1
\$\begingroup\$

I'm building various r/c vehicles like warplanes, tanks, auto-turrets, etc. and I want to fit some of them with some kind of a weapon. I've decided an air soft gun is a good choice. So, mounting and shooting the gun is easy. The problem begins, when I want to create a software damage model for my vehicles. I need to find a way to detect when and where my model was hit.

I'm thinking about to layers of plastic or some other slightly elastic mterial, each covered with sth conductive. They are placed close together. When a bullet hits one, it bends, touches the other and the current flows. However it doesn't seem to be a very elegant solution. Especially when it comes to hit angles like 60+ degrees or centrifugal forces acting on my plane. I don't think it will also work on sloped surfaces like airfoils etc. I will also probably fail on thin surfaces, because the sensor would be quite thick itself - the upper layer, the conductive things, the gap, etc.

Is there a better way of doing this? I'm really out of ideas so any help means a lot. Also, please don't tell me how good/bad my idea is. I just need to find a solution to a problem.

Thanks, Kiel366

P.S.: I don't need an exact hit location. Locations like: wing, elevator, first half of the fuselage are totally fine.

\$\endgroup\$
  • \$\begingroup\$ Elan Sel'Sabagno: "You wanna buy some death sticks?" Obi-Wan Kenobi: "You don't want to sell me death sticks." Elan Sel'Sabagno: "Uh, I don't wanna sell you death sticks." Obi-Wan Kenobi: "You want to go home and rethink your life." Elan Sel'Sabagno: "I wanna go home and rethink my life." \$\endgroup\$ – Techydude May 16 '15 at 23:13
5
\$\begingroup\$

I think using modulated laser diodes and/or LEDs and photodetectors of some sort would be a much better idea. Basically, turn it in to a game of laser tag. It is much easier to detect an incident light beam than it would be to detect an impact, and you can transfer information about what sort of a weapon that it represents and who is firing it in the modulation. You can get remote control receivers quite cheaply from some places and these will give you a demodulated digital output. It would be simple to mount them in various places and monitor all of the outputs with a microcontroller to figure out where you got hit. On the other end, all you need is an IR LED or IR laser diode that you modulate at the same frequency the detector is looking for. If you gate the modulation with a serial signal (i.e. UART) then you can pass along information about what type of weapon it represents and who fired it and decode this at the receive end.

If you really want to detect impacts, a piezoelectric solution may be the way to go. The hard part will be making a solution that is insensitive to orientation and vibration while also being able to cover the entire external skin of the vehicle. There will likely be a significant tradeoff between false negatives and false positives and it could be very difficult to make it robust enough for your purposes.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ +1, that's exactly what I thought. Mounting "real" guns on an RC plane does not seem a good idea to me. \$\endgroup\$ – Vladimir Cravero May 17 '15 at 8:20
  • \$\begingroup\$ Ok, but what kind of photo detectors could cover the whole area of the plane, generate little drag and work in full sunlight? Btw: oh come on! Real weapon? Shooting 6mm 0,2g plastic balls that after 30m in flight lose all of their energy?? Asg is better than lasers because the bullets don't fly straight: are affected by gravity and centrifugal forces and don't move at the speed of light, which is way more realistic. Really isn't there a good way of detecting impact? \$\endgroup\$ – user2462898 May 17 '15 at 11:07
  • \$\begingroup\$ I have a pair of RC helicopters that shoot at each other with IR, the one that's hit goes tumbling down. Remember there's no need for the shooter to be the transmitter, you could have send IR pulses from the target, and search for them with the "cannon", might simplify the processing. \$\endgroup\$ – tomnexus May 17 '15 at 16:43
  • \$\begingroup\$ Well, the optical approach will be the most robust. If you want to detect a physical strike, it's going to be a very significantly more complicated problem. You have to find a solution that will reliably detect an impact while at the same time being insensitive to vibration, high speed air flow, orientation, etc. This is not going to be a very easy thing to do. Additionally, to make it robust enough to not get overwhelmed with false positives, you may need to crank the sensitivity down so low that you will start missing hits, especially glancing ones. \$\endgroup\$ – alex.forencich May 17 '15 at 23:51
  • \$\begingroup\$ And the idea with photodetectors is not to cover the entire surface, but to de-focus the laser diodes so that you don't need to cover the entire surface with detectors. \$\endgroup\$ – alex.forencich May 17 '15 at 23:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.