Development and Demonstration of Motion Stabilized Platform for Offshore Wind Observations

Abstract Our research group proposed a fundamental concept for a motion stabilized platform for a Floating LiDAR System (FLS) and validated the concept through numerical simulations. This paper discusses the development of a prototype motion stabilized platform (MSP) and its motion reduction performances. The platform has a two-axis gimbal structure with a vertical LiDAR and a counterweight set on the inner gimbal stage. The position of the counterweight is adjusted so that the restoring moment on the inner gimbal system becomes zero, that is the height of the center of gravity of the inner gimbal system coincides with the rotation axes. The control torque for each axis is generated by an AC servo motor and these torque were estimated based on the skyhook damper and skyhook spring theories. Motions of a FLS in waves were simulated using the stewart platform which is a type of parallel manipulator that has six prismatic actuators. From the demonstration tests, assuming that the distribution of rotation angles expressed in Euler angles of the MSP follows the Gaussian distribution, it is confirmed that the 95 % confidence intervals for the rotation angles of the MSP were less than 1.0° when those intervals for rotation angles expressed in Euler angles of the FLS were less than 4.0°. It is also confirmed that rotation angles of the MSP were reduced to about one-fourth of rotation angles of the FLS when the platform experiences large waves.