宏微复合运动平台的自抗扰控制研究

摩擦是影响机械导轨运动平台精度的主要原因.宏微复合运动平台将无摩擦的柔性铰链与直线平台结合在一起,利用柔性铰链的弹性变形补偿摩擦死区.然而,柔性铰链的固有频率低,其非线性弹性振动严重影响微平台定位精度.为此,本文设计视弹性振动为扰动的自抗扰控制策略,该方法避免了建立非线性弹性振动精准数学模型的困难,利用扩张状态观测器主动估计弹性振动及不确定性,并在微平台位置环补偿之,以保证微平台定位精度.与此同时,在控制律中加入加速度前馈以提高系统响应速度.对于宏平台,采用PID控制作为宏平台位置环的控制策略,并通过宏微双级驱动方式补偿受机械导轨非线性摩擦带来的影响.实验对比结果表明,自抗扰控制在受非线性弹性振动影响时,其抗扰性能、跟踪性能优于传统的PID控制,可保证微平台良好的定位精度.     

基于模糊AKF地磁辅助导航的采煤机定位方法

针对惯导在采煤机定位时产生累积误差以及实时定位精度低等问题,提出了基于模糊自适应卡尔曼滤波(AKF)惯性地磁辅助惯性导航的采煤机动态定位方法.通过迭代最近等值点(ICCP)算法将惯导与地磁辅助技术组合,并引入模糊自适应的卡尔曼滤波方法,实现了在线自适应调整测量噪声方差阵.通过对采煤机进行定位仿真分析,结果表明:可克服惯导定位误差随时间累积的缺点,实现了采煤机实时高精度定位.     

Adaptive positioning control of an ultrasonic linear motor system

A 3PRR parallel precision positioning system, driven by three ultrasonic linear motors, was designed for use as the object stage of a scanning electron microscope (SEM). To improve the tracking accuracy of the parallel platform, the positioning control algorithms for the drive joints needed to be studied. The dead-zone phenomenon caused by static friction reduces the trajectory tracking accuracy significantly. Linear control algorithms such as PID (Proportion Integration Differentiation) are unable to compensate effectively for the dead-zone nonlinearity. To address this problem, two types of feedforward compensation control algorithms have been investigated. One is constant feedforward with the integral separation PID; the other is adaptive feedback and feedforward based on the model reference adaptive control (MRAC). Simulations and experiments were conducted using these two control algorithms. The results demonstrated that the constant feedforward with integral separation PID algorithm can compensate for the time-invariant system after identifying the dead-zone depth, while the adaptive feedback and feedforward algorithm is more suitable for the time-varying system. The experimental results show good agreement with the simulation results for these two control algorithms. For the dead-zone nonlinearity caused by the static friction, the adaptive feedback and feedforward algorithm can effectively improve the trajectory tracking accuracy.     

永磁同步电机调速系统的多维泰勒网逆控制

针对永磁同步电机(PMSM)的高性能控制问题,在充分考虑时变特性、不确定性以及测量噪声等随机因素的基础上,通过PMSM的逆系统将被控对象补偿成为具有线性传递关系的系统,提出一种基于改进自适应逆控制的控制方案.采用矢量控制的双闭环控制结构,将多维泰勒网逆控制方法引入速度环.首先,对PMSM数学模型的可逆性进行证明以解决非线性系统逆建模的存在性问题;然后,建立新颖的动态网络化控制器-----多维泰勒网(MTN),其具有结构简单、计算复杂度低的优点;最后,为了实现高精度的速度控制,将3个MTN分别作为实现系统建模的自适应模型辨识器、逆建模的自适应逆控制器和噪声干扰消除的非线性自适应滤波器,并将PMSM的动态响应控制和消除干扰的控制分为相对独立的过程进行,同时实现最优控制.仿真结果表明,所提出控制方案能够实现PMSM伺服系统精确的速度控制,具有良好的跟踪性能和较强的抗干扰能力.     

Swing-arm-type PZT dual actuator with fast seeking for optical disk drive

 In this paper, a swing-arm-type dual positioning mechanism using a voice coil motor (VCM) and bimorph PZT actuators is proposed for the possible application to the future optical disc drive actuator. A VCM is used as a coarse motion actuator, and a set of piezoelectric actuators is used for fine motion. The two pairs of PZT actuators are arranged in parallel and are carefully designed to deflect in `S' shape such that tension and compression forces are generated simultaneously and thus the hysteresis is minimized. The static and dynamic analyses are performed and the parameter studies on the key dimensions of the set of PZT actuators are investigated. For fast seeking motion, time optimal control scheme combined with PD algorithm is adopted for the fast seeking motion of VCM. Positive position feedback (PPF) control is used to suppress residual vibration for the PZT actuator beams by activating it at the end of VCM swing motion. The feasibility of the suggested actuator system and the control scheme is demonstrated through simulations and experiments. Received: 5 July 2001/Accepted: 21 December 2001     

Tracking control of a piezo‐actuated stage based on a frictional model

The tracking control accuracy of a piezoelectric actuator (PEA) is limited due to the actuator's inherent hysteretic nonlinearity. Direct drive of PEA on a positioning stage with friction force will cause control problems. An approximated dynamic model of PEA with consideration of friction force is novel synthesized for control. This model is based on a second‐order transfer function with two parameterization terms. The first time delay term consists of the hysteresis of piezo effect combined with frictional force lag with varying velocity. The second term is comprised of both presliding and sliding regimes. The H‐infinite tracking controller is designed to compensate for the structural uncertainty associated with time delay and the unstructured frictional force in the PEA stage. Iterative Learning Control is implemented to reduce the unmodeled repetitive error by a factor of 20. Numerical simulations and experimental tests consolidate the root mean square (RMS), positioning error close to the hardware reproducibility and accuracy level. Experimental results show the controlled stage can be potentially used for precise positioning. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

MODELING OF A PIEZO‐ACTUATED POSITIONING STAGE BASED ON A HYSTERESIS OBSERVER

Piezo‐actuated positioning stages contain two parts: a Piezo Electric Actuator (PEA) and a positioning mechanism. The tracking control accuracy of the piezo‐actuated positioning stage is limited due to the hysteretic nonlinearity of the PEA and the friction behavior of the positioning mechanism. This loss in precision restricts the use of the piezo‐actuated stage in an ultra‐high‐precision optical system. This paper presents an inversion‐based approach to reduce the nonlinearity of the PEA by using a proposed hysteresis observer. To reduce the degredation in precision due to the friction behavior of the positioning mechanism, a PI feedback controller with a feed‐forward controller based on a hysteresis observer is proposed to solve tracking problems with modelling uncertainties and external disturbances.     

Stable Adaptive Fuzzy Control with TSK Fuzzy Friction Estimation for Linear Drive Systems

This paper considers the control of a linear drive system with friction and disturbance compensation. A stable adaptive controller integrated with fuzzy model-based friction estimation and switching-based disturbance compensation is proposed via Lyapunov stability theory. A TSK fuzzy model with local linear friction models is suggested for real-time estimation of its consequent local parameters. The parameters update law is derived based on linear parameterization. In order to compensate for the effects resulting from estimation error and disturbance, a robust switching law is incorporated in the overall stable adaptive control system. Extensive computer simulation results show that the proposed stable adaptive fuzzy control system has very good performances, and is potential for precision positioning and trajectory tracking control of linear drive systems.     

基于定转子电阻误差补偿的感应电动机自适应逆解耦控制研究

对于具有多变量、非线性、强耦合、慢时变等特征的异步电动机调速系统, 实现定子磁链与电磁转矩的高精度动态解耦是提高系统性能的关键. 首先通过非线性状态反馈建立感应电动机的积分逆模型, 并在此基础上提出了一个基于定、转子电阻误差补偿的感应电动机自适应逆解耦控制方法, 将补偿后的积分逆模型串联到对象的输入端建立广义被控对象. 复杂的感应电动机调速系统被解耦成电磁转矩与定子磁链的两个独立回路, 利用线性系统理论分别对独立回路进行综合设计, 实现定子磁链和电磁转矩对各自给定值的渐近跟踪. 利用Matlab进行了仿真实验, 实验结果验证了建议方案的有效性和可行性.     

操作器的PID自适应控制

利用操作器动力学模型的性质,提出了一种前馈补偿加PID反馈控制的自适应控制方案.由于在控制力矩中引入积分项,使操作器关节的跟踪精度和抗干扰能力得到提高.本文分析了摩擦干扰和执行机构的惯性对控制方案的影响.本文进一步的研究表明:在许多情况下,只需对操作器动力学中耦合和非线性最强的项进行补偿,然后加PID反馈控制,就能取得较好的控制效果.从而简化了控制方案,以PUMA560的前三个关节的参数作模型,对文中的方法进行了仿真.     

Adaptive feedforward compensation of force ripples in linear motors

In this paper, an adaptive control scheme is proposed to reduce force ripple effects impeding motion accuracy in Permanent Magnet Linear Motors (PMLMs). The displacement periodicity of the force ripple is first obtained by using a Fast Fourier Transform (FFT) analysis. The control method is based on recursive least squares (RLS) identification of a nonlinear PMLM model which includes a model of the force ripple. Based on this model, the control algorithm can be commissioned which consists of a PID feedback control component, an adaptive feedforward component for compensation of the force ripple and another adaptive feedforward component based on the inverse dominant linear model which will serve to expedite motion tracking response. Simulation and experimental results are presented to verify the effectiveness of the proposed control scheme for high precision motion tracking applications.     

非线性离散系统的自适应PID控制器

针对非线性离散系统设计了利用TSK(Takagi Sugeno Kang)模糊模型的自适应PID控制器。利用模糊模型预测控制信号误差,通过控制信号误差自适应PID控制器参数。比较系统输出和模糊模型输出自适应模糊模型的参数。该方法可以弥补系统参数的模糊性、数学模型的模型误差和系统参数的变化。非线性离散系统的仿真实验验证了所设计的自适应PID控制器对非线性离散系统控制的有效性。     

ROBUST ADAPTIVE CONTROL OF PIEZOELECTRIC ACTUATORS WITH AN APPLICATION TO INTRACYTOPLASMIC SPERM INJECTION

This paper describes a robust adaptive control method for positioning piezoelectric actuators (ultrasonic motor) to achieve highly precise motion. The model employed to describe the motor is a second‐order linear model plus a nonlinear part comprising predominantly of a dynamical hysteresis. Based on the model, the overall control algorithm uses a PID component and an adaptive robust component for estimating the parameters of the piezo motor model. The adaptive component is continuously refined based on just prevailing input and output signals. Real‐time experimental results are provided to verify the effectiveness of the proposed scheme when applied to high precision motion trajectory tracking such as Intracytoplasmic Sperm Injection (ICSI).     

基于AKF和RLS的车辆簧载质量辨识研究

实际应用中,车辆负载会随着乘客和货物的变化而发生显著改变.提出结合自适应卡尔曼滤波器(AKF)与递推最小二乘算法(RLS)进行车辆簧载质量的在线辨识.首先,采集四分之一车辆悬架的簧载振动加速度、动行程及车轮垂向加速度信号,对车辆悬架系统中的簧载质量和车轮的绝对速度进行估计,进而由遗忘因子递推最小二乘算法辨识车辆簧载质量.分析了在不同路面等级下,卡尔曼滤波器的过程噪声协方差和测量噪声协方差对悬架状态估计精度的影响.仿真结果显示,在选取与车辆行驶路面等级匹配的过程噪声协方差和测量噪声协方差时,车辆悬架状态参数的估计精度较高,并能够在线准确地辨识得到车辆的簧载质量值.     

利用内置导轨的清洁机器人垂直运动控制

针对建筑物表面清洁机器人(BFMR)容易受环境和振动影响、运行稳定性差等问题,设计了安全稳定的控制系统.在垂直和水平机器人的对接过程中,利用导轨制动系统抑制冲击,并利用再平层过程补偿机器人内置导轨与建筑物表面导轨之间的定位误差.此外,利用提出的振动抑制系统,根据钢丝绳动态属性的状态估计值,控制钢丝绳的加速度,对环境噪声产生的振动进行抑制,提高垂直机器人垂直运动的稳定性和可靠性.实验结果表明,本文设计的控制系统能够有效降低振动影响,具有可行性.     

Optimal design of a 3-PUPU parallel robot with compliant hinges for micromanipulation in a cubic workspace

In recent years, nanotechnology has been developing rapidly due to its potential applications in various fields that new materials and products are produced. In this paper, a novel macro/micro 3-DOF parallel platform is proposed for micro positioning applications. The kinematics model of the dual parallel mechanism system is established by the stiffness model with individual wide-range flexure hinge and the vector-loop equation. The inverse solutions and parasitic rotations of the moving platform are obtained and analyzed, which are based on a parallel mechanism with real parameters. The reachable and usable workspace of the macro motion and micro motion of the mechanism are plotted and analyzed. Finally, based on the analysis of parasitic rotations and usable workspace of micro motion, an optimization for the parallel manipulator is presented. The investigations of this paper will provide suggestions to improve the structure and control algorithm optimization for the dual parallel mechanism in order to achieve the features of both larger workspace and higher motion precision.     

Modeling and Neuro-Fuzzy adaptive attitude control for Eight-Rotor MAV

This paper focuses on modeling and intelligent control of the new Eight-Rotor MAV which is used to solve the problem of low coefficient proportion between lift and gravity for Quadrotor MAV. The dynamical and kinematical modeling for the Eight-Rotor MAV was developed which has never been proposed before. Based on the achieved dynamic modeling, two types of controller were presented. One type, a PID controller is derived in a conventional way with simplified dynamics and turns out to be quite sensitive to sensor noise as well as external perturbation. The second type controller is the Neuro-Fuzzy adaptive controller which is composed of two type-II fuzzy neural networks (TIIFNNs) and one PD controller: The PD controller is adopted to control the attitude, one of the TIIFNNs is designed to learn the inverse model of Eight-Rotor MAV on-line, the other one is the copy of the former one to compensate for model errors and external disturbances, both structure and parameters of T-IIFNNs are tuned on-line at the same time, and then the stability of the Eight-Rotor MAV closed-loop control system is proved using Lyapunov stability theory. Finally, the validity of the proposed control method has been verified through real-time experiments. The experimental results show that the performance of Neuro-Fuzzy adaptive controller performs very well under sensor noise and external disturbances, and has more superiority than traditional PID controller.     

Decreased vibration control for centrifuges: A new adaptive hybrid control technique

This paper presents a new control approach which can restrain the vibration of centrifuges. In the new scheme, changed support stiffness and self-tuning feedforward PID control of the decreased vibration force are effectively combined. Some advanced techniques, (such as adaptive modification for unstable vibration regions, two-level computer control, curve-tracking control, are used to make the centrifuge system run in a minimum-vibration state. A horizontal centrifugal experiment is used to test the new control method. Experimental results show the effectiveness of the proposed scheme.     

模糊PID控制在纳米微动台系统中的应用

针对在纳米级运动控制中,传统PID算法的参数配置在抑制系统运动超调、提高系统定位精度,以及保障系统稳定性等方面存在矛盾的问题,提出了将模糊自适应PID控制器应用于该系统的方案.并基于大量工程整定实验,给出了针对纳米量级控制特点的模糊集设置和模糊整定规则,选取了合理的PID参数论域取值.实验结果表明,所设计的模糊控制器通...     

推进器饱和约束的水面无人艇固定时间精准跟踪控制

针对复杂扰动、完全未知系统动态以及推进器饱和约束的水面无人艇高精度跟踪控制问题,提出一种基于固定时间非奇异终端滑模的无模型固定时间精准跟踪控制(MFPTC)方案.首先,设计有限时间集总观测器,精确重构和补偿集总未知项;其次,引入自适应辅助系统消除推进器饱和特性,使得MFPTC方案在饱和约束下实现期望时间内对预定轨迹的精准跟踪;进而,基于反正切函数构造固定时间幂次趋近律,加快滑模变量收敛速度且有效削弱控制抖振;最后,采用CyberShip Ⅱ实验模型进行仿真研究,结果验证所提出MFPTC方案的有效性与优越性.