Abstract:
A method and a system using the Global Positioning System (GPS) to detect and report vehicle accidents are presented. GPS, which is currently used primarily for vehicle positioning, can be combined with wireless technology to automatically report accidents to third parties. A mobile unit placed or installed in a vehicle receives code sequences from the GPS satellites, converts the code sequences to positional information, and transmits the positional information to a server. The server derives the acceleration of the mobile unit from the positional information and compares the acceleration with a threshold value. In one embodiment, a microprocessor included in the mobile unit derives the acceleration and compares the acceleration with a threshold value. The threshold value represents acceleration that can be achieved only with an external force such as a collision. If the acceleration exceeds the threshold value, the server or the microprocessor automatically sends notification to third parties through the data network.

Description:
BACKGROUND 
     1. Field of Invention 
     The present invention relates a method and system for using the Global Positioning System and wireless communications technology to notify third parties of accidents. 
     2. Background of Invention 
     GPS is used to track vehicle positions. GPS includes a plurality of satellites orbiting the earth at a substantially constant speed and altitude. Each satellite transmits a code sequence that identifies the satellite and a GPS navigation message that is superimposed on the code sequence. Although the satellites are assigned frequencies at which they send their signals, Doppler effect prevents the signals from appearing exactly at the assigned frequencies. Thus, a GPS receiver often searches through a predefined range of frequencies to find the signal from the GPS satellites before tuning in to acquire the code sequence and the superimposed information. The superimposed information includes positional information (e.g., latitude, longitude, and altitude if necessary) and the time at which those positions were obtained. Further details on obtaining positional information from GPS satellites are provided in U.S. patent application Ser. No. 09/707326 to Fan et al. entitled “System and Method for Distribution of GPS Satellite Information,” and in U.S. Pat. No. 5,959,577 to Fan et al. entitled “Method and Structure for Distribution of Travel Information Using Network.” Both of the cited references are herein incorporated by reference. 
     Currently, the use of GPS is limited to tracking vehicle positions. Although vehicle safety is a concern for many people, GPS is not used as a tool for enhancing vehicle safety. Most reliable vehicle safety features today, such as seatbelts, air bags, and impact resistant bumpers, reduce the harm occupants might suffer as a result of a collision. However, the vehicle safety features available today do not focus on providing prompt notification of accidents to third parties. Once a collision occurs, prompt notification of third parties is desirable for accurate recording of the details of the collision and for calling for necessary medical care. The vehicle occupants may not be able to notify third parties due to a severe injury, and bystanders might not call for help. Therefore, a system that automatically and promptly notifies third parties of accidents is needed. 
     SUMMARY 
     The present invention provides a method and a system using the Global Positioning System (GPS) to detect and report vehicle accidents. A mobile unit that can be placed or installed in a vehicle receives code sequences from the GPS satellites and converts the code sequences to positional information. The mobile unit transmits the positional information to a server at regular time intervals using a data network. The server derives the acceleration of said mobile unit based on the positional information and compares the absolute value of the derived acceleration with a threshold value. 
     The threshold value represents the maximum rate of acceleration that can be achieved by normal driving actions, such as braking or speeding up. A derived acceleration value greater than the threshold value indicates that an external factor, such as a collision, is involved. Thus, upon detecting an acceleration value that exceeds the threshold value, the server automatically sends an accident notification to third parties through the data network. The notification may include, for example, the map of the area surrounding the accident site, air bag deployment status, seatbelt status, and the speed at which the vehicle was traveling at the time of the accident. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 illustrates a vehicle tracking system that utilizes GPS and a data network according to the present invention. 
     FIG. 2 illustrates a server included in the vehicle tracking system of the present invention. 
     FIG. 3 illustrates the logic flow of two different correction methods that can be used in the present invention. 
     FIG. 4 illustrates one embodiment of a vehicle tracking system in accordance with the present invention. 
     FIG. 5 represents one implementation of position table  34 . 
     FIG. 6 represents one implementation of threshold value table. 
     FIG. 7 illustrates one display of an accident notification in a monitor unit according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a vehicle locating system that utilizes GPS and a data network. The system shown in FIG. 1 includes GPS satellite constellation  2 , data network  4 , server  6 , monitor unit  8 , and mobile units  10 - 1  through  10 -n, n being the number of mobile units having the present invention. Each of mobile units  10 - 1  through  10 -n includes GPS receiver  12 - 1  through  12 -n, respectively, and network transmitter  14 - 1  through  14 -n, respectively. Optionally, mobile unit may also include a network receiver (not shown) through which it can receive information from data network  4 . As used herein, mobile unit  10 -i refers to one of mobile units  10 - 1  through  10 -n. Also, as used herein, GPS receiver  12 -i and network transmitter  14 -i each refer to the GPS receiver and the network transmitter that is included in the arbitrary mobile unit  10 -i. 
     Mobile unit  10 -i, which can be placed or installed in a vehicle, receives positional data from GPS satellites  2  and forwards the data to data network  4 . GPS receiver  12 -i of mobile unit  10 -i tunes into the satellite signal frequency and receives code sequences and the corresponding times from satellite constellation  2 . In some embodiments, mobile unit  10 -i converts the code sequences into pseudo-range information, either through GPS receiver  12 -i or through a separate microprocessor (not shown). Network transmitter  14 -i then sends the code sequences or the pseudo-range information and the corresponding time to link  5 . Link  5 , which forwards the information to data network, may include but is not limited to a satellite link, a wireless network service station such as a CDPD or CDMA station, a small message service, or a conventional data and voice switching network. Network transmitter  14 -i may automatically transmit information to data network  4  at a given time interval, or transmit information upon being triggered by a command entered through mobile unit  10 -i or monitor unit  8 . 
     Data network  4  may be, for example, the Internet or a telephone network. Once the information has been transmitted to data network  4 , server  6  and monitor unit  8  may retrieve the information from data network  4 . FIG. 2 shows the components of server  6 . As shown in FIG. 2, server  6  includes data processing unit  30 , area map storage  32 , position table  34 , and correction table  36 . Correction table  36  may contain correction factors or delta-pseudo-range data depending on the method server  6  uses to obtain the actual positions and velocities of mobile units  10 - 1  through  10 -n. The correction data and the delta-pseudo-range data, which are obtained from correction stations  37 , are correction factors for the geographical zone in which mobile unit  10 -i is located. Data processing unit  30  can connect to remote correction stations  37  via wired or wireless communication links, or via a data network  39  such as the Internet. Using the correction factors received from correction stations  37  and either the code sequences or the pseudo-ranges received from mobile unit  10 -i, data processing unit  30  of server  6  computes the actual positions and velocities of mobile units  10 - 1  through  10 -n. In one embodiment, GPS receiver  124  performs the conversion from pseudo-ranges to actual positions. In that embodiment, network transmitter  14 -i sends the actual positions to server  6  via data network  4 , and server  6  simply stores the actual positions in position table  34 . 
     FIG. 3 shows two methods by which code sequences can be converted to actual positions: correction factor method  40  and delta-pseudo-range method  42 . When using the correction factor method  40 , one of the correction stations  37  receive the code sequences from GPS satellites and obtains a measured position (latitude and longitude) of itself based on the received code sequences (step  44 ). The measured position, herein referred to as “fix,” is compared to the precisely known position of correction station  37  to obtain a positional correction factor for the longitude, herein referred to as delta-longitude, and a positional correction factor for the latitude, herein referred to as delta-latitude. Delta-longitude and delta-latitude, together referred to as delta-fixes, are stored in correction table  36 . The delta-fixes are applied to correct the measured position of mobile unit  10 -i to obtain the actual position of mobile unit  10 -i. 
     When using delta-pseudo-range method  42 , one of correction stations  37  receives code sequences from the GPS satellites  43  just as in correction factor method  40 . However, instead of obtaining the position fix as in correction factor method  40 , one of correction stations  37  calculates a first set of pseudo-ranges based on the code sequences  46 . The correction station also calculates a second set of pseudo-ranges  47  based on its position and the relative positions of GPS satellites  2 . Delta-pseudo-ranges are computed in step  48  using the two sets of pseudo-ranges and stored in correction table  36 . 
     Using the delta-pseudo-ranges or the delta-fixes stored in correction table  36 , data processing unit  30  of server  6  computes the actual positions of mobile units  10 - 1  through  10 -n. The computed positions are stored in position table  34 , to be accessed by data processing unit  30  for deriving the acceleration values of mobile units  10 - 1  through  10 -n. Acceleration value, as used herein, refers to the absolute value of acceleration. Acceleration of mobile unit  10 -i may be positive or negative depending on the direction of the collision. For example, when the collision is a head-on collision, the acceleration is negative. On the other hand, when the collision is a rear-ending accident that pushes mobile unit  10 -i forward, the acceleration is positive. When an acceleration value of a mobile unit is compared to a threshold value, it is herein implied that both values are discussed in terms of absolute value. 
     FIG. 4 shows another embodiment of the present invention. In the embodiment shown in FIG. 4, mobile unit  10 -i includes microprocessor  13 -i in addition to GPS receiver  12 -i and network transmitter  14 -i. Microprocessor  13 -i, which carries out substantially the same functions as server  6  of the embodiment in FIG. 1, derives the acceleration value of mobile unit  10 -i at a predetermined time interval and compares the acceleration value with the threshold value for  10 -i. Microprocessor  13 -i may include a memory space for storing the data for a given period of time and a map storage. When the acceleration value exceeds the threshold value, network transmitter  14 -i sends a notification to monitor unit  8  through data network  4 . There is no server  6  in the embodiment of FIG. 4 because all the functions of server  6  is carried out internally by mobile unit  10 -i. Optionally, the time interval between successive updates may be reduced after the detection of an acceleration value greater than the threshold value. The shortened time interval at the time of abnormal acceleration provides more data points for a subsequent accident analysis. 
     FIG. 5 shows an exemplary implementation of position table  34  which contains the position, the velocity, and optionally the acceleration of each mobile unit  10 - 1  through  10 -n. Columns  50  through  55  of position table  34  contain the actual position, velocity, and acceleration of each mobile unit  10 - 1  through  10 -n for a specific duration of time at discrete time intervals. In an embodiment that uses server  6 , each mobile unit  101  through  10 -n is identified by an identification number in column  50 . Column  50 , however, is unnecessary for the embodiment of FIG. 4 in which a microprocessor internal to the mobile unit is used instead of a remote server such as server  6 . Columns  51 ,  52 ,  53 ,  54 , and  55  contain rows that shift up each time a new set of data is added. The oldest set of data in position table  34  becomes deleted every time the most recent set of data is added. As a result, position table  34  stores the data representing the reported position, velocity, and acceleration for mobile units  10 - 1  through  10 -n during the most recent predetermined duration of time. The specific duration may be fixed, for example as  2  minutes, or may be selectable either through monitor unit  8  or through mobile unit  10 - 1  through  10 -n. 
     The mobile unit positions stored in column  52  of position table  34  are obtained by using either the correction factor method  40  or the delta-pseudo-range method  42 . The velocities in column  53  are obtained by dividing the change in position between two consecutive measurements by the time interval between the two consecutive measurements. The acceleration data stored in column  54  are obtained by dividing the velocities of two consecutive rows by the time interval. The threshold values stored in column  55 , which depend on various parameters of the mobile units, is obtained from either a separate database (e.g., database  40 ) or a database internal to server  6  (e.g., database  38 ). 
     Threshold value table  60  of FIG. 6 is an exemplary table of threshold values. Column  61  of threshold acceleration table  60  stores the same list of mobile unit identification numbers as column  50  of position table  34 . Threshold value, as used herein, refers to the highest rate of acceleration possible using the brakes or the accelerator of a motor vehicle. Therefore, an acceleration rate higher than the threshold value implies that an external force, such as a collision, is involved. In column  62 , threshold acceleration table  60  stores the vehicle type for each mobile unit  10 - 1  through  10 -n. Vehicle type may be, for example, the make and model of the vehicle, or a number that indicates a specific combination of parameters including but not limited to the vehicle weight, the type and age of the tires on the vehicle, and the type of braking system being used. Road conditions may also be taken into account. Column  63  of threshold acceleration table  60  records the threshold value that corresponds to each vehicle type. In some embodiments, there might be more than one threshold value. For example, there might be a threshold value for a collision, a threshold value for a free fall, and a threshold value for a roll-over. When the acceleration value of a mobile unit matches any of the threshold values, an accident notification is sent. 
     In some embodiments, the threshold values may not be in a table format. Instead, the threshold values may simply be calculated based on the specific vehicle parameters that are stored in a database (e.g., database  40  shown in FIG.  1 ). FIG. 1 shows that server  6  has access to database  40 . As mentioned above, database  40  may contain threshold acceleration table  60 . If threshold value is not stored in a table format, database  40  may contain, for each mobile unit, the parameters necessary for determining the threshold values, 
     A rate of acceleration that is higher than the threshold acceleration is hereinafter referred to as abnormal acceleration. For each mobile unit, position table  34  may continue updating the data only for a limited period of time after detecting an abnormal acceleration. For example, position table  34  may be programmed to record the position, the velocity, and the acceleration data for one minute after the detection of an abnormal acceleration. After a limited period of time, the updating stops and the data remains frozen. The frozen data contains the movement of mobile unit  10 -i for a given period of time prior to the collision and a given period of time after the collision. Later, the information about the movement of mobile unit  10 -i may help analyze the cause of collision. For example, the frozen data in position table  34  may be replace or supplement the skidmark analysis currently used for accident reports. Mobile unit  10 -i may be encased in a protective shell so as to minimize the probability of destruction upon a collision. Position table  34  may be programmed to record the position, the velocity, and the acceleration at a shorter time interval after a detection of an abnormal acceleration to provide more data points for subsequent accident analysis. 
     Upon detecting an abnormal acceleration, data processing unit sends an accident notification to monitor unit  8 . The notification may include text, images, sound, or a combination thereof Optionally, mobile unit  10 -i may be coupled to the collision-detection apparatus that deploys the air bags. In that case, server  6  may send a signal to deploy the air bags of mobile unit  10 -i upon detecting an abnormal acceleration. 
     Server  6  may include database  38  and map storage  32 . Database  38  may include information concerning, for example, the hospital and the police station nearest mobile unit  10 -i, road conditions, and traffic conditions. Storage for database  38  can be implemented using any mass storage media such as hard disks, RAMs, ROMs, CD-ROMs, and magnetic tapes. Perhaps, infrequently updated information (e.g., maps, nearest police station) may be stored on CD-ROMs, while frequently updated information (e.g., traffic conditions) can be stored on RAM. 
     When server  6  detects an abnormal acceleration, it sends an accident notification to monitor unit  8  through data network  4 . Monitor unit  8  may be, for example, a conventional computer with a web browser. An accident notification may involve text, audio, or graphics. In FIG. 7, exemplary accident notification  70  includes sufficient information to allow the operator of monitor unit  8  to estimate the severity of injuries accident victims may have sustained. In fact, server  6  can be programmed to recognize specific movement patterns as a certain type of accident. For example, a certain type of movement of mobile unit  10 -i may be recognized as a vehicle roll-over. Similarly, a certain type of acceleration pattern after the first abnormal acceleration may indicate multiple collisions. When the detected change in acceleration fits one of the recognized patterns, the accident type may be included in the accident notification. 
     Accident notification  70  of FIG. 7 not only provides the time at which abnormal acceleration was detected but also indicates position  77  of mobile unit  10 -i superimposed on map  76 . In addition, accident notification  70  may include vehicle information  72  such as the velocities of the mobile unit(s) (which is the same as velocities of the vehicles), the vehicle type, and the identification of the owner. The velocities and the positions of the mobile unit may allow an estimate of the severity of injuries to vehicle passengers. If the collision occurred at a high velocity, the police and the nearest hospital may need to be notified. In embodiments having multiple threshold values, accident notification  70  may also state the type of accident, for example a collision or a free fall, based on which threshold value was exceeded. Accident notification  70  may also provide peripheral data  78  concerning the nearest police station and the nearest hospital to expedite the dispatch of police cars or an ambulance. In case more information is necessary, window  74  of accident notification  70  allows monitor unit  8  to retrieve the data in position table  34 . Accident notification  70  may also include data on the traffic condition and road condition around the accident site so that any police car or ambulance can take the most efficient route to the accident site. To further expedite the process, monitor unit  8  may be located in a hospital or a police station. 
     If mobile unit  10 -i is coupled to the apparatus that deploys the air bag, the air bag deployment status can be included in accident notification  70 . Mobile unit  10 -I can be adapted to connect into the vehicle&#39;s diagnostic an operational status reporting system so that the operational condition of the vehicle at the time of the accident can be reported. For example, such as system can detect whether any seat belt is being used so that accident notification  70  can include information about whether seatbelts were being used in the vehicle. 
     Although the present invention is described using the above embodiments, the scope of the invention is not limited by the embodiments provided herein. Numerous variations and modifications are possible within the scope defined by the following claims.