Vahid Vaziri

Nonlinear Dynamics of Pendulums System for Energy Harvesting

In this paper dynamics of a parametric pendulums system operating in rotational regime has been investigated with a view of energy harvesting. The main idea is based on the conversion of the oscillatory motion of the oscillatory motion into rotation of pendulums [1]. Numerical, analytical and experimental studies have been undertaken on a parametric pendulum and a pendulum excited by a planar motion. They suggest the rotational motion is persisting and occurs for a large range of frequencies and excitation amplitudes, which are the main control parameters. These investigations reinforce the viability of this new concept of the energy conversion. A system of two pendulums has been modelled and analysed. Specifically, the dynamics of the parametric pendulums systems has been investigated numerically and experimentally focusing on synchronized rotational solutions. The target state is a synchronized counter rotation of both pendulums. A control strategy aiming to initiate and maintain the desired rotational responses, has been developed and verified numerically and experimentally.

Experimental bifurcation control of a parametric pendulum

The aim of the study is to maintain the desired period-1 rotation of the parametric pendulum over a wide range of the excitation parameters. Here the Time-Delayed Feedback control method is employed to suppress those bifurcations, which lead to loss of stability of the desired rotational motion. First, the nonlinear dynamic analysis is carried out numerically for the system without control. Specifically, bifurcation diagrams and basins of attractions are computed showing co-existence of oscillatory and rotary attractors. Then numerical bifurcation diagrams are experimentally validated for a typical set of the system parameters giving undesired bifurcations. Finally, the control has been implemented and investigated both numerically and experimentally showing a good qualitative agreement.

Dynamics, Synchronization and Control of Parametric Pendulums

In this work the dynamics and synchronization of the coupled parametric pendulums system is examined with a view to its application for wave energy extraction. The system consisting of two parametric pendulums on a common support has been modeled and its response studied numerically, with a main focus on synchronized rotation. Different methods of controlling the response the pendulums have been introduced and compared. Numerical results have been verified in experimental studies.