The case of the 500 mile e-mail

Stumbled upon this story on HN, it’s worth a read.

The original story appeared on the SAGE mailing list in 2002, and serves as a kind of a reminder of the perils of configuring sendmail back then (The incidence had occurred probably in around anytime between 1992-97).

Double check on the on the units if you’re not running a linux box!

Integrating Eclipse’s menu with Unity’s Globalmenu (Ubuntu 13.04)

The following bug report in Unity makes it seem that Eclipse has been blacklisted from Unity’s global appmenu:

I wanted this done to reclaim some real-estate on my screen. The blacklist has been hard-coded in the binary and we need to replace the contents in order to work around it.

The workaround:

> cd /usr/lib/x86_64-linux-gnu/gtk-2.0/2.10.0/menuproxies
> sudo sed -i 's/Eclipse/Xclipse/'

This works great, however I’ll suggest taking  a backup of before changing it. Good luck!

Visualizing my facebook network

Visualizing my facebook network

Click on the photo for an interactive visualization.

I’ll be working to provide further interactions (growth of the network along a time axis, more details on the nodes, the clustering algorithm, prediction of the closest friends taking messaging/interaction frequency into consideration). The between-ness and centrality isn’t perfect yet.

[How to] Build your own Robot Arm – A beginners guide (1)


Update on September 1, 2013: The sources, documents, designs has been pushed to OpenRobo

Original post:

Here I will show you how to go about building your own personal Robot Arm. This is meant for those who are inexperienced and amateurs in Mechanical Engineering but have a decent Electronics/Software background. However this also means if you are a budding enthusiast in this field you will definitely able to understand the directions and guidelines with just a little bit of patience.

So you’ve decided to build your own Robot Arm and need to know where to start off from and what problems to think about. This guide is based on my experience of building my ow version of the Lynxmotion Lynx 6 Robot Arm while at college.

Here’s the things you need to know and care about:

  • Mechanical Aspects: Kinematics and Dynamics of the Arm
  • Electronics/Software Aspects: To build a brain to control the Robot

Of course there are diverse approaches you can follow, I’ll show you what seemed best to me for a first timer.

We were majors in Electronics and CS, and had to learn a decent amount of the statics and dynamics involved to proceed with our design. We encountered several shortcomings as we proceeded and hope to provide a decent background on what things can go wrong.

Before you start off you should know and understand well the terms: Degrees of Freedom, Forward Kinematics, Inverse Kinematics, Statics and Dynamics. Every bit of the math involves Linear Algebra and Matrices with various transformations.

The best place to start off is to attend the CS223A Introduction to Robotics course by Prof. Oussama Khatib.

Find the video lectures on youtube.

I’ll be showing the architecture of our arm and the control methodology used in the next post.