Compensation Filter Research Articles

Time-space Fourier κω′ filter for motion artifacts compensation during transcranial fluorescence brain imaging

Intravital imaging of brain vasculature through the intact cranium in vivo is based on the evolution of the fluorescence intensity and provides an ability to characterize various physiological processes in the natural context of cellular resolution. The involuntary motions of the examined subjects often limit in vivo non-invasive functional optical imaging. Conventional imaging diagnostic modalities encounter serious difficulties in correction of artificial motions, associated with fast high dynamics of the intensity values in the collected image sequences, when a common reference cannot be provided. In the current report, we introduce an alternative solution based on a time-space Fourier transform method so-called K-Omega. We demonstrate that the proposed approach is effective for image stabilization of fast dynamic image sequences and can be used autonomously without supervision and assignation of a reference image.

Gaussian Recursive Filter for Nonlinear Systems with Finite-step Correlated Noises and Packet Dropout Compensations

Abstract This paper is focused on the nonlinear state estimation problem with finite-step correlated noises and packet loss. Firstly, by using the projection theorem repeatedly, the mean and covariance of process noise and measurement noise in the condition of measurements before the current epoch are calculated. Then, based on the Gaussian approximation recursive filter (GASF) and the prediction compensation mechanism, one-step predictor and filter with packet dropouts are derived, respectively. Based on these, a nonlinear Gaussian recursive filter is proposed. Subsequently, the numerical implementation is derived based on the cubature Kalman filter (CKF), which is suitable for general nonlinear system and with higher accuracy compared to the algorithm expanded from linear system to nonlinear system through Taylor series expansion. Finally, the strong nonlinearity model is used to show the superiority of the proposed algorithm.

Prescribed Performance Adaptive Backstepping Control for Winding Segmented Permanent Magnet Linear Synchronous Motor

In this paper, a prescribed performance adaptive backstepping control (PPABC) strategy is proposed to control the speed of a winding segmented permanent magnet linear synchronous motor (WS-PMLSM) with variable parameters and an unknown load disturbance. Firstly, a mathematical model of WS-PMLSM is provided. Then, the prescribed performance technique is introduced in the adaptive backstepping control to improve the transient performance and ensures the tracking error converges within a predetermined range. In addition, a constrained command filter is introduced to address the problem of differential expansion which exists in the traditional backstepping method, and a filter compensation signal is designed against the filter error. Moreover, the adaptive law is designed based on Lyapunov stability theory to estimate the uncertainties caused by parameter changes and load disturbances. The stability of the proposed control strategy is given and the simulation of the control system is carried out under the proposed PPABC in contrast with another backstepping control and traditional PI control. Finally, the experiment is conducted to further show the effectiveness of the proposed controller.

Positioning Accuracy of the Shearer Based on a Strapdown Inertial Navigation System in Underground Coal Mining

Automation and intelligent coal mining comprise the most important fields in coal mining technology research. The key to automation and intelligent coal mining is the automated mining of the working face, and accurate positioning of the shearer is one of the most important technologies in the automated mining process. However, significant defects in non-inertial navigation system (INS)-based methods have led to low positioning accuracy. In this paper, we propose a new shearer positioning technology to further improve the positioning accuracy of the shearer and monitor the shearer position in real time. The shearer positioning system proposed is based on the strapdown inertial navigation system (SINS). We conducted shearer positioning experiments with gyroscopes, accelerometers, and other inertial navigation instruments. The experimental results are thoroughly studied on the basis of error compensation techniques such as inertial instrument zero bias compensation and Kalman filter compensation. Compared with traditional shearer positioning technology, the experimental results show that the shearer positioning system based on SINS can achieve more accurate positioning of the shearer and can accurately reflect the running characteristics of the shearer working the mining face.

Analisis Pengaruh Static Synchronous Series Compensator Terhadap Kestabilan Transien Menggunakan Metode Nyquist (Analysis of the Static Synchronous Series Compensator’s Effect on Transient Stability Using the Nyquist Method)

Loss of synchronization causes a generator not in steady state condition, causing system instability. In this paper, Nyquist method is used to determine the transient stability of a synchronous generator using the Nyquist curve. The system is unstable if the G(jω) curve is further away from the point -1 + j0, while the gain margin value is below 6 dB and the phase margin has a value below 30°. The response of the system shows that the rotor angle oscillation on the generator is not synchronous, while the power angle experiences irregular transients so that the power angle increases until it cannot return to its steady state position. By using the Static Series Synchronous Compensator (SSSC) filter, the rotor angle oscillation response after 0.1 seconds begins to stabilize at an angle of 50°. The effect of the SSSC filter also affects the bus voltage oscillations from 0.15 seconds to 0.05 seconds and the real power oscillations from 0.13 seconds to 0.06 seconds.

Fully Integrated Dual-Mode X-Band Radar Transceiver Using Configurable Receiver and Local Oscillator

In this paper, a fully-integrated dual-mode X-band radar transceiver that supports Doppler radar and frequency modulated continuous wave (FMCW) radar is proposed. To remove large off-chip DC-blocking capacitors in the Doppler mode, the double-conversion technique and local oscillator (LO) chopping technique are introduced. These techniques remove the DC offset and makes the transceiver more robust to the TX to RX leakage. In addition, they also improve the noise figure (NF) by filtering out 1/f noise of the analog baseband. The FMCW radar is realized using a direct-conversion receiver and a chirp generator. The chirp generator consists of a frequency sweep generator (FSG) and a fractional-N phase-locked loop (PLL). All the analog baseband components including a programable gain amplifiers (PGA) and 1/R 4 range compensation filters are integrated on the chip as well as a bandgap and low-dropout regulators. The operating frequency is from 9.7 to 12.3 GHz, which consumes 216 mW in Doppler mode and 201.6 mW in FMCW mode from a 1.2-V supply voltage. The maximum chirp bandwidth is 750 MHz and the maximum receiver gain is 76 dB with 6-dB gain step. The chip size of the transceiver is 7.68 mm 2 including all the pads.

H-Infinity Control of an Adaptive Hybrid Active Power Filter for Power Quality Compensation

This article highlights an optimal robust control technique called H-infinity, which thanks to a particular algorithm offers several solutions in the experimental implementation of harmonic compensators of systems with API-siemens modules. This control and command technique is directly tested on a TLC adaptive hybrid filter topology that provides benefits, such as reduced switching losses when injecting currents in the network, limitation of resonance problems and above all low power consumption at the DC bus level, thus allowing us to obtain results for 105 V to be compared with existing models in the literature which require 600 V for the same performance. This article therefore simultaneously offers two essential contributions to the optimization of harmonic pollution control. A first contribution is essentially based on the H-infinite algorithm and its particularity in its implementation on our TLC hybrid model. The second is on the advantages offered by the TLC-HAPF hybrid topology. The results obtained with this algorithm give us THDs conforming to the IEEE 519-1996 and which are very meaningful compared to the results obtained with other robust and stochastic control algorithms taken under the same conditions.

Construction and Performance Investigation of Three-Phase Solar PV and Battery Energy Storage System Integrated UPQC

This study examines the use of Unified Power Quality Conditioner (UPQC) to mitigate the power quality problems existed in the grid and the harmonics penetrated by the non-linear loads. The UPQC is supported by the Photovoltaic (PV) and Battery Energy Storage System (BESS) in this work. Generally, the PV system supplies the active power to the load. However, if the PV is unable to supply the power then the BESS activates and provides power especially during the longer-term voltage interruption. The standalone PV-UPQC system is less reliable compared to a hybrid PV-BESS system because of its instability and high environment-dependency. Therefore, BESS will improve the voltage support capability continuously in the longer-term, reduce the complexity of the DC-link voltage regulation algorithm, and keep producing clean energy. The phase synchronization operation of the UPQC controller is directed by a self-tuning filter (STF) integrated with the unit vector generator (UVG) technique. Implementation of STF will make sure the UPQC can successfully operate under unbalanced and distorted grid voltage conditions. Thus, the requirement of a phase-locked loop (PLL) is omitted and the STF-UVG is utilized to produce the synchronization phases for the series and shunt active power filter (APF) compensator in UPQC controller. Finally, the proposed STF-UVG method is compared with the conventional synchronous references frame (SRF-PLL) method based UPQC to show the significance of the proposed technique. Several case studies are further considered to validate the study in MATLAB-Simulink software.

Navigation and Control Scheme for Space Rendezvous and Docking With Maneuvering Noncooperative Target Based on Dynamic Compensation

Rendezvous and docking with noncooperative targets is one of the key technologies for on-orbit service such as satellite maintenance, space supply and space debris cleaning, etc. For the rendezvous and docking with maneuvering noncooperative targets, a relative measurement scheme based on one monocular camera and one distance sensor is designed. A dynamic compensation filter (DCF) is also proposed to estimate the relative state and the unknow maneuver of the noncooperative target. Meanwhile, the control scheme to fulfill the rendezvous and docking mission is given. Compared with the extended Kalman filter (EKF) and variable state dimension estimator (VSDE), the numerical simulation results demonstrate that the proposed estimator has better performance in estimating the relative state and target maneuver. The control scheme based on DCF can accomplish the rendezvous and docking task when the noncooperative target performs time-varying maneuvers.

In-ear microphone measures in the ear canal with bone conduction stimulation: An application for estimating a cross-talk compensation filter

In-ear microphone measures in the ear canal with bone conduction stimulation: An application for estimating a cross-talk compensation filter

An Adaptive D-FACTS for Power Quality Enhancement in an Isolated Microgrid

Technologies of microgrids (MGs) help power grid evolve into one that is more efficient, less polluting, reduced losses, and more flexible to provide energy consumers’ want and need. Because of the nature of various renewable energy sources (RESs) integrated into the MGs such as variability and inability to accurately predict and control, different technical problems are created. Power quality is one of the most important issues to be addressed, especially harmonic distortion and voltage stabilization. Many devices have been proposed to improve these two aspects that may result from loads nonlinearity and sources uncertainty. In this study, an adaptive switched filter compensator (ASFC) with developed proportional-integral-derivative (PID) controller is proposed to improve the overall dynamic performance of the MGs. The PID’s controller gains are optimally tuned via the application of grasshopper’s optimization algorithm (GOA) to act adaptively with self-tuning as the operating conditions may subject to change during MG operation. Different case studies are proposed to reveal the robustness of the presented ASFC on harmonic mitigation, dynamic voltage stabilization, reactive power compensation and power factor improvement considering the features of RESs such as variations of wind speed, solar PV irradiation and temporary fault conditions. A distribution synchronous static compensator (D-STATCOM), as one of the most popular D-FACTS, with optimal tuned PID controller by using the GOA is also proposed. To validate both the proposed ASFC topology and the modified D-STATCOM, comparative studies including what has been published in literature are examined by using MATLAB/Simulink platform. The results advocate the effectiveness, robustness and latency of the proposed devices.

Trust-region optimization of all-pass filter for compensation of ionospheric dispersion effects on wideband GNSS signals

Ionospheric dispersion causes severe distortions and ranging performance degradations of wideband global navigation satellite system (GNSS) signals. To compensate the non-linear and asymmetrical group delay of the dispersive ionosphere, an all-pass filter in the form of cascaded biquad sections was proposed in our previous study. On this basis, this paper develops an optimal delay-equalization all-pass filter by using the trust-region algorithm to construct the desired group delay and improve the fitting accuracy. The simulation results of the AltBOC(15,10) signal performance demonstrate that the proposed design is more accurate for distortion compensation and thus more effective for ranging bias mitigation than the previous approach.

A robust FACTS based fuzzy control scheme for dynamic stabilization of generator station

Abstract The paper presents a Flexible Alternating Current Transmission Systems (FACTS) based dynamic stabilization scheme using a modified series–parallel switched filter compensation (MSPFC). The proposed dynamic scheme is controlled by an Incremental Fuzzy Logic controller (MIFLC) to ensure fast response dynamic voltage stabilization and efficient energy utilization. The MIFLC employs a multi loop dynamic error driven time-descaled regulation to ensure the fast response of the dynamic controller. A second Weighted Modified PID controller with fixed gains is assessed with the proposed MIFLC controller. The modified control schemes are validated under normal and fault operating situations to ensure fast dynamic control, ac power quality, feeder loss reduction, efficient energy utilization and dynamic AC voltage stabilization regulation. The performance of the proposed controllers is assessed using statistical studies and qualitative comparison that prove the high ability of the proposed MIFLC compared with modified PID controller.

Input parameters estimation from time-varying measurements

A measurement is a dynamical process that aims to estimate the true value of a measurand. The measurand is the input that excites a sensor, and, as a consequence, the sensor output is a transient response. The main approach to estimate the input is applying the sensor transient response to another dynamical system. This dynamical system is designed by deconvolution to invert the sensor dynamics and compensate the sensor response. Digital signal processors enable an alternative approach to estimate the unknown input. There exists a data-driven subspace-based signal processing method that estimates a measurand, assuming it is constant during the measurement. To estimate the parameters of a measurand that varies at a constant rate, we extended the data-driven input estimation method to make it adaptive to the affine input. In this paper, we describe the proposed subspace signal processing method for the measurement of an affine measurand and compare its performance to a maximum-likelihood input estimation method and to an existing time-varying compensation filter. The subspace method is recursive and allows real-time implementations since it directly estimates the input without identifying a sensor model. The maximum-likelihood method is model-based and requires very high computational effort. In this form, the maximum-likelihood method cannot be implemented in real-time, however, we used it as a reference to evaluate the subspace method and the time-varying compensation filter results. The effectiveness of the subspace method is validated in a simulation study with a time-varying sensor. The results show that the subspace method estimation has relative errors that are one order of magnitude smaller and converges two times faster than the compensation filter.

Human movement effects on the performance of the RSSI-based trilateration method: adaptive filters for distance compensation

In this paper, an experimental study of human movement effects in indoor wireless networks on the performance of the received signal strength indicator (RSSI)-based trilateration method is presented. The contribution of this work is that how the RSSI fluctuation caused by human movements nearby a target node influences the estimation accuracy of the trilateration method is studied. Additionally, efficient adaptive filters which can observe RSSI variation levels and select appropriate inputs (i.e., distance values converted from RSSI values) are proposed for handling the RSSI variation problem and compensating the position estimation error. Experiments using low-cost 2.4-GHz wireless nodes have been set and tested in a laboratory room. Results demonstrate that, during the human blocking the communication link between the transmitter and the receiver, RSSI data are fluctuated and the trilateration method shows a large estimation error. Here, the localization accuracy significantly depends on the RSSI variation level. The experimental results also indicate that, by applying our proposed solutions, they can automatically provide appropriate inputs for the trilateration method. The estimation error decreases by 43.76% and 46.28% for our test scenarios.

A photovoltaic integrated unified power quality conditioner with a 27-level inverter

Abstract This paper presents a Unified Power Quality Conditioner (UPQC) with a 27- level inverter based on an asymmetric H-bridge topology. Each phase of the inverter is composed of three H-bridges, supplied by three DC sources scaled in the power of three. The output of the multilevel inverter is connected directly to the point of common coupling (PCC) without the need to a transformer or a filter. The calculation of the Shunt Active Power filter (SAPF) compensation current is based on the generalized theory of synchronous frame (d-q theory) while the calculation of a series active filter voltage is based on Instantaneous Reactive Power (p-q theory). The control of the SAPF is achieved by using a closed loop vector control followed by a new multilevel modulation technique. In addition to the capability of harmonic elimination of both current and voltage drawn from the source, the UPQC can produce real and reactive power to feed the loads during prolonged voltage outages or source shortage. The injection of real and reactive power depends on the state of charge (SOC) of batteries, the frequency of the system, real and reactive power of the load, and power factor at the point of PCC. The proposed UPQC strategy is simulated in MATLAB SIMULINK and the results has shown a significant improved in Total Harmonics Distortion (THD) of both the voltage and currents.

Experimental Validation of a Data-Driven Step Input Estimation Method for Dynamic Measurements

Simultaneous fast and accurate measurement is still a challenging and active problem in metrology. A sensor is a dynamic system that produces a transient response. For fast measurements, the unknown input needs to be estimated using the sensor transient response. When a model of the sensor exists, standard compensation filter methods can be used to estimate the input. If a model is not available, either an adaptive filter is used or a sensor model is identified before the input estimation. Recently, a signal processing method was proposed to avoid the identification stage and estimate directly the value of a step input from the sensor response. This data-driven step input estimation method requires only the order of the sensor dynamics and the sensor static gain. To validate the data-driven step input estimation method, in this article, the uncertainty of the input estimate is studied and illustrated on simulation and real-life weighing measurements. It was found that the predicted mean-squared error of the input estimate is close to an approximate Cramer–Rao lower bound for biased estimators.

Multi-Sensor Fusion and Error Compensation of Attitude Measurement System for Shaft Boring Machine.

To ensure that the shaft boring machine (SBM) runs along the pre-designed axis steadily, the role of the attitude measurement system is essential, but its accuracy and reliability cannot be guaranteed. Currently, there is no effective technology to meet the actual requirements, and there is a lack of relevant theoretical research in this field. Through further study of the attitude analysis method and multi-sensor fusion technology, this paper presents a dual coordinate method, which can be used to describe the attitude characteristics of the SBM. Moreover, this paper discusses the relationships between the attitude changes and the values of the angle as well as displacement and analyzes the implementation complexity and computational efficiency of related algorithms in software and hardware. According to the working characteristics of the SBM, the hardware design and the reasonable layout of the attitude measurement system are provided. Based on multi-sensor data, this paper puts forward an improved method combining a complementary filter with an extended Kalman filter (EKF) for attitude estimation and error compensation. The simulation experiments of different working processes verify the steady-state response and dynamic response performance of the method. Experimental results show that the dual coordinate method and the proposed filter are more suitable for attitude estimation of the SBM compared to other methods.

Underactuated AUV Nonlinear Finite-Time Tracking Control Based on Command Filter and Disturbance Observer.

The three-dimensional (3D) path following problem of an underactuated autonomous underwater vehicle with ocean currents disturbances is addressed in this paper. Firstly, the motion equation under the ocean currents disturbance is established, and the dynamic model of 3D tracking error is constructed based on virtual guidance method. Then, a finite-time control scheme based on super-twisting observer and command filtered backstepping technology is proposed. We adopt super-twisting observer based on finite-time theory to observe the ocean currents disturbances for improving the system robust. A command filtered backstepping is proposed to replace the differential process in the conventional backstepping method for avoiding the differential expansion problem. The filter compensation loop is designed to ensure the accuracy of the filtered signal, and the anti-integration saturation link is designed considering the influence of integral saturation. Lyapunov stability theory is used to prove the stability of the underactuated AUV. Simulation studies are conducted to show the effectiveness and robustness of the controller.

A compensation filter method for extracting surface characteristic from an optical point cloud

Optical devices cannot directly obtain the deformation for welding residual stress (WRS) measurement since it is difficult to get the surface characteristic with a high accuracy of measurement. This paper therefore presents a full-field fast method for WRS measurement based on heterodyne multiple frequency phase shift technology. Furthermore, in order to denoise the acquired point cloud, this paper proposes a novel compensation filter method (CFM) to extract accurate surface topography: specifically, to slice the original point cloud into several independent groups, then smooth each group of the point cloud to obtain the compensation value, and finally to fuse the filtered point cloud with the compensation value to extract surface characteristic. As a result, the simulation and the experiment results show that the CFM can reduce the noise by about 80%. It demonstrates that the novel CFM can maintain the features of the point cloud and remove noise efficiently, indicating the high accuracy of the CFM result and the potential to realize fast WRS measurement.