Building an XY Plotter

An XY plotter is a machine that can control a plotting instrument (such as a pen or a cutting tool like a blade or a laser) over two axes in a accurate, precise manner. Computer Numerical Control (CNC) machines are very accurate XY plotters than can be used for anything from decorating cakes to cutting steel plates into very precise shapes and sizes.

I wanted to make a drawing robot that would be able to draw the contours of a human face, so I decided to experiment with some very basic stepper motors and a cheap toy plotter that I bought on the Internet. Unfortunately, the plotter itself is so poorly manufactured that it is useless as a drawing tool, but the whole project gave me much insight into the steps needed to design a build a proper computer controlled plotting machine.

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KEEP OUT: Aussies on Patrol

I’m not a very political person. I don’t care much for international relations, economic policies and other such crap. But here is something that popped up on my screen while I was surfing the web, and I was so appalled that I had to write this post.

It is a poster created by the Australian Customs and Border Protection Service, directed at refugees fleeing persecution, headed towards Australia. Let me reiterate….this is not propaganda from the right wing lobby, this is the voice of the Government of Australia!!!


What disgusts me is that this policy is in complete and utter disregard to Article 14 of the Universal Declaration of Human Rights, which states that every human has a right to seek, and be granted, asylum from persecution. Whats even more outrageous is that Australia has managed to come up with an immigration policy like this even after it has ratified the UDHR.

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Look Ma, No Wires!

Reliable high speed wireless connectivity between two or more Arduino boards is something that everyone wanting to get rid of a tabletop tangle of wires will eventually need to implement. As part of my ongoing ERP project, I have decided to modify the ERP chassis to carry a GPS and an array of ultrasonic rangefinders. By establishing a wireless datalink, I hope to be able to build an outdoor mapping robot that would be able to map its surroundings and transmit a 3D image back to a base station.

3d Mapping

3d Mapping by a robot. Image from


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Printer’s Hat : Much More Than Just a Hat

A Printer’s Hat is very easy to make. Even little children can learn how to fold it very quickly.

It is made from eco-friendly newspaper, fully biodegradable and has many many uses. It makes a super paper plate for chips and munchies at a picnic or at a campsite. Its great for holding soil for seedlings, lined with a plastic bag it can hold water, and painted or plain, it makes an attractive hat!

Here is my youtube video on how to make a Printer’s Hat!


Interfacing a USB GPS with an Arduino

Now that ERP1 is up and running, it needs to be able to fix its position and report this back over the wireless data link. I plan to develop a simple Kalman filter to estimate ERP’s position, but to do this, I need two things…..

(a) An Action Parameter. This will be in the form of a motion vector. Direction will come from a digital compass and Magnitude from a  wheel mounted optical encoder.

(b) Data Update. This will the estimated position of ERP1 obtained from an external fixing system such as the popular Global Positioning System (GPS).

GPS Constellation. Source : Wikipedia

GPS Constellation. Source : Wikipedia

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Experimental Robotic Platform Part 3: Wireless Commands and Remote Control

In this post I outline the progress made on ERP1 (Construction and basic electronics onboard ERP1 can be reviewed here) over the past few weeks…

ERP 1. Wireless Mobile Robot

ERP 1. Wireless Mobile Robot

The robotic arm is now fully operational. It has 6 Degrees of Freedom and can be controlled remotely from any laptop running the interface software.The robotic hand is capable of simple tasks such as lifting and carrying small objects. I have attached a wireless AV camera to the robotic hand. A human operator can now “see” what the robot is doing and issue commands accordingly over the wireless data link.

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Grab Every Hilltop

Let me see if I understand how Israel does what it does…..

1. Claim a historical/religious belonging to the land.

2. Buy up whole swaths of land from poor farmers. Settle there, reproduce, buy more land. Repeat.

3. If the locals rise up in opposition, massacre them. Assassinate the internationally recognised mediator trying to resolve the issue. Blow up a hotel while the going is good.

King David Hotel. Blown up by the IRgun in 1946 under the orders of Menachem Begin

King David Hotel. Blown up by the Irgun in 1946 under the orders of Menachem Begin. See 4 below.

4. It doesn’t matter that you ran a terrorist organization, you can still win a Nobel Peace Prize. Yes, thats right, a Nobel Peace Prize!!

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Experimental Robotic Platform : Part 2 – Electronics and Radio Communication

Once the Chassis for my Experimental Robotic Platform was complete, I got to work on the electronics and control sections of the robot. Here are some details about the electronics of my ERP:-

1. Power Supply.

Power Supply

Power Supply.

Power for the 4 high torque DC motors comes from a single 1.3Ah 12 V battery. The second battery (the taller one) is a 4.5 Ah 6V battery that will power the micro-controller unit (an Arduino Mega) and the six servos that control the robotic arm. Once basic testing operations are completed, I will add two more servos for a pan-tilt sensor mechanism (wireless camera/ sonar ranger/ IR sensor etc) that will also draw power from this 6V battery.

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Experimental Robotic Platform Part 1 – Building the Chassis

After successfully completing this superb online course from Stanford University on Machine Learning, I am now quite confident with designing and programming neural networks. Also, playing around with the incredibly powerful openCV library has got me experimenting with computer vision. If I were to try and put these two powerful tools together, and the most obvious outcome would be intelligent, vision capable robots.

But before I get into any of the complex programming needed to create these robots, I first need to build myself a proper ERP, an Experimental Robotic Platform. So this weekend, I spent most of my time working on an ERP chassis……….

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Robot Navigation with a Particle Filter

As robots become smarter, faster and more capable, they are being developed to perform increasingly complex tasks. In order to perform these tasks properly, robots are becoming more and more dependent on accurate navigation through the environment in which they operate. Somewhere in the future, if intelligent robots were to rise up and demand fundamental rights, I think one of the first things they would ask for is the answer to the question, “Where am I?”.

Where am I?

Where am I?

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