This is an update on my latest project, a fully functional airsoft sentry gun!
Click here and take a look at the detailed pictures,plans and videos!
Let’s start with the basic material. All parts were cut out of 2 or 3 mm PMMA Acrylic glass. I used Inkscape to generate the gears and since the lasercutter I could use ran on Adobe Illustrator, I had to design all the parts with AI. Here you can see the lasercutter cutting some of my parts:
If you are interested in the plans of all the parts, consider making a small donation here and I’ll be happy to send you all of my plans via e-mail!
Here are all the parts right before assembly – it was my first try at lasercutting so some parts got a little bit dirty due to not cutting with the protective foil still attached. Furthermore while cutting Acrylic one should avoid sharp edges and rather cut round corners!
Above you can see the BB feeder‘s parts. The most difficult task here was designing a working “BB feeder gear”.
The parts were glued together with hot glue. Next time I will include holes for assembly screws. The motor you can see here is a cheap metal geared DC motor.
The gears were cut with a slot so they fit right onto the motor’s axis.
These two are the baseplate and the rotation platform gear.
You will notice a square piece of acrylic in the middle of the disk. I installed a piece of acrylic tubing in order to be able to guide cables through the middle while rotating around more than 360°.
These are the parts which make up the tilt mechanism. Here from a different angle:
The stabilizers fit right onto the big plate using pre cut slots. The next pictures show baseplate and tilt mechanism together:
Now I need your help. I am going to use an Arduino Mega and some motorshields for controlling the turret. I have no incremental sensors so far – please send me an e-mail or leave a comment with a link to what sensors I should use. I dont want to use optical encoders, I’d prefer some variable resistors or some kind of similar sensors!
The project is not yet finished: Lasers, infrared Leds and a camera will be added. Motion tracking and remote control will be the final task. Watch the video below for some explanation and demonstration.
http://www.doityourselfgadgets.com
Attach some rotary potentiometers to the axles. Tie them to the analog inputs on the mega and you have some very simple absolute feedback. The drawback is that you wouldn't be able to do infinite turns, so you'd have to limit your range on each axis.
Make your project opensource and you'll have an army of makers helping you out.
you could use stepper motors for precise "step" movement.
or if you want to keep the original motors, use some optical encoders. if you want to do it a more DIY way, grab the brushless motors from a few scrap HDD and use those as encoders.
this is a good optical encoder w/ arduino examples: https://www.sparkfun.com/products/9117
here is go over using a hdd motor as an encoder with an arduino: http://dduino.blogspot.com/2012/01/hdd-rotary-encoder-with-interrupts.html
What you are trying to build is a servo motor. Just a high powered one. You can go out and buy a digital one and rip out the Position sensors and just add it to this guy here. Its the same thing. Or you can ReInvent the wheel. Here is some good info. http://en.wikipedia.org/wiki/Servomotor
Already trying to do it opensource 🙂 – posting everything i got!
Thank you for your comment! I'll take a look into that! Sounds very promising!
Thank you so much!
Really nice build man! Makes me want a laser cutter (although I really like my CNC router too)!
Actually you can. Take out the pot stops and you are set. They will spin all the way around, though there will be a dead zone. You could use two 180deg to each other to get over this.
How about simply putting microswitches near the gears in such a way that when the gears rotate, the teach hit the microswitch. So you will be able to calculate how many increments it has done, then simply calculate the angle from that.
Wow nice project picture shown in this post.I like all the pictures post by you.
Two suggestions make your own optical encoding by painting a "gray coded" pattern on the two gears and use led/detectors for each band you wish to use. This way you can easily get 8 to 10 bits of location accuracy with that many sensor pairs. A mega has plenty of pins to handle that.
One option would be to add a magnet inserted into a hole in the gears and use some hall effect sensors to detect it . This way you could do one on the horizontal axis, and two on the vertical to know where the ends are. Then do some measuring for time required to move between detections. Some sensors can distinguish polarity of the field so if you monitor the pulses you could figure out where you are.
Or you could embed magnets can a gray coding scheme so with an array of hall effect sensors you could determine where you are.
print black dots on the outer edge of the gears and use a LED and a LDR to sense movement
have you ever thought about mounting a camera under the barrel and connecting the leads to a joystick. essentially making it a remote sentry?
Sant Ritz's charming address offers a world of opportunities for your little ones in the future.the interlace
I did think, the camera connect to a smartphone and the main turret to a ps3 joystick and put a red or green laser and a on off switch connected to the arduino so you can remotely control everything
are you willing to donate that to me please
Why not consider merely adding microswitches on the equipment so that Create store cards whenever your equipment swivel, your teach attack your microswitch. Consequently it will be possible for you to compute the number of increments it offers accomplished, then merely compute your point of view coming from that will.
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Do you sell any of these??