Design Of Helicopter Dynamic Vibration Absorber Based On Adaptive Control

Compared with other flight vehicle, more considerations of anti-vibration should be taken intothe process of helicopter development. A measure to suppress the vibration in helicopter is mountingseveral vibration absorbers to the fuselage. Although the passive vibration absorber has been widelyused for vibration reduction in helicopter, the active vibration absorber, of which the naturalfrequency can be regulated, is more applicable to the terrible vibration circumstance of helicopter.Because of the superior performance, it is worth researching on the active vibration absorber.The adaptive vibration absorber, proposed in this paper, tunes its natural frequency by adjustingthe value of the stiffness. The key problems of the thesis are the principle of stiffness adjustment, thedesign of the prototype of the absorber, and the establishment of the adaptive control law of frequencyregulation. In view of these problems, the thesis is mainly segmented in three areas as follows:1. The research on the principle of stiffness adjustmentThe relation between the stiffness and frequency of the absorber and the centroid distance of thenuts, which are constrained on a screw arbor, is deduced based on the assumption of smalldeformation. Furthermore, the more accurate relationship has been acquired neglecting theassumption of small deformation. In addition, the error between the approximate stiffness and precisestiffness, which have been obtained in previous steps, has been deduced and analyzed in the thesis.2. The design of the prototype of the absorberFirst of all, the parameters as mass, stiffness and damp are determined based on theory of fixedpoint. Secondly, the structural parameters of the absorber have been acquired according to designrequirements. In the next step, the prototype of the absorber is modeled in the software of ADAMS.Finally, the performance of the absorber is analyzed by using the software of ADAMS.3. The establishment of the adaptive control law of frequency regulation.The control strategy of frequency adjustment has been studied in this paper. Moreover, theadaptive control law of frequency regulation established based on the adaptive control theory. Theresults of simulation analysis show that the adaptive control system can ideally regulate the frequencyeven if the parameters of the controlled object changed greatly.