Semi-Active Vibration Control Based on Switched Piezoelectric Transducers

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A distributed and low-order GPS/SINS algorithm of flight parameters estimation for unmanned vehicle

A distributed, low-order and highly efficient strapdown navigation algorithm is developed to estimate the real flight parameters for flight control system. Firstly, the attitude estimation Kalman filter is designed according to the relationship between angular and angular rate. Then, the measured angular rate is compensated by solving the drift noise of gyro. Furthermore, the accuracy of attitude is improved by compensating the accelerometer of the rigid body from differential velocity of GPS. Secondly, the improved attitude is used as an input into the filter algorithms of velocity and position by using the concept of distributed Kalman filter, which reducing the order of Kalman filter effectively. The velocity and position filter algorithms, which provide smooth feedback parameters for control system, are developed based on the rigid body dynamic equations and GPS parameters. Finally, the numerical simulation indicates that the attitude provided by attitude Kalman filter is of high accuracy in flight condition, and the performance of the attitude velocity and position algorithms are verified by flight tests of a small unmanned tiltrotor

Optimal Control of Pretwisted Rotating Thin-Walled Beams via Piezoelectrically Induced Couplings

Problems related to mathematical modeling and optimal active control of pretwisted adaptive blade are considered. The blade is modeled as a rotating thin-walled composite beam embedded with anisotropic piezo-composite layers accounting for nonclassical effects, such as transverse shear and warping inhibitions. The linear-quadratic-regulator feedback control strategy is adopted to study the tailoring of piezo-actuators on vibration suppression. Control authority of piezoelectrically induced transverse shear and bending coupling is highlighted. Tailoring studies using the present model reveal that piezoelectrically induced transverse shear plays an important role on control effectiveness. In addition, the relations between the control authority and the elastic couplings, piezoelectrically induced actuation couplings, pretwist angle, and size and position of piezo-actuators are investigated

Measurement Technique and Result Analysis of Helicopter Rotor Blade Structural Vibration Load

The measurement of helicopter rotor blade structural load amid flight has always been the difficulty in flight test. In this paper, the principle of the existing blade structural load measurement method (electrical measurement method) was analyzed, and the problem of physical decoupling in the use of this method was expounded. As a weak signal measurement, the electrical measurement method also has electromagnetic interference problems, which will affect the flight test period of blade structural load measurement. Therefore, a numerical decoupling measurement method based on fiber Bragg grating (FBG) was proposed. Then, the new method was applied and verified in the load equation modeling test and the flight test under the real atmospheric environment was carried out. Through comparing and analyzing the measured data of the new method and the electrical measurement one, the correctness of the FBG data decoupling method was validated. The results indicate that the method proposed in this paper can effectively improve the efficiency of blade load equation modeling engineering and has good application value