  In this paper, we describe the development process of autonomous navigation
capabilities of a small cruise boat operating in a canal environment and
present the results of a field experiment conducted in the Pohang Canal, South
Korea. Nonlinear model predictive control (NMPC) was used for the online
trajectory planning and tracking control of the cruise boat in a narrow passage
in the canal. To consider the nonlinear characteristics of boat dynamics,
system identification was performed using experimental data from various test
maneuvers, such as acceleration-deceleration and zigzag trials. To efficiently
represent the obstacle structures in the canal environment, we parameterized
the canal walls as line segments with point cloud data, captured by an onboard
LiDAR sensor, and considered them as constraints for obstacle avoidance. The
proposed method was implemented in a single NMPC layer, and its real-world
performance was verified through experimental runs in the Pohang Canal.
