Adaptive Notch Filter Research Articles

Vibration Suppression of Multi-Stage-Blade AMB-Rotor Using Parallel Adaptive and Cascaded Multi-Frequency Notch Filters

Vibration Suppression of Multi-Stage-Blade AMB-Rotor Using Parallel Adaptive and Cascaded Multi-Frequency Notch Filters

Multi-domain awareness for compressed deepfake videos detection over social networks guided by common mechanisms between artifacts

The viral spread of massive deepfake videos over social networks has caused serious security problems. Despite the remarkable advancements achieved by existing deepfake detection algorithms, deepfake videos over social networks are inevitably influenced by compression factors. This causes deepfake detection performance to be limited by the following challenging issues: (a) interfering with compression artifacts, (b) loss of feature information, and (c) aliasing of feature distributions. In this paper, we analyze the common mechanism between compression artifacts and deepfake artifacts, revealing the structural similarity between them and providing a reliable theoretical basis for enhancing the robustness of deepfake detection models against compression. Firstly, based on the common mechanism between artifacts, we design a frequency domain adaptive notch filter to eliminate the interference of compression artifacts on specific frequency bands. Secondly, to reduce the sensitivity of deepfake detection models to unknown noise, we propose a spatial residual denoising strategy. Thirdly, to exploit the intrinsic correlation between feature vectors in the frequency domain branch and the spatial domain branch, we enhance deepfake features using an attention-based feature fusion method. Finally, we adopt a multi-task decision approach to enhance the discriminative power of the latent space representation of deepfakes, achieving deepfake detection with robustness against compression. Extensive experiments show that compared with the baseline methods, the detection performance of the proposed algorithm on compressed deepfake videos has been significantly improved. In particular, our model is resistant to various types of noise disturbances and can be easily combined with baseline detection models to improve their robustness.

Application of DMSFNN-COA technique for brand image design

Color plays a pivotal role in product design, as it can evoke emotional responses from users. Understanding these emotional needs is crucial for effective brand image design. This paper introduces a novel approach, the Brand Image Design using Deep Multi-Scale Fusion Neural Network optimized with Cheetah Optimization Algorithm (BID-DMSFNN-COA), for classifying product color brand images as “Stylish” and “Natural”. By leveraging deep learning techniques and optimization algorithms, the proposed method aims to enhance brand image accuracy and address existing challenges in product color trend forecasting research. Initially, data are collected from the Mnist Data Set. The data are then supplied into the pre-processing section. In the pre-processing segment, it removes the noise and enhances the input image utilizing master slave adaptive notch filter. The Deep Multi-Scale Fusion Neural Network optimized with cheetah optimization algorithm effectively classifies the product colour brand image as “Stylish” and “Natural”. Implemented on the MATLAB platform, the BID-DMSFNN-COA technique achieves remarkable accuracy rates of 99 % for both “Natural” and “Stylish” classifications. In comparison, existing methods such as BID-GNN, BID-ANN, and BID-CNN yield lower accuracy rates ranging from 65 % to 85 % for “Stylish” and 65 %–70 % for “Natural” product color brand image design. The simulation outcomes reveal the superior performance of the BID-DMSFNN-COA technique across various metrics including accuracy, F-score, precision, recall, sensitivity, specificity, and ROC analysis. Notably, the proposed method consistently outperforms existing approaches, providing higher values across all evaluation criteria. These findings underscore the effectiveness of the BID-DMSFNN-COA technique in enhancing brand image design through accurate product color classification.

Sufficient active control of uncertain low-frequency space micro-vibrations near measurement limit of acceleration sensors

High-precision payloads such as ultra-stable optical clocks for next-generation space missions are greatly sensitive to the low-frequency micro-vibrations induced by various flexible appendages equipped on the spacecraft. The frequencies of such micro-vibrations are uncertain and near the measurement limit of acceleration sensors, leading to insufficient vibration control performance of classical feedback control. To solve this problem, a hybrid control algorithm which combines PI controller and the filter-x least-mean-square (FxLMS) algorithm is proposed in the paper. In particular, a frequency estimation algorithm is designed for the active vibration control system to provide the reference signal. In the new system, the rough estimation of disturbance frequency is given by the adaptive notch filter. Then, the frequency is refined by Kalman filter and provided into the autoregressive model, which fine-tunes the estimated frequency and offers the reference signal for the hybrid PI-FxLMS algorithm. Finally, the experimental prototype of active vibration control system is developed and the proposed control algorithm is adopted. The experimental results demonstrate the effectiveness of the frequency estimation algorithm and further validate that the proposed hybrid PI-FxLMS algorithm can effectively suppress the low-frequency micro-vibrations near the measurement limit of acceleration sensors and with uncertain frequency.

Suppression of Multi-Harmonic Currents in the High-Speed Magnetically Suspended Motor Based on Adaptive Cascaded Notch Filters with Variable Phase Angle

Rotor imbalance is identified as one of the predominant vibration sources in high-speed magnetically suspended motors. Due to factors such as rotor machining accuracy errors and uneven material distribution, synchronous vibration interference is caused. Moreover, sensor runout generates harmonic currents, which are attributed to material irregularities and inhomogeneity in the roundness of the sensor detection surface. Harmonic currents can generate harmonic vibrational forces that are transmitted to the motor housing, jeopardizing control accuracy and the device’s operational lifespan. In order to achieve real-time reduction of harmonic currents at specified frequencies and improve the accuracy of harmonic suppression, this paper proposes an algorithm for variable phase angle filtering of an adaptive cascaded mode notch filter. This paper performed dynamic modeling and analysis of the magnetically suspended rotor system with rotor imbalance and verified the correctness of the dynamic model. Subsequently, the structure of an adaptive notch filter with variable phase angle is introduced, highlighting the capability to maintain stability by adjusting the compensatory phase of the system. By comparing the harmonic current suppression performance of cascaded and parallel mode notch filters, the cascaded method can better enhance the overall frequency selectivity, emphasizing its ability to adjust the compensation phase based on the phase angle of the input signal at different frequencies to maintain system stability. Simulation and experimental results show that harmonic currents can be successfully suppressed in the cascade mode, and the amplitude of the synchronous frequency current is reduced by 94.4[Formula: see text].

Active control method for fluid borne noise in aerospace fluid systems of variable operation statuses

In the fluid system of aerospace vehicles, the fluid-borne noise (FBN) may induce vibration and damage to components. The FBN may limit the performance of the entire onboard system. To achieve a stable active elimination for the FBN is not easy, for many variable operation statuses exist in practical systems, such as varying-frequency and varying-load status. In this work, an improved feed-forward active control method based on narrowband adaptive notch filters, with an online identification module, is proposed. The algorithm includes three adaptive filters: an adaptive notch filter for producing cancelling signal by using filtered-X least mean square (FXLMS) algorithm, one for online identification to model the real-time secondary path, and an error prediction filter for extracting the precise error for online identification. In the aircraft hydraulic system of high pressure, a so-called relief scheme, also known as the bypass structure, is used for the FNB, controlling an active control valve in the branched line to overflow the main fluid line. The system is modelled with software AMESim for the fluid part and Matlab for the control algorithm. Simulation results show that the control method can performance well in the situations of varying frequency and load. The test rig of a hydraulic system is established, which could change pump speed and fluid pressure. The test results show that more than 90% reduction for a certain frequency can be achieved for stable pressure statuses. And more than 50% reduction is achieved for varying frequency with step changes. As for the load-varying status, the reduction of 82.7% and 65.8% are obtained before and after pressure change. The method proposed is validated to be effective with both numerical and experimental tests.

FPGA-based interference elimination for health monitoring in dynamic environments

Since flexible wearable sensing devices are mostly used to acquire the human health information by fitting, the vibration generated by the wearer’s movement, physiological state, environment, and other dynamic factors will interfere the accuracy of collected signals. In order to solve the signal interference problem in dynamic environments, a system is needed to eliminate the strong interfering signals in disturbing scenarios in order to acquire the target signal. In this paper, a FPGA-based system is designed to eliminate the signal interference, where a PFGA chipset is served as the core hardware part, an adaptive notch filter is used to process the sensing signals and the FPGA and the host computer are interacted in real time, thus various vibration noises suffered by the flexible sensing device could be eliminated when it is applied to health monitoring in dynamic environments.

Study on the Mechanism and Suppression of Harmonic Vibration of AMB-Rotor System

The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

Improving the Control Strategy of the DVR Compensator Based on an Adaptive Notch Filter with an Optimized PD Controller Using the IGWO Algorithm

One of the objectives of electrical distribution networks is to provide customers with access to high‐quality electricity. Because any disruptions in these systems result in voltage disorders, different devices are employed to offset these disruptions on consumers who are more susceptible. One of the most important and contemporary pieces of equipment that is connected in series with the network is dynamic voltage restoration (DVR), which shields delicate loads from network voltage issues by injecting the proper voltage. This article presents a DVR control scheme optimized with improved grey wolf optimization (IGWO) that uses a proportional derivative (PD) controller and adaptive notch filter (ANF). The output LC filter’s resistance has been removed, and the control system has actively engaged in oscillation damping in order to accelerate dynamic responsiveness and lower system losses. The major component of the voltage, which comprises its frequency, amplitude, and phase, is extracted using ANF. The capacitor current of the output filter in this structure is fed back to the control system and from the current mode control in the inner loop to boost stability. Owing to the occasionally complex dynamic behavior in distribution networks, particularly during a fault, the system’s frequency response has been altered and response speed has been accelerated using the PD controller. This kind of controller is distinguished by its accurate functioning in the presence of frequency deviations and its swifter dynamic reaction in the face of voltage swell and sag. In order to improve the THD and voltage sag indicators of the sensitive load, the PD coefficients were adjusted using the IGWO algorithm. As a consequence, the simulation results demonstrated that the suggested controller performed better than traditional controllers.

Harmonic vibration suppression in active magnetic bearing systems with adaptive notch filter and repetitive control

Harmonic vibration suppression in active magnetic bearing systems with adaptive notch filter and repetitive control

Adaptive Notch Filters for Bus Voltage Control and Capacitance Degradation Prognostic of Single-Phase Grid-Connected Inverter

Two adaptive notch filters (ANFs) based on the double integrators (ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> ) and the unbalanced synchronous reference frame control (ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</sub> ) were applied to the bus voltage control of a single-phase grid-connected inverter. This paper also proposes a non-invasive prognostic function for the degradation of the bus capacitance using the difference between the bus ripple amplitudes estimated from the ANFs and the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axes currents with the nominal bus capacitance. The ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> , ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</sub> , and conventional notch filters were experimentally validated with a 220-V, 50-Hz, 2.5-kW two-stage inverter. The bus voltage control schemes using the three notch filters tuned at a fast bandwidth of 30 Hz exhibited identical performance with the grid current harmonics complied with the IEEE 1547 standard. Moreover, the ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> and ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</sub> control schemes maintain low current distortion with a variable grid frequency of 45-55 Hz. The capacitance degradation prognostic function accurately responded to a 27% reduction in the bus capacitance. Considering the control performance and computational effort, the ANF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> is suitable for bus voltage control of the single-phase inverter.

An Efficient Narrowband FxLMS Algorithm for A 3-Axis Active Mount

The Active Mount (AM) controls the vibrations caused by the movement of a mechanical system resting on top of it. Vibration caused by mechanical systems often consists of several dominant frequency components. Therefore, we need an adaptive algorithm controlling tonal vibration components effectively. The FxLMS algorithm widely used for active vibration control raises several issues as the tone number and control channel increase. This paper proposes an efficient narrowband FxLMS algorithm for controlling multiple tonal vibrations occurring in a 3-axis AM. To this end, the secondary path's magnitude and phase responses are modeled tone-by-tone, independently using two-tap filters. Narrowband control filters are constructed for each tone using a narrowband signal model. In addition, a reference sensor is mounted on top of AM, from which tonal references are estimated using adaptive notch filters (ANFs). The proposed algorithm was simulated using transfer functions obtained in a 3-axis AM. Results show that the proposed algorithm effectively controls multiple tonal components by minimizing total errors measured along the 3-axis.

Alleviation of Power Quality Issues in MVF-DEANF-PLL Based Solar PV Systems under Polluted Grid Conditions

Solar energy is a sustainable and environmentally safe power source due to its widespread availability and cleanliness. Nowadays, the grid-integrated solar photovoltaic system (SPVS) has to work with a polluted grid, an imbalanced load, and changing solar irradiation. When the grid is polluted, it is also crucial to enhance power quality (PQ) at a common coupling point (CCP) while supplying significantly distorted and unreliable loads. For effective synchronization and the production of unit templates, it is necessary to retrieve positive sequence components (PSCs) from distorted/imbalanced grid voltages. In this study, a control algorithm for a grid-integrated SPVS is developed using a multi-variable filter dual-enhanced adaptive notch filter phase-locked loop (MVF-DEANF-PLL) which offers seamless grid synchronization and PQ issue alleviation. In a polluted grid environment, the proposed control approach aids in the reduction in current/voltage harmonics, DC offset, unity power factor (UPF) operation, and rapid estimation of sequence components. Even in unbalanced grid conditions, the proposed control approach efficiently extracts PSCs of both unbalanced load current and polluted CCP grid voltages. These PSCs are utilized to generate unit templates and reference source currents. By using a flexible step-size incremental conductance (FSSINC) maximum power point tracking (MPPT) technique, the highest available power of SPVS is gathered. MATLAB/Simulink is utilized for modelling a 7.22 kW SPV system, and results from simulations which depict that the proposed algorithm efficiently resolves PQ concerns in distribution networks with a polluted grid. Test observations of a 1 kW laboratory-developed SPVS prototype were recorded in compliance with the IEEE-519 standard. The suggested control technique complies with the aforementioned standards by providing a sinusoidal balanced source current that has a THD of 2.5%. Comparisons between the proposed control’s performance and that of a conventional SRF-PLL-based control technique were also performed.

High-Frequency Harmonic Suppression Strategy and Modified Notch Filter-Based Active Damping for Low-Inductance HPMSM

The voltage inverters have the high-frequency switching characteristic, which will generate massive high-frequency harmonics in the motors. Especially, the inductance of the high-speed permanent magnet synchronous motor (HPMSM) is designed to be small, and the high-frequency harmonic content will be higher than that of ordinary motors, which adversely affects the system. To overcome this problem, this paper proposed a harmonic suppression method based on the LC filter and the adaptive notch filter for HPMSMs. The LC filter is connected between the inverter and the HPMSM to filter out high-frequency harmonics, however, at the cost of the system resonance. Therefore, the adaptive notch filter with the frequency tracking capability is designed to offset specific resonant peaks by constructing an antiresonant peak. The least mean square adaptive algorithm automatically adjusts the filter parameters according to the variation of the input signal to ensure accurate filtering in complex cases. Simulation and experiment results prove the practicability and effectiveness of the proposed scheme. The harmonic contents of HPMSM are significantly reduced, and the dynamic response performance of the control system is improved.

Instantaneous multi-frequency tracker for nonstationary vibration signal in mechanical system

A novel instantaneous frequency (IF) tracking method for non-stationary measured signals with single-frequency, multi-frequency, and harmonic-frequency is presented in this paper. Firstly, the deficiency of the mainstream time-domain IF tracking methods, such as adaptive notch filter (ANF) and Extended Kalman Filter (EKF), etc., are analyzed. Then the relationship of the amplitude, frequency, and signal value of a periodic signal in adjacent time intervals is derived, the influence of amplitude change on IF tracking results is verified, and a new state-space model for the IF tracking of a non-stationary measured signal is constructed by using the adjacent non-stationary measured signal, signal amplitude, and frequency, and the EKF is used to update the state of the model. After that, a series of non-stationary signals whose amplitude, frequency, and phase change linearly, nonlinearly, and mutation over time are designed to verify the IF tracking performance of the proposed algorithm. From the simulation results and 1000 times Monte Carlo simulation results, the proposed algorithm has faster convergence speed, higher convergence accuracy, and better robustness, compared with mainstream time-domain frequency tracking algorithms, such as ANF and EKF. Based on the proposed single-frequency IF tracking model, a multi-frequency signal IF tracking model is constructed to track the IF of non-stationary measured signals containing multiple frequency components. The effectiveness of the proposed multi-frequency IF tracking algorithm for multi-frequency signal and harmonic signal IF tracking is verified by simulation cases. After that, some experimental cases are given to further verify the feasibility of the proposed IF tracking algorithm. From the experimental results, the effectiveness of the proposed algorithm is compared with other time-domain algorithms. In addition, the initial value of frequency is set to zero in all the processes of simulation and experiment, which effectively avoids the influence of the initial condition of frequency on the IF tracking result.

Stability control of high-speed magnetic levitation turbomolecular pumps with shock-excited disturbance

The disturbance suppression of magnetic levitation turbomolecular pumps is a critical problem in industrial applications. This work addresses the stability control of high-speed magnetic levitation turbomolecular pumps with shock-excited disturbance. A disturbance suppression method based on improved linear extended state observer is proposed to attenuate the impact of external low-frequency disturbing force on a magnetic levitation turbomolecular pump. Firstly, a linear extended state observer of an active magnetic bearing is obtained by analyzing the rotor dynamics model. Then, the detailed descriptions of external disturbance suppression method using linear extended state observers and adaptive notch filters are discussed for the system. The boundary condition of the parameters of the improved linear extended state observer is determined. The root loci of the closed-loop system with improved linear extended state observers is also investigated. Finally, simulation and experimental results on a magnetic levitation turbomolecular pump show the applicability of the proposed method. The results show that the proposed method can attenuate the rotor vibration displacement caused by impact by 46.9%.

Analysis and Elimination of Speed Measurement Ripple in Sinusoidal Coded Gearwheel Encoder for Spindle Motor Drive

The gearwheel encoder with a magnetoresistive (MR) sensor is robust, simple, and widely used in high-speed industrial motor drives. Moreover, a high-precision rotor position detection is possible with the gearwheel encoder due to its large number of output pulses per revolution. The MR sensor outputs two sinusoidal signals that are 90 degrees apart, the period of which matches with one tooth of the gearwheel. However, these output signals are not perfectly sinusoidal because the MR sensor is manually mounted, and the magnitudes of these signals depend on the distance between the MR material and gearwheel. This slight imperfection in the output signals provokes large speed ripples in the speed measurement. This study analyzed the speed measurement ripples, and an effective ripple-elimination method was devised based on the results of the analysis. Ripple components caused by each signal error were calculated from the error signal models, and exact ripple frequencies were extracted. From the calculation results, a frequency adaptive series notch filter algorithm was designed. The simulation and experimental results demonstrated the effectiveness of the analysis and proposed approach. It is obviously shown through the experimental results that the speed measurement ripple is almost eliminated with the proposed method, and, thus, the analysis is valid.

Off-Board Bidirectional Electric Vehicle Charger Featuring Reactive Power Compensation and Reduced Total Harmonic Distortion for Enhanced Efficiency and Power Quality

The purpose of this study is to explain a recently developed off-board battery charger system for electric vehicles (EVs) that is capable of supporting grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations, in addition to adjusting for reactive power. A utility-connected AC-DC cascaded H-bridge (CHB) converter is included into the system design. This converter is responsible for controlling the power exchange that occurs between the grid and the battery while a bidirectional DC-DC converter is located at the rear end of the system. There is galvanic separation between the grid and the user end of the charger, which is included for the purpose of increasing safety. In order to manage electric vehicle power and battery current, the suggested system makes use of an ANFIS controller. This controller adheres to active power orders for both G2V and V2G modes, and it also provides reactive power adjustment when it is necessary. Furthermore, a control algorithm that is based on an adaptive notch filter has been developed in order to estimate network phases and achieve accurate current synchronization without the need for phase-locked loops (PLLs). This has resulted in the simplification of controller design and an improvement in both the steady-state and dynamic performance of the system. The efficiency of the suggested system in regulating reactive power in V2G and G2V scenarios is shown by the experimental results that were achieved in a MATLAB environment.

Periodic Traction Force Fluctuations Suppression Strategy of Maglev Train Based on Flux Linkage Observation and Harmonic Current Injection

To suppress the periodic traction force fluctuations of maglev train caused by the current harmonics and the excitation flux linkage harmonics of long stator linear synchronous motor (LSLSM), a strategy based on flux linkage observation and harmonic current injection is proposed in this paper. First, the mathematical models of the LSLSM in single feed (SF) and double feed (DF) modes are established and simplified. Then, considering the characteristics of variable frequency and phase lag of the LSLSM, an improved discrete resonant controller (RSC) with pole correction and whole frequency domain phase compensation is designed to suppress the traction force fluctuation caused by current harmonics. To suppress the traction force fluctuations caused by the flux linkage harmonics, a sliding mode flux linkage observer (SMFO) is designed and combined with an adaptive notch filter (ANF) to estimate specific flux linkage harmonics in real-time. By analyzing the flux linkage component in the traction force equation, appropriate harmonic currents are injected and tracked by the RSC. Hardware-in-the-loop (HIL) experiments verify the effectiveness of the proposed strategy.

Suppression of Gyroscopic Torque Disturbance in High Speed Magnetically Levitated Rigid Rotor Systems Based on Extended State Observer

The gyroscopic torque disturbances generated by base motion directly affects the stability of the high speed magnetically levitated centrifugal compressor (MLCC). This article explores a disturbance suppression method for the high-speed magnetically levitated rotor (MLR) system based on improved linear extended state observer (LESO). Firstly, the model of the high-speed MLR system with base motion is established, and the characteristics of the gyroscopic torque disturbance are analyzed. Then, a LESO with adaptive notch filter is designed for disturbance estimation and compensation of the magnetic bearing, and its convergence performance and disturbance tracking speed are deduced. Furthermore, due to the gain attenuation introduced by LESO, an innovative gain compensator is utilized to improve controller dynamic performance. Finally, simulation and experimental results demonstrate that the proposed method can effectively reject the gyroscopic torque disturbances in high speed MLCC.