极点约束不确定系统非脆弱滤波器的设计

针对一类具有参数不确定性的线性系统,研究其闭环极点区域约束下的鲁棒非脆弱滤波器的设计问题．在对象及滤波器同时存在不确定性的情况下,控制目标要求闭环系统鲁棒稳定,干扰抑制性能指标小于给定的上界,并且闭环极点配置于复平面上指定的圆盘内．针对系统和滤波器具有乘法增益摄动的情况,以线性矩阵不等式的形式给出了非脆弱滤波器的可解性条件．数值算例表明了该方法的有效性．

     

圆盘区域极点约束鲁棒非脆弱控制

针对一类参数不确定线性系统,研究了具有圆盘区域极点约束的状态反馈鲁棒非脆弱控制器设计问题.系统中的参数不确定性满足范数有界条件,设计的非脆弱控制器具有加性和乘性不确定项.基于线性矩阵不等式(LMI),提出了将闭环系统极点配置到指定圆盘区域的状态反馈鲁棒非脆弱控制器存在的充分条件.然后利用G辅助变量替换技术拓展了圆盘极点配置的线性矩阵不等式(LMI)条件,提出保守度较低的状态反馈非脆弱控制器设计方法.数值仿真例子验证了给出的控制器设计方法的可行性.     

Delta算子系统具有极点约束的鲁棒非脆弱方差控制

研究Delta算子描述的线性不确定系统具有圆形区域极点约束的鲁棒非脆弱方差控制问题. 针对系统参数范数有界不确定性和控制器的乘性增益不确定性, 运用线性矩阵不等式(LMI)方法, 提出具有圆形区域极点约束的状态反馈鲁棒非脆弱方差控制器存在的条件和设计方法. 数值算例表明设计方法的可行性.     

基于互质因子摄动的系统非脆弱鲁棒解耦控制

研究对象和控制器存在互质因子不确定性时闭环系统鲁棒稳定和非脆弱鲁棒解耦控制问题,得到了闭环系统具有鲁棒稳定性和鲁棒解耦性能的充分条件,给出了鲁棒控制器的优化设计方法.     

一类不确定时滞奇异系统的鲁棒非脆弱控制

针对不确定奇异时滞系统,研究了鲁棒非脆弱控制问题.假定不确定性范数有界,设计了基于观测器的控制器,使得闭环系统在不确定性影响下保持鲁棒稳定.仅通过求解相应线性矩阵不等式就可得到鲁棒状态反馈控制器,该控制器不仅对所有容许的系统不确定性使相应的闭环系统渐近稳定,而且满足控制器本身是非脆弱的,达到抑制干扰的效果.     

一类不确定时滞奇异系统的鲁棒非脆弱控制

针对不确定奇异时滞系统，研究了鲁棒非脆弱控制问题。假定不确定性范数有界，设计了基于观测器的控制器，使得闭环系统在不确定性影响下保持鲁棒稳定。仅通过求解相应线性矩阵不等式就可得到鲁棒状态反馈控制器，该控制器不仅对所有容许的系统不确定性使相应的闭环系统渐近稳定，而且满足控制器本身是非脆弱的，达到抑制干扰的效果。     

基于T-S模型的非线性系统非脆弱极小极大控制

研究一类非线性离散系统的鲁棒非脆弱极小极大控制问题.针对含有不确定项的非线性离散系统,构造T-S模型,引入参数不确定项,使得模糊模型能够更精确逼近原系统.考虑系统和控制器同时含有不确定性,利用线性矩阵不等式(LMI)处理方法和Lyapunov稳定性理论,设计鲁棒且非脆弱的控制器.考虑不确定性使得性能指标最大的情形,得到极小极大鲁棒非脆弱控制器存在的充分条件.引入凸优化算法,求解使闭环系统渐近稳定且性能指标上界最小的最优极小极大鲁棒控制器的参数.最后以著名的truck-trailer模型为例的仿真结果表明所设计的控制器具有良好的鲁棒性和非脆弱性.     

区域极点约束非脆弱鲁棒飞行控制器设计

研究飞行控制系统性能优化问题,针对区域极点约束条件下飞行控制系统非脆弱鲁棒控制器设计,飞控系统含有外部扰动,为了保证飞控系统的鲁棒性和响应品质,提出用模型参数摄动和加性控制器增益摄动的鲁棒控制,根据线性矩阵不等式理论,给出了非脆弱鲁棒控制器的可解性条件.同时为保证系统具有良好的动态特性,将闭环极点配置在复平面上指定的圆盘区域内.并用鲁棒控制和极点配置结合,给出满足鲁棒性、非脆弱性、干扰抑制性能和动态响应特性的控制器进行仿真.仿真结果表明控制器系统满足多目标控制要求,证明方法的可行性和有效性.     

一类不确定参数系统鲁棒稳定界的解析分析与应用

研究一类具有不确定参数系统鲁棒性稳定界的解析分析方法.在定义了鲁棒稳定界的基础上,证明了鲁棒稳定界只与标称系统的最小特征值有关.利用这一结论不仅可以方便地分析多项式的稳定性,而且可以根据系统的不确定性设计闭环控制系统的期望极点,并进行极点配置.     

圆形区域内鲁棒极点配置优化

本文基于和声搜索算法将精确极点配置的思想推广到圆形区域极点配置,通过对圆域内极点全局优化的方法,实现圆域内鲁棒极点配置问题.首先,基于几何原理描述极点在圆形区域内的位置信息,确定了在圆形区域内动态选择极点的规则,可以保证算法在圆形区域内动态选取极点.然后,对圆形区域内的极点,基于精确鲁棒极点配置的思想,利用和声搜索算法优化摄动或不确定性的谱范数上界,从而得到一组允许闭环系统具有更大摄动或不确定性的极点及相应的状态反馈控制器.最后,通过实例进行仿真,仿真结果表明本文采用和声搜索算法全局优化动态选择极点方法得到的闭环系统具有更好的鲁棒性.     

A peak filtering method with improved transient response for narrow-band disturbance rejection in hard disk drives

Peak filtering methods are commonly used in track-following control of hard disk drives (HDDs) to suppress narrow-band disturbances around a specific frequency. When there are significant plant dynamics within the bandwidth of the filter, the closed-loop system is prone to be unstable due to the lightly damped poles of the filter, as well as lightly damped poles of the plant. On the other hand, settling response of such peak filters during shock disturbances is slow, and increases tremendously with decreasing damping ratios. In this article, we present a novel design of peak filters with improved transient responses using a phase scheduling method in addition to varying gain and damping ratio. By doing so, the stability margin of the closed-loop systems during both transient stage and steady-state stage will be improved. The effectiveness of the proposed methodology is verified with extensive simulations and the proposed method is then applied in an integrative servo analysis platform to carry out a scaling exercise to evaluate and predict servo performance to support 10 Terabits/in².     

Repetitive control of servo systems with time delays

In many industrial robotic servo applications there is a need to track periodic reference signals and/or reject periodic disturbances. Moreover, time-delays are usually unavoidable in control systems due to the sensoring and communication delays. This paper presents an alternative repetitive control design for systems with constant time-delays in both forward and feedback control channels, which are dedicated to track/reject periodic signals. An additional delay is introduced together with the plant delays to construct an internal model for periodic signals, and a simple compensator based on the plant model inverse is utilized to stabilize the closed-loop system. Sufficient stability conditions of the closed-loop system and the robustness analysis against modeling uncertainties are studied. The proposed idea is further extended for general time-delay systems with only a delay term in the forward control channel. The “plug-in” structure used in conventional repetitive control designs is avoided, so that it leads to a simpler control configuration, i.e. only a proportional parameter and the cutoff frequency of a low-pass filter are required to be selected. Simulations based on a hard disk drive system and practical experiments on a rotary robotic servo system are provided to evaluate the effectiveness of the proposed method.     

Track-following control of a dual-stage hard disk drive using a neuro-control system

This paper describes the track-following control of a dual-stage hard disk drive system using neural-networks. A neural-network approach to on-line learning control, and a real-time implementation for a dual-stage hard disk drive, are presented. The use of the dual-stage actuator in hard disk drive systems has become a means of achieving increased servo actuator bandwidth. The dual-stage actuator presented here uses a voice-coil motor (VCM) as a coarse actuator, and a piezoelectric actuator (PZT) as a fine actuator. The control system consists of a series combination of both a plant with a feedback loop and a neural-network with a feedforward loop. The neural-network functions as the reference input filter, and it organizes a new reference signal to the closed-loop circuit. Numerical and experimental results for the track-following control system of the dual-stage hard disk drive show the validity of the proposed neuro-control system.     

自适应闭环H1滤波在组合导航系统中的实现研究

针对常规H∞滤波在组合导航系统中滤波精度不高的问题,采用闭环反馈的方法对滤波加以改进;并在闭环H∞滤波迭代方程中引入遗忘因子,利用量测噪声的变化自适应调整滤波增益,构成自适应闭环H∞滤波.理论分析表明,该改进的滤波算法降低了噪声十扰,但不影响H∞滤波本身的鲁棒性.无源北斗/SINS组合导航系统跑车数据的半物理仿真进一步表明,自适应闭环H∞滤波下的组合导航精度明显优于采用开环H∞滤波或不带有遗忘因子的闭环H∞滤波算法的导航精度,从而验证了改进滤波算法的有效性.     

Monotonicity and stabilizability- properties of solutions of the Riccati difference equation: Propositions, lemmas, theorems, fallacious conjectures and counterexamples

The problem considered is that of selecting an initial covariance matrix for the Kalman filter to ensure that the closed-loop filter at every subsequent time instant is exponentially asymptotically stable as a time-invariant filter. Sufficient conditions are derived based on monotonicity properties of the solution of the Riccati difference equation. The results have application in observer design, and the cases of filtering for nonstabilizable systems and systems with singular system matrices are included.     

离散非线性系统的鲁棒模糊协方差控制

针对T-S模糊模型描述的一类不确定非线性离散系统，研究使闭环系统的稳态方差小于某个给定上界，同时闭环极点位于给定圆盘中的状态反馈鲁棒协方差控制律设计问题，并导出以一组线性矩阵不等式表示的控制律的存在条件。     

Differential evolution based high-order peak filter design with application to compensation of contact-induced vibration in HDD servo systems

Sensitivity loop shaping using add-on peak filters is a simple and effective method to reject narrow-band disturbances in hard disk drive (HDD) servo systems. The parallel peak filter is introduced to provide high-gain magnitude in the concerned frequency range of open-loop transfer function. Different from almost all the known peak filters that possess second-order structures, we explore in this paper how high-order peak filters can be designed to improve the loop shaping performance. The main idea is to replace some of the constant coefficients of common second-order peak filter by frequency-related transfer functions, and then differential evolution (DE) algorithm is adopted to perform optimal design. We creatively introduce chromosome coding and fitness function design, which are original and the key steps that lead to the success of DE applications in control system design. In other words, DE is modified to achieve a novel design for hard disk drive control. Owing to the remarkable searching ability of DE, the expected shape of sensitivity function can be achieved by incorporating the resultant high-order peak filter in parallel with baseline feedback controller. As a result, a seventh-order peak filter is designed to compensate for contact-induced vibration in a high-density HDD servo system, where the benefits of high-order filter are clearly demonstrated.     

Detection filter design: Spectral theory and algorithms

A new formulation of the detection filter problem is generated by assignment of the closed-loop eigenstructure under certain constraints. Detection filters, which are actually a specific class of observers, fix the output error direction of the system so that it can be associated with a particular failure mode and its known design failure direction. The derivation of detection filters from an eigensystem assignment approach permits a very transparent theory. The detection filter gains and closed-loop eigenvectors are obtained from a set of simultaneous equations. Necessary and sufficient conditions for the solution of these algebraic equations are determined which produce a complete theory for detection filters.     

一种鲁棒故障检测与反馈控制的最优集成设计方法

研究线性不确定系统的反馈控制器与鲁棒故障检测滤波器集成设计问题.基于新提出 的性能指标函数,将鲁棒故障检测滤波器设计问题归结为最优化问题,通过求解Riccati方程可 得到鲁棒故障检测滤波器设计问题的最优解.在共用同一状态观测器的情况下,将反馈控制器 和鲁棒故障检测滤波器的集成设计问题归结为两目标优化问题,解决了同时满足闭环控制系统 设计要求和故障诊断系统鲁棒性能的最优集成设计问题.简例验证了提出算法的有效性.     

Evolutionary design and implementation of a hard disk drive servo control system

The ever increasing demand for higher storage capacity and smaller magnetic hard disk drives have driven the need of developing a high performance head positioning servo control system. To meet the challenge, this paper presents the design and real-time implementation of a robust two-degree-of-freedom servo system for physical 3.5-in. hard disk drive with single voice-coil-motor actuator using a multi-objective evolutionary algorithm toolbox. Besides the simplicity in controller structure, such an evolutionary servo control system is capable of meeting various performance specifications of hard disk drives in both the time and frequency domains. It is shown that the servo system optimally moves the magnetic head onto the desired track with minimal control effort, and keeps it on the track robustly against plant uncertainties or runout disturbances. Validation results of the evolutionary servo control system are compared with classical PID and RPT controllers, which show excellent closed-loop response and robustness in the face of practical perturbations in HDD.