MSnipe

Inspiration

MSnipe was a spur of the moment idea that originated in the fact that one team member owned an electronic Nerf gun.

What it does

MSnipe uses an auto-targeting system based upon an ultrasonic distance sensor and a stepper motor. The stepper motor turns a turntable from 0 to 180 degrees, and when the ultrasonic sensor senses a distance less than its maximum range, the turret momentarily pauses and fires a dart at the target.

How we built it

There a 3 main aspects to the turret system; 1) the triggering mechanism 2) the turntable mechanism and 3) the microcontroller. The triggering mechanism involves a servo motor mounted to the side of the handle of the nerf gun, which when directed by the microcontroller, essentially pulls the switch mechanism responsible for the trigger reading. The turntable is made from two 3D printed gears, one attached to the base of the nerf gun which acts as a turntable, and a smaller, keyed gear that attaches to the stepper motor. The microcontroller is an Arduino Mega 2560 which directly controls the servo motor with PWM, indirectly controls the stepper motor through a driver chip, and reads the analog voltage values from the ultrasonic sensor. The base of the turret is made from miscellaneous wood pieces.

Challenges we ran into

There were many challenges involved in this project, including problems with mounting, controlling motors, and reading sensors. The triggering mechanism used a servo to pull a switch, but this switch had to be extracted from the internals of the nerf gun as the servo was no powerful enough to actually pull the trigger. The switch was removed from the casing with new wiring soldered onto it, as the existing wires were not long enough. This switch had to then be mounted in a way that the servo could touch it with its rotating arm. The servo triggering mechanism had to be lined up with the switch perfectly for this to work. The turntable and how to move the turret back and forth also proved difficult, and after some design iterations with different bolts and different stepper mounts, a 3D printed gear system was devised and decided upon. The ultrasonic distance sensor was troublesome as it has a wide view angle, and thus detected motion not right in front of it. This causes the turret to fire without any real target. The seemingly simple setup of the stepper motor took the better half of the day, and the unipolar stepper motor was never able to run.

Accomplishments that we're proud of

We are proud of the fact that we created a working product that had a subset of the features we had hoped for on this project. We worked through coding errors, wiring mistakes, mechanical challenges, and various other obstacles and created a decent project.

What we learned

We learned about Arduino, sensors, 3D printing, motors, and much more. We learned how to control stepper motors and also how to read analog sensors.

What's next for MSnipe

The MSnipe turret system needs a more powerful motor upgrade, LIDAR distance sensor, and extended magazine system. These are all future improvements for MSnipe. Using OpenCV on python on Raspberry Pi for real-time image tracking and recognition is a reach goal.