Motion Evaluation of Floating Point Absorber-type Wave Energy Converter by Kane's Equation

In this paper, we derive the equations of longitudinal motion for a floating point absorber type wave energy converter (FPAWEC) by Kane's equation. Since FPAWECs have a nonholonomic constraint, we selected Kane's equation which is based on the principle of virtual power. The time-domain motion equations of the FPAWEC with several control strategies were developed and its motion evaluations were conducted in regular and irregular waves. The motion evaluation results were reasonably consistent with the measured ones, both in regular and irregular waves. The dominant pitch motion in irregular waves was observed around pitch natural frequency. Using the derived equations, we investigated the pitch moment components and found that the pitch moment on the float had the largest contributions to pitching motion with the pitch natural frequency.