Help with 75 MHz Transmitter & Receiver

Hi all! I am currently designing a robot for my Engineering class and the controller is giving me some problems.

The robot has to be controlled through a Steel Sheet Metal tunnel. My robot loses signal about a quarter of the way through the tunnel without fail. It regains signal when I point the transmitter inside the tunnel when I am standing next to it. However, I can not do this during the actual project. Do you guys have any ideas? I tried adding an antenna and soldering the Receiver to it, yet that was no better. My professor said the antenna should’ve helped slightly and she would talk with the electronics department about it. Do you guys have any tips or advice? I’m stumped.

If you simply need to travel in a straight line from one end of the tunnel to the other, and if you can find a software development environment (EasyC, RobotC, or one of the other ones) that lets you tell the robot to continue operating autonomously, even though the robot isn’t detecting a transmitter signal, then you could try letting the robot travel unguided through the central region of the tunnel.

I remember having trouble with robot software that wouldn’t execute at all if the robot wasn’t receiving a 75 MHz transmitter signal (I’m guessing that is your root problem); but I don’t remember the easiest way to use one/any of the software development products to work around that problem.

Do some research into your programming options, and check back here to see if someone else suggests (hopefully free) method.

Blake
PS: If you need to truly control the robot while it is in the tunnel, I don’t know any way to get 75 MHz radio waves through sheet metal; but I you might have some luck using ultrasonic sensors or light sensors while the robot is in the tunnel.