Abstract:
Methods and apparatus are provided for building and executing reconfigurable algorithms in on-board environments which require pre-certification of the compiled code, such as avionics, flight control, and military applications. The code execution architecture includes a library of reusable function modules in the form of pre-compiled code blocks; an algorithm execution utility (AEU) for processing a user-assembled string of code blocks; and a customer interface for selecting code blocks, defining their associated parameters and sequence (execution order), structuring inputs and outputs, and for providing the integrated, machine readable application to the AEU at run time. The various sequences, permutations and combinations of functions and their associated parameters, inputs and outputs are pre-approved or certified a priori; consequently, the on-board reconfiguration and execution of complex algorithms may be performed in real time without the need for recoding, verification, or redeployment of the code base.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates, generally, to computer based systems for building and executing diagnostic algorithms in environments requiring certification or pre-approval of the algorithm code base, such as avionics, on-board flight control systems, and military applications. More particularly, the invention relates to a modular code execution architecture which is dynamically reconfigurable in the field without the need for re-certification and re-deployment of the code base. 
       BACKGROUND 
       [0002]    Several powerful analyses tools and architectures are currently available in the industry, such as Matlab from Mathworks.com and RapidMiner from Rapidminer.com. Specific architectures have also been developed for particular types of data analyses, such as Honeywell&#39;s IMDS (Integrated Mechanical Diagnostic System) which facilitates analyses related to off-board, condition based maintenance (CBM) programs. These systems monitor critical engine and drive train components, electronic, mechanical, pneumatic, and hydraulic controls, and fatigue life limited structures. 
         [0003]    A key characteristic of these diagnostic systems surrounds their modularity; that is, their underlying code base is composed of separate (discrete) functional modules or blocks of code which, when properly combined at run time, work together as a single, integrated application. This avoids the need for developers to rewrite code for repetitive or recurring functions, such as reading temperature, sensing rotor or driveshaft speed (rpms), sampling airspeed, or the like. 
         [0004]    The ability to reconfigure these tools is particularly useful in off board analyses. In an off board context, the user has time to “try out” various analytical approaches and algorithmic configurations, and often has access to previously captured or recorded data streams. Thus, the user can add, remove, substitute, or augment the various functional modules that make up an application with one or more additional modules, and to reconfigure the inputs to and outputs from the modules (e.g. engine temperature) to redefine the overall functionality of the application. When the reconfigured modules are recombined, the revised application—with its newly defined functionality—is recompiled and executed at run time. 
         [0005]    Conversely, the reconfigurability of on board systems, such as flight control and diagnostic software, has not received much attention. This is primarily because once a product designed for on board deployment is proven to work in its intended environment, i.e. it has been tested and verified, there is little incentive to change the product after deployment. It can be expensive and cumbersome to re-code, retest, verify, recompile, and re-deploy the code base. This is particularly true when the underlying software is subject to certification or pre-approval, such as flight control, avionics, IMDS, and government and military applications. Moreover, in certain applications accessing the code is impractical, such as when a ship is out to sea on an extended mission or its location is secret. 
         [0006]    Accordingly, it is desirable to provide on board diagnostic systems which overcome the foregoing limitations. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention. 
       BRIEF SUMMARY 
       [0007]    On board systems and methods are provided for building and executing diagnostic algorithms of the type requiring pre-certification or pre-approval of the compiled code prior to deployment. The system includes a library of function modules in the form of reusable code blocks, and a processing unit, or algorithm execution utility (AEU), for processing a user assembled string of functions. The system further includes user interface hardware for selecting a set of functions, defining their execution sequence, parameters, inputs, and outputs, and assembling them into a machine readable application which can be fed to the AEU for execution. 
         [0008]    Methods are provided for dynamically configuring algorithms in an on board system which requires certification or approval of the algorithm code base prior to or at the time of deployment. The method includes providing a library of functions and an AEU for executing a string of functions assembled as an algorithm; selecting the string of functions from the library (where one or more of the functions may have an associated parameter having a selectable value); defining the value(s) of any parameters and the sequence for executing the selected functions; structuring inputs and outputs for the string of functions; assembling the function modules, parameter value, indicia of the execution order of the function modules, and the inputs and outputs into a loadable image, referred to herein as a loadable Integrated Reference Model (IRM); and providing the IRM to the AEU for run time execution. The IRM may be a compact, binary file containing data from a database which allows for very fast access at run time, rather than accessing the database directly at run time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
           [0010]      FIG. 1  is a block diagram of an exemplary code execution architecture for building diagnostic algorithms in accordance with the subject matter described herein; 
           [0011]      FIG. 2  illustrates four schematic flow diagrams, each representing an algorithm configured in accordance with exemplary embodiments of the subject matter described herein; 
           [0012]      FIG. 3  is a schematic flow diagram illustrating the equation (y=ax+b) for the specification sheet shown in  FIG. 4 ; 
           [0013]      FIG. 4A  is a table illustrating a specification sheet for the equation implemented by the algorithm shown in  FIG. 3  according to a preferred embodiment; 
           [0014]      FIG. 4B  is a tabular legend for the specification sheet shown in  FIG. 4A ; and 
           [0015]      FIG. 5  is a flow chart illustrating a method for building and executing diagnostic algorithms in accordance with a preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description. 
         [0017]    Those of skill in the art will appreciate that the various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Some of the embodiments and implementations are described above in terms of functional and/or logical block components (or modules) and various processing steps. However, it should be appreciated that such block components (or modules) may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. 
         [0018]    To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. 
         [0019]    For example, an embodiment of a system or a component may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments described herein are merely exemplary implementations. 
         [0020]    The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. 
         [0021]    A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” 
         [0022]    The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. 
         [0023]    In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the invention as long as such an interchange does not contradict the claim language and is not logically nonsensical. 
         [0024]    Furthermore, depending on the context, words such as “connect” or “coupled to” used in describing a relationship between different elements do not imply that a direct physical connection must be made between these elements. For example, two elements may be connected to each other physically, electronically, logically, or in any other manner, through one or more additional elements. 
         [0025]    In one embodiment, the system for building diagnostic algorithms is implemented in an aircraft. In other embodiments, the system may be implemented in a land, marine, or amphibious vehicle. 
         [0026]    Referring now to  FIG. 1 , an architecture  100  for building reconfigurable diagnostic algorithms includes a function library  102 , a loadable diagnostic image (also referred to as an Integrated Reference Model (IRM))  104 , and an Algorithm Execution Unit (AEU)  106 . 
         [0027]    In accordance with a preferred embodiment, function library  102  includes a plurality of reusable, functional modules in the form of discrete blocks of compiled code; that is, they are stored in machine readable format to minimize compiling errors at run time. In this way, the modules may be certified or pre-approved prior to their inclusion in the library. This is particularly important in aviation, government, and military applications where software and other product components must undergo testing and/or verification by an oversight authority such as the Federal Aviation Administration (FAA), National Transportation Safety Board (NTSB), Department of Transportation (DOT), Department of Defense (DOD), or other regulatory agency. 
         [0028]    The functional modules in library  102  may be simple or complex, and may operate on scalar, vector, or combinatorial inputs. Functions may range from simple “add”, “subtract”, “multiply”, or “divide” functions, to more complex trending, regression, fast Fourier transform (FFT), and hierarchical and customizable tasks. Other functions may include analog and digital functions representing low, high, and band pass filters, prognostic and predictive functions, and the like. 
         [0029]    The various functions may also have one or associated parameters which may be defined by the user. For example, the function “low pass filter” may have an associated parameter “filter order” which the user may define to be a first, second, or third order filter. The “low pass filter” function may also have an associated parameter which allows the user to define filter coefficients, for example. The various functions and their associated parameters in library  102  are a priori known and complied as machine readable code prior to inclusion in the library. 
         [0030]    Function library  102 , IRM  104 , and AEU  106  cooperate to implement a reconfigurable, on board, code execution architecture. AEU  106 , by itself, does not “know” which functions to execute, in what order, or how to assign inputs, outputs, and parameters when constructing an algorithm. For this purpose, a user interface (not shown) may be provided including input/output hardware such as a human readable display, keyboard, mouse, toggle, or the like for facilitating user interaction with system architecture  100  to thereby allow the operator to configure the algorithms for execution by AEU  106 . 
         [0031]    With continued reference to  FIG. 1 , an exemplary IRM  104  is illustrated as a data sheet which includes identifies a particular algorithm (e.g., algorithm  1 ), the various functions included in the algorithm, and any inputs, outputs, and parameters associated with the algorithm. In the example shown in  FIG. 1 , the following functions are included in the algorithm: a low pass filter  122 , a regression module  124 , a trending module  126 , and a calculation module  128 . 
         [0032]    Before execution the algorithm, “snapshot” data  108  is captured. These data may include, for example, sensed or target values of various parameters such as temperature, speed, and the like. Snapshot data  108  and IRM data  104  are provided to AEU  106 , whereupon AEU  106  calls the designated functions from library  102 , and executes the algorithm. A local memory  130  may be used for the temporary storage of data and other values and parameters, as needed. AEU  106  provides appropriate output values  132  in accordance with the outputs defined in IRM  104 . 
         [0033]    Referring now to  FIG. 2 , four different exemplary algorithms (algorithms  1 - 4 ) are shown operating on respective inputs M 1  and M 2  to produce respective outputs Y 1  and Y 2 . More particularly, Algorithm  1  illustrates a string of two functions, namely, Function A and Function B, selected from function library  102 . Function A has input ports AI 1  and AI 2  and output ports AO 1  and AO 2 . Similarly, Function B has input ports BI 1  and BI 2 , and output ports BO 1  and BO 2 . Algorithm  1  has been configured such that input M 1  is applied to input port AI 1  of Function A, and input M 2  is applied to input port AI 2  of Function A. Algorithm  1  is also configured such that output Y 1  is output from port BO 1  of Function B, and output Y 2  is produced by output port BO 2  of Function B. 
         [0034]    With continued reference to  FIG. 2 , Algorithm  2  is similar to Algorithm  1  except that the external inputs are switched; that is, in Algorithm  2  input M 2  is applied to input port All of Function A, and input M 1  is applied to input port AI 2  of Function A. Hence, the two algorithms (namely, Algorithm  1  and Algorithm  2 ) will produce different outputs. This highlights the dynamic reconfigurability of system  100  in that Algorithm  2  may be constructed from Algorithm  1  by simply switching inputs M 1  and M 2  from respective input ports AI 1  and AI 2 , in the first instance (Algorithm  1 ), to respective input ports AI 2  and AI 1  in the second instance (Algorithm  2 ). This also highlights the ease by which the user may construct a new, stand alone algorithm from a previous algorithm. 
         [0035]    In an analogous manner, Algorithm  3  may be conveniently constructed by reconfiguring Algorithm  1  to apply the output from port AO 1  to port BI 2  (instead of port BI 1 ), and to apply the output from port AO 2  to port BI 1  (rather than port BI 2 ). Similarly, Algorithm  4  may be constructed from Algorithm  1  in the following manner: substituting Function G for Function A; appending Function C to Function B; and applying the outputs of Function B to the input ports of Function C. 
         [0036]    Referring now to  FIGS. 3 and 4 , a block flow diagram and associated specification sheet are set forth for implementing the algorithm “y=ax+b”. With particular reference to  FIG. 3 , Functions J and K are selected from library  102  and strung together to build an exemplary Algorithm “n”. In the illustrated example, Function J represents the mathematical operator “Multiply” and is assigned evaluation order number one. Function K represents the mathematical operator “Add” and is assigned evaluation order number two. Inputs M 1  and M 2  are applied to input ports JI 1  and JI 2 , respectively, of Function J. Output port JO 1  of Function J is connected to input port KI 1  of Function K (to thereby apply the output from port JO 1  to port KI 1 ), and input M 3  is applied to input port KI 2  of Function K. 
         [0037]    With continued reference to  FIGS. 3 and 4 , parameters “a” and “x” are assigned to inputs M 1  and M 2 , respectively, and parameter “b” is assigned to input M 3 . When the specification sheet shown in  FIG. 4A  is applied to AEU  106  at run time, Algorithm “n” produces the value (parameter) “y”, assigned to output Y 1 , in the equation “y=ax+b” as follows: i) Function J is initially executed to multiply input M 1  by input M 2  to yield the product “ax” identified as variable “temp”; ii) Function K is then executed to add input M 3  (“b”) to the value “temp” (“ax”); and iii) the sum “ax+b” is output from Function K, expressed as variable “y”; and iv) the variable “temp” is discarded at the end of execution since it is not used. 
         [0038]    Referring to  FIG. 5 , a method  500  for building and executing diagnostic algorithms in accordance with an embodiment includes providing a library of function modules (task  504 ), and compiling the library and Algorithm Execution Unit (AEU)  106  as one application (task  506 ). The code base, including the executable application and its associated IRM  104 , may then be deployed (task  508 ). At runtime, snapshot data  108  are measured (task  510 ) and recognized by AEU  106  (task  512 ). 
         [0039]    With continued reference to  FIG. 5 , it will be appreciated that prior to code deployment, the function modules and their execution order are selected by the operator (task  514 ) as discussed above. In similar fashion, the operator defines the inputs, outputs, and any temporary variables for the functions, as needed (task  516 ). This information is used to construct IRM  104  (task  518 ). AEU  106  then executes the modules associated with the measured inputs (task  520 ). 
         [0040]    While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.