• 제목/요약/키워드: Linearization Method

검색결과 484건 처리시간 0.028초

DWT 및 전치 왜곡기를 이용한 볼테라 시스템 선형화 (On the Linearization of Volterra Nonlinear Systems using DWT and a Predistorter)

  • 강동준;김영근;남상원
    • 대한전자공학회:학술대회논문집
    • /
    • 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
    • /
    • pp.553-556
    • /
    • 2000
  • This paper proposes an adaptive linearization method of Volterra nonlinear systems using DWT(Discrete Wavelet Transform)and an LMS-type predistorter. In particular, the proposed wavelet transform-domain lineatization method leads to diagonalization of the input vector auto-correlation matrix which yields improvement of the convergence rate of the corresponding transform-domain LMS algorithm. Furthermore, the adaptive Volterra predistorter followed by a corresponding weakly Volterra nonlinear system(here. a TWT amplifier model in a satellite communication system) is utilized to compensate for the distortion in the output. Also,12-PSK and 4-QAM are applied as the input to the nonlinear system to be tested. Some simulation results show that the proposed linearization approach has better performance than DCT-based or conventional normalized LMS algorithms do.

  • PDF

Nonlinear impact of negative stiffness dampers on stay cables

  • Shi, Xiang;Zhu, Songye
    • Structural Monitoring and Maintenance
    • /
    • 제5권1호
    • /
    • pp.15-38
    • /
    • 2018
  • Negative stiffness dampers (NSDs) have been proven an efficient solution to vibration control of stay cables. Although previous studies usually assumed a linear negative stiffness behavior of NSDs, many negative stiffness devices produce negative stiffness with nonlinear behavior. This paper systematically evaluates the impact of nonlinearity in negative stiffness on vibration control performance for stay cables. A linearization method based on energy equivalent principle is proposed, and subsequently, the impact of two types of nonlinear stiffness, namely, displacement hardening and softening stiffness, is evaluated. Through the Hilbert transform (HT) of free vibration responses, the effects of nonlinear stiffness of an NSD on the modal frequencies, damping ratios and frequency response functions of a stay cable is also investigated. The HT analysis results validate the accuracy of the linearization method.

Dynamic Range Improvement of IM-DD Optical Link using Dual-Wavelength Dual-Parallel Modulation

  • Li, Xianghua;Yang, Chun;Zhou, Zhenghua;Chong, Yuhua
    • Journal of the Optical Society of Korea
    • /
    • 제18권4호
    • /
    • pp.330-334
    • /
    • 2014
  • In this paper, we present an incoherent dual-parallel modulation linearized optical link employing two different optical wavelengths. Comparing with previous dual-parallel modulation, this linearization method prevents the recreation of distortion products and can be readily implemented. Furthermore, a dual-wavelength dual-parallel modulation linearized optical link constructed with the commercially available devices is experimentally demonstrated with a spurious-free dynamic range of $122.5dB.Hz^{4/5}$. More than 25 dB suppression of the intermodulation distortion, 15.6 dB improvement of spurious-free dynamic range and 1.5 dB improvement of compression dynamic range are achieved after linearization.

Heave Compensation System Design for Offshore Crane based on Input-Output Linearization

  • Le, Nhat-Binh;Kim, Byung-Gak;Kim, Young-Bok
    • 동력기계공학회지
    • /
    • 제21권2호
    • /
    • pp.27-34
    • /
    • 2017
  • A heave motion of the offshore crane system with load is affected by unpredictable external factors. Therefore the offshore crane must satisfy rigorous requirements in terms of safety and efficiency. This paper intends to reduce the heave displacement of load position which is produced by rope extension and sea wave disturbance in vertical motion. In this system, the load position is compensated by the winch actuator control. The rope is modeled as a mass-damper-spring system, and a controller is designed by the input-output linearization method. The model system and the proposed control method are evaluated on the simulation results.

거리 정보를 이용한 되먹음 선형화 기법 무인기 편대 비행제어 (Multi-UAV Formation Based on Feedback Linearization Technique Using Range-Only Measurement)

  • 김성환;유창경;박춘배
    • 제어로봇시스템학회논문지
    • /
    • 제15권1호
    • /
    • pp.23-30
    • /
    • 2009
  • This paper addresses how to make a formation of multiple unmanned aerial vehicles (UAVs) using only the relative range information. Since the relative range can easily be measured by an on-board range sensor like the laser range finder, the proposed method does not require any expensive and heavy wireless communication system to share the navigation information of each vehicle. Based on the two-dimensional (2-D) nonlinear equations of motion, we propose a nonlinear formation controller using the typical input-output feedback linearization method. The performance of the proposed formation controller is verified by various numerical simulations.

자기부상 시스템의 PID 제어와 Feedback Linearization 제어와의 성능비교 (Comparison of PID and Feedback Linearization Control for Magnetic Levitation System)

  • 박종석;김동환
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
    • /
    • pp.263-263
    • /
    • 2000
  • Electromagnetic Suspension(EMS) System produces no noise, friction and heat through non-contacting operation Therefore, the applicable device using EMS system has a lot of attraction in case of the high-speed and non-contacting transmission EMS with nonlinear properties requires a precise airgap position control and stable kinematics characteristics under the disturbances, In this study, the nonlinear system was linearized by a Nonlinear Feedback Lineariztion(NFL) method. The NFL method requires that the modelling should be exact, and the state variables should be measured and a rapidly operating controller be necessary on account of a heavy data calculating In the experiments. the ideal control characteristics of the NFL was acquired through simulation at first. then the characteristics of the actual system were compared with those of simulation. In addition, the results by NFL were examined and analysed considering the characteristics of the PID control. The Control by NFL shows much stable control characteristics than the PID control. Whereas, the steady state errors occur for various disturbances. hence a robust control design is remained for a further study.

  • PDF

Integrated equations of motion for direct integration methods

  • Chang, Shuenn-Yih
    • Structural Engineering and Mechanics
    • /
    • 제13권5호
    • /
    • pp.569-589
    • /
    • 2002
  • In performing the dynamic analysis, the step size used in a step-by-step integration method might be much smaller than that required by the accuracy consideration in order to capture the rapid chances of dynamic loading or to eliminate the linearization errors. It was first found by Chen and Robinson that these difficulties might be overcome by integrating the equations of motion with respect to time once. A further study of this technique is conducted herein. This include the theoretical evaluation and comparison of the capability to capture the rapid changes of dynamic loading if using the constant average acceleration method and its integral form and the exploration of the superiority of the time integration to reduce the linearization error. In addition, its advantage in the solution of the impact problems or the wave propagation problems is also numerically demonstrated. It seems that this time integration technique can be applicable to all the currently available direct integration methods.

개선 구산 계측함수에 의한 디지털 계측시스템의 정밀도 향상 (Accuracy Improvement of Digital Measurement System by Modified Piecewise Measuring Functions)

  • 홍성훈;강문성
    • 제어로봇시스템학회논문지
    • /
    • 제7권2호
    • /
    • pp.138-145
    • /
    • 2001
  • Measurement errors in a digital measurement systems are mainly due to the consisting elements accuracies and the circuit parameters changes following the environment variations such as temperature. Further, systems non-linearity makes the measurement accuracy worse, and accordingly a linearization method should be considered to avoid this worsening. In this study, a temperature error-correction method and linearization methods are proposed and a digital temperature measurement system utilizing these methods is realized. And the proposed measurement methods are observed to increase the measurement accuracy of the digital measurement system.

  • PDF

Load Position and Residual Vibration Control of an Offshore Crane System Based on Input-Output Linearization Theory

  • Le, Nhat-Binh;Lee, Kwon-Soon;Kim, Young-Bok
    • 한국항해항만학회지
    • /
    • 제41권5호
    • /
    • pp.337-344
    • /
    • 2017
  • In the offshore crane system, the requirements on the operating safety are extremely high due to many external factors. Rope extension is one of the factors producing vertical vibration of load. In this study, the load is carried by the motor-winch actuator control and the rope is modeled as a mass-damper-spring system. To control the load position and suppress the vertical vibration of the load, a control system based on input-output linearization method is proposed. By the simulation and experiment results with pilot crane model, the effectiveness of proposed control method is evaluated and verified.

전력계통안정화를 위한 간접적응 비선형제어 (Indirect adaptive nonlinear control for power system stabilization)

  • 이도관;윤태웅;이병준
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
    • /
    • pp.454-457
    • /
    • 1997
  • As in most industrial processes, the dynamic characteristics of an electric power system are subject to changes. Amongst those effects which cause the system to be uncertain, faults on transmission lines are considered. For the stabilization of the power system, we present an indirect adaptive control method, which is capable of tracking a sudden change in the effective reactance of a transmission line. As the plant dynamics are nonlinear, an input-output feedback linearization method equipped with nonlinear damping terms is combined with an identification algorithm which estimates the effect of a fault. The stability of the resulting adaptive nonlinear system is investigated.

  • PDF