This project responds to the growing concern over pollution in UK rivers by developing a remotely operated vehicle (ROV) capable of navigating river environments to deliver sensors for water pollution detection. The system was designed, machined, and assembled entirely by our team of 4 over a six-month iterative CDIO development cycle, with a particular focus on creating a compact, modular and maintainable prototype

The Problem
Static river monitoring is expensive, inaccurate, and inconsistently deployed. ROVs are common in marine environments but far less adapted to rivers. Challenges like debris, signal loss underwater, and cost leave a gap that this project aimed to address.

Our Solution
We designed and built an aluminium-shelled ROV featuring modular sensor ports, 3D printed propellers, and a unique buoy-based communications relay to bypass underwater radio limitations. The system is split into three tiers: a wireless handheld controller, a floating communications buoy, and the ROV itself.

Mechanical Design
The ROV frame was CNC machined from aluminium, with TIG-welded ports, threaded endcaps, and custom skids for riverbed contact. We opted for a three-part ballast tank system and sealed bearings with rotary shaft seals. CFD simulations helped refine propeller geometry and confirmed the thrust needed to overcome typical river currents. The buoy, controller and tank was 3d printed out of PETG with special care taken to ensure water tightness.

Control & Comms
The ROV connects to a floating buoy using SPI over a short tether. The buoy then relays commands and sensor data wirelessly to the handheld controller via peer-to-peer Wi-Fi. We designed a wire retraction system controlled by a stepper motor to keep the tether short and tensioned. Custom microcontroller firmware enables live streaming from a 3MP SPI camera and real-time sensor feedback.

Sensor Systems
We integrated a turbidity sensor and ultrasonic depth sensor with modular mounts for easy replacement. An onboard accelerometer assists with orientation tracking. While the ballast tank system wasn't viable in the final version due to sealing issues, the modular electronics allowed full testing of all other systems. As well as this a front facing camera was implemented that could be streamed to either the controller or any wi-fi capable device.

Outcome & Future Work
The prototype is a functioning proof-of-concept that can be piloted wirelessly in water and return accurate environmental readings. Future development will focus on PCB miniaturisation, improved sealing, and implementing autonomous behaviours. The modular sensor interface proved a particular success, allowing adaptability for a wide range of monitoring tasks.

We presented our idea at an engineering event where people attending could control the ROV in a pool we set up. At this event we won the prize for best group presentation.