Modeling and Control of a Fully Actuated Unmanned Surface Vehicle

Kılınç, Mustafa
This thesis presents a mathematical model and control strategies for a fully actuated unmanned surface vehicle (USV). We aim to control the body velocity of the robot with a model-based time-varying linear quadratic regulator (TV-LQR) and operate the control algorithm from the ground station of the robot with low-frequency remote communication signals. As TV-LQR computes the optimal control policy by considering a mathematical model, the 3 degrees of freedom (3DoF) decoupled model is derived from the Newton-Euler equations and Fossen’s low-speed USV assumptions. MATLAB’s constrained nonlinear optimization function estimates the parameters of this model by using experimental data. The k-fold cross-validation method is implemented to see the distributions of the parameters between randomly chosen validation datasets. The conventional PI control algorithm is chosen as a baseline method for comparison with our controller approach. The main contributions of this study are developing a mathematical model of a novel USV and performance analysis of the model-based TV-LQR controller in actual experiments. Results show that fully actuated velocity control with TV-LQR and quadratic programming based control allocation improves the robot’s velocity tracking performances in each DoF. Also, quadratic programming allocates the robot’s actuator inputs according to the thrusters’ physical limits and optimizes power consumption during the control allocation.
Citation Formats
M. Kılınç, “Modeling and Control of a Fully Actuated Unmanned Surface Vehicle,” M.S. - Master of Science, Middle East Technical University, 2023.