I wrote last night about interfacing the PC joystick (Or two giant pots and a couple of switches.) I knew that I wanted to build an airsoft turret. One of my students gave me an old airsoft gun which I took apart to figure out how they work. Basically there is a small DC motor that compresses a spring. The spring releases from a point of maximum compression and hits a piston which compresses air inside a cylinder. The compressed air fires a small 6mm plastic BB. Rather then using the gun he gave me I decided I had better start from scratch since I wanted my turret to be as light weight as possible.
I bought a crossman automatic airpellet gun and cut it down. I built a two axis platform using a 805BB servo for the base and and GWS S06 for the tilt. I really should support the gun from both sides since there is a lot of torque on the shaft of the S06.
The two servos are driven from a picaxe which is also interfaced to the joystick as I discussed previously. The gun is fired by triggering a logic level mosfet which is controlled by the trigger button on the joystick. I am running the servos and the gun motor off of one 2A 6V supply. The motor draws about an amp. The two servos together draw about 700 mA. The logic is run off a separate 5V supply.
My daughter and I hung up about a half dozen balloons to use as targets. We had a great time blasting away. but we are lousy shots. (Wearing safety googles of course!) I experimented with a targeting laser, but would need to make a mount that would let me dial it in to roughly match how the turret is pointing. I think my daugther enjoyed picking up the little plastic balls more then anything else. (I suspect I will be finding little plastic balls around the house for years to come.)
To Do:
- Potentially redo mount with a U bracket design instead of the current L for additional stability.
- The cheesy plastic box wobbles like mad. I should build a wooden box to mount this on.
- Mount Camera (I just confirmed that my wireless mini camera is still mounted on the robotic arm.)
- Mount Laser.
- Design serial interface to allow PC control. (This will be a variant of one of the many arduino based Serial Servo boards I have made).
- Write software in Roborealm for target acquistion.
Below is a video of the turret in action.
In the final picture below, you can see the turret, electronics and joystick.
