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This report describes a new design of an autogenous mobile system. A Duffing oscillation with a cubic spring, which is excited by an impulse periodic force, is utilized to drive the whole system without impacts. Backward and forward motion can be achieved by applying a proper direction of the excitation force. The ability of bi-directional motion of the system has been experimentally validated. The proposed mechanism can be utilized in different scales of mobile systems without using external mechanisms such as legs or wheels.