Controlling angular oscillations through mass reconfiguration: a variable length pendulum case

The control of angular oscillations or energy of a system through mass reconfiguration is examined using a variable length pendulum. Control is accomplished by sliding the end mass towards and away from the pivot as the pendulum oscillates. The resulting attenuation or amplification of the angular oscillations are explained using the Coriolis inertia force and by examining the energy variation during an oscillation cycle. Simple rules relating the sliding motion to the angular oscillations are proposed and assessed using numerical simulations. An equivalent viscous damping ratio is introduced to quantify the attenuation/amplification phenomena. Sliding motion profiles for achieving attenuation have been simulated with the results being discussed in detail.