver permits optimal adaptation of the detection of a critical driving behavior to the specific driver. In addition, in contrast to, for example, airplanes or rail vehicles, motor vehicles are not subject to central monitoring, so that critical driving behavior will possibly remain undiscovered, thereby increasing the risk for the driver and other road users. In the following, the method of the present invention is explained using a practical application in a motor vehicle as an example.  
       FIG. 1  shows a central data acquisition unit  1  used for determining the driver behavior. Data acquisition unit  1  is connected to the controls of various vehicle systems. An operative control of a vehicle system or a selection of a vehicle function is communicated to data acquisition unit  1 . A car radio  2 , inter alia, is connected to data acquisition unit  1  for this purpose. Car radio  2  has push buttons and/or rotary controls  3  used for selecting a radio program and controlling the volume of car radio  2 . A seat-adjustment unit  4  is also connected to data acquisition unit  1 , a seat adjustment being implemented via a rocker switch  5 . Moreover, an air-conditioning control  6 , a window adjuster  7 , a sunroof control  8  and a foot-pedals detector  9  are connected to data acquisition unit  1 . The accelerator pedal, the clutch pedal and/or the brake pedal is/are included in foot-pedals detector  9 . Fewer, but also even further operating units in the vehicle may be connected to data acquisition unit  1 .  
      At least one of the following variables is acquired from the operating units: frequency of an actuation of an operating element per unit of time, type of function selected, force used during the actuation. Instead of a discrete connection for each of the vehicle components or vehicle operative-control components, they may also be connected to data acquisition unit  1  via a bus system.  
      Data acquisition unit  1  has a processing unit  10  which processes the input data. Processing unit  10  compares the data concerning the operative control of the operating units, and therefore the operative-control behavior of the driver, to a user profile stored in a memory  11 . The user profile is stored in non-volatile manner in memory  11 . It may be supplied to memory  11  via a data interface. Thus, for example, it is possible to provide an insertion opening  12  for a data medium card  13 , e.g., a card having an applied memory chip, on data acquisition unit  1  or at another suitable location in the vehicle with data contact to data acquisition unit  1 .  
      Data acquisition unit  1  may be implemented as a hardware component which optionally even has its own housing. However, it is also possible to implement data acquisition unit  1  as a software component which has suitable software interfaces to the indicated remaining systems.  
      The individual vehicle functions concerning which the user profile has information are stored in memory  11  in a first column  14 . Stored values with respect to the plurality of user functions are in further lines  15 ,  15 ′. A value for the frequency with which a vehicle function is operated is stored in a second column  28 . Preferred selection and parameters for the vehicle function are stored in a third column  16 . A typical force for the operative control of an allocated operating element is stored in a fourth column  17 . If processing unit  10  determines deviations between the measured values of the vehicle operative control and the user profile stored in memory  11 , this deviation is stored in a deviation memory  18 . If the deviation occurs more frequently, the user profile is corrected accordingly in the deviating entry in the direction of the deviation. Deviation memory  18  is preferably also implemented as a nonvolatile memory, so that the deviations are available even after the vehicle is switched off. The deviations are only erased when either a certain period of time has elapsed since their entry, or the value stored in memory  11  was corrected in the appropriate direction which the deviation specifies. In one preferred embodiment, it is possible to create a separate user profile of the operative-control behavior for each driver, which is selected after a suitable identification of a user and is processed by processing unit  10 .  
      In one special specific embodiment, it is possible that only deviations from standard values predefined in a further memory unit (not shown) have to be stored in the user profile of the operative-control behavior. This makes it possible to save on memory space. A reduction in memory space is possible in particular for the case when a driver does not use various functions. Given storage on a memory card, which can also be transferred to other vehicles having a device according to the present invention, a vehicle-specific adaptation may therefore be implemented. Thus, when driving, a higher volume adjustment of a radio can be assumed in a vehicle with greater wind noise than in a vehicle in whose passenger compartment it is generally quiet.  
      Therefore, when the user profile is transferred to another vehicle, it may be adapted immediately to the other vehicle.  
      The force during an operative control, e.g., during an activation of the vehicle horn or when operating the radio, is advantageously measured by operator&#39;s controls which have sensor systems sensitive either to acceleration or to force. For example, one design is possible using resistive sensors or sensors based on piezo technology for registering acting forces. The sensors are situated on the operator&#39;s controls or inserted into them and ascertain the force acting on the operator&#39;s control during an actuation by a user. The information about the force exerted during the operative control is passed on to data acquisition unit  1 .  
      A processing procedure according to the present invention for determining a critical driver behavior is shown in  FIG. 2 . Starting from an initialization step  20 , the driver behavior begins to be monitored. In one preferred embodiment, monitoring of the driver behavior begins only approximately five minutes after the vehicle has been started, i.e., only when the coolant has reached operating temperature. This prevents adaptations of the vehicle functions at the beginning of a trip to the current driving situation from invalidating an assessment of the driver behavior. For example, in winter, an extreme direction of the ventilation toward a windshield at maximum heating output is selected for defrosting the windshield. However, no conclusion concerning the driver behavior can be inferred from such an adjustment. The same holds true, for instance, for a vehicle which was switched off in the sun and which initially should be cooled down by a suitable setting of the air conditioning.  
      Following initialization step  20  is a first data acquisition step  21 . In first data acquisition step  21 , a query as to the number of operative controls carried out since the last acquisition is conducted at those vehicle components which provide this data. In a second subsequent data acquisition step  22 , in the same way an operative-control selection is queried, i.e., which function was selected in this period of time. In a subsequent third data acquisition step  23 , there is a query as to how great the operative-control force was for a specific individual operative control carried out since the last query. The variables—operative-control frequency, setting inputs and operative-control dynamics—thus obtained are each compared to the values stored in columns  28 ,  16 ,  17 . To this end, it may also be necessary to determine the operative-control frequency from the number of operative controls in relation to the data acquisition time.  
      For a car radio, for example, as operative-control frequency, an operative control of one user interaction per minute may be predefined as a limiting value. A specific volume-level range and/or a specific radio tuning may be predefined as the function selection. The force of 100 newtons may be predefined, for example, as a limiting value for a force on an operating element. For a climate-control device, for example, one actuation in three minutes, a temperature selection of 22° and an operative-control force of 80 newtons may be provided. These values are either set by a user or are initially predefined at the factory, but are adapted to the desires of a user during utilization.  
      Furthermore, a typical value may be predefined for a cruise control within the framework of a distance-control device, for instance; in this case, no operative-control pressure and no operative-control frequency are acquired at the same time. It is also possible, for example, upon actuation of the sunroof, to record merely the operative-control frequency, while when a power-window unit is actuated, both the operative-control frequency and the operative-control selection, e.g., half open or completely open window, are also recorded. With respect to the foot pedals, both the operative-control frequency and the operative-control dynamics are advantageously recorded. In this context, the accelerator and the brake are monitored in particular.  
      In a first check step  24  following third data acquisition step  23 , the deviations—i.e., the exceeding of limit values of the ascertained user data—from the stored user profile are determined. Preferably, a single deviation in a stored operative-control behavior is not yet sufficient for the data acquisition unit to determine a critical driving behavior. At least three different deviations in one data acquisition period are preferably necessary for this purpose. Optionally, certain correlation instructions, where a certain combination of deviations must be fulfilled, may be predefined for data acquisition unit  1 . For example, an open window together at the same time with a loudly adjusted radio will lead to the determination of a critical driving behavior, namely, to the determination that a driver is tired. If no such deviation is established in first check step  24 , then the data acquisition steps are repeated after a predefined period of time, e.g., after one minute. If, however, it is established in first check step  24  that a sufficient number of deviations exist, then the procedure branches to a second check step  25 . In second check step  25 , it is checked whether this deviation has already occurred in the past. To this end, the ascertained deviations are compared to the deviations stored in deviation memory  18 . If the deviation has already occurred several times, e.g. already during a previous trip or for a longer period of time, e.g. an hour, then the procedure branches to a correction step  26  in which the stored user profile is corrected by an average using the recorded deviations. However, if it is detected in second check step  25  that until now, such deviations have occurred only seldom or not at all, then the procedure branches to an output step  27  in which the deviation is written into deviation memory  18 . In addition, data acquisition unit  1  outputs a corresponding information signal to a data bus  19 , to which in turn a plurality of vehicle components is connected. In a first specific embodiment, the data acquisition unit only outputs that a critical driving behavior exists. In a further specific embodiment, however, suitable evaluation data may also be made available to processing unit  10 , based on which processing unit  10  is able to ascertain which critical driving behavior is possibly involved. For instance, given frequent actuation of the foot pedals, this could be aggressive driving. Given frequent operative control of the radio together with an open window or a climate control system set to be particularly cold, it could, for example, be driver fatigue.  
      In the exemplary embodiment shown here, a unit  30  for travel following a preceding vehicle at a regulated distance, a device  31  warning that the vehicle is leaving its lane, a parking device  32  and a display instrument  33  for receiving the indications of a critical driving behavior are connected to data bus  19 . The device for following a preceding vehicle at a regulated distance selects a larger distance value which is maintained to a preceding vehicle when a critical driver behavior is ascertained. Device  31  for warning that the vehicle is leaving its lane already outputs warnings earlier, thus already upon approaching lateral roadway boundaries or in response to a slight exceeding of the lateral roadway boundaries. Parking device  32  already outputs warnings at greater distance values to obstacles. In one preferred specific embodiment, a corresponding warning field which indicates a critical warning behavior to the driver, e.g., by the representation of a warning triangle, is lighted from behind in display instrument  33 . With a suitable display, the driver also receives an indication that his/her driving behavior is possibly critical and he/she should possibly have a pause.