RT-Events is a Simulink toolbox for the fixed-time-step simulation of hybrid systems involving dynamics and discrete events asynchronous with respect to the simulation clock. As the RT-Events Blockset works with a fixed step size, it is therefore compatible with the Real Time Workshop (RTW) and RT-LAB and can be used for real-time applications.
Improved accuracy for discrete simulation of event-based systems
- Compensates for the errors introduced when events occur between samples
- Accuracy depends on the time step selected with respect to the frequency content of continuous signals
Fast simulation of event-driven systems
- No iteration, uses fixed time-step algorithm
- Faster simulation than variable-step algorithms
- Supports distributed real-time simulation
- Suitable for hard real-time applications such as hardware-in-the-loop or embedded simulations
- Compatible with visual simulation tools (e.g. Simulink) and code generators (e.g. RTW)
Using RT-EVENTS
The RT-Events Blockset is the solution to the following problems encountered in the simulation of event-based systems:
Very long simulation time
- The simulation of event-based systems require time consuming variable-step algorithms : Limitations of actual visual simulation tools (e.g. Simulink) :
- Code generators do not support variable-step algorithms
- Simulation tools run in interpretative mode on a single CPU
- Large scale and very complex models with several hundreds of diagrams for typical case
Imprecise hard-real-time simulation
- Variable time step algorithms cannot be used for hard real-time simulations
- Limitations of discrete simulation algorithms
- Errors for event-based systems when events occur between the sampling instants
- Require sampling periods and/or interrupt response latencies smaller than the specified timing precision of critical events; for example, 10s for a combustion engineer
Typical Applications
- Increasing the simulation speed of complex hybrid systems consisting of both dynamic systems and discrete events: The use of variable step solver suffers from the disadvantage of greatly slowing the simulation for complex hybrid systems; meanwhile, the use of fixed-step solvers, improves the simulation speed, giving incorrect results because of the delays it takes into account for the discrete events (asynchronous with the simulation step) to the next simulation cycle, causing accumulating errors and phase shifts.
- Real-time simulation of hybrid systems: Only fixed-step solvers can be used for automatic code generation; however, a standard fixed-step solver of Simulink yields erroneous results, then applied to hybrid systems; and this may accumulate and cause drift and big phase shift. On the other hand, RT-Events applies a compensation algorithm to discrete events in real-time, resulting in a great precision.
- Real-time simulation of firing pulse units of power electronics: In rapid prototyping of power electronic systems, it is difficult to convert the controller outputs to switching signals that are sent to time-stamped digital outputs, by using comparators and timer blocks. The use of standard Simulink blocks causes high jitter because the lack of any timing information; when simulated at fixed-step in the order of 10 to 100 s, the firing pulses cannot be generated precisely unless timing information about the switching and state transitions is added to the switching state; and this is enabled by RT-Events.
