Autonomous Roll Control in a Cross-Form Rudder Submarine Using PID Controllers

Thesis (Master's)--University of Washington, 2020When traveling on a flat, two-dimensional plane, an automobile can be considered a rigid body. However, in a three-dimensional plane, the trajectory of an underwater vehicle is more analogous to those of aircrafts. The addition of an extra dimension makes maneuverability more challenging, necessitating proper fuel consumption. Also, the third dimension creates an induced roll while turning underwater in transit from point to point, which disturbs vehicle orientation. Serving as this project’s motivation, these conditions describe inefficiencies in the prevailing modus operandi. By controlling the watercraft’s roll, the pilot’s controls can be simplified, while also decreasing distance needed to reach the end point. This thesis describes the development of a cost-efficient standalone system, capable of both position and orientation tracking, as well as autonomous port and starboard control of a human-powered submarine (HPS). The innovation is that the primary inputs to this controller are obtained from a microcontroller outputting data from the vehicle and calculated on a PID controller using live stream data. The customized PID controller developed through the means described in this thesis utilizes a cascade control architecture to achieve horizontal stability and minimize roll motion