單片機步進(jìn)電機控制系統(tǒng)外文文獻(xiàn)翻譯

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1、本科畢業(yè)設(shè)計（論文）外文翻譯譯文 1、外文翻譯是畢業(yè)設(shè)計（論文）的主要內(nèi)容之一，必須學(xué)生獨立完成。 2、外文翻譯譯文內(nèi)容應(yīng)與學(xué)生的專業(yè)或畢業(yè)設(shè)計（論文）內(nèi)容相關(guān)，不得少于 15000印刷符號。 3.外文翻譯譯文用A4紙打印。文章標(biāo)題用3號宋體，章節(jié)標(biāo)題用4號宋體，正文 用小4號宋體，20磅行距；頁邊距上、下、左、右均為 2.5cm,左側(cè)裝訂，裝訂線 0.5cm。按中文翻譯在上，外文原文在下的順序裝訂。 4、年月日等的填寫，用阿拉伯?dāng)?shù)字書寫，要符合《關(guān)于出版物上數(shù)字用法的試行 規(guī)定》，如“ 2005年2月26日”。 5、所有簽名必須手寫，不得打印 簡單緊湊的大步長線性壓電步進(jìn)電機

2、 Qi Wangl and Qingyou Lu1,2,a） 1合肥微物質(zhì)科學(xué)國家實驗室，中國科學(xué)技術(shù)大學(xué)，安徽合肥 230026,中華人民共和國 2強磁場實驗室，中國科學(xué)院，安徽合肥 230031,中華人民共和國的中國（2009.6.11 接收；2009.7.16通過；2009.8.14網(wǎng)絡(luò)出版） 我們提出一篇關(guān)于新型壓電步進(jìn)電機的文章，它具有高密度，剛性，簡單，和任 意方向可操作性的特點。雖然測試在室溫下進(jìn)行，但是由于寬松的操作條件和大步 長，該電機也能在低溫下工作。電機由一個壓電掃描器管來運行，它的軸向幾乎被切 成兩半，通過軸的彈簧部分夾持一個空心軸內(nèi)部兩端。雙驅(qū)動電壓僅使壓力管的兩

3、部 分在一個方向上變形，且能反向移動軸承以恢復(fù)原狀，反之亦然。 ？美國物理研究所 [工業(yè)部：10.1063/1.3197381] 一. 簡介 掃描探針顯微鏡（SPM在一些有重要類型的原子甚至是亞原子研究的納米技術(shù)領(lǐng) 域是一個功能強大的工具。顯微鏡的一個關(guān)鍵組成部分，就是它那個能在納米范圍內(nèi) 粗略接近被測物的末端或者樣品的定位器，這多半需要一個壓電步進(jìn)電機。 1-11壓電電 動機在其他領(lǐng)域也有重要應(yīng)用，例如顯微鏡在現(xiàn)代光學(xué) 12,細(xì)胞或者DNA空制中的定位 13 o 到現(xiàn)在為止，在尺蟆3,14-19、甲蟲類生物5-7,10,20-22、剪切壓電步進(jìn)電機2,8,9,11,23,24 ,慣

4、 性滑塊4,25-28等文獻(xiàn)中找到了各種各樣的壓電電動機。然而，他們都有著嚴(yán)重的缺點。 對于前三種而言，每一種都需要三個或者更多的電壓驅(qū)動才能被操作，這使得電機的 結(jié)構(gòu)和控制都變得太過復(fù)雜。在小領(lǐng)域（極端環(huán)境條件）或者微信號測量等方面，他 們的可靠性和應(yīng)用程度成為了一個很大的問題。慣性滑塊雖然簡單，但是特性不夠硬 （容易產(chǎn)生振動，從而降低了原子圖像的品質(zhì)），并且無法產(chǎn)生足夠的推動力。 在這片文章中，我們闡述了一個不具有以上限制的壓電電動機。電機由一個壓電 掃描器管（PST來運行，它的軸向幾乎被切成兩半，通過軸上的彈簧部分夾持一個空 心管（HS）內(nèi)部兩端。雙驅(qū)動電壓僅使壓力管的兩部分在一個方

5、向上變形，且能反向 移動軸承以恢復(fù)原狀，反之亦然。其緊湊，簡單，剛度，和大步長的特性使其在小空 問（極端條件下）和低溫應(yīng)用中非常有用。 a）作者的聯(lián)系方式如下。電話：86-551-360-0247。電子郵箱：qxl@。 二.設(shè)計原理 圖1為我們設(shè)計的原理圖。圖2為實物圖。兩個1.5mm厚的藍(lán)色環(huán)粘（采用了來 自環(huán)氧樹脂技術(shù)的環(huán)氧樹脂）在了 7.9mm內(nèi)徑、10.2mm外徑的壓電掃描管（壓電掃描 管物理模型130.24,長30mm外徑10mm壁厚0.5mm，有 200V的最大工作電壓）的 整個外環(huán)邊緣處。在壓電掃描管的外徑藍(lán)色環(huán)上切兩個相對的切口，長度從一段的藍(lán) 色環(huán)到另一端的藍(lán)色環(huán)，總長

6、大概占到整個壓電掃描管的 92%勺長度。為被切到的藍(lán)色 環(huán)是粘在基環(huán)上的，另外一個藍(lán)色環(huán)被切成了兩半，它被稱作半夾持環(huán)(夾持一個可 轉(zhuǎn)動的空心管)。沒對沒有被切割的相鄰電極用導(dǎo)線連在了一起，形成兩個半圓柱形電 極，任意一個稱為電極1 (E1),為了方便，把另一個稱為電極 2 (E2)。由E1和E2控 制的壓電掃描管的兩部分分別簡稱為 P1, P2。 電機可移動部分是一個鈦合金空心管，它被插入到壓電掃描管的內(nèi)部，如圖 1 (a)所示。我們還研究過圓形和方形的空心管，如圖 1 (b)所示。對于圓形空心管而 言(長45mm內(nèi)徑5.8mm外徑7.8mm穿過藍(lán)色環(huán)到達(dá)壓電掃描管的邊緣并形成一個 0

7、.05mm的間隙)，導(dǎo)線從與他垂直的平面的一段管過軸到另一端。兩個切割線不會穿過 整個空心管，會在每端留下 0.8mm的未切割部分?？招墓芮谐糠值哪菍障冻?方向打開，并且和壓電掃描管上分布的縫隙是同一方向。一個彈性很強的彈簧被牢固 的固定在空心管的一端，推動空心管的打開，分別對夾持的半環(huán)施加 N和N2的推力， 同時空心管另一端一個較弱的壓縮彈簧讓空心管給基換施加一個總的壓力 Nbro N, N2 和Nbr在上述較強和較弱的壓縮彈簧上能大致平衡。因此，只要兩者的摩擦系數(shù)相等， 那么施加在空心管的最大靜摩擦力會因為這三個壓力的大致相等而抵消(方向可能與 下面討論的相反)。 Half

8、PST (PI) Half PST (P2) Cut via two opposite — . , boundaries Clamping semi ring (sapphire) Uncut electrode boundary Base ring (sapphire) (a) Hollow shaft Piezoelectric scanner tube (PST) Circular hollow shaft （b） 圖1 （a）我們的壓電電機的結(jié)構(gòu)（b）兩種空心管的研究 這種在壓電掃描管和空心管兩段互相夾持的結(jié)構(gòu)有一個很大的好處

9、，就是這種結(jié) 構(gòu)很穩(wěn)定（耐振動噪聲），能在任意方向上安裝。同時也應(yīng)注意到，這種夾持結(jié)構(gòu)是靈 活的（大范圍的力），這表明較大的溫度變化不會引起夾持力顯著的變化，且這三個最 大靜摩擦力任然可以保持平衡。 為了能控制電機，圖3 （a）所示的兩個驅(qū)動電壓 D1和D2分別適用于壓電掃描管 的電極E1和E2 （內(nèi)部電極電壓定為-200V）,這能試相對的半圓形螺線管 P1和P2變 形，如下圖所示。在第一個1/6周期（T1）內(nèi)，P1和P2初始化狀態(tài)。在T2內(nèi)，P1保 持不變，P2收縮。這會導(dǎo)致P2和空心管的自由端的電壓下降，而不是基環(huán)和空心環(huán)指 間電壓的下滑，因為 P2到空心管的最大靜摩擦力小于 fr2

10、小于P1到空心管與基環(huán)到 空心管的最大靜摩擦力之和，fri+fr br （假設(shè)這些摩擦力遠(yuǎn)遠(yuǎn)小于 P1和P2的阻力Fbl1和 國2）。下一時間段，T3, P1和P2保持在之前的狀態(tài)。這種純粹的“等待”是為下一步 的同步做好準(zhǔn)備，這不是必須的，可以去掉來節(jié)省時間。在 T4時間內(nèi)，P1收縮，P2 保持不變。這會導(dǎo)致P1和空心管的自由端電壓下降（與 T2時間的動作原因一樣）。到 現(xiàn)在為止，P1和P2都已經(jīng)在基于基礎(chǔ)環(huán)，沒有移動空心管的情況下從擴張的狀態(tài)變到 收縮的狀態(tài)。T5是另外一個等待時間，它也是可以去掉的。在最后一個 1/6周期 （T6）內(nèi)，P1和P2同時擴張。這次僅在基礎(chǔ)環(huán)和空心環(huán)之間的電壓

11、發(fā)生了下滑，因為 fr b「＜fr i+fr 2,這意味著P1和P2同時拖動著空心管從基環(huán)擴張的方向上移動了一步。 HS ;square； Half PST Electrode wire Clamping semi ring (sapphire) Cut via two opposite boundaries Copper plate for mounting ase ring (sapphire) Uncut electrode boundary 最后，Pi和P2回到最初狀態(tài)，空心環(huán)移動了一步?？招沫h(huán)也可以使用如圖 3 （b）所 示的驅(qū)動電壓在相反的方向上移

12、動，原理是類似的。 圖2壓電電機的實物圖 除了上述討論的原型空心管，我們也嘗試了方形空心管（ 42mm長,5.6mm寬，壁 厚0.7mm）,它的壁從一段到另一端進(jìn)行了線切割（切割長度 35mrm,與另一個切割線 互相平行，組成了一個蛇形的結(jié)構(gòu)，如圖 1 （b）所示。切割平面之間的距離是 0.8mm這種設(shè)計比圓形的設(shè)計相對以下方面要好： （1）空心管在藍(lán)環(huán)上的滑落就想溜 冰鞋在冰上的滑行，允許更大的壓力（更線性）卻又不會有更多的阻力； （2）阻力值 更精確，更穩(wěn)定；（3）只需要一個壓力彈簧，它在方形空心管的位置能滿足最佳的工 作條件fr i-fr 2-fr br； （4）方形空心管和藍(lán)色

13、環(huán)指間的最小空隙容易調(diào)整扭曲（較小 的空隙容易形成較大的運行距離） (a) 圖3 （a）趨勢空心管朝壓電掃描管方向擴張的兩個驅(qū)動電壓（ b）趨勢空心管朝壓電掃描 管相反方向擴張的兩個驅(qū)動電壓 顯然的，夾持力N1, N2和Nbr在空心管運動時不是一直存在的，因此需要限制它 的運動范圍。方形空心管的運動范圍可以從下述方式獲得。在圖 4中，彈簧產(chǎn)生的理 Fs, LB和LC分別代表從彈簧到基環(huán)，從彈簧到半圓形夾持環(huán)的距離，由杠桿原理可 知：Lb? Fs=（Ni+N） ? （Lc+Lb）,L「Fs=Nr?（Lc+Lb）。因為 Ni=N,我們要求 N+N>N「以使 空心管運

14、動，這就意味著 LB>LC這個條件應(yīng)該滿足。因為如果 Lc=0,空心管不能運 動，那么運動范圍最終由 0

15、，工作頻率 ［分別如圖5 (a)的原型空心管和圖 6 (a)的方形空心管］,工作電壓［分別如圖5 (b)的原型空心管和圖 6 (b)的方形空 心管］。圓形空心管的壓力值設(shè)為 N=N = M=0.22N,這個值遠(yuǎn)遠(yuǎn)小于驅(qū)動壓電 P1和 P2的阻力值(Fbii?Fbi2?2N)。 最大步長是12.9Nm^測試條件是：0.3Hz向下滑的驅(qū)動頻率帶動的圓形空心管。 當(dāng)移動方向變?yōu)橄蛏系臅r候，步長因為重力變?yōu)?11.7 pm1如果是方形空心管，向下的 步長和向上的步長分別是8.9仙m和8.2仙簿 這個值更為合適，因為他的切割邊緣與藍(lán) 色環(huán)相接。所有這些步長值都比其他類似大小的壓電電機 9,11,

16、23的步長要大。電機 的轉(zhuǎn)速當(dāng)然和驅(qū)動頻率很接近。我們設(shè)置的最大驅(qū)動頻率是 50Hz,圓形空心管(向上 運行對向下運行)和方形空心管(向上運行對向下運行)的轉(zhuǎn)速分別是( 22.27對 24.62) (19.44 對 19.8) mm/min 當(dāng)驅(qū)動頻率上升或者工作電壓值下降的時候，步長的下降情況如圖 5和圖6所 示。雖然我們從圓形空心管中獲得了較大的步長，但是我們更傾向于使用方形空心 管，因為它的優(yōu)點限制更少。例如，方形空心管的運行范圍是 9mm(理論上)，而圓形 空心管的運行范圍是 3.3mm (比方形的在理論上少了 6.6mm)。方形空心管電機的運行 曲線如圖6所示，比圓形空

17、心管電機的曲線更平滑更穩(wěn)定。 雖然測試是在室溫條件下進(jìn)行的，但是電機在固化氮的溫度下工作也有很大潛 力，原因有兩個：大步長的特性可以應(yīng)對熱量下降帶來的問題，保持運行的穩(wěn)定； (2)它的彈簧夾持結(jié)構(gòu)可以讓壓力彈簧(? 5mm長，勁度系數(shù)大約是286N/M在從室 溫到固化氮的很大的溫度范圍變化下僅有微米級的下滑，確保必要的摩擦力關(guān)系的成 立，|fr i| =|fr 2| =|fr b「|,這種變化對于空心管和藍(lán)色環(huán)之間的壓力值的影響可以忽略 不計。 方形空心管可以承受磨損和撕裂的問題，因為它的四個邊緣可以被藍(lán)色環(huán)固定 為了測試它的耐久度，我們在 200V和50Hz的驅(qū)動電壓下超過一千次

18、的3mmi勺替換條 件下操作電機，電機任然能正常工作。磨損不嚴(yán)重。當(dāng)然，空心管外部可以加上耐磨 金屬材料進(jìn)行更好的保護(hù)（如果需要的話）。 Frequency (Hz) Speed (mnvmim 0 5 0 5 2 11 3 2 1^987 1- 1 1 -1 (Erl)心Nwd2s 40 60 80 100 120 14。160 180 200 220 士Voltage per step(V) —Downward -a- - LlpwarcJ^ (b) 圖5 用圓形空心管測試的電機步長（左側(cè)垂直軸）和速度（右側(cè)垂直軸） （a）頻率（最大

19、工作電壓= 200V） （b）最大工作電壓（頻率=20HZ Speed (mmfm-n) 0 5 0 5 0 2 11 0 5 0 5 0 5 9 8 8 7 7 6 一■一 Downward 一?— Upward (Ed) ds 1 r I 1 I 1 I 1 I 1 I 0 10 20 30 40 50 8 7 6 5 4 3 2 alNG dols ㈤ Frequency (Hz) 1 - 0- r i t r i T r T 1 r 1 1 1 T 1 1 t 1 40 60 80 100 120 140 160 180 200 220 tVolta

20、ge per step（V） （b） 圖6用圓形空心管測試的電機步長（左側(cè)垂直軸）和速度（右側(cè)垂直軸） （a） 頻率（最大工作電壓=200功（b）最大工作電壓（頻率=20HZ） 四.結(jié)束語 我們呈現(xiàn)了一個強大的線性壓電電動機，它擁有其他壓電電動機不能同時具有的 幾個重要特性，包括：大步長，小尺寸，剛性，結(jié)構(gòu)簡單，操作方便，溫度范圍大， 易形成不精確的加工公差等。耐久度測試結(jié)果非常好。在建設(shè)一個現(xiàn)代化的掃描探針 顯微鏡中，所有這些性能都是非常需要的。 致謝 這項工程得到了中國國家自然科學(xué)基金 10627403號，中國國家強磁場設(shè)施計劃和中國 科學(xué)院自然科學(xué)基金 YZ2008

21、46的資助。 原文： A simple, compact, and rigid piezoelectric step motor with large step size Qi Wangl and Qingyou Lu1,2,a Hefei National Laboratory for Physical Sciences at Microscale, University of Scienceand Technology of China, Hefei, Anhui 230026, People s Republic of China 2High Magnetic Field L

22、aboratory, Chinese Academy of Sciences, Hefei, Anhui 230031,People s Republic of Chin 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. Althou

23、gh 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 hollowshaft inside at both ends via the spring

24、 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 mi

25、croscope(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

26、11 The piezo-motor has nevertheless other important applications such as mirror positioning in modern optics12 and cell or DNA manipulations.13 ., . - . ? ? ?? . 3 14 Up to now, there are many kinds of piezomotors found in literatures including Inchworm, 19 beetle type”,10,20 22 shear piezostep

27、pe2；8,9,11,23,24 and inertial slider,4,25" 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 e

28、nvironments)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 thadoes not have

29、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 halvesof the PST in one dire

30、ction and concurrently recover willmove the HS one step in the opposite direction, and viceersa. 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 s

31、chematic of our design. A photo ofthe actual setup is given in Fig.2. Two sapphire rings of 1.5mm thick by 7.9 and 10.2 mm inner versus outer diametersre glued(with H74F epoxy from Epoxy Technology)onto the ends of a four-quadrant PST(model PT130.24 of Physiknstrumente, 30 mm long by 10 mm outer dia

32、meter 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 tubength toward the other end. The uncut sapphire ring is thbase ring

33、, 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 inbetween is wired together, resulting in two semicylindrical electrodes, one is arbitrarily called the ?rst eletrode (E1)for convenien

34、ce and the other, the second electrode(E2).Thewo halves of the PST that E1 and E2 control are abbreviatedas P1 and P2, respectively. The moving part of the motor is a titanium HS that isinserted into the PST as shown in Fig.1(a).We have studieda circular and a square HS as 川ustrated in Fi0.(b). For

35、 the circular one(length=45mm,inner diameter=5.8mm, andouter diameter= 7.8 mm which can pass through the sapphire rings at the PST ends with a small gap of 0.05 mm)wiire cut through the axis is made from each end toward thether end with the cutting planes perpendicular to each other.The two cuts do

36、not go through the entire HS and a smaength of 0.8 mm remains uncut at each end. The pair of thHS cut slits having the opening toward the same direction asthat of the PST slits is arranged in the same plane with theST slits. A stronger compression spring is secured in the HSit one end, pushing the H

37、S to open wider and press againstthe clamping semi rings with forces Ni and N2,respectively,whereas a weaker compression spring in the HS at the otheend presses the HS on the base ring with a total pressingforce Nbr.The three pressing forces N,N2,and Nbr are setroughly equal by the above stronger an

38、d weaker compressioisprings. Accordingly, the maximum static friction forces on the HS due to these three pressing forces are approximateequal in value(directions may be opposite as discussed below)if equal friction coef?cients are assumed. Piezoelectric scanner tube (PST) Hollow shaft Uiamping

39、semi Base ring ring (sapphire) (sapphire) ⑻ Circular hollow shaft (b) FIG.1.(a)The structure of our piezomotor;(b)two kinds of hollow shafts studied. One big advantage of this mutual clamping between the^ST and HS at both ends is that this structure is very ?rm(resistant to vibration

40、noise)and can be installed in any direction. Also note that the clamping is elastic(long rangeorces),implying that large temperature variations will not change the clamping forces signi?catly and the three maximum static frictions remains equal in value. To operate the motor, two driving voltages D

41、1 and D2 ofFig.3(a)type are applied to the electrodes E1 and E2 of theST, respectively(the inner electrode voltage is ?xed at200 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 s

42、hrinks while P1 stays unchanged. This results in a slidindpetween 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? fs smaller than the sum of the P1-to-HS and base ring-to-HS maximum static frictions, f+ frbr(assuming these f

43、rictions are much smaller than thblocking forces Fbli and Fbl2 of P1 and P2). Next, in T3, Pland P2 both stay in the previous state. This purely “wait ” s preparation for good synchrony in the next action,which is not necessary and can be dropped to save time. InT4, Pi shrinks while P2 stays unchan

44、ged. This induces sliding between the free end of Pi and HS(y the similarreason to the T2 action).Up to now, both Pi and P2 havechanged the states from expansion to contraction withoutioving the HS with reference to the base ring. T5 is anotheiwait which is again discardable.In the last 1/6 period(

45、T6),P1 and P2 both expand simultaneously. This time, the slidinghappens only between the base ring and HS because fbr

46、 one step. This sequence can be repeated to achieve fearge travel range. The HS can also move in the opposite direction using the driving voltage given in Fig.3(b)and theprinciple is very similar. FIG.2.The photo of our piezoelectric motor. FIG. 3.(a)The two driving voltages which move the HS in t

47、he 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 havealso 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 theother end(cu

48、tting length= 35 mm)with the cutting planesparallel to each other, forming a serpentine structure as exhibited in Figi (b). The distance between the cutting planess 0.8 mm. This design is better than its circular counterpartn the following aspects:(1)the sliding of the HS on thesapphire rings is lik

49、e ice skating shoes sliding on ice, allowing bigger pressing forces more rigid without increasing the frictions;(2)the frictions are better de?ned and more stable;(3)only one compression spring is needed, whosposition in the square HS can be adjusted to meet the optimaworking condition of fr i - tr=

50、 frr；(4)the smallest gapbetween the er plate ounting  Hollow shaft /(HS) Spring square HS and the sapphire rings is easier tweak by grinding(smaller gap will lead to a larger travel range). Base ring (sapphire) Clamping semi rings (sapphire) FIG.4.The schematic diagram for deriving the

51、range of motion. Apparently, the clamping forces Ni ,N2,and Nbr do not remain constant when the HS moves, thus limiting its rangeof motion.The range of motion for the square HS can be derived as follows. Referring to Fig.4 in which Fs is theforce produced by the spring and Ib and Lc stand for thedi

52、stances from the spring to the base ring and to the clamping semi rings, respectively, the lever law leads to:lB Fs=(Ni+N2)(Lc+Lb) and Lc Fs=Nbr (Lc+LB).Because N1=N2 and we need Ni+N2>Nbr for the HS to walk, this means that Lb>Lc should be satis?ed. Since the HS cannotmove if Lc=0, the range of mot

53、ion is ?nally determined by0

54、 HS). III. PERFORMANCE TEST We have tested the room temperature performance of theotor 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[F

55、igs.5(b)and 6(b)for circular and square HS, respectively]. The pressing forces were set to N產(chǎn) M=Nbr= 0.22N for circularHS which are much smaller than the blocking forces (Fbli ?Fbl2 ?2N)of the driving piezo-PI and P2. The maximum step size is 12.9 m with the measurement conditions being: circular H

56、S, downward stepping with 0.3 Hz driving frequency. When the moving direction is changed to upward, the step size becomes 11.7 m due tgoravity. In case of square HS, the downward and upward stepsizes are 8.9 and 8.2m, respectively, which is more uniform because of its knife edge contacts with the sa

57、pphirerings. All these step sizes are rather large compared withther types of piezoelectric motorJ11,23 with 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 versudow

58、nward) 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 diminishesas seen in Figs.5 and 6. Although we get larger step sizefrom circular HS, we still pr

59、efer the square HS owing to itsadvantages listed earlier. For instance, the travel range usingthe square HS is 9 mm(as designed)compared with 3.3 mrfor the circular HS(worse than the designed 6.6mm travelange).The performance curves of the square HS motor seerin Fig.6 are also smoother and more cons

60、istent than those (F5)of the circular HS motor. Speed2 (a) 40 60 80 WO 120 140 t60 WO 200 220 土Voltage per step(V) (b) 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) a

61、nd (b) maximum operating voltage (frequency=20 Hz). Although tested in room temperature, the motor has highpotential 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

62、;(2)its spring clamping structure validates therequired friction relationship,|fri| = fr- f|,in a verywide 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

63、 affect the pressing forceS)etween the HS and the sapphire rings. The square HS may suffer wear and tear issues as four edges could be scratched by the sapphire rings. To testts durability, we operated the motor repeatedly with 200 V and 50 Hz driving voltages for more than one thousand timewith a

64、 displacement about 3 mm and the motor still worked well. The wear was not severe. Of course, the HS can beoated with wear resistant materials for better protection ifiecessary. 0 10 2。 30 40 5。 Frequency (Hz) Speed (mm-m-n) (a) 81 Downward , 7 ] ―*— Upward /y 40 60 80 100 120 140 160 1

65、80 200 220 上Voltage per step(V) ----------6 5 4 3 2 1 1T1)& s dQJS (b) 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.

66、 CONCLUSION We have presented a powerful linear piezoelectric motorhat owns several important features not simultaneouslyowned by other piezomotors,including: large step size,small size,very rigid,simple in structure and operation, very largetemperature range, easy to make and loose machining tolerance,etc. Its durability has also been tested,which is rathgood.All these are highly desired in the construction of anodern SPM. 指導(dǎo)教師意見: 指導(dǎo)教師簽字： 年 月 日 系（教研室）意見: 主任簽字： 年 月