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Chee Khiang Pang - One of the best experts on this subject based on the ideXlab platform.

  • Periodic disturbance rejection to the Nyquist Frequency and beyond
    Control Engineering Practice, 2018
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Abstract In this paper, we address periodic disturbance rejection for sampled-data control systems, where the Frequency of the disturbance can be beyond the Nyquist Frequency of the limited measured plant output sampling rate. The disturbance effect on steady-state response of the fictitious fast-rate plant output including intersample information is obtained using discrete-time Fourier series. A sufficient condition for disturbance rejection together with a sufficient and necessary condition for perfect disturbance elimination are provided by employing the steady-state response. A simple but effective controller design procedure combining H ∞ loop shaping, Youla–Kucera parameterization, and gradient methods is provided to achieve the two conditions. The proposed approach is applied on vibration control beyond the Nyquist Frequency in a commercial hard disk drive. The effectiveness of the proposed approach is verified by our simulation results showing disturbance rejection of  62 % and perfect disturbance elimination, as well as by our experimental results showing disturbance rejection of  54 % .

  • Disturbance observer-based multirate control for rejecting periodic disturbances to the Nyquist Frequency and beyond
    Automatica, 2017
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Abstract Intersample behavior cannot be ignored when a sampled-data control system is subject to periodic disturbances beyond the Nyquist Frequency. In this paper, a disturbance observer-based multirate control scheme is proposed to deal with such a periodic disturbance problem. First, using discrete-time Fourier series, the effect of the periodic disturbance on steady-state response of the plant output including intersample information is derived. Next, based on the steady-state output response, a sufficient condition is provided for minimization of the disturbance effect on the output. It turns out that solving the sufficient condition is a problem of quadratic optimization with several equality constraints. The proposed approach is applied on vibration control of mechanical resonant modes beyond the Nyquist Frequency in a commercial hard disk drive. Perfect disturbance elimination and disturbance deduction of 72% in fast-rate discrete-time response are observed in the simulation and experiment, respectively.

  • disturbance observer based multirate control for rejecting periodic disturbances beyond the Nyquist Frequency
    International Workshop on Advanced Motion Control, 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Periodic disturbances existing beyond the Nyquist Frequency will cause intersample oscillations and degrade the control performance. In this paper, we propose a disturbance observer-based multirate control scheme for rejecting such periodic disturbances. When the disturbance is a single sinusoid, the solution for system output including the intersample information is derived in the steady state. Based on the steady-state output response, a sufficient condition is given for rejecting periodic disturbance beyond the Nyquist Frequency. As a matter of fact, solving the sufficient condition is a problem of quadratic programming with some constraints. To remove the constraints, a periodic time-varying filter is also suggested to enhance the disturbance rejection performance. A numerical example is presented to demonstrate the effectiveness of the proposed method.

  • AMC - Disturbance observer-based multirate control for rejecting periodic disturbances beyond the Nyquist Frequency
    2016 IEEE 14th International Workshop on Advanced Motion Control (AMC), 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Periodic disturbances existing beyond the Nyquist Frequency will cause intersample oscillations and degrade the control performance. In this paper, we propose a disturbance observer-based multirate control scheme for rejecting such periodic disturbances. When the disturbance is a single sinusoid, the solution for system output including the intersample information is derived in the steady state. Based on the steady-state output response, a sufficient condition is given for rejecting periodic disturbance beyond the Nyquist Frequency. As a matter of fact, solving the sufficient condition is a problem of quadratic programming with some constraints. To remove the constraints, a periodic time-varying filter is also suggested to enhance the disturbance rejection performance. A numerical example is presented to demonstrate the effectiveness of the proposed method.

  • Multirate adaptive control of uncertain resonances beyond the Nyquist Frequency in high-performance mechatronic systems
    Automatica, 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    In this paper, an add-on multirate adaptive control scheme is proposed to compensate for uncertain mechanical resonant modes beyond the Nyquist Frequency in mechatronic systems. The multirate adaptive controller is incorporated into the existing sampled-data control system sampled at a slow rate. To integrate well with the pre-designed feedback controller, an auxiliary error instead of the regulation error is utilized to design the multirate adaptive controller. By using a polynomial transformation technique and a recursive least-squares algorithm with a dead-zone, the proposed multirate adaptive control ensures boundedness of all the closed-loop signals and convergence of the auxiliary error. Our simulation and experimental results on the head-positioning servo control system of a hard disk drive demonstrate the effectiveness of our proposed compensation scheme in attenuating the vibration for uncertain resonances beyond the Nyquist Frequency.

Seiichi Gohshi - One of the best experts on this subject based on the ideXlab platform.

  • 42.2L: Late‐News Paper: Real‐Time Up‐Converter from HDTV to 4K with Super Resolution ‐Breaking the Nyquist Frequency Barrier‐
    SID Symposium Digest of Technical Papers, 2013
    Co-Authors: Seiichi Gohshi, Shinichiro Nakamura, Jin Ogasawara
    Abstract:

    This real-time up-converter from HDTV to 4K with a novel Super Resolution (SR) is proposed in this paper. It creates 4K video with Frequency elements higher than the Nyquist Frequency of the original HDTV video. The novel SR uses non-linear signal processing to overcome the theoretical limitation of the Nyquist Frequency.

  • Real‐time up‐converter from HDTV to 4K with super‐resolution: Breaking the Nyquist Frequency barrier
    Journal of the Society for Information Display, 2013
    Co-Authors: Seiichi Gohshi, Shinichiro Nakamura, Jin Ogasawara
    Abstract:

    This real-time up-converter from HDTV to 4K with a novel Super Resolution (SR) is proposed in this paper. It creates 4K video with Frequency elements higher than the Nyquist Frequency of the original HDTV video. The novel SR uses non-linear signal processing to overcome the theoretical limitation of the Nyquist Frequency.

  • A New Signal Processing Method for Video Image-Reproduce the Frequency Spectrum Exceeding the Nyquist Frequency Using a Single Frame of the Video Image
    The Era of Interactive Media, 2012
    Co-Authors: Seiichi Gohshi
    Abstract:

    A new non-linear signal processing method is proposed in this paper. Enhancers are widely used in real time signal processing machines to improve the image quality. It does not actually increase the resolution but improves the degree of resolution as perceived by the human eye. It is almost impossible to create components exceeding the Nyquist Frequency using conventional linear signal processing methods. Super Resolution (SR) is a highly interesting research field and many ideas and methods have been proposed and some of which have the potential to enhance resolution. However, most of these ideas use several frames of video images and they have not been widely discussed in the Frequency domain. The new signal processing method in this paper uses just a single frame of the video image and creates components exceeding the Nyquist Frequency. The simu- lation results are discussed with regard to the picture quality well as the Frequency domain.

  • a new signal processing method for video reproduce the Frequency spectrum exceeding the Nyquist Frequency
    Proceedings of the 3rd Multimedia Systems Conference on, 2012
    Co-Authors: Seiichi Gohshi
    Abstract:

    A new signal processing method to improve video image quality is proposed in this paper. Improving video image resolution has been researched for many years. The method of edge enhancing is usually known as Sharpness Circuit (SC), Enhancer or Unsharp Mask,. It is widely used since it works in real time and it is cost efficient. However, edge enhancing does not actually improve the degree of resolution but increases perceived resolution. It is almost impossible to create components exceeding the Nyquist Frequency using conventional linear signal processing methods. Super Resolution (SR) is a highly interesting research field and many ideas and methods have been proposed, some of which have the potential to actually enhance the resolution. However, these ideas have not been widely discussed in the Frequency domain. A new signal processing method that creates components exceeding the Nyquist Frequency is proposed. The simulation results are discussed with regard to time domain as well as to the Frequency domain.

  • MMSys - A new signal processing method for video: reproduce the Frequency spectrum exceeding the Nyquist Frequency
    Proceedings of the 3rd Multimedia Systems Conference on - MMSys '12, 2012
    Co-Authors: Seiichi Gohshi
    Abstract:

    A new signal processing method to improve video image quality is proposed in this paper. Improving video image resolution has been researched for many years. The method of edge enhancing is usually known as Sharpness Circuit (SC), Enhancer or Unsharp Mask,. It is widely used since it works in real time and it is cost efficient. However, edge enhancing does not actually improve the degree of resolution but increases perceived resolution. It is almost impossible to create components exceeding the Nyquist Frequency using conventional linear signal processing methods. Super Resolution (SR) is a highly interesting research field and many ideas and methods have been proposed, some of which have the potential to actually enhance the resolution. However, these ideas have not been widely discussed in the Frequency domain. A new signal processing method that creates components exceeding the Nyquist Frequency is proposed. The simulation results are discussed with regard to time domain as well as to the Frequency domain.

Yoichi Hori - One of the best experts on this subject based on the ideXlab platform.

  • Vibration suppression and optimal repetitive disturbance rejection control in semi-Nyquist Frequency region using multirate sampling control
    Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187), 2000
    Co-Authors: Hiroshi Fujimoto, Yoichi Hori
    Abstract:

    Multirate feedback controllers are proposed for digital control systems with relatively long sampling period. The proposed controllers achieve vibration suppression and disturbance rejection even in the semi-Nyquist Frequency region. First, the continuous-time vibration suppression controller is exactly discretized by the multirate sampling control based on the closed-loop characteristics. Second, multirate repetitive controllers are proposed both by the feedback and feedforward approaches. Moreover, the inter-sample disturbance rejection performance is optimized by the fast sampling approach. The proposed controllers are applied to the settling and following modes of hard disk drive, and the advantages of these approaches are demonstrated by simulations

  • vibration suppression and disturbance rejection control in semi Nyquist Frequency region based on a novel multirate sampling control with initial value compensation
    2000
    Co-Authors: Hiroshi Fujimoto, Yoichi Hori, Slovak Republic
    Abstract:

    In this paper, novel multirate feedback controllers are proposed for digital control systems, where it is restricted that the speed of the A/D converters are slower than that of the D/A converters. The proposed controllers achieve vibration suppression and disturbance rejection even in the semi- Nyquist Frequency region. First, the continuous-time vibration suppression controller is exactly discretized by the multirate sampling control based on the closed-loop characteristics. Second, the multirate repetitive controllers are proposed both by the feedback and feedforward approaches. Moreover, the initial value compensations for observer are proposed in order to prevent the overshoot. The proposed controllers are applied to the settling and following modes of hard disk drive, and the advantages of these approaches are demonstrated by simulations.

Weili Yan - One of the best experts on this subject based on the ideXlab platform.

  • Periodic disturbance rejection to the Nyquist Frequency and beyond
    Control Engineering Practice, 2018
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Abstract In this paper, we address periodic disturbance rejection for sampled-data control systems, where the Frequency of the disturbance can be beyond the Nyquist Frequency of the limited measured plant output sampling rate. The disturbance effect on steady-state response of the fictitious fast-rate plant output including intersample information is obtained using discrete-time Fourier series. A sufficient condition for disturbance rejection together with a sufficient and necessary condition for perfect disturbance elimination are provided by employing the steady-state response. A simple but effective controller design procedure combining H ∞ loop shaping, Youla–Kucera parameterization, and gradient methods is provided to achieve the two conditions. The proposed approach is applied on vibration control beyond the Nyquist Frequency in a commercial hard disk drive. The effectiveness of the proposed approach is verified by our simulation results showing disturbance rejection of  62 % and perfect disturbance elimination, as well as by our experimental results showing disturbance rejection of  54 % .

  • Disturbance observer-based multirate control for rejecting periodic disturbances to the Nyquist Frequency and beyond
    Automatica, 2017
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Abstract Intersample behavior cannot be ignored when a sampled-data control system is subject to periodic disturbances beyond the Nyquist Frequency. In this paper, a disturbance observer-based multirate control scheme is proposed to deal with such a periodic disturbance problem. First, using discrete-time Fourier series, the effect of the periodic disturbance on steady-state response of the plant output including intersample information is derived. Next, based on the steady-state output response, a sufficient condition is provided for minimization of the disturbance effect on the output. It turns out that solving the sufficient condition is a problem of quadratic optimization with several equality constraints. The proposed approach is applied on vibration control of mechanical resonant modes beyond the Nyquist Frequency in a commercial hard disk drive. Perfect disturbance elimination and disturbance deduction of 72% in fast-rate discrete-time response are observed in the simulation and experiment, respectively.

  • disturbance observer based multirate control for rejecting periodic disturbances beyond the Nyquist Frequency
    International Workshop on Advanced Motion Control, 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Periodic disturbances existing beyond the Nyquist Frequency will cause intersample oscillations and degrade the control performance. In this paper, we propose a disturbance observer-based multirate control scheme for rejecting such periodic disturbances. When the disturbance is a single sinusoid, the solution for system output including the intersample information is derived in the steady state. Based on the steady-state output response, a sufficient condition is given for rejecting periodic disturbance beyond the Nyquist Frequency. As a matter of fact, solving the sufficient condition is a problem of quadratic programming with some constraints. To remove the constraints, a periodic time-varying filter is also suggested to enhance the disturbance rejection performance. A numerical example is presented to demonstrate the effectiveness of the proposed method.

  • AMC - Disturbance observer-based multirate control for rejecting periodic disturbances beyond the Nyquist Frequency
    2016 IEEE 14th International Workshop on Advanced Motion Control (AMC), 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    Periodic disturbances existing beyond the Nyquist Frequency will cause intersample oscillations and degrade the control performance. In this paper, we propose a disturbance observer-based multirate control scheme for rejecting such periodic disturbances. When the disturbance is a single sinusoid, the solution for system output including the intersample information is derived in the steady state. Based on the steady-state output response, a sufficient condition is given for rejecting periodic disturbance beyond the Nyquist Frequency. As a matter of fact, solving the sufficient condition is a problem of quadratic programming with some constraints. To remove the constraints, a periodic time-varying filter is also suggested to enhance the disturbance rejection performance. A numerical example is presented to demonstrate the effectiveness of the proposed method.

  • Multirate adaptive control of uncertain resonances beyond the Nyquist Frequency in high-performance mechatronic systems
    Automatica, 2016
    Co-Authors: Weili Yan, Chee Khiang Pang
    Abstract:

    In this paper, an add-on multirate adaptive control scheme is proposed to compensate for uncertain mechanical resonant modes beyond the Nyquist Frequency in mechatronic systems. The multirate adaptive controller is incorporated into the existing sampled-data control system sampled at a slow rate. To integrate well with the pre-designed feedback controller, an auxiliary error instead of the regulation error is utilized to design the multirate adaptive controller. By using a polynomial transformation technique and a recursive least-squares algorithm with a dead-zone, the proposed multirate adaptive control ensures boundedness of all the closed-loop signals and convergence of the auxiliary error. Our simulation and experimental results on the head-positioning servo control system of a hard disk drive demonstrate the effectiveness of our proposed compensation scheme in attenuating the vibration for uncertain resonances beyond the Nyquist Frequency.

Hiroshi Fujimoto - One of the best experts on this subject based on the ideXlab platform.

  • Vibration suppression and optimal repetitive disturbance rejection control in semi-Nyquist Frequency region using multirate sampling control
    Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187), 2000
    Co-Authors: Hiroshi Fujimoto, Yoichi Hori
    Abstract:

    Multirate feedback controllers are proposed for digital control systems with relatively long sampling period. The proposed controllers achieve vibration suppression and disturbance rejection even in the semi-Nyquist Frequency region. First, the continuous-time vibration suppression controller is exactly discretized by the multirate sampling control based on the closed-loop characteristics. Second, multirate repetitive controllers are proposed both by the feedback and feedforward approaches. Moreover, the inter-sample disturbance rejection performance is optimized by the fast sampling approach. The proposed controllers are applied to the settling and following modes of hard disk drive, and the advantages of these approaches are demonstrated by simulations

  • vibration suppression and disturbance rejection control in semi Nyquist Frequency region based on a novel multirate sampling control with initial value compensation
    2000
    Co-Authors: Hiroshi Fujimoto, Yoichi Hori, Slovak Republic
    Abstract:

    In this paper, novel multirate feedback controllers are proposed for digital control systems, where it is restricted that the speed of the A/D converters are slower than that of the D/A converters. The proposed controllers achieve vibration suppression and disturbance rejection even in the semi- Nyquist Frequency region. First, the continuous-time vibration suppression controller is exactly discretized by the multirate sampling control based on the closed-loop characteristics. Second, the multirate repetitive controllers are proposed both by the feedback and feedforward approaches. Moreover, the initial value compensations for observer are proposed in order to prevent the overshoot. The proposed controllers are applied to the settling and following modes of hard disk drive, and the advantages of these approaches are demonstrated by simulations.