Robust feedforward control system considering sudden disturbance for optical disk recording system

This paper proposes a new robust feedforward tracking servo system for optical disk recording systems in the case of a sudden disturbance for the optical disk recording system. In optical recording systems, the tracking servo system must suppress tracking error below its tolerance. This paper designs the robust feedback control system by using the coprime factorization and disturbance observer. The proposed robust feedback control system suppresses the sudden disturbance caused by walking and running. The detecting signal of optical disk recording systems is only a tracking error. Hence, the feedforward controller of the proposed tracking control system is constructed based on both Zero Phase Error Tracking (ZPET) control theory and prediction of tracking error. The experimental results point out that the proposed tracking servo system has a quick and precise tracking response and keeps the residual tracking error below its tolerance. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(4): 60– 68, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20257     

Achievement method of high‐speed response of error prediction tracking control for optical disk system

This paper proposes the new design method of error‐prediction control systems combining the ZPET control and the robust feedback control. The error‐prediction control system based on ZPET control can reduce the tracking error caused by periodic disturbances more efficiently than the conventional repetitive control technique. However, the proposed tracking servo system does not reduce the residual tracking error caused by the low‐pass filter of the feedforward compensation and by the long sampling time. In order to overcome this problem, this paper proposes the new structure of the feedforward tracking control system. The modified ZPET control tracking servo system for optical disk recording system does not include the low‐pass filter and its sampling time becomes faster. On the other hand, the sudden disturbance observer reduces the influence of nonperiodic disturbances. The experimental results point out that the proposed tracking servo system has a precise tracking response against both the periodic disturbances and the nonperiodic disturbances. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 51–59, 2010; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20800     

高精确度伺服转台控制系统中的扰动力矩补偿

摩擦力矩和电机波动力矩是影响高精确度伺服转台控制系统位置跟踪精确度的主要因素。针对系统中摩擦力矩和电机波动力矩等扰动力矩补偿问题,提出一种综合的扰动力矩补偿控制策略。基于摩擦观测器提出一种PD前馈控制方法,对系统中的动态摩擦力矩进行了补偿,并利用Lyapunov稳定性理论对所提出的方法进行了系统稳定性分析。结合基于重复控制器的扰动观测器进一步提出一种综合的扰动力矩补偿控制策略。一方面,摩擦补偿方法可以对系统中的摩擦力矩进行补偿;另一方面,插入的重复控制器可以很好地抑制系统中的周期性波动力矩,而扰动观测器则用来补偿重复控制及摩擦补偿时给系统带来的不确定性。仿真结果证明了所提出的方法的有效性。     

A study on higher‐order disturbance observer and robust stability

In earlier papers, it has been reported that a fast and precise servo system, which has low sensitivity to parameter variation and disturbance, can be realized with simple structure by using a high‐order disturbance observer. However, no clear and simple design method satisfying specifications for robust stability, the influence of measurement noise, and relative stability (damping characteristics) for large parameter variation has been proposed. In this paper, we clarify the class of robust servo systems realized by adjusting the order of the disturbance observer and the control parameters. We apply this strategy to the design of a second delay system, such as a position servo system, and realize a high‐performance robust servo system using a high‐order disturbance observer. © 1999 Scripta Technica, Electr Eng Jpn, 128(1): 37–44, 1999     

基于七阶EKF的永磁直线伺服系统变质量估计和扰动补偿

永磁直线同步电动机(PMLSM)伺服系统易受摩擦力和推力波动等外部扰动的影响,为保证系统按照期望轨迹运动,需要对这些扰动进行补偿,而且系统质量信息的准确性对扰动补偿能力有很大影响。针对这一问题,提出一种基于扩展卡尔曼滤波器(EKF)的变质量估计和扰动补偿方法。首先,建立与电机位置有关的扰动模型,作为扰动补偿器。然后,采用七阶EKF计算电机初始位置、估计质量的变化并反映到扰动补偿器中,同时通过自适应律整定扰动模型系数确保扰动模型与实际扰动保持同步,实现对系统的变质量估计和扰动补偿。实验结果证明了所提控制方案的有效性与可行性,明显提高了系统的位置跟踪性能和抗扰性能。     

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。     

高精度永磁直线同步电动机伺服系统鲁棒位置控制器的设计

详细地介绍了高精度,微进给永磁直线交流同步电动机（ＰＭＬＳＭ）驱动系统鲁棒位置控制器的设计,首先,在空载情况下,由静态实验获得非线性摩擦系数模型,通过前馈磨擦补偿器补偿非线性摩擦,其次,由递推最小二乘估计器ＲＬＳ和负载扰动力观测器构成的估计器,估计动子质量,粘滞摩擦系数我载扰动力,设计积分一比例ＩＰ位置控制器以满足跟踪指令和抑制扰动,将观测的负载扰动力前馈,进一步增强系统的鲁棒性。     

Precision motion control of a small launching platform with disturbance compensation using neural networks

A kind of launching platform driven by two permanent magnet synchronous motors which is used to launch kinetic load to hit the target always faces strong parameter uncertainties and strong external disturbance such as the air current impulsion which would degrade their tracking accuracy greatly. In this paper, a practical method which combines adaptive robust control with neural network‐based disturbance observer is proposed for high‐accuracy motion control of the launching platform. The proposed controller not only accounts for the parametric uncertainties but also takes the external disturbances into account. Adaptive control is designed to compensate the former, while neural network‐based disturbance observer is designed to compensate the latter respectively and both of them are integrated together via a feedforward cancellation technique. A new kind of parametric adaptation and weight adaptation strategy is designed by using the linear combination of the system's tracking error and the weight estimation error as a driving signal for parametric adaptation and disturbance approximation. The stability of the novel control scheme is analyzed via a Lyapunov method and this method presents a prescribed output tracking performance in the presence of both parameter uncertainties and unmodeled nonlinearities. Extensive comparative simulation and experimental results are obtained to verify the high‐performance of the proposed control strategy. Copyright © 2016 John Wiley & Sons, Ltd.     

Sliding mode control for a class of uncertain nonlinear system based on disturbance observer

In this paper, a sliding mode control (SMC) scheme is proposed for a class of nonlinear systems based on disturbance observers. For a nonlinear system, the disturbance that cannot be directly measured is estimated using a nonlinear disturbance observer. By choosing an appropriate nonlinear gain function, the disturbance observer can well approximate the unknown disturbance. Based on the output of the disturbance observer, an SMC scheme is presented for the nonlinear system, and the stability of the closed‐loop system is established using Lyapunov method. Finally, two simulation examples are presented to illustrate the features and the effectiveness of the proposed disturbance‐observer‐based SMC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

Force‐based disturbance observer for dynamic force control and a position/force hybrid controller

In this paper, a force‐based disturbance observer (DOB) and a force control system using the DOB are proposed to obtain dynamic force control under disturbances. A DOB can reduce the effect of disturbances and modeling errors on robots. In a conventional DOB, an acceleration response is fed back to a reference, enabling highly precise position control. In other words, the effect of disturbances is decreased by emphasizing the effect of inertial forces. When a force controller is implemented, however, inertial forces are regarded as disturbances respect to a force response. Because inertial forces increase according to the acceleration, conventional DOBs are not suitable for dynamic force control. In the proposed DOB, a force response is fed back instead of an acceleration response. The effect of inertial forces is thus eliminated, thereby improving the tracking performance of force controllers. The proposed method's validity is verified analytically and experimentally. A position/force hybrid controller and a DOB for the controller are proposed as an extension of the proposed DOB. A bilateral controller is given as an example of the proposed hybrid controller, and its tracking performance is demonstrated experimentally. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

活塞加工中的周期性参考与干扰信号的鲁棒二自由度控制

在中凸变椭圆活塞车削过程中,系统的快速跟踪性能和抗扰性能是两个关键问题.由于系统的参考信号和干扰信号都具有按椭圆规律周期变化的特点,针对直线伺服驱动系统研究了对参考信号的跟踪和对变化负载扰动的抑制,提出零相位误差跟踪控制(ZPETC)和改进型重复控制相结合的二自由度鲁棒跟踪控制策略,以解决跟踪控制性能和抗扰性能之间的矛盾.从而既提高快速跟踪能力,又减小负载扰动对刀具定位的影响,仿真结果验证了此方案的有效性.     

Advanced motion control by multi‐sensor‐based disturbance observer

Motion control has been widely used in industry applications. One of the key technologies of motion control is a disturbance observer, which quarries a disturbance torque of a motion system and realizes a robust acceleration control. The disturbance observer can observe and suppress the disturbance torque within its bandwidth. Recent motion systems have begun to spread in society and are required to have the ability to make contact with the unknown environment. Such a haptic motion requires a much wider bandwidth. However, since the conventional disturbance observer attains the acceleration response by the second‐order derivative of position response, the bandwidth is limited because of the derivative noise. This paper proposes a novel structure of a disturbance observer. The proposed disturbance observer uses an acceleration sensor for enlargement of bandwidth. Generally, the bandwidth of an acceleration sensor is from 1 Hz to more than 1 kHz. To cover the DC range, the conventional position sensor‐based disturbance observer is integrated. Thus, the performance of the proposed multisensor based disturbance observer (MSDO) is superior to the conventional one. The MSDO is applied to position control (infinity stiffness) and force control (zero stiffness). The experimental results show the viability of the method proposed. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

中凸变椭圆活塞直线伺服系统的变增益零相位误差跟踪-滑模控制

针对中凸变椭圆活塞直线伺服驱动系统,提出了变增益零相位误差跟踪-滑模控制这一新型控制策略,以提高系统的跟踪性能和抗扰性能.它结合了变增益零相位误差跟踪控制器的理想跟踪特性与滑模控制器的抗扰动能力的优点,并采用扰动观测器对负载扰动进行估计和补偿,从而保证了中凸变椭圆活塞直线伺服驱动系统的快速稳定性.仿真结果表明,采用这种控制策略可以十分有效地减小中凸变椭圆活塞直线伺服驱动系统的跟踪误差.     

永磁直线同步伺服系统混合递归模糊神经网络控制

针对直线电机易受诸多不确定因素的影响，提出了采用递归模糊神经网络和扰动观测器的控制方案。系统采用IP位置控制器；扰动观测器将所观测的扰动力前馈，提高了系统的抗干扰能力。为改善系统受到突加减扰动时的伺服性能，引进了递归模糊神经网络补偿器，采用动态反馈学习算法，在线调整。仿真结果表明，该控制方案可以有效增强系统的鲁棒性。     

Robust design of vibration suppression control system for crane using sway angle observer considering friction disturbance

It is desirable for a container crane to operate smoothly and quickly. For this purpose, the control system of a container crane should be capable of antisway control for suppressing vibrations. A vision sensor system is often used to detect the sway angle. However, since a control system with a vision sensor has a delay time when determining the angle, it sometimes leads to deterioration of control performance owing to the delay time. In order to overcome this problem, this paper proposes a new antisway crane control system based on a dual‐state observer with sensor‐delay correction. However, because of nonlinear friction in the crane, the estimation accuracy achieved by using the observer is poor. To overcome this problem, this paper proposes a disturbance observer considering friction disturbance. The control performance and e?ectiveness of the proposed robust control system based on the estimated information are shown to be satisfactory by experimental results. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 36–46, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22412     

Improving transparency of bilateral control system by sliding mode assist disturbance observer

Transparency is an important indicator to evaluate the performance of a bilateral control system. Uncompensated disturbances in high frequency degrade the transparency in the traditional disturbance observer (DOB) based bilateral control. This paper analyzes the influence of the uncompensated disturbances, and proposes a sliding mode assist disturbance observer (SMADO) to solve the problem. The sliding mode technique helps the original DOB to estimate the disturbances in high frequency by making use of a rapid switching control value. The required switching gain is small in the proposal, which is good for alleviating the chattering. Moreover, to avoid conservative and arbitrary design of the switching gain, a reasonable benchmark is proposed by employing the estimation error between the original DOB and another parallel DOB with a different cutoff frequency. The validity of the proposal is confirmed by experiments. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于摩擦补偿的伺服转台自抗扰控制策略研究

摩擦非线性扰动是影响伺服跟踪系统控制性能的主要因素之一。为提高转台伺服系统的跟踪性能,提出了一种基于Elastoplastic摩擦模型的改进自抗扰控制方法。首先,建立了转台伺服系统的状态空间模型;其次,采用Elastoplastic摩擦模型描述系统中的非线性摩擦扰动,并用遗传算法辨识了模型参数;最后,基于辨识获得的Elastoplastic摩擦模型,将位置误差和速度误差作为不同的参数分别应用到扩张状态观测器,设计了一种改进型自抗扰控制器。未引入摩擦补偿时的速度跟踪误差平均值约为0.0024 rad/s,而加入补偿后的速度跟踪误差平均值减少为0.00147 rad/s。仿真和实验结果表明,本文提出的控制方案能够提高转台伺服系统的跟踪性能,验证了所提出控制方法的有效性和鲁棒性。     

直线伺服推力纹波扰动补偿及自适应振动抑制

针对高速运动的直线伺服系统同时存在的扰动与共振问题,建立两个回路分别进行扰动补偿与共振抑制。通过实验方法建立包含推力纹波扰动的直线伺服系统模型结构,采用最小二乘法进行模型参数的迭代辨识,并通过前馈进行扰动补偿;针对直线伺服系统模型结构中存在的共振现象,通过辨识主导振动频率,采用自适应FIR陷波滤波器抑制主导共振频率所带来的影响。在直线伺服运动控制平台上进行的算法验证实验表明:所建立的两个回路能有效补偿推力纹波扰动与抑制共振,提高直线伺服系统的在高速运行过程中的位置跟踪精确度的作用,满足高速、高精确度轨迹控制要求。     

基于DSP的直线电机位置伺服控制策略研究

在综合分析直线电机位置伺服控制系统的动静态性能及抗干扰能力的基础上,对其位置伺服控制策略进行了研究,开发了一套基于DSP的直线电机位置伺服控制系统。该伺服系统提出了用模糊自适应PID控制方法和干扰观测器补偿技术来提高系统的动静态性能,且可以补偿因外力等对系统造成的干扰。重点分析了位置角对系统的影响,进而提出了模型参考自适应算法对位置角进行校正以消除直线电机定位时出现的振荡。实验结果表明,所提出的位置伺服控制系统具有高的动、静态性能。     

基于扰动观测和补偿的PMSM伺服系统位置跟踪控制

针对存在参数摄动和外部扰动力矩的PMSM伺服系统位置跟踪控制问题,提出一种基于扰动观测和补偿的滑模控制方法。采用扰动观测器估计系统参数摄动以及负载力矩,并在此基础上对等效扰动进行补偿,减小了模型不确定性对系统控制性能影响,系统的位置跟踪误差由0.85 rad减小到0.35 rad;在保证系统稳定性的前提下,去除了常规滑模控制中的不连续控制项,有效地减小了抖振。实验结果表明,与工程上常用的PID算法相比,基于扰动观测和补偿的滑模控制算法不仅能够显著提高PMSM伺服系统的位置跟踪精度,而且能有效地削弱抖振。