Alex Sleat

Inverted Pendulum

As part of my Robotics university course we used an Inverted Pendulum rig to learn some control applications/algorithms. For extra marks we had the challenge to swing the pendulum from hanging down to an upright balancing position. Below is my first attempt which still needs a little tweaking to the values to reduce swings [...]

Error: “end_request: I/O error, dev sr0, sector xxxxx” – Linux

Error:

end_request: I/O error, dev sr0, sector 537392

If you’re getting a similar error filling your screen once you’ve installed Ubuntu, don’t panic. It’s pretty common which is basically because Ubuntu (or any other Linux distro) can’t control your CD/DVD drive properly, it’s probably trying to open/close it but doesn’t know if it has [...]

Failed to build Planner-0.14.4 in Arch Linux

When trying to install Gnome Planner ( http://live.gnome.org/Planner ) in Arch Linux, I came across this error:

Error:

/usr/bin/pygobject-codegen-2.0: line 11: /usr/bin/python2: No such file or directory make[2]: *** [planner.c] Error 127 make[2]: Leaving directory `/home/alex/Desktop/planner-0.14.4/python‘ make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/alex/Desktop/planner-0.14.4′ make: *** [all] Error 2

To fix this, I [...]

Wireless showing but fails to up/dhcpcd – Arch Linux

After my installation of Arch Linux I had some trouble using my wifi card which was working while I was running the live CD. What was strange was that the card would show up in iwconfig and ifconfig -a but not ifconfig It turns out I needed to install the wireless drivers and here’s [...]

Installing packages from CD in Arch Linux

Okay, so you have Arch Linux installed and let’s say you’re wifi isn’t working and you need the package “iwlwifi-3945-ucode-15.32.2.9-2-any.pkg.tar.gz” to fix this but you don’t have a wired connect. What do you do? Blast in your Arch cd, mount it, mount the packages sqfs file and install using pacman.

Mount cdrom:

mkdir [...]

How To Fix “Fatal server error: no screens found” | Ubuntu

If you’re running off a live USB disk or changing your graphics card the error below might appear when Xorg is looking for the wrong drivers or device. You might also get this error while using the Nvidia drivers, I found however this was caused by some of the extra options added into the [...]

Realtek RTL8191S in Ubuntu 10.10

Errors:

$ sudo ifconfig wlan1 up SIOCSIFFLAGS: Resource temporarily unavailable

$ dmesg usb rtl819xU:FirmwareDownload92S(): failed with TCR-Status: a rtl819xU:ERR!!! _rtl8192_up(): initialization is failed!

Solution 1:

To get this wifi dongle working I simply had to download the above firmware and place it in /lib/firmware/RTL8192SU/ and then reboot my computer. You should check that location [...]

HowTo: Mount USB Persistent casper-rw File in Linux

So, you’ve created an awesome Live USB Linux stick with a persistence file which let’s you boot anywhere and carry all your sweet sweet datas around on it too. If you want to see those files in Linux on your desktop or laptop outside the USB you’re going to have to mount the loop [...]

ImportError: No module named …

Numeric

Error:

Traceback (most recent call last): File "", line 1, in ImportError: No module named Numeric

Package:

sudo apt-get install python-numeric

ImageTk

Error:

ITraceback (most recent call last): File "", line 1, in ImportError: No module named ImageTk

Package:

sudo apt-get install [...]

Using pdfcrop to Remove White Margins | Ubuntu

One of the most annoying things about PDF files are their fixed font size, the only real way of getting a better view at the text is to zoom the whole page in. This isn’t really a fix for that annoyance but it’s a way of getting more info to screen ratio by removing [...]