Torsional vibration suppression by wave-absorption control with imaginary system

We discuss vibration suppression in a lumped torsional system using wave-absorption control with online computation of an imaginary wave-propagation system similar to the real-controlled system. The basic concept of control was presented elsewhere for a multiple pendulum system to suppress free vibrations. We studied the suppression of forced vibration by a wave-absorption control for a lumped torsional system. Results confirmed that the proposed method works well on forced vibrations as on free vibrations. Initialization, setting amplitudes and velocities to zero, of the imaginary system for forced vibration control influences controlled amplitudes more than that for free vibration because vibration energy invariably comes in the system. Using numerical simulation, we studied initializations. Theoretical analysis on wave propagation in a lumped system has shown that smaller mass and larger spring stiffness of an imaginary system absorb vibration energy better, giving the optimum design for the imaginary system. Experiments are conducted for one-, two-, and three-degrees-of-freedom systems.