Modeling of Hierarchical Multi-Modal Systems in Ptolemy II
Dr. T. John Koo, UC Berkeley

In a multi-modal control paradigm, high level tasks are accomplished by appropriately switching between the low-level control modes. Each control mode corresponds to a controller which is designed for a different set of outputs in order to meet the given performance objectives and system constraints. In terms of formal modeling framework, the multi-modal control system can be modeled as a hierarchical nesting of parallel and serial composition of discrete and continuous components. At each level of the hierarchy, a model of computation governs the behaviors and interactions of components. Ptolemy II is a system-level design tool that supports the formal integration of multiple models of computation. An example of hierachical multi-modal system, based on a helicopter to achieve high-altitude takeoff task from a hover mode, is modeled in PtolemyII.