Non-linear response of a self-sustained electromechanical seismographs to fifth resonance excitations and chaos control

In this paper, the problem of dynamics and chaos control of an electromechanical instrument which is used to record the motion of earth during and earthquake is studied. The amplitude of the fifth sub- and super-harmonic oscillations for the resonant states are obtained and discussed using the multiples time scales method. It is found that chaotic and periodic orbits of the system depend strongly of the value of the damping. The suppression of chaos using small amplitude damping signals is also investigated and the condition under which chaos suppression is possible is derived. Simulation results are presented to confirm analytical process.