This paper presents an object-oriented software tool, called RTSIM, aimed at simulating real-time embedded controllers. The tool consists of a collection of C++ libraries permitting a separate specification of the functional behaviour of the controller and of the hardware/software architecture to be used for its deployment. In particular, it is possible to provide an accurate modelling of the concurrent architecture of the control tasks and of the run-time support offered by the operating system for the real-time scheduling of the shared resources (CPU, memory buffers and network links). In this way, it is possible to compare different scheduling solutions by evaluating their simulated performance directly in the domain of the control application. Moreover, the tool can be utilized to tune up design parameters such as the activation frequencies of the tasks. The application of the tool is shown in a meaningful case study.The integration of flows of data from heterogenous sensors, having different requirements in terms of sampling rates and computation times, almost naturally induces concurrent implementation schemes. The ability of the system designer to specify, manage, and verify the functionality and performance of real-time concurrent processes (tasks) turns out to be a crucial success factor. Moreover, in the design of mass-produced embedded systems, the choice of hardware has a strong influence on the economy of the solution. Therefore, even in front of increasingly complex problems, the push towards minimization of computing hardware cost remains a dominant factor. In this context, an increasing emphasis is put on the effectiveness and on the efficiency of the production process of real-time software. Traditional development cycles tend to 'rigidly' separate the work of control engineers from that of software engineers, but the final outcome is often far from optimal in terms of performance/cost criteria.In order to introduce a profound innovation in this field, the availability of co-design tools spanning diverse engineering disciplines is of utmost importance.This paper focuses on one of the most familiar problems in real-time control software design, i.e. how the performance of a controller is affected by architectural and implementation choices (e.g. the decomposition of feedback controllers into tasks, the allocation of computation resources to tasks, the scheduling of the shared resources, etc.). Realistic and quantitative answers to this question during the early phases of the development are precious tools for product development.The concept of performance evaluation for a real-time controller can be developed along different directions. Most of the research in the area of real-time computing has studied the performance of concurrent software systems under the viewpoint of their timing behaviour. Ever since the seminal work of Liu and Layland [1], a fundamental performance metric is considered to be the tasks' schedulability, i.e. the ability for a set of tasks to execute respecting their assigned ...

No abstract

No abstract

No abstract

No abstract