Adaptative high-gain extended Kalman filter and applications

tel-00559107, version 1 - 24 Jan 2011
4.3 real-time Implementation
3. the RTAI version (i.e. 3.4) that is embedded in the RTAI-Knoppix has an error in
the application file that links the Scicos Analog/Digital block (Analog to digital) of the
RTAI-lib palette to the real-time executable end file. The consequence of this error is
that is that it is impossible to measure more than one signal. After a few discussions
with the RTAI community, a solution was provided to us by R. Bucher in the form of a
corrected version of the faulty file: rtai4 comedi datain.sci. The correct code is given in
Appendix C.1. The files to be replaced are located on the virtual file system UNIONFS
deployed by the Live CD, in the following repositories:
/UNIONFS/ usr / s r c / r t a i −3.4/ r t a i −lab / s c i l a b / macros /RTAI/
/UNIONFS/ usr / l o c a l / s c i l a b −4.0/ macros /RTAI/
It is also necessary to recompile the file in the second repository using the shell command
s c i l a b −comp r t a i 4 c o m e d i d a t a i n . s c i
To do this, one need only to copy/paste the code of Appendix C.1 in any text editor, save
this file with the name rtai4 comedi datain.sci and perform the following commands
(MY USB KEY has to be replaced with the correct path name):
sudo rm /UNIONFS/ usr / l o c a l / s c i l a b −4.0/ macros /RTAI/ r t a i 4 c o m e d i d a t a i n . s c i
sudo rm /UNIONFS/ usr / l o c a l / s c i l a b −4.0/ macros /RTAI/ r t a i 4 c o m e d i d a t a i n . bin
sudo rm /UNIONFS/ usr / s r c / r t a i −3.4/ r t a i −lab / s c i l a b / macros /RTAI/..
r t a i 4 c o m e d i d a t a i n . s c i
sudo cp MY USB KEY/ r t a i 4 c o m e d i d a t a i n . s c i /UNIONFS/ usr / l o c a l / s c i l a b −4.0/..
macros /RTAI/ r t a i 4 c o m e d i d a t a i n . s c i
sudo cp MY USB KEY/ r t a i 4 c o m e d i d a t a i n . s c i /UNIONFS/ usr / s r c / r t a i −3.4/ r t a i ..
−lab / s c i l a b / macros /RTAI/ r t a i 4 c o m e d i d a t a i n . s c i
sudo cd /UNIONFS/ usr / l o c a l / s c i l a b −4.0/ macros /RTAI/
s c i l a b −comp r t a i 4 c o m e d i d a t a i n . s c i }
The real-time platform is now fully functional.
The I/O signal is sampled sufficiently fast as compared to the motor time constant. We
implement the continuous version of the adaptive high-gain extended Kalman filter. The
general structure of the observer is the same as before. It is displayed in Figure 4.26 together
with the corresponding Scicos diagram:
− as before the observer consists of two user defined functions that work in quite the same
way as Matlab S-functions,
− the update of the observer equations is performed continuously and the computation
of the innovation is done in the discrete time framework,
− a delay block of length d guarantees that we have access at time t to the estimated
state computed at time t − d (with the default value being equal to the initial guess of
the observer)
− two Analog/Digital blocks get the measured voltage (control variable of the machine)
and current (output variable of the machine),
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