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Abstract not found

Memorandum UCB/ERL M05/22 Earlier versions: • UCB/ERL M04/16 UCB/ERL M03/28 UCB/ERL M02/23 UCB/ERL M99/40 UCB/ERL M01/12

matthew.j.daigle, indranil.roychoudhury, gautam.biswas,

Complex control systems are heterogeneous, in the sense of discrete computer-based controllers interacting with continuous physical plants, regular data sampling interleaving with irregular communication and user interaction, and multilayer and multimode control laws. This heterogeneity imposes great challenges for control system design in terms of end-to-end control performance modeling and simulation, traceable refinements from algorithms to software/hardware implementation, and component reuse. This paper presents an actor-oriented design methodology that tackles these issues by separating the data-centric computational components (a.k.a. actors) and the controlflow-centric scheduling and activation mechanisms (a.k.a. frameworks). Semantically different frameworks are composed hierarchically to manage heterogeneous models and achieve actor and framework reuse. We introduce a notion of responsible frameworks to characterize the property that a framework can aggregate individual actor’s execution into a well-defined composite execution such that heterogeneous models can be composed. This methodology is implemented in the Ptolemy II software environment. We discuss how some of the most useful models for control system design are implemented as responsible frameworks. As an example, the methodology and the Ptolemy II software environment is applied to the design of a distributed, real-time software implementation of a pendulum inversion and stabilization system.

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Many modeling techniques for embedded systems focus on events that occur in time and the causality relationships between them. Event-oriented modeling complements classoriented, object-oriented, actor-oriented and state-oriented approaches. To facilitate event-oriented modeling, we have extended an older established model called event graphs to define new model of computation that we call Ptera (Ptolemy event relationship actors). Ptera is appropriate for modeling complex discrete-event systems. A key capability is that Ptera models conform with an actor abstract semantics that permits hierarchical composition with other models of computation such as discrete-event actors, dataflow, process networks and finite state machines. This enables their use in complex system design, where not every aspect of the system is best described with event-oriented modeling. Categories and Subject Descriptors C.3 [Special-Purpose and Application-Based Systems]: real-time and embedded systems; F.1.1 [Computation by