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Our project involved designing and implementing a robust, precise racquetball launcher integrated into an Autonomous Surface Vessel (ASV) for the 2025 RoboBoat Competition. This international competition, organized by the Office of Naval Research, challenges teams to enhance the capabilities of autonomous boats. Our solution focused on combining advanced mechanical, electrical, and computer vision systems to reliably deliver racquetballs to specific targets.
Mechanical Launcher
Mechanical Launcher
The launcher integrates:
A compound gear-driven spring puncher, secured with a fang and sear plate system.
Servo-triggered gate for precise shot timing.
Indexing drum mechanism, rotating to sequentially position each racquetball.
Index Drum
Spur Gear
Compound Gear
Puncher
Wedge
Sear Plate
Index Ram
Triple Barrel Mag
Electronics Enclosure
Electronics Enclosure
Our electronics box includes:
An Arduino microcontroller to control launch sequences.
Magnetic encoders and hall-effect sensors for accurate positional feedback.
Waterproof enclosure ensuring marine-grade durability.
Isometric View of Electronics Box
Top View of Electronics Box
Computer Vision System
Computer Vision System
The vision system comprises:
OAK-D LR camera integrated with Jetson Nano NX.
YOLOv8 machine learning model and OpenCV for target detection.
Centroid-based calculations for precise launch command execution.
OAK-D LR camera
Using the camera and software to detect the target
Testing and Performance Results
Launcher Performance
Launcher Performance
Achieved excellent precision: x-spread = 0.0312 m, y-spread = 0.0338 m (standard deviation shown as purple-dotted line).
Reliable launch distances significantly exceeded the minimum 20-inch requirement
Graph showing scatterplot of 30 shots taken by our launcher
Graph shows the range of all the launchers versions
Computer Vision Accuracy
Computer Vision Accuracy
Successfully identified targets at approximately 7 meters.
Robust performance in various simulated marine conditions.
Testing computer vision
Water Resistance Tests
Water Resistance Tests
For this test we placed all of our hardware enclosures - servo, motor, hall-effect sensor, H-Drive Link - under continuous running water for 5 minutes. All of the hardware enclosures had cobalt chloride strips taped inside. Cobalt Chloride strips are blue, but when water comes in contact with the strips, they change colour to pink/white. This helped us know if any water leaked into the enclosure.
Testing procedure
Motor Enclosure
Testing Strips (Cobalt Chloride)
Servo Enclosure
Hall-Effect Sensor Enclosure
Iterations
Rev 1
Issue: Open-loop control led to inconsistent performance.
Gear Ratio: 1:1, limiting torque and reliability.
Rev 2
Improvement: Integrated a compound gear with a 1:1.5 ratio, accommodating higher spring force (3-tooth slip design).
Advantage: Introduced closed-loop control for significantly enhanced reliability and consistent shot performance.
Rev 2.5
Enhancement: Added a servo-driven pusher and a sear plate mechanism.
Benefits: Enables indefinite time between shots, improving operational flexibility (5-tooth slip design).
Rev 3
Major Update: Incorporated an indexer, an indexer rack, and a front-loading drum mechanism.
Result: Improved loading efficiency and further enhanced reliability and ease of use.
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