A control scheme for 360°thrust vectoring of cycloidal propellers with forward speed. (1st April 2022) - Desai, Manavendra
Abstract: This paper introduces a control scheme to vector thrust in marine cycloidal propellers with non-zero forward speed, despite the presence of measurement noise and current-like disturbances. Cycloidal propellers utilize 360° thrust-vectoring to provide agile maneuvering to surface vessels like tugboats and double ended ferries, but have yet to be utilized in present-day unmanned and autonomous marine vehicles. This work strategizes a low-level cycloidal propeller controller to track a reference thrust magnitude and direction for use in high-level control of underwater vehicles. Unlike previous work that assumes zero inflow-speed, the propeller-shaft speed and propeller-blade phase are hydrodynamically coupled in cases with non-zero inflow. The incorporation of this coupling enables thrust-tracking over varying advance-speeds necessary for propulsion and maneuvering of unmanned and autonomous underwater vehicles. A torque controller for screw propellers is extended for thrust-tracking in cycloidal propellers. A propeller-phase control loop is added and the resultant controller is verified through simulations for 360° thrust vectoring of cycloidal propellers in currents and varying cruise speeds. This low-level controller will enable use of cycloidal propellers for high maneuverability and thrust-augmentation in applications like station-keeping, seakeeping, maneuvering, and teaming of unmanned and autonomous marine vehicles in complex marine environments like surf zones and restricted waters. Highlights: A novel control scheme to vector thrust of marine cycloidal propellers is presented. Hydrodynamic coupling between propeller-speed and phase angle is highlighted. Measurement noise and disturbances like water currents are considered. High maneuverability and high control authority of underwater vehicles in restricted waters can be achieved.