• 제목/요약/키워드: Delay Tracking

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Adaptive Feedforward Rejection of Microactuator Resonance in Hard Disk Drive Dual-stage Actuator Servo (하드디스크 드라이브 마이크로 구동기의 공진 영향 제거를 위한 적응 피드포워드 제어)

  • Oh, Dong-Ho;Lee, Seung-Hi;Baek, Sang-Eun;Na, Hee-Seung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1596-1600
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    • 2000
  • We propose a novel adaptive feed forward controller (AFC) design method for rejecting the effect of micro actuator resonance in the design of dual-stage actuator servo systems for disk drives. Microactuator's resonance is one of important issues in dual-stage actuator servo, which varies up to ${\pm}10%$ per product and even during operation. We derive an adaptive algorithm for the proposed AFC design, which turns out to be identical to the delayed-x LMS algorithm which is a special form of the filtered-x LMS algorithm. In the algorithm, coefficients of the AFC are adapted by the residuals of constrained structure defined in such a way that the coefficients become time invariant. Contrary to the conventional AFC, it considers the phase delay of closed-loop transfer function at resonance frequency for system stability. We also apply an adaptive algorithm with frequency tracking capability. The frequency tracking algorithm is induced by the orthogonality of AFC coefficients. Computer simulations are carried out to demonstrate effect of the proposed AFCs.

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A Rejection of Harmonic Ripples for d-q Transformation (d-q 변환에서의 고조파 맥동 제거)

  • Choi, Nam-Yerl;Lee, Chi-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.12
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    • pp.83-87
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    • 2015
  • This paper presents a simple notch filter, which is so suitable for three-phase unbalanced and distorted power line. In the d-q synchronous transformation, three-phase unbalanced and distorted voltages generate lots of ripple voltages on d-q axes. The ripples make disturbances on controllers such as PLL of phase tracking. Unbalanced state makes ripple of double the frequency of power line. Odd harmonics 5th and 7th on the line make even 4th and 6th ripples on d-q axes due to the rotating reference frame, respectively. Cascaded two comb filters, delay lines 1/4T and 1/8T, are adopted for the ripple rejection. The filter rejects harmonics 2nd, 4th, 6th, 10th and so on. They are very effective to remove the ripples of both unbalance and distortion. The filter, implemented by two FIFOs on an experimental system, is adopted on a PLL controller of power line phase tracking. Through the simulation and experimental results, performance of the proposed comb filter has been validated.

The performance improvement of new correlator architecture in vehicles navigation system (차량요 항법시스템 기반의 새로운 correlator 구조에 따른 성능 향상에 관한 연구)

  • Park, Chi-Ho;Oh, Young-Hwan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.12
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    • pp.44-53
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    • 2007
  • In this paper, we focus on the developments of complex location awareness algorithms for real-time location based service and precise/stable localization in the outdoor. In the case of using galileo satellite system along with GPS, several error factor such as the ionosphere can be reduced for an increment of used frequency and visible satellites. Therefore, localization estimation error is no longer having problems with location awareness. But, chips synchronization error induces the error of acquisition and tracking, and the performance of receiver can be decreased. In order to solve this problem, this paper proposes a correlator for performance improvement of receiver in the precise localization.

Tracking Control of 6-DOF Shaking Table with Bell Crank Structure (벨 크랭크 구조를 가지는 6 자유도 진동 시험기의 추적 제어)

  • Jeon, Duek-Jae;Park, Sung-Ho;Park, Young-Jin;Park, Youn-Sik;Kim, Hyoung-Eui
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.306-309
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    • 2005
  • This parer describes the tracking control simulation of 6-DOF shaking table with a bell crank structure, which converts the direction of reciprocating movements. For the Joint coordinate-based control which uses lengths of each actuator, the trajectory conversion process inverse kinematics is performed. Applying the Newton-Euler approach, the dynamic equation of the shaking table is derived. To cope with nonlinear problems, time-delay control(TDC) is considered, which has been noted for its exceptional robustness to parameter uncertainties and disturbance, in addition to steady-state accuracy and computational efficiency. If the nominal model is equal to the real system, joint coordinate-based control can be very efficient. However, manufacturing tolerances installation errors and link offsets contaminate the nominal values of the kinematic parameters used in the kinematic model of the shaking table. To compensate differences between the nominal model and the real system. the joint coordinate-based control using acceleration feedback in the Cartesian coordinate space is proposed.

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RCGA-Based Tuning of the 2DOF PID Controller (2자유도 PID 제어기의 RCGA기반 동조)

  • Hwang, Seung-Wook;Song, Se-Hoon;Kim, Jung-Keun;Lee, Yun-Hyung;Lee, Hyun-Shik;Jin, Gang-Gyoo
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.9
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    • pp.948-955
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    • 2008
  • The conventional PID controller has been widely employed in industry. However, the PID controller with one degree of freedom(DOF) can not optimize both set-point tracking response and disturbance rejection response at the same time. In order to solve this problem, a few types of 2DOF PID controllers have been suggested. In this paper, a tuning formula for a 2DOF PID controller is presented. The optimal parameter sets of the 2DOF PID controller are determined based on the first-order plus time delay process and a real-coded genetic algorithm(RCGA) such that the ITAE performance criterion is minimized. The tuning rule is then addressed using calculated parameter sets and another RCGA. A set of simulation works are carried out on three processes with time delay to verify the effectiveness of the proposed rule.

Fault-Tolerant Control System for Unmanned Aerial Vehicle Using Smart Actuators and Control Allocation (지능형 액추에이터와 제어면 재분배를 이용한 무인항공기 고장대처 제어시스템)

  • Yang, In-Seok;Kim, Ji-Yeon;Lee, Dong-Ik
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.10
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    • pp.967-982
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    • 2011
  • This paper presents a FTNCS (Fault-Tolerant Networked Control System) that can tolerate control surface failure and packet delay/loss in an UAV (Unmanned Aerial Vehicle). The proposed method utilizes the benefits of self-diagnosis by smart actuators along with the control allocation technique. A smart actuator is an intelligent actuation system combined with microprocessors to perform self-diagnosis and bi-directional communications. In the event of failure, the smart actuator provides the system supervisor with a set of actuator condition data. The system supervisor then compensate for the effect of faulty actuators by re-allocating redundant control surfaces based on the provided actuator condition data. In addition to the compensation of faulty actuators, the proposed FTNCS also includes an efficient algorithm to deal with network induced delay/packet loss. The proposed algorithm is based on a Lagrange polynomial interpolation method without any mathematical model of the system. Computer simulations with an UAV show that the proposed FTNCS can achieve a fast and accurate tracking performance even in the presence of actuator faults and network induced delays.

Cache Algorithm in Reverse Connection Setup Protocol(CRCP) for effective Location Management in PCS Network (PCS 네트워크 상에서 효율적인 위치관리를 위한 역방향 호설정 캐쉬 알고리즘(CRCP)에 관한 연구)

  • Ahn, Yun-Shok;An, Seok;Bae, Yun-Jeong;Jo, Jea-Jun;Kim, Jae-Ha;Kim, Byung-Gi
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.630-632
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    • 1998
  • The basic user location strategies proposed in current PCS(Personal Communication Services) Network are two-level Database strategies. These Databases which exist in the Signalling network always maintain user's current location information, and it is used in call setup process to a mobile user. As the number of PCS users are increasing, this strategies yield some problem such as concentrating signalling traffic on the Database, increasing Call setup Delay, and so on. In this paper, we proposed RCP(Reverse Connection setup Protocol) model, which apply RVC(Reverse Virtual Call setup) algorithm to PCS reference model, and CRCP(Cache algorithm in RCP) model, which adopt Caching strategies in the RCP model. When Cache-miss occur, we found that CRCP model require less miss-penalty than PCS model. Also we show that proposed models are always likely to yield better performance in terms of reduced Location Tracking Delay time.

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Performance Analysis on Clock Sychronization of CCK Modulation Scheme in Wireless LAN System (무선 LAN 시스템에서 CCK 변조방식의 클럭 동기 성능 분석)

  • 박정수;강희곡;조성언;조성준
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.583-586
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    • 2004
  • In this paper, we have analyzed the performance of synchronization of CCK(Complementary Code Keying) modulation scheme used for IEEE 802.11g wireless LAM system supporting 54 Mbps of high speed data rate over 2.4 GHz. At receiver, the clock frequency offset is caused by noise or fading. This frequency error occurs the offset of clock timing and causes ISI. Therefore the tracking is required to reduce the clock timing offset. The DLL(Delay Lock Loop), asychronization mode, performing tacking the clock is used for the simulation. The simulation result shows jitter variance and BER performance in the AWGN and multipath fading channel environment.

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A Hybrid Filtering Stage Based Quasi-type-1 PLL under Distorted Grid Conditions

  • Li, Yunlu;Wang, Dazhi;Han, Wei;Sun, Zhenao;Yuan, Tianqing
    • Journal of Power Electronics
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    • v.17 no.3
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    • pp.704-715
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    • 2017
  • For three-phase synchronization applications, the synchronous reference frame phase-locked loop (SRF-PLL) is probably the most widely used technique due to its ease of implementation and satisfactory phase tracking performance under ideal grid conditions. However, under unbalanced and distorted grid conditions, its performance tends to worsen. To deal with this problem, a variety of filtering stages have been proposed and used in SRF-PLLs for the rejection of disturbance components at the cost of degrading the dynamic performance. In this paper, to improve dynamic performance without compromising the filtering capability, an effective hybrid filtering stage is proposed and incorporated into the inner loop of a quasi-type-1 PLL (QT1-PLL). The proposed filtering stage is a combination of a moving average filter (MAF) and a modified delay signal cancellation (DSC) operator in cascade. The time delay caused by the proposed filtering stage is smaller than that in the conventional MAF-based and DSC-based PLLs. A small-signal model of the proposed PLL is derived. The stability is analyzed and parameters design guidelines are given. The effectiveness of the proposed PLL is confirmed through experimental results.

A Study on Response Time Delay and Tracking Error Suppression Strategy in Gear Mechanism : Control System Design Approach (기어 백래쉬로 인한 응답지연 및 추종오차 억제방안에 관한 연구)

  • Tran, Manh Son;Choi, Eun-Ho;KIM, Young-Bok
    • Journal of Power System Engineering
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    • v.21 no.4
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    • pp.77-83
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    • 2017
  • The aim of this paper is to solve the chattering and delayed response problems caused by gear backlash. In the gear mechanism based systems, for example, in robot systems, the actuators provide the reduction gear with motors to transfer effectively electric power to mechanical power. Therefore, the gear backlash exists and is an unavoidable fact which makes many undesirable problems. In this paper, the authors try to make a solution for this issue and, introduce several control methods which are PID only, PID with Smith predictor and super-twisting algorithm based SMC(sliding mode control). Each control method is applied to the real plant in which strong backlash is included. By comparison results, it is clear that SMC gives the best control performance with little backlash effects. Also, the usefulness and effectiveness of proposed control method is verified by experiment.