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Ultrasonic GPS

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Furby

New Member
The aim of this project is to move a micro mouse to a x/y coordinate using an Ultrasonic 2D GPS for location detector.

An Ultrasonic transmitter will be placed at each corners of a 1m square.
These ultrasonic transmitter will be fired in a specific squence by the microC. The Ultrasonic receiver mounted on the micro mouse will received these transmissions and relay them, via an on board FM transmitter to the microC. This microC will then determine the micro mouse position and transmit further movement commands to the micro mouse and send current x/y position to PC so the position of the micro mouse can be displayed on the GUI.

I would like to check who can teach/help me on the designs of the :-
1) Ultransonic GPS transmitter design
2) Ultransonic GPS receiver design
3) FM data transmitter design
4) FM data receiver design
 

john1

Active Member
Hi Furby,

That sounds like an interesting project,
what ever do you want to do it for ?

And what does GPS stand for?
It cannot be 'Global Positioning System' surely?

I was not sure what a micro-mouse is so i looked it up,
for those who don't know,
its a miniature robot controlled by a micro-controller
that would(typically) find its way through a maze, or
presumably from A to B or some such task.

I suppose there are clubs or groups that are interested
in this sort of thing.

I don't see how the mouse could sense its position on the
1 metre square by sounds from the corners.

How do you propose to plot the position of the mouse ?

You say,
......an ultrasonic receiver on the mouse will receive these
ultrasonic transmissions and relay them via an FM transmitter
to the microC. This microC will then determine the micro
mouse position and transmit further movement commands ......

The bit i don't see is that bit which goes like this:
....will then determine the mouse position .....

How would it do that ?

John :)
 

tansis

New Member
I understand what you are trying to do.
But is it allowed under competition rules?

Surely a better use of ultrasonic range-finding would be to measure the distance in front of the robot to the next wall/turn. The range data could then control the maximum speed and braking....
 

Jimbo

New Member
john1 said:
The bit i don't see is that bit which goes like this:
....will then determine the mouse position .....
How would it do that ?
I suppose the signal strength received at the mouse from all four transmitters (you only need three actually) can be used to determine the distance to each of the transmitters (they'd have to send a coded signal so the mouse can differentiate between them, or even worse, use seperate frequency bands). Then you need to "draw" three imaginary circles around the transmitters with the radius equalling this distance information. The circles should then all cross in one point and one point only: the location of the mouse.

However I doubt that "home/kitchen/garden" electronics would ever work accurately enough to get reliable distance info from the antennas (we're probably talking resolutions of centimeters or even less), but I have a habit of being proven wrong :).

Another possiblity is of course that the project was described all wrong :D.
 

tansis

New Member
The robot has an ultrasonic sender, its signal is recieved by two sensors at the corners of the maze (whose dimensions and position are known).

This is an exercise in simple ultrasonic range-finding, instead of using reflected sound waves, the the proposed system uses the time taken from the robot to each of the sensors. The output of the sensors is then linked backed by radio to the robot.
 

townsvillian

New Member
Wouldn't it be easier to have a pulsating signal on the robot which pulses a signal at a regular interval? The receievers at the corner of the square detects the time and/or position of the pulse relays it back to the controller who can determine exactly where the robot is?

Then power can be conserved by the robot, and it can be used in any number of places, just by locating receievers in appropriate locations.
 

DirtyLude

Well-Known Member
Actually that first link kinda sucks, because it tries to deal with just volume localization. Picking out which microphone has the loudest sound. Here's some pretty techincal info:

http://www-2.cs.cmu.edu/~drulhe/perso/compvision/Source Localization.pdf

I'm planning on making something similar for a robot, but it's purpose would be just to detect a certain volume of noise and run away from it. I'll be using a 3 microphone array and compare elapsed time between detected sound signals.
 
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