• Title/Summary/Keyword: robust adaptive control

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Improving User Satisfaction in Adaptive Multicast Video

  • de Amorim, Marcelo Dias;Duarte, Otto Carlos M.B.;Pujolle, Guy
    • Journal of Communications and Networks
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    • v.4 no.3
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    • pp.221-229
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    • 2002
  • Adaptability is the most promising feature to be applied in future robust multimedia applications. In this paper, we propose the Direct Algorithm to improve the degree of satisfaction at heterogeneous receivers in multi-layered multicast video environments. The algorithm relies on a mechanism that dynamically controls the rates of the video layers and is based on feedback control packets sent by the receivers. The algorithm also addresses scalability issues by implementing a merging procedure at intermediate nodes in order to avoid packet implosion at the source in the case of large multicast groups. The proposed scheme is optimized to achieve high global video quality and reduced bandwidth requirements. We also propose the Direct Algorithm with a virtual number of layers. The virtual layering scheme induces intermediate nodes to keep extra states of the multicast session, which reduces the video degradation for all the receivers. The results show that the proposed scheme leads to improved global video quality at heterogeneous receivers with no cost of extra bandwidth.

Parameter Estimation of Induction Motor using Neural Network Theory (신경망이론을 이용한 유도전동기 파라미터 추정)

  • Oh, Won-Seok
    • Journal of the Korean Institute of Telematics and Electronics T
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    • v.35T no.2
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    • pp.56-65
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    • 1998
  • In this paper, a neural network(NN) control system is proposed and practically implemented, which is adequate to the induction motor speed control system with frequent load variation. The back propagation neural network technique is used to provide a real adaptive estimation of the motor parameter. The error between the desired state variable and the actual one is back-propagated to adjust the motor parameter, so that the actual state variable will coincide with the desired one. Designed control system is based on PC-DSP structure for the purposed of easiness of applying NN algorithm. Through computer simulation and experimental results, it is verified that proposed control system is robust to the load variation and practical implementation is possible.

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MRAS Speed Estimator Based on Type-1 and Type-2 Fuzzy Logic Controller for the Speed Sensorless DTFC-SVPWM of an Induction Motor Drive

  • Ramesh, Tejavathu;Panda, Anup Kumar;Kumar, S. Shiva
    • Journal of Power Electronics
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    • v.15 no.3
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    • pp.730-740
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    • 2015
  • This paper presents model reference adaptive system speed estimators based on Type-1 and Type-2 fuzzy logic controllers for the speed sensorless direct torque and flux control of an induction motor drive (IMD) using space vector pulse width modulation. A Type-1 fuzzy logic controller (T1FLC) based adaptation mechanism scheme is initially presented to achieve high performance sensorless drive in both transient as well as in steady-state conditions. However, the Type-1 fuzzy sets are certain and cannot work effectively when a higher degree of uncertainties occurs in the system, which can be caused by sudden changes in speed or different load disturbances and, process noise. Therefore, a new Type-2 FLC (T2FLC) - based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties, improve the performance, and is also robust to different load torque and sudden changes in speed conditions. The detailed performance of different adaptation mechanism schemes are performed in a MATLAB/Simulink environment with a speed sensor and sensorless modes of operation when an IMD is operates under different operating conditions, such as no-load, load, and sudden changes in speed. To validate the different control approaches, the system is also implemented on a real-time system, and adequate results are reported for its validation.

Bayesian Inference driven Behavior-Network Architecture for Intelligent Agent to Avoid Collision with Moving Obstacles (지능형 에이전트의 움직이는 장애물 충돌 회피를 위한 베이지안 추론 주도형 행동 네트워크 구조)

  • 민현정;조성배
    • Journal of KIISE:Software and Applications
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    • v.31 no.8
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    • pp.1073-1082
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    • 2004
  • This paper presents a technique for an agent to adaptively behave to unforeseen and dynamic circumstances. Since the traditional methods utilized the information about an environment to control intelligent agents, they were robust but could not behave adaptively in a complex and dynamic world. A behavior-based method is suitable for generating adaptive behaviors within environments, but it is necessary to devise a hybrid control architecture that incorporates the capabilities of inference, learning and planning for high-level abstract behaviors. This Paper proposes a 2-level control architecture for generating adaptive behaviors to perceive and avoid dynamic moving obstacles as well as static obstacles. The first level is behavior-network for generating reflexive and autonomous behaviors, and the second level is to infer dynamic situation of agents. Through simulation, it has been confirmed that the agent reaches a goal point while avoiding static and moving obstacles with the proposed method.

Congestion Control Scheme for Efficient Multimedia Transmission in Broadband Wireless Networks (광대역 무선 네트워크에서 효율적인 멀티미디어 전송을 위한 혼잡 제어 기법)

  • Lee, Eunjae;Chung, Kwangsue
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.7
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    • pp.1599-1609
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    • 2014
  • TCP does not ensure the bandwidth and delay bound required for multimedia streaming services in broadband wireless network environments. In this paper, we propose a new congestion control scheme for efficient multimedia transmission, called COLO TCP (Concave Increase Slow Start Logarithmic Increase Congestion Avoidance TCP). The COLO TCP prevents the burst packet loss by applying the concave increase algorithm in slow start phase. In the congestion avoidance phase, COLO TCP uses the logarithmic increase algorithm that quickly recovers congestion window after packet loss. To highly utilize network bandwidth and reduce packet loss ratio, COLO TCP uses additive increase algorithm and adaptive decrease algorithm. Through simulation results, we prove that our COLO TCP is more robust for random loss. It is also possible for efficient multimedia transmission.

Noise-robust electrocardiogram R-peak detection with adaptive filter and variable threshold (적응형 필터와 가변 임계값을 적용하여 잡음에 강인한 심전도 R-피크 검출)

  • Rahman, MD Saifur;Choi, Chul-Hyung;Kim, Si-Kyung;Park, In-Deok;Kim, Young-Pil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.12
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    • pp.126-134
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    • 2017
  • There have been numerous studies on extracting the R-peak from electrocardiogram (ECG) signals. However, most of the detection methods are complicated to implement in a real-time portable electrocardiograph device and have the disadvantage of requiring a large amount of calculations. R-peak detection requires pre-processing and post-processing related to baseline drift and the removal of noise from the commercial power supply for ECG data. An adaptive filter technique is widely used for R-peak detection, but the R-peak value cannot be detected when the input is lower than a threshold value. Moreover, there is a problem in detecting the P-peak and T-peak values due to the derivation of an erroneous threshold value as a result of noise. We propose a robust R-peak detection algorithm with low complexity and simple computation to solve these problems. The proposed scheme removes the baseline drift in ECG signals using an adaptive filter to solve the problems involved in threshold extraction. We also propose a technique to extract the appropriate threshold value automatically using the minimum and maximum values of the filtered ECG signal. To detect the R-peak from the ECG signal, we propose a threshold neighborhood search technique. Through experiments, we confirmed the improvement of the R-peak detection accuracy of the proposed method and achieved a detection speed that is suitable for a mobile system by reducing the amount of calculation. The experimental results show that the heart rate detection accuracy and sensitivity were very high (about 100%).

Bezier Curve-Based Path Planning for Robust Waypoint Navigation of Unmanned Ground Vehicle (무인차량의 강인한 경유점 주행을 위한 베지어 곡선 기반 경로 계획)

  • Lee, Sang-Hoon;Chun, Chang-Mook;Kwon, Tae-Bum;Kang, Sung-Chul
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.5
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    • pp.429-435
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    • 2011
  • This paper presents a sensor fusion-based estimation of heading and a Bezier curve-based motion planning for unmanned ground vehicle. For the vehicle to drive itself autonomously and safely, it should estimate its pose with sufficient accuracy in reasonable processing time. The vehicle should also have a path planning algorithm that enables to adapt to various situations on the road, especially at intersections. First, we address a sensor fusion-based estimation of the heading of the vehicle. Based on extended Kalman filter, the algorithm estimates the heading using the GPS, IMU, and wheel encoders considering the reliability of each sensor measurement. Then, we propose a Bezier curve-based path planner that creates several number of path candidates which are described as Bezier curves with adaptive control points, and selects the best path among them that has the maximum probability of passing through waypoints or arriving at target points. Experiments under various outdoor conditions including at intersections, verify the reliability of our algorithm.

RVEGA SMC for Precise Level Control of Coupled Tank System (이중 탱크 시스템의 정밀 수위 제어를 위한 RVEGA SMC에 관한 연구)

  • 김태우;이준탁
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.13 no.4
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    • pp.102-108
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    • 1999
  • The sliding rmde controller(SMC) is known as having the robust variable structures for the nonlinear control systems such as coupled tank system with the pararretric perturbations and with the rapid disturbances. But the adaptive tuning algorit1uns for their pararreters are not satisfactory. Therefore, in this paper, a Real Variable Elitist Genetic Algorithm based Sliding Mode Controller (RVEGA SMC) for the precise control of the coupled tank level was tried. The SMC's switching pararreters were optimized easily and rapidly by RVEGA The simulation results showed that the tank level could be satisfactorily controlled without any overshoot and any steady-state error by the proposed RVEGA SMC.GA SMC.

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Real Time Road Lane Detection with RANSAC and HSV Color Transformation

  • Kim, Kwang Baek;Song, Doo Heon
    • Journal of information and communication convergence engineering
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    • v.15 no.3
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    • pp.187-192
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    • 2017
  • Autonomous driving vehicle research demands complex road and lane understanding such as lane departure warning, adaptive cruise control, lane keeping and centering, lane change and turn assist, and driving under complex road conditions. A fast and robust road lane detection subsystem is a basic but important building block for this type of research. In this paper, we propose a method that performs road lane detection from black box input. The proposed system applies Random Sample Consensus to find the best model of road lanes passing through divided regions of the input image under HSV color model. HSV color model is chosen since it explicitly separates chromaticity and luminosity and the narrower hue distribution greatly assists in later segmentation of the frames by limiting color saturation. The implemented method was successful in lane detection on real world on-board testing, exhibiting 86.21% accuracy with 4.3% standard deviation in real time.

Robust Disturbance Compensation for Servo Drives Fed by a Matrix Converter

  • Park, Ki-Woo;Chwa, Dong-Kyoung;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.9 no.5
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    • pp.791-799
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    • 2009
  • This paper presents a time-varying sinusoidal disturbance compensation method (based on an adaptive estimation scheme) for induction motor drives fed by a matrix converter. In previous disturbance accommodation methods, sinusoidal disturbances with unknown time-invariant frequencies have been considered. However, in the new method proposed here, disturbances with unknown time-varying frequencies are considered. The disturbances can be estimated by using a disturbance accommodating observer, and an additional control input is added to the induction machine drive. The stability analysis is carried out considering the disturbance estimation error and simulation results are shown to illustrate the performance of the proposed solution.