Patent Publication Number: US-2007096974-A1

Title: Blending of sensors to produce alternate sensor characteristics

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      The application claims priority to U.S. Provisional Application No. 60/728,003 which was filed on Oct. 14, 2005. 
    
    
     BACKGROUND OF THE INVENTION  
      This invention generally relates to a method of sensing data in different ranges. More particularly, this invention relates to a method of obtaining sensor data within a desired range with fewer sensors.  
      Sensors are utilized in many applications for obtaining data indicative of vehicle performance and conditions. A sensor includes a range and resolution in which data can be gathered. A wider range will usually require a sacrifice in resolution. Greater resolution can also limit the range at which a sensor can accurately collect data. Specific applications and data gathering applications require different ranges and resolution. Such different applications and data requirements often require the use of multiple sensors of different resolutions and ranges.  
      Occupant protection systems rely on sensors to detect when actuation of safety devices should be activated. Typically a vehicle will include a high range sensor disposed at outer points of the vehicle in order to detect a major impact condition. A mid-range sensor is typically required to detect front or side impacts. Mid-range sensors are in some instances located within a controller of the occupant protection system. Still another sensor with a low range is required for stability control and sensing.  
      Disadvantageously, each sensor requires supporting hardware and programming. Further, the different sensors all contribute to the overall cost of the vehicle.  
      Accordingly, it is desirable to design and develop a method and system that provides the same data required to detect vehicle performance and conditions with fewer sensors.  
     SUMMARY OF THE INVENTION  
      A method and system generates data within a range without a sensor specifically allotted for that range by combining data within other ranges gathered by sensors of different ranges and resolutions.  
      Multiple sensors are utilized in different ways to detect different conditions. Algorithms for detecting front and side crash events require a mid-range acceleration sensor. The range of data gathered and utilized by an electronic control unit (ECU) from a mid-range sensor is around 50 g. The same algorithms also utilize data provided by satellite sensors disposed at the outer perimeter of the motor vehicle. The ECU also includes a low-range acceleration sensor that is utilized to provide data for traction or stability control functions and systems of the vehicle. Although each system utilizes acceleration data, that data is required within different ranges and resolutions and therefore require data within a specific range and resolution. For example, data from high range, mid-range and low-range sensors are required.  
      The example system uses high range satellite sensors, and the low range sensor to obtain a first set of data in the high range and a second set of data in the low range. The first set of data and the second set of data are utilized to produce a third set of data within the middle range without a mid-range sensor. The mid-range acceleration data is obtained by combining high-range data from the high-range satellite sensors, and low-range data from the low-range sensor disposed within the ECU.  
      Accordingly, the disclosed example method steps and system provides a method of producing data within a desired range using data gathered by sensors not optimal for the desired range. Further, the method produces desired data in a desired range without requiring additional sensors and the corresponding support hardware and programming that necessarily accompany additional sensors.  
      These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic illustration of an example system for detecting vehicle acceleration.  
       FIG. 2  is a graph illustrating example data ranges produced according to a disclosed example method.  
       FIG. 3  is a flow diagram illustrating example method steps for producing sensor data. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to  FIG. 1 , a vehicle  10  is schematically shown and includes a collision detection system  12 . The collision detection system  12  includes an electronic control unit (ECU)  14  for controlling specific vehicle functions. Multiple sensors are utilized in different ways to detect different conditions. Algorithms for detecting front and side crash events require a mid-range acceleration sensor. The range of data gathered and utilized by the ECU  14  from a mid-range sensor is around 50 g. The same algorithms also utilize data provided by satellite sensors  16 , 18 , 20 , 22  disposed at the outer perimeter of the motor vehicle  10 .  
      The ECU  14  also includes a low-range acceleration sensor  24  that is utilized for other systems within the vehicle, such as traction or stability control systems, for example. Each of the example sensor, although all measuring acceleration, supply data within a specific desired range and resolution to provide for the specific system functions. Accordingly, data from high range, mid-range and low-range sensors are required.  
      Referring to  FIG. 2 , a graph  50 , illustrates an example of acceleration data gathered by the various sensors within the vehicle  10 . A low range of data  52  provides acceleration data up to about 5 g. This low range  52  provides high resolution compared to satellite sensors that must be capable of sensing data in the high range  54 . A middle range  56  is utilized in concert with the data within the high range  54  to determine how the system  12  is activated.  
      The example system  12  uses high range satellite sensors  16 ,  18 ,  20 , and  22  and the low range sensor  24  to obtain a first set of data  60  in the high range  54  and a second set of data  62  in the low range. The first set of data  60  and the second set of data  62  are utilized to produce a third set of data  58  within the middle range  56 .  
      The example system eliminates the need for a mid-range sensor by generating the mid-range acceleration data by combining high-range data from high-range satellite sensors, and low-range data from the low-range sensor  24  disposed within the ECU  14 .  
      The satellite sensors  16 ,  18 ,  20 , and  22  provide a high-range of acceleration detection, at a low resolution as compared to the resolution provided by the low-range sensor  24  disposed within the ECU  14 . The low-range sensor  24  provides a relatively low-range of acceleration detection, for example about 5 g. The system  12  does not include a mid-range sensor. Acceleration data gathered from the low-range sensor  24  and the high-range satellite sensors  16 , 18 , 20 , 22  are combined to provide the mid-range data desired for operation of the system  12 .  
      Referring to  FIG. 3 , a schematic diagram illustrates example method steps to obtain mid-range acceleration data without a mid-range acceleration sensor and begins by first obtaining data from both the satellite sensors  16 ,  18 ,  20 , and  22  and the low range sensor  24  as indicated at  32 ,  34  and  36 . The data from the satellite sensors  16 ,  18 ,  20  and  22  is verified by a bounded average  38  to compensate for possible affects of local abuse.  
      Satellite sensors are necessarily disposed at the outer perimeter of the vehicle and therefore are susceptible to local conditions that can register as a very high local acceleration. For example, a shopping cart collision or door slam can cause a local disturbance that would register as an extreme acceleration, but only on one side of the vehicle  10 . Accordingly, data from the satellite sensors is weighted based on data gathered indicative of amplitude by the low range sensor  24  in the ECU  14  as is indicated at  40 .  
      An example weighting is shown at  41  and includes a proportioning factor that is applied responsive to the detected condition. In the illustrated example, a different proportioning factor is applied responsive to the acceleration data gathered by the low-range sensor in the ECU  14 . In the illustrated example, a high satellite sensor reading is combined with a low satellite reading depending on the amplitude of the acceleration at the ECU  14 . For example, data gathered from the left satellite sensor  20  is combined with data gathered from the right satellite sensor  16 . If the reading at the ECU  14  is substantially zero, the high reading is essentially disregarded and the low sensor reading is utilized. In a condition were the acceleration at the ECU  14  is at an upper end or maxed out in the lower range, the high satellite reading is weighted more.  
      Acceleration at the ECU  14  that is neither zero or maxed out, but is instead somewhere in the middle is weighted as a proportion of each of the high satellite reading and the low satellite reading. In the illustrated example there are two ranges illustrated that weight the high satellite reading with the low satellite reading according to a desired proportioning. Additional ranges can be utilized to further tailor the satellite acceleration data utilized in producing the desired mid-range sensor data.  
      Once the bounded average is obtained as indicated at  38  it is combined with low range sensor data as is indicated at  42 . In this step, the low range acceleration data is combined, not just utilized to determine a weighted value of high and low sensors as was performed in steps  40  and  41 .  
      Acceleration data from the low range acceleration sensor is combined with the data gathered from the high range acceleration sensor according to a weighting assigned to each data set depending on a magnitude of acceleration detected at the ECU  14 . The greater the acceleration values as the ECU  14 , the greater the weighting of the high range satellite acceleration sensors. The different ranges are applied incrementally to the data set to blend a first set of data produced as the bounded average of the satellite acceleration sensors, and a second data set produced by the low-range acceleration sensor  24  disposed within the ECU  14 .  
      The first range is selected when there is no acceleration or signal detected at the ECU  14 . In this instance, no weight is accorded the satellite sensor with the highest reading. A second range is selected and utilized when an acceleration value or signal is greater than the capability of the sensor within the ECU  14 , such that the acceleration value has maxed out the low-range sensor capacity. In this instance, the second range provides for a greater weighting on data obtained from the high range acceleration sensor, and no weight accorded the data from the low-range sensor  24 .  
      A third range is applied when data at the ECU  14  falls somewhere between the zero and the upper limit. In the third range, data from the high-range sensor is accorded a 20% weighting with the remaining 80% being applied and made up of data from the low-range acceleration sensor. In a fourth range, data from the high-range sensor and the low range sensor are accorded equal weighting. It should be understood that the example ranges can be added to or modified to obtain desirable weightings of data obtained from the different sensors to produce mid-range sensor data as desired.  
      The weighted values from the low-range sensor and the high-range sensor are then combined to provide desired data in a mid-range. Mid-range data is therefore provided without an actual sensor and can be utilized just as would otherwise be utilized if obtained directly from an actual sensor.  
      The method has been described and illustrated by way of specific example to producing vehicle acceleration data within a mid-range. However, other systems may utilize this method to produce data without sensors utilizing data gathered from other sensors of bounded ranges. Accordingly, the disclosed example method steps provide a method of producing data within a desired range using data gathered by sensors not optimal for the desired ranges. Further, the method produces desired data in a desired range without requiring additional sensors and the corresponding support hardware and programming that necessarily accompany additional sensors.  
      Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.