• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.497-502
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• 2008

In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of secondary sound source in duct ANC system. Automobile exhaust noise was recorded at 800rpm. 3500rpm and 5000rpm of a diesel engine. Directions of loudspeaker(second sound source) can be exchanged to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for experimentation. DSP board with TMS320C6416 chip of Texas Instrument Co used to control adaptive ANC system. This ANC system is based on the single-channel FxLMS algorithm. In experiment result, when the loud speaker direction was $150^{\circ}$, the attenuation effect showed largely. In case of $90^{\circ}$ duct, the noise was a little increased. In case of $30^{\circ}$ duct, the noise was a little increased or decreased according to the frequency range and the sound pressure(dB) of exhaust noise to comply with engine rpm.

• 한국소음진동공학회논문집
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• 제25권9호
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• pp.628-636
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• 2015

In this study, theoretical and experimental analyses were performed for creating and moving the zone of quiet(ZoQ) to the ear location of a sitter by using active sound control technique. As the ZoQ is actively created at the location of the error microphone basically with an active sound control system using an algorithm such as the filtered-x least mean square(FxLMS), the virtual microphone control(VMC) method was considered to move the location of the ZoQ to around the sitter`s ear. A chair system with microphones and loudspeakers on both sides was manufactured for the experiment and thus an active headrest against the swept narrowband noise as the primary noise was implemented with a real-time controller in which the VMC algorithm was embedded. After the control experiment with and without the VMC method, the location variation of the ZoQ by analyzing the error signals measured by the error and the virtual microphones. Therefore, it is observed that the FxLMS with the VMC technique can provide the re-location of the ZoQ from the error microphone location to the virtual microphone location. Also it is found that the amount of the attenuation difference between the two locations was small.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.251-260
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• 2009

In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of canceling speaker in ANC system. Automobile exhaust noise was recorded at 800 rpm, 3500 rpm and 5000 rpm of a diesel engine. Directions of canceling speaker can be set to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for the experimentation. DSP board with TMS320C6416 chip of Texas Instrument Co. used to control the ANC system. The algorithm of this ANC system applied the Filtered-x-LMS algorithm that is modified to compensate for a property of DSP input signal and the secondary-path effect. As an experiment result, the direction of canceling speaker was proved to influence the reduction effect of noise. The $150^{\circ}$ duct in the attenuation effect of noise showed a better result than the $90^{\circ}$ or $30^{\circ}$ duct.

• 한국방재안전학회논문집
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• 제16권3호
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• pp.45-56
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• 2023

본 연구에서는 능동소음제어(ANC) 기술을 층간소음 분야에 적용하기 위하여 40~500 Hz 대역의 중량충격음을 제어하기 위한 ANC 시스템을 구성하였다. ANC 시스템에는 Fx-LMS 알고리즘 기반의 적응형 필터를 활용한 피드포워드 방식의 제어기술을 도입하였다. ANC 시스템 설정을 위해 가상 시뮬레이션을 통해 ANC를 구성하는 변수 연구를 실시하였고, 이를 통해 최적 필터와 시스템 배치 방법을 정립하였다. 또한 본 연구에는 개발된 ANC 시스템을 한국건설생활시험연구원(KCL)의 층간소음 시험실에 설치한 후 표준시험방법에 따라 ANC 시스템 구동 전후 4 dB의 층간소음 저감효과를 확인하였다. 시험결과를 통해 본 연구에서 개발한 ANC 시스템이 중량충격음에 대한 등급 기준을 한 단계를 상향시킬 수 있는 수준의 효과가 있음을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.115-119
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• 2011

Instead of very expensive sound record and professional measurement microphones the low cost Surface Mounted Device (SMD) microphones are proposed for practical barrier ANC system. FRF of the microphones and theirs sensitivity to the wind interferences are evaluated in semi anechoic chamber. The improvement of feedforward algorithm noise reduction index was evaluated based on measured coherence function between tested SMD and reference microphone. Test was performed at various wind speed from 1 m/s to 5 m/s.

• 대한임베디드공학회논문지
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• 제16권6호
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• pp.241-246
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• 2021

In this paper, we developed the evaluation system for the active noise control so that the algorithms can be easily evaluated in real-time on the system. We implemented the active noise controller based on a single-chip with only additional op-amps for signal conditioning because the TMS320C280049 MCU includes almost all necessary peripherals for the active noise controller. Due to the difficulty in testing algorithms on embedded-type hardware unlike in computer simulation, we also developed GUI-based evaluation software which makes it simple to test algorithms on the hardware. Using the GUI software, we can optimize the parameters of the algorithms with ease in a specific noise environment because the parameters can be adjusted in real-time when the algorithm is running on the hardware.

• 한국도로학회논문집
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• 제15권6호
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• pp.41-47
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• 2013

PURPOSES : The purpose of this study is about noise which is generated from roads and is consist of irregular frequency variation from low frequency to various band. The existing methods of noise reduction are sound barrier that uses insulation material and absorbing material or have applied passive technology of noise reduction by devices. The total frequency band is needed to apply active noise control. METHODS : In this study applies to the field of road traffic environment, signal processing controller and various analog signal input/output, the amplifier module is based on parallel-core embedded processor designed. DSP performs the control algorithm of the road traffic noise. Noise sources in the open space performance of evaluation were applied. In this study, controller of active signal processor was designed based on the module of audio input/output and main controller of embedded process. The controller of active signal processor operates noise reduction algorithm and performance tests of noise reduction in inside and outside environment were executed. RESULTS : The signal processing controller with OMAP-L137 parallel-core processors as the center, DSP processors in the active control operations dealt with quickly. To maximize the operation speed of an object and ARM processor is external function keys and display for functions and evaluating the performance management system was designed for the purpose of the interface. Therefore the reduction of road traffic noise has established an electronic controller-based noise reduction. CONCLUSIONS : It is shown that noise reduction is effective in the case of pour tonal sound and complex tonal sound below 500Hz by appling to Fx-LMS.

• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.

• Smart Structures and Systems
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• 제25권5호
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• pp.559-567
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• 2020

Vibration at the tip of various flexible manipulators may affect their operation accuracy and work efficiency. To suppress such vibrations, the feasibility of using MFC actuators and sensors is investigated in this paper. Considering the convergence of the famous filtered-x least mean square (FXLMS) algorithm could not be guaranteed while it is employed for vibration suppression of plants with varying secondary path, this paper proposes a new multiple model switching adaptive control algorithm to implement the real time active vibration suppression tests with a new multiple switching strategy. The new switching strategy is based on a cost function with reconstructed error signal and disturbance signal instead of the error signal from the error sensor. And from a robustness perspective, a new variable step-size sign algorithm (VSSA) based FXLMS algorithm is proposed to improve the convergence rate. A cantilever beam with varying tip mass is employed as flexible manipulator model. MFC layers are attached on both sides of it as sensors and actuators. A co-simulation platform was built using ADAMS and MATLAB to test the feasibility of the proposed algorithms. And an experimental platform was constructed to verify the effectiveness of MFC actuators and sensors and the real-time vibration control performance. Simulation and experiment results show that the proposed FXLMS algorithm based multiple model adaptive control approach has good convergence performance under varying load conditions for the flexible cantilever beam, and the proposed FX-VSSA-LMS algorithm based multiple model adaptive control algorithm has the best vibration suppression performance.

• 한국항공우주학회지
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• 제48권6호
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• pp.443-453
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• 2020

대표적인 기동 헬리콥터인 UH-60A의 기체 진동응답을 감소시키고자 능동 진동 제어 시스템(Active Vibration Control System, AVCS)을 이용한 시뮬레이션 연구를 수행하였다. 로터 진동 하중, 기체 구조 동역학 모델링, 진동응답 해석 및 진동 제어 시뮬레이션 연구를 수행하기 위하여 DYMORE II, NDARC, MSC.NASTRAN 및 MATLAB Simulink 등의 다양한 해석, 설계 및 제어 프로그램들을 함께 사용하였다. 5개의 CRFG와 7개의 가속도계로 이루어진 Multi Input Multi Output(MIMO) 모델을 AVCS 시뮬레이션 연구에 이용하였다. 본 시뮬레이션 연구를 통하여 진동이 극심한 158knots의 비행속도에서 UH-60A의 주요 위치(조종석, 로터와 기체의 접합부, 중앙 승객실 및 후방 승객실) 위치에서 AVCS의 사용으로 인하여 4/rev 기체 진동응답이 25.14~96.05%만큼 감소될 수 있었다.