Adaptative high-gain extended Kalman filter and applications

tel-00559107, version 1 - 24 Jan 2011
Scicos call from
scilab console
Scilab call from the Konsole terminal
4.3 real-time Implementation
Real-time clock
Real-time task
Superblock
Figure 4.21: Graphical Implementation of a real-time task.
For portability and flexibility reasons, we used a Linux Live CD 14 comprising the RTAI-
Lab suite: RTAI-Knoppix 15 [3, 94]. When we operate in realtime, that is to say when an
observer is running, the RT tasks don’t require any hard drive access. Consequently there is
no difference between the linux live CD and a regular linux installation.
The development of a real-time executable is done from Scicos, launched from Scilab
as shown on Figure 4.21. A Scicos diagram, which is meant to be compiled as a real-time
application is composed of two blocks:
− an external clock (in red),
− a Scicos superblock that contains the whole real-time task (in black).
The only input to this block is the external clock signal. Communication between the system
and the real-time task is done using specific blocks (signal generation, Scopes, Analog/Digital
and Digital/Analog blocks [34]). They can be found in the RTAI-Lib palette 16 .
The graphical program obtained is compiled into a real-time executable with the help of
an automatic code generator. Figure 4.22 shows the three steps of the compilation:
14 A Live CD is an O.S. that deploys directly from the CD. No specific installation is needed on the host
machine. The programs and real-time tasks can be provided via an external storage source as a USB key.
In short, as far as the various softwares are concerned, the only hardware devices required are the CD with
RTAI-Knoppix and a USB key.
15 The version we used was built on a Linux kernel, 2.6.17 (SMP enabled kernel is available) and embedded
with
− RTAI version 3.4
− Scilab-4.0/Scicos CACSD platform.
16 In Scicos language, a palette is a collection of predefined blocks.
78