• Title/Summary/Keyword: Adaptive Combination

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Subband Adaptive Algorithm for Convex Combination of LMS based Transversal Filters (LMS기반 트랜스버설 필터의 컨벡스조합을 위한 부밴드 적응알고리즘)

  • Sohn, Sang-Wook;Lee, Kyeong-Pyo;Choi, Hun;Bae, Hyeon-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.1
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    • pp.133-139
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    • 2013
  • Convex combination of two adaptive filters is an efficient method to improve adaptive filter performances. In this paper, a subband convex combination method of two adaptive filters for fast convergence rate in the transient state and low steady state error is presented. The cost function of mixing parameter for a subband convex combination is defined, and from this, the coefficient update equation is derived. Steady state analysis is used to prove the stability of the subband convex combination. Some simulation examples in system identification scenario show the validity of the subband convex combination schemes.

A Study on Adaptive Control to Fill Weld Groove by Using Multi-Torches in SAW (SAW 용접시 다중 토치를 이용한 용접부 적응제어에 관한 연구)

  • 문형순;정문영;배강열
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.90-99
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    • 1999
  • Significant portion of the total manufacturing time for a pipe fabrication process is spent on the welding following primary machining and fit-up processes. To achieve a reliable weld bead appearance, automatic seam tracking and adaptive control to fill the groove are urgently needed. For the seam tracking in welding processes, the vision sensors have been successfully applied. However, the adaptive filling control of the multi-torches system for the appropriate welded area has not been implemented in the area of SAW(submerged arc welding) by now. The term adaptive control is often used to describe recent advances in welding process control by strictly this only applies to a system which is able to cope with dynamic changes in system performance. In welding applications, the term adaptive control may not imply the conventional control theory definition but may be used in the more descriptive sense to explain the need for the process to adapt to the changing welding conditions. This paper proposed various types of methodologies for obtaining a good bead appearance based on multi-torches welding system with the vision system in SAW. The methodologies for adaptive filling control used welding current/voltage, arc voltage/welding current/wire feed speed combination and welding speed by using vision sensor. It was shown that the algorithm for welding current/voltage combination and welding speed revealed sound weld bead appearance compared with that of voltage/current combination.

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A Study on Adaptive Control to Fill Weld GrooveBy Using Multi-Torches in SAW (SAW 용접시 다중 토치를 이용한 용접부 적응제어에 관한 연구)

  • 문형순;김정섭;권혁준;정문영
    • Proceedings of the KWS Conference
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    • 1999.10a
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    • pp.47-50
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    • 1999
  • The term adaptive control is often used to describe recent advances in welding process control but strictly this only applies to system which are able to cope with dynamic changes in system performance. In welding applications, the term adaptive control may not imply the conventional control theory definition but may be used in the more descriptive sense to explain the need for the process to adapt to the changing welding conditions. This paper proposed a methodology for obtaining a good bead appearance based on multi-torches welding system with the vision system in SAW. The methodologies for adaptive filling control used the welding current/voltage, arc voltage/welding current/wire feed speed combination and welding speed by using the vision sensor. It was shown that the algorithm for the welding current/voltage combination and welding speed revealed the sound weld bead appearance compared with that of the voltage/current combination.

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Suboptimal Adaptive Filters for Stochastic Systems with Multisensor Environment

  • Shin, Vladimir;Ahn, Jun-Il
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.2045-2050
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    • 2004
  • An optimal combination of arbitrary number correlated estimates is derived. In particular, for two estimates this combination represents the well-known Millman and Bar-Shalom-Campo formulae for uncorrelated and correlated estimation errors, respectively. This new result is applied to the various estimation problems as least-squares estimation, Kalman filtering, and adaptive filtering. The new approximate adaptive filter with a parallel structure is proposed. It is shown that this filter is very effective for multisensor systems containing different types of sensors. Examples demonstrating the accuracy of the proposed filter are given.

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A study on improvement of steady-state peformance and convergence rate in an adaptive noise canceller (적응잡음제거기의 정상상태 성능 및 수렴율 향상에 관한 연구)

  • 배종갑;김창기;박장식;손경식
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.4
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    • pp.42-49
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    • 1997
  • A conventional adaptive noise canceller (ANC) using LMS algorithm suffers from the misadjustment of adaptive filter weights due to the gradient-estimate noise by input speech signal at steady state. In this paper, an ANC is proposed which uses the combination of VSLMS (variable step size LMS) and SA (sign algorithm) to improve steady state performance and convergence rate. SA algorithm is applied in speech region to prevent the weights from perturbing by output speech of ANC and VSLMS algorithm is applied to improve convergence rate and channel tracking ability in silence region and adaptive transient region. In compute rsimulation, the performance of the proposed VSLMS-SA combination algorithm is much better than LMS algorithm and the algorithm, recently proposed by greenberg, with adaptation step-size parameter determine dby sum method in convergence rate, channel tracking and steady state performance.

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New Adaptive Linear Combination Structure for Tracking/Estimating Phasor and Frequency of Power System

  • Wattanasakpubal, Choowong;Bunyagul, Teratum
    • Journal of Electrical Engineering and Technology
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    • v.5 no.1
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    • pp.28-35
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    • 2010
  • This paper presents new Adaptive Linear Combination Structure (ADALINE) for tracking/estimating voltage-current phasor and frequency of power system. To estimate the phasors and frequency from sampled data, the algorithm assumes that orthogonal coefficients and speed of angular frequency of power system are unknown parameters. With adequate sampled data, the estimation problem can be considered as a linear weighted least squares (LMS) problem. In addition to determining the phasors (orthogonal coefficients), the procedure estimates the power system frequency. The main algorithm is verified through a computer simulation and data from field. The proposed algorithm is tested with transient and dynamic behaviors during power swing, a step change of frequency upon islanding of small generators and disconnection of load. The algorithm shows a very high accuracy, robustness, fast response time and adaptive performance over a wide range of frequency, from 10 to 2000 Hz.

Fuzzy Rules Optimizing by Neural Network-based Adaptive Fuzzy Control

  • K, K.-Wong;Akio, Katuki
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.96.2-96
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    • 2001
  • This paper presents a control method for the experimental mobile vehicle. By merging the advantages of neural network, adaptive and fuzzy control, neural network-based adaptive fuzzy control is proposed. It can deal with a large amount of training data by neural network, from these data producing more accurate fuzzy rules by adaptive control, and then controlling the object by fuzzy control. This is not the simple combination of the three methods, but merging them into one control system Experiments and some future considerations are given.

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Performance of Adaptive Modulation and Coding with Transmit Diversity in Rayleigh fading Channel (레일리 페이딩 채널에서 전송 안테나 다이버시티 기법을 적용한 Adaptive Modulation and Coding의 성능 분석)

  • 김인경;김주응;강창언;홍대식
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.73-76
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    • 2001
  • A key requirement for packet based wireless communication systems is to provide a high data rate packet service and improved throughput. To achieve a high throughput, adaptive methods for adjustment of the modulation and coding can be used. In this paper, we propose and analyze a scheme which is a combination of an adaptive modulation and coding(AMC) and transmit diversity(TD). Two different TD schemes are analysed: STTD and STD. Proposed system provides significant improvement in the average throughput.

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Improved Particle Swarm Optimization Algorithm for Adaptive Beam Forming System (적응형 빔 형성 시스템을 위한 개선된 개체 군집 최적화 알고리즘)

  • Jung, Jin-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.13 no.3
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    • pp.587-592
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    • 2018
  • An adaptive beam forming system using a phased array antenna improves communication quality by beam forming adaptively to a communication environment having an interference signal. For adaptive beam forming, a good combination of the phases of the excited signals to each radiating element of the phased array antenna should be calculated. In this paper, improved particle swarm optimization algorithm that adds a re-spreading procedure according to particle density was proposed to increase the probability of good phase shift combination output.

Cooperative Spectrum Sensing using Kalman Filter based Adaptive Fuzzy System for Cognitive Radio Networks

  • Thuc, Kieu-Xuan;Koo, In-Soo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.1
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    • pp.287-304
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    • 2012
  • Spectrum sensing is an important functionality for cognitive users to look for spectrum holes before taking transmission in dynamic spectrum access model. Unlike previous works that assume perfect knowledge of the SNR of the signal received from the primary user, in this paper we consider a realistic case where the SNR of the primary user's signal is unknown to both fusion center and cognitive radio terminals. A Kalman filter based adaptive Takagi and Sugeno's fuzzy system is designed to make the global spectrum sensing decision based on the observed energies from cognitive users. With the capacity of adapting system parameters, the fusion center can make a global sensing decision reliably without any requirement of channel state information, prior knowledge and prior probabilities of the primary user's signal. Numerical results prove that the sensing performance of the proposed scheme outperforms the performance of the equal gain combination based scheme, and matches the performance of the optimal soft combination scheme.