Abstract:
A dynamic miscompare module indicates instrumentation datum reliability by comparing a calculated difference between received instrumentation data and a total of a measured change in the received instrumentation data and a threshold value. The comparison varies dynamically with the measured change in the received instrumentation data. In an event the calculated difference exceeds the total, there is a miscompare condition and the related instrumentation datum is unreliable. The dynamic miscompare module alerts an operator of the condition by indicating a miscompare message indicator. The indicator is formed from a miscompare cue and a miscompare descriptor. The dynamic miscompare module further indicates the condition by interposing a leader between the miscompare message indicator and the unreliable instrumentation datum. Alternatively, the dynamic miscompare module locates the miscompare message indicator proximal to the unreliable instrumentation datum. Such telling and informative indication enables the operator to react to the miscompare condition effectively and accurately.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/711,973 filed on Aug. 26, 2005, the entire teachings of which are herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     In the field of avionics, the technique of comparing two or more sets of data from similar or identical data sensors is employed to determine the reliability of an instrumentation datum. For example, data from two or more engine indicating systems (EIS), data from two or more attitude heading systems (AHS), or data from two or more air data systems (ADS) are inputted into a Primary Flight Display (PFD). Comparators inside the PFD compare datum from one system against datum from another like system, e.g., EIS 1  versus EIS 2 . A significant difference between like systems indicates instrumentation datum from at least one system is erroneous and cannot be relied upon. A “miscompare” condition is said to have arisen.  
         [0003]     An operator (e.g., a pilot) is alerted of a miscompare condition by the PFD. The operator may then interrogate other instrumentation data to evaluate the reasonableness of the suspect instrumentation datum. Should the operator determine that the suspect instrument datum is unreliable; the operator may then deselect or otherwise exclude that datum from the PFD.  
         [0004]     The operator may be alerted to a miscompare condition in various ways. For example, an ‘ATT’ indicator is normally displayed on a PFD in the absence of a  
         [0005]     The operator may be alerted to a miscompare condition in various ways. For example, an ‘ATT’ indicator is normally displayed on a PFD in the absence of a miscompare condition, i.e., there is no significant difference between attitude data. If however, pitch data (one measure of attitude) varies by X degrees, where the absolute value of X is greater than a set threshold value, then a miscompare warning indicator ‘PIT’ may be displayed in yellow, replacing the ‘ATT’ indicator. Additionally, if roll data (another measure of attitude) varies by Y degrees, where the absolute value of Y is greater than a set threshold value, then a miscompare warning indicator ‘ROL’ may be displayed in yellow, replacing the ‘ATT’ indicator.  
         [0006]     A third possible miscompare condition exists. If both pitch data and roll data vary by X and Y degrees, where the absolute values of X and Y are greater than their respective thresholds, then an indicator ‘ATT’ may be displayed in yellow to indicate a miscompare condition. In summary, the operator is alerted to a miscompare condition when the PFD no longer indicates ‘ATT’ and either indicates ‘PIT’, ‘ROL’ or ‘ATT’ in yellow.  
       SUMMARY OF THE INVENTION  
       [0007]     Previous methods for evaluating reliability of an instrumentation datum require an operator (e.g., a pilot) to first determine whether there is a difference between data provided by two or more similar or like systems. That is, the operator must first determine whether a miscompare condition exists before the operator can evaluate the reliability of the instrumentation datum.  
         [0008]     Using the example provided in the previous section, the color yellow indicates that a miscompare condition exists. While the operator is alerted to the miscompare condition, the operator does not know which instrumentation datum raised the miscompare condition, i.e., the operator does not known which instrumentation datum cannot be relied upon. Further deciphering by the operator is required to determine which instrumentation datum cannot be relied upon.  
         [0009]     Again using the pervious example, the operator must know that a yellow ‘PIT’ indicator indicates a miscompare in pitch data while a yellow ‘ROL’ indicator indicates a miscompare in roll data. Furthermore, the operator must know that a yellow ‘ATT’ indicator signifies a miscompare in both pitch and roll data. Consequently, the operator is tasked with deciphering an indicator to ascertain the reliability of an instrumentation datum.  
         [0010]     Ordinarily, an operator may carry out the task of deciphering such an indicator as a matter of routine or even as a reflex. However, when faced with a myriad of indicators and instrumentation data, all provided concurrently on a PFD, the operator may be overwhelmed and unable to decipher an each indicator effectively. The operator&#39;s ability to decipher an indicator may be further limited when multiple miscompare conditions arise. Consequently, the operator&#39;s ability to react to a miscompare condition effectively is compromised.  
         [0011]     Contrastingly, a dynamic miscompare module in accordance with the principles of the present invention, alerts an operator to a miscompare condition in a more discernable, ascertainable, and comprehendible manner than previously available.  
         [0012]     A method and an apparatus for indicating instrumentation datum reliability is provided. A method according to an example embodiment of the present invention includes: i) receiving a plurality of instrumentation data, ii) calculating a difference in the received plurality of instrumentation data, iii) measuring over time a change in the received plurality of instrumentation data, iv) comparing the calculated difference with a total of the measured change and a threshold value, v) and indicating a miscompare message indicator when the calculated difference exceeds the total of the measured change and the threshold value, the indicated miscompare message indicator providing an indication of reliability of an instrumentation datum.  
         [0013]     A leader may be interposed between the indicated miscompare message indicator and the instrumentation datum. Alternatively, the indicated miscompare message indicator may be located proximally to the instrumentation datum.  
         [0014]     Interposing a leader between a miscompare message indicator and an instrumentation datum allows an operator to readily discern, ascertain, and comprehend which instrumentation datum is unreliable. Similarly, locating a miscompare message indicator proximally to an instrumentation datum allows an operator to readily discern, ascertain, and comprehend which instrumentation datum is unreliable.  
         [0015]     The indicated miscompare message indicator may be formed by a miscompare cue and a miscompare descriptor. The miscompare cue may be shaped as a rectangle, a square, an ellipse, a circle, a triangle or a polygon. Alternatively, the miscompare cue may be shaped as a callout balloon. The miscompare descriptor may be printed as English text, non-English text, an alphanumerical character string or a combination thereof.  
         [0016]     Forming an indicated miscompare message indicator as a miscompare cue and a miscompare descriptor allows an operator to readily discern, ascertain, and comprehend which instrumentation datum is unreliable. For example, shaping the miscompare cue as a rectangle alerts an operator of a miscompare condition visually. As another example, printing the miscompare descriptor as English text alerts an operator of a miscompare condition textually.  
         [0017]     In another embodiment of the present invention, a method for indicating instrumentation datum reliability includes: i) receiving a first instrumentation datum and at least one second instrumentation datum, ii) calculating a difference between the first instrumentation datum and at least one second instrumentation datum to determine a calculated difference, iii) measuring over time a change in the first instrumentation datum and at least one second instrumentation datum to determine a measured changed, iv) comparing the calculated difference with a total of the measured change and a threshold value, v) and indicating a miscompare message indicator to indicate the reliability of an instrumentation datum in an event the calculated difference exceeds the total of the measured change and the threshold value. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.  
         [0019]      FIG. 1A  is a screen view of a flight display in accordance with one embodiment of the present invention;  
         [0020]      FIG. 1B  is a screen view of a flight display in accordance with one embodiment of the present invention;  
         [0021]      FIG. 2  is a block diagram of an exemplary Primary Flight Display system (PFD) including an exemplary dynamic miscompare module in accordance with one embodiment of the present invention;  
         [0022]      FIG. 3  is a flowchart of a dynamic miscompare module in accordance with one embodiment of the present invention;  
         [0023]      FIG. 4  is an illustration of miscompare message indicator; and  
         [0024]      FIG. 5  is a block diagram of an exemplary dynamic miscompare module in accordance with one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     A description of preferred embodiments of the invention follows.  
         [0026]     When operating a vehicle, an operator depends on the reliability of the instrumentation data presented. For example, when flying an aircraft, a pilot or a copilot may use instrumentation data as shown in  FIGS. 1A and 1B  to a fly the aircraft. An exemplary Primary Flight Display (PFD) system  100  presents or otherwise indicates an airspeed datum  105 , a localized datum  110 , a roll/pitch datum  115 , a glideslope datum  120 , an altitude datum  125  and a heading datum  130 . Additionally, the PFD  100  may also present or otherwise indicate an airspeed miscompare message indicator  105   a,  a localized miscompare message indicator  110   a,  a roll/pitch miscompare message indicator  115   a,  a glideslope miscompare message indicator  120   a,  an altitude miscompare message indicator  125   a,  and a heading miscompare message indicator  130   a,  in addition to the aforementioned instrumentation data.  
         [0027]     A miscompare message indicator (e.g.,  105   a,    110   a,    115   a,    120   a,    125   a,  or  130   a ) alerts the operator that instrumentation datum (e.g.,  105 ,  110 ,  115 ,  120 ,  125 , or  130 ) is not reliable and that the operator should exercise caution when relying on such instrumentation datum. For example, if the airspeed miscompare message indicator  105   a  is indicated in conjunction with the airspeed datum  105 , the operator is alerted that the airspeed datum  105  cannot be relied upon. Conversely, if the airspeed miscompare message indicator  105   a  is not indicated in conjunction with the airspeed datum  105  (i.e., PFD system  100  only displays the airspeed datum  105 ) the operator may rely on the airspeed datum  105 .  
         [0028]     The miscompare message indicators (e.g.,  105   a,    110   a,    115   a,    120   a,  and  130   a ) may be an alphanumerical character string, English text, non-English text or a combination thereof. Additionally, the miscompare message indicators (e.g.,  105   a,    110   a,    115   a,    120   a,  and  130   a ) may further include symbols and graphics known in the art.  
         [0029]     While it is disclosed that the miscompare message indicators (e.g.,  105   a,    110   a,    115   a,    120   a,  and  130   a ) are presented by the exemplary PFD  100 , one skilled in the art will readily recognize the presentation of a miscompare message indicator is not limited to a PFD, such as the PFD  100 . For example, the principles of present invention may also be applied to a Multi-Function Display (MFD) system and other such systems as known in the art.  
         [0030]     Furthermore, while it is disclosed that the miscompare message indicators (e.g.,  105   a,    110   a,    115   a,    120   a,  and  130   a ) are presented by the exemplary PFD  100 , one skilled in the art will readily recognize the presentation of a miscompare message indicator is not limited to a single PFD, such as the PFD  100 . The principles of present invention may also be applied to more than one PFD. For example, a cockpit may have a first PFD for a pilot and a second PFD for a co-pilot. In this example, a miscompare message indicator presented on the first PFD is also presented on the second PFD, and vice versa.  
         [0031]      FIG. 2  is a block diagram of an exemplary Primary Flight Display (PFD) system  100  which includes an exemplary dynamic miscompare module  230  in accordance with the principles of the present invention. The PFD system  100  includes a Sensor Interface Unit (SIU)  205 , a controller  210 , and a display  215 . The controller  210  further includes a digital processor  220 , a memory  225  and a dynamic miscompare module  230 . The processor  220  loads from the memory  225  the dynamic miscompare module  230 . The processor-memory configuration of  FIG. 2  is only an exemplary illustration, one of ordinary skill in the art will readily appreciate the present invention is not limited to the illustrated processor-memory configuration, but may employ other configurations known in the art. For example, the memory  225  may be “on die,” i.e., the processor  220  and the memory  225  may be integrated onto a single integrated circuit (IC).  
         [0032]     Sensor signals from various sensors  201   a,    201   b  . . .  201   n  (e.g., an airspeed sensor) are collected by a Sensor Interface Unit (SIU)  205 . The SIU  205  in turn provides a plurality of instrumentation data (i.e., at least a first datum and a second datum) to the processor  220 . The processor  220  executes the dynamic miscompare module  230  on the received plurality of instrumentation data. The display  215  then displays or otherwise indicates the output from the dynamic miscompare module  230 .  
         [0033]      FIG. 3  is a flow chart of a dynamic miscompare module  230 . At step  335 , the dynamic miscompare module  230  receives a plurality of instrumentation data from sensors  201   a,    202   b  . . .  201   n  (see  FIG. 2 ). For example, the dynamic miscompare module  230  receives a first indicated airspeed datum from a first airspeed sensor, a second indicated airspeed datum from a second airspeed sensor, and a third indicated airspeed datum from a third airspeed sensor. As such, the received plurality of instrumentation data consists of the first indicated airspeed datum, second indicated airspeed datum, and the third indicated airspeed datum, from the first, second, and third indicated airspeed sensors, respectively.  
         [0034]     In addition to indicated airspeed, the received plurality of instrumentation data also corresponds to other flight parameters such as pitch attitude, roll attitude, magnetic heading, and pressure altitude. One skilled in the art will readily recognize other flight parameters are within the contemplation of the present invention.  
         [0035]     At step  340 , the dynamic miscompare module  230  calculates a difference in the received plurality of instrumentation data. Continuing with the previous example, a first difference in indicated airspeed is calculated from the first indicated airspeed datum and the second indicated airspeed datum. Similarly, a second difference in indicated airspeed is calculated from the second indicated airspeed datum and the third indicated airspeed datum, and so on.  
         [0036]     At step  345 , the dynamic miscompare module  230  measures over time a change in the received plurality of instrumentation data.  
         [0037]     At step  350 , the dynamic miscompare module  230  compares the difference in the received plurality of instrumentation data calculated in step  340  with the measured change in the received plurality of instrumentation data measured in step  345 . If the absolute value of the calculated difference is greater than the total of a threshold value and the product of the measured change and time (or scale factor), then a miscompare message indicator is indicated at step  355 . If, however, the absolute value of the calculated difference is less than the total of a threshold value and the product of the measured change and time, then a miscompare message indicator is not indicated at step  360 .  
         [0038]     The threshold value used in the comparing step  350  may be statically defined or constant. For example, the threshold value is set based on known errors of the instrumentation datum which do not vary based on flight conditions. Alternatively, the threshold value used in the comparing step  350  may be dynamically defined or varied with one or more flight parameters. For example, a threshold value for a pressure altitude datum is 50 feet at altitudes below 5,000 feet, while the threshold value is 150 feet at altitudes above 30,000 feet. As another example, a threshold value for a pressure altitude datum varies linearly from 50 feet to 150 feet for altitudes between 5,000 feet and 30,000 feet. As such, the threshold for the pressure altitude datum varies with the pressure altitude parameter—the greater the pressure altitude, the greater the threshold for the pressure altitude datum.  
         [0039]     The outcome of the comparing step  350  depends not only on a calculated difference in a received plurality of instrumentation data, but also on a measured change in the received plurality of instrumentation data. For example, a miscompare message indicator for a roll attitude datum is not displayed despite a calculated difference in roll attitude data exceeding a threshold value for roll attitude when a measured change in roll attitude data is large. This occurs, for example, when an aircraft is undergoing aggressive maneuvers or otherwise experiencing rapid changes in flight. In this way, the comparing step  350  is dynamic and varies depending on how the aircraft is being flown.  
         [0040]     To further illustrate the comparing step  350  consider the following. When an aircraft is in level flight (i.e., zero degrees to the horizon) the pitch attitude of the aircraft does not change over time. In other words, the change in pitch or the pitch rate of the aircraft is zero degrees per second. Other units of measure such as, but limited to, radians per second may also be used. When the aircraft, however, is in a steep climb or drive as to quickly change altitude, the pitch attitude of the aircraft changes by a large amount over a short period of time. As such, the pitch rate of the aircraft is large when the aircraft is in a steep climb or drive. In contrast, when the aircraft is gradually ascending or descending, as to slowly change altitude, the pitch attitude of the aircraft changes by a small amount over a long period of time. As such, the pitch rate of the aircraft is small when the aircraft is gradually ascending or descending.  
         [0041]     By way of example, the dynamic miscompare module  230  at the comparing step  350  compares whether the absolute difference in pitch attitude data is greater than the sum of 3.0 degrees and the absolute pitch rate multiplied by 0.3 seconds. As an example, assume the aircraft has a pitch rate of 30 degrees per second when the aircraft is in a steep climb and a pitch rate of 3 degrees per second when the aircraft is in a gradual climb. Accordingly, a miscompare message indicator is displayed at step  355  when the absolute difference in pitch data is greater than 12 degrees when the aircraft is in a steep climb. In contrast, when the aircraft is in a gradual climb, a miscompare message indicator is displayed when the absolute difference in pitch data is greater than 3.9 degrees.  
         [0042]     As illustrated by the above example, a greater difference in instrumentation data is acceptable or tolerable when a change in instrumentation data is great. Conversely, a smaller difference in instrumentation data is acceptable or tolerable when a change in instrumentation data is small. As such, under certain circumstances a miscompare condition arises while in other circumstances a miscompare condition does not arises.  
         [0043]     Referring to  FIGS. 3 and 4 , the dynamic miscompare module  230  indicates a miscompare message indicator  400  upon determining a miscompare condition in step  350 . The miscompare message indicator  400  includes a miscompare cue  410  and a miscompare descriptor  420 . The balloon-like shape of the miscompare cue  410  is merely illustrative and is not intended to limit the present invention. The miscompare cue  410  may assume a variety of shapes, e.g., a rectangle, a square, an ellipse, a circle, a triangle, or a polygon. Alternatively, the miscompare cue  410  may have a diagrammatical shape, e.g., a callout balloon. One of ordinary skill in the art will readily appreciate the general principles of the present invention are not limited by the shape selected for the miscompare cue  410 .  
         [0044]     Still referring to  FIG. 4  the miscompare descriptor  420  may be English text (e.g., “Heading Miscompare”), but may also be non-English text, e.g., traditional Chinese. The miscompare descriptor  420  may also be an alphanumerical character string, e.g., “HDG MIS=10 DEG.” Although the miscompare descriptor  420  is described as being text or an alphanumerical character string, combinations thereof known in the art are also within the contemplation of the present invention. Similarly, symbols, graphics and combinations thereof known in the art are also with the contemplation of the present invention. One of ordinary skill in the art will readily appreciate these embodiments and combinations thereof are all within the contemplation of the present invention.  
         [0045]     Additionally, the miscompare descriptor  420  is not necessarily limited to describing a miscompare condition (e.g., “Heading Miscompare”), but may also provide status (e.g., “Heading Comparator Enabled”) or a query for a response, e.g., “Heading Miscompare, Ignore? [Y/N].” 
         [0046]     Forming an indicated miscompare message indicator  400  as a miscompare cue  410  and a miscompare descriptor  420  allows an operator to readily discern, ascertain, and comprehend which instrumentation datum  430  is unreliable. For example, shaping the miscompare cue  410  as a rectangle alerts an operator of a miscompare condition visually. As another example, printing the miscompare descriptor  420  as English text alerts an operator of a miscompare condition textually.  
         [0047]     Referring to  FIGS. 3 and 4 , the dynamic miscompare module  230  indicates a miscompare message indicator  400  upon determining a miscompare condition in step  350 . In one embodiment of the present invention, the dynamic miscompare module  230  interposes between the miscompare message indicator  400  and the instrumentation datum  430  a leader  440  when a miscompare condition arises.  
         [0048]     For example, when a miscompare condition for airspeed arises, the dynamic miscompare module  230  interposes a leader between a miscompare message indicator for airspeed and an instrumentation datum for airspeed. As such, in addition to being alerted by the miscompare message indicator for airspeed itself, an operator is also alerted to the miscompare condition for airspeed by the leader interposed between of the miscompare message indicator for airspeed and the instrumentation datum for airspeed.  
         [0049]     Alternatively, in another embodiment of the present invention, the dynamic miscompare module  230  locates the miscompare message indicator  400  proximally to the instrumentation datum  430  when a miscompare condition arises and the instrumentation datum  430  is unreliable.  
         [0050]     For example, when a miscompare condition for airspeed arises, the dynamic miscompare module  230  locates a miscompare message indicator for airspeed proximally to an instrumentation datum for airspeed. As such, in addition to being alerted by the miscompare message indicator for airspeed itself, an operator is also alerted to the miscompare condition for airspeed by the proximity of the miscompare message indicator for airspeed to the instrumentation datum for airspeed.  
         [0051]     Rather than limiting the present invention, interposing a leader between the miscompare message indicator  400  and the instrumentation datum  430 , and locating the miscompare message indicator  400  proximally to the instrumentation datum  430  are examples of the dynamic miscompare module  230  indicating a miscompare condition. Other examples exist and are within the contemplation of the present invention. For example, the dynamic miscompare module  230  may indicate a miscompare condition with an auditory indicator such as a buzzer or a recorded voice.  
         [0052]      FIG. 5  is a block diagram illustrating the exemplary dynamic miscompare module  230  of  FIG. 2 . The dynamic miscompare module  230  includes a receiver sub-module  510 , a calculator sub-module  515 , a measurement sub-module  520 , a comparison sub-module  525  and an indicator sub-module  530 . Alternatively, some or all of the aforementioned sub-modules may not be co-located, but may be remotely located and connected to one another via a data communication bus (not shown).  
         [0053]     A plurality of instrumentation data  508  is received by the receiver sub-module  510  resulting in a received plurality of instrumentation data  512 .  
         [0054]     The calculator sub-module  515  calculates a difference in the received plurality of instrumentation data  512 . The result of the calculation is a calculated difference in plurality of instrumentation data  517 .  
         [0055]     The measurement sub-module  520  measures over time a change in the received plurality of instrumentation data  512 . The result of the measurement is a measured change in plurality of instrumentation data  522 .  
         [0056]     The comparison sub-module  525  compares the calculated difference in plurality of instrumentation data  517  to a total (or a sum) of the measured change in plurality of instrumentation data  522  and a threshold value  523 .  
         [0057]     When the calculated difference in plurality of instrumentation data  517  is greater than the total of the measured change in plurality of instrumentation data  522  and the threshold value  523 , the indicator sub-module  530  indicates a miscompare message indicator  532 . The miscompare message indicator  532  provides an indication of the reliability of an instrumentation datum.  
         [0058]     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.  
         [0059]     For example, in addition to indicating a flight parameter miscompare (i.e., a miscompare condition in a flight parameter such as pitch attitude) the dynamic miscompare module of the present invention may also indicate a miscompare condition in Very High Frequency (VHF) navigation information.  
         [0060]     For example, the dynamic miscompare module indicates or otherwise presents a localizer miscompare in an event a first horizontal deviation from a first identically tuned navigation radio and at least one second horizontal deviation from a second identically tuned navigation radio do not satisfy a condition. By way of example, the dynamic miscompare module indicates the localizer miscompare in an event the first and second horizontal deviations are valid and differ by more than 0.0775 depth of differential modulation (ddm).  
         [0061]     In another example, the dynamic miscompare module indicates or otherwise presents a glideslope miscompare in an event a first vertical deviation from a first identically tuned navigation radio and at least one second vertical deviation from a second identically tuned navigation radio do not satisfy a condition. By way of example, the dynamic miscompare module indicates the glideslope miscompare in an event the first and second vertical deviations are valid and differ by more than 0.0875 ddm, but does not indicate the glideslope miscompare during a backcourse.  
         [0062]     In yet another example, the dynamic miscompare module indicates or otherwise presents a VHF Omnirmage (VOR) miscompare in an event a first VOR bearing from a first identically tuned navigation radio and at least one second VOR bearing from a second identically tuned navigation radio do not satisfy a condition. By way of example, the dynamic miscompare module indicates the VOR miscompare in an event the first and second VOR bearings are valid and differ by more than 4 degrees, but not indicating a VOR miscompare in an event the first and second VOR bearings are changing by more than 3 degrees/second.  
         [0063]     In yet another example embodiment, the dynamic miscompare does not indicate a miscompare message indicator for a period of time in an event a navigation frequency used by the first navigation radio and at least one second navigation radio is changed.  
         [0064]     In still yet another example embodiment, the dynamic miscompare does not indicate a miscompare message indicator in an event a miscompare condition is indicated from a period of time.  
         [0065]     In still yet another example embodiment, the dynamic miscompare does not indicate a miscompare message indicator in an event that an airspeed is less than a minimum steady flight speed at which an airplane is controllable in a landing configuration (or VS 0 )+5 knots.