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

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     

Two-degrees-of-freedom speed control of resonant mechanical system based on H∞ control theory

In industrial motor drive systems such as those used in industrial plants and robots, a torsional vibration is often generated as a result of the elastic elements present in the torque transmission systems. This vibration makes it difficult to achieve quick speed responses and may result in plant damage. Such systems are simply modeled as two-mass mechanical systems. The H^∞ control theory is applied herein to design a speed controller for the two-mass system. This controller determines closed-loop characteristics, including suppression of torsional vibration, rejection of torque disturbance and robust stability. Moreover, two types of two-degrees-of-freedom control systems, which includes the H^∞ controller, are proposed to improve command response. One is based on the TDOF PI control, in which the PI controller included in the H^∞ controller is rearranged for the TDOF system. Another is based on the model matching feedforward control, in which the prefilter and the feedforward compensator are added to the H^∞ controller. The proposed control system is applied to two types of resonant mechanical systems having different inertia ratio. Several examinations demonstrate that the proposed speed control system is useful for a resonant mechanical system.     

Vibration control for pneumatic isolation table with feedforward control input

In this paper, we consider a vibration suppression problem for a pneumatic isolation table with on–off valves using the feedforward control input profile. In this system, it is possible to enhance the vibration suppression performance by adjusting the flow rate of air into and from air springs. However, there is a significant problem that a steady‐state deviation, namely an offset, for displacement of the table occurs. Therefore, we propose an efficient search method of the optimal feedforward control input profile, which provides high vibration suppression performance without a steady‐state deviation. A key idea is to update the control input profile to belong to a space where velocity of the table does not change.     

仿人灵巧手关节的位置/力矩控制

为了使仿人灵巧手完成各种精细作业,提出了一种新的关节位置／力矩控制方法。在自由空间和约束空间中分别采用滑模位置控制和具有前馈的PD力矩控制,在过渡过程中使用系统观测器切换控制模式。这种方法可以使关节在自由空间和约束空间中分别实现良好的轨迹跟踪和力矩跟踪,在过渡过程中实现控制模式的可靠切换和系统的稳定过渡。实验证明了该方法的有效性。     

Suppression control method for torque vibration of AC motor utilizing repetitive controller with Fourier transform

In this paper, the authors propose a method to obtain the compensation signal to suppress the vibration of the. motor frame by the repetitive control installing an online Fourier transform and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor (microphone) detected by a microphone placed close to the motor frame. The sensor is used only for the acquisition of the feedforward compensation data. Also presented is a new method of the feedforward compensation control adapting to change of operating point of the motor. The effectiveness of the proposed method is confirmed by experimental results.     

Active vibration control of a motor system by using H∞ control theory

This paper considers the vibration control of a motor system which has a motor and a load connected with a flexible shaft. However, this system often generates a shaft torsional vibration. Traditional methods of treating this problem to adjust the PID controller so that the closed-loop frequency response is slower than that of the vibration mode. On the other hand, one method has already been proposed in which the vibration is suppressed by a disturbance observer. This paper proposes a new approach based on H_∞ control theory. For comparison, a PI control system based on classical control theory also is constructed. The results of several experiments show that compared with the PI control system, the H_∞ control system is effective in suppressing the vibration. Further, the H_∞ controller obtained in the study consists of a PI controller and a series compensator that functions as an active vibration controller.     

Suppression control of speed variation in an induction motor with fluctuating load by repetitive learning control

Induction motors are robust and inexpensive machines and are used widely for variable speed control because of the recent development of electronic technique. In the case where loads of the motors are compressors, pumps, and so on, the constant V/F control of the induction motors usually is employed because it is difficult to install speed sensors and accurate speed control is not required. In such loads, the rotational speed of the motors fluctuates considerably because the load torque is pulsated. When the frequency of the torque pulsation is close to the resonant frequency of the mechanical system, large vibration and acoustic noise are produced especially in the low-frequency region. This paper proposes a method to suppress the variation of the rotational speed of the V/F controlled induction motor with a fluctuated load by feedforward compensation using a timing sensor of 1 pulse/rev, considering that the load torque varies periodically. The feedforward data by a period for the compensation is obtained by the learning control based on the repetitive control in which the motor speed is controlled by periodically reflecting the past speed error on the present V/F input to the inverter. Effectiveness of the proposed method is confirmed by approximate analysis, simulations and experiments.     

Tracking control for industrial robot using notch filtering system with little phase error

This paper proposes a new method for generation of a position reference that has both vibration suppression performance and fast tracking performance for industrial robots. It is important for industrial robots to drive at high speed and with high accuracy. In such cases, vibration is generated. Conventionally, the notch filter is used in order to reduce vibration. It is able to eliminate the natural frequency component, but a reference phase error is generated. The reference phase error causes locus error in the robot. Therefore, the accuracy of the robot is degraded by using a notch filter. The proposed method overcomes this problem by using the compensation gain. The proposed compensation gain is used in order to calculate the reference phase error. Compensation of the reference phase error is attained by feedforward input. Numerical and the experimental results confirm that the proposed method is valid for reducing vibration phenomena and that it decreases the phase error. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 53–63, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.20931     

A design method of a generalized predictive control system based on parametrization of two‐degree‐of‐freedom integral controllers

A new design method for a generalized predictive control (GPC) system based on parametrization of two‐degree‐of‐freedom integral controllers has been proposed. The objective is to guarantee stability of the control system without depending on the design parameters and to achieve low sensitivity against the plant perturbation and the disturbance. The design procedure consists of two steps. First, we design a basic integral controller for a nominal plant using the linear quadratic Gaussian (LQG) method and parametrize a class of two‐degree‐of‐freedom stabilizing controllers. Next, we tune the feedforward controller to incorporate the GPC method into our control structure. A numerical example is presented to show the effectiveness of the proposed method by comparing it with the conventional GPC method. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 62–70, 1999     

基于扩张状态观测器的DFIG网侧变换器滑模控制

针对双馈风力发电机网侧变换器因负载变化和滤波参数摄动导致控制效果不佳的问题,提出一种扩张状态观测器（extended state observer, ESO）与滑模控制相结合的网侧变换器双闭环控制策略。内环采用以功率为状态变量的基于ESO的滑模直接功率控制,外环采用以电压平方为状态变量的基于ESO的滑模控制;应用ESO对系统状态变量与包含系统未建模动态、负载变化和滤波参数摄动等集总不确定项进行估计,即可无需系统的精确数学模型设计滑模控制方法,实现网侧变换器在复杂环境下的鲁棒控制,理论分析了ESO和滑模控制的稳定性。此外引入功率差前馈环节,减小负载变化时外环滑模控制非线性带来的冲击。最后通过负载变化和滤波参数摄动两个算例仿真,结果表明,与传统矢量控制和滑模控制相比,所提控制策略在复杂环境下具有更强的鲁棒性。     

基于超螺旋滑模观测器的永磁同步直线电机无模型控制

针对永磁同步直线电机(permanent magnet linear synchronous motor, PMLSM)在运行过程中因参数失配和外部扰动导致控制性能下降的问题,提出一种基于超螺旋滑模观测器的永磁同步直线电机无模型控制策略。根据PMLSM在dq旋转坐标系下参数摄动时的数学模型建立电机对应的新型超局部模型,以避免参数失配。基于该新型超局部模型,结合滑模控制设计了无模型滑模速度控制器,通过Lyapunov稳定性理论证明该控制器的稳定性。同时,为削弱传统扩展滑模观测器对新型超局部模型中未知量观测的抖振,提高控制精度,设计超螺旋滑模观测器(super-twisting sliding mode observer, STSMO)对未知量进行在线辨识并实现前馈补偿。最后,将传统滑模控制、基于传统扩展滑模观测器的无模型控制算法与所提方法进行仿真和硬件在环实验对比,结果表明所提方法改善了PMLSM控制系统的动态响应性能,具有较强的鲁棒性。     

Position command shaping for vibration suppression considering target position correction

This paper presents a command shaping technique based on a minimum jerk control approach that takes into consideration target position correction during motion, for the fast and precise positioning in vibratory mechatronic systems. The positioning controller is designed using a two‐degree‐of‐freedom control: a feedback compensator is synthesized by H_∞ control design to ensure the robust stability, while a feedforward compensator suppresses the vibration in response based on a coprime factorization expression of the plant mechanism. The command shaping, on the other hand, eliminates the corresponding vibration components of the primary and secondary models in the position command, where the continuity of jerk component in the command can be ensured against the target position correction. The effectiveness of the proposed shaping technique has been verified by experiments using a table drive system on a machine stand. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 38–47, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20838     

Cylinder pressure sensor‐based real‐time combustion phase control approach for SI engines

As one of most effective factors affecting the economy and emissions of internal combustion engines, the combustion phase can maximize performance by tracking its optimum reference. In this study, the combustion phase indicator CA50 is employed for the combustion control of spark‐ignited (SI) engines with the application of a cylinder pressure sensor. In order to suppress the influence of cylinder pressure variation on CA50 measurement, a moving average method is used to stabilize CA50 calculation, and based on measured CA50, a linear autoregressive model is obtained by identification, which depicts the relationship between spark advance and combustion phase. Then, a closed‐loop controller is synthesized for CA50 regulation, including both feedforward and feedback channels. Finally, the proposed strategy is validated by experiments on an SI engine. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Robust and simple adaptive control system design

Recently, the simple adaptive control (SAC) method has attracted considerable interest because of the simple structure of its adaptive controller. The method can only be applied to plants with so-called almost strictly positive real (ASPR) characteristics. Unfortunately, most real plants do not satisfy this condition. Furthermore, real plants contain disturbances such as uncertain elements. This paper deals with such problems and proves that the implementation of a parallel feedforward compensator makes it possible to apply the SAC method to non-ASPR SISO plants with plant uncertainties. Furthermore, a robust SAC algorithm in the presence of a class of external disturbances is also considered. The effectiveness of the parallel feedforward compensator and robust adaptive controller designed in this way is examined through several numerical simulations.     

基于 GMS 摩擦力补偿和干扰观测器的高精度速度控制

为了降低机械轴系摩擦力扰动对于伺服控制器在低速运动控制精度的影响,进一步提高传统伺服控制器对于稳定平 台的控制能力,提出了一种基于广义 Maxwell 滑动(generalized Maxwell-slip,GMS) 摩擦力模型前馈和干扰观测器的高精度 摩擦力补偿方案。首先在传统控制基础上引入GMS 摩擦模型前馈补偿对摩擦扰动进行初步的补偿;然后,通过加入干扰观 测器,对残余扰动及其他扰动进行第2次的抑制。利用实物平台对控制方法的低速运动性能进行了测试,对比设计的控制算 法和传统 PI 控制器的控制结果,验证提出的控制策略抑制摩擦扰动的效果。结果表明,基于 GMS 摩擦力前馈和干扰观测器 的控制方案有效的补偿了摩擦非线性、模型不确定性等因素对于控制系统的影响。新方法可将稳定平台低速运动时的控制 误差降低到0.015°/s, 在实际工程中具有较高的应用价值。     

Realization of anti-slip/skid re-adhesion control for electric commuter train based on disturbance observer

Recently, disturbance observer has been used in many system and industry applications. This paper focus on the fine motion control technology based on disturbance observer for electric commuter train. The improvement of adhesion characteristics is important in electric commuter train. We propose the anti-slip/skid re-adhesion control system based on disturbance observer and sensor-less vector control. The effectiveness of the proposed method is confirmed by the experiment based on the actual electric commuter train, which is Series 205-5000 of East Japan Railway Company. Moreover, in order to extend the anti-slip/skid re-adhesion control considering the bogie vibration phenomenon, we propose a new anti-slip re-adhesion control based on the high order disturbance observer considering the resonant frequency of bogie system. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Low‐latency retransmission control in a wireless communication system for plant instrumentation and control

When wireless communication technology is applied to plant instrumentation and control systems, it is important to ensure real‐time transmission and high reliability of the wireless communication system. However, the wireless communication system is prone to more frequent occurrence of transmission errors than a wired communication system, so that generally retransmission is implemented generically. To reduce retransmission latency, we propose a method of low‐latency retransmission control, which is a data block transmission method with multi‐redundant media access control layer (MAC) headers, to implement a wireless communication system for plant instrumentation and control. We carried out system tests using prototypes with the proposed methods, that is, data block transmission with multi‐redundant MAC headers. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Actuator fault‐tolerant control based on set separation

In this paper, an actuator fault‐tolerant control (FTC) strategy based on set separation is presented. The proposed scheme employs a standard configuration consisting of a bank of observers which match the different fault situations that can occur in the plant. Each of these observers has an associated estimation error with a distinctive behaviour when a estimator matches the current fault situation of the plant. With this information from each observer, a fault diagnosis and isolation (FDI) module is able to reconfigure the control loop by selecting the appropriate stabilising controller from a bank of precomputed control laws, each of them related to one of the considered fault models. The control law consists of a reference feedforward term and a feedback gain multiplying the state estimate provided by the matching observer. A novel feature of the proposed scheme resides in the decision criteria of the FDI, which is based on the computation of sets towards which the output estimation errors related to each fault scenario and for each control configuration converge. Conditions for the design of the FDI module and for fault tolerant closed‐loop stability are given, and the effectiveness of the approach is illustrated by means of a numerical example. Copyright © 2010 John Wiley & Sons, Ltd.     

Modeling and design of networked control systems using a stochastic switching systems approach

A networked control system (NCS) is a control system in which plants, sensors, controllers, and actuators are connected through communication networks. In this paper, we consider NCSs modeled by stochastic switching systems, and propose a new method for modeling and optimal control. First, a recursive representation of the expected value of the state is proposed. Next, after an over‐approximation of this recursive representation is derived, the optimal control problem is reduced to a linear programming problem. Finally, the effectiveness of the proposed method is shown by a numerical example. The proposed method provides us an easy‐to‐use control method for NCSs. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Speed control system and design of resonant system with disturbance observer

In industrial motor drive systems such as industrial plants and industrial robots, a torsional vibration often is generated because of the elastic elements in torque transmission. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the plant. Such systems simply are modeled as a two mass system. The shaft torque feedback system with the disturbance observer, which is called “resonance ratio control,” is proposed to suppress the vibration for the two-mass system. In this paper, the design of controller gains in the shaft torque feedback system is examined considering not only the control performance such as the vibration suppression and dynamic responses, but also the robust stability against the noise and the model uncertainties. This paper shows the validity of the control system and the examinations by several experiments.