Abstract:
An apparatus used as a platform for developing embedded real-time software for controlling fault tolerant opto-electro-mechanical systems. The platform provides a portable model-based design environment conducive to validation and verification of the Control Laws and of the Plant model. The platform is also useful for observing the overall system behavior by injecting faults or failures which can be destructive, expensive or difficult if applied to the real system. The platform is comprised of multiplicities of serial data ports, serial port converters, single board microcontrollers, and external interfaces. The apparatus includes at least one interface board that cross connects at least two microcontrollers and allows the downloading of the Plant and Control algorithms to each microcontroller through available serial interfaces enabling evaluation of the modeled system behavior. The apparatus includes an embedded software development tool-chain facilitating an order of magnitude increase in embedded software development productivity.

Description:
TECHNICAL FIELD 
     Certain embodiments of the present disclosure generally relates to embedded systems and, more particularly, to the filed of realtime control 
     BACKGROUND 
     The software industry has seen some dramatic changes from the early days of computer technology development. Until the early 1980&#39;s computer software was written manually and the design process was ad-hoc. In the 1980s, Yordon and Demarco introduced Structured SW Design Methodology. The techniques were a powerful method based on the divide and conquer concept. The structured design methodology paved the way to automatic code generation. 
     In 1989, Lary LEHMAN, et al of Integrated Systems Incorporated (U.S. Pat. No. 4,796,179) entitled: Multirate real time control system code generator which is an application software for graphical programming. At the same time, under the leadership of Haik BIGLARI a group of SW engineers in the Boeing company began to undertake the task of automating code generation, in a project called, “Application Generator” [4]. 
     Development of any intelligent system is a multi-disciplinary activity. Due to the complexities and natural evolution of these disciplines, the corresponding domain experts have developed their own methods of communication. As a result, there is a communication gap between these disciplines, which gives rise to significant loss of productivity. Although the automatic code generation has increased the productivity of the programmer, still the gap between different disciplines remained wide. 
     In the early 2000, rapid prototyping with automatic code generation attempted to narrow the gap. In 2001, Kodosky et al, (U.S. Pat. No. 6,173,438) disclose: Embedded Graphical Programming System. In 2006, Mike Santori (U.S. Pat. No. 7,076,740) discloses a patent titled: System and Method for Performing Rapid Control Prototyping Using a Plurality of Graphical Programs that Share a Single Graphical User Interface. In 2007, Borg et al. (U.S. Pat. No. 7,197,743) disclose: Methods for Generating Computer Software for Embedded Systems. In 2009, Kodosky et al, (U.S. Pat. No. 7,558,711) disclose: Generating Hardware Description of a Block Diagram Model Implementation on a Programmable Hardware. 
     SUMMARY OF THE INVENTION 
     The primary object of the invention is to provide a cost effective rapid prototyping environment for System Engineering analysis and Software development. 
     Another object of the invention is to provide an environment for multiple engineering disciplines to collaborate on the same platform. 
     Another object of the invention is to narrow the gap between software engineers, hardware engineers and systems engineers. 
     A further object of the invention is to help identify software or system problems early in the development life cycle. 
     Yet another object of the invention is to support conventional as well as model based design methodology. 
     Still yet another object of the invention, is that the invention naturally lends itself to Automatic Code Generation. 
     Another object of the invention, is that the invention improves software maintainability. 
     Another object of the invention, is that the invention increases the efficiency associated with embedded software testing. 
     A further object of the invention, is that the invention can identify discrepancies in requirements early in the software development life cycle. 
     Yet another object of the invention, is that the invention facilitates transfer of the developed software to the target processor. 
     Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. 
     In accordance with a preferred embodiment of the invention, there is disclosed a Platform for Developing Embedded Software comprising: A laptop or a Personal Computer with printer port, two USB (Universal Serial Bus) to CANbus (Control Area Network Bus) converters, One USB to RS-232 converter, two single board microcontrollers, interface board interfacing the two microcontrollers, and software development tool chain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. There are total of 10 drawings, each illustrating an aspect of the invention. The drawings are not drawn to scale to better emphasize the component under consideration. The Present invention houses multiplicity of microcontrollers and the interconnecting interfaces. 
         FIG. 1  illustrates an example of realtime software development environment in accordance with certain embodiment of the present disclosure. 
         FIG. 2  illustrates various processes which may be utilized in realtime embedded software development in accordance with certain embodiment of the present disclosure. 
         FIG. 3  illustrates the exploded view of the Embedded Software Development Platform in accordance with certain embodiment of the present disclosure. 
         FIG. 4  illustrates an example Graphical User Interface that may be used with certain embodiment of the present disclosure. 
         FIG. 5  illustrates a partial block diagram of the overall system development environment, in accordance with certain embodiment of the present disclosure. 
         FIG. 6  illustrates an example of a typical application known as Magnetic Levitation System implemented in accordance with certain embodiment of the present disclosure. 
         FIG. 7  illustrates an aspect of graphical user interface pertaining to the system response of the typical application shown in  FIG. 6 . 
         FIG. 8  illustrates major components and their interconnections in accordance with certain embodiment of the present disclosure. 
         FIG. 9  illustrates a USB based relay that can be used to reset the operation the Embedded Software Development Platform (ESDP) in accordance with certain embodiment of the present disclosure. 
         FIG. 10  illustrates the interaction of three disciplines via a common ESDP in accordance with certain embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather, as a basis for the claims and as a representative basis for teaching one skilled in the art, to employ the present invention in virtually any appropriately detailed system, structure or manner. 
     Turning first to  FIG. 1 , the figure captures the embedded software development environment  100 , which includes an Embedded System Development Platform (ESDP)  105 . A laptop  101  with a rapid software development tool-chain. It also includes, multiplicity of interface converters for USB as a potential interface among others. For instance CAN/USB converter  103  may be connected to LAPTOP  101  via a USB cable  102 . The other side of the converter  103  may be connected to ESDP  105  to provide information in regards to the evolution of the plant model residing in the ESDP  105  via CANbus  104  for the user station at LAPTOP  101 . 
     In addition, information in regards to the evolution of the controller model residing in ESDP  105  may be transmitted via CANbus  111  to CAN/USB converter  110  via USB cable  109  to the user located at LAPTOP  101 . 
     Furthermore, the user located at the station  101  may communicate with the controller residing in ESDP  105  during its operation via a separate channel. For instance this channel could be an RS232 interface. In station  101  if RS-232 is available then it me directly interface with ESDP  105 . If station  101  is equipped with USB, then standard RS232 converter  107  can be utilized which uses USB cable  108  and RS232 cable  106 . 
     Turning to  FIG. 2 , the figure illustrates a Model Based Design (MDB) approach  200  which may be utilized with certain embodiment of the present disclosure. The operation of this approach begins with the development of the overall system model and ends with the generation of the executable code for the target processor. 
     The process begins at the START  201 . Based on the requirements of the plant portion of the system, the user of ESDP  105  finds an algorithmic representation of the plant  202 . The algorithmic representation may be combination of algebraic equation, linear or non linear differential equations, and/or may be described by a set of linear or non linear difference equations. Alternatively, the plant model  202  may be described by a quintuple. 
     To validate and verify the plant model  202 , it may be simulated on a digital computer  203 . 
     To regulate or control the plant, the user finds an algorithmic representation of the controller which is commonly known as the control law  204 . 
     The user then integrates the control law  204  with the plant model  202 , to obtain the overall system which is simulated on a digital computer  205 . 
     The process flow continues via bubbles  206  and  207  to the decision block  208  where the user examines the system response to see if it meets the system requirements. If the requirements are not met then the user goes back to block  202 . 
     If the requirement are met, the plant model is converted to run in realtime  209  which may use the plant portion of ESDP  105 . 
     Similarly, the controller model is converted to run in realtime  210  which may use the controller portion of ESDP  105 . 
     With the aid of appropriate set of tool chain, the user generates realtime Executable Object Code (EOC) for the controller and the plan  211 . 
     The process continues via bubbles  212  and  213 . The user then down downloads the EOC  214 . The controller gets downloaded into the controller portion of the ESDP  105  via CANbus  104  and the plant model gets downloaded into the plant portion of ESDP  105  via CANbus  111 . 
     The response of the realtime system simulation is verified and validated against the overall system requirements in the decision block  215 . If the requirements are not met then the user goes to block  209 . 
     If the system requirements are met, then the EOC is ported to the target Controller  216 . 
     The system including hardware and software is tested in  217  and the process ends at  218 . 
     Turning now to the drawing in  FIG. 3 , the drawing shows the exploded view of the ESDP  300 . As it can be seen, typical ESDP has an enclosure which is composed of a top cover  301  and a bottom cover  311 . 
     Two single board microcontrollers ( 302 ,  304 ) and interface board  303  are designed to be interconnected according to  FIG. 8 . One of the microcontrollers is used to execute the controller model, while the other is used to execute the plant model. The number of microcontrollers are not limited to two, but it establishes the minimum set needed for adequate modeling. 
     The top cover  301  is has multiplicity of slits  313  to allow air cooling of the electronic components. 
     The front  305  and the back  312  have multiplicity of circular holes  310  for mounting multiplicity of light emitting diodes which show the status of the controller and the plant. 
     The front  305  and the back  312  have multiplicity of openings ( 306 ,  307 ,  308  and  309 ) for mounting the interface connectors for the CANbus ( 104 ,  111 ) and RS232 connector  106  respectively. 
     In accordance with the present invention,  FIG. 4 , illustrates the Graphical User Interface  400  which is hosted on a computing platform such as a laptop or PC with screen  401  and keyboard  410 . It provides means to interact with ESDP  105  and evaluate the performance of the implemented algorithm in the plant and the controller in real-time. 
     The screen is partitioned into multiplicity of segments. For instance, segment  402 , may be used for injecting faults on the plant model  509 , Segment  403  may be used to monitor the plant states and segment  404  may be used to monitor and/or alter the controller states. 
     Another segment of the screen may be used for data logging  405  via ( 407 ,  408  and  409 ). The logged data may be used for post mortem analysis. 
     Saved scenarios via the data logging  405  may be reused via  406  to automate the testing process. 
     In accordance with the present invention,  FIG. 5  depicts a block diagram of the over all developmental environment  500 . The environment provides means for real-time Hardware-In-the-Loop (HIL) simulation. Furthermore, the environment also provides means for real-time Software-In-the-Loop (SIL) simulation. 
     The detail features of Graphical User Interface (GUI)  501 , is provided in  FIG. 4 . It interface with the ESDP  502 , via multiplicity of CANbus cables ( 510 ,  512 ) and multiplicity of RS232 cables ( 511 ,  513 ). These cables provide hardware means to transmit the ESDP states to the GUI and allow the user to download EOC and influence the evolution of the EOC during execution. 
     Two EOCs are developed in the GUI. The first EOC is downloaded in the Controller processor  504  and the second EOC is downloaded in plant model processor  509 . 
     The interface board  506  conditions the signal for processors  504  and  509  and provides means for external interfacing with system under control  503 . Internal interfacing is accomplished by  505  and  508 . 
     The external interface  507  can be a mixture of analog or digital signals as needed. 
     To accomplish an important function of the invention, it becomes necessary to simulate in real-time, both the plant and the controller in a single microcontroller. An example of this functionality is shown in  FIG. 6 . It also becomes necessary to display the simulation results in real-time. That functionality is shown in  FIG. 7 . 
     To provide a clear understanding of the invention and its variations, this inventions takes advantage of the recent development in microcontroller technology. Thereby, the size and weight of the control system prototyping is significantly reduced. The key to understanding of this inventions is the principle of duality that exists between controller and the plant. Based on this duality, a plant model may be executed in a microcontroller. There is only one problem with this scheme, the result of the execution must emulate real world signals, which are normally digital and analog type signals. 
     Present day microcontrollers do provide digital signals, but do not provide analog signals. To solve this problem, several techniques may be utilized. One approach is to use a Pulse Width Modulation followed by a low pass filter. Although this method is very inexpensive, it has three drawbacks. First, it is not very accurate. Second, it is very slow. Third, it uses too many digital channels. The accuracy issue can be addressed by providing a feedback and ensure that the desired analog value has been achieved. However, the second and third issue will remain unresolved. 
     The present invention resolves all of the three issues by utilizing a Serial Peripheral Interface (SPI) to analog converter as shown in  FIG. 8 . Interface board  506  is used to mount the required converters and signal conditioners. 
     To further reduce the size, weight and volume, any functionality that can be performed by a laptop, such as editing, compiling, and graphical user interfaces are not duplicated on the platform. 
     Due to the fact that current laptops no longer offer multiple types of interfaces, appropriate converters and their drivers will be needed. Fortunately, these types of converters are available commercially in the market. For instance, commercial RS232 to USB, and CANbus to USB converters are readily available. These converters have very little or no impact on the portability of this invention. 
     What makes the microcontrollers attractive for development of control laws targeted for embedded systems, is the fact that microcontrollers are designed to support multiple input/output (I/O) interfaces. The alternative is to use a microprocessor or Field programmable Gate Arrays (FPGA) with external I/O interfaces as suggested in [1] and [2]. These systems typically require a large number of I/O interfaces, and therefore will increase the size, weight, volume and cost and can no longer be carried in a briefcase. The present invention provides a much larger I/O capability with substantially smaller size, weight, volume and cost. 
     In an alternative implementation, multiple microcontrollers may be plugged into the same backplane, increasing the I/O capabilities by many folds. 
     The present invention can be used in conjunction with the Real-Time Workshop® automatic code generator. Alternatively, the present invention may be used in conjunction with any other manual or automatics code generators, such as LabView® or VisSim® which support the targeted microcontroller. In the preferred embodiment, Real-Time Workshop® with MPC555 microcontroller. The example shown here use the preferred embodiment. 
     The present invention can be easily built by utilizing two Phycore evaluation modules for MPC555 from Phytec, and an interface board shown in  FIG. 8 . All other signals from controller to the plant can be connected directly. 
     Reference [3] should be consulted for SPI drivers and software utilities. MPC555 is a representative core processor and other processors can also provide the equivalent functionalities. 
     Although the example system provided in  FIG. 6  is a Single Input Single Output (SISO), the present inventions is well suited for Multiple Input Multiple Output (MIMO) systems as well. In fact, the present invention is suitable for every phase of embedded software development life cycle. For instance, it can be used during Systems Analysis and Design phase, during requirement definition phase, during software design phase, during software implementation phase, during software testing phase and during system testing phase. 
     Since the present invention supports Hardware-In the Loop (HIL) and Software-In the Loop testing, the platform can be used to take credit for DO-178B or DO-178C certification of Safety Critical Systems. Furthermore, it is possible to use the present invention, and test some aspect of the system that may be destructive or impossible to test, if it were to be performed on the actual system. 
     The benefits of rapid prototyping and model-based design is well understood in the field of real-time control algorithm development. Many graphical programming tools are available commercially, which facilitate rapid prototyping and model based design. For instance MATLAB is used extensively for model-based embedded software development and analysis. MATLAB also supports a large number of microcontrollers, microprocessors, and variety of I/O boards from many different manufacturers. There are also real-time platforms in the market which facilitate real-time embedded software development. 
     The real-time software platforms fail to provide realistic information about data latency and quantization effects, hardware platforms do provide this type of information, but they are not easily portable. Furthermore, due to large number of components they tend to be very heavy and expensive. 
     The present invention takes advantage of the duality between the controller and the plant. Under this duality, if the controller can be executed in a microcontroller, so is the plant. By invoking the duality principle, a large number of I/O capabilities built for microcontrollers can also be used for the plant model, which results in reduced size, weight, volume, and cost of a real-time platform for embedded system development. 
     To further reduce the cost of ESDP, the redundant functionality between the platform and laptop is removed from the ESDP. This includes display functionality and hosting the tool chain for the software development and testing. 
     The apparatus as described in this invention, is modular. A single microcontroller can be used for executing the real-time plant model, while a multiplicity of distinctively different microcontrollers can serve as target controllers. The converse also applies, that is, a single microcontroller can be used as the target controller while a multiplicity of microcontrollers can serve as the plant models.
         In the preferred embodiment, the software tool chain includes but is not limited to:   1) MATLAB and Simulink for algorithm development   2) Real-Time Workshop for automatic code generation   3) LabView or Simulink for monitoring the system behavior   4) Visual Studio for compiling C program   5) TestBed from LDRA for Structural Coverage Analysis   6) Metowerks Codewarrior used as cross-compiler   7) Downloader running on the Laptop or PC   8) Bootcode used for the microcontrollers   9) USB to CANbus converter software   10) USB to RS232 to Converter software   11) USB based relay software for resetting the platform apparatus       

     Similar to prior art, five to ten fold software productivity gain is expected for the apparatus described in this invention, while the size, weight, volume, and cost, are substantially smaller. In fact, the present invention can easily fit in a brief case, and it become, feasible for every software engineer, who develops real-time software for embedded control systems, to have one or multiple ESDP on their desk. 
     Furthermore, due to its reduced cost, system engineers and test engineers also, can have their very own ESDP. Therefore, the ESDP can be used as a common platform among diverse engineering disciplines, and thereby will provide additional productivity over and above what is provided by prior art. 
     When the EDSP is used for testing the system under development, the USB based relay  903  may be controlled from a set of test scripts and automate the entire testing process (see  FIG. 9 ). In that application, ESDP can be reset by the laptop via USB interface  902  whenever the controller enters a shutdown mode. 
     The ESDP  907  is energized/de-energized when the power supply  905  and its cable  904  are disconnected from power  908  via the USB driven relay  903   
     Turning to  FIG. 10 , when the ESDP is used by systems engineers  1003 , they will be able to interact with the system and examine different aspects of system operations and revise the system specification accordingly. For instance, they can inject faults or cause certain component of the system to fail, and see how this fault is detected by the controller and provide feedback to the software engineer via  1002 . Alternatively, they may want to use the ESDP to formulate a strategy for diagnostic or prognostic of the system under development. Therefore, the systems engineer, not only gains a better understanding of the control laws, but also is able to study the behavior of the plant. 
     As the system testing progresses by the test engineer  1005 , he will be able to provide independent feedback to the software engineer  1001  via  1006 , and to the system engineer via  1004 . The methodology lends itself nicely to discover the bugs early in the development phase, which has been proven to reduce the overall development cost considerably. It is entirely possible for all three tasks to be performed by a single person, who is versed in all three disciplines and the man power resources are limited. 
     Clearly, the advantage of the present invention is a common platform which facilitates better communication among all stakeholders of the system to be developed. A better communication leads to higher efficiency and productivity. 
     The apparatus presented in the present invention is a hardware platform, along with a set of software and additional auxiliary hardware, which provides an environment for cost effective development of embedded systems. 
     While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention, as defined by the appended claims.