Patent Publication Number: US-9846437-B2

Title: Upgraded flight management system for autopilot control and method of providing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application No. 62/175,138 filed on Jun. 12, 2015 and is a continuation of U.S. patent application Ser. No. 15/177,288 filed on Jun. 8, 2016, which is a continuation-in-part of U.S. patent application Ser. No. 14/736,084 filed on Jun. 10, 2015 (now, U.S. Pat. No. 9,595,199), which is a continuation application of U.S. patent application Ser. No. 13/109,747, filed on May 17, 2011 (now U.S. Pat. No. 9,087,450). All of the above-identified applications are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to flight management systems (“FMS”) for use on board an aircraft, such as for interfacing with the flight crew and assisting in the control of an aircraft throughout flight, and more particularly relates to the upgrading of preexisting flight management systems previously provided on the aircraft in order to update the preexisting FMS to provide increased functionality, autopilot control, and auto-throttle control while attempting to cannibalize and optimize the utilization of various costly components of the preexisting on board flight management system. 
     BACKGROUND OF THE INVENTION 
     The longevity of aircraft, particularly aircraft used in commercial aviation, usually far exceeds changes in the level and capabilities of on board equipment used to assist the flight crew in controlling the aircraft. Thus, the aircraft manufacturer, or the customer, such as a commercial airline, in their desire to upgrade their equipment with the latest technology, such as regarding on board flight management systems (“FMS”) is faced with considerable expense, and downtime, in attempting to upgrade the existing aircraft with the latest technology. In many instances, particularly regarding commercial aviation, this may not be a mere matter of competitive choice but may be mandated by a regulatory agency, such as the Federal Aviation Administration. In the case of commercial fleets involving substantial numbers of aircraft this can be quite costly and time consuming, but necessary as the cost of the aircraft involved, and the time to construct them, leaves very little choice but to retrofit the existing fleet. 
     One such area where there have been considerable changes which improve the capability and efficiency of the aircraft is in the area of flight management systems which have now needed to be updated to keep up not only with competitive pressures, but with the latest capabilities and functionality desired by the FAA as well. A typical example of this is with respect to the preexisting flight management system on board a typical conventional MD-80/90 aircraft which is a work horse of many airline fleets and has been utilized by the airlines for many years. Such aircraft, despite their long use, still have many flying hours left but need the preexisting on board flight management system to be replaced or upgraded to keep up with modern needs and requirements. These preexisting systems, such as the preexisting flight management system on board a typical MD-80/90 aircraft, which were satisfactory when they were originally installed on board the aircraft, and have previously been for several years thereafter, generally have a legacy EFIS system which, in today&#39;s environment, results in various existing system shortcomings, such as providing limited FMS Navigation database storage capacity, lacking a desired required time of arrival or RTA capability, and lacking the ability to provide RNP VNAV, LPV and RNAV capability utilizing a GPS or global positioning system based navigation solution or the ability to control the autopilot and auto-throttle functions during different phases of flight such as Instrument Landing System approach and also provide the ability to optimize these functions through constant monitoring of the aircraft&#39;s flight parameters. 
     Prior art efforts in this area, in order to meet these and other current needs in preexisting aircraft still having considerable life, have involved the often costly and inefficient complete replacement of the preexisting flight management system with an entirely new system. This was the typical approach previously utilized rather than attempting to take advantage of various key legacy components in a retrofitted system, such as by overcoming these preexisting system shortcomings by replacing the legacy EFIS system with other components while optimizing the usage of preexisting legacy components from the prior on board flight management system, such as the legacy advance flight management computer or AFMC which in the navigation solution utilized on preexisting aircraft, such as the MD-80/90, relies on a single AFMC to calculate such parameters as lateral guidance, vertical guidance, and performance calculations. Thus, it would be desirable in any navigation upgrade solution for preexisting aircraft to be able to retain the legacy AFMC in any upgraded navigation solution for that aircraft, rather than replace the preexisting FMS system completely so as to be able, inter alia, to exploit the previously proven performance capabilities of the on board AFMC. In addition, because these preexisting flight management systems were not originally intended to utilize the type of GPS based navigation solutions preferred today, they did not have the capability of utilizing a GPS based navigation solution, such as to provide RNP, VNAV, LPV and RNAV capability. 
     Accordingly, a need or potential for benefit exists for viable upgraded flight management systems that can take advantage of and retrofit or cannibalize preexisting on board FMS system components, including the on board AFMC, in order to efficiently and cost effectively upgrade the capabilities of the preexisting FMS system to at least include improved GPS-based navigation and autopilot/auto-throttle functionality without having to completely replace it. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a preexisting flight management system or FMS, such as a legacy MD-80/90 FMS system, is upgraded to increase its functionality while still employing certain preexisting components of the legacy system, such as the advanced flight management computer or AFMC, the inertial reference unit or IRU, the central air data computer or CADC, the distance measuring equipment receiver (DME) receiver, and the digital flight guidance computer or DFGC, while replacing other preexisting components, such as the legacy EFIS system, with different components providing enhanced functionality for the FMS system. Such systems which provide for at least increased navigation database storage capacity and Ground Positioning System (GPS) navigation solutions extending the functionality of the preexisting FMS are described in U.S. Pat. No. 9,087,450 entitled Upgraded Flight Management System and Method of Providing The Same” by Geoffrey S. M. Hedrick et al. and U.S. patent application Ser. No. 14/736,084, filed Jun. 10, 2015, now pending, entitled Upgraded Flight Management System and Method of Providing The Same” by Geoffrey S. M. Hedrick et al., both of which are incorporated in their entirety herein by reference, there is described an upgraded preexisting FMS. 
     In the reconstituted or upgraded flight management system of the present invention, the preexisting IRU, CADC, DME receiver and DFGC remain in communication with the legacy AFMC but, instead of utilizing the legacy electrical flight information system or EFIS system from the preexisting FMS system, the EFIS system is replaced by a data concentrator unit (DCU) as well as a display control panel and an integrated flat panel display, and a global positioning system or GPS receiver is added to the system to enable a GPS based navigation solution to be provided. The data concentrator unit and the legacy AFMC are operatively connected to each other for exchanging information therebetween, with the DFGC being connected to the data concentrator unit output. The GPS or global positioning system receiver is operatively connected to the data concentrator for providing input information thereto. The upgraded FMS system of the present invention also includes a replacement multipurpose control display unit (MCDU) that allows for the FMS system to have at least increased navigation database storage capacity and/or required navigation performance (RNP), vertical navigation (VNAV), area navigation (RNAV), local performance with vertical guidance (LPV) and capability utilizing a GPS based navigation solution and may have required time of arrival or RTA capability as well as well as capability to control the autopilot and auto-throttle functions, while still enabling the legacy AFMC to exploit its aircraft performance capabilities throughout the flight of the aircraft which has the upgraded FMS system on board. Specifically, the upgraded FMS is capable of controlling the autopilot during all phases of flight (e.g., take-off, cruise, approach) such as, for example, during an Instrument Landing System (ILS) approach by providing simulated ILS signals. These types of ILS signals refer to localizer and glideslope deviation signals that determine the horizontal and vertical deviation of the aircraft respectively from a pre-defined approach trajectory that can be stored in the navigation database. In such cases, the upgraded FMS and MCDU provide continuous monitoring and measuring of the vertical and horizontal path deviation of an aircraft that can be subsequently converted using the MCDU microprocessor into ILS deviation signals that are provided as an input to the autopilot through one or more ILS input channels. 
     Furthermore, in some embodiments, the upgraded FMS and MCDU are capable of optimizing the use of the autopilot and auto-throttle by continuously monitoring, during all phases of flight, the actual performance of the aircraft and obtaining measurements for actual flight parameters such as, among other things, attitude, altitude, airspeed, vertical speed, slip, heading, cross track, vertical deviation performance and three axis acceleration. The upgraded FMS can subsequently convert these measurements into control signals in order to control and adjust the autopilot and auto-throttle function by varying different parameters such as the gain and delay variables of, for example, pitch command, roll command, N1/EPR target, airspeed target and vertical speed command signals that are provided to a feedback system for adjusting the aircraft&#39;s trajectory. Moreover, optimizing the autopilot and auto-throttle functions can be achieved in an iterative manner whereby adjustments in the aircraft&#39;s trajectory are performed periodically during a detection period, thus allowing for optimizing and enhancing the performance of the autopilot installed in the aircraft. Like the preexisting flight management system, the upgraded flight management system of the present invention may employ a redundant system connected to the legacy AFMC so that, for example, the pilot and first officer each have a duplicate set of controls. In such an instance, the upgraded system of the present invention would include a second IRU, a second CADC, a second DME receiver, a second DFGC, a second data concentrator unit, and a second global positioning receiver while still utilizing the common legacy AFMC. Thus, as will be explained in greater detail below with reference to the drawings, the upgraded flight management system of the present invention provides a viable and cost effective solution to upgrade a preexisting flight management system while increasing functionality and overcoming shortcomings of the preexisting system, such as, for example, increasing FMS navigation database storage capacity, providing RNP VNAV, LPV and RNAV capability utilizing a GPS based navigation solution, providing required time of arrival or RTA capability and optimizing autopilot/auto-throttle functionality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To facilitate further description and understanding of the present invention, the following drawings are provided in which: 
         FIG. 1  is a representative block diagram illustrating a typical conventional prior art preexisting legacy flight management system, such as the legacy MD-80/90 Nav System available on a conventional MD-80/90 commercial aircraft; 
         FIG. 2  is a representative block diagram illustrating the upgraded preexisting flight management system, according to the present invention in which the system of  FIG. 1  has been upgraded in accordance with the present invention; 
         FIG. 3A  is a representative diagrammatic illustration of an MD-80/90 aircraft with the upgraded preexisting flight management system of  FIG. 2  on board; 
         FIG. 3B  is a representative system flow chart of the software employed to carry out the related functions of the Navigator portion of the MCDU in the upgraded system of  FIG. 2 ; 
         FIGS. 4A and 4B  form  FIG. 4  and are partial views of a representative flow chart illustrating a typical preferred method in accordance with the present invention for upgrading a preexisting flight management system, such as the flight management system of  FIG. 1 , to achieve the presently preferred embodiment illustrated in  FIG. 2 . 
         FIG. 5  is a flow diagram illustrating a method of controlling the autopilot through the upgraded FMS. 
         FIG. 6  is a flow diagram illustrating a method of optimizing the autopilot and auto-throttle through the upgraded FMS. 
         FIG. 7  is a flow diagram illustrating a method of iteratively controlling the autopilot and auto-throttle through the upgraded FMS. 
         FIG. 8  is a diagrammatic illustration comparing an exemplary standard flight plan generated by the upgraded flight management system of  FIG. 2  to an alternate loaded flight plan; 
         FIG. 9  is a diagrammatic illustration of an exemplary AFMC initialization page accessible through the MCDU in the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIGS. 10A and 10B  are diagrammatic illustrations of an exemplary AFMC position initialization and position reference page, respectively, accessible through the MCDU in the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 11  is a diagrammatic illustration of an exemplary AFMC performance initialization page accessible through the MCDU in the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 12  is a diagrammatic illustration of an exemplary AFMC takeoff reference page accessible through the MCDU in the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 13  is a diagrammatic illustration of an exemplary AFMC approach reference page accessible through the MCDU in the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 14  is a diagrammatic illustration of an exemplary legacy AFMC LEGS page transferred to the AFMC using the MCDU interface in accordance with the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 15  is a diagrammatic illustration of an exemplary AFMC climb page accessible through the MCDU in accordance with the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 16  is a diagrammatic illustration of an exemplary AFMC engine out climb page accessible from the climb page of  FIG. 15  in accordance with the present invention in the upgraded flight management system of  FIG. 2 ; 
         FIG. 17  is a diagrammatic illustration of an exemplary AFMC economy cruise page accessible from the MCDU in accordance with the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; 
         FIG. 18  is a diagrammatic illustration of an exemplary AFMC engine out cruise page accessible from the cruise page of  FIG. 14  in accordance with the present invention in the upgraded flight management system of  FIG. 2 ; 
         FIG. 19  is a diagrammatic illustration of an exemplary AFMC economy descent page accessible from the MCDU in accordance with the upgraded flight management system of the present invention as illustrated in  FIG. 2 ; and 
         FIG. 20  is a diagrammatic illustration of an exemplary AFMC descent forecast page accessible from the descent page of  FIG. 19  in accordance with the present invention in the upgraded flight management system of  FIG. 2 . 
     
    
    
     For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements. 
     The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus. 
     The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. 
     The terms “connect,” “connected,” “connects,” “connecting,” “couple,” “coupled,” “couples,” “coupling,” and the like should be broadly understood and refer to linking two or more elements or signals, electrically, mechanically and/or otherwise. Two or more electrical elements may be electrically connected/coupled but not be mechanically or otherwise connected/coupled; two or more mechanical elements may be mechanically connected/coupled, but not be electrically or otherwise connected/coupled; two or more electrical elements may be mechanically connected/coupled, but not be electrically or otherwise connected/coupled. Connecting/coupling may be for any length of time, e.g., permanent or semi-permanent or only for an instant. 
     “Electrical connecting,” “electrical coupling,” and the like should be broadly understood and include connecting/coupling involving any electrical signal, whether a power signal, a data signal, and/or other types or combinations of electrical signals. “Mechanical connecting,” “mechanical coupling,” and the like should be broadly understood and include mechanical connecting/coupling of all types. 
     The absence of the word “removably,” “removable,” and the like near the word “connected” and/or “coupled,” and the like does not mean that the connecting and/or coupling, etc. in question is or is not removable. 
     The term “primary” in the description and in the claims, if any, is used for descriptive purposes and not necessarily for describing relative importance. For example, the term “primary” can be used to distinguish between a first component and an equivalent redundant component; however, the term “primary” is not necessarily intended to imply any distinction in importance between the so-called primary component and the redundant component. Unless expressly stated otherwise, any redundant component(s) should be treated as being able to operate interchangeably with any primary component(s) of the system, in tandem with any primary component(s), and/or in reserve for any primary component(s) (e.g., in the event of a component/system failure). 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail, and initially to  FIG. 1 , it is believed that a brief explanation of  FIG. 1 , which illustrates a typical prior art legacy MD-80/90 Nav system  100  of the type normally found on board conventional MD-80/90 aircraft, would be helpful in understanding the subsequent explanation of the upgrading of such a legacy system  100  in accordance with the present invention. For purposes of illustration, a presently preferred embodiment of such an upgraded flight management system  200  is illustrated in  FIG. 2 , with like reference numerals being utilized in  FIG. 2  for the preexisting or legacy components of the preexisting flight management system of  FIG. 1  which remain after the upgrading of the system of  FIG. 1  has taken place in accordance with the present invention. As illustrated in  FIG. 1 , the prior art or preexisting flight management system  100  which is to be upgraded in accordance with the present invention will be described, by way of example, with reference to a conventional legacy MD-80/90 Nav system of the type normally provided on board preexisting MD-80/90 aircraft provided by the Boeing Company and previously through McDonnell Douglas Corporation now a part of the Boeing Company. 
     As shown in  FIG. 1 , the conventional prior art preexisting flight management system or FMS  100  provided on board a typical MD-80/90 aircraft, normally includes redundant systems for the pilot and first officer. The redundant FMS system  100  which preexisting MD-80/90 aircraft are normally equipped with includes two conventional inertial reference units or IRU  110 ,  120 ; two conventional very high frequency navigation (VHF NAV) receivers  116 ,  118 ; two conventional DME receivers  112 ,  122 ; a conventional marker beacon receiver  119 ; two conventional multipurpose control display units or MCDU  130 ,  132 ; a common conventional advance flight management computer or AFMC  105 ; two conventional central air data computers or CADC  111 ,  121 ; and two conventional flight guidance computers or DFGC  113 ,  123 . In addition, as also illustrated in  FIG. 1 , the preexisting conventional FMS system  100  also normally includes conventional symbol generators  134 ,  136 ; a conventional system clock  138  for providing GMT to the AFMC  105 ; two conventional VHF omnidirectional radios or VOR  140 ,  142 ; two conventional DME tuning converters  144 ,  146 ; and a pair of conventional flight displays  148 ,  150  for conventionally displaying flight information to the pilot and first officer comprising the flight crew. As further illustrated in  FIG. 1 , the IRUs  110 ,  120  are connected to the AFMC  105 , and to the symbol generators  134 ,  136 , respectively, through an ARINC 429 data bus; the CADCs  111 ,  121  are connected to the AFMC  105 , and to the symbol generators  134 ,  136 , respectively, through an ARINC 575 data bus; and the DMEs  112 ,  122 , the VORs  140 ,  142 , and the DFGCs  113 ,  123 , are connected to the AFMC  105  through an ARINC 429 data bus as well. In the conventional prior art legacy MD-80/90 navigation solution illustrated by the FMS system  100  of  FIG. 1 , the common AFMC  105  is utilized to calculate Lateral Guidance, Vertical Guidance, and Performance Calculations for the aircraft. In so doing, the AFMC  105  relies on dual INU input for position data and conventionally generates a blended position solution by applying corrections based on DME distance from known references. 
     As will be explained in greater detail below, with reference to  FIG. 2 , the upgraded FMS system  200  of the present invention is believed to provide a viable and cost effective solution for upgrading preexisting flight management systems, such as the preexisting flight management system or FMS  100  illustrated in  FIG. 1 , preferably increasing functionality and overcoming existing system shortcomings, given today&#39;s requirements, found to be present in prior art flight management systems, such as the prior art FMS system  100  illustrated in  FIG. 1 . For example, as will be explained below, it is expected that the upgraded FMS system  200  of the present invention, will increase the FMS Navigation database storage capacity, provide RNP VNAV, RNAV and LPV capability utilizing a GPS based navigation solution, and/or provide Required Time of Arrival or RTA capability as well as capability to control the autopilot and auto-throttle functions, all of which assist in increasing the functionality of and overcoming system shortcomings of the prior art preexisting FMS system  100  being upgraded in accordance with the present invention. 
     Referring now to  FIG. 2 ,  FIG. 2  illustrates an upgraded preexisting flight management system (FMS)  200  in accordance with the present invention, with any preexisting components of the preexisting FMS system  100  which is being upgraded which remain in the upgraded FMS system  200  having the same reference numerals as utilized in  FIG. 1 . The upgraded preexisting FMS system  200  being described with reference to  FIG. 2  is merely exemplary of such upgraded systems in accordance with the present invention and the invention is not intended to be limited to the embodiments presented herein. 
     As shown and preferred in  FIG. 2 , the upgraded FMS system  200  preferably retains the legacy AFMC  105  previously present in the preexisting flight management system  100  as well as the legacy IRUs  110 ,  120 , CADCs  111 ,  121 , VHF NAV Receivers  116 ,  118 , DME Receivers  112 ,  122 , and DFGCs  113 ,  123 . The legacy AFMC  105  is preferably retained in the upgraded FMS system  200  in order to exploit its previously proven performance capabilities. The preexisting MCDUs  130 ,  132  are preferably replaced with new MCDUs  225 ,  255  which preferably contain navigation computers  280 ,  282  which manage the flight plan and generate lateral and vertical guidance, auto throttle controls, and configure and synchronize the legacy AFMC  105  to allow it to continue to calculate the aircraft performance parameters throughout the flight. Preferably the AFMC performance based pages which appear on the MCDU  225 ,  255  are accessible through the MCDUs  225 ,  255  via ARINC 739 protocol, with such performance based pages being illustrated, by way of example, in  FIGS. 8-20 . 
     Preferably, the AFMC  105  performance data in the upgraded FMS system  200  of  FIG. 2  is utilized to provide estimated time of arrival for each leg of the flight and to the final destination; predicted leg speed and altitude leg cruise winds; progress such as distance to go, ETA and fuel remaining; current speed mode such as parameters associated with LRC/ECON, selected airspeed or mach, limited speed such as VMO, MMO, Flap, Alpha; speed override, and engine out mode; top of descent; top of climb; step climbs; and fuel quantity and fuel used. The desired flight plan route is preferably entered into and calculated by the NAV computer  280 ,  282 , which is preferably RNP capable. In the presently preferred system  200  of the present invention, the flight planning pages are formatted to replicate the existing AFMC  105  pages. Preferably, a subset of the flight plan is automatically transferred to the legacy AFMC  105  from the NAV computers  280 ,  282  located in the MCDUs  225 ,  255 , respectively, via a conventional ARINC 739 interface therebetween. Preferably, in the upgraded FMS system  200  of the present invention, this subset of the flight plan consists of the origin, destination and interim waypoints. Waypoints on the SIDS and STAR are preferably transferred to the legacy AFMC  105  via lat long data since the AFMC  105  database in accordance with the present invention will not include all required terminal procedures thereby allowing it to hold a smaller database, thereby assisting the upgraded FMS system  200  in overcoming memory limitation issues present in the preexisting FMS system  100 . 
     Preferably, in the upgraded FMS system  200  of the present invention, the legacy AFMC  105  now preferably calculates the top of descent and top of climb waypoints based on best performance for the aircraft and transmits these waypoints on an ARINC 702 data bus to respective data concentrator units  201 ,  251 . The DCUs  201 ,  251  are respectively connected to the NAV computers  280 ,  282 , and preferably relay this information to the NAV computers  280 ,  282  which, preferably, in turn, include them in the flight profile for the aircraft. 
     The AFMC  105  preferably provides an interface page which allows for waypoint insertion referenced by Latitude and Longitude. Depending on the legacy AFMC  105  employed, this interface may be limited by format, such as to 1/10 th  of a minute or one decimal place accuracy for both Latitude and Longitude values. In such an instance, the resolution of the equivalent AFMC waypoint would be limited, such as to approximately 608 feet; however, it is believed that such an inaccuracy would not be significant to the Performance solution calculated by the AFMC  105 , and would not be relevant to the Lateral and Vertical guidance provided by the NAV computers  280 ,  282 . 
     Referring now to the inertial reference units or IRUs  110 ,  120  employed in the upgraded FMS system  200  of the present invention, these IRUs  110 ,  120  are the primary source of position data, i.e. latitude and longitude, utilized by the legacy AFMC  105  to generate the navigation solution for the upgraded FMS system  200 . It is a known fact that normally the IRU position is most accurate immediately after initialization or alignment and normally degrades throughout the flight until such time as the IRU is realigned. In the presently preferred upgraded FMS system  200  of the present invention, the NAV computers  280 ,  282  preferably rely on the position data from the IRUs  110 ,  120 , respectively, augmented with conventional dual Beta 3 GPS receivers  202 ,  252 , respectively, for primary navigation. Preferably, a Kalman filter algorithm is utilized to blend the GPS data with the IRU position data, with this blended GPS/IRU data preferably being transmitted to the AFMC  105  in place of the normal IRU generated data. In accordance with the present invention, in instances where the GPS data may not be available for any extended amount of time, data from the DME Receivers  112 ,  122  is preferably used to augment the IRU position information. In addition, preferably the NAV computers  280 ,  282  may include an MCDU page which could allow the IRUs  110 ,  120  to be aligned while the aircraft is at the gate. Furthermore, preferably the IRU  110 ,  120  position can be re-initialized using GPS position and time data if desired. 
     In the presently preferred upgraded FMS system  200  of the present invention, the NAV computers  280 ,  282  preferably interface directly with the digital flight guidance computers or DFGC  113 ,  123 , respectively, in order to maintain control authority of the provided autopilot and the auto-throttle functions at all times. Specifically, the upgraded FMS system  200  is able to inform the autopilot that the aircraft is performing an Instrument Landing System (ILS) approach. A simulated ILS approach is computed by at least the NAV computers  280 ,  282  along with DCUs  201 ,  251 , GPS  202 ,  252 , and display control panels  230 ,  260 . The simulated ILS approach is subsequently provided to the through an ILS input channel. 
     Furthermore, the presently preferred navigation solution provided by the upgraded FMS system  200 , in addition to the aforementioned class Beta-3 GPS receivers  202 ,  252 , utilizes two conventional TSO-C190 antennas, with the GPS receivers  202 ,  252 , by way of example, being TSO-C145c class Beta-3 GPS receivers. The resultant GPS signal is preferably fed to the respective DCUs  201 ,  251  to be used for augmentation of position information from the IRUs  110 ,  120 , respectively. 
     The presently preferred navigation solution in the upgraded FMS system  200  is preferably built around the two NAV computers  280 ,  282 , which, by way of example, are DO-229D, DO-238A and DO-236B compliant and RNP capable. These NAV computers  280 ,  282 , by way of example, are TSO-C146c-Gamma 3 compliant with additional RNAV and VNAV RNP capabilities and are preferably respectively housed within the MCDU  225 ,  255  enclosure for reducing space and power requirements although, if desired, they need not be housed there. By way of example, in the illustrated FMS system  200  of the present invention, described with respect to the MD-80/90 FMS system, each of the NAV computers  280 ,  282  is preferably RNP 0.3 capable without the database limitations of the preexisting AFMC  105 . Preferably, the FMS menu structure in the upgraded FMS system  200  replicates that of the preexisting AFMC  105  but provides additional features designed to emulate the conventional styled menus. 
     Each of the MCDUs  225 ,  255  preferably contains microprocessors making them capable of performing control logic, something which is unavailable in the legacy equipment being upgraded. Each MCDU  225 ,  255  preferably supports peripheral equipment, such as ACARS, through conventional ARINC 739A compliant interfaces, with the respective MCDUs  225 ,  255  also preferably acting as the interface to the AFMC  105  via an ARINC 739A interface as well. 
     The NAV computers  280 ,  282  in the present invention are preferably able to calculate Required Time of Arrival or RTA for any flight plan waypoint as well as required leg airspeed to meet RTA constraints. The presently preferred NAV computers  280 ,  282  preferably provide RTA capabilities to any specific waypoint through the LEGS menu page. In this regard, when an RTA is established at one of the flight plan waypoints, the respective NAV computer  280 ,  282  commands the leg speeds for he legs leading up to that waypoint to achieve the required time of arrival. Preferably a boundary checking of the commanded airspeed is performed to assure that the aircraft is being operated within a safe airspeed envelope and a warning is preferably provided to the pilot if the RTA is not obtainable due to safe airspeed restrictions. 
     The AFMC  105  preferably continuously calculates the estimated time of arrival or ETA for each of the legs in the flight plan based on the current aircraft performance and the NAV computer  280 ,  282  uses this ETA to determine the speed needed to reach the designated waypoint at the RTA. Preferably, as the flight progresses, the NAV computers  280 ,  282  monitor the calculated ETAs and modify the leg speeds accordingly. Each flight plan leg is preferably analyzed to determine the appropriate speed constraints which need to be followed, with the AFMC  105  leg speed based on best performance preferably being used by the NAV computer  280 ,  282  in cases where an RTA has not been specified. 
     Preferably, flight path discontinuities are resolved by the NAV computers  280 ,  282  and transmitted to the AFMC  105  as flight plan modifications. Although the AFMC  105  normally assumes direct point to point legs when its flight plan is created by connecting Latitude/Longitude coordinates, any slight deviation, such as due to flight path discontinuities, preferably does not create a significant error in the AFMC  105  computed performance data. Transferring the flight plan using Latitude/Longitude coordinates excludes all curved RF type legs which can result in a deviation from the defined path. However, this deviation can be minimized in accordance with the present invention by inserting additional waypoints to approximate the curved path and, hence, minimize any significant impact on the performance calculations of the AFMC  105 . This is illustrated in  FIG. 8  which illustrates the transfer of curved legs to the AFMC  105 . It should be noted that while speed constraints may be manually entered per leg to satisfy RTA requirements or determined from the AFMC  105 , constraints associated with published procedures and aircraft limitations would preferably be used to provide a not to exceed envelope for airspeed. Preferably the RTA can be primarily achieved by adjusting the speeds prior to top of descent. 
     As discussed above various performance calculations are preferably obtained from the AFMC  105  and used by the navigation computers  280 ,  282 . For example, the ETA for each leg and to the final destination, is preferably made available to the navigation computers  280 ,  282  by querying the AFMC  105  via the A739 progress page. The information is preferably received via textual data and is translated by the navigation computers  280 ,  282  to numeric format. The navigation computers  280 ,  282  then preferably use this data to cross check the RTA performance. 
     Another performance calculation is preferably the predicted leg speed and altitude leg cruise winds. Generally, this information is not required by the navigation computers  280 ,  282  and is only displayed for pilot information and modification as part of the conventional A739 interface. Similarly, distance to go, ETA, and fuel remaining are also not generally required by the navigation computers  280 ,  282  and are only displayed for pilot information. This is also preferably true for current speed modes and fuel quantity and fuel used as well, which are not required by the navigation computers  280 ,  282  and only displayed for pilot information and modification as part of the conventional A739 interface. 
     Still another performance calculation is top of descent which is preferably calculated based on the pilot entry of end of descent. This information is preferably transmitted from the AFMC  105  to the DCUs  201 ,  251  via ARINC 702 protocol and inserted to the flight profile by the navigation computers  280 ,  282  after boundary check are performed on the data. Preferably, at the top of descent, the navigation computers  280 ,  282  command idle thrust and pitch down to track the target airspeed obtained from the AFMC/DFGCs  105 ,  113 ,  123  transmit bus. The command airspeed is preferably boundary checked by the navigation computers  280 ,  282  prior to transmission to the respective DFGCs  113 ,  123 . Preferably, any modifications to the target EPR and/or target airspeed is monitored and passed along to the respective DFGCs  113 ,  123  after boundary checking is performed by the navigation computers  280 ,  282 . 
     Yet another performance calculation which is preferably performed is top of climb which is preferably calculated based on the climb limit thrust to each altitude constraint. The top of climb is preferably transmitted from the AFMC  105  to the DCUs  201 ,  251  via ARINC 702 protocol and inserted to the flight profile by the respective navigation computers  280 ,  282 . Preferably, during the climb, the AFMC  105  calculates required thrust and pitch. The navigation computers  280 ,  282  command climb limit thrust and pitch to track the profile obtained from the AFMC/DFGCs  105 ,  113 ,  123  transmit bus. The commands are preferably boundary checked by the navigation computers  280 ,  282  prior to transmission to the respective DFGCs  113 ,  123 . Preferably, any modifications to the auto-throttle commands and/or pitch is monitored and passed along to the respective DFGCs  113 ,  123  after boundary checking is performed by the navigation computers  280 ,  282 . 
     Still another performance calculation preferably being performed are the step climb points which are preferably calculated by the AFMC  105  based on optimum altitude and selected economy modes. Preferably, during the climb of the aircraft, the AFMC  105  calculates required thrust and pitch. The navigation computers  280 ,  282  preferably command climb limit thrust and pitch to track the profile obtained from the AFMC/DFGCs  105 ,  113 ,  123  transmit bus. The commands are preferably boundary checked by the navigation computers  280 ,  282  prior to transmission to the respective DFGCs  113 ,  123 . As with the top of climb, for step climbs as well, any modifications to the auto-throttle commands and/or pitch is preferably monitored and passed along to the DFGCs  113 ,  123  after boundary checking is performed by the respective navigation computers  280 ,  282 . 
     As was previously discussed, the navigation computers  280 ,  282  preferably govern the auto-throttle, pitch and roll commands to the respective DFGC  113 ,  123  during all phases of flight of the aircraft. During the approach phase for the aircraft, less priority is preferably given to the performance related pitch and auto-throttle commands provided by the AFMC  105 . The control command are preferably computed and enforced by the navigation computers  280 ,  282  to maintain the vertical, horizontal and optimum airspeeds for the required approach path for the aircraft through final approach. Preferably, guidance during missed approach for the aircraft is also computed and maintained by the navigation computers  280 ,  282  in order to meet RNP requirements. 
     Furthermore, the upgraded preexisting FMS provides for monitoring the performance of the aircraft by measuring at least the attitude, altitude, airspeed, vertical speed, slip, heading, cross track, vertical deviation performance and the three axis acceleration in all conditions of flight in order to optimize the autopilot performance. Specifically, a feedback system is employed using at least NAV computers  280 ,  282  that allows for adjusting the autopilot by using control signals. For example, the control signals can be adjusted by obtaining measurements during the maneuvering of the aircraft that are subsequently used to adjust the control signals by varying the gain and delay variables of the control system. Said control signals are subsequently provided to the autopilot in DFGC  113 ,  123  in order to adjust its performance. 
     With respect to the menu interface being preferably provided, the MCDU  225 ,  255  preferably utilizes the existing AFMC  105  menu structure via the ARINC 739 protocol for all performance pages. The navigation computers  280 ,  282  preferably replicate the menu structure of the existing AFMC  105  for flight planning in order to help minimize pilot training on the upgraded system  200  so as to, preferably, help make the operations of the upgraded FMS system  200  of the present invention as seamless a transition as possible from the prior preexing flight management system  100  which the flight crew had been familiar with on the aircraft in which the FMS system has been upgraded. In this regard, preferably the navigation computers  280 ,  282  maintain absolute understanding of the AFMC  105  menu structure at all times and react to pilot entries in the same manner as in the preexisting legacy AFMC  105 . For example, the navigation computers  280 ,  282  transfer the flight plan information to the AFMC  105  via ARINC 739 protocol in the same way that the AFMC  105  expects it from the MCDU  225 ,  255 . Furthermore, the communications with the AFMC  105  is preferably based on automated use of the MCDU  225 ,  255  page interfaces, with the FMS system  200  of the present invention preferably allowing direct access to the AFMC  105  performance pages and automating communications for the various parameters located on other AFMC  105  performance pages, as will be discussed in greater detail with respect to  FIGS. 8-20 . 
     As shown and presently preferred in  FIG. 2 , the displays  148  and  150  of  FIG. 1  may be comprised of conventional integrated flat panel displays  235 ,  265 , respectively, having associated conventional display control panels  230 ,  260 , respectively, with the respective display control panels  230 ,  260  being connected between the associated flat panel display  235 ,  265  and the corresponding MCDU  225 ,  255 , as well as being connected to the respective DCU  201 ,  251 , as shown in  FIG. 2 . 
     As diagrammatically illustrated in  FIG. 3A , the presently preferred flight management system  200  is located on board the aircraft  300  for enabling control of the aircraft  300  by the flight crew. As was previously mentioned, the legacy AFMC  105  contained in the upgraded FMS system  200  on board the aircraft  300  is preferably still able to exploit its aircraft performance capabilities throughout the flight of the aircraft  300 . In this regard, as will be explained below with reference to  FIGS. 8-20 , since, preferably, the legacy AFMC  105  is what is utilized for performance calculations in the upgraded FMS system  200  of the present invention, the menu pages relating to performance are preferably directly accessible through the MCDU  225 ,  255 . In this regard, these initialization pages include such pages as PERFORMANCE INIT, TAKEOFF REF, and APPROACH REF. 
     Before describing the performance pages in greater detail, suffice it to say that,  FIG. 3B , by way of example, illustrates a typical representative system flow chart for the software employed to enable the related functions described above of the navigation computers  280 ,  282  located in the respective MCDUs  225 ,  255  to be carried out. For example, the navigator computers  280 ,  282  may be conventionally programmed in C to carry out the functions illustrated in the system flow chart of  FIG. 3B . Suffice it say that in accordance with the system flow chart of  FIG. 3B , the MCDU/NAV units act as the primary interface to the pilot for flight planning purposes, autopilot and auto-throttle control functions. The MCDU/NAV internal navigation database is utilized to retrieve information regarding the various navigation points and aid in computation of the planned flight path. For example, in some embodiments, the internal navigation databases can include waypoints and required trajectories for an ILS approach and/or any other suitable flight path The planned flight path is then transferred to the legacy AFMC  105  to allow it to conventionally compute performance parameters for optimum fuel burn and time en-route. The legacy AFMC  105  thrust and airspeed targets are then conventionally analyzed by the navigation computers  280 , 282  and a final set of lateral, vertical, thrust and airspeed targets are then provided to the DFGCs  113 , 123 . The system flow chart is self-explanatory and need not be described in further greater detail in order to understand the presently preferred operation of the navigation computers  280 ,  282  in the upgraded FMS system  200  of the present invention. 
     Referring now to  FIG. 9 , at least one menu page can comprise an AFMC Initiation Page for providing performance calculations to legacy AFMC  105  ( FIG. 2 ). Preferably, the AFMC Initiation Page can permit access to at least one of the Performance Initiation Page, the Takeoff Reference Page, or the Approach Reference Page, as described below. 
     Referring now to  FIGS. 10A and 10B , at least one menu page can comprise a Position Initialization Page ( FIG. 10A ) and another menu page can comprise a Position Reference Page ( FIG. 10B ). The Position Initialization Page ( FIG. 10A ) can allow for initialization and/or verification of IRU  110 ,  120  ( FIG. 2 ) and/or selections for legacy AFMC  105  ( FIG. 2 ), whereas the Position Reference Page ( FIG. 10B ) allows for verification of position. 
     Referring now to  FIG. 11 , at least one menu page can comprise a Performance Initiation Page. The Performance Initiation Page can allow for entry of fuel, weight, and/or performance configurations to be provided to legacy AFMC  105  ( FIG. 2 ). 
     Referring now to  FIG. 12 , at least one menu page can comprise a Takeoff Reference Page. The Takeoff Reference Page can allow for entry of takeoff performance and reference speed configurations to be provided to legacy AFMC  105  ( FIG. 2 ). 
     Referring now to  FIG. 13 , at least one menu page can comprise an Approach Reference Page. The Approach Reference Page can allow for entry of approach performance and reference speed configurations to be provided to legacy AFMC  105  ( FIG. 2 ). 
     Referring now to  FIG. 14 , at least one menu page can comprise a legacy AFMC LEGS Page, labeled in the illustrative example as “ACT RTE 1 LEGS”. This menu page illustrates the actual route 1 LEGS Page transferred to the legacy AFMC  105  ( FIG. 2 ) using the MCDU interface in accordance with the present invention. 
     Referring now to  FIG. 15 , at least one menu page can comprise the AFMC CLIMBS Page, as referenced above, labeled “ACT 250KT CLB” in the example shown. This Page can display such parameters as cruise altitude and/or speed details for each leg of a flight of aircraft  300  ( FIG. 3A ). 
     In various embodiments, at least one menu page can comprise a Route Menu Page (not shown). In such an instance, the Route Menu Page can provide an interface by which to enter flight plans to be provided to VHF NAV receiver  116  ( FIG. 2 ) and/or legacy AFMC  105  ( FIG. 2 ). In further embodiments, at least one menu page can comprise a Holding Menu Page (not shown) to define holding patterns at a selected waypoint of the flight plans. 
     In other embodiments, at least one menu page can comprise a Departure and/or Arrival Page (not shown) to select departure and/or arrival procedures to be provided to VHF NAV receiver  116  ( FIG. 2 ). The departure and/or arrival procedures can be stored within a navigation database of VHF NAV receiver  116  ( FIG. 2 ) and transferred to legacy AFMC  105 . 
     In various embodiments, at least one menu page can comprise one or more Progress Pages (not shown), each displaying at least one of an altitude, a distance remaining, an ETA, or a fuel burn for each of the legs in a flight plan of aircraft  300  ( FIG. 3A ). In such an instance, any of this data can automatically be retrieved from legacy AFMC  105  ( FIG. 2 ). Furthermore, at least one menu page can comprise a Fix Page (not shown) for querying the navigation database of VHF NAV receiver  116  for fix information. In addition, at least one menu page can comprise a Climb Page for selecting climb performance modes and/or for specifying climb constraints (e.g., cruising altitude, climb mode, speed constraints, etc.) for aircraft  300  ( FIG. 3A ). 
     Referring now to  FIG. 16 , in some embodiments, the menu page can comprise an Engine Out Climb Page. In such an instance, the Engine Out Climb Page can provide an interface by which to recalculate climb performance based on single engine performance data. In various embodiments, the Engine Out Climb Page can be accessed through the Climb Page, as described above. 
     Referring now to  FIG. 17 , in some embodiments, the menu page can comprise a Cruise Page selecting cruise performance modes and/or for specifying cruise constraints (e.g., cruising altitude, drift down altitude, cruise airspeed, minimum safe operating speed, etc.) for aircraft  300  ( FIG. 3A ), such as the economy values illustrated in  FIG. 17 . Referring now to  FIG. 18 , the menu page can comprise an Engine Out Cruise Page to provide an interface by which to recalculate cruise performance based on single engine performance data. In many embodiments, the Engine Out Cruise Page and a Cruise Drift Down Page (not shown) can be accessible from the Cruise Page. 
     Referring now to  FIG. 19 , the menu page can comprise a Descent Page for providing an interface to define the descent phase of flight, such as the economy values illustrated in  FIG. 19 . In such an instance, the legacy AFMC  105  ( FIG. 2 ) can be configured to entries provided via the Descent Page to determine and commence descending at the top of decent point. 
     Referring now to  FIG. 20 , the menu page can comprise a Descent Forecast Page for providing an interface to define additional descent parameters (e.g., forecast winds, anti-icing, etc.). 
     Returning back now to  FIG. 4  ( FIGS. 4A-B ),  FIG. 4  illustrates an exemplary flow chart of a method  400  of upgrading a preexisting FMS, such as FMS system  100  previously described, having a legacy AFMC  105  in order to provide increased functionality over the preexisting FMS  100  for enabling the upgraded preexisting FMS  200  to be capable of having at least increased navigation database storage capacity; and/or RNP, VNAV and RNAV capability utilizing a GPS based navigation solution and/or RTA capability while still enabling the legacy AFMC to exploit its aircraft performance capabilities throughout the flight of an aircraft  300  having the upgraded preexisting FMS  200  on board. The method  400  illustrated in  FIG. 4  is merely intended to be exemplary and is not limited to the embodiments of the FMS system  200  presented herein. Method  400  can be employed in many different embodiments or examples not specifically depicted or described herein. In some embodiments, the activities, the procedures, and/or the processes of method  400  can be performed in the order presented. In other embodiments, the activities, the processes, and/or the procedures of method  400  can be performed in any other suitable order. In still other embodiments, one or more of the activities, the processes, and/or the procedures in method  400  can be combined or skipped. Thus,  FIG. 4  is just an illustration of the various steps that may be preferably performed to achieve the presently preferred upgraded FMS system  200  of the present invention from the preexisting FMS system  100  originally provided on board the aircraft  300 , keeping in mind that the steps need not be performed in any specific order as long as they ultimately result in the upgraded FMS system  200  of  FIG. 2 . 
     Referring back to  FIG. 5  and in accordance with some embodiments of the present invention, the upgraded FMS  200  is capable of controlling the autopilot using method  500  shown in  FIG. 5 . For example, when an aircraft is performing an Instrument Landing System approach, upgraded FMS  200  informs the autopilot through NAV computers  280 ,  282  of the approach (Step  302 ). At Step  304 , NAV computers  280 ,  282 , retrieve from NAV database flight measurements such as attitude, altitude, airspeed, vertical speed, slip, heading, cross track, vertical deviation performance, horizontal deviation performance and the three axis acceleration as obtained by the sensors and various components of upgraded FMS  200 . In addition, NAV database also provides the pre-defined trajectory including glide slope and localizer signals for the approach. At Step  306  process  300  converts the horizontal and vertical path deviation measurements using MCDUs  280 ,  282  to obtain localizer and glide slope deviation signals respectively eliminating the need for the pilot to keep the glide slope and localizer indicators centered on displays  235 ,  265 . Finally, at step  308  the localizer and glide slope deviation signals are provided as an input to the autopilot&#39;s ILS input channel in NAV computers  280 ,  282  using DCUs  201 ,  251  and DFGC computers  113 ,  123   
       FIG. 6 , illustrates method  600  for optimizing the use of the autopilot and auto-throttle function using the upgraded FMS  200  in accordance with some embodiments of the present invention. Specifically, at  602 , upgraded FMS measures the actual performance of the aircraft by monitoring the attitude, altitude, airspeed, vertical speed, slip, heading, cross track, vertical deviation performance and three axis acceleration using IRUs  110 ,  120 , DMEs  112 ,  122  and DFGCs  113  and  123  respectively. The obtained measurements are subsequently stored in MCDUs  280 ,  282  NAV databases for retrieval and/or processing by the AFMC  105 . At  604 , the autopilot is informed of a trajectory for a specific phase of light (e.g., a series of waypoints during cruise flight) using NAV computers  280 ,  282 . This trajectory serves as a reference for the autopilot function and provides the necessary navigation commands to upgraded FMS  200 . At  606 , deviation signals are computed using NAV computers  280 ,  282 , AFMC  105 , DFGCs  113 ,  123  and DCUs  201 ,  252  between the measured flight parameters, as referenced at  602  and the provided autopilot reference trajectory. The calculated deviation signals can be converted at  608  using MCDUs  280 ,  282  into autopilot control signals. For example, in some embodiments, the autopilot functionality can be optimized using a feedback system that allows for the adjustment of the autopilot commands to upgraded FMS  200 , as shown at  610 . Specifically, such adjustment of the autopilot functionality can involve varying parameters such as one or more gain and delay variables of the controller for autopilot and auto-throttle signals including pitch command, roll command, N1/EPR target, airspeed target and vertical speed command in order to ensure that the RNP is met for the aircraft during the different phases of flight and that the autopilot is optimized for its best performance. 
       FIG. 7  illustrates method  700  in accordance with some embodiments of the present invention for providing an iterative control loop for adjusting the autopilot and auto-throttle functions of upgraded FMS  200  during a detection period. Specifically, and as discussed in reference with  FIG. 6 , at  702  upgraded FMS measures the actual performance of the aircraft by monitoring actual flight parameters as discussed above at  602 . The obtained measurements are subsequently stored in MCDUs  280 ,  282  NAV databases for retrieval and/or processing by the AFMC  105 . At  704 , the autopilot is informed of a trajectory for a specific phase of light (e.g., a series of waypoints during cruise flight) using NAV computers  280 ,  282 . This trajectory serves as a reference for the autopilot function and provides the necessary navigation commands to upgraded FMS  200 . At  706 , NAV computers  280 ,  282  compute a projected trajectory based on the measured actual flight parameters that is compared at  708  with the pre-determined trajectory retrieved from NAV databases and provided to the autopilot. If, at  710 , NAV computers  280 ,  282  determine that there is a deviation between the two trajectories (e.g., “YES” at  710 ) then method  700  converts at  712  the deviation signals using MCDUs  280 ,  282  into autopilot control signals and at  714  adjusts the autopilot control signals (e.g., by varying the gain and delay) in order to output a corrected autopilot trajectory at  716 . 
     If, however, at  710 , NAV computers  280 ,  282  determine that there is no deviation between the two trajectories (e.g., “NO” at  710 ) then method  700  uses the pre-determined trajectory obtained from NAV databases for the autopilot function. In some embodiments, method  700  can be performed periodically and in an iterative manner based on flight conditions and/or computing resources in order to provide an optimized autopilot and auto-throttle functionality for upgraded FMS  200 . While there have been shown and described various novel features of the invention as applied to particular embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices, systems and methods described and illustrated, may be made by those skilled in the art without departing from the spirit of the invention. Those skilled in the art will recognize, based on the above disclosure and an understanding therefrom of the teachings of the invention, that the particular hardware and devices that are part of the invention, and the general functionality provided by and incorporated therein, may vary in different embodiments of the invention.