Fig. 7
Active control block diagram. The pitch stabilization control flow is shown in this figure. The control plant G consists of the whole structure of buoy together with stabilization mechanism. \(\theta\) and \(\theta _d\) are the observed and the desired pitch angle (i.e., zero degree) of the buoy, respectively. The controller C gets the pitch deviation \(\theta _e\) and sends the proper linear displacement r of the slider to the G. Wave induced external forces are input as a distubance d to the system