Stability Analysis of Open-loop Stiffness Control to Suppress Self-excited Vibrations

We present stability investigations on vibration cancelling employing three different types of variable-stiffness actuators. A two-mass system is considered, with a base mass attached to the ground and a top mass connected to the base mass. The top mass is subject to self-excitation forces. The stiffness of an actuator connecting the base mass and the ground may change with time, according to a predetermined control frequency, for cancelling vibrations. Numerical simulation is employed as the basic tool to investigate the system and to carry out parameter studies. The stability of the system is determined by calculating the eigenvalues of the state transition matrix. Robustness of the proposed methods for vibration cancelling is discussed with respect to various aspects.