Multirate Sampling Control Research Articles

Multi-Rate Sampling Control Design and Stability Analysis for Frequency and Voltage Regulation in Islanded Microgrids

The wide use of inverters in microgrids motivates the development of digital controllers with sampling systems. This paper proposes a multi-rate sampling frequency and voltage regulation method for inverters-based distributed generators (DGs). The fast-sampling signals are adopted to achieve the primary control, which is composed of the VSG-based frequency control and the voltage droop control with a low-pass filter (LPF). Based on the unified primary control model, the low-sampling distributed model predictive control (DMPC) is proposed as secondary frequency and voltage control. Considering the microgrid network, the inverter-based DGs supply power for both the local load and loads on other buses. The proposed DMPC method can overcome the disproportionate impedances of interconnecting lines among buses. Then the frequency and voltage of islanded microgrid can be restored to rated values with accurate power sharing. The DMPC-based secondary control and the primary control have different sampling rates. The stability and dynamic performance of the proposed multi-rate sampling control system are investigated for the first time. Finally, both simulation and experiment tests are carried out to validate the effectiveness of the proposed control strategy.

Fundamental Issues and Prospective Directions in Networked Multirate Control Systems

In view of the synchronized uniform equidistant sampling method that is widely used in network control systems (NCSs), multirate sampling control for NCSs is presented by considering the natural characteristics of NCSs. Two kinds of typical structures of network multirate control systems (NMCSs) are presented and the multirate sampling mechanisms are formulated. Then, fundamental issues and prospective directions in NMCSs are preliminarily discussed. The contents involve modeling, sampling pattern selection, control strategies, scheduling algorithms, and codesign of NMCSs. The purpose of this paper is to arouse more attention of researchers in related subjects, so that a complete theory for NCSs can be established.

1A1-L04 構造可変型ロボットに対するマルチレートサンプリング制御(動作計画と制御の新展開)

The conventional demand on robots in industrial fields has been oriented mainly to mass production, but the demand nowadays is diverse to meet the trend toward high-variation and low-quantity production. To meet this demand, we have proposed a reconfigurable robot which can change a robot configuration easily. In this paper, we construct the multirate sampling control for a reconfigurable robot. Firstly, we describe the concept of a reconfigurable robot. Secondly, the decentralized control in the system consisting of local and central intelligence is explained. Thirdly, the advantage of the multirate sampling is explained. Lastly, the effectiveness of the proposed system is confirmed by several experimental results.

Hybrid Output Feedback Stabilization for LTI Systems With Single Output

This note presents a hybrid control scheme for a class of continuous-time LTI systems that cannot be stabilized by a single static output feedback (SOF) controller. The main idea here is to design multiple SOF gains and proper logic rules that orchestrate switching among these gains so as to achieve the global stability. One challenge, however, is that the switching logic should be in the output feedback form as well. This may seriously restrict the possible choices of switching surfaces, especially when the output is just a scalar. To overcome this difficulty, a multirate sampling control scheme is proposed. Under this framework, a hybrid output feedback stabilizing controller is designed, and sufficient controller synthesis conditions are proposed as linear matrix inequalities based on multiple Lyapunov function theorems. The note concludes with a discussion on possible extensions and future research topics.

Short‐span seeking control of hard disk drive with vibration suppression PTC

AbstractIn a short‐span seeking‐mode of hard disk drives, the resonance modes are getting crucial obstruction to meet the demand on high‐speed data access. In this paper, a novel vibration suppression perfect tracking control (PTC) method is proposed based on controllable canonical realization. In the proposed method, it is assumed that the plant is modeled as the rigid and primary resonance mode. By using this model, the feed forward controller is designed with PTC by multirate sampling control in order to suppress the primary vibration. Additionally, the higher‐order resonance vibration is attenuated by using the trajectory MHVT. The proposed method achieved 16% faster seeking than MPVT, a conventional method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 66–72, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20546

制振PTCによる磁気ディスク装置のショートスパンシーク制御

In a short-span seeking-mode of hard disk drives, the resonance modes are getting crucial obstruction to meet the demand on high-speed data access. In this paper, a novel vibration suppression perfect tracking control (PTC) method is proposed based on controllable canonical realization. In the proposed method, it is assumed that the plant is modeled as the rigid and primary resonance mode. By using this model, the feed forward controller is designed with PTC by multirate sampling control in order to suppress the primary vibration. Additionally, the higher-order resonance vibration is attenuated by using the trajectory MHVT. The proposed method achieved 16% faster seeking than MPVT, a conventional method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 66–72, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20546

High-performance servo systems based on multirate sampling control

In this paper, novel multirate two-degree-of-freedom controllers are proposed for digital control systems, in which the sampling period of plant output is restricted to be relatively longer than the control period of plant input. The proposed feedforward controller assures perfect tracking at M inter-sampling points. On the other hand, the proposed feedback controller assures perfect disturbance rejection at M inter-sample points in the steady state. Illustrative examples of position control for hard disk drive are presented, and the advantages of these approaches are demonstrated. r 2002 Elsevier Science Ltd. All rights reserved.

ADVANCED DIGITAL MOTION CONTROL BASED ON MULTIRATE SAMPLING CONTROL

In this paper, our recent studies on multirate sampling control and its application to motion control systems are reviewed. Especially, multirate two-degree-of-freedom controllers are focused on, where it is restricted that the sampling period of plant output is longer than the control period. The proposed controllers assure perfect tracking control (PTC) and perfect disturbance rejection (PDR) at M inter-sampling points. The proposed approaches are applied to the position control of servomotors, hard disk drives, and visual servo systems. The advantages are demonstrated through simulations and experiments.

Seeking Control of Hard Disk Drive by Perfect Tracking Using Multirate Sampling Control

In this paper, novel multirate two-degree-of-freedom 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 feedforward controller assures the perfect tracking at M inter-sampling points. Next, the proposed method is extended to systems with time delay. The proposed scheme is applied to the seeking control for hard disk drive, and advantages of this approach are demonstrated.

High performance perfect tracking control based on multirate feedforward / feedback controllers with generalized sampling periods

In this paper, a novel perfect tracking control method based on the multirate sampling control is proposed, in which the concepts of the two-degree-of-freedom control are employed. Moreover, by generalizing the multirate input and output sampling periods, the proposed method can match the restrictions of the sampling periods caused by the hardware, and achieve higher performance. The main results of this paper are 1) the perfect tracking performance is assured in the in the intersampling points, if the input multiplicity is increased, 2) higher feedback performance is achieved, if the output multiplicity is increased. Illustrative examples of position control using a dc servo motor are presented, and simulations and experiments demonstrate the advantages of this approach.

Digital control in iron- and steelmaking processes

There are two kinds of processes involved in steelmaking. One is well defined by a mathematical model, the other cannot be defined because of parameter uncertainty, nonlinearity and large dead time. In this paper, model-based controls such as optimal control and observer based control are shown to be useful in rolling mills and roll speed control systems. This paper presents a new digital control system called “Holon-type hybrid control”, a model-free control which is a useful method for controlling heat processes, for example. Such plants are well known to possess time-varying parameter properties (nonlinear processes) and large dead time. The model-free control system, which is a hierarchical and multirate sampling control method, is confirmed to be effective in a complicated heat plant with parameter uncertainty and time delay by applying the control system to our Organic Rankin Cycle System heat recovery plant experiment in the steelmaking process.