Dynamics of the N-pendulum and its application to a wave energy converter concept

Abstract

This paper considers a design of an N-pendulum, which represents a special case of a physical pendulum. The design of the N-pendulum not only allows uncoupling the natural frequency of the pendulum from its length, but also provides easy control of the frequency and torque. The proposed design is stimulated by the idea of developing a wave power take-off system based on the parametric pendulum. Different designs are being considered and their dynamic characteristics are investigated with respect to the feasibility of such an application. Due to the observed low frequency of ocean waves, the size of a heaving simple pendulum should span along unrealistic sizes in order to be parametrically resonant. Thus, the N-pendulum is considered and the configurations that would fulfill these frequency requirements are sought. Last, numerical simulation is conducted for an under development experimental rig aiming to test the functionality of the concept, modelling the response of the N-pendulum.