# Invisible fence

Discussion in 'Homework Help' started by Azkart, Jan 21, 2009.

1. ### Azkart Thread Starter New Member

Jan 21, 2009
4
0
Hi.
I'm currently working on a robot that needs to stay inside a small area, the area is limited by a invisible fence which frequency is of 10 Khz, the problem that I'm facing is that adding a coil on every side of the robot in order to detect the fence will take a lot of space (if you count the space needed for each one of the circuits for each coil). The frequency is generated from an underground cable.

2. ### hgmjr Retired Moderator

Jan 28, 2005
9,030
218
If circular, what is the circumference of the robot?

hgmjr

3. ### Azkart Thread Starter New Member

Jan 21, 2009
4
0
The robot is a square robot and the field is square as well.

4. ### hgmjr Retired Moderator

Jan 28, 2005
9,030
218
Maybe it would be practical to wind a coil around the perimeter of the robot. It would then be one big coil. You might then need to use a 10KHz bandpass filter to make the pickup coil and detection circuitry sensitive to 10KHz only.

hgmjr

5. ### Azkart Thread Starter New Member

Jan 21, 2009
4
0
Thanks, I will give it a try, although I don't know how to deal with changing the result to a digital signal so the microcontroller can read it.

6. ### mik3 Senior Member

Feb 4, 2008
4,846
69
If your uC has a built in ADC then it will be fairly easy.

7. ### calvintennant Member

Jan 21, 2009
27
0
Good call Hgmir! That is thinking outside of the box. Azkart, what is the function of said robot, other than containing itself.

8. ### italo New Member

Nov 20, 2005
205
2
DO YOU KNOW THAT THE TIME IS ONLY .0001MS If it gets too fast that might not stop it. try infrared invisible until you cross it easy to inplement just one LED and some mirrors make it any shapeyou like.

9. ### Azkart Thread Starter New Member

Jan 21, 2009
4
0
Thanks for the help, the robot needs to wander around the designated area without leaving it.