【作者】 王金鹏；

【导师】 赵淳生；

【作者基本信息】 南京航空航天大学 ， 机械设计及理论， 2013， 博士

【摘要】 精密运动平台在显微外科手术设备、电子隧道扫描显微镜、三坐标测量机等很多精密设备上都有着广泛的应用需求。利用压电陶瓷的逆压电效应工作的超声电机以其响应快、分辨率高等独特的性能愈来愈得到精密驱动领域专家学者的重视和认可。目前，利用压电陶瓷的静变形来实现纳米级定位精度的运动平台，其行程往往只有几十到几百微米，而利用电磁电机和压电作动器组合而成的宏微结合运动平台又有着机械结构和控制系统复杂的缺点，因此，由具有纳米级位移分辨率的超声电机构建大行程、高精度运动平台成为前沿技术之一。本文的主要工作围绕着超声电机驱动的大行程、高精度运动平台的关键技术，进行了深入的研究，并取得以下成果：（1）研究了行波型旋转超声电机的单周速度波动率、步距一致性的问题，提出了一种提高单周速度稳定性的结构改进方案。理论分析认为加工和装配误差引起的定/转子接触界面上沿圆周方向的压力不均衡是影响行波型旋转超声电机单周速度稳定性、步距均匀性的主要原因之一。为此，提出一种单轴承支撑附加调心结构的方案，可以使接触界面实现压力自平衡，改善接触界面的压力分布。实验结果表明，空载单周相对速度波动率降低了约40.0%，波动小于2.0%；这有利于提高运动平台开环步进运动时步距的一致性。（2）研究了行波型旋转超声电机的最小响应脉冲宽度和电机关断时过冲量的大小。旋转超声电机的启动/停止瞬态特性决定了其角度分辨率，进而影响丝杠平台的位移分辨率（最小步距），影响运动平台的定位精度。结合丝杠导程（4mm），研究结果可以预测出超声电机驱动的丝杠平台理论上所能达到的定位精度（0.6μm）。（3）开发了行波型旋转超声电机驱动的二维平台。利用直线光栅尺和编码器两种不同的位置反馈单元的信号作比对，分别测试了平台的螺距不均匀误差、回程误差，并在搭建的基于GT-400运动控制卡的控制系统中对其进行了补偿，将丝杠平台的定位精度由丝杠的标称定位精度±5μm提高至±2.5μm。（4）直线超声电机驱动的运动平台的性能很大程度上取决于直线超声电机的性能，而直线超声电机的性能很大程度上取决于其定子与动子（平台）的接触状态，而为了减小接触变形对定位精度的影响，本文采用高硬度摩擦材料（ZrO、AL2O3）作为摩擦副。因此，作者研究了高硬度材料摩擦副直线超声电机定子与动子之间的接触匹配问题，提出了“接触频率”的概念。通过建立高硬度摩擦副直线超声电机的定子/动子在接触面法向上的接触模型并进行理论和实验研究，得出了定子支撑弹簧刚度、预压力、定子质心和驱动足的振幅等对接触频率的影响规律，探讨了相关改善方法。（5）为了提高运动平台的驱动单元的性能，研究了提高直线超声电机驱动单元的推力、效率及稳定性的途径。提出采用多个超声电机协同工作的“异步并联”的方法。通过设定每个超声电机的驱动信号之间的相位，使得不同的超声电机定子依次交替作用于动子，以避免多个定子间相互干扰、磨损加剧和内耗增加的问题，提高了驱动单元的驱动效率，并进行了实验验证。（6）直线电机驱动的运动平台的位移分辨率、瞬态特性决定了直线平台的定位精度；作者研究了单足V形、双足碟形直线超声电机的瞬态特性及双足蝶形直线超声电机驱动的运动平台的位移分辨率，分析了各种参数对位移分辨率的影响。实验结果表明：定子从开始振动至达到稳定振幅仅需1.7ms，关断时间小于1ms；本文双足直线超声电机驱动的精密运动平台的分辨率达到25nm。（7）建立了直线超声电机驱动的运动平台的等效电路模型，得到了其传递函数。分析比较了基于MSP430单片机、DSP以及GT-400运动控制卡的各种控制器的特点，并在基于GT-400运动控制卡的控制系统上实验了模糊与PID双模控制算法，使运动平台的精度在60mm行程范围内达到了±0.5μm。更多还原

【Abstract】 There are broad needs for the precision motion stage in various fields, such as micro surgeryequipment, the electron scanning tunneling microscope, the three coordinate measuring machines, etc.Ultrasonic motor (USM) which utilizes the inverse piezoelectric effect of the piezoelectric material,has got more and more attention from the experts and scholars working in the precision driving fieldsfor its advantages like fast response, high resolution, etc. The travel range of piezoelectric stage usedthe static deformation of piezoelectric ceramics always be only get to a few hundred microns. On theother hand, the actual applications of macro/micro combined stage have been restricted in thecomplex structure and controller. As a result, the research of the large travel precision motion stagedriven by USM is becomeing one of the frontier technologies.The main work in this paper focus on some key aspects of the precision motion stage driven byUSM with a large travel:（1） In this paper, the author studied the velocity fluctuation ratio in each cycle and the steppitch consistency of traveling wave type rotary ultrasonic motors (TRUM) and proposed a structuralimprovement scheme. The analysis results show that one of the main reasons for velocity fluctuationof TRUM is pressure imbalance along the circumference on the contact interface because ofmachining or assembling error in the present case of duplex bearing structure. Theoretical analysisshows that the scheme can realize pressure auto-balance with single bearing and self-aligningstructure. It also can make the pressure distribution on contact interface more uniform. Experimentalresults show that the no-load velocity fluctuation ratio decreased40.0%, and velocity fluctuationrange less than2.0%. This will help improve the consistency of the step pitch when the stage isworking in the open loop stepping mode.（2）The minimum pulse width which can drive TRUM and the amount of overshoot pulseswhen the TRUM is power off were studied in this paper. They are closely related to the TRUM’stransient characteristics. The angular resolution of TRUM is determined by its transient characteristics.Meanwhile, the displacement resolution of the stage driven by TRUM is determined by the angular resolution of TRUM. This research can forecast the positioning accuracy of the ball-screw-drivenstage if the screw lead was given.（3）One2-DOF stage driven by TRUM was developed in this paper. The lead-screw pitch errorand the return error were studied through setup two sets of position feedback systems with linearencoders and rotary encoders. Finally, the verification experiment has been accomplished on the stage.Experimental results show that the positioning accuracy of the stage has been improved to2.5μm bythe control system based on GT-400motion control card with error compensation.（4）The performance of the stage driven by linear ultrasonic motors (LUSM) is determined bythe performance of LUSM. The performance of LUSM depends on the contact state on the contactinterface. Therefore, the contact problem of linear ultrasonic motor was studied in this paper. Hardcontact materials, such as ZrO or AL2O3, have been used to reduce the impact of contact deformationand surface roughness. However, experimental results show that, in this kind of hard contact materialslinear ultrasonic motors (HLUSM), there exists a phenomenon that the contact frequency betweenthe stator and the mover (slider) is far less than the frequency of the driving signal, which prevents thevibration energy of the stator from being utilized fully. In order to solve this problem, we have madethe model of the high frequency micro-amplitude contact behavior in normal direction of HLUSM.Then, theoretical analysis and experimental investigation on micro-impact processes of HLUSM havebeen finished. The impact laws of parameters on the contact frequency have been derived, includingthe stiffness of the stator supporting spring, preload and the high frequency vibration amplitude of thedriving tip and the low-frequency vibration amplitude of stator. Finally, the related improvementmeasures have been discussed.（5）Aim at improving the performance of driving units of motion stage, the asynchronousbundle of linear ultrasonic motor (ABLUSM) which can build the high thrust, high efficiency, stableand reliable driving unit with LUSM has been discussed. The concept of ABLUSM is proposed. Thebasic principle is that numbers of stators (vibrators) alternately drive a mover (rotor) in a drivingsignal cycle, so that, it can avoid the problem of mutual interference of different stators, wear andinternal power dissipation increased. Therefore, the efficiency of the driving unit can be improvedsignificantly. Finally, the verification experiment was conducted.（6）The positioning accuracy of the stage driven by LUSM is largely depends on thedisplacement resolution and the transient characteristics of the LUSM. So, the transient characteristicsof two kinds of USMs have been studied in this paper. Furthermore, theoretical analysis andexperimental investigation on the resolution of the stage driven by the HLUSM with two driving tips have been completed. The impact of various parameters on the displacement resolution of the stagewas also discussed. Experimental results show that, the displacement resolution of the precision stagedriven by HLUSM with two driving tips reached25nm.（7） The equivalent circuit model of motion stage driven by HLUSM was established, and thetransfer function of this model was derived. The characteristics of controllers which based on MCU,DSP and GT-400motion control card have been compared with, respectively. One experiment usedfuzzy and PID dual-mode control algorithm has been finished on the control system based on GT-400motion control card. Experimental results show that the positioning accuracy of the stage has beenimproved to0.5μm with the travel of60mm.更多还原