Heli Shooter

[physics-matt]

Ever since I got a small RC helicopter I've wanted to build a Lego system to shoot at it.

Well... here it is:

http://www.youtube.com/watch?v=NwXvXeMxCDo

https://sites.google.com/site/mattsrobo ... li-shooter

Let me know what you think!

Matt

[gloomyandy]

I think you are a very bad man!

Seriously do you have any footage from the bore sight cam?

Are you using standard firmware in the NXT-CAM? I guess the white wall makes it reasonably easy to pick out the copter?

Did the elastic bands really bring the copter down, or was that just a hollywood effect?

All very cool...

Andy

PS what happens if you walk out in front of it? Can we see a video of that!

[physics-matt]

I do have this video:

http://www.youtube.com/watch?v=KCPCW_DVXho

It shows the bore sight footage in the lower right corner and the rest is the display screen that I created for showing the tracking on the PC. Red blobs indicate a target detected by the cam but not the US rangefinder, green indicates it has also been detected by the rangefinder.

The video also shows what happens when I walk in front of it. I was too far away for it to shoot (thankfully).

I'm using the original firmware for the NXTCam, which is quite surprising as I didn't expect it to work without some modification. You're exactly right that the light wall helps a lot, but it's not perfect. I'm going to spend some time seeing whether I can improve the performance.

I also need to work on a way to actually bring the helicopter down (safely) - what you see in the video is indeed a "special effect" caused by me taking my thumb off the throttle. Ideas I have so far are either something that will get tangled up in the blades, or a focussed light source to saturate the IR sensor. However, I'm not sure how possible either are without risking damage to the helicopter.

Matt

[aswin0]

This gave me a big smile on my face!

Very very cool

[gloomyandy]

[quote="physics-matt"
I also need to work on a way to actually bring the helicopter down (safely) - what you see in the video is indeed a "special effect" caused by me taking my thumb off the throttle. Ideas I have so far are either something that will get tangled up in the blades, or a focussed light source to saturate the IR sensor. However, I'm not sure how possible either are without risking damage to the helicopter.

Matt[/quote]

So are we talking "laser canon" here! How cool would that be! Best watch out the SDI boys may be paying you a visit...

Andy

[loopymech]

this put a big smile on my face too! I love auto-turrets.

can't wait to see the next iteration.

-Loopy

[nxtboyiii]

...I wonder if it works to shoot people too...
That is so cool!

[physics-matt]

The first turret I ever made had a webcam plugged into a PC with some face detection software and the "Competition cannon" (32074 & 32133c01) attached. That was very exciting... a turret that could track faces and shoot at the same time. Needless to say the missus always checks now before coming into the room

Unfortunately the NXTCam as it currently stands is unlikely to do anything that sophisticated, but maybe one day there will be a version with enough memory. In the meantime, I've got some ideas to get the tracking and discrimination a bit better, although I think it's likely to remain a "dark blob on light background" job for a while yet.

Matt

[loopymech]

perhaps you could 'rig' the env with bright colored dots on the heli to help the nxtcam?

[physics-matt]

I was thinking of rigging the heli with something bright, but I guess it just feels wrong to do so... I mean, a helicopter infiltrating into your airspace is unlikely to have convenient bright dots on it. I've also thought about getting another RC heli that is bright red, but again, just doesn't feel "right".

Of course, it's not as if I'm not rigging it by having a light wall behind!

I'm going to try and make the system more robust to clutter, as well as having big objects (i.e. me) go in front of it. The former could be done by making a note of where stationary objects are in the scene (though the heli is likely to be able to hide by flying in front of them) and the latter by rejecting objects that are very large (which can be roughly done in real terms since I have the rangefinder measurements)

Matt