Nonlinear Attitude Control of a Spherical Underwater Vehicle

Area of Science:

• Robotics and Control Systems
• Ocean Engineering
• Autonomous Underwater Vehicles (AUVs)

Background:

• Spherical underwater vehicles offer unique maneuverability advantages.
• Effective attitude control is crucial for AUV navigation and task execution.
• Existing control methods may lack precision and responsiveness for complex maneuvers.

Purpose of the Study:

• To design, implement, and test a State Feedback Linearization (FL) based attitude control system for a prototype spherical underwater vehicle.
• To evaluate the performance of the FL controller against a baseline Proportional-Integral-Derivative (PID) controller.
• To assess the vehicle's mechanical design, onboard electronics, and dynamic model.

Main Methods:

• Development of a high-fidelity dynamic model for a 6-DOF spherical underwater vehicle.
• Implementation of a State Feedback Linearization (FL) control algorithm.
• Experimental comparison of FL and PID controllers in a controlled environment.

Main Results:

• Both FL and PID controllers successfully executed specified maneuvers.
• The FL controller exhibited significantly improved precision compared to the PID controller.
• The FL controller demonstrated a superior time response, completing maneuvers faster.

Conclusions:

• State Feedback Linearization (FL) provides a highly effective attitude control solution for spherical underwater vehicles.
• The proposed FL system surpasses traditional PID control in terms of precision and responsiveness.
• The novel pendulum-based passive pitch control mechanism and manifold thruster configuration contribute to the vehicle's maneuverability.