thought of such an experiment?

a friend and i plan to design and fabricate a sort of home radar/tracking system.the objective goes like this.there is a dark room and we are flying a remote controlled helicopter(a small one).it is desired that a radar/tracking system placed on the floor should track it,follow it and hit it with ping pong balls.now how to go about.we need to keeep this whole thing as simple as it could be.
we had an idea.make a hexagonal mirror drum.which rotates both in the vertical plane and the horizontal plane.360 degrees in the vertical and about 30-40 in the horizontal.rotation achieved by servo motors/stepper etc...we will position a laser beam and focus it on this rotating drum.this will scatter the laser rays in the whole room.any random ray striking the helicopter will illuminate it and a camera fitted on the rotating drum will lock the target,follow it.the rotation should stop now.and the feedback signal to a micro controller will do the analysis and fire the balls.gear trains needed..calculation of gear ratios needed.etc.what do u say?how credibile is dis?.
the objective is not to strictly do this in a room.it is aimed to b done in an open sky..think of this system placed on the ground..and above it(1 km)..in a balcony we fly a toy helicopter in any direction..this rotating head makes a three dimensional or spatial region saturated with laser beams(all reflected)...when this copter enters this area...the beam or beamS strike...a spot occcurs..and a camera on the ground captures and locks this location/co ordinate and and now follows the copter where ever it goes.

P.: i have dropped the idea of this rotating head and simply scrapped the idea of employing reflection...some people have sugested using galvos instead of stepper.share ur thoughts on this...

y not use a cam and a follower with a box containing a laser pen..this box lying in contact with the cam surface.the nature of the mechanism being oscillating cam follower...

this is all for detection purpose. there will be another system to identify the spot when the laser hits the helicopter.locks the co ordinates of the spot,and fires a ping pong at it...

Wow! An aggressive project, for certain.
I suspect that a hybrid approach may work better; first using sound (passive/active) and then switching to light or laser to stay within the forum. The reason I think sound would be better initially is that it is omnidirectional but easy to generalize the quadrant.
For example, for passive location, a matrix of 6 or so small microphones could be processed by the AD of a PIC. If the microphones are separated enough then all that is necessary is to sweep the microphones through an arc of say 170 degrees and analyze the voltage from each microphone. The angle of the platform and the highest voltage should give the general quadrant above the platform for a rough location.
Once the rough location is known, zoom in with an optical sensor. Let's assume that you have an array of 6 5mw red lasers and you sweep these through the rough location area. Using a lens and an array of 6 phototransistors, you should be able to determine which beam(s) are reflected brightest. Some experimentation needs to be done, but since you know the maximum distance the helicopter can fly inside the room, you can have the lens set to focus on that distance rather than set the focus at infinity.
The rest of the logic and mechanics would be to move the ping-pong-gun into position and fire it with a spring or compressed air. I would build and test each of the three sub-systems separately and then write PIC code to tie it all together. If you move the ping-pong-gun after the rough sound locating is complete, you will be closer to the desired area for firing and will not have such a long delay after the optical location is complete.
Crazy but sounds fun. Good luck.

Ray

Might be worth looking into a kinect hack for this kind of thing, might be able to get the IR dots to register the movement of the copter.