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21.6.11

Resample a Matrix in Matlab

This function does the same as the previous one (resample) but for a matrix. Again, maybe not the most elegant, but works


function newmatrix=resampmatrix(matrix,newlen)

%----------------

%this function uses linear interpolation to change the number of rows in a

%matrix.

%Copyright, 2011, Andrés González


%----------------

[rows cols]=size(matrix);

newmatrix=[];

for i=1:cols

len=rows;

x=1:len;x=x';y=matrix(:,i);

xx=1:(len-1)/(newlen-1):len;

xx=xx';

yy=interp1(x,y,xx,'linear');

newmatrix=[newmatrix yy];

end

Resample in Matlab

This is a simple function to resample a vector in matlab. I now there might be more elegant ways to do it, but this one works and it's simple

function newvector=resample(vector,newlen)

%%%%%%%%%%%%%%%%%%%%

%This function uses linear interpolation to change the number of samples

% Copyright 2011 Andrés Gonzalez

%%%%%%%%%%%%%%%%%%%%

len=length(vector);

x=1:len;x=x';y=vector;

xx=1:(len-1)/(newlen-1):len;

xx=xx';

yy=interp1(x,y,xx,'linear');

newvector=yy;

end

10.6.11

RTAI installation on Linux (Kind of ultimate tutorial)

Well, I think this might be of interest to some people working with control systems in real time. Linux could be a good choice depending how skilled you are with it (the truth is, everything in Linux requires you to be a. very skilled and b. very patient).
Link
A brief description:
RTAI: Real-time environment for Linux ( https://www.rtai.org/ )
COMEDI: It's an interface for sensing and control devices (http://www.comedi.org/doc/)
Scilab/Scicos: A computational package, kind of a Matlab-Simulink, but open source ( http://www.scilab.org/)
HART Toolbox: A group of modules to work with RTAI using Scicos ( http://hart.sourceforge.net/index.html )

I spent several weeks trying to make it work all together so no, it's not straight forward always (but, who knows, you could be lucky). But this tutorial can make it easier (I hope)

Most of it is taken from http://hart.sourceforge.net/rtai_installation_10_04.html and adapted to solve some of the most common problems.Without further introduction, here is the tutorial:


Installation RTAI

Packages:

UBUNTU 10.04

Install the following packages to proceed:

general:

sudo apt-get install cvs subversion build-essential

rtai:

sudo apt-get install libtool automake libncurses5-dev

comedi-lib:

sudo apt-get install bison flex

comedi-calibrate:

sudo apt-get install libboost-dev libboost-program-options-dev libgsl0-dev

scilab 4.1.2:

sudo apt-get install gfortran sablotron tcl8.5-dev tk8.5-dev xaw3dg-dev libpvm3 pvm-dev libgtkhtml2-dev libvte-dev ocaml-native-compilers

qrtailab:

sudo apt-get install libqt4-dev libqwt5-qt4-dev

Installation of all components

RTAI kernel from EMC

echo deb http://www.linuxcnc.org/lucid lucid base emc2.4 > /tmp/linuxcnc.list

echo deb-src http://www.linuxcnc.org/lucid lucid base emc2.4 >> /tmp/linuxcnc.list

sudo mv /tmp/linuxcnc.list /etc/apt/sources.list.d/

gpg --keyserver pgpkeys.mit.edu --recv-key 8F374FEF

gpg -a --export 8F374FEF | sudo apt-key add -

sudo apt-get update

sudo apt-get install linux-headers-2.6.32-122-rtai linux-image-2.6.32-122-rtai

If there is a problem downloading the patched Kernel, you can try this (taken from http://www.rtaixml.net/realtime-suite/part-2---machine-setup)

sudo wget http://sourceforge.net/projects/rtaixml/files/realtimesuite/1.0/realtimesuite-1.0.tar.gz/download

Decompress the downloaded file, navigate into the subfolder “kernel” inside realtimesuit-1.0, and run the .deb installers

Reboot in the new installed RTAI-kernel.

RTAI (https://www.rtai.org) #1

(cvs-Version)

cd /usr/src

sudo cvs -d:pserver:anonymous@cvs.gna.org:/cvs/rtai co magma

sudo ln -s magma rtai

(tar.gz-Version)

cd /usr/src

sudo wget --no-check-certificate https://www.rtai.org/RTAI/rtai-3.8.1.tar.bz2

sudo tar xjvf rtai-3.8.1.tar.bz2

sudo ln -s rtai-3.8.1 rtai

Installation of RTAI

cd /usr/src/rtai

sudo make menuconfig

Ensure directories are correct:

Installation: /usr/realtime

Linux source tree: /usr/src/linux-headers-2.6.32-122-rtai

Under Machine, choose number of CPUs (check running cat /proc/cpuinfo and verifying how many processors are listed)

sudo make

sudo make install

sudo sed -i 's/\(PATH=\"\)/\1\/usr\/realtime\/bin:/' /etc/environment

now run export PATH=/usr/realtime/bin:$PATH for each open shell or do logout and login Now we need to load the rtai modules.

/sbin/insmod /usr/realtime/modules/rtai_smi.ko

/sbin/insmod /usr/realtime/modules/rtai_hal.ko

/sbin/insmod /usr/realtime/modules/rtai_lxrt.ko

/sbin/insmod /usr/realtime/modules/rtai_fifos.ko

/sbin/insmod /usr/realtime/modules/rtai_sem.ko

/sbin/insmod /usr/realtime/modules/rtai_mbx.ko

/sbin/insmod /usr/realtime/modules/rtai_msg.ko

/sbin/insmod /usr/realtime/modules/rtai_netrpc.ko

/sbin/insmod /usr/realtime/modules/rtai_shm.ko

Copy the lines to /usr/local/bin/start_rtai

Do a sudo chmod a+x /usr/local/bin/start_rtai

If there is trouble inserting the rtai_hal.ko module then:

Go to boot/grub/menu.lst or boot/grub/grub.cfg and add “lapic” at the end of this line:

kernel /boot/vmlinuz-2.6.22-realtime root=UUID=45d21232-cf0d-cc3d-87ce-8453214d7a6f ro quiet splash vga=794 lapic

COMEDI (www.comedi.org)

cd /usr/local/src

sudo cvs -d :pserver:anonymous@cvs.comedi.org:/cvs/comedi login

sudo cvs -d :pserver:anonymous@cvs.comedi.org:/cvs/comedi co comedi

sudo cvs -d :pserver:anonymous@cvs.comedi.org:/cvs/comedi co comedilib

sudo cvs -d :pserver:anonymous@cvs.comedi.org:/cvs/comedi co comedi_calibrate

sudo cvs -d :pserver:anonymous@cvs.comedi.org:/cvs/comedi co comedi-nonfree-firmware

If the comedi server is down, you can also find the packages in:

http://www.mev.co.uk/comedi/

Download them and decompress to /usr/local/src

COMEDILIB

cd /usr/local/src/comedilib

sudo sh autogen.sh

sudo ./configure

sudo make

sudo make install

sudo mkdir /usr/local/include/linux

COMEDI

cd /usr/local/src/comedi

sudo sh autogen.sh

sudo ./configure --with-linuxdir=/usr/src/linux-headers-2.6.32-122-rtai --with-rtaidir=/usr/realtime

sudo make

sudo make install

sudo make dev

sudo ldconfig

sudo depmod -a

COMEDI-CALIBRATE

cd /usr/local/src/comedi_calibrate

sudo autoreconf -i -B m4

sudo ./configure

sudo make

sudo make install

RTAI #2

sudo cp /usr/local/src/comedi/include/linux/comedi.h /usr/local/include/

sudo cp /usr/local/src/comedi/include/linux/comedilib.h /usr/local/include/

sudo ln -s /usr/local/include/comedi.h /usr/local/include/linux/comedi.h

sudo ln -s /usr/local/include/comedilib.h /usr/local/include/linux/comedilib.h

cd /usr/src/rtai

sudo make menuconfig

Under “Add-Ons”, select “Real Time COMEDI support in user space”

Check COMEDI installation directory, it should be /usr/local/

sudo make

sudo make install

sudo cp /usr/local/src/comedilib/include/comedilib.h /usr/local/include/

Now we need to load the comedi-modules. All rtai modules have to be loaded before! This is a example for the ni 6024e.

modprobe comedi

modprobe kcomedilib

modprobe comedi_fc

modprobe ni_mio_cs

insmod /usr/realtime/modules/rtai_comedi.ko

comedi_config -v /dev/comedi0 ni_mio_cs 0x0100

comedi_calibrate --calibrate

chmod a+rw /dev/comedi0

Copy the lines to /usr/local/bin/load_daq

Do a sudo chmod a+x /usr/local/bin/load_daq

If there is a error message "comedi.o not loaded", then you have to create and edit /etc/modprobe.d/comedi and add one of the following lines:

options comedi comedi_num_legacy_minors=4

(you can change the number 4 if you want), or:

options comedi comedi_autoconfig=0

The first option, comedi_num_legacy_minors=4 reserves 4 comedi devices for use by non-autoconfigured devices. The second option comedi_autoconfig=0 disables auto-configuration completely.

If there is this error:

comedi_calibrate: error while loading shared libraries: libcomedi.so.0: cannot open shared object file: No such file or directory

Then do:

cd /lib/

ln -s /usr/local/lib/libcomedi*

SCILAB 4.1.2

cd /opt

sudo wget http://www.scilab.org/download/4.1.2/scilab-4.1.2.bin.linux-i686.tar.gz

sudo tar xvzf scilab-4.1.2.bin.linux-i686.tar.gz

cd /opt/scilab-4.1.2

sudo wget http://hart.sourceforge.net/scilablibs.tar.gz

sudo tar xvzf scilablibs.tar.gz

sudo make

sudo ln -s /opt/scilab-4.1.2/bin/scilab /usr/local/bin/scilab

QRTAILab (www.qrtailab.sf.net)

(svn -version)

cd /usr/local/src

sudo svn co https://qrtailab.svn.sourceforge.net/svnroot/qrtailab/trunk qrtailab

(tar.gz - version)

cd /usr/local/src

sudo wget http://downloads.sourceforge.net/qrtailab/QRtaiLab-0.1.12.tar.gz

sudo tar xvzf QRtaiLab-0.1.12.tar.gz

If you use a tar.gz-version please replace qrtailab with qrtailab-x.x.x (x.x.x is the number of your installed version )

cd /usr/local/src/qrtailab

Edit qrtailab.config and replace '/usr/include/qwt/' with '/usr/include/qwt-qt4/' and '-lqwt' with '-lqwt-qt4'

sudo qmake-qt4

sudo make

sudo make install

HART Toolbox (www.hart.sf.net)

Chose a directory (/home/username/software, ...)

(svn -version)

svn co https://hart.svn.sourceforge.net/svnroot/hart/trunk hart

(tar.gz -version)

wget http://dfn.dl.sourceforge.net/sourceforge/hart/hart_0.4.1-src.tar.gz

tar xvzf hart_0.4.1-src.tar.gz

Go in your hart-directory.

Edit Makefile and set 'SCILAB = ...' to the binary file of scilab 4.1.2

Warning: sudo make will not install RTAI module! Either be a normal user and install HART or change to root (using sudo su) and then do make.

make

cd /..../scilab-xxx/contrib

sudo ln -s {link to hart-toolbox} .