Skills Used: CAD (Siemens NX), Engineering Design, Rapid Prototyping, Arduino, Engineering Analysis

Personal Project (First Prototype) to aim and shoot a Nerf Gun (01/24-12/24)

Timeline: 1/2024 - 12/2024

Goal: Learn Design by doing

At the time of this project, I had little experience in design or prototyping, but really wanted to understand the process of designing a product. In order to do this, I decided to make this robot to shoot a DartZone Pro Mk-III. I thought that making something fun would be a good introduction to design. I started working on this project with a friend of mine but ended up owning the design myself.

The goal of this robot is to aim and shoot a DartZone MKIII Pro Nerf Gun at a human with a budget of under $1000.

Design Process

Concept Sketch

  • Set forward customer requirements and turned them into engineering specifications through engineering analysis

  • Brainstormed ideas to make initial concept

  • Made model of robot in CAD using engineering analysis to guide dimensions.

  • Manufactured robot using 3D-printing and aluminum machining

  • Tested various subsystems of robot

    • Motor Control

    • Trigger Assembly

    • Turntable

    • Gun mount

Some Customer Requirements

Prototype

Turntable Prototype

Pololu Motor Driver and Dual Motor Driver

Most of the first prototype turned out well. Here were some features:

  • 3D-modeled assembly using Siemens NX

    • Gun mount using slot to connect to nerf gun accessory rail

    • Trigger-Actuating Assembly using slider-crank linkage

    • Turntable with 3D-printed Bearing (low-load)

  • Electronics and Computer Vision

    • Two different DC motor driver boards connected to Arduino Uno and 12V Lead-Acid Battery

      • One for turntable (higher power)

      • One for trigger and lifting motor

    • Tested YOLO Person Recognition v8 model on computer with OpenCV

Nerf Gun in Gun Mount

Nerf Gun Mount with Trigger Mechanism CAD

Test Results/Next Steps

Test Results

    • Issue: Nerf gun jams easily

    • Fix: use different nerf gun (which requires redesign)

    • Result: Rotation worked well, even under load

    • Issue: contact between motor pinion and outer ring gear caused loud whining

    • Fix: lubricate gear race or make gears same material

    • Issue: Aluminum stock connecting turntable and Gun Mount had significant flex.

    • Fix: Add 3D-printed bracing on top

    • Result: Nerf Gun rail fit in slot very well

    • Issue: Rail is sometimes too hard to get into

    • Fix: make rail length smaller

    • Result: Printed several iterations of slider-crank linkage

    • Result: Tested motion and fit

    • Issue: Stroke length was too small

    • Fix: make stroke length longer

    • Result: Soldered header pins onto board and tested DC motor control with Arduino IDE

    • Issue: Motor Driver boards not running

    • Fix: Debug code

    • Result: Tested OpenCV person tracking with YOLO

    • Issue: person bounding box makes it hard to find center of body

    • Fix: use body position tracking or face tracking model instead

Nerf Gun Robot Side View CAD

The Next Steps for this project are to completely redesign the robot using knowledge gained from the test results to reduce design flaws.

Previous

BD-22
Next

Desk Organizer