Upping the Raspberry Pi’s Field of View

My last analemma attempt was only the 22nd successful attempt in the history of mankind and after a break of nearly four years, I’m finally ready to try again. This time I hope to automate the process using a Raspberry Pi computer.


The factory camera for the Raspberry Pi comes with a tiny lens that has a Field of View of about 67 degrees diagonal(53 degrees Horizontal and 41 degrees Vertical). As any analemma enthusiast will tell you, this FOV just barely meets the minimum FOV needed (I will post details on this soon) to achieve a full figure-of-eight image with enough room on the sides for a nice foreground image. So the only way I can get my Pi to capture a full analemma is by changing the factory lens.

Luckily this is done quite easily. I followed the excellent instructions posted here to remove my factory lens and fitted an M12 (12mm) mounting bracket from a old broken webcam in place of the factory lens. Unfortunately the mounting screws did not line up with the holes provided on the Pi’s camera PCB and so I just glued it into place. This is what the result looks like…

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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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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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Haptic Controlled Robot Hand

This project brings together the DIY Haptic Control Glove and the Robotic Hand that I made earlier. The cost of this entire project was less than 25 US$. For details on how they were built and how they work, just follow the link for each.

This video demostrates the complete project.

1. Calibration of the glove
2. Control of the fingers
3. Touching finger tips of little and index fingers to demonstrate
thumb movement
4. Performing a simple task
5. Detail of servo movements

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DIY Haptic Control Glove

To test the working of a robot hand like the one I built earlier, I needed a haptic control glove that would encode the flexing of my fingers into electrical signals. These signals would be interpreted by a microcontroller (like the ATMEGA328 on the Arduino platform) and cause the servo motors on the robot hand to mimic my finger movements inside the glove. Electronic puppetry.

Robot Hand needs a puppeteer

Robot Hand needs a puppeteer

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Building a Better Robotic Hand

The word robot comes from the Polish word ‘robota’ meaning forced labour. In Russia, robota means just work, employment or operation. Funny, I’ve spent nearly two years in Russia and have probably spoken this word many many times, never really realising that it is also the root word for robot!

Anyway, this post is a photo-essay/tutorial on how I built my new robotic hand.

Everything is in place

Robotic Hand Version 2.

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DIY Servo Motor: Cheap and with Plenty Muscle!

DC Motors can be made to turn either clockwise or counter-clockwise by changing the polarity of the voltage applied to their terminals. The torque that is generated at the output shaft can be scaled up or scaled down by using a gear train.

What is torque? In simple words, torque is a quantity that decribes the ‘strength’ of a motor. A motor torque of 50 kgcm means that lifting a 50kg weight at 1 cm could be achieved with that motor. By the law of moments, lifting 50 kg at a distance of 1 cm is equivalent to ……

Lifting 500 kg     at 0.1 cm
OR    Lifting 5 kg        at 10 cm
OR    Lifting 0.5 kg        at 100 cm

In most motors, like the one shown below, the gear train scales up the torque of the motor by using a reduction gearing that outputs a much higher torque (albeit at the cost of a much reduced output RPM).

Geared DC Motor

Geared DC Motor: This one generates 120kg-cm torque at 3.5 RPM

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