Determining sound direction

I've been playing a bit more with datalogging (check out the fantastic tips from Brian in the forums) and I've always wanted a robot that could come to me when I called it. The sound sensor is great for 'detecting' sound but no good for deciding where the sound came from. One way to figure out where the sound is coming from is to use 2 sound sensors.

So I built myself a little NXT head that had 2 sound sensors and a bit of foam in between.

"Sure it's pretty" I hear you say, but whats that foam in between the ears for?

Well I figure that if I had 2 ears, with some sort of dampening material in between, the ears would hear the same sound source, but at different volume levels.

ie. If I clapped my hands very loudly on the left hand side, then the left 'ear' would hear a certain volume and the right 'ear' would also register a sound, but at a much quieter level.

So I set up my head and start writing sound readings from both the left and right ears to a text file as fast as I can. I'm not too concerned with the sampling rate, as I'm more interested in the difference in sound levels for the same 'clap'

I take the results and put them through Excel where I subtract the value of the right ear from the value of the left ear to give me a difference.

Now if the clap happens directly in front (or behind) my NXT head, then the sound levels will be the same and the difference will be 0. But if I clap off to the left hand side, then the left reading will be higher than the right reading and my difference will be a positive number. If I clap on the right hand side then I'll get a negative number.

This graph shows the difference between the left and right ears with 3 test claps, once on the left, once in the center and once on the right.

From this I can see anything under -40 is a definite clap on the left and anything over +40 is a clap on the right.

So now I can write a program that takes the two sound sensor readings and subtracts one from the other. If the result is more negative than -40, I turn clockwise a small amount. If it is greater than 40, I mover counter-clockwise for a small amount.

I think with more sound dampening, I could probably get it to respond a little more accurately.

--
Damien Kee

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The ROBOTMAK3RS continued their celebration of the 25th Anniversary of MINDSTORMS through these Fall and Winter remix projects. Each ROBOTMAK3R was tasked with selecting one LEGO set of their choice and combining it with a MINDSTORMS set. Below are the five amazing models they came up with. Braill3 by Jerry Nicholls Braill3 is an EV3-based LEGO Braille bricks reader. This robot uses its fingertip, made from three touch switches, to read messages written using the LEGO Braille bricks and will speak out what it detected. If it sees a simple maths problem it will attempt to solve it and give the answer as well. To learn more about the process of creating this machine, read Jerry's blog . Braill3 can be viewed here . Set Review: The Braille Bricks set is well thought out. The ratios of the letters is suitable for general use and the addition of some punctuation and arithmetic operators is excellent. There is a card showing what bricks there are and their quantities, but no form of sort

Celebrating MINDSTORMS with a Remix - Part 2

The ROBOTMAK3RS continued their celebration of the 25th Anniversary of MINDSTORMS through these summer and fall remix projects. Each ROBOTMAK3R was tasked with selecting one LEGO set of their choice and combining it with a MINDSTORMS set. Below are the five amazing models they came up with. Remote controlled material handle r by Jozua van Ravenhorst (aka Mr Jo) This remix combines the LEGO Technic Material Handler (42144) with MINDSTORMS EV3 (31313) It uses the power of pneumatic cylinders to move objects around. By using a bluetooth remote control, very precise movements can be made with this model. Touch sensors in the base chassis prevent the turret twisting the cables that go through the turntable to much. The program has several protections to prevent over pressurizing the system for each of the 3 individual pumps and valves that control the 2 booms and claws. The real version of this machine is mostly used in waste material sites to bring the material to machines that sort and

Celebrating 25 Years of MINDSTORMS

In celebration of the 25th Anniversary of MINDSTORMS, we take a trip through history. Please also visit ROBOTMAK3RS Community every week as we highlight different projects all through 2023 in celebration of the anniversary. Some of the early history is based on the content shared by Coder Shah in our MINDSTORMS EV3 Community Group . Some of the text and links may have been edited from his original posts for consistency and clarity. 1984 - Kjeld Kirk Kristiansen watched a TV program called "Talking Turtle," where MIT professor Seymour Papert demonstrated how children could control robot "turtles" using LOGO, a programming language he developed. 1988 - The collaboration between MIT and LEGO resulted in LEGO TC Logo in 1988, which allowed students to control LEGO models using computer commands. The video shows Papert demonstrating TC Logo. 1990 - LEGO TC Logo was hampered since the robots you built had to be tethered to a personal computer. LEGO and MIT

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