Adaptive Notch Filter Algorithm Research Articles

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.

Automatic sleeping time estimation and mild traumatic brain injury (mTBI) detection using actigraphy data

Sleep schedule and circadian phase irregularity are associated with some health problems and diseases, e.g., narcolepsy, circadian disorder, and concussion. Actigraphy has been widely used in the study of sleep and circadian rhythms. This paper presents a method for estimating the sleep/wake state based on the minute-by-minute actigraphy data measured by wrist actigraphy and its associated scoring software. The circadian phase shift is estimated from actigraphy data using an adaptive notch filter algorithm. Compared with the scoring methods used in wrist actigraphy, the estimated wake-onset time from our method is more consistent with the sleep logs reported by the subjects. Concussion detection based on the sleep-related features calculated from actigraphy data is also presented, with detection accuracy up to about 90%. This result implies that the concussion is closely related to sleep and circadian disruption.

Adaptive notch filter under indirect and direct current controls for active power filter

This study presents the implementation of adaptive notch filter (ANF) as reference signal extraction for shunt active power filter (APF) in indirect current control (ICC) and direct current control (DCC) modes for three phase system. The ANF functions to filter the signal that inputted to it by producing a fundamental signal and harmonics signal. The advantage of applying the ANF algorithm is based on its simple design that giving the ANF advantages to be utilize in microcontroller. The performance of the ANF is validated though MATLAB simulation in ICC dan DCC configurations. Based on the simulation results, the ANF is capable to work efficiently for both ICC and DCC modes, but in term of efficiency, the ICC mode is clearly showing a better harmonics mitigation result. Base on the result also it shown that the ANF is capable of mitigate the harmonics below the standard required by the IEEE 519-92. The application of ANF is useful to be applied due to its simple design and filtering method.

Suppression of Synchronous Current Using Double Input Improved Adaptive Notch Filter Algorithm

In order to suppress the influence of the synchronous vibration generated by the unbalance of magnetically suspended control moment gyro on the attitude control accuracy and stability of the satellite platform, this article first introduces the working principle of the magnetically suspended high-speed rotor system, and also establishes the dynamic model of the magnetically suspended rotor with unbalance mass. At the same time, the main sources of unbalance vibration are also analyzed. Finally, an improved adaptive notch filter based on double input is designed. The filter takes the rotor radial X, Y two-channel displacement sensor signals as inputs, and uses the characteristics orthogonal to each other to simultaneously enter the system. The rotor can be automatically balanced by adjusting the convergence factor and the compensation angle to adaptively suppress the synchronous current in a widely operating speed range. Simulation and experimental results show that the method can effectively eliminate the synchronous current in a widely operating speed range and improve the stability of the system. This research on the microvibration of the rotor is of great significance and application value.

A narrowband active noise control system with a frequency estimator based on Bayesian inference

Narrowband active noise control (NANC) achieves good performance in controlling low-frequency periodic noise. Such control is necessary to obtain the frequency information of the primary periodic noise, including the number of frequency components and the individual frequency values, to generate reference signals. The performance of the NANC system mainly depends on the accuracy of frequency estimation of the primary periodic noise. In this article, a frequency estimator based on Bayesian inference that can obtain accurate frequencies as well as the number of frequency components is applied to a NANC system. Numerous computer simulations are conducted. Simulation results show that the proposed system outperforms a conventional NANC system with the adaptive notch filter (ANF) algorithm at low signal-to-noise-ratio (SNR) primary periodic noise.

The Grid Voltage’s Asymmetrical Fault Detection Method based on Variable-Step LMS Adaptive Notch Filter Algorithm

For wind turbine systems (WTS), the grid voltage fault detection algorithm determines the response speed of WTS to grid voltage fault. This paper proposed a sort of voltage asymmetrical fault detection method, to detect negative-sequence component in grid voltage, variable-step (VS) least mean square (LMS) adaptive notch filter (ANF) is applied to eliminate the 2nd-harmonic frequency component. The application of ANF can separate negative-sequence component from grid voltage, therefore the voltage asymmetrical fault can be detected; the self-tuning of controllable parameters of ANF can be realized by the LMS adaptive algorithm, which is convenient and efficient in practical application; furthermore, because the variable step size adjustment is adopted, the contradiction between convergence rate and steady-state error of ANF can be solved. The MATLAB/Simulink simulation and FFT analysis results are in conformity with the theorical analysis, which proves the feasibility of the method.

A narrowband active noise control system with a frequency estimation algorithm based on parallel adaptive notch filter

Abstract Active noise control (ANC) instead of traditional passive method shows good low-frequency performance especially for periodic noise signals. To obtain accurate reference signal and remove the secondary feedback effect, frequency estimation algorithms are often used in narrowband ANC systems. In this work, a parallel adaptive notch filter (parallel ANF, PANF) algorithm is proposed to obtain accurate estimation of frequency which is used for generating reference signal in a sinusoidal form. In the proposed PANF algorithm, multiple tones are separated in the feedback reconstruction process to reduce the frequency-interfering effect. As a result, the estimation of multiple frequencies has high accuracy as well as the triangular cascaded ANF (TCANF) algorithm and the computation burden is greatly reduced to the level of the linear cascaded ANF (LCANF) algorithm. Detailed performance analysis is conducted to acquire the deviation of frequency estimation algorithm and the mean square error (MSE) of the ANC system. Finally, extensive simulations and narrowband ANC experiments are carried out in a pipe system to verify theoretical results.

Variable step‐size oscillator‐based adaptive notch filer algorithm using maximum correntropy criterion

A novel oscillator-based adaptive notch filter (OSC-ANF) algorithm is presented. The proposed algorithm has robustness against the impulsive noise because it is derived by using the maximum correntropy criterion (MCC). In addition, the variable step-size MCC-OSC-ANF algorithm is proposed to improve the frequency estimation performance. Experimental results show that the proposed algorithms perform better than the previous algorithm under impulsive noises.

Analysis of frequency estimation MSE for all-pass-based adaptive IIR notch filters with normalized lattice structure

This paper theoretically analyzes the Mean Square Error (MSE) on the steady-state frequency estimation realized by the all-pass-based adaptive notch filtering algorithms with the normalized lattice structure. The adaptive algorithms to be considered are the Simplified Lattice Algorithm (SLA) proposed by Regalia and the Affine Combination Lattice Algorithm (ACLA) proposed by the authors. For these two algorithms, we derive the frequency estimation MSE in closed-form. The derivation is based on construction of a linear time-invariant model for generation of frequency estimation error, and division of this model into two submodels of which output signals are statistically uncorrelated to each other. This strategy leads to more accurate theoretical MSE expressions than the direct use of the existing analysis methods. Simulation results demonstrate that our theoretical MSE expressions are in very good agreement with the simulated MSE values.

From adaptive control to variable structure systems – seeking harmony

From adaptive control to variable structure systems – seeking harmony

Multi‐input adaptive notch filter and observer for circadian phase estimation

SummaryAccurate estimation of circadian phase is critical to the assessment and treatment of circadian disruption. Direct measurements of circadian rhythm markers such as dim light melatonin onset and core body temperature are inconvenient and acquired at best at low rate. On the other hand, measurements of other circadian rhythm‐modulated signals such as actigraphy, heart rate, and body temperature are convenient but are typically masked by many other factors.In this paper, we present a new multi‐input adaptive notch filter algorithm that can be used to extract the periodic components from multiple circadian signals simultaneously. We also prove some stability properties of the proposed filter. Once the periodic components are extracted, the next step is to relate their phases with the circadian phase. For this, we propose a nonlinear observer, which is based on a model of the circadian phase dynamics. The model takes the form of a first‐order ODE, incorporating the concept of phase response curve, which is widely used in the study of biological oscillators. We also prove the stability of the observer. We evaluate our algorithms using simulation data generated from a circadian rhythm model for fruit flies (Drosophila melanogaster). Copyright © 2016 John Wiley & Sons, Ltd.

Unity power factor operation and neutral current compensation of diesel generator set feeding three‐phase four‐wire loads

This study deals with power quality improvement in a diesel generator (DG) set-based standalone supply system feeding three-phase four-wire(3P4W) loads. The proposed system consists of a diesel engine, three-phase wound field synchronous generator, a four-leg voltage source converter (VSC) and3P4W loads. The four-leg VSC with a capacitor connected on its DC link is used for neutral current compensation and unity power factor operation of the DG set. In addition, the VSC provides harmonics elimination and the load balancing. The voltage of the DG system is controlled by excitation control of the synchronous generator and the frequency is controlled by speed regulating system of the diesel engine. The speed of the engine is regulated by controlling the fuel injection of the diesel engine. An adaptive theory-based notch filter algorithm is used to extract fundamental component of the load currents for estimation of reference source currents.

Adaptive Tunable Notch Filter for ECG Signal Enhancement

In this paper, a high performance adaptive tunable notch filter algorithm for accurate estimation of ECG signal is proposed. The power line interference and muscle contraction noise is significantly suppressed using the proposed adaptive notch FIR filter with tunable notch frequency. An important aspect of the proposed filter scheme is that it preserves the selectivity and attenuation at the notch frequency. The filter is optimized and its coefficients are computed such that the noise in ECG signal is minimised in a specified frequency range. The proposed algorithm estimates the frequency of unwanted signal and updates accordingly the filter coefficients for optimum performance. Based on simulation results, it is demonstrated that the proposed technique can be used to accurately extract the ECG information such as heart beat rate from noisy ECG signal and significant improvement in output signal-to-noise ratio (SNR) can be achieved as compared to the normal adaptive notch filter technique.

Arctangent based adaptive algorithm for a complex IIR notch filter for frequency estimation and tracking

An arctangent (AT) based adaptive algorithm for a first-order complex adaptive IIR notch filter (CANF) is proposed in this paper. The objective of this work is to overcome some drawbacks including slow convergence speed and high sensitivity to impulsive noise of the previous gradient and nongradient based adaptive algorithms. The proposed AT algorithm employs the ratio of output to regressor signal as an error criterion where the arctangent value of such a ratio is employed to adjust the filter parameter. It is found that the proposed algorithm provides not only high speed convergence but also high impulsive noise robustness. Moreover, very low bias of the frequency estimate is also obtained. In addition, difference equation for the convergence in the mean and coarse stability bound in mean sense are derived. Computer simulations are conducted to show the performance of the proposed AT algorithm.

Mean square error analysis of unbiased modified plain gradient algorithm for second-order adaptive IIR notch filter

In this paper, theoretical analysis for deriving the estimation of mean square error (MSE) at steady-state of an adaptive IIR notch filter using unbiased modified plain gradient (UMPG) algorithm is presented in closed form. Moreover, the stability bound of the algorithm is also derived. To confirm the analytical results, the computer simulations are conducted to corroborate the effectiveness of the UMPG algorithm. Furthermore, the performances of the algorithm are also compared with the modified plain gradient (MPG) algorithm, unbiased plain gradient (UPG) algorithm and simplified lattice algorithm (SLA).

Sky-Hook with Adaptive Disturbance Cancellation Control for Flexible Structures by Active Vibration Control Unit

This study presents Active Wheel Damper (AWD) unit which can be fixed on the flexible structures such as cantilever beam with ease. The AWD uses a gyro sensor to measure the absolute angular velocity due to the vibration of deflection of the structure directly, and can construct sky-hook control with no difficulty by direct feedback of the angular velocity. In this study, Sky-hook With Adaptive Disturbance Cancellation (SWADC) control, which is constructed as a combined control system of sky-hook control and adaptive disturbance cancellation control, is also proposed to enhance the performance of vibration suppression of AWD unit. Adaptive algorithm, which can estimate the frequency of the vibration of the structure in real-time, is derived based on adaptive notch filter algorithm, and estimated frequency is used for the model of disturbance observer which estimates harmonic disturbance. Performance of vibration suppression of the AWD is shown by simulation and experiment in this study.

Sky-Hook with Adaptive Disturbance Cancellation Control for Flexible Structures with an Active Vibration Control Unit

This study presents an Active Wheel Damper (AWD) unit that can be easily mounted on flexible structures such as cantilever beams. The AWD uses a gyro sensor to directly measure the absolute angular velocity, which is the rotational velocity of the slope angle of a deflection curve caused by the flexible vibration of the structure, and can be used to realize a skyhook control by the direct feedback of the angular velocity. This study proposes a Sky-hook With Adaptive Disturbance Cancellation (SWADC) control—which is constructed as a combined skyhook control and an adaptive disturbance cancellation control system—to enhance the capability of the AWD unit to suppress vibrations. An adaptive algorithm, which estimates the frequency of vibration of a structure in real time, is derived on the basis of an adaptive notch filter algorithm. The estimated frequency is used to model a disturbance observer that estimates harmonic disturbances. This study demonstrates the vibration-suppression performance of the AWD unit by numerical simulations and experiments.

Unbiased plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros

This article proposes an unbiased plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros. The proposed algorithm employs removing a dominant parameter that produces inherent bias. By using this technique, the performances are improved with slight expense in computational complexity. In this paper, theoretical analysis for deriving the estimations of bias and mean square error (MSE) at steady state are presented in closed form. Moreover, the stability bound of the algorithm is also derived. To confirm the analytical results, the computer simulations are provided to corroborate the effectiveness of the proposed algorithm. Furthermore, the performances of the algorithm are also compared with the plain gradient (PG) and modified plain gradient (MPG) algorithms.

Direct frequency estimation based adaptive algorithm for a second-order adaptive FIR notch filter

This work deals with the problem of the frequency estimation of a sinusoidal signal corrupted by broad-band noise. The direct frequency estimation based adaptive algorithm for a second-order adaptive finite impulse response (FIR) notch filter (AFNF) is thus proposed. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimated parameter. The performances including the rate of convergence and the mean square error (MSE) can be easily controlled by using only one parameter, i.e., step size parameter. Moreover, the proposed filter is simple to implement and suitable for real-time applications. In addition, the difference equations for the convergence in the mean and mean square, and the closed form expressions for the steady-state estimation bias and MSE are also carried out. Finally, the simulation results are provided to confirm the theoretical analysis.

Attitude control of a flexible launch vehicle using an adaptive notch filter: Ground experiment

Attitude control of a flexible launch vehicle using adaptive notch filtering with real-time control is addressed in this paper. An experimental ground model is developed to verify the stability of the adaptive control technique based upon an adaptive notch filter. The experimental setup simulates the planar motion of a flexible launch vehicle as a coupled dynamics of rigid-body pitch motion and flexible vibration. The adaptive notch filter, which updates the filter parameters continuously from a sensor measurement, is implemented in real-time. The principal purpose of this study is to apply the adaptive notch filter algorithm in a feasibility study to assess its practical implementation. Through this experimental study, it was found that an adaptive controller in the form of an adaptive notch filter successfully stabilizes the uncertain and time-varying launch vehicle model dynamics via a thrust vector control.