Specifications

2 CHAPTER 1. INTRODUCTION
The third and last option is described in this report. Using I/O boards with onboard processors no
extra interface and hardware is needed. The boards are plugged in the PCI Bus of any PC. Writing the
drivers as S-functions
2
and using a Real-Time target, Real-Time Simulink executables can be directly
interfaced from Simulink and model parameters can be changed on-the-fly in the same model. The
hardware is cheap and requires no additional PC as with the xPC concept. However the Real-Time
performance depends both on the Operating System and the PC-speed/specifications.
Why this DACS? The biggest advantage of the third option is the ease of use. Simply construct a
Simulink model and build an executable. No additional models are needed, e.g. compare this with
control lab for the dSPACE system. In general, the Simulink model will already be available from
simulations before the experiment is conducted.
Of course there are disadvantages too. There are never Real-Time drivers for data acquisition
boards. However within the (open source) Comedi project [1] there are drivers available for an increas-
ing number of boards. Having to write the drivers makes this option far more time-consuming than
the other two options.
Above all the urge to try something new and the challenge a project like this brings, is the motive
to undertake it. The objectives for this report are:
• Make rapid control prototyping possible using Real-Time execution of Simulink models.
• Plan of attack.
– The Linux OS has to be patched with RTAI for Real-Time execution.
– Matlab Simulink has to be made available in this platform.
– A Real-Time-Workshop (RTW) target is needed and available [4].
– S-function device drivers.
First it is shown how to implement all the system’s hard- and software. How Linux, RTAI, Matlab
and the data acquisition boards need to be installed and used. Further the results of some simple
experiment are presented to evaluate the performance. Finally the appendices give a step-by-step
installation procedure for the software.
2
These are c-code files which can be used in Matlab Simulink.