Abstract:
An exemplary navigation system uses a master navigation component at a first location with a first sensor in a vehicle and a slave navigation component with a second sensor at a second location that is a variable displacement to the first location due to physical deformation of the vehicle. Static and dynamic location components provide static and dynamic information of the displacement between the first and second locations. A flexural model based on the deformation characteristics calculates the dynamic displacement. An error estimator estimates errors in the navigation measurement data of the slave navigation component based on the displacement information. The master navigational component corrects the navigation measurement data of the slave navigation component based on the determined error, translates the corrected navigation measurement data of the slave navigation component into navigation measurement data in its coordinate system, and combines the output of the second sensor based on the corrected navigation measurement data with the output of the first sensor into a combined result.

Description:
BACKGROUND  
       [0001]     Multiple sensors of a sensing system are distributed in a vehicle to provide enhanced measurement capabilities and resolution of data by common observation of one or more emitters, transmitters, or reflectors, for example, a common target. The common target in one example comprises a vehicle, a ground installation, or a satellite. Through techniques such as interferometry, the multiple sensors determine one or more parameters of the common target, for example, location and/or shape of the common target. The accuracy to which the multiple sensors determine the parameters of the common target depends how accurately the location of each of the multiple sensors is known. The vehicle comprises a high performance navigation system to provide velocity, position, and attitude of the vehicle relative to a reference coordinate system. The navigation system is mounted in the vehicle but is usually physically separated from the sensors. The navigation system establishes navigation and orientation solutions for the vehicle relative to the reference coordinate system.  
         [0002]     The positions of the sensors are calculated based on known static rigid distances between the navigation system and the sensors and the navigation and orientation solutions for the vehicle. As the vehicle is in motion, the vehicle bends. The bending of the vehicle causes instantaneous discrepancies between the position expressed by the master navigation system and the position experienced by the sensor. The difference between the position expressed by the master navigation system and the position experienced by the sensor is the “lever arm error.” The lever arms between the master navigation system and the sensing systems are nominally known. As one shortcoming, due to bending of the vehicle, errors are induced into the velocity, position, and orientation of the sensing system where outputs of the master navigation system are corrected based on the nominal lever arms.  
         [0003]     One prior art solution to reduce the level arm error is to employ a smaller, lightweight, lower performance navigation system at the sensors of the sensing system. The navigation system at the sensors determines the velocity, position, and attitude of the sensors in a coordinate system relative to the sensors. As yet another shortcoming, the coordinate system defined by the navigation system at the sensor may differ from the coordinate system defined by the navigation system of the vehicle. As yet another shortcoming, spatial constraints of the vehicle may prohibit the addition of navigation systems at all the sensors. It is desirable to determine the position of all the sensors to obtain accurate measurements from all the sensors.  
         [0004]     Thus, a need exists for accurately determining positions of all sensors in a vehicle while the vehicle is in motion. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0005]     Features of exemplary implementations of the invention will become apparent from the description, the claims, and the accompanying drawings in which:  
         [0006]      FIG. 1  is a representation of one implementation of an apparatus that comprises one or more vehicles, one or more master navigation components, one or more slave navigation components, one or more sensors, one or more external positioning components, one or more flexural model components, and one or more intermediate location determination components.  
         [0007]      FIG. 2  is a representation of an exemplary process flow for providing corrected navigational parameters for the sensors from the master navigation component to the slave navigation components of the apparatus of  FIG. 1 .  
         [0008]      FIG. 3  is a representation of one implementation of one or more reference coordinate components and one or more rigid lever arm model components of the master navigation component, the slave navigation components, the sensors, the external positioning components, one or more incremental dynamic lever arm correction components, and one or more filters of the apparatus of  FIG. 1 .  
         [0009]      FIG. 4  is a representation of an exemplary process flow of calculating relative positions of the sensors of the apparatus of  FIG. 1 .  
         [0010]      FIG. 5  is another representation of the apparatus of  FIG. 1  comprising one or more navigation networks.  
         [0011]      FIG. 6  is a representation of another implementation of the navigation network of the apparatus of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0012]     Turning to  FIG. 1 , an apparatus  100  in one example comprises one or more vehicles  105 , one or more master navigation components  110 , one or more flexural model components  112 , one or more intermediate location determination components  114 , one or more slave navigation components  115 ,  120 ,  125 , and  130 , one or more sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156 , and one or more external positioning components  155  and  160 . The vehicle  105  in one example comprises a car, a tank, an airplane, an airship, or a space vehicle. The master navigation component  110  in one example comprises a high performance navigation system to provide velocity, position, and attitude of the vehicle  105 . The master navigation component  110  employs accelerometers and gyroscopes to determine the velocity, position, and attitude of the vehicle  105 . For example, the master navigation component  110  comprises an Inertial Navigation System (“INS”).  
         [0013]     The slave navigation components  115 ,  120 ,  125 , and  130  in one example comprise one or more inertial sensors, for example, three linear accelerometers and three gyroscopes, to determine position and attitude of the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156 . For example, the slave navigation components  115 ,  120 ,  125 , and  130  comprise one or more Inertial Measurement Units (“IMUs”), as will be understood by those skilled in the art. The slave navigation components  115 ,  120 ,  125 , and  130  and the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  are located in the vehicle  105 . For example, the slave navigation components  115 ,  120 ,  125 , and  130  and the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  are located along the edge of a wing of an airplane. The sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  comprise one or more synthetic aperture radars, one or more optical sensors, or one or more acoustic sensors. The sensors  135 ,  140 ,  145 , and  150  in one example are associated with the slave navigation components  115 ,  120 ,  125 , and  130 , respectively. The sensors  152 ,  154 , and  156  in one example are located in between one or more of the sensors  135 ,  140 ,  145 , and  150 . The master navigation component  110 , the slave navigation components  115 ,  120 ,  125 , and  130 , the flexural model component  112 , and the intermediate location determination component  114 , comprise an instance of a recordable data storage medium  101 , as described herein.  
         [0014]     The flexural model component  112  comprises a model that describes the flexing, or bending, of the structure of the vehicle  105  as a function of time while the vehicle  105  is in motion. Based on estimations of the positions of the slave navigation components  115 ,  120 ,  125 , and  130 , the flexural model component  112  expresses the relative displacement of any point along the structure of the vehicle. For example, the flexural model component  112  takes as input one or more lever arm parameters  194  of the distances between the master navigation component  110  and the slave navigation components  115 ,  120 ,  125 , and  130  as a function of time. The flexural model component  112  comprises one or more equations describing the reaction of the vehicle  105  during motion. For example, the flexural model component  112  comprises equations describing the bending of the structure of the vehicle  105  as a function of time. The flexural model component  112  applies lever arm parameters  194  to the equations to generate an equation describing the relative displacement of any sensor along the structure of the vehicle  105  as a function of time. In one example, the flexural model component  112  is programmed with the equations describing the bending of the structure of the vehicle  105  as a function of time. In another example, the flexural model component  112  employs one or more neural networks that cooperate to describe displacement of the sensors  135 ,  140 ,  145 , and  150  relative to one another. The flexural model component  112  provides as output  191 , equations describing the relative displacement of any sensor along the structure of the vehicle  105  as a function of time.  
         [0015]     The intermediate location determination component  114  determines positions of sensors that are not associated with a slave navigation component, for example, the sensors  152 ,  154 , and  156 . The intermediate location determination component  114  determines the relative position of a sensor in relationship to one or more sensors associated with a slave navigation component. The intermediate location determination component  114  applies the relative position of the sensor to the equation describing the relative displacement of any sensor along the structure of the vehicle  105  to produce the position of the sensor relative to a coordinate system established by the master navigation component  110 . The external positioning components  155  and  160  in one example comprise a Global Positioning System (“GPS”) receiver and a baro-altimeter, respectively.  
         [0016]     The master navigation component  110  employs one or more sensors to determine navigation measurement data for the vehicle  105 . The navigation measurement data for the vehicle  105  in one example comprises: inertial measurement data, positioning measurement data, air speed measurement data, and/or pressure altitude measurement data. In one example, the master navigation component  110  employs one or more inertial sensors to determine inertial measurement data for the vehicle  105 . In another example, the master navigation component  110  employs one or more pressure altitude sensors to determine pressure altitude measurement data for the vehicle  105 . In yet another example, the master navigation component  110  employs one or more GPS units to determine GPS measurements for the vehicle  105 . In yet another example, the master navigation component  110  employs one or more air speed sensors to determine air speed measurements for the vehicle  105 . The master navigation component  110  employs the navigation measurement data to determine a navigation and orientation solution for the vehicle  105  that describes the location/position of the vehicle  105  with respect to a reference coordinate system, for example, the Earth.  
         [0017]     The master navigation component  110  establishes a coordinate system, for example, a first coordinate system, with respect to the reference coordinate system based on the navigation measurement data for the vehicle  105 , as will be understood by those skilled in the art. In one example, the master navigation component  110  employs data from the external position component  155 , for example, GPS data, pressure altitude, or air data, to establish the coordinate system, as will be appreciated by those skilled in the art. In another example, the master navigation component  110  employs navigation measurement data from the slave navigation components  115 ,  120 ,  125 , and  130 , and positioning information from the external positioning components  155  and  160  to establish the coordinate system for the vehicle  105 . In yet another example, the master navigation component  110  employs the navigation measurement data from the slave navigation components  115 ,  120 ,  125 , and  130  to further refine the coordinate system established by the master navigation component  110  for the vehicle  105 . The master navigation component  110  employs the coordinate system and the navigation measurement data for the vehicle  105  to describe the orientation of the vehicle  105  as a function of time.  
         [0018]     The master navigation component  110  establishes a coordinate system, for example, a first coordinate system, with respect to the reference coordinate system based on the navigation measurement data for the vehicle  105 , as will be understood by those skilled in the art. The master navigation component  110  employs the coordinate system and the navigation measurement data for the vehicle  105  to describe the orientation of the vehicle  105  as a function of time. The master navigation component  110  in one example employs data from the external position component  155 , for example, GPS data, pressure altitude, or air data, to establish the coordinate system, as will be appreciated by those skilled in the art. In another exemplary embodiment of the apparatus  100 , the master navigation component  110  employs navigation measurement data from the slave navigation components  115 ,  120 ,  125 , and  130 , and positioning information from the external positioning components  155  and  160  to establish and further refine the coordinate system for the vehicle  105 .  
         [0019]     The master navigation component  110  communicates with the slave navigation components  115 ,  120 ,  125 , and  130  to describe the position of the sensors  135 ,  140 ,  145 , and  150  relative to the coordinate system established by the master navigation component  110 . The master navigation component  110  obtains navigation measurement data, for example, navigation measurement data, for the positions of the sensors  135 ,  140 ,  145 , and  150  as a function of time from the slave navigation components  115 ,  120 ,  125 , and  130 . The master navigation component  110  comprises one or more error estimation components, for example, one or more Kalman filters, to estimate one or more errors in the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130 . The master navigation component  110  corrects the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  based on the errors. The master navigation component  110  provides the corrected navigation measurement data to the slave navigation components  115 ,  120 ,  125 , and  130 , as illustrated by outputs  165 ,  170 ,  175 , and  180 . The slave navigation components  115 ,  120 ,  125 , and  130  employ the corrected navigation measurement data to improve estimations of navigation parameters (e.g., orientation, position, and velocity) of the sensors  135 ,  140 ,  145 , and  150 .  
         [0020]     The master navigation component  110  translates the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  from coordinate systems established by the slave navigation components  115 ,  120 ,  125 , and  130 , for example, one or more second coordinate systems, to the coordinate system established by the master navigation component  110 , for example, the first coordinate system, as will be appreciated by those skilled in the art. The master navigation component  110  provides navigational parameters for the master navigation component  110  as output  182 . The master navigation component  110  provides translated navigation parameters for the sensors  135 ,  140 ,  145 , and  150  in the coordinate system established by the master navigation component  110  as illustrated by the outputs  184 ,  186 ,  188 , and  190 . The master navigation component  110  provides the orientation of the coordinate reference system as output  192 .  
         [0021]     The master navigation component  110  estimates the lever arm parameters  194  (i.e. parameters used to model three dimensional distance vectors) between the master navigation component  110  and the slave navigation component  115 , the master navigation component  110  and the slave navigation component  120 , the master navigation component  110  and the slave navigation component  125 , and the master navigation component  110  and the slave navigation component  130 . The slave navigation components  115 ,  120 ,  125 , and  130  employ the estimation of the lever arms to determine dynamic motion of the sensors  135 ,  140 ,  145 , and  150  relative to the coordinate system established by the master navigation component  110 . The master navigation component  110  provides the lever arm parameters  194  to the flexural model component  112 .  
         [0022]     The master navigation component  110  synchronizes the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  as a function of time provided by the slave navigation components  115 ,  120 ,  125 , and  130  with the navigation measurement data of the master navigation component  110 . In one example, the slave navigation component  115  provides a timestamp along with navigation measurement data for the slave navigation component  115 . The master navigation component  110  compares the navigation measurement data for the slave navigation component  115  with the navigation measurement data of the master navigation component  110  at a time described by the timestamp. In another example, the master navigation component  110  and the slave navigation components  115 ,  120 ,  125 , and  130  operate on a synchronized clock, for example, a clock  162 . In yet another example, the master navigation component  110  and the slave navigation components  115 ,  120 ,  125 , and  130  employ timing pulses to synchronize the navigation measurement data of the master navigation component  110  with the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130 .  
         [0023]     The slave navigation components  115 ,  120 ,  125 , and  130  determine navigation parameters (e.g., orientation, position, and velocity) of the sensors  135 ,  140 ,  145 , and  150 . The slave navigation components  115 ,  120 ,  125 , and  130  compensate the output of the sensors  135 ,  140 ,  145 , and  150  based on the orientation, position, and/or velocity of the sensors  135 ,  140 ,  145 , and  150 . The slave navigation components  115 ,  120 ,  125 , and  130  communicate with the master navigation component  110  to provide the navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  to the master navigation component  110 . The slave navigation components  115 ,  120 ,  125 , and  130  receive corrected navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  from the master navigation component  110 . The slave navigation components  115 ,  120 ,  125 , and  130  employ the corrected navigation measurement data of the slave navigation components  115 ,  120 ,  125 , and  130  to describe the position of the sensors  135 ,  140 ,  145 , and  150  with respect to the coordinate system established by the master navigation component  110 . For example, the slave navigation component  115  employs the corrected navigation measurement data of the slave navigation component  115  to determine motion of the sensor  135  relative to the coordinate system established by the master navigation component  110 .  
         [0024]     An illustrative description of exemplary operation of the apparatus  100  is presented, for explanatory purposes.  
         [0025]     Turning to  FIG. 2 , in STEP  205 , the master navigation component  110  determines a navigation solution as a function of time for the vehicle  105 . In STEP  210 , the master navigation component  110  employs navigation measurement data and optional data from the external positioning component  155  to establish a coordinate system for the vehicle  105 , for example, a first coordinate system, in relation to the Earth. In STEP  215 , the master navigation component  110  receives navigation measurement data with respect to a coordinate system established by the slave navigation component  115 , for example, a second coordinate system, and time-tag from the slave navigation component  115  for the sensor  135 . The master navigation component  110  employs the time-tag to determine the navigation measurement data of the master navigation component  110  at a time described by the time-tag. In STEP  220 , the master navigation component  110  compares the navigation measurement data of the slave navigation component  115  at the time described by the time-tag to the navigation measurement data of the master navigation component  110  at the time described by the time-tag. The navigation measurement data of the master navigation component  110  at the time described by the time-tag in one example comprises navigation measurement data of the master navigation component  110  adjusted by one or more lever arms between the master navigation component  110  and the slave navigation components  115 ,  120 ,  125 , and  130 , as described herein.  
         [0026]     In STEP  225 , the master navigation component employs a Kalman filter to estimate errors in the navigation measurement data from the slave navigation component  115 . In STEP  230 , the master navigation component  110  corrects the errors in the navigation measurement data from the slave navigation component  115 . In STEP  235 , the master navigation component  110  translates the corrected navigation measurement data for the slave navigation component  115  from the coordinate system established by the slave navigation component  115 , (e.g., the second coordinate system) to the coordinate system established by the master navigation component  110  (e.g., the first coordinate system). In STEP  240 , the master navigation component  110  employs the corrected and translated navigation measurement data for the slave navigation component  115  in the first coordinate system to provide navigation parameters for the sensor  135 , for example, orientation, position, and velocity, in the coordinate system established by the master navigation component  110 .  
         [0027]     Turning to  FIG. 3 , the master navigation component  110  in one example comprises one or more reference coordinate components  305  and one or more rigid lever arm model components  310  and  340 . The reference coordinate component  305  establishes a coordinate system for the vehicle  105 . The rigid lever arm model component  310  comprises a base-line static position for the slave navigation component  115 . The rigid lever arm model component  310  determines a base-line static lever arm for the slave navigation component  115  based on the base-line static position. The base-line static lever arm for the slave navigation component  115  comprises a three-dimensional position distance, or vector, between the master navigation component  110  and the slave navigation component  1   5 . The rigid lever arm model component  310  cooperates with the reference coordinate component  305  to project the base-line static lever arm for the slave navigation component  115  into the coordinate system established by the reference coordinate component  305  to determine a translated static lever arm for the slave navigation component  115 . The rigid lever arm model component  310  sends the translated static lever arm for the slave navigation component  115  as output  316  to a summing node  318 .  
         [0028]     The slave navigation component  115  determines navigation measurement data for the slave navigation component  115  in reference to a coordinate system established by the slave navigation component  115 . The slave navigation component  115  sends as output  320 , the navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the slave navigation component  115  to the summing node  318 . The summing node  318  combines the output  316  from the rigid lever arm model component  310  with the output  320  from the slave navigation component  115  to produce as output  322 , navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305 .  
         [0029]     The output  322  comprising the navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305  is enhanced through employment of an incremental dynamic lever arm correction component  324 . The incremental dynamic lever arm correction component  324  comprises a model describing reactions of the vehicle  105  during motion. The incremental dynamic lever arm correction component  324  employs the model to provide positions for the slave navigation components  115  and  120  in relation to the reactions of the vehicle  105  during motion. For example, while in motion, the vehicle  105  reacts by bending. The bending of the vehicle  105  alters a lever arm (i.e., the three-dimensional distance vector) between the master navigation component  110  and the slave navigation component  115 . As the vehicle  105  bends, the lever arm between the master navigation component  110  and the slave navigation component  115  changes.  
         [0030]     The incremental dynamic lever arm correction component  324  receives as input, an output  326  from the reference coordinate component  305 , and an output  327  from the slave navigation component  115 . The output  326  comprises the coordinate system established by the reference coordinate component  305 . The output  327  comprises the navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the slave navigation component  115 , similar to the output  320 . The incremental dynamic lever arm correction component  324  employs the outputs  326  and  327  to determine a dynamic lever arm for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305 . The incremental dynamic lever arm correction component  324  sends as output  328 , the dynamic lever arm for the slave navigation component  115  to the summing node  318 . The summing node  318  combines the outputs  316 ,  320 , and  328  to produce the output  322 . Thus, the summing node  318  generates the output  322  as comprising more accurate navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305  for the vehicle  105  in motion. The output  328  of the incremental dynamic lever arm correction component  324  obtains more accuracy through employment of a filter  330 , for example, a Kalman filter, as will be discussed herein.  
         [0031]     The filter  330  receives as input, the output  322  from the summing node  318 . The filter  330  compares the output  322  for a given timestamp (i.e., the navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305 ) with the navigation measurement data from the reference coordinate component  305  at the given timestamp. The filter  330  estimates errors in the output  322 . The filter  330  provides as output  332 , corrected navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305 . The slave navigation component  115  employs the output  332  to determine orientation, position, and velocity of the sensor  135  with respect to the coordinate system established by the reference coordinate component  305 . The slave navigation component  115  employs the output  332  to adjust the coordinate system established by the slave navigation component  115 . In addition, the filter  330  sends as output  334 , the corrected navigation measurement data for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305  to the incremental dynamic lever arm correction component  324 . The incremental dynamic lever arm correction component  324  employs the output  334  to correct the output  328 , the dynamic lever arm for the slave navigation component  115 . Thus, the incremental dynamic lever arm correction component  324 , the slave navigation component  115  and the filter  330  cooperate to iteratively align a coordinate system of the slave navigation component  115  with the coordinate system established by the reference coordinate component  305 .  
         [0032]     The slave navigation component  120 , the sensor  140 , the reference coordinate component  305 , rigid lever arm model component  340 , summing node  348 , incremental dynamic lever arm correction component  354 , and outputs  346 ,  350 ,  352 ,  358 ,  357 ,  362 , and  364  interact in a similar fashion to the slave navigation component  115 , the sensor  135 , the reference coordinate component  305 , the rigid lever arm model component  310 , the summing node  318 , the incremental dynamic lever arm correction component  324 , outputs  316 ,  320 ,  322 ,  326 ,  327 ,  328 ,  332  and  334 . The reference coordinate component  305 , the rigid lever arm model components  310  and  315 , incremental dynamic lever arm correction components  324  and  354 , and the filter  330 , comprise one or more instances of a recordable data storage medium  101 , as described herein.  
         [0033]     Referring still to  FIG. 3 , the slave navigation component  115  sends as output  366 , the navigation measurement data for the slave navigation component  115  to the incremental dynamic lever arm correction component  354 . The incremental dynamic lever arm correction component  354  employs the output  366  to provide increased accuracy of the dynamic lever arm for the slave navigation component  120  in reference to the coordinate system established by the reference coordinate component  305 . The slave navigation component  120  sends as output  368 , the navigation measurement data for the slave navigation component  120  to the incremental dynamic lever arm correction component  324 . The incremental dynamic lever arm correction component  324  employs the output  368  to provide increased accuracy of the dynamic lever arm for the slave navigation component  115  in reference to the coordinate system established by the reference coordinate component  305 .  
         [0034]     Referring again to  FIG. 3 , the filter  330  receives as input, navigation measurement data from the master navigation component  110 , and the slave navigation components  115  and  120 . The filter  330  receives as input, output  370  from the reference coordinate component  305 , the output  322  from the slave navigation component  115 , and the output  352  from the slave navigation component  120 . The filter  330  employs the outputs  322 ,  352 , and  370  to establish a coordinate system. For example, the filter  330  combines the outputs  322 ,  352 , and  370  to establish the coordinate system, as will be appreciated by those skilled in the art. The filter  330  estimates errors in navigation measurement data received from the reference coordinate component  305 , and the slave navigation components  115  and  120 , and corrects the errors.  
         [0035]     The filter  330  sends as output  372 , the corrected navigation measurement data with respect to the coordinate system established by the filter  330  to the reference coordinate component  305 . The reference coordinate component  305  employs the output  372  to adjust a coordinate system established by the reference coordinate component  305 . For example, the reference coordinate component  305  employs the output  372  to adjust a base-line coordinate system established by the reference coordinate component  305 . The filter  330  and the reference coordinate component  305  cooperate to align the coordinate system established by the reference coordinate component  305  and the coordinate system established by the filter  330 . The filter  330  sends the outputs  332 ,  334 ,  362 , and  364 , the corrected navigation measurement data with respect to the coordinate system established by the filter  330  to the slave navigation components  115  and  120 , and the incremental dynamic lever arm correction component  324  and  354 .  
         [0036]     Turning to  FIGS. 1 and 4 , for example, the sensor  152  comprises an intermediate sensor, for example, the sensor  152  is located between the sensors  135  and  140 . In STEP  405 , the intermediate location determination component  114  obtains the location of the sensors  135  and  140  relative to the coordinate system established by the master navigation component  110 . In STEP  410 , the intermediate location determination component  114  calculates a relative location of the sensor  152  with respect to the sensors  135  and  140 . In STEP  415 , the intermediate location determination component  114  applies the relative location of the sensor  152  to the equation describing the relative displacement of any sensor along the structure of the vehicle  105 . In STEP  420 , the intermediate location determination component  114  obtains the location of the sensor  152  in the coordinate system established by the master navigation component  110 . Upon determining the location of the sensor  152 , measurement data obtained by the sensor  152  is compensated to reflect the motion of the sensor  152  as a function of time. Compensating measurement information obtained by the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  improves the quality of the measurement information. Combining the compensated measurement information obtained by the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156 , for example, combining signals received by the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  at multiple locations through interferometric sensing processing and techniques, produces higher quality results, for example, higher quality image, as will be appreciated by those skilled in the art.  
         [0037]     Turning to  FIGS. 1, 4 , and  5 , the vehicle  105  comprises a navigation network  502 . The navigation network  502  comprises a navigation network hub  510 , and one or more navigation components  515 ,  520 ,  525 ,  530 , and  532 . The navigation components  515 ,  520 ,  525 ,  530 , and  532  in one example comprise navigation components of varying degrees of accuracy. For example, the navigation components  515 ,  520 , and  525  comprise high performance navigation systems, similar to the master navigation component  110 , and the navigation components  530  and  532  comprise lower performance navigation systems, similar to the slave navigation components  115 ,  120 ,  125 , and/or  130 . The navigation components  515 ,  520 ,  525 ,  530 , and  532  obtain navigation measurement data for the navigation components  515 ,  520 ,  525 ,  530 , and  532 . The navigation components  515 ,  520 ,  525 ,  530 , and  532  cooperate to determine navigation parameters (i.e., orientations, positions, and velocities) for sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156 .  
         [0038]     The navigation network hub  510  in one example receives navigation measurement data from the navigation components  515 ,  520 ,  525 ,  530 , and  532 . The navigation network hub  510  employs the navigation measurement data from the navigation components  515 ,  520 ,  525 ,  530 , and  532  to establish a coordinate system, for example, a first coordinate system, for the vehicle  105 . The navigation network hub  510  determines one or more navigational parameters (i.e., orientations, positions, and velocities) for the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  with respect to the coordinate system established by the navigation network hub  510  (i.e., the first coordinate system). The navigation network hub  510  provides translated navigation parameters (i.e. orientations, velocities, and positions) of the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  in the coordinate system established by the navigation network hub  510  as illustrated by the outputs  582 ,  584 ,  586 ,  588 , and  590 . The navigation network hub  510  provides the orientation of the coordinate system established by the navigation network hub  510  as output  592 . The navigation network hub  510  provides lever arm parameters  594  to the flexural model component  112 . The flexural model component  112  applies the lever arm parameters  594  to equations describing the reaction of the vehicle  105  while in motion. The flexural model component  594  provides as output  591 , the equations describing the relative displacement of the sensors  135 ,  140 ,  145 , and  150  along the structure of the vehicle  105  as a function of time with respect to the coordinate system established by the navigation network hub  510 .  
         [0039]     The intermediate location determination component  514  employs the outputs  582 ,  584 ,  586 ,  588 , and  590  as well as the output  591  to determine navigation parameters for intermediate sensors, for example, the sensors  152 ,  154 , and  156 . For example, the output  591  describes the bending of the vehicle  105 . The outputs  582 ,  584 ,  586 ,  588 , and  590  describe the navigation parameters of the sensors  135 ,  140 ,  145 , and  150 . The intermediate location determination component  514  in one example comprises locations of the sensors  152 ,  154 , and  156 . The intermediate location determination component  514  employs the bending of the vehicle  105  (described by the output  594 ) to determine equations describing navigation parameters between sensors  135 ,  140 ,  145 , and  150 . From the equations describing the navigation parameters between the sensors  135 ,  140 ,  145 , and  150 , the intermediate location determination component  514  employs the location of the sensors  152 ,  154 , and  156  to determine navigation parameters for the sensors  152 ,  154 , and  156 . The navigation network hub  510  and the navigation components  515 ,  520 ,  525 ,  530 , and  532  comprise one or more instances of a recordable data storage medium  101 , as described herein.  
         [0040]     The navigation network hub  510  and the navigation components  515 ,  520 ,  525 , and  530  communicate through employment of one or more instances of a network bus  595 . In one example, the network bus  595  comprises a high speed transmission bus. In another example, the network bus  595  comprises an Ethernet communication means. The navigation components  515 ,  520 ,  525 , and  530  in one example employ the network bus  595  to transmit navigation measurement data to the navigation network hub  510 . In one example, the navigation network hub  510  employs the network bus  595  to transmit corrected navigation measurement data  565 ,  570 ,  575 , and  580  to the navigation components  515 ,  520 ,  525 , and  530 . In another example, the navigation network hub  510  employs the network bus  595  to provide outputs  582 ,  584 ,  586 ,  588 ,  590 , and  592 . In yet another example, the navigation network hub  510  employs the network bus  595  to communicate with the external positioning components  155  and  160 . The navigation network hub  510  employs a standard protocol over the network bus  595  to provide a common interface to multiple external components, for example, the navigation components  515 ,  520 ,  525 , and  530 , the external positioning components  155  and  160 , and one or more vehicle computers (not shown).  
         [0041]     Turning to  FIGS. 1 and 6 , the apparatus  100  comprises one or more vehicles  602 ,  604 ,  606 , and  608 , one or more master navigation components  610 ,  612 ,  614 , and  616 , one or more slave navigation components  618 ,  620 ,  622 , and  624 , one or more sensors  626 ,  628 ,  630 , and  632 , one or more common transmission component  634 , one or more communication links  636 ,  638 ,  640 ,  642 ,  644 , and  646 , and one or more control centers  650 . The vehicles  602 ,  604 ,  606 , and  608  communicate through employment of the vehicle communication links  636 ,  638 ,  640 , and  642 . The vehicles  602 ,  604 ,  606 , and  608  communicate with the control center  650  through employment of center communication links  611 ,  613 ,  615 , and  617 . The vehicle communication links  636 ,  638 ,  640 , and  642  and the data links  611 ,  613 ,  615 , and  617  in one example comprise satellite communications, tactical command data link (“TCDL”), Link  16 , and Advanced Information Architecture (“AIA”). The vehicles  602 ,  604 ,  606 , and  608  are similar to the vehicle  105  of the  FIG. 1 . The master navigation components  610 ,  612 ,  614 , and  616  are similar to the master navigation component  110  of the  FIG. 1 . The slave navigation components  618 ,  620 ,  622 , and  624  are similar to the slave navigation components  115 ,  120 ,  125 , and  130  of the  FIG. 1 . The sensors  626 ,  628 ,  630 , and  632  are similar to the sensors  135 ,  140 ,  145 ,  150 ,  152 ,  154 , and  156  of the  FIG. 1 .  
         [0042]     In one example, the vehicles  602 ,  604 ,  606 , and  608  comprise one or more unmanned vehicles, for example, unmanned airplanes, monitoring the common target  634 . For example, the common target  634  comprises a satellite, an object on the ground, a vehicle, a radio emitter, or an acoustic emitter. The control center  650  obtains measurement data from the sensors  626 ,  628 ,  630 , and  632  of the vehicles  602 ,  604 ,  606 , and  608 . The control center  650  combines the measurement data using interferometric techniques to produce an enhanced representation of the common target  634 .  
         [0043]     The master navigation components  610 ,  612 ,  614 , and  616  employ the vehicle communication links  636 ,  638 ,  640 , and  642  to establish a navigation network  601 . The master navigation components  610 ,  612 ,  614 , and  616  communicate through employment of the navigation network  601  to establish a coordinate system relative to a reference coordinate system for the vehicles  602 ,  604 ,  606 , and  608 . The master navigation components  610 ,  612 ,  614 , and  616  employ timestamps to establish the coordinate system through employment of the navigation network  601 . For example, the master navigation component  610  associates a timestamp with navigation measurement data for the master navigation component  610 . The master navigation component  610  employs the communication link  642  to provide the timestamp with the navigation measurement data for the master navigation component  610  to the master navigation component  614 . The master navigation component  614  employs the timestamp to compare the navigation measurement data for the master navigation component  610  with navigation measurement data for the master navigation component  614  at a time described by the timestamp. The master navigation components  610 ,  612 ,  614 , and  616  employ one or more of: a common clock, an atomic clock, or GPS time to timestamp the measurement data.  
         [0044]     The master navigation components  610 ,  612 ,  614 , and  616  employ the Earth as the reference coordinate system. The master navigation components  610 ,  612 ,  614 , and  616  determine navigation and orientation solutions for the vehicles  602 ,  604 ,  606 , and  608 . For example, the master navigation components  610 ,  612 ,  614 , and  616  each establish a coordinate system for the vehicles  602 ,  604 ,  606 , and  608 , respectively. The master navigation components  610 ,  612 ,  614 , and  616  establish the coordinate systems with respect to a reference coordinate system, for example, the Earth. In one example, the master navigation components  610 ,  612 ,  614 , and  616  employ the reference coordinate system as the coordinate systems established by the master navigation components  610 ,  612 ,  614 , and  616 . In another example, the master navigation components  610 ,  612 ,  614 , and  616  cooperate to establish a common coordinate system used by each of the master navigation components  610 ,  612 ,  614 , and  616 . The master navigation components  610 ,  612 ,  614 , and  616  employ the common coordinate system to transpose their individual navigation parameters into the common coordinate system.  
         [0045]     The sensors  626 ,  628 ,  630 , and  632  obtain measurement data on the signals from the common target  634 . The master navigation components  610 ,  612 ,  614 , and  616  translate the measurement data from a coordinate system established by the slave navigation components  618 ,  620 ,  622 , and  624  into the coordinate system established by the master navigation components  610 ,  612 ,  614 , and  616 . The vehicles  602 ,  604 ,  606 , and  608  employ the data links  611 ,  613 ,  615 , and  617  to send the measurement data on the signals to the control center  650  in the coordinate system established by the master navigation components  610 ,  612 ,  614 , and  616 . The control center  650  employs the measurement data from the sensors  626 ,  628 ,  630 , and  632  in the coordinate system established by the master navigation components  610 ,  612 ,  614 , and  616  to perform interferometric sensing across the vehicles  602 ,  604 ,  606 , and  608 . For example, the control center  650  employs an interferometric technique to calculate phase differences between the signals received by the sensors  626 ,  628 ,  630 , and  632  with respect to the coordinate system established by the master navigation components  610 ,  612 ,  614 , and  616 . Based on the phase differences, the control center  634  determines information, for example, orientation, position, velocity, and shape, of the common target  634 . Through employment of the coordinate system established by the master navigation components  610 ,  612 ,  614 , and  616 , the control center  650  relates the signals received by the sensors  626 ,  628 ,  630 , and  632  to an accurate absolute position. The control center  650  employs the accurate absolute position to provide a geolocation or position for the common target  634 .  
         [0046]     The apparatus  100  in one example comprises a plurality of components such as one or more of electronic components, hardware components, and computer software components. A number of such components can be combined or divided in the apparatus  100 . An exemplary component of the apparatus  100  employs and/or comprises a set and/or series of computer instructions written in or implemented with any of a number of programming languages, as will be appreciated by those skilled in the art.  
         [0047]     The apparatus  100  in one example employs one or more computer-readable signal-bearing media. The computer-readable signal-bearing media store software, firmware and/or assembly language for performing one or more portions of one or more embodiments of the invention. Examples of a computer-readable signal-bearing medium for the apparatus  100  comprise the recordable data storage medium  101  of the master navigation component  110 , the slave navigation components  115 ,  120 ,  125 , and  130 , the flexural model component  112 , the intermediate location determination component  114 , the reference coordinate component  305 , the rigid lever arm model components  310  and  315 , incremental dynamic lever arm correction components  324  and  354 , the filter  330 , the navigation network hub  510 , and the navigation components  515 ,  520 ,  525 ,  530 , and  532 . The computer-readable signal-bearing medium for the apparatus  100  in one example comprise one or more of a magnetic, electrical, optical, biological, and atomic data storage medium. For example, the computer-readable signal-bearing medium comprise floppy disks, magnetic tapes, CD-ROMs, DVD-ROMs, hard disk drives, and electronic memory. In another example, the computer-readable signal-bearing medium comprises a modulated carrier signal transmitted over a network comprising or coupled with the apparatus  100 , for instance, one or more of a telephone network, a local area network (“LAN”), a wide area network (“WAN”), the Internet, and a wireless network.  
         [0048]     The steps or operations described herein are just exemplary. There may be many variations to these steps or operations without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified.  
         [0049]     Although exemplary implementations of the invention have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.