Design and implementation of a low cost, pump-based, depth control of a small robotic fish

Recently, there has been growing interest in biomimetic underwater vehicles. To exploit the full workspace of this kind of vehicles, depth control is needed and plays a critical role. Although depth control for large vehicles such as submarines has been addressed, this issue for low-cost, small-scale underwater vehicles has not received attention. In this paper, the depth control of a small robotic fish is studied, and implemented with the use of a small dc pump. The depth system dynamics are developed and limitations rising from the low-cost, small-scale actuators and sensors are described. A controller with limited feedback is designed, implemented and validated both by simulations and experiments. It is expected that this controller will add an important dimension to depth control of low-cost, energy-efficient small underwater vehicles.