Let's Make Robots!

Laser Tag and Recoil


It's me and my laser tag project again. This time you'll read about me trying to find a solution to simulate the recoil of real weapons to make laser tag more realistic and cool to play.

First part of the page will be, as usual, the brainstorming part. That means that i really do not know what i'm gonna use for the recoil mecahnism (and if i will be using one, if it gets too complicated or costly i'll just abandon this idea) so i ask you for suggestions.

 What does it have to do to properly simulate recoil?:

- it has to be a fast mechanism considering i might get up to 15 virtual bullets per second (it might also work once every to bullets, bringing the count down to 7 "loops" per second at most)

- it is preferrable if the mechanism works with electricity and not gas or air

- it has to be a bit powerful, not too much but at least it has to give you the "blowback" feeling

 What i have considered so far: 

not much actually. I have read that solenoids might do the job, but i don't know whether they are fast enough and where to buy them. I also checked out linear actuators but they seem to be costly and slow. Dual shock-like motors (the ones you find in xbox/ps/wii controllers) are the easiest and cheapest solution, but i'd keep this as a last resort, in case i can't come up with anything else, because they don't give you a "kick", they just make the gun vibrate (not very realistic). 


I am concentrating especially on solenoids. They look interesting, but i really do not know where i can get fast and powerful ones. My idea is to attach a weight to the solenoid arm and switch it on and off everytime the user presses the trigger.

Any suggestion/idea? 


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Oh, now i go it, and i have to say it's not bad, because it doesn't take much space too. I don't think i am gonna find that disk anywhere though, maybe i could make it out of polymorph? or cut a sheet of plexiglass to form that shape.

I'll try to see if i can find the various parts for this setup. But still i got a doubt: you guys said that solenoids draw a lot of current, but having a strong and fast motor like one i would have if i used this setup isn't gonna draw as much? 

I suggest you start by thinking through some requirements:

  • How much mass you need to move will depend on the weight of the gun 
  • The spring needs to be sized for the weight defined above, also the amount of linear travel you need
  • How many RPM do you want the cam to turn? (how many "beats" per minute the user will feel)
  • The motor and gearing get selected for the right RPM and enough torque to set the spring

I would think a fairly small motor would do, but it depends on how heavy your laser tag gun is.

I bet can cut away from an existing gear or wheel to make the cam.

I don't have much idea about the mass actually , since i don't know how much kick each weight might give. My mind suggest me some 2 or 3 kilos, i think that would do.

As for the RPM, it would be nice to have a beat per virtual bullet, which is, at most, 15 beats per second.

I think i'll need to read myself some physics formulas as i have no idea on how to calculate the "power" of the spring i will need. 

The part Ezekiel has drawn is called a cam.  Pretty darn useful things whenever you want to translate a rotating motion to a actuator that varies.

You can probably scrounge some cams from something, or make your own pretty easily by cutting away from a normal wheel or gear.

I bought a couple from electronic goldmine to make a electronic door lock. I believe they will be fast enough, and definetly strong enough for your needs. The only problem I had was they were EXTREMELY noisy (electronically spaeking) --Sent from my mobile device

I am also building a laser tag system. I found this blog today while searching for other laser tag recoil implementations. For the recoil am experimenting with the cheap solenoid from electronic goldmine. I am building the gun out of PVC, so I rigged up the solenoid on a PVC pipe extender and connected it to three 9V batteries. I tried it twice, once with a 1-1/2 inch pipe and again with a 3/4 inch pipe. It worked much better with the smaller pipe. 




Want to team up? We could share knowledge about our projects! I'll definetly give a look to your videos to learn more.

EDIT: just watched the videos...MAN the second one is amazing! Can you get it up to a faster rate of fire? But still...could you tell me how you made it? It looks really cool. 

It was dead simple to make. I used a PVC extender coupling (http://tinyurl.com/krxfgd) with the o-rings removed. I taped a solenoid (http://tinyurl.com/kj3mp2) on the side. I drilled a hole through the center pvc pipe and used piece of a hanger as a pin to connect the solenoid to the pipe. The circuit was three 9V batteries in series and a switch, a big capacitor in parallel with the batteries, and a diode in parallel with the solenoid.


-The pipe didn't slide very well, so it would get stuck if I didn't have enough power. I tried lubercating the pipe, but it didn't help much. Something with ball bearings would work much better. You don't need a PVC extender coupling, it should the same with just two sizes of pipe.

-It may work better with a better solenoid driver circuit (switch debouncing, PWM signal, etc.).

I wonder what the rpm of the solenoid is under ideal conditions?

I am happy to share ideas, I've got some pretty ambitious ones. I am using the Arduino board (also from Italy) and plan to couple it with a PDA, Phone or netbook.

Thanks for the in-depth information! I am planning on using ATmegas programmed in arduino C. The laser tag i am planning to make is the mil-sim kind, but it could be turned into arcade in a few secs (you know...just tweak the code a little and you're done), even if i don't think i'll be doing that much (i am an airsoft player, so i like realism). 

So far i wanted to integrate things like these in the project:


-"near miss" warning (that is: if the data transmitted by one's IR led isn't received properly then the ATmega tells you somehow)

-magazines (i was planning on having, say, 5 magazines per player each with a different resistor, which has to be read by the ADC port on the atmega. The magazine doesn't store the bullet count, the ATmega does (=less contacts needed, simpler to build))

-grenades and maybe flashbangs (grenades shouldn't be hard, as for flashbangs, i thought about placing a few high output white LEDs on the player's helmet/cap so they turn on when the "flashbang signal" is received

-fully working cocking handle 

-other minor tweaks.... 


What about you? Are you going the mil-sim way too? Got some cool ideas to exchange? 

I guess the PDA/netbook coupling is for setting up a match quickly right? 


Oh, thanks for the information. Unfortunately, electronic goldmine doesn't ship to Italy, damn! But now that i've read your comment i guess i'll definetly have to try out solenoids.