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Project 2

Catapult

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Design an automated catapult that senses target distance, adjusts its launch mechanism, and hits targets accurately at varying ranges.

Overview

The Catapult project requires teams to design and build an automated projectile launcher using the provided electronics and mechanical components. The system must be capable of detecting target distance and adjusting the launch mechanism to accurately hit the target.

Teams will integrate sensing, control systems, and mechanical design to create a fully automated catapult capable of aiming and firing projectiles at targets placed at varying distances. The intended high-end path is automated target finding and directional aiming using the provided sensor workflow, while the rubric below still distinguishes between full and partial automation.

The project encourages creativity in embedded programming, mechatronics, and system integration.

Objectives

Participants must design a system that:

  1. Identify and measure the distance to the target using the VL53L0X V2 Time-of-Flight sensor.
  2. Calculate the required launch and aiming parameters.
  3. Adjust the catapult mechanism automatically using motors.
  4. Launches a projectile to hit the target as accurately as possible.
  5. Display system information on the OLED display for monitoring or troubleshooting.

Materials Provided

Item Picture Description
Raspberry Pi Pico 2 Raspberry Pi Pico 2 microcontroller board. Main controller for the catapult. It reads the sensor, computes shot settings, drives the actuators, and updates the on-board display.
VL53L0X V2 Time-of-Flight (ToF) laser ranging sensor VL53L0X time-of-flight distance sensor breakout board. Measures target distance so the launcher can choose the correct shot profile or automate tower finding in higher-end builds.
MG996R 360 servo MG996R 360 degree servo motor. High-torque servo for heavier mechanism motion such as cocking, feeder drive, or another powered stage that needs more torque than the small servo can provide.
MG90S micro servo MG90S micro servo. Smaller actuator for light tasks such as a latch, gate, sensor mount, or release linkage.
NEMA 17 42 stepper motor NEMA 17 stepper motor. Provides repeatable positioning for an aiming axis, turret, or adjustable launch geometry where precise motion matters more than raw speed.
DRV8825 stepper motor driver with heat sink DRV8825 stepper motor driver carrier with heat sink. Interfaces the Pico to the stepper motor and provides current-limited, direction-and-step control for accurate positioning.
LM2596S DC buck converter LM2596S adjustable DC buck converter module. Steps the main supply down to cleaner lower-voltage rails for logic, sensors, and any peripherals that should not be fed directly from the higher-power input.
12V 6A power supply unit 12 volt 6 amp power supply unit. Primary bench supply for the launcher, especially during tests where motors, drivers, and other higher-current loads need a stable source.
0.96" OLED display module 0.96 inch OLED display module. Useful for distance readings, calibration state, selected firing mode, and other live debug information during setup and testing.
Perfboard 7 x 9 cm 7 by 9 centimetre perfboard. General-purpose prototyping board for soldered wiring, small interface circuits, and more durable assembly than a temporary breadboard.
USB-A to Micro-USB cable USB-A to Micro-USB cable. Used to power and program the Pico during development, testing, and firmware updates.

Common Materials

  • Mini Precision Screwdriver Set
  • 2-meter 22AWG Single Core Wire
  • M3x10mm Screws
  • Assorted Electronic Components Kit
  • 12 Value Assorted Capacitor Kit

Quickstart

  1. Start with VS Code Setup and Power & Wiring before you integrate the full launcher.
  2. Prove the Pico 2 can read the VL53L0X V2 and command one actuator cleanly.
  3. Get consistent launches with a 30 mm projectile before you automate reload or tower finding.
  4. Treat automatic target finding and directional aiming as part of the high-end solution, then layer extra automation on top.

Projectile Rules

  • Use 30 mm diameter 3D-printed balls as projectiles.
  • Each kit will include 3 projectiles for testing.
  • There is no limit on the number of extra projectiles your team may print, as long as they remain 30 mm in diameter.
  • A magazine or similar reload mechanism is strongly recommended.

Tower Layout Reference

A tower reference image will be added here before launch. Until then, use the distances and scoring rules below as the source of truth.

Inspiration Reference

The main inspiration for this project was the Instructables project Arduino Robot Catapult:

Teams may find it useful as a high-level reference for automation flow, launch sequencing, and general mechanism ideas.

Important constraints for this project:

  • Treat the Instructables build as inspiration only. The Hack-A-Bot kit is materially different from the parts used in that project.
  • Use of the external 3D files from that build is not allowed in this project.
  • If you borrow ideas from it, you should adapt them to the components, geometry, and constraints of the kit provided here.

These photos are copied from the Arduino Robot Catapult Instructables page and are included only as visual reference for mechanism layout, actuator placement, and launch sequencing.

Exploded layout of the Instructables robot catapult parts, electronics, and printed panels.
Exploded parts-and-electronics layout from the original reference build.
Assembled Arduino robot catapult with controller board and electronics visible beside the mechanism.
Full assembled view showing overall geometry, actuator positions, and control wiring.
Close angled view of the catapult arm and launch cup loaded with a yellow ball.
Loaded launch position showing the arm linkage, cup, and feed path.
Side profile of the assembled robot catapult showing the lever arm and servo-driven structure.
Side profile that makes the main arm motion and support structure easier to read.
Close-up of a catapult trigger or feed subassembly with servo horn mounted to a white plate.
Subassembly close-up for one of the servo-driven moving stages.

Common Failure Points

  • inconsistent projectile size or mass between test shots
  • trying to solve reload, scanning, and launch power at the same time
  • unstable power delivery when multiple motors or drivers move together
  • mounting the sensor in a way that cannot reliably see the towers

Programming approach

VS Code is the primary recommended workflow for this project. Start with VS Code Setup for toolchain bring-up and Power & Wiring before running launch hardware at full load.

  • Recommended path: VS Code
  • MicroPython or Arduino IDE can still be used if your team already knows them, but treat them as secondary options

Scoring Criteria

Maximum score: 100 points

The project rewards automation, accuracy, engineering quality, and software implementation. Systems with higher autonomy levels receive higher marks.

1. Level of Automation (50 Points)

System Type Description Points
Fully Autonomous System System measures distance, calculates launch parameters, aims, and fires automatically with no human input. 50
Semi-Autonomous (Manual Aim + Automatic Launch) Users align the system with the target direction, but the system measures distance and automatically calculates launch parameters and fires. 30
Distance-Assisted Launch System measures distance and displays recommended settings, but the user manually adjusts and triggers the launch. 15
Fully Manual System User performs aiming and launching manually without automated assistance. 0

2. Accuracy Scoring - Block Target System (40 Points)

The target will consist of 6 columns of 3 stacked blocks, arranged by distance from the catapult at marked positions around a circle with the catapult in the center.

Target Layout

  • 2 Close Columns (0.8m)
  • 2 Middle Columns (1.3m)
  • 2 Far Columns (1.8m)

Teams aiming for the fully autonomous category are expected to locate and aim at these towers automatically. Lower automation categories are still scored using the rubric above.

Calculation method:

  • Only the top two blocks in each column count toward scoring. The bottom block does not count, even if it falls.
Number of boxes fallen* distance multiplier
Distance Multiplier
Close 2
Middle 4
Far 6
  • Total score after 5 shots is the score for accuracy

3. Engineering & System Design (5 Points)

Judges will assess:

  • Stability of the mechanical structure
  • Quality of assembly and wiring
  • Effective use of provided components

Score: 0-5 points

4. Innovation & Creativity (5 Points)

Points may be awarded for:

  • Creative catapult designs
  • Unique engineering solutions

Score: 0-5 points

Supporting Documentation

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