1、科学仪器评论 80，085104(2009)简单紧凑的大步长线性压电步进电机Qi Wang1 and Qingyou Lu1,2,a)1 合肥微物质科学国家实验室，中国科学技术大学，安徽合肥 230026，中华人民共和国2强磁场实验室，中国科学院，安徽合肥 230031，中华人民共和国的中国(2009.6.11 接收；2009.7.16通过；2009.8.14 网络出版)我们提出一篇关于新型压电步进电机的文章，它具有高密度，刚性，简单，和任意方向可操作性的特点。虽然测试在室温下进行，但是由于宽松的操作条件和大步长，该电机也能在低温下工作。电机由一个压电扫描器管来运行，它的轴向几乎被切成两半，通
2、过轴的弹簧部分夹持一个空心轴内部两端。双驱动电压仅使压力管的两部分在一个方向上变形，且能反向移动轴承以恢复原状，反之亦然。美国物理研究所工业部: 10.1063/1.3197381一 简介扫描探针显微镜（SPM）在一些有重要类型的原子甚至是亚原子研究的纳米技术领域是一个功能强大的工具。显微镜的一个关键组成部分，就是它那个能在纳米范围内粗略接近被测物的末端或者样品的定位器，这多半需要一个压电步进电机。 1-11压电电动机在其他领域也有重要应用，例如显微镜在现代光学 12，细胞或者 DNA控制中的定位 13。到现在为止，在尺蠖 3,14-19、甲虫类生物 5-7,10,20-22、剪切压电步进电机
3、 2,8,9,11,23,24，惯性滑块4,25-28等文献中找到了各种各样的压电电动机。然而，他们都有着严重的缺点。对于前三种而言，每一种都需要三个或者更多的电压驱动才能被操作，这使得电机的结构和控制都变得太过复杂。在小领域（极端环境条件）或者微信号测量等方面，他们的可靠性和应用程度成为了一个很大的问题。惯性滑块虽然简单，但是特性不够硬（容易产生振动，从而降低了原子图像的品质） ，并且无法产生足够的推动力。在这片文章中，我们阐述了一个不具有以上限制的压电电动机。电机由一个压电扫描器管（PST）来运行，它的轴向几乎被切成两半，通过轴上的弹簧部分夹持一个空心管（HS）内部两端。双驱动电压仅使压力
4、管的两部分在一个方向上变形，且能反向移动轴承以恢复原状，反之亦然。其紧凑，简单，刚度，和大步长的特性使其在小空间（极端条件下）和低温应用中非常有用。a)作者的联系方式如下。电话：86-551-360-0247。 电子邮箱： 。二 设计原理图 1为我们设计的原理图。图 2为实物图。两个 1.5mm厚的蓝色环粘（采用了来自环氧树脂技术的环氧树脂）在了 7.9mm内径、10.2mm 外径的压电扫描管（压电扫描管物理模型 130.24，长30mm，外径 10mm，壁厚 0.5mm，有200V 的最大工作电压）的整个外环边缘处。在压电扫描管的外径蓝色环上切两个相对的切口，长度从一段的蓝色环到另一端的蓝色
5、环，总长大概占到整个压电扫描管的 92%的长度。为被切到的蓝色环是粘在基环上的，另外一个蓝色环被切成了两半，它被称作半夹持环（夹持一个可转动的空心管） 。没对没有被切割的相邻电极用导线连在了一起，形成两个半圆柱形电极，任意一个称为电极 1（E1） ，为了方便，把另一个称为电极 2（E2） 。由 E1和 E2控制的压电扫描管的两部分分别简称为 P1，P2。电机可移动部分是一个钛合金空心管，它被插入到压电扫描管的内部，如图 1（a）所示。我们还研究过圆形和方形的空心管，如图 1（b）所示。对于圆形空心管而言（长 45mm，内径5.8mm，外径 7.8mm，穿过蓝色环到达压电扫描管的边缘并形成一个
6、0.05mm的间隙） ，导线从与他垂直的平面的一段管过轴到另一端。两个切割线不会穿过整个空心管，会在每端留下 0.8mm的未切割部分。空心管切除部分的那对空隙朝同一方向打开，并且和压电扫描管上分布的缝隙是同一方向。一个弹性很强的弹簧被牢固的固定在空心管的一端，推动空心管的打开，分别对夹持的半环施加N1和 N2的推力，同时空心管另一端一个较弱的压缩弹簧让空心管给基换施加一个总的压力Nbr。N 1，N 2和 Nbr在上述较强和较弱的压缩弹簧上能大致平衡。因此，只要两者的摩擦系数相等，那么施加在空心管的最大静摩擦力会因为这三个压力的大致相等而抵消（方向可能与下面讨论的相反） 。图 1（a）我们的压电
7、电机的结构（b）两种空心管的研究这种在压电扫描管和空心管两段互相夹持的结构有一个很大的好处，就是这种结构很稳定（耐振动噪声） ，能在任意方向上安装。同时也应注意到，这种夹持结构是灵活的（大范围的力） ，这表明较大的温度变化不会引起夹持力显著的变化，且这三个最大静摩擦力任然可以保持平衡。为了能控制电机，图 3（a）所示的两个驱动电压 D1和 D2分别适用于压电扫描管的电极 E1和E2（内部电极电压定为-200V） ，这能试相对的半圆形螺线管 P1和 P2变形，如下图所示。在第一个1/6周期（T1）内，P1 和 P2初始化状态。在 T2内，P1 保持不变，P2 收缩。这会导致 P2和空心管的自由端
8、的电压下降，而不是基环和空心环指间电压的下滑，因为 P2到空心管的最大静摩擦力小于 fr2小于 P1到空心管与基环到空心管的最大静摩擦力之和，f r1+frbr（假设这些摩擦力远远小于P1和 P2的阻力 Fbl1和 Fbl2） 。下一时间段，T3，P1 和 P2保持在之前的状态。这种纯粹的“等待”是为下一步的同步做好准备，这不是必须的，可以去掉来节省时间。在 T4时间内，P1 收缩，P2 保持不变。这会导致 P1和空心管的自由端电压下降（与 T2时间的动作原因一样） 。到现在为止，P1和 P2都已经在基于基础环，没有移动空心管的情况下从扩张的状态变到收缩的状态。T5 是另外一个等待时间，它也是
9、可以去掉的。在最后一个 1/6周期（T6）内，P1 和 P2同时扩张。这次仅在基础环和空心环之间的电压发生了下滑，因为 frbrNbr以使空心管运动，这就意味着 LBLC这个条件应该满足。因为如果 LC=0，空心管不能运动，那么运动范围最终由 0Nbr for the HS to walk, this means that LBLC should be satised. Since the HS cannot move if LC=0, the range of motion is nally determined by 0LCLB. In our design, LC+LB30mm(the
10、length of the PST), we expect that maximum displacement of the square HS is less than 15 mm. This issue of limitation on the range of motion can nevertheless be solved if the clamping springs are attached to the sapphire rings(not to the HS).III. PERFORMANCE TESTWe have tested the room temperature p
11、erformance of the motor in two extreme cases of moving directions(upward and downward)by measuring its step size and speed as functions of the frequency Figs. 5(a)and 6(a)for circular and square HS, respectivelyand operating voltageFigs.5(b)and 6(b)for circular and square HS, respectively. The press
12、ing forces were set to N1N 2N br0.22N for circular HS which are much smaller than the blocking forces (Fbl1F bl22N)of the driving piezo-P1 and P2.The maximum step size is 12.9 m with the measurement conditions being: circular HS, downward stepping with 0.3 Hz driving frequency. When the moving direc
13、tion is changed to upward, the step size becomes 11.7 m due to gravity. In case of square HS, the downward and upward step sizes are 8.9 and 8.2m, respectively, which is more uniform because of its knife edge contacts with the sapphire rings. All these step sizes are rather large compared with other
14、 types of piezoelectric motors9,11,23 with the similar size.The speed of motion is of course closely related to the driving frequency. The maximum driving frequency we set was 50 Hz, at which the speeds for the circular(upward versus downward) and square(upward versus downward)HS were:(22.27 versus
15、24.62)and(19.44 versus 19.98)mm/min.When the driving frequency increases or if the magnitude of the operating voltage drops, the step size diminishes as seen in Figs. 5 and 6. Although we get larger step size from circular HS, we still prefer the square HS owing to its advantages listed earlier. For
16、 instance, the travel range using the square HS is 9 mm(as designed)compared with 3.3 mm for the circular HS(worse than the designed 6.6mm travel range).The performance curves of the square HS motor seen in Fig.6 are also smoother and more consistent than those (Fig.5)of the circular HS motor.FIG.5.
17、The step size(left vertical axis)nd speed(right vertical axis of the motor using the circular HS as functions of (a) frequency(maximum operating voltage=200 V) and (b) maximum operating voltage (frequency=20 Hz).Although tested in room temperature, the motor has high potential to work in liquid heli
18、um temperature for two reasons:(1)its large step size can afford to pay for the thermal contraction still with remarkable step size remaining to produce a move;(2)its spring clamping structure validates the required friction relationship,|fr1|fr 2|fr br|,in a very wide temperature range since a chan
19、ge from room temperature to liquid helium only shrinks the compression springs (5 mm long, spring constant is about 286 N/m)by microns which do not considerably affect the pressing forces between the HS and the sapphire rings.The square HS may suffer wear and tear issues as its four edges could be s
20、cratched by the sapphire rings. To test its durability, we operated the motor repeatedly with 200 V and 50 Hz driving voltages for more than one thousand times with a displacement about 3 mm and the motor still worked well. The wear was not severe. Of course, the HS can be coated with wear resistant
21、 materials for better protection if necessary.FIG.6.The step size(left vertical axis)nd speed(right vertical axis of the motor using the circular HS as functions of (a) frequency(maximum operating voltage=200 V) and (b) maximum operating voltage(frequency=20Hz).IV. CONCLUSIONWe have presented a powe
22、rful linear piezoelectric motor that owns several important features not simultaneously owned by other piezomotors,including: large step size,small size,very rigid,simple in structure and operation, very large temperature range, easy to make and loose machining tolerance,etc. Its durability has also
23、 been tested,which is rather good.All these are highly desired in the construction of a modern SPM.ACKNOWLEDGMENTSThis work was supported by the National Natural Science Foundation of China under Grant No.10627403,the project of Chinese national high magnetic eld facilities,and Science Foundation of
24、 The Chinese Academy of Sciences under Grant No. YZ200846.1B.J.Albers,M.Liebmann,T.C.Schwendemann,M.Z.Baykara,M.Heyde,M.Salmeron,E.I.Altman,and U.D.Schwarz,Rev.Sci.Instrum.79,033704 2008.2Chr.Wittneven,R.Dombrowski,S.H.Pan,and R.Wiesendanger,Rev.Sci.Instrum.68,3806 1997.3R.A.Wolkow,Rev.Sci.Instrum.6
25、3,4049 1992.4Y.Hou,J.Wang,and Q.Lu,Rev.Sci.Instrum.79,113707 2008.5T.H.Chang,C.H.Yang,M.J.Yang,and J.B.Dottellis,Rev.Sci.Instrum.72,2989 2001 .6J.H.Ferris,J.G.Kushmerick,J.A.Johnson,M.G.Yoshikawa Young quist,R.B.Kessinger, H.F.Kingsbury,and P.S.Weisse,Rev.Sci.Instrum.69,2691 1998.7N.Pertaya,K.-F.Bra
26、un,and K.-H.Rieder,Rev.Sci.Instrum.75,26082004.8T.Hanaguri,J.Phys.:Conf.Ser.51,514 2006.9S.H.Pan,E.W.Hudson,and J.C.Davis,Rev.Sci.Instrum.70,14591999.10L.A.Silva,Rev.Sci.Instrum.68,1300 1997.11A.K.Gupta and K.-W.Ng,Rev.Sci.Instrum.72,3552 2001.12J.Lee,J.Chae,C.K.Kim,H.Kim,S.Oh,and Y.Kuk,Rev.Sci.Inst
27、rum.76,093701 2005.13J.Kusch,A.Meyer,M.P.Snyder,and Y.Barral,Genes Dev.16,16272002.14Burleigh Instruments,Inc.,U.S.Patent No.3,902,084 1975.15P.E.Tenzer and R.Ben Mrad,IEEE/ASME Trans.Mechatron.9,4272004.16J.Frank,G.H.Koopmann,W.Chen,and G.A.Lesieutre,Proc.SPIE3668,717 1999 .17J.Ni and Z.Zhu,IEEE/AS
28、ME Trans.Mechatron.5,441 2000.18K.Duong and E.Garcia,Proc.SPIE 2443,782 1995.19J.E.Miesner and J.P.Teter,Proc.SPIE 2190,520 1994.20B.Koc,S.Cagatay,and K.Uchino,IEEE Trans.Ultrason.Ferroelectr.Freq.Control49, 495 2002.21M.Bexell and S.Johansson,Sens.Actuators,A 75,118 1999.22J.Frohn,J.F.Wolf,K.Besock
29、e,and M.Teske,Rev.Sci.Instrum.60,1200 1989.23M.H.Arafa,O.J.Aldraihem,and A.M.Baz,IEEE Proceedings of the Fifth International Symposium on Mechatronics and Its Applications,2008 unpublished, pp.15.24S.H.Pan,International Patent Publication No. WO 93/19494 1993.25R.Yoshida,Y.Okamoto,and H.Okada,J.Jpn.Soc.Precision.Eng.68,536 2002.26W.Zesch,R.Buchi,A.Codourey,and R.Siegwart,Proc.SPIE 2593,801995.27D.-S.Paik,K.-H.Yoo,C.-Y.Kang,B.-H.Cho,S.Nam,and S.-J.Yoon,J.Electroceram.22, 346 2009.28L.Howald,H.Rudin,and H.-J.Gijntherodt,Rev.Sci.Instrum.63,39091992.
