Final Project: Automatic Nerf Dart Shooter (aka LaikaBlaster)



My final project was inspired by my dog who can't stop jumping on the sofa or the bed.  My goal is to use a sensor to detect when she's in a spot she's not suppose to be in, and frighten her off.

I had planned to use a PIR sensor initially, but it turned out to be too senstitive.  Essentially, it will go off anytime there's motion in the room, not just a certain area.  So I decided to use an ultrasonic sensor instead, and look for an "obstacle" in a certain area by detecting a change in the range.  I used the EZ-1 ultrasonic sensor which has a range of 6.45m.
                                                                   Sensor                                           UltrasoundSensor

I created a schematic to capture the sensor signal and to drive a DC motor.  My plan was to reuse the motor in an existing USB turret, and integrate the sensor with it by driving the motor when the proper signal is detected.  The DC motor is driven through a MOSFET circuit.



I was able to control the motor with the sensor with this setup.  

However, after a few tries in using the motor (possibly because I ran it continuously connected to a power supply), the gears had trouble converting the motor's rotation into linear actuation.


I will have to go back to replace the gears.