beige,

Your first two video guides are well done and kudos to you for doing them in a bilingual format (Mac and Windows).

Keep up the good work.

badri,

I assume that you are referring to two mobile robots.

How big is the area that they will be moving about (a room, an auditorium, or a large area outside)?

What level of accuracy do you need?

What will you do with the position data?

If you are only looking for a low level of accuracy, you could use a “dead reckoning system,” whereby both robots start at known positions, then determine their new positions by calculating the distance and direction traveled through encoder feedback. You would then need to transmit the new data through some kind of RF or IR link.

Assuming that the two robots are constrained to a relatively small area (room or auditorium) then a more complex method would be to use some kind of triangulating devices (two towers) that sensed and calculated the relative positions of the two robots. This could be done by either laser or ultrasound range finding (small room).

The second option using external range finding is more complex, more problematic and more expensive than either a dead reckoning or GPS based system.

Yowzer . . . I must be really old . . . not only do I remember those old Simpson meters, I also remember using VTVM's (Vacuum Tube Volt Meters) that needed to be plugged in and warmed up before use. They were however considered to be the gold standard of accuracy back when the likes of Nixon and Ford were the presidents of the United States.

http://www.flickr.com/photos/46450559@N05/4433313255/

This picture illustrates my multi-meter history going all the way back to high-school. That old Radio Shack Micronta analog meter was fully functional until about a year ago when my second of three boys got his hands on it. When purchased new in the mid-late 1970's it cost me the king's ransom of about $35 which must have been about two days pay pumping gas at my part-time job.

Ten years ago, I purchased a pair of the little black DVM's when I saw them on sale (marked down to $10 from $40) at my local Canadian Tire store. One lived on my bench and the other got dragged around in a cordura electrician's bag with screw drives, pliers and the like. They were nothing fancy, but gave yeomen's service until one bit the dust about a year ago and was replaced by that yellow one.

It's not name brand and at $60 I am sure I paid too much for it, but at the time it was the only one I could find with capacitance, transistor checking, frequency and temperature for less than $100. It works great although the tilt stand on it broke a couple of weeks after going into bench service.

That latest acquisition is that red UT33C made by UNI-T , that I picked up locally for the princely sum of $19 and to be honest is the nicest meter of the bunch. It's small, light weight and came with a type K thermocouple giving temperature in both °F and °C (which I frequently use). For the price it is great and the only things I would add if I could would be capacitance and frequency.
[media][/media]

Catcher you're not asking for much . . . just asking for everything. I really don't believe that there is a single free web-based ebook that will give you everything you want. However, there are real books that you would need to purchase or borrow from a public library that will give you all of the above.

Try to purchase or find a copy of, “Teach Yourself Electricity and Electronics” by Stan Gibilisco. Published by McGraw Hill (Tab Electronics) ISBN 978-0-07-145933-4. Most libraries in my area have at least one copy and if I had to start again from the beginning, it is the one book I would purchase from the get go.

This book is really a textbook that has everything you are asking for and then some, but at almost 700 pages, I cannot imagine trying to read it as an ebook . . . but I have been recently been re-reading my copy and am amazed at how much I had forgotten.

The next book I would buy is, “Getting Started in Electronics” by Forrest M. Mims and available at < http://www.forrestmims.com/>. For that matter any book by Mims is a good introduction to electronics and a great source for project ideas . . . unfortunately many seem to be out of print, but are available used from Amazon at reasonable prices.

Both of these books are well worth their price . . . remember, sometimes you get what you pay for!

However, there are a number of e-sources that will also help you:

The Complete Beginners Guide to the Arduino <http://www.earthshinedesign.co.uk/ASKManual/Site/ASKManual.html>

All About Circuits
<http://www.allaboutcircuits.com/>

Mike Cook's Tutorials
<http://www.thebox.myzen.co.uk/Tutorial/Introduction.html>

Play-Hookey . . . yes that is the name
<http://www.play-hookey.com/>

And of course no list would be complete without a little more Arduino content
<http://www.freeduino.org/>