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Introduction
- Sylvain Ménard
Page Content
- 1 Overview
- 1.1 Features
- 2 RTE Data Type
Overview
RT-EVENTS is a Simulink blockset for fixed-time-step simulation of hybrid systems involving dynamics and discrete events asynchronous with respect to the simulation clock. As RT-EVENTS is designed for and works with fixed step size, it is therefore compatible with Simulink Coder and RT-LAB, and is usually used for real-time simulation and control.
The RT-EVENTS blockset is the solution to the following problems encountered in the simulation of event-based systems.
Problem 1: Very long simulation time | The simulation time of mixed-mode (event-triggered/discrete/continuous) is increasing drastically with system complexity and the number of discrete events involved in the simulations. This kind of simulations traditionally requires time-consuming variable step-solver. The actual visual simulation tools are limited to code generators that do not support variable-step algorithms, and are also limited to run in interpretative mode on a single CPU. |
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Problem 2: Imprecise hard-real-time simulation | Time-consuming variable time solvers are usually required to compensate for errors introduced by events occurring between two-time samples. This technique cannot be applied for hard real-time applications requiring fixed time-step solvers. The actual discrete simulation algorithms suffer from intrinsic limitations. They introduce errors in the solutions of mixed-mode systems when events occur between the sampling instants and they require sampling periods and/or interrupt response latencies smaller than the specified timing precision of critical events; for example, 10µs for a combustion engine. Models with sampling periods smaller than 10 µs are not practical with actual commercial processors and I/O technologies. |
Features
The problems described above justify the use of the RT-EVENTS blockset.
Here are the major features of the RT-EVENTS blockset:
RT-EVENTS blockset allows precise simulation of event-based or mixed-mode systems by compensating for the errors introduced by events occurring between the sampling instants. The precision obtained with the RT-EVENTS blocks depends on the step size selected with respect to the frequency content of the signals involved.
RT-EVENTS blockset also allows fast simulation of event-based or mixed-mode systems. The use of a fixed step size renders the RT-EVENTS blocks suitable for hard real-time simulations and are faster simulations than those performed with variable step algorithms. The RT-EVENTS blockset is also adaptable to distributed real-time simulations with RT-LAB.
RT-EVENTS is, of course, compatible with Simulink and with Simulink Coder code generator.
RTE Data Type
RT-EVENTS supports two signal data types: RTE Boolean and RTE Double (See RTE Conversion - Description for more information about those types). They are used to storing respectively the values of boolean and double discrete signals. In both cases, the change in the value can occur during a calculation step.
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