Based on multi-degree-of-freedom impact oscillators with clearances ,
equations for the system away from impact and complicated impact situation and
corresponding impact governing equations, with Runge-Kutta method to numerical
simulation, the paper reveals that systems have complex chaotic motions. Theoretical
analysis shows that delay feedback control can control system validity, phase plane
portrait and time series also display that this method can control chaotic impact
motions operative to periodic orbits.