D. Stewart and P. Khosla, "The chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects," International Journal of Software Engineering and Knowledge Engineering, vol. 6, no. 2, pp. 249--277, 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....power in fact their capabilities are largely limited by our ability to produce the software needed to correctly couple perception to action. The (as yet) strongly experimental nature of robotic systems engineering places a strong emphasis on rapid prototyping and software reusability [1, 2]. To put it another way, experience suggests that effective robot software construction is an incremental process of development, testing, and refinement. Thus, a good development environment should allow a user to pull standard tools (e.g. wall followers, control algorithms, and so forth) off ....

....level of robotic system software. Tasks provide a level of abstraction for defining more complex algorithms. These notions can be further specialized into abstractions which correspond to specific architectural styles such as the subsumption architecture [11] motor schemas [8] port based agents [1], or the previously cited process model of Lyons [7] Frob, in and of itself, makes no commitment to a specific style of programming or system architecture. In fact, it is usually straightforward define an architecture or style of programming within Frob. For example, three fundamental notions in ....

D. Stewart and P. Khosla, "The chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects," International Journal of Software Engineering and Knowledge Engineering, vol. 6, no. 2, pp. 249--277, 1996.

.... the development of robot programming systems has been an area of active research in robotics (see [2] for a recent collection of articles in this area) Many of these languages are realized by defining data structures and certain specialized library routines to existing languages (notably C [6, 5, 10, 16], Lisp [1] Pascal [11] and Basic [15] In particular, most of these languages include special functions or commands that operate in the time domain. For example, VAL includes a command to move the robot to a given spatial location. This command operates asynchronously and has, thereby, the ....

....given spatial location. This command operates asynchronously and has, thereby, the side effect of stitching together multiple motions if they are supplied in rapid order. Likewise, other embedded languages such as the Behavior Language of Brooks [1] and the Reactive Control Framework of Khosla [16] provide rich programming environments for the coordination of time domain processes. AML [17] is an exceptional case it is a language designed from scratch. As such, it supplies similar capabilities to VAL, but with the addition of enhanced error handling capabilities for robot program ....

D.B. Stewart and P.K. Khosla. The chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects. International Journal of Software Engineering and Knowledge Engineering, 6(2):249--277, 1996.

....been developed at CMU [14] 15] It was mainly addressed to achieve recon gurability and software reutilization for real time systems, concretely, a recon gurable robotic arm. It de nes a software component, the port object, relies on services of a speci c real time operating system, Chimera [16] [17], for software assembly, and was designed for a particular hardware set: real time processing units and VME buses. The work presented in this paper pursuits has also de ned a software component based on port automata theory, but there are no assumptions about a speci c operating system with a ....

D.B. Stewart and P. Khosla. The Chimera Methodology: Designing Dynamically Recongurable and Reusable Real-Time Software using Port-Based Objects. International Journal of Software Engineering and Knowledge Engineering, 6(2):249-277, June 1996.

....absence of a definition, we will present the attributes we feel are important. Input output relationship. Agents must do something within their world, whether that world is real or simulated. They must also be responsive to that world or, at least parametrizable. Our model of port based objects (Stewart and Khosla, 1996) allows agents to possess both input output ports and resource ports. Input output ports are considered variables during run time, while resource ports are considered variables during initialization. In either case the ports are inputs and outputs to which the agent responds or effects its ....

Stewart, D.B. and P.K. Khosla, 1996, "The Chimera Methodology: Designing Dynamically Reconfigurable and Reusable RealTime Software Using Port-Based Objects," International Journal of Software Engineering and Knowledge Engineering, v. 6, n. 2, pp. 249-277.

....widely available. As a result, developing flexible, robust robotic systems is rapidly being reduced to a problem of effective software engineering. In particular, the (as yet) experimental nature of building robotic systems places a strong emphasis on rapid prototyping and software resusability [17, 12] It is well known that the defining quality of any software development environment is its ability to capture the abstractions needed in its domain. Following [6] we can think of robotic software systems consisting of three general categories of algorithms: lowlevel control (sometimes called the ....

....level of robotics systems software. Events and processes support development at the second level. At the highest level, we are interested in developing abstractions which correspond to specific architectural styles such as the subsumption architecture [3] motor schemas [2] port based agents [17], or the previously cited process model of Lyons [15] Frob, in and of itself, makes no commitment to a specific style of programming or system architecture. In fact, it is usually straightforward define an architecture or style of programming within Frob. The advantages of using Frob to define ....

D.B. Stewart and P.K. Khosla. The chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects. International Journal of Software Engineering and Knowledge Engineering, 6(2):249--277, 1996.

....execution platforms. Since we enable customizations at the source code level it is also worth to compare to current research in software synthesis. The Chimera project proposes to build realtime software by interconnecting components that follow the paradigm of Port Based Objects[13]. In contrast to Dreams the Chimera methodology depends on a noncustomizable kernel that supports this type of objects. Ptolemy[11] is able to generate code from multiple programming paradigms like dynamic data flow. Code generation targets exist for hardware synthesis systems, native assembler ....

D. B. Stewart and P. Khosla. Chimera methodology: designing dynamically reconfigurable real-time software using port-based objects. In Workshop on Object-Oriented Real-Time Dependable Systems (WORDS), Piscataway, NJ, USA., pages 46--53. IEEE, 1995.

....to j . Figure 3 gives an example of a task graph. The task graph model incorporates many essential features such as task sharing, simple synchronization, software reusability, and network transparent communication. Several researchers have proposed similar models for distributed control systems [9, 15]. The properties of the task graph model are as follows: 1) A real time system is composed of a set of communicating tasks. Tasks perform the computational activities in the system which consists of reading data from all its input ports, operating on the data, and finally, writing data to its ....

....Search Harmonicity and Range Constraints Deadline Assignment for Message Tasks Phase Variable Elimination Phase Assignment Task Periods, Deadlines, Phases Period Assignment Deadline, Phase Assignment fail fail fail Figure 9: The intermediate constraint solving procedure. 7, 20] 8, 20] 9, 20] [15, 50] 10, 15, 20 10, 15, 20 15, 20, 25, 30, 35, 40, 45, 50 15. 20 30, 40, 45 15, 20 15, 20 15, 20 15, 20 15, 20 Utilization 10, 15, 20 35, 40, 45, 50 Time Granularity Pruning Harmonicity Pruning Pruning T 3 T 4 T 5 T 6 T 3 T 4 T 5 T 6 T 3 T 4 T 5 T 6 T 3 T 4 T 5 T 6 T 3 T ....

D. Stewart and P. Khosla. The Chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects. Intl. Journal of Software Engineering and Knowledge Engineering, 1996. To Appear.

....is just used to tune an existing kernel or if it can be used to synthesize application specific execution platforms. The Chimera project pursues the concept of software synthesis. It proposes to build real time software by interconnecting components that follow the paradigm of Port Based Objects[10]. In contrast to Dreams the Chimera methodology depends on a non customizable kernel that supports this type of objects. 6 Current State and Conclusions In this paper, we have presented the design methodology of the Dreams system that builds a basis for the synthesis of either embedded ....

D. B. Stewart and P. Khosla. Chimera methodology: designing dynamically reconfigurable real-time software using port-based objects. In Workshop on ObjectOriented Real-Time Dependable Systems (WORDS), Proceedings 1995. IEEE, Piscataway, NJ, USA. p 46-53. IEEE, 1995.

....the internal organization of agents, aims to explore recursively composed systems, and exploits selfadaptivity to cope with changing real world operating conditions. The port based concept is derived primarily from portbased objects, first proposed and implemented by Stewart and Khosla in Chimera [6]. Port based objects were designed for real time control applications in a multi processor environment with a single high speed backplane. A link between two objects is created by connecting an output port of one object to a corresponding input port of another object. The informational scope ....

Stewart, D.B and P.K. Khosla. "The Chimera Methodology: Designing Dynamically Reconfigurable and Reusable Real-Time Software Using PortBased Objects", International Journal of Software Engineering and Knowledge Engineering, v. 6, n. 2, pp. 249 - 277, June 1996.

....internal organization of agents, aims to explore recursively composed systems, and exploits selfadaptivity to cope with changing real world operating conditions. The port based concept is derived primarily from port based objects, first proposed and implemented by Stewart and Khosla in Chimera [6]. Port based objects were designed for real time control applications in a multi processor environment with a single high speed backplane. A link between two objects is created by connecting an output port of one object to a corresponding input port of another object. The informational scope ....

Stewart, D.B. and P.K. Khosla. "The Chimera Methodology: Designing Dynamically Reconfigurable and Reusable Real-Time Software Using Port-Based Objects", International Journal of Software Engineering and Knowledge Engineering, v. 6, n. 2, pp. 249 - 277, June 1996.

....the robots to reactive control schemes. Furthermore, since the controllers for many of these robots were designed in hardware, self adaptation was not feasible. The port based concept is derived primarily from portbased objects, first proposed and implemented by Stewart and Khosla in Chimera [8]. Port based objects were designed for real time control applications in a multiprocessor environment with a single high speed backplane. The informational scope within which the port based objects exist is a flat, public data structure visible to all objects. This implementation is very efficient ....

D. B. Stewart and P. K. Khosla. The chimera methodology: Designing dynamically reconfigurable and reusable real-time software using port-based objects. International Journal of Software Engineering and Knowledge Engineering, 6(2):249--277, 1996.

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Stewart, D.B. and P.K. Khosla, 1996, "The Chimera Methodology: Designing Dynamically Reconfigurable and Reusable Real-Time Software using Port-Based Objects," International Journal of Software Engineering and Knowledge Engineering, v. 6, n. 2, pp. 249-277, June.

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