Study On Active Isolation Technology For Diesel Two-stage Vibration Isolation Mounting

Basing on diesel two-stage hydraulic active vibration isolation mounting, control strategy, actuator and control object in active vibration control technology are deeply investigated in this dissertation, and the main work is described as follows:For the current mounting, nonlinearity of hydraulic actuator, which results in heavy nonlinearity of the secondary path, is the dominant factor to influence the effectiveness of active vibration isolation. After intensive studying on nonlinearity of the secondary path is implemented, model reference adaptive inverse control with pre-compensator (PCMRAIC) strategy is proposed, and linearization process of the secondary path of the current mounting is realized in this dissertation.Nonlinear system identification of the secondary path is one of the key parts in PCMRAIC strategy. After intensive studying on nonlinear system identification theory and method, frequency-domain nonlinear order-uncoupled (FDNOU) system identification method is proposed in this dissertation. This nonlinear system identification method is employed on the current mounting, and then system parameter of the secondary path is evaluated by steady sweep tests.Combining PCMRAIC strategy and adaptive notch filter algorithm, the improved adaptive notch filter algorithm is proposed and applied to active vibration control experimental research of the current mounting in this dissertation. Results of active vibration control experiment show that: under each working rotation speed of diesel engine, nonlinearity of the secondary path is weakened by employing the improved adaptive notch filter algorithm, harmonic frequency response is effectively suppressed while obtaining 20～35dB attenuation on fundamental frequency vibration, vibrations of four mounting-feet are balanced, so a good vibration isolation performance on the whole mounting is consequently obtained. To the current mounting, the following investigations are conducted: 1. characteristics of active and passive vibration isolation systems are analyzed by presenting linear system energy modeling, numerical simulation and its corresponding experiment; 2. some influence factors, e.g. phase-frequency characteristic of the secondary path, linearization reference model, identification model of the secondary path and pre-compensator model etc., are discussed in detail by considering the improved adaptive notch filter algorithm and its experimental results. The results show that: better vibration isolation performance at fundamental frequency of the mounting is obtained by the improved adaptive notch filter algorithm when fully considering each influence factor.