Classified by incentive control:
1. Free vibration: The vibration that the system is no longer subject to external excitation after initial excitation.
2. Forced vibration: The vibration of the system under the excitation of external control.
3. Self-excited vibration: The vibration of the system under the excitation of its own control.
4. Participation vibration: The vibration excited by the change of the system’s own parameters.