• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.29-32
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• 2001

This paper has simulated the PER(Packet Error Rate), ratio of received packet and payload BER of Bluetooth system with packet types of ACL(Asynchronous Connection Less) and SCO(Synchronous Connection Oriented) link over wireless Ad-hoc environment. AWGN(Additive White Gaussian Noise) and Rayleigh fading are considered as channel model, and the analysis is based on the baseband model of Bluetooth system. In terms of PER and ratio of received packet, performance of DM1 packet is almost same as those of HV1, HV2 and HV3 packets, the performances of the other packets depend on the packet types. In terms of payload BER performance, there is no difference among HV2 packet of SCO link and DM1, DM3, DM5 packets of ACL link. Moreover, there is no difference among HV3 packet of SCO link and DM1, DM3, DM5 packets of ACL link, too.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.559-564
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• 1993

Nonlinear equation of motion of the flexible manipulator are derived by the Lagrangian method in symbolic form to better understand the structure of the dynamic model. The resulting equations of motion have a structure which is useful to reduce the number of terms calculated, to check correctness, or to extend the model to high order. A manipulator with a flexible 4 bar link mechanism is a constrained system whose equations are sensitive to numerical integration error. This constrained system is solved using the null space matrix of the constraint Jacobian matrix. Singular value decomposition is a stable algorithm to find the null space matrix.

• Journal of Power Electronics
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• 제14권6호
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• pp.1178-1188
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• 2014

This study proposes a finite-state model predictive controller to regulate the load current and balance the DC-link capacitor voltages of a four-leg neutral-point-clamped converter. The discrete-time model of the converter, DC-link, inductive filter, and load is used to predict the future behavior of the load currents and the DC-link capacitor voltages for all possible switching states. The switching state that minimizes the cost function is selected and directly applied to the converter. The cost function is defined to minimize the error between the predicted load currents and their references, as well as to balance the DC-link capacitor voltages. Moreover, the current regulation performance is improved by using a two-step prediction horizon. The feasibility of the proposed predictive control scheme for different references and loads is verified through real-time implementation on the basis of dSPACEDS1103.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.637-648
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• 2007

This paper presents a sensor fusion method based on indirect Kalman filter(IKF) for error compensation of low-cost inertial sensors and its application to the determination of attitude and position of small flying robots. First, the analysis of the measurement error characteristics to zero input is performed, focusing on the bias due to the temperature variation, to derive a simple nonlinear bias model of low-cost inertial sensors. Moreover, from the experimental results that the coefficients of this bias model possess non-deterministic (stochastic) uncertainties, the bias of low-cost inertial sensors is characterized as consisting of both deterministic and stochastic bias terms. Then, IKF is derived to improve long term stability dominated by the stochastic bias error, fusing low-cost inertial sensor measurements compensated by the deterministic bias model with non-inertial sensor measurement. In addition, in case of using intermittent non-inertial sensor measurements due to the unreliable data link, the upper and lower bounds of the state estimation error covariance matrix of discrete-time IKF are analyzed by solving stochastic algebraic Riccati equation and it is shown that they are dependant on the throughput of the data link and sampling period. To evaluate the performance of proposed method, experimental results of IKF for the attitude determination of a small flying robot are presented in comparison with that of extended Kaman filter which compensates only deterministic bias error model.

• 제어로봇시스템학회논문지
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• 제12권11호
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• pp.1081-1087
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• 2006

Generally, biped walking is difficult to control because a biped robot is a nonlinear system with various uncertainties. In this paper, we propose a hybrid sliding-mode control method using a WNN uncertainty observer for stable walking of the 5-link biped robot with model uncertainties and the external disturbance. In our control system, the sliding mode control is used as main controller for the stable walking and a wavelet neural network(WNN) is used as an uncertainty observe. to estimate uncertainties of a biped robot model, and the error compensator is designed to compensate the reconstruction error of the WNN. The weights of WNN are trained by adaptation laws that are induced from the Lyapunov stability theorem. Finally, the effectiveness of the proposed control system is verified through computer simulations.

• 대한산업공학회지
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• 제31권3호
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• pp.219-227
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• 2005

In this paper, an optimal power and rate allocation model is mathematically formulated on the forward link of multicell CDMA mobile systems. The model maximizes total utility considering data rates and fairness among cells under delay and PRER (Post RPL Error Rate) constraints. The two-level power and rate allocation scheme is suggested to solve the proposed model. Experimental results show that the proposed scheme provides a good solution in a fast time.

• 융합정보논문지
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• 제10권5호
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• pp.1-7
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• 2020

본 논문은 수중 IoT 네트워크에서 센서의 전력 소비를 줄이고 네트워크의 처리량을 향상하는 수중 링크적응 방법을 제안한다. 링크 적응 방법의 하나인 AMC(Adaptive Modulation and Coding) 기술은 SNR(Signal Noise Rate)과 BER(Bit Error Rate)의 강한 상관관계를 이용하지만, 수중에 바로 적용하는 것은 어렵다. 따라서 수중 환경에 적합한 머신러닝 기반의 AMC 기술을 제안한다. 제안하는 MCS(Modulation Coding and Scheme) 예측 모델은 수중 채널 환경에서 목표 BER 값을 달성하기 위한 통신 방법을 예측한다. 예측된 통신 방법을 실제 수중 무선 통신에서 적용하는 것은 현실적으로 어렵기 때문에 본 논문에서는 높은 정확도의 BER 예측 모델을 사용해 MCS 예측 모델의 성능을 확인한다. 결과적으로 제안하는 AMC 기술은 통신 성공 확률을 올림으로써 머신러닝의 적용 가능성을 확인시켰다.

• 대한전기학회논문지
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• 제43권5호
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• pp.838-847
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• 1994

Although there is an analytical proof of modeling capability of the neural network, the convergency error in nonlinearity modeling is inevitable, since the steepest descent based practical larning algorithms do not guarantee the convergency of modeling error. Therefore, it is difficult to apply the neural network to control system in critical environments under an on-line learning scheme. Although the convergency of modeling error of a neural network is not guatranteed in the practical learning algorithms, the convergency, or boundedness of tracking error of the control system can be achieved if a proper feedback control law is combined with the neural network model to solve the problem of modeling error. In this paper, the neural network is introduced for compensating a system uncertainty to control a nonlinear dynamic system. And for suppressing inevitable modeling error of the neural network, an iterative neural network learning control algorithm is proposed as a virtual on-line realization of the Adaptive Variable Structure Controller. The efficiency of the proposed control scheme is verified from computer simulation on dynamics control of a 2 link robot manipulator.

• 한국항행학회논문지
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• 제6권1호
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• pp.77-83
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• 2002

무선 접속 방식으로 블루투스의 출현은 즉석에서 전자기기들을 ad-hoc 망으로 다룰 수 있도록 하였다. 이러한 근거리 ad-hoc 무선망을 피코넷이라고 부르며 무허가 2.45 GHz ISM(Industrial, Scientific, Medical) 대역에서 운용된다. 본 논문에서는 무선 ad-hoc 환경에서 블루투스 ACL/SCO(Asynchronous Connection Less/Synchronous Connection Oriented) 링크의 패킷 형태에 따른 피코넷의 PER(Packet Error Rate), 패킷수신율, 페이로드 BER (Bit Error Rate)을 시뮬레이션하였다. 채널 모델로서 레일리 페이딩의 영향이 고려되었고 불루투스 기저대역 규격에 따라서 시뮬레이션하였다. 시뮬레이션 결과로부터 불루투스 피코넷의 PER과 처리율은 ACL/SCO 링크의 패킷 형태에 민감하다는 것을 알 수 있었다.

• 한국항행학회논문지
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• 제9권2호
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• pp.156-163
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• 2005

본 논문에서는 ICAO (International Civil Aviation Organization)에서 규정한 VDL 모드 3 시스템 계통도와 제원을 구성하여 BER(Bit Error Rate), 전송지연시간, 버스트 재전송율, 그리고 throughput에 대한 성능을 분석하였다. 성능 분석 결과, BER과 전송지연시간, throughput, 버스트 재전송율의 관계를 명확히 정의할 수 있었고, 또한 down link에서 V/D 재전송율과 throughput에 강한 상관이 있음이 판명되었다.