Underwater Glider (2017 - 2018)
This glider was developed as a hobby project to be a low cost and versatile underwater glider capable of extended missions of up to weeks at a time.
This project ended up winning Grand Prize of the international 2017 Hackaday Prize, resulting in $50,000, and a 3-month design residency at the Supplyframe DesignLab.
- Eagle PCB Design
- 3D Rapid Prototyping
- Contract PCB Fabrication
Why a glider?
Traditional unmanned underwater vehicles depend upon active propulsion, limiting their range and runtime, making them unsuitable for long duration monitoring missions. Underwater gliders incorporate a buoyancy engine to change the mass of the glider, allowing them to ascend and descend through the water. With power only being used to power the engine intermittently, gliders can typically run for weeks or months without recharging.
As underwater gliders travel slowly through the water, they disturb the surrounding water very little, allowing for accurate and reliable data recording. Underwater gliders are normally AUVs (Autonomous Underwater Vehicles) and can run a pre-determined route without requiring human interaction. Their low speeds and autonomy, combined with long battery life, make underwater gliders ideal for long duration, environmental monitoring missions, capable of recording dissolved gas levels, pH, temperature and optical sensing (for oceanic surveying and sealife recording).
For the glider to move, the buoyancy engine takes in water, increasing the density of the glider such that the glider becomes denser than the surrounding water, in turn causing the glider to descend. The hydrofoils ensure forward movement; the angle of attack can be altered to cause different glide characteristics. When at the bottom of the descent, the buoyancy engine expels the water, making the glider more buoyant, causing it to ascend and more forward again. For larger commercial glider's the buoyancy engine can either be achieved through a high-pressure ballast bag and pump, or using syringes to take in and expel water - this glider uses syringes to achieve a mass change of 900g (1.98lbs).
There is a mass within the glider that is used to control pitch and roll; mostly comprised of lithium-ion batteries and steel ballast, this is a substantial mass and has good control authority over the glider. To control glider pitch, a stepper motor moves this mass along the length of the glider, altering the center of mass and in turn, the pitch of the glider. The glider's roll is controlled similarly, the mass is bottom heavy so when the mass assembly is rotated via a planetary gearbox, the center of mass moves left or right slightly, this causes the glider to roll slightly, and there is a resulting curve whilst descending/ascending, allowing the glider to turn.