Abstract:
A dangerous driving conditions warning system for a vehicle such as an automobile is described. The warning system captures signals from two or more devices in an automobile, such as speedometer, distance measuring device, and airbag, and conveys the signals to a decision circuit which determines whether a dangerous driving condition exists and outputs an activation signal upon detecting a dangerous condition. The activation signal is sent to and activates an indicator such as a warning light or loud audible warning. The warning indicator alerts a trailing vehicle and other vehicles near the vehicle equipped with the warning system of the existence of one of various conditions warranting caution, a reduction in speed, or a veering or turn.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to automobile safety systems, and particularly to a computerized vehicle system and method for warning other drivers of dangerous driving conditions. 
     Automobiles and other vehicles contain an increasing number of safety devices such as airbags, anti-lock brakes, and traction-control systems to deal with dangerous road conditions and protect drivers of vehicles so equipped. These devices prove effective in many cases in preventing accidents or in protecting drivers during an accident. However, there is no substitute for safe and careful driving. 
     A big part of safe driving is awareness by the driver of problems which may be arising. This awareness must be obtained in time to act accordingly. However, the condition of the road or vehicle ahead of a given driver is often not apparent to the driver until it is too late to take appropriate action. If a dangerous condition exists, an automobile driving ahead is likely to encounter the problem before automobiles behind them. By the time the trailing automobiles become aware of the problem, it is frequently too late to take effective action. 
     U.S. Pat. No. 5,786,752 issued Jul. 28, 1998 to Bucalo et al. discloses an emergency signal system for vehicles which alerts drivers approaching from the rear of a vehicle of a deceleration of the vehicle which exceeds a predetermined threshold. However, this system is similar to brake light systems and only alerts drivers of absolute speed changes of the vehicle so equipped. The system fails to alert other drivers of dangerous road conditions or of dangerous relative speed changes between the two vehicles. 
     There is thus a need for a system which warns drivers of dangerous road conditions in time to attempt safety measures. 
     SUMMARY OF THE INVENTION 
     The problems described above are solved by, in preferred embodiments, a dangerous driving conditions warning system for a vehicle such as an automobile. The warning system captures signals from two or more devices in an automobile and conveys the signals to a decision circuit which determines whether a dangerous driving condition exists and outputs an activation signal upon detecting a dangerous condition. The activation signal is sent to and activates an indicator such as a warning light or loud audible warning. The warning indicator alerts a trailing vehicle and other vehicles near the vehicle equipped with the warning system of the existence of one of various conditions warranting caution, a reduction in speed, or a veering or turn. 
     The warning indicator may be a light illuminated when a dangerous condition is detected. The light may be similar in construction to the tail lights of a car and mounted on the rear of the equipped vehicle such as near the third brake light. A second similar light may also be mounted on the front of the vehicle to alert other drivers of the difficulty with the equipped vehicle. The warning indicator may alternatively be an audible signaler such as the horn or an additional sound making device. 
     In preferred embodiments, the devices from which signals are received include an anti-lock braking system, a speedometer, an odometer, a distance sensor, a traction control system, an airbag deployment system, and a manual trigger. The conditions which can be detected include anti-lock activation, slippery road conditions, tailgating, rapid deceleration, airbag deployment, and excessive approach speed by the trailing automobile. 
     Some of the problems described above are also solved by a system for warning other drivers of a dangerous driving condition, in which the system includes a distance sensor for measuring distances between the first and second vehicles at a plurality of times, a decision circuit, coupled to receive signals from the distance sensor, for detecting a dangerous driving condition based on the distances measured by the distance sensor, and an indicator coupled to and selectively activated by the decision circuit for indicating the detection of the dangerous driving condition, the indicator being perceivable by the driver of the second vehicle. In particular embodiments, the distance sensor is installed on the rear of the vehicle equipped with the warning system, the decision circuit is capable of detecting excessive approach speed of a trailing vehicle, and the indicator is a warning light installed on the rear of the equipped vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a driving warning system in accordance with one preferred embodiment of the present invention. 
     FIG. 2 is a block diagram of a preferred embodiment of the decision circuit shown in FIG. 1 in accordance with the present invention. 
     FIG. 3 is a flow chart showing the process of monitoring safety devices and producing a warning in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the system and method of the present invention are now described with reference to FIGS. 1-3. Referring to FIG. 1, a warning system  10  in accordance with the invention includes wires  12  connected to a number of device sources 1, 2, . . . n, 14 in an automobile, a warning activation decision circuit  16  connected to and receiving signals carried over wires  12  from the sources  14 , and a light module  18  coupled to and activated by the decision circuit  16 . 
     The device sources include any of a variety of measuring devices and safety systems commonly found in or which may be installed on automobiles. The safety devices include airbags, anti-lock brakes, and traction control systems, and the measuring devices include speedometers, odometers, and radar, sonar, or laser based distance measuring devices which measure the distance between the equipped automobile and a stationary or mobile object or vehicle. The operations of and signals produced by all the devices are known to those skilled in the art, and are further described in the following patents, all of which are hereby incorporated by reference into this application as background information: 
     airbags—U.S. Pat. No. 5,787,377 to Watanabe et al.; U.S. Pat. No. 5,718,451 to White; U.S. Pat. No. 5,459,449 to Ravas, Jr. et al.; and U.S. Pat. No. 5,394,326 to Liu; 
     anti-lock brakes—U.S. Pat. No. 5,684,702 to Phillips et al.; U.S. Pat. No. 5,522,652 to Negrin et al.; U.S. Pat. No. 5,431,488 to DeVore; U.S. Pat. No. 5,001,641 to Makino; and U.S. Pat. No. 4,840,436 to Burgdorf; 
     traction-control—U.S. Pat. No. 5,593,217 to Schmitt et al.; U.S. Pat. No. 5,241,478 to Inoue et al.; U.S. Pat. No. 5,018,595 to Hara et al.; and U.S. Pat. No. 4,924,396 to Fulioka et al.; 
     speedometers and odometers—U.S. Pat. No. 5,659,290 to Haeri; U.S. Pat. No. 4,916,953 to Lie; U.S. Pat. No. 4,647,901 to Teshima et al.; U.S. Pat. No. 4,012,736 to Angwin; 
     distance measuring devices—U.S. Pat. No. 5,757,308 to Lissel et al.; U.S. Pat. No. 5,633,705 to Asayama; U.S. Pat. No. 5,510,990 to Hibino et al.; and U.S. Pat. No. 4,948,246 to Shigematsu. 
     As described in these patents, and as known to those of skill in the art, the nature of the signals vary among these various devices. Some of the devices have only two activation states—on and off—and thus produce a single bit signal. Airbags and anti-lock brakes produce such a single bit signal. Other devices, such as digital speedometers, odometers and distance measuring devices, produce multi-bit signals which are translated by the particular device into the desired information. Among these multi-bit devices, some may produce a signal which is in a special or proprietary format which is not generally compatible with standard digital signal processors, and others may produce signals which are compatible in format with conventional processors. Finally, some devices, such as older model speedometers and odometers, produce analog signals which would need to be converted to digital format for use by a digital signal processor. 
     The wires  12  which convey the signals from these devices to the decision circuit  16  may be electrical conductors having one end appropriately connected to capture the signal produced by each device. Other alternative signal conveyers may be used, including rf transmitters, optical fiber, etc. The wires or other signal conveyers carry signals from each of the devices  14  to the decision circuit  16  at sufficient strength to be usable by the decision circuit  16 , and may require amplification. 
     The light module  18  is a light which can assume at least two activation states—on and off—and is installed at a location clearly visible to other drivers. For example, the light module  18  may be a yellow “slow” light similar in construction to and mounted near the third brake light at the rear of the automobile. Two light modules may be provided on either side of the brake light, or light modules  18  may be installed above and below the brake light, completely around the brake light, and/or in other locations such as the rear windshield. As an alternative, the light module  18  may be replaced or supplemented by an audible signal loud enough for other drivers to hear. 
     The warning system  10  is programmed to warn drivers of other automobiles of a number of dangerous road and driving conditions, including slippery road, sudden drastic stops or swerves by the equipped automobile, tailgating by the automobile trailing the equipped automobile, and speeding or excessive approach speed by the trailing automobile. The decision circuit  16  determines whether any of these conditions exists based upon the signals received over the wires  12  and stored logic. 
     A particular embodiment of the decision circuit  16  is shown in FIG.  2 . As shown in FIG. 2, warning activation decision circuit  16  contains a digital processor  20  such as a microprocessor, microcontroller, or digital signal processor (DSP) such as the ME model DSP 16000 or other models available from Lucent Technologies, Inc., the assignee of the present application. The digital processor  20  is coupled to a program memory  22  such as ROM storing a program for operating the decision circuit  16  and a data memory  24  such as a RAM for temporarily storing data values for comparison with data values received at other times as explained below. 
     The decision circuit  16  further contains two multiplexers  26 ,  28  for each selecting one of a number of signals  12  of the same type for processing at any given time. One multiplexer  26  selects between a number of analog signals received from analog device sources  14   a  such as analog speedometers and odometers. The selected signal is passed along to an analog-to-digital converter  30  which converts the analog signal to a digital data value suitable for input into the digital processor  20 . Another multiplexer  28  selects among a number of pre-existing digital device sources having multi-bit outputs  14   b , such as a digital speedometer, and passes the selected signal to a data reformatter  32 . The data reformatter  32  reformats the digital signal from the selected pre-existing source  14   b  from the special format of that device to a standardized format suitable for input to the digital processor  20 . As one skilled in the art will recognize, the data reformatter may perform this reformatting in accordance with a predefined algorithm for the given device source or by consulting a translation table contained therein. 
     The digital processor  20 , multiplexers  26 ,  28 , A/D converter  30 , and data reformatter  32  are provided timing signals from a clock  34 . The multiplexers  26 ,  28  select among the multiple signal inputs  12  on a polling arrangement timed by the clock  34  or under the control of the digital processor  20  through feedback lines  36  in accordance with any desired control scheme. 
     The digital processor  20  receives a number of signals directly, including signals from digital sources with directly compatible multi-bit outputs  14   c , such as microprocessor-controlled devices, and a single bit signal from a manual trigger  14   d  which may be activated by the driver of the equipped automobile in case of emergency. The manual trigger may be used by the driver to toggle the state of the warning light  18  manually, either by activating the automobile horn or via a second switch dedicated to this purpose. In this mode, the light  18  cycles rapidly between states at a predetermined rate so that (a) if the light was already on (e.g., if the trailing driver is tailgating and the decision circuit  16  activates the light  18 ), then the driver can cause it to pulse on and off by engaging the manual trigger  14   d ; or (b) if the light is off, the driver of the equipped automobile can cause it to pulse to send a message to the trailing driver in a manual fashion, without needing to step on and off the brakes to pulse the brake lights. 
     The digital processor  20  processes the values in these data sources in accordance with procedures described below. The decision circuit  16  also contains a combinatorial logic element  36  which receives data output from the digital processor  20  as well as signals directly from single bit sources  14   e . The combinatorial logic element  36  receives the data from these various sources and decides in accordance with predefined logic whether to activate or deactivate the light  18 . The resulting output signal from the combinatorial logic  36  is amplified through an output amp  38  and transmitted to the light  18 . (FIG.  1 ). 
     As one skilled in the art will appreciate, the decision circuit  16 , and particularly the combinatorial logic element  36 , may be programmed or hard-wired to implement any number of possible procedures for determining whether a dangerous condition exists depending upon the data received from the source devices  14 . Table I below contains one such set of logic. 
     
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Dangerous Condition 
                 Logic 
               
               
                   
               
             
             
               
                 hard press on brakes by 
                 If anti-lock brake signal is active 
               
               
                 driver 
               
               
                 slippery road conditions 
                 If traction control system signal is active 
               
               
                 accident, collision, 
                 If airbag deployment signal is active 
               
               
                 sudden extremely short 
               
               
                 stop 
               
               
                 tailgating 
                 If distance to trailing car d divided by speed of 
               
               
                   
                 equipped car v is less than two seconds 
               
               
                 rapid deceleration 
                 If speed v 1  at first time t 1  minus speed v 2  at first 
               
               
                 of equipped car 
                 time t 2  divided by time difference t 2  - t 1  is 
               
               
                   
                 greater than a predetermined value (i.e., IF 
               
               
                   
                 (v 1  − v 2 )/(t 2  − t 1 ) &gt; k) 
               
               
                 excessive approach 
                 If the absolute value of the distance d 2  at time 
               
               
                 speed of trailing car 
                 t 2  minus the distance d 1  at an earlier time t 1   
               
               
                   
                 divided by time difference t 2  - t 1  is greater than 
               
               
                   
                 predetermined value and if distance d 2  at 
               
               
                   
                 time t 2 is less than a second predetermined value (i.e.,   
               
               
                   
                 IF | ((d 2  − d 1 )/(t 2  − t 1 )) | &gt; k 1  AND (d 2  &lt; k 2 )) 
               
               
                   
               
             
          
         
       
     
     Furthermore, FIG. 3 contains a flow chart showing one possible implementation of the logic of one particular embodiment of the invention. After receiving signals from the various sources, step  50 , converting the analog signals to digital format and reformatting certain digital signals, step  52 , the speed and distance values are stored temporarily, step  54 . If the anti-lock brake signal is active, step  56 , the traction control system signal is active, step  58 , or the airbag deployment signal is active, step  60 , the warning light is activated, step  100 . 
     If the current distance value divided by the current speed value is under two seconds or some other predetermined value, step  62 , this indicates a tailgating situation and the warning light is activated, step  100 . To check for rapid deceleration, a prior speed value from a given predefined time interval is retrieved, step  64 , and compared to the current speed to determine the rate of change of the speed, step  66 . If this speed differential is greater than a predetermined value, the warning light is activated  100 . To detect excessive approach speed, a prior distance value from a given predefined time interval is retrieved, step  68 , and compared to the current distance to determine the rate of change of the distance, step  70 . If this distance differential is greater than a predetermined value and the current distance value is less than another predetermined value, indicating the trailing car is too close and coming up too fast, the warning light is activated, step  100 . If none of the conditions exist, the warning light is or remains deactivated, step  102 . 
     If desired, the system  10  may be modified to provide more information to other drivers than the existence of a dangerous condition. For example, the other drivers can be informed of the nature of the detected dangerous condition by assigning a code to each condition and passing the code from the decision circuit  16  to the light module  18 . The light module  18  may contain various colored lights each representing a different condition or may contain a sign such as an LED display capable of displaying characters to identify the condition, such as “slippery road”, “tailgating”, or “approaching too fast”. The light module  18  selects the proper condition based upon the code and a stored table or data file of conditions and associated codes. Alternatively, the decision circuit  16  or light module  18  may contain a translation module for translating the detected condition to a predefined recommended action which is displayed to other drivers, such as “slow down”, “brake hard”, or “swerve”. 
     As a further alternative, the light module  18  may be capable of producing light at various intensity to indicate the severity of the dangerous condition. The decision circuit  16  may contain a number of stored parameters for comparison to the data values received from the various devices, each stored value representing another level of severity. For example, for detecting tailgating, the decision circuit  16  may compare the distance and speed values against several parameters, e.g., two seconds, one second, and one-half second, or may track a continuous time value for the tailgating, and sends severity data to the light module  18 . The light module then increases the intensity of the light emission as the severity of the tailgating increases. 
     While the invention has been described and illustrated in connection with preferred embodiments, many variations and modifications as will be evident to those skilled in this art may be made without departing from the spirit and scope of the invention. The invention is thus not to be limited to the precise details of methodology or construction set forth above as such variations and modification are intended to be included within the scope of the invention.