Semi-Active Vibration Control Based On MR Damper

The power machine is an important vibration source for submarine and low frequency and wide band vibration may be induced. Passive isolation system has been widely used to reduce the vibration intensity transferred to the base. Low-frequency Isolators (Such as air spring, which≤2Hz) has been developed to improve the isolation effect. But such low-frequency isolation systems may lead to large displacement when resonance and shock input occur. Big damping ratio can greatly inhibit the resonance response and low frequency vibration transmission, however it will deteriorate high frequency isolation effect.The MR(magneto-rheological) damper is a novel device which offer controllable damping force through functional material . It has advantages of rapid response, large output, infinitely variable force and reversible state inversion. Using the MRD, the damping ratio of the system can be updated in real-time to cope with resonance and low frequency vibration, and make sure the system reach a good isolation effect for full band.Based on the test results of MR damper characteristics, a double sigmoid model is built for MRD, test results show that the model is accurate and reliable to describe the MRD characteristics for different drive currents. An algorithm for deducing drive current based on the model was proposed to ensure the real-time control of the MR Force.A dynamic model for two-stage vibration isolation system is set up, the frequency response function is deduced by impedance analysis method and the influence of damping ration on vibration transmissibility and relative displacement is researched.The fuzzy control algorithm is investigated and a semi-active vibration controller is designed. Simulations are implemented in Matlab software environment to investigate the vibration control effect of the algorithm under different vibration excitations. Simulation results showed that the algorithm can reduce the resonance response and improve the isolation effect of random vibration and vibration in the range of 1st and 2nd frequency.Based on DSP hardware, the semi-active vibration control program is designed, using the CCS software. The controller is consisted of signal measuring and conditioning module, data sampling module, fuzzy control algorithm and signal output module. Experiment is carried out on a two-stage test bench and control effects for vibration of different frequency is analyzed by measuring the acceleration on lower course.