| 1 | Noise attenuation of frequency-modulated multi-rotor using sound field reproduction显示文摘Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control. | Xice XU Yang LU Mengxue SHAO Jiaxin LU | 2023 | Chinese Journal of Aeronautics2023，36，11： | 0 |
| 2 | 伺服机构故障下运载火箭控制分配方法研究显示文摘This paper investigates the servo mechanism reconfiguration and fault tolerance control issue for a launch vehicle.Firstly,the servo reconfiguration algorithm is considered as an optimization model,and commonly used optimization algorithms are analyzed and compared.An improved method based on Singular Value Decomposition(SVD)for solving the suboptimal solution of the direct assignment problem is proposed,being suitable for engineering application,while maintaining the advantages of existing algorithms.Theoretical analysis and simulation results confirm that the proposed method is able to provide the optimal reconfiguration strategy with higher computational efficiency.Finally,the numerical simulation of launch vehicle fault tolerance control fully verifies the feasibility and effectiveness of the improved method,which indicates that the method met the engineering application conditions. | HU Cunming ZHANG Weidong ZHOU Jing ZHANG Yifeng LI Guifang XU Xice | 2022 | Aerospace China2022，23，2： | 0 |
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