可变磁路式永磁悬浮系统的动力学特性研究

介绍一种由伺服电机、盘状径向磁化永磁铁和导磁体组成的可变磁路式永磁悬浮系统。该系统中永磁铁提供悬浮力,伺服电机驱动盘状永磁铁旋转,改变通过悬浮物的磁通量,实现悬浮力的实时控制。该悬浮系统可以实现零吸引力,避免接触吸附问题,可以实现稳定状态下的零功率悬浮,达到节能减排的目的;可以任意改变磁极特性,实现在多自由度系统上的灵活应用。在综合考虑系统漏磁特性的条件下建立系统的参数化模型,分析系统的动力学和控制特性,然后进行系统的悬浮特性仿真研究,结果表明该系统在一定外扰下可实现稳定悬浮,并且具有较理想的时域和频域响应特性。     

可控磁路式并联型永磁悬浮系统

提出一种主要由伺服电机、径向磁化盘状永磁铁、"F"形导磁体及悬浮物构成的可控磁路式并联型永磁悬浮系统。系统中,并联悬浮物是置于导磁体正下方两个不同重量的铁球,伺服电机驱动盘状永磁铁旋转,改变通过悬浮物的有效磁通量,进而控制悬浮力大小,实现两铁球的稳定悬浮。根据系统结构及可控磁路式并联型永磁悬浮原理将系统模型简化,并建立系统的数学模型,分析使系统稳定悬浮的可能性,计算使系统稳定悬浮的PD控制器反馈增益范围。实验结果表明:在控制器参数满足计算范围条件下,当给系统一较小阶跃外扰时,在实时控制系统作用下,系统在很短的响应时间内可达到新的稳定悬浮状态;相同的外扰可导致左右球异向的位移响应结果,左球移动方向与外扰相同,而右球相反。     

永磁悬浮无尘传送系统的悬浮特性及解耦控制仿真分析

介绍了一种永磁悬浮无尘传送系统。该系统采用两对双列对称布置的非接触主动永磁悬浮支承。悬浮支承中,永磁铁提供磁性力,伺服电机驱动永磁铁转动,通过改变悬浮支承与悬浮导轨间的磁通量实现悬浮力的实时控制。通过消除冗余的悬浮支承控制点建立悬浮系统的动力学模型,应用LQR控制方法仿真分析未解耦系统的悬浮特性,证明该系统的耦合性及不易控制性。此外,采用状态反馈解耦控制策略对系统进行解耦控制仿真,结果表明该策略可以使系统解耦,并具有较高的稳定性和较快的响应特性。     

永磁悬浮技术的实现机理与发展现状

永磁悬浮技术利用磁体与磁体或铁磁体之间力的作用实现无接触支撑,具有无摩擦、低能耗等显著特点。随着稀土永磁材料的发展,具有高剩磁、高矫顽力、高磁能积的永磁体大幅提高了系统的承载性能,国内外学者相继开展了永磁悬浮技术的研究工作。我国的稀土储量居世界首位,发展永磁悬浮技术具有天然优势和重要意义。首先,明晰了永磁悬浮技术的机理和特点;其次,系统性回顾了永磁被动悬浮和永磁主动悬浮技术的发展历史,并重点阐述了气隙调节式、磁阻调制式、磁源调整式三种永磁主动悬浮系统的磁路结构、悬浮特性及研究现状;再次,分析了磁路设计与优化、磁力精确建模、系统性能与控制方法等技术难点,并提出相应的解决策略;最后,展望了永磁悬浮技术在重力补偿器、轻载微型轴承、低频隔振等领域的未来应用前景及发展趋势。     

永磁悬浮非接触回转驱动系统

提出一种永磁悬浮非接触回转驱动系统,该系统由悬浮部分和非接触回转驱动两部分构成。悬浮部分采用运动控制方式,利用音圈电动机驱动永磁铁实现悬浮物竖直方向的稳定悬浮;回转驱动部分由直流伺服电动机驱动径向磁化永磁铁回转,形成变化磁场,非接触驱动悬浮物回转。本系统未在悬浮物中加入任何磁性材料,仅利用悬浮物表面剩余磁化点实现悬浮物的非接触回转驱动。介绍系统的悬浮与驱动原理,建立非接触驱动数学模型,并利用仿真与试验分析系统的回转驱动特性。分析结果表明：悬浮物的非接触回转驱动可以由伺服电动机驱动盘状永磁铁旋转来实现。铁球是否旋转与磁铁的数量无关;驱动磁铁的数量与系统的响应速度成正比,驱动磁铁的数量增多,输入速度和输出速度之间的线性度相对提高,旋转稳定。明晰本系统的非接触驱动特性,为隔离环境下铁磁性物品或零件的非接触操纵和姿态控制奠定了理论基础。     

永磁铁研磨实验装置磁路的计算分析

用永磁铁组成磁路,制作成磁力研磨实验装置,可用于零件的研磨或抛光加工,且永磁铁制作的研磨装置有许多优点。文中介绍磁路结构及技术参数,用磁导法及漏磁系数法计算永磁铁磁路,并确定磁路结构的几何尺寸等。     

基于Ansoft的永磁悬浮直线导轨平台的设计及磁力分析

提出了2种永磁悬浮直线导轨平台的方案,然后利用Ansoft Maxwell电磁场有限元分析软件进行了平台承载能力和刚度的计算分析,通过数据对比得出结论:4磁条方案适用于重载低刚度场合,8磁条方案适用于轻载高刚度场合;永磁悬浮的移动平台在不同位置时,承载方向上的磁力基本无变化,沿运动方向上的磁力却有明显变化。     

加工中心龙门磁悬浮高度的滑模控制

针对龙门加工中心中的移动横梁,提出了采用磁悬浮技术,实现无摩擦驱动的新型控制方案。根据所建立的横梁磁悬浮系统的数学模型,应用基于微分几何的反馈线性化方法将非线性的电磁悬浮系统转化为线性系统,然后利用积分滑模控制器来对整个系统进行鲁棒控制。仿真研究结果表明,与传统控制方法相比,系统具有很强的抗扰性和较高的刚度,横梁能够实现无摩擦稳定悬浮。     

保护轴承结构对垂直轴磁悬浮风力机主轴跌落轨迹的影响

以垂直轴磁悬浮风力机的支撑结构为研究对象,运用ADAMS机械系统动力学仿真软件。在对磁悬浮主轴结构各部件间的接触关系分析的基础上,建立垂直轴磁悬浮风力机主轴结构跌落仿真模型。通过建立3种不同磁悬浮主轴中保护轴承的结构模型,并对3种不同结构建立主轴跌落轨迹的运动方程;运用ADAMS进行跌落过程仿真,得出主轴跌落过程的运动曲线。主要对比了主轴在轴向方向的运动轨迹,直观的展现出保护轴承结构的不同对磁悬浮主轴跌落过程中的运动轨迹的影响,为研究垂直轴跌落分析,以及对磁悬浮支承结构的保护装置的改进与优化提供了理论参考依据。     

数控机床用磁悬浮系统非线性时变滑模变结构控制

为实现数控机床横梁磁悬浮系统悬浮气隙的精确控制,采用了非线性时变滑模变结构控制策略。首先,通过设计一种带有指数项的滑模面,使系统在任意初始状态下的状态变量都直接处于系统的滑模面上,实现对参数摄动和外部干扰的全局鲁棒性;然后,在此基础上设计了一种时变滑模控制器,并通过李亚普诺夫定理证明了该控制律的稳定性。仿真实验结果表明,非线性时变滑模变结构控制方法在保证系统全局稳定的前提下提高了滑模面的收敛速度,有效地削弱了抖振。     

磁悬浮球系统控制器的分析设计

从磁悬浮球的物理模型出发,建立了磁悬浮球系统的线性化数学模型,在模型分析的基础上,对控制策略进行了分析与研究.重点介绍了通过积分分离和微分先行两种方法对PID控制器进行优化设计的方案.仿真研究表明,所设计的控制器较好地满足了系统的要求.     

Design, implementation, and testing of a single axis levitation system for the suspension of a platform

This paper describes the design and implementation of a single axis DC attraction type suspension system, where a platform (vehicle structure) of around 14 kg mass is made to remain suspended at the desired operating gap under a ferromagnetic guide-way. The prototype has four electromagnetic actuators of attraction type and four inductive gap sensors, all located at the corners of the platform. The four actuators are controlled independently through four identical controllers, and the stable levitation of the platform is achieved through the single input and single output (SISO) control of each air-gap. The emphasis of this work is on the design and development of the switched mode power amplifier cum controller unit for the four actuators. The proposed single switch-based power circuit simplifies the overall hardware, and it can be extended to any number of magnet-coils. A cascade lead compensation control scheme utilizing an inner current loop and outer position loop has been designed and implemented for the stabilization of such a highly unstable and strongly nonlinear system. The prototype has been successfully tested, and stable levitation was demonstrated with the desired operating gap.     

基于遗传算法的可控励磁直线磁悬浮同步电动机自抗扰控制

对可控励磁直线磁悬浮电动机控制系统提出基于遗传算法的自抗扰控制策略。根据可控励磁直线磁悬浮电动机的运行机理,建立其数学模型。设计反馈跟踪微分器、扩张状态观测器、非线性反馈控制律,对传统函数fal进行改进,应用到控制器中。实现对给定信号的跟踪,并将系统耦合量和外界扰动作为系统的“总扰动”,并对总扰动进行观测与补偿。针对控制器中存在多个参数难以整定的问题,采用遗传算法对控制器参数进行寻优。对控制系统进行仿真研究,结果表明,基于遗传算法的自抗扰控制系统具有对参考信号良好的跟踪性能,以及对干扰信号的抑制能力。     

可辅助制动永磁变速器的设计与研究

永磁变速器与永磁缓速器结构相似原理相同,为使两者的功能在同一机械上实现,提出了一种可辅助制动的永磁变速器新结构,推导了永磁变速器的磁转矩方程,结合MATLAB探究了变速器的耦合、变速及辅助制动能力。结果显示磁转矩受永磁体磁极对数、永磁体厚度、磁阻等因素的影响,变速时的转速差越小,效率越高,制动时的减速度受从动盘初始转速的影响且最大可达9m/s2。最后通过ANSYS软件分析了主从动盘的变形情况,论证了可辅助制动永磁变速器的可行性。     

Image-based fall detection and classification of a user with a walking support system

The classification of visual human action is important in the development of systems that interact with humans. This study investigates an image-based classification of the human state while using a walking support system to improve the safety and dependability of these systems.We categorize the possible human behavior while utilizing a walker robot into eight states (i.e., sitting, standing, walking, and five falling types), and propose two different methods, namely, normal distribution and hidden Markov models (HMMs), to detect and recognize these states. The visual feature for the state classification is the centroid position of the upper body, which is extracted from the user’s depth images. The first method shows that the centroid position follows a normal distribution while walking, which can be adopted to detect any non-walking state. The second method implements HMMs to detect and recognize these states. We then measure and compare the performance of both methods. The classification results are employed to control the motion of a passive-type walker (called “RT Walker”) by activating its brakes in non-walking states. Thus, the system can be used for sit/stand support and fall prevention. The experiments are performed with four subjects, including an experienced physiotherapist. Results show that the algorithm can be adapted to the new user’s motion pattern within 40 s, with a fall detection rate of 96.25% and state classification rate of 81.0%. The proposed method can be implemented to other abnormality detection/classification applications that employ depth image-sensing devices.     

Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.     

Instrumentation and control of a two-stage 4-bed silica gel + water adsorption cooling cum desalination system

This paper presents the instrumentation and control architecture for a laboratory based two-stage 4-bed silica gel + water adsorption system. The system consists of primarily two fluids: refrigerant (water vapour) and heat transfer fluid (water) flowing through various components. Heat input to the system is simulated using multiple heaters and ambient air is used as the heat sink. The laboratory setup incorporates a real time National Instruments (NI) controller to control several digital and analog valves, heaters, pumps and fans along with simultaneous data acquisition from various flow, pressure and temperature sensors. The paper also presents in detail the various automated and manual tasks required for successful operation of the system. Finally the system pressure and temperature dynamics are reported and its performance evaluated for various cycle times.     

永磁同步电机控制系统的建模与仿真分析

在建立了永磁同步电机数学模型的基础之上,仿真模型中包含了建立三相电流源型逆变器模块、DQ向ABC转换模块等,并改进了电流滞环控制模块。文中提出了一种分析永磁同步电机（PMSM）的新方法,分析了伺服系统在不同给定速度下的表现稳定性以及转矩电流的变化等。     

高精度智能相机光电跟踪控制系统的研制

主要研究空间光通信中光束抖动的跟踪控制,建立了以可开窗口高帧频CMOS相机和大规模FPGA芯片为核心的全功能camera link光束跟踪控制硬件平台.并在FPGA芯片中嵌入实现了全部跟踪控制算法,包括图像处理中将二元线性插值结合重心算法实现光斑的高精度定位,以及流水线并行运算的模糊增益自调整PID跟踪控制的状态机等.实验结果表明系统实时性强,算法的时间开销很小,光斑的定位精度高,跟踪带宽达到200 Hz以上,低频时跟踪精度约为2 μrad,实现了光束抖动的高带宽高精度的跟踪控制.