Proposed Compensation Algorithm Research Articles

Adaptive-Linear-Neuron-Based Dead-Time Effects Compensation Scheme for PMSM Drives

This paper presents an adaptive-linear-neuron (ADALINE)-based dead-time compensation method for vector-controlled permanent-magnet synchronous motor drives. The proposed strategy is achieved by suppressing the sixth-order current harmonics in the dq-axes synchronous reference frame. Four ADALINEs are employed in the proposed algorithm. Two ADALINEs are used for estimating the sixth-order harmonic components of dq-axes currents and the other two are used for generating the dq-axes compensation voltages. The voltage compensators are self-tuned by minimizing the estimated current distortion by means of the least mean square algorithm. The proposed compensation algorithm does not require any additional hardware or complicated signal processing algorithms. Experimental results validating the proposed compensation method are also presented.

타원체를 이용한 3축 센서의 실시간 보정 알고리듬 개발

Multi-axis magnetic and accelerometer sensor are widely used in consumer product such as smart phones. The vector output of multi-axis sensors have errors on each axis such as offset error, scale error, non-orthogonality. These errors cause many problems on the performance of the applications. In this paper, we designed the effective inline compensation algorithm for calibrating of 3 axis sensors using ellipsoid for mass production of multi-axis sensors. The outputs with those kinds of errors can be modeled by ellipsoid, and the proposed algorithm makes sequential mappings of the virtual ellipsoid to perfect sphere which is calibrated function of the sensor on three-dimensional space. The proposed calibrating process composed of four main stages and is very straightforward and effective. In addition, another imperfection of the sensor such as the drift from temperature can be easily inserted in each mapping stage. Numerical simulation and experimental results shows great performance of the proposed compensation algorithm.

An investigation on motor-driven power steering-based crosswind disturbance compensation for the reduction of driver steering effort

This paper describes a lateral disturbance compensation algorithm for an application to a motor-driven power steering (MDPS)-based driver assistant system. The lateral disturbance including wind force and lateral load transfer by bank angle reduces the driver's steering refinement and at the same time increases the possibility of an accident. A lateral disturbance compensation algorithm is designed to determine the motor overlay torque of an MDPS system for reducing the manoeuvreing effort of a human driver under lateral disturbance. Motor overlay torque for the compensation of driver's steering torque induced by the lateral disturbance consists of human torque feedback and feedforward torque. Vehicle–driver system dynamics have been investigated using a combined dynamic model which consists of a vehicle dynamic model, driver steering dynamic model and lateral disturbance model. The human torque feedback input has been designed via the investigation of the vehicle–driver system dynamics. Feedforward input torque is calculated to compensate additional tyre self-aligning torque from an estimated lateral disturbance. The proposed compensation algorithm has been implemented on a developed driver model which represents the driver's manoeuvreing characteristics under the lateral disturbance. The developed driver model has been validated with test data via a driving simulator in a crosswind condition. Human-in-the-loop simulations with a full-scale driving simulator on a virtual test track have been conducted to investigate the real-time performance of the proposed lateral disturbance compensation algorithm. It has been shown from simulation studies and human-in-the-loop simulation results that the driver's manoeuvreing effort and a lateral deviation of the vehicle under the lateral disturbance can be significantly reduced via the lateral disturbance compensation algorithm.

Localization of Sound Sources in Underground Parking Lots

We present a localization of sound sources algorithm for underground parking lots and a compensation algorithm for enhancing localization of sound sources based on the least-squares method (LSM). The proposed localization of sound sources system is designed for the underground parking lots in apartments. The sound location algorithm is referred to as [Formula: see text], and the localization algorithm enhanced with the compensation algorithm is referred to as [Formula: see text]. We also present the performance comparison of the proposed algorithms under directions 135°, 180°, 270°, and 337.5°. The proposed compensation algorithm reduces the error of sound sources by 72.4% on average. The [Formula: see text] algorithm can be applied to the localization of sound sources system for underground parking lots as well as to various sound sources based applications due to its low cost.

Dual‐hop amplify‐and‐forward cooperative relaying in the presence of Tx and Rx in‐phase and quadrature‐phase imbalance

In this study, dual-hop channel state information-assisted amplify-and-forward (AF) cooperative systems in the presence of in-phase and quadrature-phase (I/Q) imbalance, which refers to the mismatch between components in the I and Q branches, are investigated. First, the authors analyse the performance of the considered AF cooperative protocol without compensation for the I/Q imbalance as the benchmark. Then, a compensation algorithm for the I/Q imbalance is proposed, which makes use of the received signals at the destination, from the source and the relay nodes, together with their conjugations to detect the transmitted signal. Moreover, the authors study the considered AF cooperative system implemented with the opportunistic relay selection and the proposed compensation mechanism for the I/Q imbalance. The performance of the AF cooperative system under study is evaluated in terms of average symbol error probability, which is derived by considering transmission in a Rayleigh fading environment. Numerical results are provided and show that the proposed compensation algorithm can efficiently mitigate the effect of the I/Q imbalance. On the other hand, it is observed that the AF cooperative system with opportunistic relay selection acquires a performance gain beyond that without relay selection.

모터 제어 정밀도 향상을 위한 정지 마찰력 보상

DC motor is a representative electric motor commonly utilized in various motion control fields. However, DC motor-based motion control systems suffer from degradation of position precision due to nonlinear static friction. In order to enhance control precision, friction model-based compensators have been introduced in previous researches, where friction models are identified and counter inputs are added to control inputs for cancelling out the identified friction forces. In this paper, a static friction compensator is proposed without use of a friction model. The proposed compensation algorithm utilizes internal state manipulation to generate compensation pulses, and related parameters are easily tuned experimentally. The proposed friction compensator is applied to a DC motor-based motion control system, and results are presented in comparison with those without a friction compensator.

Joint Overlapped Block Motion Compensation Using Eight-Neighbor Block Motion Vectors for Frame Rate Up-Conversion

The traditional block-based motion compensation methods in frame rate up-conversion (FRUC) only use a single uniquely motion vector field. However, there will always be some mistakes in the motion vector field whether the advanced motion estimation (ME) and motion vector analysis (MA) algorithms are performed or not. Once the motion vector field has many mistakes, the quality of the interpolated frame is severely affected. In order to solve the problem, this paper proposes a novel joint overlapped block motion compensation method (8J-OBMC) which adopts motion vectors of the interpolated block and its 8-neighbor blocks to jointly interpolate the target block. Since the smoothness of motion filed makes the motion vectors of 8-neighbor blocks around the interpolated block quite close to the true motion vector of the interpolated block, the proposed compensation algorithm has the better fault-tolerant capability than traditional ones. Besides, the annoying blocking artifacts can also be effectively suppressed by using overlapped blocks. Experimental results show that the proposed method is not only robust to motion vectors estimated wrongly, but also can to reduce blocking artifacts in comparison with existing popular compensation methods.

Correction of saturated current from measurement current transformer

The suggested study presents an easy and effective way to compensate for the distorted secondary current of measurement-type current transformers (CTs). The suggested compensating algorithm is based on estimating the magnetising current from a Frohlich hysteresis approach. The efficiency of the proposed technique was first proved using computer simulations. The prototype compensating device was then tested in a laboratory environment using a 5/1A, 10VA, C0,5 measurement-type CT. The proposed compensation algorithm is dependent on CT burden and X/R ratio of the line where CT is connected. The outcomes of the study demonstrate that the technique is able to reconstruct the secondary current with an acceptable error and can be applied to any measurement-type CT regardless of its size and winding topology.

Error compensation of four and five buckets wavefront extraction algorithms in phase-shifting interferometer

The phase-shifting method is all along an important wavefront extraction technique in the interferometer. Moreover, to require almost real-time measurement an algorithm with a small number of grabbed buckets is very helpful to the phase-shifting interferometer. Therefore, those algorithms within five buckets are very practical and are given more attention. In the paper, popular phase shifting algorithms within five buckets are compared and new four and five buckets algorithms are developed to compensate for two dominate error sources which are linear phase shift deviation and detector nonlinearity. Numerical simulations and wavefront extraction experiment verify that the proposed compensation algorithms are insensitive to linear phase shift deviation and detector nonlinearity compared with classical four and five bucket algorithm.

Metrological Performances of a Plantar Pressure Measurement System

Plantar pressure measurements provide useful information to diagnose a diverse range of foot disorders; unfortunately, the commercially available measurement systems are undesirably sensitive to several disturbances, but this aspect is mostly neglected in the literature. This paper describes the results of an experimental campaign aiming at the identification of pressure measuring system metrological performances, at system modeling, and at the implementation of correction procedures. The sensor model was implemented using the results of static and dynamic tests performed on a pedar-X plantar pressure measurement system. The static calibration was performed by analyzing the effect of temperature, single sensor coverage area, local curvature, tangential forces, long-term stability (creep), and sensor crosstalk on the system performances. The dynamic calibration was performed on an electrodynamic shaker, identifying the single sensor frequency response function and the hysteresis under different average loads. The dynamic sensor model is based on the Kelvin-Voigt model, which is representative of the viscoelastic behavior of the material. The model allowed us to compensate both the creep (i.e., the behavior under static loads) and the nonunitary frequency response function. A deconvolution-based algorithm has been proposed to compensate the sensor crosstalk effects, although its implementation requires additional investigations. Experimental results of bobbing and gait tests showed that, with the adoption of the proposed compensation algorithms, the force and center of pressure errors could be reduced by more than 50% of their initial values.

High Performance of Matrix Converter Fed Induction Motor for IPF Compensation by Using New DSVM Method

In the matrix converter (MC) system to improve the input current quality with low harmonic components, as well as to reduce the input voltage distortion supplied to the MC by using input filters. The major consequence of the paper is about the inter harmonics appearing in the induction motor drive.. In this paper, we propose a new direct space vector modulation (DSVM) method to achieve the required displacement angle between the input voltage and input current of the MC. The paper illustrates the various inter harmonics elimination methods of SVM inverter fed drive and the associated drawbacks. The drawbacks are eliminated by using New DSVM method instead of SVM method in matrix converter fed induction motor drive. A new switching strategy is introduced based on the maximum compensated angle. Then, power factor compensation algorithms using the new DSVM method to achieve the maximum IPF. In which Compensation algorithm is subsequently proposed using a proportional-integral controller to overcome drawbacks presented in compensation algorithm of SVM method. Simulation and experimental results are shown to validate the effectiveness of the proposed compensation algorithms. Keywords: Direct space vector modulation (DSVM) method, induction motor drive, inter-harmonics, input filter, matrix converter (MC).

Position-based compensation of electromagnetic fields interference for electromagnetic locomotive microrobot

Recently, the locomotion of a microrobot wirelessly actuated by electromagnetic actuation systems has been studied in many ways. Because of the inherent characteristics of an electromagnetic field, however, the magnetic field of each coil in the electromagnetic actuation system induces magnetic field interferences, which can distort the desired electromagnetic field, preventing the microrobot from following the desired path. In this article, we used two pairs of Helmholtz coils and two pairs of Maxwell coils in a two-dimensional electromagnetic actuation system. Generally, the two pairs of Helmholtz coils generate the torque for the rotation of the microrobot and the two pairs of Maxwell coils generate the propulsion force of the microrobot. Both pairs of Helmholtz and Maxwell coils have to work to simultaneously align and propel the microrobot in a desired direction. In this situation, however, the electromagnetic fields produced by the Helmholtz coils can interfere with those produced by the Maxwell coils. This interference is closely dependent on the position of the microrobot in the region of interest inside the electromagnetic coils system. This means that the alignment direction and propulsion force of the microrobot can be distorted according to the position of the microrobot. Therefore, we propose a compensation algorithm for the electromagnetic field interference using the position information of the microrobot to correct the magnetic field interferences. First, the interference of an electromagnetic field obeying the Biot–Savart law is analyzed by numerical analysis. Second, a position-based compensation algorithm for the locomotion of a microrobot is proposed. Various locomotion tests of a microrobot verified that the proposed compensation algorithm could reduce the normalized average tracking error from 5.25% to 1.92%.

A particle counting system using the photodetector array of a CMOS image sensor

In this paper, a particle counting system using a CMOS image sensor is demonstrated. The system utilizes a linear photodetector array as a detection element. Therefore, the particles are detected by multiple detectors simultaneously, in contrast to a single detector in conventional particle counting devices, while maintaining the sensitivity. Another advantage of the proposed system is that particles are detected across the full-channel width which removes the need for a particle-focusing method. Also, the proposed system can easily be integrated with a microfluidic chip fabricated on a transparent substrate, as the counting system is attached under the microchannel and counts the particles optically. Detection of polystyrene microbeads has been tested at a flow rate of 5.15 mm s−1. For 21 measurements, the proposed system showed an average count error of 4.56% and a standard deviation of 3.06% using a proposed compensation algorithm. Potentially, the proposed system can detect even smaller particles simply by utilizing a higher resolution CMOS image sensor.

Design and compensation of second-order sub-sampling digital frontend

The problem of designing a digital frontend (DFE) was considered which can dynamically access or sense dual bands in any radio frequency (RF) regions without requiring hardware changes. In particular, second-order bandpass sampling (BPS) as a technique that enables to realize the multiband reception function was discussed. In a second-order BPS system, digital reconstruction filters were utilized to eliminate the interferences generated while down converting arbitrarily positioned RF-band signals by using the direct digitization method. However, the inaccuracy in the phase shift or the amplitude mismatch between the two sample streams may cause insufficient rejection of interference. Practical problems were studied, such as performance degradation in signal-to-interference ratio (SIR) and compensation methods to overcome them. In order to demonstrate the second-order BPS as a flexible DFE suitable for software-defined radio (SDR) or cognitive radio (CR), a DFE testbed with a reconfigurable structure was implemented. Moreover, with a view to further demonstrate the proposed compensation algorithms, experimental results show that dual bands are received simultaneously.

Feed-Forward Compensator of Operating Frequency for APWM HB Flyback Converter

A feed-forward frequency compensator for an asymmetrical pulsewidth modulated (APWM) half-bridge (HB) flyback converter is proposed to increase its power conversion efficiency. Under a variable input voltage, the APWM HB flyback converter cannot be satisfied with the zero-current switching (ZCS) condition of output rectifiers because the variation of the turn-ON duration of main switches, which regulate the output voltage, induces their improper turn-OFF duration. This means that the resonance of a primary current during the turn-OFF of the switches is out of the ZCS operation of the output rectifiers. To avoid this improper operation, the resonant network should be designed with a marginal turn-OFF duration that guarantees the ZCS. However, this makes the converter operate with poor efficiency because of increasing conduction losses. The proposed feed-forward frequency compensator can properly change the converter's operating frequency to reduce the conduction losses according to the variation of the input voltage satisfying the ZCS condition of the output rectifiers. Operation principles, steady-state analysis, and soft-switching conditions are analyzed to derive the frequency compensation algorithm of the APWM HB flyback converter. Experimental results using a 240-W prototype converter show that the proposed compensation algorithm can improve the power conversion efficiency of the APWM HB flyback converter under the input-voltage variation.

A New Phase Noise and Channel Estimate Method in CO-OFDM System

High phase noise and low phase noise have been consideration in CO-OFDM systems, respectively. The hybrid mitigation algorithm is optimized to approach to high phase noise and low phase noise environment, and a hybrid half-blind phase noise compensation algorithm is proposed, which could be suitable to shifty DFB laser linewidth. 4QAM and 16QAM are used to modulate binary signal. The new proposed phase noise compensation algorithm is considered a mitigation method which has the ability of half-blind self-adaptation. It deduces the coefficient matrix in high and low phase noise compensation matrix and could improve performance under high or low modulation index situation.

Hysteresis in Piezoelectric Actuators: Modeling and Compensation

AbstractPiezoelectric stack actuators are characterized by their high resolution and precision in micro and nanometric displacements, being capable of very fast responses and reaching bandwidth ranges in the order of kHz. Consequently, these actuators are extensively used both for positioning and active vibration damping in demanding applications such as SPM (Scanning Probe Microscopy), AFM (Atomic Force Microscopy) or manufacturing systems for MEMS (Micro-Electro-Mechanical Systems). However, piezoelectric materials and actuators suffer from two important drawbacks, which have to be taken into account for effectively reaching the highest combination of precision and speed: hysteresis and rate dependence. In this paper, we describe a framework for modeling stack-based piezoelectric actuators using a Bond-Graph representation. The model considers the hysteresis nonlinearity and the rate-dependence, taking into account both direct and inverse piezoelectric effects. Based on this representation, and on the variation of the effective electrical capacitance of the actuator due to the hysteresis phenomenon, a compensation strategy is developed. Experimental results obtained with amplified piezoelectric actuators are introduced for validating the model, the identification strategy and the benefits of the proposed compensation algorithm in comparison with previously reported work in the literature.

Development of a compensation algorithm for a measurement current transformer

An exciting current resulted from the hysteresis characteristics of the core causes an error of a measurement current transformer (CT). To produce the high accuracy measurement CT, it is designed to minimise the exciting current. This requires a large cross-section of the core and the high permeability core. If the exciting current can be estimated exactly and compensated, the accuracy of the measurement CT can be improved significantly. This study describes the development of a compensation algorithm for a measurement CT. The proposed compensation algorithm decomposes the exciting current into the core-loss current and the magnetising current. The algorithm uses not the hysteresis curve but the flux-magnetising current curve to minimise the number of required curves for interpolation. The exciting current at every sampling interval is obtained by summing the core-loss current and the magnetising current and then added to the measured secondary current to obtain the correct primary current. The test results using Electromagnetic Transients Program (EMTP)-generated data indicate that the proposed algorithm can improve the accuracy of the measurement CT significantly even with a couple of the curves. The experimental test results indicate that the compensator can improve the accuracy of the CT significantly from 2.5 to 0.1%.

Input Power Factor Compensation Algorithms Using a New Direct-SVM Method for Matrix Converter

An input filter is necessary for a matrix converter (MC) system to improve the input current quality with low harmonic components, as well as to reduce the input voltage distortion supplied to the MC. However, the input filter's characteristics make the input power factor (IPF) obtained at unity only in the presence of high output loads, and the IPF degrades significantly under light-load conditions. In this paper, we propose a new direct space vector modulation (DSVM) method to achieve the required displacement angle between the input voltage and input current of the MC. A new switching strategy is introduced based on the maximum compensated angle. Then, power factor compensation algorithms using the new DSVM method to achieve the maximum IPF are presented, in which compensation algorithm I is based on using the input filter and power supply parameters to estimate the optimal compensated angle. Compensation algorithm II is subsequently proposed using a proportional-integral controller to overcome drawbacks presented in compensation algorithm I. Simulation and experimental results are shown to validate the effectiveness of the proposed compensation algorithms.

Analysis and compensation of i/q imbalance in MIMO transmit-receive diversity systems

In wireless communication systems, all in-phase and quadrature-phase (I/Q) signal processing receivers face the problem of I/Q imbalance. In this paper, we investigate the effect of I/Q imbalance on the performance of multiple-input multiple-output (MIMO) maximal ratio combining (MRC) systems that perform the combining at the radio frequency (RF) level, thereby requiring only one RF chain. In order to perform the MIMO MRC, we propose a channel estimation algorithm that accounts for the I/Q imbalance. Moreover, a compensation algorithm for the I/Q imbalance in MIMO MRC systems is proposed, which first employs the least-squares (LS) rule to estimate the coefficients of the channel gain matrix, beamforming and combining weight vectors, and parameters of I/Q imbalance jointly, and then makes use of the received signal together with its conjugation to detect the transmitted signal. The performance of the MIMO MRC system under study is evaluated in terms of average symbol error probability (SEP), outage probability and ergodic capacity, which are derived considering transmission over Rayleigh fading channels. Numerical results are provided and show that the proposed compensation algorithm can efficiently mitigate the effect of I/Q imbalance.