Response characteristics and maneuverability of a small twin screw displacement hull vessel in seas

Abstract

This paper presents the response characteristics and maneuverability of a small twin screw displacement hull vessel quantified through a series of full-scale trials conducted in different environmental conditions. The 20-m test vessel is instrumented with actuator, environmental, and motion sensors. Several different maneuvers are performed at different speeds, including steady maneuvers with constant control input and transient maneuvers with varied control input to quantify and characterize the response of small vessels to aid in automatic controller and simulation development. Straight-line runs are performed in both forward and reverse over the entire operating range of the test vessel to investigate the relationship between throttle position, RPM, and surge velocity. Turning maneuvers are conducted over the achievable rudder deflection range to quantify the vessels turning radius and the relationships with surge, sway, and rotational speed. Other maneuvers include stationary rotation with the engines operating in opposite gears, and transient tests when the vessel is rapidly accelerated and decelerated. These actuator tests not only quantify the response of the actuators, but also set guidelines for the minimum dwell times that should be observed when shifting gears. These data found using a comprehensive sensor suite provide valuable benchmarks for several maneuvers that can be used for simulation validation and the actuator response information provides valuable set points and performance characteristics/limitations that should be considered in control development. The data from these tests were repeatable from run to run and thus, with sufficient instruments, at sea maneuvers can be used to collect a comprehensive set of data that can expand on data collected in tow tests.