Unmanned Surface Vehicle (USV) Design and Build
Ziad Tamim / February 15, 2023
This project involved the design, development, and testing of a low-cost Unmanned Surface Vehicle (USV) tailored for search and rescue (SAR) operations in shallow waters. The aim was to create a portable, affordable, and reliable solution that first responders could rapidly deploy in emergencies such as drowning incidents, floods, or river rescues.
Unlike traditional manned rescue vehicles, this USV minimized risks to human rescuers by offering autonomous navigation, real-time underwater video feed, and long operational endurance, all while staying within a modest budget.
Objectives
- Design & Build: Construct a USV with autonomous waypoint navigation for systematic search missions.
- Affordability: Keep the total build cost below £500, making it accessible to small rescue teams and communities.
- Performance: Ensure the USV could operate autonomously for at least 1 hour, cover 200 meters, and maintain a top speed above 7 km/h.
- Underwater Detection: Integrate a live camera system to detect victims or hazards in real-time.
- Portability: Build a system that could be carried, deployed, and controlled by a single operator.
Background & Motivation
Search and rescue missions are often hindered by difficult terrain, high operational costs, and risk to human rescuers.
- Commercial USVs cost between £8,000 – £50,000, making them unattainable for smaller organizations.
- Many lack affordable yet effective underwater detection systems, relying instead on costly sonar solutions.
This project sought to bridge the gap by delivering a functional prototype that is:
- Lightweight and cost-effective,
- Capable of autonomous missions,
- Equipped with underwater vision technology,
- Adaptable for future enhancements like sonar or thermal imaging.
Design and Development
1. Mechanical Design
Hull Structure:
- Adopted a twin-hull catamaran design for stability and efficiency.
- Built from laser-cut foam boards, coated with two layers of epoxy for rigidity and waterproofing.
- Each hull housed compartments for LiPo batteries and ESCs, distributing weight evenly.
Dimensions:
- Length: 90 cm
- Width: 75 cm (contractible to 55 cm)
- Height: 35 cm
- Weight: ~6.2 kg
Portability: The modular design allowed the USV to be assembled/disassembled on-site, enhancing deployability.
2. Control & Navigation Systems
Controller: Pixhawk 2.4.8 (running ArduRover firmware)
Ground Control Station (GCS):
- Mission Planner Software on a laptop
- FlySky FS-i6X transmitter for manual and autopilot modes
- Telemetry module for real-time communication
Navigation:
- GPS Module (M8N with Compass) providing accurate positioning
- Waypoint Missions: Pre-programmed routes (Parallel & Expanding Square) for autonomous SAR coverage
Failsafe Features: Return-to-Launch (RTL) in case of signal loss
3. Underwater Camera System
- FPV Camera with Gimbal housed in a 3D-printed waterproof dome.
- Real-time Video Transmission to the operator via a 5.8G FPV Monitor (4.3-inch LCD).
- Control: Remote adjustment of tilt and pan for flexible victim/hazard detection.
- Testing: Verified waterproofing, smooth gimbal movement, and stable live feed.
4. Power & Propulsion
Power System
- Batteries: Dual 3S 7100mAh LiPo batteries connected in parallel
- Total Capacity: 14,200mAh
- Endurance: ~140 minutes operation time
Propulsion
- Thrusters: Hobbyocean Underwater Thrusters (860KV)
- Steering: Skid steering (precise control by varying left/right thrust)
- ESCs: Two 40A Brushless Bidirectional ESCs housed in sealed compartments
- Top Speed: 7.24 km/h
5. Software & Firmware
Firmware: Utilized ArduRover (part of the ArduPilot suite) for autonomous navigation and control.
Mission Planning: Developed and executed systematic search patterns, including Parallel and Expanding Square routes, to maximize coverage during SAR operations.
Telemetry & Monitoring: Real-time data streams included GPS location, speed, battery levels, and live camera feed, all accessible via the Ground Control Station.
Data Logging: All telemetry and mission data were recorded for post-operation review and performance analysis.
Testing & Results
Field Trials
Testing was conducted in the Bristol River due to limited access to pool facilities. For safety, a rope was attached to the USV during initial trials to prevent loss.
Mechanical Evaluation
- Buoyancy: Supported its own weight (6.2 kg) plus an additional payload of approximately 7.8 kg.
- Manoeuvrability: Demonstrated precise control, including the ability to rotate in place.
- Portability: Easily transported and deployed by a single operator.
Performance Assessment
- Battery Endurance: Achieved an operational time of approximately 140 minutes.
- GPS Connectivity: Maintained connections with 9–19 satellites, ensuring accurate navigation.
- Speed: Reached a top speed of 7.24 km/h.
- Camera System: Provided stable, real-time underwater video without leaks.
Autonomous Mission Trials
- Parallel Pattern: Enabled efficient scanning of large open areas.
- Expanding Square Pattern: Proved effective for locating targets near a specific point.
Project Cost Breakdown
| Component | Quantity | Price (£) |
|---|---|---|
| Pixhawk 2.4.8 | 1 | 78 |
| M8N GPS + Compass | 1 | 15 |
| 3S 7100mAh LiPo Battery | 2 | 94 |
| Underwater Thrusters | 2 | 84 |
| ESC 40A | 2 | 40 |
| FPV Camera + Transmitter | 1 | 15 |
| Video Receiver + Screen | 1 | 20 |
| Telemetry Module | 1 | 15 |
| Servo MG90S | 2 | 6 |
| Power Module | 1 | 4 |
| Power Distribution Board | 1 | 5 |
| Buzzer | 1 | 3 |
| Switch | 1 | 2 |
| Foam Boards | 4 | 8 |
| Acrylic Pipes (25cm & 20cm) | 4 | 6 |
| Small Containers | 2 | 6 |
| Large Container | 1 | 7 |
| Camera Dome | 1 | 17.5 |
| Total | 425.50 |
Technologies Used
- Hardware: Pixhawk 2.4.8, Hobbyocean Thrusters, FPV Camera, GPS Module, LiPo Batteries
- Software: Mission Planner, ArduRover Firmware
- Design Tools: SolidWorks, 3D Printing, Laser Cutting
- Budgeting Tools: Excel (for Gantt chart & cost tracking)
Visuals
