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# Robot sound localisation

Question asked by jman in #Robotics on Feb 20, 2009
jman · Feb 20, 2009
Rank E1 - BEGINNER
Hi

I have the following project:

I need to build a robot with 2 microphones attached to it on either side. The robot is placed on a 4x4 meter grid. 2 speakers are placed on the top and left side of the grid respectively. They each output a specific frequency.

I need the robot to establish its coordinates based on the sounds received from the 2 speakers and then move to a specific coordinate...

Any ideas?

Thanks Posted in: #Robotics
silverscorpion · Feb 21, 2009
Rank A3 - PRO
I dont get it. Are there only two speakers and they transmit only two frequencies, right?
Then how can you fix your co-ord based on the reception of those frequencies alone?
Do you plan to use the signal strength that you receive to find where you are?
jman · Feb 22, 2009
Rank E1 - BEGINNER
Yeah, one speaker transmits around 600hz and the other around 1200 hz. I was planning to possibly use triangulation of some sorts to find the position of the robot. However, Im not sure how to implement that... The robot is also initialised at the centre of the 4x4 m grid and so it initially knows where it is...

Here is a picture of the grid

speaker 1
<------------------ 4m ----------------->
^ -----------------------------------------
| |
s | |
p | |
e | |
a 4m | .(2,2)
k | |
e | |
r | |
2 | |
-------------------------------------------
jman · Feb 22, 2009
Rank E1 - BEGINNER
sorry the point (2,2) needs to be in the middle but the forum doesnt edit it properly
Kaustubh Katdare · Feb 22, 2009
Rank A1 - PRO
jman
sorry the point (2,2) needs to be in the middle but the forum doesnt edit it properly
Don't worry. The forum automatically removes the spaces.
silverscorpion · Feb 22, 2009
Rank A3 - PRO
As i already said, you are planning to use the signal strength from each speakers to determine where you are. As i understand this, there will be two speakers giving out two different frequencies, located orthogonal to each other. The bot will initially be in the center.

Tell me, if the bot's movement restricted to only right angled movements? ie, if the robot has to turn, is it allowed to turn only in a direction perpendicular to the current direction? or can it move in any arbitrary direction? if it's the latter case, then localizing becomes difficult.
if it's the first case, divide the arena into equal area cells, and you need to know how the signal strength of each speaker reduces with respect to distance. If you get more of speaker 1 and less of speaker 2, you are closer to no.1. And based on the previous location, you can decide if it's one cell closer toward speaker 1 or speaker 2. that's the way to go. But it doesnt seem to be easy.

Anyways, all the best.

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