Abstract:
An exemplary system that provides for navigation redundancy includes first and second navigation components adapted to determine first and second navigation parameters, respectively. A network component determines a relationship between the first and second navigation components, wherein the relationship describes a navigation solution for the second navigation component in terms of the first navigation component. A health monitor determines a health indicator for the second navigation component. The second navigation component determines a navigation solution for the second navigation parameters when the health indicator indicates a healthy condition. The network component determines a navigation solution for the second navigation parameters based on the relationship that describes behavior of the second navigation component in terms of the first navigation component when the health indicator indicates an unhealthy condition.

Description:
BACKGROUND  
       [0001]     A vehicle, for example, an airplane, a land vehicle, or a space vehicle, comprises multiple sensing systems. The sensing systems comprise one or more navigation components and one or more sensors. In one example, the navigation components compensate outputs of one or more of the sensors. For example, the navigation components determine navigation parameters, for example, orientation, velocity, and position, for the sensors and compensate the output of the sensors based on the navigation parameters. As one shortcoming, where the navigation component experiences one or more failures, the output of the sensor is inaccurately compensated, producing erroneous navigation information.  
         [0002]     For example, in a synthetic aperture radar, an image is formed by combining received signals over a period of time while the radar is in motion. The navigation components determine navigation parameters for the sensors. The navigation components employ the navigation parameters to compensate the signals from the sensors. Where a navigation component is unable to determine navigation parameters for a sensor, the sensor provides erroneous signals, resulting in an inaccurate image.  
         [0003]     In another example, the navigation components determine navigation parameters, for example, orientation, velocity, and position, of the vehicle with respect to a reference coordinate system. As another shortcoming, where the navigation component is unable to calculate the navigation parameters for the vehicle, the vehicle is unable to navigate. For example, a rocket employs a Global Positioning System (“GPS”) unit to determine position of the rocket with respect to the Earth in order to calculate a flight path for the rocket. Upon occurrence of a failure in the navigation component, the rocket is unable to accurately calculate the flight path, and crashes into an undesirable location.  
         [0004]     Thus, a need exists for compensating outputs of sensors of sensing systems on a vehicle upon failure of one or more navigation components of the sensing systems. 
     
    
     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 navigation network processor components, one or more navigation systems, one or more navigation components, one or more sensors, and one or more external positioning components.  
         [0007]      FIG. 2  is a representation of one implementation of one or more navigation solution determination components, one or more expected values components, one or more standard navigation solution components, one or more replacement navigation solution components, one or more flexural model components of the navigation network processor component 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 navigation network processor component, the 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 for providing corrected navigational parameters for the sensors from the navigation network processor component to the navigation components of the apparatus of  FIG. 1 .  
         [0010]      FIG. 5  is another representation of an exemplary process flow for determining one or more health indicators of the navigation components, the navigation systems, and the sensors of the apparatus of  FIG. 1 .  
         [0011]      FIG. 6  is a representation of an exemplary process flow for determining one or more replacement navigation solutions for the navigation components, the navigation systems, and the sensors of the apparatus of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0012]     Turning to  FIG. 1 , an apparatus  100  in one example comprises one or more vehicles  105 , one or more navigation network processor components  110 , one or more navigation components  115 ,  120 ,  125 , and  130 , one or more navigation systems  152 ,  153 , and  154 , 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 navigation network component  110  establishes a coordinate system for the vehicle  105 . In one example, the navigation network component  110  determines one or more navigation solutions for the navigation components  115 ,  120 ,  125 , and  130 . In one example, the vehicle  105  comprises one or more sensors  135 ,  140 ,  145 , and  150 . The navigation network component  110  determines one or more navigation parameters, for example, orientation, position, and velocity, for the sensors  135 ,  140 ,  145 , and  150 . In yet another example, the navigation network component  110  determines the navigation solutions for the navigation components  115 ,  120 ,  125 , and  130  and the navigation parameters, for example, orientation, position, and velocity, for the sensors  135 ,  140 ,  145 , and  150 .  
         [0013]     The navigation components  115 ,  120 ,  125 , and  130  in one example comprise one or more inertial sensors, for example, three linear accelerometers and three gyros, to determine navigation parameters (e.g., orientation, position, and velocity) of the sensors  135 ,  140 ,  145  and  150 . In one example, the navigation components  115 ,  120 ,  125 , and  130  comprise one or more Inertial Navigation System (“INS”). In another example, the 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 navigation components  115 ,  120 ,  125 , and  130  in one example comprise varying degrees of accuracy. For example, the navigation components  115  and  120  comprise high performance navigation systems, for example, one nautical mile per hour inertial navigation systems or navigation systems augmented by one or more Global Positioning System (“GPS”) units, and the navigation components  125  and  130  comprise lower performance navigation systems, for example, small tactical accuracy inertial measurement units. The navigation components  115 ,  120 ,  125 , and  130  obtain navigation measurement data for the navigation components  115 ,  120 ,  125 , and  130  and determine navigation parameters (i.e., orientations, positions, and velocities) for the sensors  135 ,  140 ,  145 , and  150 .  
         [0014]     The one or more sensors  135 ,  140 ,  145 , and  150  in one example comprise one or more synthetic aperture radars, one or more optical sensors, or one or more acoustic sensors. In one example, one or more of the sensors  135 ,  140 ,  145 , and  150  are at locations of the navigation components  115 ,  120 ,  125 , and  130 . In another example, one or more of the sensors  135 ,  140 ,  145 , and  150  are at locations distinct from the locations of the navigation components  115 ,  120 ,  125 , and  130 . For example, the sensors  135 ,  140 ,  145 , and  150  are located in between one or more of the navigation components  115 ,  120 ,  125 , and  130 . The navigation system components  152 ,  153 , and  154  in one example comprise one or more embedded GPS-inertial (“EGI”) navigation systems. For example, the navigation system components  152 ,  153 , and  154  comprise one or more LN100s from Northrop Grumman (Northrop Grumman Corporation Corporate Headquarters, 1840 Century Park East, Los Angeles, Calif. 90067-2199, (310) 553-6262; http://www.northropgrumman.com). The external positioning components  155  and  160  comprise a Global Positioning System (“GPS”) receiver and a baro-altimeter. The navigation network processor component  110  and the navigation components  115 ,  120 ,  125 , and  130  comprise an instance of a recordable data storage medium  101 , as described herein.  
         [0015]     The navigation network processor component  110  in one example receives navigation measurement data from the navigation components  115 ,  120 ,  125 , and  130 . The navigation network processor component  110  employs the navigation measurement data from the navigation components  115 ,  120 ,  125 , and  130  to establish a coordinate system, for example, a first coordinate system, for the vehicle  105 . The navigation network processor component  110  establishes a reference location for the vehicle  105  with respect to the coordinate system, for example, the first coordinate system. The navigation network processor component  110  employs the reference location for the vehicle  105  to determine one or more navigation solutions for the navigation components  115 ,  120 ,  125 , and  130 , and/or one or more navigational parameters (i.e., orientations, positions, and velocities) for the sensors  135 ,  140 ,  145 , and  150 , as will be appreciated by those skilled in the art. The navigation network processor component  110  determines the navigational parameters (i.e., orientations, positions, and velocities) for the sensors  135 ,  140 ,  145 , and  150  with respect to the coordinate system established by the navigation network processor component  110 , for example, the first coordinate system. The navigation network processor component  110  provides translated navigation parameters of the sensors  135 ,  140 ,  145 , and  150  in the coordinate system established by the navigation network processor component  110  as illustrated by the outputs  182 ,  184 ,  186 , and  188 . The navigation network processor component  110  provides orientation of the coordinate system established by the navigation network processor component  110  as output  190 .  
         [0016]     The navigation network processor component  110  determines the navigation solutions for the navigation components  115 ,  120 ,  125 , and  130  with respect to the coordinate system established by the navigation network processor component  110 , for example, the first coordinate system. The navigation network processor component  110  sends as outputs  192 ,  194 ,  196 , and  198 , one or more navigation solutions for the navigation components  115 ,  120 ,  125 , and  130  with respect to the coordinate system established by the navigation network processor component  110 . The navigation solutions for the navigation components  115 ,  120 ,  125 , and  130  comprise one or more standard navigation solutions and one or more replacement navigation solutions, as described herein.  
         [0017]     The navigation network processor component  110  employs one or more navigation 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 navigation network processor component  110  employs one or more inertial sensors to determine inertial measurement data for the vehicle  105 . In another example, the navigation network processor component  110  employs one or more pressure altitude sensors to determine pressure altitude measurement data for the vehicle  105 . In yet another example, the navigation network processor component  110  employs one or more GPS units to determine GPS measurements for the vehicle  105 . In yet another example, the navigation network processor component  110  employs one or more air speed sensors to determine air speed measurements for the vehicle  105 . The navigation network processor 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.  
         [0018]     The navigation network processor 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 navigation network processor 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 navigation network processor component  110  employs navigation measurement data from the 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 navigation network processor component  110  employs the navigation measurement data from the navigation components  115 ,  120 ,  125 , and  130  to further refine the coordinate system established by the navigation network processor component  110  for the vehicle  105 . The navigation network processor 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.  
         [0019]     The navigation network processor component  110  communicates with the 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 navigation network processor component  110 . The navigation network processor 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 navigation components  115 ,  120 ,  125 , and  130 . The navigation network processor 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 navigation components  115 ,  120 ,  125 , and  130 . The navigation network processor component  110  corrects the navigation measurement data of the navigation components  115 ,  120 ,  125 , and  130  based on the estimations of the one or more errors. The navigation network processor component  110  provides the corrected navigation measurement data to the navigation components  115 ,  120 ,  125 , and  130 , as illustrated by outputs  165 ,  170 ,  175 , and  180 . The 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 navigation network processor component  110  translates the navigation measurement data of the navigation components  115 ,  120 ,  125 , and  130  from coordinate systems established by the navigation components  115 ,  120 ,  125 , and  130 , for example, one or more second coordinate systems, to the coordinate system established by the navigation network processor component  110 , for example, the first coordinate system, as will be appreciated by those skilled in the art. The navigation network processor component  110  provides navigational parameters for the navigation network processor component  110  as output  182 . The navigation network processor component  110  provides translated navigation parameters for the sensors  135 ,  140 ,  145 , and  150  in the coordinate system established by the navigation network processor component  110  as illustrated by the outputs  182 ,  184 ,  186 , and  188 . The navigation network processor component  110  provides the orientation of the coordinate reference system as output  190 .  
         [0021]     The navigation network processor component  110  estimates one or more lever arms (i.e. parameters used to model three dimensional distance vectors) between a reference location established by the navigation network processor component  110  and the navigation component  115 , the reference location established by the navigation network processor component  110  and the navigation component  120 , the reference location established by the navigation network processor component  110  and the navigation component  125 , and the reference location established by the navigation network processor component  110  and the navigation component  130 . The 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 navigation network processor component  110 .  
         [0022]     The navigation network processor component  110  receives navigation measurement data as a function of time from the navigation components  115 ,  120 ,  125 , and  130 , the navigation systems  152 ,  153 , and  154 , and the external positioning components  155  and  160 . The navigation network processor component  110  establishes a time base for the navigation measurement data. The navigation network processor component  110  synchronizes the navigation measurement data with the time base, as will be appreciated by those skilled in the art. In one example, the navigation component  115  provides a timestamp along with navigation measurement data for the navigation component  115 . The navigation network processor component  110  adjusts the navigation measurement data for the navigation component  115  to the time base of the navigation network processor component  110 . For example, the navigation network processor component  110  compares the timestamp from the navigation component  115  to the time base of the navigation network processor component  110 . The navigation network processor component  110  in one example employs data interpolation and/or data extrapolation to adjust the navigation measurement data to the appropriate time. In another example, the navigation network processor component  110  and the navigation components  115 ,  120 ,  125 , and  130 , the navigation systems  152 ,  153 , and  154 , and the external positioning components  155  and  160 , operate on a synchronized clock, for example, a clock  162 . In yet another example, the navigation network processor component  110  and the navigation components  115 ,  120 ,  125 , and  130 , the navigation systems  152 ,  153 , and  154 , and the external positioning components  155  and  160 , employ timing pulses to synchronize their respective navigation measurement data to the time base of the navigation network processor component  110 .  
         [0023]     The 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 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 navigation components  115 ,  120 ,  125 , and  130  communicate with the navigation network processor component  110  to provide the navigation measurement data of the navigation components  115 ,  120 ,  125 , and  130  to the navigation network processor component  110 . The navigation components  115 ,  120 ,  125 , and  130  receive as input, corrected navigation measurement data of the navigation components  115 ,  120 ,  125 , and  130  from the navigation network processor component  110  (e.g., the outputs  165 ,  170 ,  175 , and  180 ). The navigation components  115 ,  120 ,  125 , and  130  employ the corrected navigation measurement data of the 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 navigation network processor component  110 . For example, the navigation component  115  employs the corrected navigation measurement data of the navigation component  115  to determine motion of the sensor  135  relative to the coordinate system established by the navigation network processor component  110 .  
         [0024]     Turning to  FIG. 2 , the navigation network processor component  110  comprises one or more reference coordinate components  205 , one or more health monitor components  210 , one or more standard navigation solution components  215 , one or more replacement navigation solution components  220 , and one or more flexural model components  225 . The reference coordinate component  205  in one example establishes a coordinate system for the vehicle  105 . The health monitor component  210  in one example identifies failing navigation components from navigation measurement data obtained from the navigation components  115 ,  120 ,  125 , and  130 , as will be described herein. The standard navigation solution component  215  in one example determines navigation solutions for the navigation components  115 ,  120 ,  125 , and  130 . The replacement navigation solution component  220  in one example determines replacement navigation solutions for the navigation components  115 ,  120 ,  125 , and  130 . The flexural model component  225  determines one or more dynamic lever arms for one or more of the navigation components  115 ,  120 ,  125 , and  130 .  
         [0025]     The standard navigation solution component  215  provides as outputs  260 ,  261 ,  262 , and  263 , one or more valid navigation solutions for one or more of the navigation components  115 ,  120 ,  125 , and  130 . The standard navigation solution component  215  provides the outputs  260 ,  261 ,  262 , and  263  to the replacement navigation solution component  220 . The replacement navigation solution component  220  provides as outputs  265 ,  266 ,  267 , and  268 , one or more replacement navigation solutions for one or more of the navigation components  115 ,  120 ,  125 , and  130 . The flexural model component  225  provides as output  259 , the one or more dynamic lever arms for the one or more of the navigation components  115 ,  120 ,  125 , and  130  to the replacement navigation solution component  220 .  
         [0026]     The reference coordinate component  205  takes as input, outputs  230 ,  235 ,  240 , and  245  from the navigation components  115 ,  120 ,  125 , and  130 , respectively. The outputs  230 ,  235 ,  240 , and  245  in one example comprise one or more physical parameters, for example, accelerations, angular rates, and temperatures. The reference coordinate component  205  provides orientation information for the vehicle  105  to the standard navigation solution component  215  as output  250 . The health monitor component  210  takes as input, the outputs  230 ,  235 ,  240 , and  245 . The health monitor component  210  makes one or more comparisons of the outputs  230 ,  235 ,  240 , and  245  of the navigation components  115 ,  120 ,  125 , and  130  to one or more nominal outputs for the navigation components  115 ,  120 ,  125 , and  130 . The health monitor component  210  provides navigation component health indicators to the standard navigation solution component  215  and the replacement navigation solution component  220  based on the one or more comparisons for the navigation components  115 ,  120 ,  125 , and  130 , as outputs  252  and  254 , respectively.  
         [0027]     The health monitor component  210  in one example determines one or more health indicators for the navigation component  115 ,  120 ,  125 , and  130 . The health monitor component  210  in one example comprises one or more navigation solution determination components  275  and one or more expected values components  280 . The navigation solution determination component  275  in one example generates one or more relationships for the navigation components  115 ,  120 ,  125 , and  130  that describe behavior of a navigation component as a function of time with respect to the navigation components  115 ,  120 ,  125 , and  130 . In one example, the navigation solution determination component  275  generates a relationship for the navigation component  115  as a function of time with respect to the navigation components  120  and  125 . For example, the navigation solution determination component  275  generates one or more equations as functions of time for the navigation component  115  in terms of the navigation components  120  and  125 . In another example, the navigation solution determination component  275  generates a relationship for the navigation component  120  as a function of time with respect to the navigation components  115  and  130 . For example, the navigation solution determination component  275  generates one or more equations as functions of time for the navigation component  120  in terms of the navigation components  115  and  130 .  
         [0028]     The expected values component  280  provides one or more expected values for the outputs  230 ,  235 ,  240 , and  245  of the navigation components  115 ,  120 ,  125 , and  130 . For example, the outputs  230 ,  235 ,  240 , and  245  comprise position, velocity, estimations of accelerometer or gyroscope drift errors, and magnitudes of sensed acceleration or angular rates, as will be appreciated by those skilled in the art. In one example, the expected values component  280  employs the one or more equations generated by the navigation solution determination component  275  and the lever arms  259  computed by the flexural model component  225  to determine the expected values for the outputs  230 ,  235 ,  240 , and  245  of the navigation components  115 ,  120 ,  125 , and  130 . In another example, the expected values component  280  is pre-programmed with the expected values as a function of time for the outputs  230 ,  235 ,  240 , and  245  of the navigation components  115 ,  120 ,  125 , and  130 .  
         [0029]     In one example, the health monitor component  210  employs an Autonomous Integrity Monitored Extrapolation (“AIME”) technique to generate the one or more health indicators for the navigation components  115 ,  120 ,  125 , and  130 . The health monitor component  210  sends as output  252 , the health indicators to the standard navigation solution component  215 . The health monitor component  210  sends as output  254 , the health indicators to the replacement navigation solution component  220 . In another example, the health monitor component  210  determines one or more differences between the values obtained from the outputs  230 ,  235 ,  240 , and  245  with one or more expected values for the outputs  230 ,  235 ,  240 , and  245 . In yet another example, the health monitor component  210  quantifies the differences and sends the quantified differences to standard navigation solution component  215  and the replacement navigation solution component  220 . In yet another example, the health monitor component  210  compares the differences to threshold values for the values of the outputs. The health monitor component  210  provides a health indicator based on the comparison of the difference to the threshold values. The health monitor component  210  sends as output  258 , one or more indications of the health of the navigation component outputs  230 ,  235 ,  240 , and  245  to the flexural model component  225 . The flexural model component  225  employs the health indicators to determine which of the navigation component outputs  230 ,  235 ,  240 , and/or  245  may be reliably used to compute a flexural model.  
         [0030]     The flexural model component  225  in one example develops a model describing the reaction of the vehicle  105  in motion. The model in one example describes the displacement of the navigation components  115 ,  120 ,  125 , and/or  130  relative to one another. The flexural model component  225  employs one or more rules, for example, one or more rules pertaining to lever arms, compliances, or resonance of the vehicle  105 , and mechanics of the vehicle  105 , to develop the model describing the reaction of the vehicle  105  in motion. The flexural model component  225  in one example estimates one or more lever arm parameters that describe three dimensional dynamic displacement vectors between the navigation components  115 ,  120 ,  125 , and  130  and a reference location established by the navigation network processor component  110 . The flexural model component  225  in one example receives as inputs, the outputs  230 ,  235 ,  240 , and  245  (e.g., physical parameters, for example, acceleration, angular rates, and temperatures). The flexural model component  225  employs the outputs  230 ,  235 ,  240 , and  245  to perform one or more estimations of forces, torques, deflections, and displacements of the navigation components  115 ,  120 ,  125 , and  130  of the vehicle  105 . The flexural model component  225  employs the one or more estimations to determine behaviors for dynamic lever arms of the navigation components  115 ,  120 ,  125 , and  130 .  
         [0031]     The flexural model component  225  in one example receives as inputs, the outputs  260 ,  261 ,  262 , and  263  from the standard navigation solution component  215 . The outputs  260 ,  261 ,  262 , and  263  in one example comprise navigation solutions and/or navigation measurement data. The flexural model component  225  in one example performs one or more comparisons of the flexural model to the navigation solutions  260 ,  261 ,  262 , and  263  to provide further refinement of the flexural model. In one example, the flexural model component  225  comprises a deterministic mechanical model. In another example, the flexural model component  225  comprises a flexible adaptive form, for example, a neural network.  
         [0032]     The flexural model component  225  receives as input, output  258  from the health monitor component  210 . The flexural model component  225  employs the output  258  to determine which of the navigation component outputs  230 ,  235 ,  240 , and/or  245  and which of the standard navigation solutions  260 ,  261 ,  262 , and/or  263  are reliable enough to employ in calculating or updating the flexural model. The flexural model component  225  provides as the output  259 , the one or more dynamic lever arms for the one or more of the navigation components  115 ,  120 ,  125 , and  130  to the replacement navigation solution component  220 . The replacement navigation solution component  220  employs the output  259  and the outputs  260 ,  261 ,  262 , and  263  to estimate the navigation solutions for unhealthy navigation components, for example, the navigation component  120 .  
         [0033]     The replacement navigation solution component  220  in one example takes as input, the outputs  254 ,  259 ,  260 ,  261 ,  262 , and  263 . The replacement navigation solution component  220  produces one or more replacement solutions  265 ,  266 ,  267 , and  268  for one or more of the navigation components  115 ,  120 ,  125 , and  130 . The replacement navigation solution component  220  in one example monitors the outputs  230 ,  235 ,  240 , and  245  of the navigation components  115 ,  120 ,  125 , and  130 . The replacement navigation solution component  220  learns to simulate an output of a navigation component based upon the outputs of the remaining navigation components. The replacement navigation solution component  220  develops one or more relationships between the outputs  230 ,  235 ,  240 , and  245  the describe the behavior of the outputs  230 ,  235 ,  240 , and  245  with respect to one or more of the outputs  230 ,  235 ,  240 , and  245 . For example, the replacement navigation solution component  220  comprises one or more neural networks that monitor the outputs  230 ,  235 ,  240 , and  245 . The replacement navigation solution component  220  monitors the outputs  230 ,  235 ,  240 , and  245  to develop one or more relationships that describe the behavior of the output  230  with respect to the outputs  235 ,  240 , and/or  245 . The replacement navigation solution component  220  employs the one or more relationships to simulate the output  230  of the navigation component  115 . As the replacement navigation solution component  220  develops the one or more relationships, the replacement navigation solution component  220  verifies the one or more relationships by comparing a value obtained by use of the one or more relationships with values of the outputs  230 ,  235 ,  240 , and  245  from the navigation components  115 ,  120 ,  125 , and  130 .  
         [0034]     For example, the replacement navigation solution component  220  simulates the output  230  of the navigation component  115 . The replacement navigation solution component  220  monitors the outputs  235 ,  240 , and  245  over time. The replacement navigation solution component  220  constructs one or more equations, or systems of equations, as a function of time from the outputs  235 ,  240 , and  245  that describes the behavior of the output  230  in terms of the outputs  235 ,  240 , and  245 , as a function of time. The replacement navigation solution component  220  performs a comparison of a value obtained from the output  230  at a time period, for example, a current value for the output  230 , with a value obtained from the one or more equations at that time period. The replacement navigation solution component  220  adjusts the one or more equations that describe the output  230  in terms of the outputs  235 ,  240 , and  245  based upon the comparison, as will be appreciated by those skilled in the art.  
         [0035]     Through employment of one or more relationships that describe the behavior of the navigation components  115 ,  120 ,  125 , and  130  in terms of the navigation components  115 ,  120 ,  125 , and  130 , the replacement navigation solution component  220  provides redundant navigation solutions for the outputs  230 ,  235 ,  240 , and  245 , upon failure of one or more of the navigation components  115 ,  120 ,  125 , and  130 . For example, upon failure of the navigation component  115 , the replacement navigation solution component  220  employs the one or more relationships for the output  230  to construct a value for the output  230  with reasonable accuracy.  
         [0036]     Turning to  FIG. 3 , the standard navigation solution component  215  in one example comprises one or more rigid lever arm model components  310  and  340 , one or more summing nodes  318  and  348 , one or more flexural model components  320 , and one or more filters  325 . The rigid lever arm model component  310  comprises a base-line static position for the navigation component  115 . The rigid lever arm model component  310  determines a base-line static lever arm for the navigation component  115  based on the base-line static position. The base-line static lever arm for the navigation component  115  comprises a three-dimensional position distance, or vector, between a reference location established by the navigation network processor component  110  and the navigation component  115 . The rigid lever arm model component  310  cooperates with the reference coordinate component  205  to project the base-line static lever arm for the navigation component  115  in the coordinate system established by the reference coordinate component  205  to determine a static lever arm for the navigation component  115 . The rigid lever arm model component  310  sends the static lever arm for the navigation component  115  as output  316  to a summing node  318 .  
         [0037]     The navigation component  115  determines navigation measurement data for the navigation component  115  in reference to a coordinate system established by the navigation component  115 , for example, a second coordinate system. The navigation component  115  sends as output  230 , the navigation measurement data for the navigation component  115  in reference to the coordinate system established by the 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  230  from the navigation component  115  to produce as output  260 , navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205 , for example, the first coordinate system.  
         [0038]     The output  260  comprising the navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  305  is enhanced through employment of a flexural model component  320 . The flexural model component  320  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 navigation components  115 ,  120 ,  125 , and  130 , the flexural model component  320  expresses the relative displacement of any point along the structure of the vehicle. For example, the flexural model component  320  takes as input one or more lever arm parameters of the distances between a reference location established by the navigation network processor component  110  and each of the navigation components  115 ,  120 ,  125 , and  130  as a function of time. The flexural model component  320  comprises one or more equations describing the reaction of the vehicle  105  during motion. For example, the flexural model component  320  comprises equations describing the bending of the structure of the vehicle  105  as a function of time. The flexural model component  320  applies lever arm parameters 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  320  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  320  employs one or more neural networks that cooperate to develop a model describing the displacement of the sensors  135 ,  140 ,  145 , and  150  relative to one another. The flexural model component  320  provides as output  324 , equations describing the relative displacement of the sensor  135  along the structure of the vehicle  105  as a function of time.  
         [0039]     For example, the flexural model component  320  comprises one or more incremental dynamic lever arm correction components. The incremental dynamic lever arm correction components comprise models describing reactions of the vehicle  105  during motion. The incremental dynamic lever arm correction components employ the models to provide positions for the navigation components  115 ,  120 ,  125 , and  130  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 navigation component  115 . As the vehicle  105  bends, the lever arm between the master navigation component  110  and the navigation component  115  changes.  
         [0040]     In one example, the flexural model component  320  in one example takes as input, output  326  from the reference coordinate component and output  328  from the navigation component  115 . The incremental dynamic lever arm correction components in one example employ the outputs  326  and  328  to determine a dynamic lever arm for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205 . The incremental dynamic lever arm correction components send the dynamic lever arm for the navigation component  115  to the summing node  318 . The summing node  318  combines the outputs  316 ,  230 , and  324  to produce the output  260 . Thus, the summing node  318  generates the output  260  as comprising more accurate navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205  for the vehicle  105  in motion. The output  324  of the incremental dynamic lever arm correction components obtains more accuracy through employment of the filter  325 , for example, a Kalman filter, as will be discussed herein.  
         [0041]     The filter  325  receives as input, the output  260  from the summing node  318 . The filter  330  compares the output  260  for a given timestamp (i.e., the navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205 ) with the navigation measurement data from the reference coordinate component  205  at the given timestamp. The filter  325  estimates errors in the output  260 . The filter  325  provides as output  332 , corrected navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205 . The 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  205 . The navigation component  115  employs the output  332  to adjust the coordinate system established by the navigation component  115 . In addition, the filter  325  sends as output  334 , the corrected navigation measurement data for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205  to the flexural model component  320 . The flexural model component  320  employs the output  334  to correct the output  324 , the dynamic lever arm for the navigation component  115 . Thus, the flexural model component  320 , the navigation component  115 , and the filter  325  cooperate to iteratively align a coordinate system of the navigation component  115  with the coordinate system established by the reference coordinate component  205 .  
         [0042]     The navigation component  120 , the sensor  140 , the reference coordinate component  205 , rigid lever arm model component  340 , summing node  348 , the flexural model component  320 , and outputs  235 ,  346 ,  261 ,  354 ,  358 ,  362 , and  364 , interact in a similar fashion to the navigation component  115 , the sensor  135 , the reference coordinate component  205 , the rigid lever arm model component  310 , the summing node  318 , the flexural model component  320 , and the outputs  230 ,  316 ,  260 ,  324 ,  328 ,  332 , and  334 . The reference coordinate component  205 , the rigid lever arm model components  310  and  340 , the flexural model components  320 , and the filter  325 , comprise one or more instances of a recordable data storage medium  101 , as described herein.  
         [0043]     Referring still to  FIG. 3 , the navigation component  115  sends as output  328 , the navigation measurement data for the navigation component  115  to the flexural model component  320 . The flexural model component  320  employs the output  328  to provide increased accuracy of the dynamic lever arm for the navigation component  120  in reference to the coordinate system established by the reference coordinate component  205 . The navigation component  120  sends as output  358 , the navigation measurement data for the navigation component  120  to the flexural model component  320 . The flexural model component  320  employs the output  358  to provide increased accuracy of the dynamic lever arm for the navigation component  115  in reference to the coordinate system established by the reference coordinate component  205 .  
         [0044]     The filter  325  receives as input, navigation measurement data from the reference coordinate component  205 , and the navigation components  115  and  120 . The filter  325  receives as input, output  370  from the reference coordinate component  205 , the output  260  from the navigation component  115 , and the output  261  from the navigation component  120 . The filter  325  estimates errors in navigation measurement data received from the reference coordinate component  205 , and the navigation components  115  and  120 . The filter  325  corrects the errors and sends as output  372 , the corrected navigation measurement data with respect to the coordinate system established by the reference coordinate component  205  to the reference coordinate component  205 . The reference coordinate component  205  employs the output  372  to adjust a coordinate system established by the reference coordinate component  205 . For example, the reference coordinate component  205  employs the output  372  to adjust a base-line coordinate system established by the reference coordinate component  205 . The filter  325  and the reference coordinate component  205  cooperate to align the coordinate system established by the reference coordinate component  205  and the coordinate system established by the filter  325 . The filter  325  sends as the outputs  332 ,  334 ,  362 , and  364 , the corrected navigation measurement data with respect to the coordinate system established by the reference coordinate component  205  to the reference coordinate component  205 , the navigation components  115  and  120 , and the flexural model component  320 .  
         [0045]     An illustrative description of exemplary operation of the apparatus  100  is presented, for explanatory purposes.  
         [0046]     Turning to  FIGS. 2-4 , in STEP  405 , the navigation network processor component  110  determines a navigation solution as a function of time for the vehicle  105 . In STEP  410 , the reference coordinate component  205  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  415 , the reference coordinate component  205  receives navigation measurement data with respect to a coordinate system established by the navigation component  115 , for example, a second coordinate system, and time-tag from the navigation component  115  for the sensor  135 . The reference coordinate component  205  employs the time-tag to determine the navigation measurement data of the reference coordinate component  205  at a time described by the time-tag. In STEP  420 , the reference coordinate component  205  compares the navigation measurement data of the navigation component  115  at the time described by the time-tag to the navigation measurement data of the reference coordinate component  205  at the time described by the time-tag. The navigation measurement data of the reference coordinate component  205  at the time described by the time-tag in one example comprises navigation measurement data of the reference coordinate component  205  adjusted by one or more lever arms between the reference coordinate component  205  and the navigation components  115 ,  120 ,  125 , and  130 , as described herein.  
         [0047]     In STEP  425 , the reference coordinate component  205  and the filter  325  estimate errors in the navigation measurement data from the navigation component  115 . In STEP  430 , the filter  325  corrects the errors in the navigation measurement data from the navigation component  115 . In STEP  435 , the filter  325  translates the corrected navigation measurement data for the navigation component  115  from the coordinate system established by the navigation component  115 , (e.g., the second coordinate system) to the coordinate system established by the reference coordinate component  205  (e.g., the first coordinate system). In STEP  440 , the summing node  318  employs the corrected and translated navigation measurement data for the 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 reference coordinate component  205  of the navigation network processor component  110 .  
         [0048]     Turning to  FIG. 5 , in STEP  505 , the health monitor component  210  obtains navigation measurement data of the output  230  from the navigation component  115 . In STEP  510 , the health monitor component  210  determines a difference between the navigation measurement data of the output  230  and expected navigation measurement data of the output  230 . For example, the difference between the orientation of the navigation component  115  and the expected orientation of the navigation component  115  is three degrees. In STEP  515 , the health monitor component  210  quantifies the difference based upon a percentage of the difference. For example, the difference of three degrees is within a tolerance limit for the navigation component  115 . In STEP  520 , the health monitor component  210  determines the health indicator for the navigation component  115  based on the quantified difference. The health monitor component  210  provides a ninety-eight percent health indicator for the navigation component  115 .  
         [0049]     Turning to  FIGS. 1, 2 , and  6 , the navigation network component  110  determines navigation solutions for the navigation components  115  and  120 . In STEP  605 , the navigation network component  110  receives navigation measurement data from the navigation components  115  and  120 . In STEP  610 , the health monitor component  210  determines that the navigation component  115  is healthy and that the navigation component  120  is unhealthy. In STEP  615 , the standard navigation solution component  215  determines a navigation solution for the navigation component  115 . In STEP  620 , the standard navigation solution component  215  provides the navigation solution for the navigation component  115  as output  260 . In STEP  625 , the flexural model component  225  obtains physical parameters measured by the healthy navigation component, for example, the navigation component  115 . In STEP  630 , the replacement navigation solution component  220  obtains a dynamic lever arm for the unhealthy navigation component, for example, the navigation component  220 , from the flexural model component  225 . In STEP  635 , the replacement navigation solution component  220  determines the replacement navigation solution for the navigation component  220  based on a relationship between the navigation component  115  (i.e., the healthy navigation component) and the navigation component  120  (i.e., the unhealthy navigation component), the navigation solution for the navigation component  115 , the physical parameters for the navigation component  120 , and the dynamic lever arm for the navigation component  120 . The replacement navigation solution component  220  provides the replacement navigation solution as output  265 .  
         [0050]     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.  
         [0051]     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 navigation network processor component  110 , the navigation components  115 ,  120 ,  125 , and  130 , the flexural model component  225 , the reference coordinate component  205 , the rigid lever arm model components  310  and  340 , and the filter  320 . 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.  
         [0052]     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.  
         [0053]     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.