Speed tracking control for the gimbal system with harmonic drive

This paper presents a composite controller based on a disturbance observer for the gimbal system of double-gimbal magnetically suspended control moment gyro (DGMSCMG) with harmonic drives. The controller removes the influence by coupling moments and nonlinear transmission torques. The disturbances are estimated by the designed disturbance observer. By introducing a state feedback controller, the disturbances can be eliminated from the output channel of the system. The gain selection principle of the disturbance observer is also analyzed. Both the simulation and experimental results indicate that the proposed control method can reject mismatched disturbances and improve system performance.     

Robust nonlinear control of shunt active filters for harmonic current compensation

An advanced control strategy of shunt active filters (SAF) aiming to compensate for harmonic current in the electric supply grid is proposed. The SAF considered here is suitable for three-phase three-wire current harmonic compensation and is based on AC/DC three-phase boost converter topology. Robust control of the active-reactive current/power delivered by the SAF is designed exploiting the internal model principle. The stabilization of the DC-link voltage dynamics is addressed along with the fulfillment of the harmonics compensation objective. The two-time scale behavior of the SAF is exploited to apply the averaging theory in the control design. Experiments are provided to show the effectiveness of the proposed solution.     

Adaptive control of harmonic drive with parameter varying friction using structurally dynamic wavelet network

In this paper, an adaptive controller with structurally dynamic wavelet network is developed for a harmonic drive subject to parameter varying friction. The control architecture integrates a proportional controller, a feedback adaptive component and sliding component to adaptively compensate for the friction to achieve accurate position tracking. Global asymptotic stability of the algorithm is proved by using Lyapunov function. In parallel to the adaptive controller, a fuzzy reconfiguration scheme is devised to change the structure of the network along with weights updating to improve the system tracking performance and robustness. Experimental tests on a harmonic drive manipulator verify the effectiveness of the proposed control method.     

油井作业中传感器误差补偿方法的研究

为了提高油井作业中压力传感器的测量精度,提出了一种基于粒子群优化BP神经网络的误差补偿方法.利用粒子群算法的全局寻优和收敛速度快的特点,训练网络的权值,能有效地改善BP神经网络传统算法的收敛速度和学习能力.结果表明:这种方法大大提高了压力传感器在油井作业中的测量精度和稳定性,也提高了油田作业的工作效率.     

多传感器电子秤非线性补偿电路的研究

介绍了改进多传感器电子秤的计量精度及稳定性的实现方案。根据称重系统在实际应用过程中的测量精度情况,对系统中所用传感器作受力分析。通过对影响称重系统精度的性能指标因素的研究,改进称重系统结构,增强系统稳定性。讨论并分析多传感器系统非线性造成的原因,根据传感器的输入输出特性曲线,应用动态补偿电路对多传感器进行线性化处理,从而以硬件手段实现系统的优化,使电子秤称重系统精度和稳定性得到了很大改善。     

Vibration analysis of a contact slider/gimbal of a flexible disk drive

 To design contact-type gimbal system for a newly developed removable flexible disk drive called Card size flexible disk drive (CFDD) (Shinpuku et al., 2001; Ryoson et al., 2001), the gimbal's vibration characteristics in the disk-rotation direction were measured and simulated using FEM. To determine the relationship between vibration and friction in the head disk interface (HDI), a hard disk was also used. The friction characteristics were inserted into the FEM model based on the results. The gimbal was modified to suppress vibration amplitude to half in both simulation and experiment. Received: 5 July 2001/Accepted: 1 November 2001 Paper presented at the 12th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 28–29 June, 2001.     

Adaptive bearing friction compensation based on recent knowledge of dynamic friction

Gimbal bearing friction is a major source of stabilization errors for airborne pointing and tracking systems. This paper describes a novel addition to conventional stabilization techniques which has recently been incorporated in such a system to greatly improve stabilization performance. This addition contains a model in system software which predicts realtime friction torque values. This new, dynamic friction model, which is the result of recent investigations into dynamic friction characteristics, is adaptively adjusted into agreement with actual friction behavior by processing inputs from conventional system sensors. Measurements from these sensors cause on-line adjustment of model parameters, resulting in ‘adaptive’ compensator action. The model's output is used to generate an addition to conventional stabilization subsystem commands. The resulting additional gimbal motor torque is equal and opposed to the actual friction disturbance such that the residual torque, and hence stabilization errors, are a small fraction of those for an uncompensated system. The model-referenced compensator thus operates in a predictive, adaptive, feedforward manner to pre-condition the stabilization subsystem, reducing stabilization errors well below levels which are achievable through conventional feedback operation alone.     

数字助听器中新的非线性响度补偿方法的研究

数字助听器中的多通道响度补偿算法,通常是在划分出的多个频段内分别进行补偿,这在一定程度上会导致共振峰结构的破坏,造成语义信息的曲解或丢失。一种新的非线性的响度补偿方法的提出,无需进行频段的划分,并且根据听损患者在不同频率上对声音强弱的实时感知特性对语音信号进行补偿。该方法不仅使补偿后语音的响度完全映射到听者的听觉范围内,还使得补偿后的响度曲线在轮廓上与原始语音基本保持一致。实验中,小波去噪和移频技术的运用保证了处理效果更加优良。结果表明,该方法能有效提高语音响度和改善听损患者的言语识别率,具有一定的应用价值。     

A numerical study of the dimple/gimbal interface in a hard disk drive

A finite element (FE) model for the dimple/gimbal interface of a hard disk drive is developed as a function of normal load, friction coefficient, material properties and dimple geometry. The air bearing force is approximated as a normal load acting on the slider. A rotational acceleration was applied to the dimple to simulate accessing of a hard disk drive suspension during seeking. Results for the relative displacement between the dimple and the gimbal are determined for a typical suspension as a function of normal load, rotational acceleration, friction coefficient, material properties and geometrical parameters of suspension and flexure.     

An experimental study of the dimple/gimbal interface in a hard disk drive

The contact of the dimple/gimbal interface in a hard disk drive was studied experimentally. Two types of dimples with different surface roughness and several types of gimbal materials were investigated. The load?Cdisplacement curves for the contact of the dimple and the gimbal exhibit hysteresis, which is related to the plastic deformation of the asperities, during the first few load/unload cycles. The roughness of dimple and gimbal samples was measured before and after load?Cunload testing using an AFM. The plasticity index was determined based on the roughness measurement. The results show that the roughness and plasticity index of the non-polished dimple decrease with the number of load/unload cycles significantly, i.e., the contact surface becomes smoother than the original surface due to plastic deformation. The roughness and plasticity index of the laser-polished dimple change slightly before and after the load?Cunload test.     

自校正调节器在具有阻力负载的气动位置伺服系统中的应用

以空气为传输介质的气动位置伺服系统,由于自身结构的特殊性,难以实现高精度位置控制.为研究工作过程中气缸所受柔性作用力,并真实反映气动系统的控制过程,利用气缸模拟实际环境中系统的负载外力,采用三阶模型描述系统,并运用自校正调节器完成了对系统控制律的设计;最后通过实验研究了自校正调节器对气动位置伺服系统的动态、静态特性的影响并根据仿真实验结果分析了气动系统跟踪响应迟滞性的根本原因.     

基于APF的谐波补偿中的几种谐波电流检测方法

采用有源电力滤波器（APF）已成为谐波补偿的一种重要趋势，而采用这种方式的关键是能够准确地检测出谐波电流，本文介绍了几种基于APF的谐波补偿中的谐波电流检测方法，并对它们进行了比较。     

Adaptive friction compensation of servo mechanisms

In this paper, adaptive friction compensation is investigated using both model-based and neural network (non-model-based) parametrization techniques. After a comprehensive list of commonly used models for friction is presented, model-based and non-modelbased adaptive friction controllers are developed with guaranteed closed-loop stability. Intensive computer simulations are carried out to show the effectiveness of the proposed control techniques, and to illustrate the effects of certain system parameters on the performance of the closed-loop system. It is observed that as the friction models become complex and capture the dominate dynamic behaviours, higher feedback gains for model-based control can be used and the speed of adaptation can also be increased for better control performance. It is also found that neural networks are suitable candidate for friction modelling and adaptive controller design for friction compensation.     

基于自抗扰控制的伺服系统摩擦补偿研究

伺服系统中由于摩擦的非线性和不确定性,严重影响了系统的控制性能。为抑制摩擦对系统性能的影响,设计了一个线性的自抗扰控制器进行摩擦补偿控制。该控制器无需任何系统的模型信息,可将摩擦作为扰动实时估计,并加以补偿。算法简单,鲁棒性强,易于工程实现。对某炮控伺服系统的仿真结果表明,该算法是有效的。     

Numerical analysis of off-track vibration of head gimbal assembly in hard disk drive caused by the airflow

The problem of flow-induced vibration of head gimbal assembly (HGA) in hard disk drive (HDD) is analyzed by means of numerical models. Flow field is calculated in a fraction of physical domain called extended wedge-like domain. For this purpose, appropriate inlet and outlet boundary conditions are specified. The aerodynamic disturbances generated by the slider are studied by performing flow calculations for the cases of with and without slider. It is observed that the slider blocks the airflow causing a high-pressure region in the proximity of the leading surface of the slider. In addition, significant vortical structures are found being generated by the side surfaces of the slider. A finite element model is developed for calculating the response of HGA to the aerodynamic excitations. It is found that the flow disturbances generated by the slider play a significant role in the off-track vibration of the HGA.     

Support vector networks in adaptive friction compensation.

This paper presents our research on how support vector regression (SVR) and parametric adaptive learning, which are normally used independently, can be exploited together to benefit adaptive neural control. In the context of friction compensation for servo-motion control systems, we present the notion of support vector networks which play an essential role in combining SVR and adaptive neural network (NN) in cooperation for friction estimation. The analysis shows that the proposed support vector network contributes not only to the performance improvement but also to the practical usefulness in adaptive friction compensation. Experimental results are reported to demonstrate the effectiveness of the proposed approach.     

Two-step compensation of nonlinear systems

We study the problem of stabilization of nonlinear plants. We show that given a nonlinear plant P, if there exists a (nonlinear) compensator F, possibly unstable, which stabilizes P, then, with P₁: = P(I − F(− P))⁻¹, any C defined by C:= F + Q(I − P₁Q)⁻¹ for some finite-gain stable Q will stabilize P.     

基于自适应模糊神经网络的摩擦力分部补偿算法

针对液压位置跟踪系统中的非线性摩擦力,提出对摩擦力模型的不同分量分别进行补偿的分部补偿算法,以解决用模糊神经网络(FNN)对摩擦力整体进行补偿时,因摩擦力非光滑特性引起较大逼近误差的问题．实验结果表明,分部补偿算法能对摩擦力非线性进行有效补偿,使系统表现出良好的稳态跟踪性能。     

非线性复合邻域人脸光照补偿

变化的光照是提高人脸正确检测率的瓶颈,提出了非线性复合邻域光照补偿方法来解决人脸检测的光照问题。非线性复合邻域光照补偿方法用对数函数做为基函数,设置的平移系数和分界值系数可以同时对过亮和偏光的图像进行补偿,引入了邻域光照补偿公式解决了传统非线性方法不能针对同一灰度值像素在不同局部应该进行不同补偿的问题。实验结果表明,该方法对过暗和过亮的人脸图像都可以进行有效的光照补偿,熵比较优于传统非线性光照补偿、Gamma校正和直方图归一化。     

红外甲烷传感器非线性动态补偿的研究

红外甲烷传感器作为瓦斯监测主要传感器之一,非线性动态影响到它的测量准确度和测量范围,不利于安全生产.针对这一问题,采用最小二乘支持向量机非线性动态方法对传感器进行补偿,并对算法予以改进.通过仿真实验加以比较,实验结果表明:基于改进最小二乘支持向量机非线性动态补偿,传感器测量准确性和测量范围大大提高,对促进安全生产有积极...