单片机步进电机控制系统外文文献翻译

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：qxl@https://www.360docs.net/doc/9c17121197.html,。

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N br。N1，N2和N br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+fr br（假设这些摩擦力远远小于

P1和P2的阻力F bl1和F bl2）。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fr br

图2 压电电机的实物图

除了上述讨论的原型空心管，我们也尝试了方形空心管（42mm长，5.6mm宽，壁厚0.7mm），它的壁从一段到另一端进行了线切割（切割长度35mm），与另一个切割线互相平行，组成了一个蛇形的结构，如图1（b）所示。切割平面之间的距离是0.8mm。这种设计比圆形的设计相对以下方面要好：（1）空心管在蓝环上的滑落就想溜冰鞋在冰上的滑行，允许更大的压力（更线性）却又不会有更多的阻力；（2）阻力值更精确，更稳定；（3）只需要一个压力弹簧，它在方形空心管的位置能满足最佳的工作条件fr1≈fr2≈fr br；（4）方形空心管和蓝色环指间的最小空隙容易调整扭曲（较小的空隙容易形成较大的运行距离）。

图3（a）趋势空心管朝压电扫描管方向扩张的两个驱动电压（b）趋势空心管朝压电扫描管相反方向扩张

的两个驱动电压

显然的，夹持力N1，N2和Nbr在空心管运动时不是一直存在的，因此需要限制它的运动范围。方形空心管的运动范围可以从下述方式获得。在图4中，弹簧产生的理Fs，LB和LC分别代表从弹簧到基环，从弹簧到半圆形夹持环的距离，由杠杆原理可知：

L B·F s=(N1+N2)·(L C+L B),L C·F s=N br·(L C+L B)。因为N1≈N2，我们要求N1+N2>N br以使空心管运动，这就意味着LB>LC这个条件应该满足。因为如果L C=0，空心管不能运动，那么运动范围最终由0

以解决的。

图4 图示可得运动范围大小

三．性能测试

我们在室温下，在移动方向（向上移动和向下移动）的极端条件下测试了电机的运行情况，包括它的步长，速度，工作频率[分别如图5（a）的原型空心管和图6（a）的方形空心管]，工作电压[分别如图5（b）的原型空心管和图6（b）的方形空心管]。圆形空心管的压力值设为N1≈N2≈N br≈0.22N，这个值远远小于驱动压电P1和P2的阻力值（F bl1～F bl2～2N）。

最大步长是12.9μm，测试条件是：0.3Hz向下滑的驱动频率带动的圆形空心管。当移动方向变为向上的时候，步长因为重力变为11.7μm。如果是方形空心管，向下的步长和向上的步长分别是8.9μm和8.2μm，这个值更为合适，因为他的切割边缘与蓝色环相接。所有这些步长值都比其他类似大小的压电电机9,11,23的步长要大。电机的转速当然和驱动频率很接近。我们设置的最大驱动频率是50Hz，圆形空心管（向上运行对向下运行）和方形空心管（向上运行对向下运行）的转速分别是（22.27对24.62）（19.44对19.8）mm/min。

当驱动频率上升或者工作电压值下降的时候，步长的下降情况如图5和图6所示。虽然我们从圆形空心管中获得了较大的步长，但是我们更倾向于使用方形空心管，因为它的优点限制更少。例如，方形空心管的运行范围是9mm（理论上），而圆形空心管的运行范围是3.3mm（比方形的在理论上少了6.6mm）。方形空心管电机的运行曲线如图6所示，比圆形空心管电机的曲线更平滑更稳定。

虽然测试是在室温条件下进行的，但是电机在固化氮的温度下工作也有很大潜力，原因有两个：大步长的特性可以应对热量下降带来的问题，保持运行的稳定；（2）它的弹簧夹持结构可以让压力弹簧（～5mm长，劲度系数大约是286N/m）在从室温到固化氮的很大的温度范围变化下仅有微米级的下滑，确保必要的摩擦力关系的成立，|fr1|≈|fr2|≈|fr br|,这种变化对于空心管和蓝色环之间的压力值的影响可以忽略不计。

方形空心管可以承受磨损和撕裂的问题，因为它的四个边缘可以被蓝色环固定。为了测试它的耐久度，我们在±200V和50Hz的驱动电压下超过一千次的3mm的替换条件下操作电机，电机任然能正常工作。磨损不严重。当然，空心管外部可以加上耐磨金属材料进行更好的保护（如果需要的话）。

200V）（b）最大工作电压（频率=20Hz）

图6 用圆形空心管测试的电机步长（左侧垂直轴）和速度（右侧垂直轴）（a）频率（最大工作电压=±

200V）（b）最大工作电压（频率=20Hz）

四．结束语

我们呈现了一个强大的线性压电电动机，它拥有其他压电电动机不能同时具有的几个重要特性，

包括：大步长，小尺寸，刚性，结构简单，操作方便，温度范围大，易形成不精确的加工公差等。耐久度测试结果非常好。在建设一个现代化的扫描探针显微镜中，所有这些性能都是非常需要的。致谢

这项工程得到了中国国家自然科学基金10627403号，中国国家强磁场设施计划和中国科学院自然科学基金YZ200846的资助。

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REVIEW OF SCIENTIFIC INSTRUMENTS 80, 085104 2009

A simple, compact, and rigid piezoelectric step motor with large step size

Qi Wang1 and Qingyou Lu1,2,a

1Hefei National Laboratory for Physical Sciences at Microscale, University of Scienceand Technology of China, Hefei, Anhui 230026, People’s Republic of China

2High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui

230031,People’s Republic of China

Received 11 June 2009; accepted 16 July 2009; published online 14 August 2009 We present a novel piezoelectric stepper motor featuring high compactness, rigidity, simplicity, andany direction operability. Although tested in room temperature, it is believed to work in lowtemperatures, owing to its loose operation conditions and large step size. The motor is implementedwith a piezoelectric scanner tube that is axially cut into almost two halves and clamp holds a hollow shaft inside at both ends via the spring parts of the shaft. Two driving voltages that singly deform the two halves of the piezotube in one direction and recover simultaneously will move the shaft inthe opposite direction, and vice versa. ? 2009 American Institute of Physics.

DOI: 10.1063/1.3197381

I. INTRODUCTION

The scanning probe microscope(SPM)is a powerful tool in the ?eld of nanotechnology with some important types having atomic or even subatomic resolutions. One key component of an SPM is its coarse approach positioner

which brings the tip and sample as close as in nanometer range and is many times a piezoelectric motor.1–11 The piezo-motor has nevertheless other important applications such as mirror positioning in modern optics12 and cell or DNA manipulations.13

Up to now, there are many kinds of piezomotors found in literatures including Inchworm,3,14–19 beetle type,5–7,10,20–22 shear piezostepper,2,8,9,11,23,24 and inertial slider,4,25–28 etc.However, they all have severe drawbacks. For the ?rst three

types, each needs three or more piezoelectric actuators to operate, which is too complicated in both structure and control. Their reliability and applications in small space(extreme condition environments)and weak signal measurements all become severe issues. Inertial slider is rather simple, but not very rigid(prone to vibration, thus downgrading the quality of atomic images)and unable to produce enough pushing force.

In this paper, we demonstrate a piezoelectric motor that does not have the above limitations. It is implemented by a single piezoelectric scanner tube(PST) that is axially and deeply cut into almost two halves and grips a hollow shaft

(HS)inside from both ends by the spring parts of the HS.Two driving voltages that separately deform the two halves of the PST in one direction and concurrently recover will move the HS one step in the opposite direction, and vice versa. Its compactness, simplicity, rigidity, and large step

size make it particularly useful in small space(extreme conditions)and low temperature

applications.

II. DESIGN AND PRINCIPLE

Figure 1 shows the schematic of our design. A photo of the actual setup is given in Fig. 2. Two sapphire rings of 1.5mm thick by 7.9 and 10.2 mm inner versus outer diameters are glued(with H74F epoxy from Epoxy Technology)onto

the ends of a four-quadrant PST(model PT130.24 of Physik Instrumente, 30 mm long by 10 mm outer diameter by 0.5mm wall thickness with ±200 V maximum operating voltages), respectively. A cut(with diamond saw)through two opposite boundaries of the quadrants is made from the sapphire ring at one end of the PST into about 92% of the tube length toward the other end. The uncut sapphire ring is the base ring, whereas the other is cut into two semi rings which are called clamping semi rings(will clamp hold a mobile HS).Each pair of the neighboring electrodes with no cut in between is wired together, resulting in two semicylindrical electrodes, one is arbitrarily called the ?rst electrode (E1)for convenience and the other, the second electrode(E2).The two halves of the PST that E1 and E2 control are abbreviated as P1 and P2, respectively.

The moving part of the motor is a titanium HS that is inserted into the PST as shown in Fig.1(a).We have studied a circular and a square HS as illustrated in Fig.1(b). For the circular one(length=45mm,inner diameter=5.8mm, and outer diameter= 7.8 mm which can pass through the sapphire rings at the PST ends with a small gap of 0.05 mm),a wire cut through the axis is made from each end toward the other end with the cutting planes perpendicular to each other.The two cuts do not go through the entire HS and a small length of 0.8 mm remains uncut at each end. The pair of the HS cut slits having the opening toward the same direction as that of the PST slits is arranged in the same plane with the PST slits. A stronger compression spring is secured in the HS at one end, pushing the HS to open wider and press against the clamping semi rings with forces N1 and N2,respectively,whereas a weaker compression spring in the HS at the other end presses the HS on the base ring with a total pressing force N br.The three pressing forces N1,N2,and N br are set roughly equal by the above stronger and weaker compression springs. Accordingly, the maximum static friction forces on the HS due to these three pressing forces are approximately equal in value(directions may be opposite as discussed below)if equal friction coef?cients are assumed.

FIG.1.(a)The structure of our piezomotor;(b)two kinds of hollow shafts

studied.

One big advantage of this mutual clamping between the PST and HS at both ends is that this structure is very ?rm(resistant to vibration noise)and can be installed in any direction. Also note that the clamping is elastic(long range forces),implying that large temperature variations will not change the clamping forces signi?cantly and the three maximum static frictions remains equal in value.

To operate the motor, two driving voltages D1 and D2 of Fig.3(a)type are applied to the electrodes E1 and E2 of the PST, respectively(the inner electrode voltage is ?xed at -200 V), which will deform the corresponding semitubular actuators P1 and P2 as follows. P1 and P2 are initialized to expansion states during the ?rst 1/6 period(T1).In T2,P2 shrinks while P1 stays unchanged. This results in a sliding between the free end of P2 and HS rather than a sliding between the base ring and HS, because the P2-to-HS maximum static friction fr2 is smaller than the sum of the P1-to-HS and base ring-to-HS maximum static frictions, fr1+

fr br(assuming these frictions are much smaller than the blocking forces F bl1 and F bl2 of P1 and P2). Next, in T3, P1and P2 both stay in the previous state. This purely “wait”state is a preparation for good synchrony in the next action,which is not necessary and can be dropped to save time. In T4, P1 shrinks while P2 stays unchanged. This induces a sliding between the

free end of P1 and HS(y the similar reason to the T2 action).Up to now, both P1 and P2 have

changed the states from expansion to contraction without moving the HS with reference to the base ring. T5 is another wait which is again discardable.In the last 1/6 period(T6),P1 and P2 both expand simultaneously. This time, the sliding happens only between the base ring and HS because fr br

Finally, P1 and P2 return to the initial states and the HS has moved one step. This sequence can be repeated to achieve a large travel range. The HS can also move in the opposite direction using the driving voltage given in Fig.3(b)and the principle is very similar.

FIG.2.The photo of our piezoelectric motor.

FIG. 3.(a)The two driving voltages which move the HS in the expansion

direction of the PST.(b)The two driving voltages which move the HS in the

contraction direction of the PST.

Apart from the circular HS described above, we have also tried a square HS (42 mm long by 5.6 mm wide, wall thickness is 0.7 mm),which is wire cut from each end to the other

end(cutting length= 35 mm)with the cutting planes parallel to each other, forming a serpentine structure as exhibited in Fig.1 (b). The distance between the cutting planes is 0.8 mm. This design is better than its circular counterpart in the following aspects:(1)the sliding of the HS on the sapphire rings is like ice skating shoes sliding on ice, allowing bigger pressing forces more rigid without increasing the frictions;(2)the fri ctions are better de?ned and more stable;(3)only one compression spring is needed, whose position in the square HS can be adjusted to meet the optimal working condition of fr1≈fr2≈fr br;(4)the smallest gap between the

square HS and the sapphire rings is easier to tweak by grinding(smaller gap will lead to a larger travel range).

FIG.4.The schematic diagram for deriving the range of motion.

Apparently, the clamping forces N1,N2,and N br do not remain constant when the HS moves, thus limiting its range of motion.The range of motion for the square HS can be derived as follows. Referring to Fig.4 in which F S is the force produced by the spring and L B and L C stand for the distances from the spring to the base ring and to the clamping semi rings, respectively, the lever law leads to:L B·F S=(N1+N2)·(L C+L B) and L C·F S=N br·(L C+L B).Because N1=N2 and we need N1+N2>N br for the HS to walk, this means that L B>L C should be satis?ed. Since the HS cannot move if L C=0, the range of motion is ?nally determined by0

III. PERFORMANCE TEST

We have tested the room temperature performance 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, respectively]and operating voltage[Figs.5(b)and 6(b)for circular and square HS, respectively]. The pressing forces were set to N1≈N2≈N br≈0.22N for circular HS which are much smaller than the blocking forces

(F bl1～F bl2～2N)of the driving piezo-P1 and P2.

The maximum step size is 12.9 m with the measurement conditions being: circular HS, downward stepping with0.3 Hz driving frequency. When the moving direction 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 types of piezoelectric motors9,11,23with the similar size.The speed of motion is of course closely related to the driving frequency. The maximum driving frequency we set was50 Hz,

at which the speeds for the circular(upward versus downward) and square(upward versus downward)HS were:(22.27 versus 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 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.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 helium 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|≈|fr2|≈|fr br|,in a very wide temperature range since a change 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 scratched 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 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. CONCLUSION

We have presented a powerful 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 been tested,which is rather good.All these are highly desired in the construction of a modern SPM.

ACKNOWLEDGMENTS

This 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 The Chinese Academy of Sciences under Grant No. YZ200846.

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