單片機(jī)步進(jìn)電機(jī)控制系統(tǒng)外文文獻(xiàn)翻譯--簡(jiǎn)單緊湊的大步長(zhǎng)線性壓電步進(jìn)電機(jī)

1、<p><b>　　中文3857字</b></p><p>　　本科畢業(yè)設(shè)計(jì)（論文）外文翻譯譯文</p><p><b>　　要 求</b></p><p>　　1、外文翻譯是畢業(yè)設(shè)計(jì)（論文）的主要內(nèi)容之一，必須學(xué)生獨(dú)立完成。</p><p>　　2、外文翻譯譯文內(nèi)容應(yīng)與學(xué)生的專業(yè)或畢業(yè)

2、設(shè)計(jì)（論文）內(nèi)容相關(guān)，不得少于15000印刷符號(hào)。</p><p>　　3.外文翻譯譯文用A4紙打印。文章標(biāo)題用3號(hào)宋體，章節(jié)標(biāo)題用4號(hào)宋體，正文用小4號(hào)宋體，20磅行距；頁(yè)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。</p><p>　　4、年月日等的填寫(xiě)，用阿拉伯?dāng)?shù)字書(shū)寫(xiě)，要符合《關(guān)于出版物上數(shù)字用法的試行規(guī)定》，如“2005年

3、2月26日”。</p><p>　　5、所有簽名必須手寫(xiě)，不得打印。</p><p>　　簡(jiǎn)單緊湊的大步長(zhǎng)線性壓電步進(jìn)電機(jī)</p><p>　　Qi Wang1 and Qingyou Lu1,2,a)</p><p>　　1 合肥微物質(zhì)科學(xué)國(guó)家實(shí)驗(yàn)室，中國(guó)科學(xué)技術(shù)大學(xué)，安徽合肥230026，中華人民共和國(guó)</p><p&

4、gt;　　2強(qiáng)磁場(chǎng)實(shí)驗(yàn)室，中國(guó)科學(xué)院，安徽合肥230031，中華人民共和國(guó)的中國(guó)(2009.6.11接收；2009.7.16通過(guò)；2009.8.14網(wǎng)絡(luò)出版)</p><p>　　我們提出一篇關(guān)于新型壓電步進(jìn)電機(jī)的文章，它具有高密度，剛性，簡(jiǎn)單，和任意方向可操作性的特點(diǎn)。雖然測(cè)試在室溫下進(jìn)行，但是由于寬松的操作條件和大步長(zhǎng)，該電機(jī)也能在低溫下工作。電機(jī)由一個(gè)壓電掃描器管來(lái)運(yùn)行，它的軸向幾乎被切成兩半，通過(guò)軸的彈簧

5、部分夾持一個(gè)空心軸內(nèi)部?jī)啥?。雙驅(qū)動(dòng)電壓僅使壓力管的兩部分在一個(gè)方向上變形，且能反向移動(dòng)軸承以恢復(fù)原狀，反之亦然。©美國(guó)物理研究所</p><p>　　[工業(yè)部: 10.1063/1.3197381]</p><p><b>　　簡(jiǎn)介</b></p><p>　　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)

6、域是一個(gè)功能強(qiáng)大的工具。顯微鏡的一個(gè)關(guān)鍵組成部分，就是它那個(gè)能在納米范圍內(nèi)粗略接近被測(cè)物的末端或者樣品的定位器，這多半需要一個(gè)壓電步進(jìn)電機(jī)。1-11壓電電動(dòng)機(jī)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控制中的定位13。</p><p>　　到現(xiàn)在為止，在尺蠖3,14-19、甲蟲(chóng)類生物5-7,10,20-22、剪切壓電步進(jìn)電機(jī)2,8,9,11,23,24，慣性滑塊4,25-28等文獻(xiàn)中找到了各

7、種各樣的壓電電動(dòng)機(jī)。然而，他們都有著嚴(yán)重的缺點(diǎn)。對(duì)于前三種而言，每一種都需要三個(gè)或者更多的電壓驅(qū)動(dòng)才能被操作，這使得電機(jī)的結(jié)構(gòu)和控制都變得太過(guò)復(fù)雜。在小領(lǐng)域（極端環(huán)境條件）或者微信號(hào)測(cè)量等方面，他們的可靠性和應(yīng)用程度成為了一個(gè)很大的問(wèn)題。慣性滑塊雖然簡(jiǎn)單，但是特性不夠硬（容易產(chǎn)生振動(dòng)，從而降低了原子圖像的品質(zhì)），并且無(wú)法產(chǎn)生足夠的推動(dòng)力。</p><p>　　在這片文章中，我們闡述了一個(gè)不具有以上限制的壓電電動(dòng)機(jī)

8、。電機(jī)由一個(gè)壓電掃描器管（PST）來(lái)運(yùn)行，它的軸向幾乎被切成兩半，通過(guò)軸上的彈簧部分夾持一個(gè)空心管（HS）內(nèi)部?jī)啥?。雙驅(qū)動(dòng)電壓僅使壓力管的兩部分在一個(gè)方向上變形，且能反向移動(dòng)軸承以恢復(fù)原狀，反之亦然。其緊湊，簡(jiǎn)單，剛度，和大步長(zhǎng)的特性使其在小空間（極端條件下）和低溫應(yīng)用中非常有用。</p><p>　　a)作者的聯(lián)系方式如下。電話：86-551-360-0247。電子郵箱：qxl@ustc.edu.cn。<

9、/p><p><b>　　設(shè)計(jì)原理</b></p><p>　　圖1為我們?cè)O(shè)計(jì)的原理圖。圖2為實(shí)物圖。兩個(gè)1.5mm厚的藍(lán)色環(huán)粘（采用了來(lái)自環(huán)氧樹(shù)脂技術(shù)的環(huán)氧樹(shù)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(zhǎng)30mm，外徑10mm，壁厚0.5mm，有±200V的最大工作電壓）的整個(gè)外環(huán)邊緣處。在壓電掃描管的外徑藍(lán)色環(huán)上切兩

10、個(gè)相對(duì)的切口，長(zhǎng)度從一段的藍(lán)色環(huán)到另一端的藍(lán)色環(huán)，總長(zhǎng)大概占到整個(gè)壓電掃描管的92%的長(zhǎng)度。為被切到的藍(lán)色環(huán)是粘在基環(huán)上的，另外一個(gè)藍(lán)色環(huán)被切成了兩半，它被稱作半夾持環(huán)（夾持一個(gè)可轉(zhuǎn)動(dòng)的空心管）。沒(méi)對(duì)沒(méi)有被切割的相鄰電極用導(dǎo)線連在了一起，形成兩個(gè)半圓柱形電極，任意一個(gè)稱為電極1（E1），為了方便，把另一個(gè)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(jiǎn)稱為P1，P2。</p><p>　　電機(jī)可移動(dòng)

11、部分是一個(gè)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(guò)圓形和方形的空心管，如圖1（b）所示。對(duì)于圓形空心管而言（長(zhǎng)45mm，內(nèi)徑5.8mm，外徑7.8mm，穿過(guò)藍(lán)色環(huán)到達(dá)壓電掃描管的邊緣并形成一個(gè)0.05mm的間隙），導(dǎo)線從與他垂直的平面的一段管過(guò)軸到另一端。兩個(gè)切割線不會(huì)穿過(guò)整個(gè)空心管，會(huì)在每端留下0.8mm的未切割部分?？招墓芮谐糠值哪菍?duì)空隙朝同一方向打開(kāi)，并且和壓電掃描管上分布的縫隙是同一方向。一個(gè)彈

12、性很強(qiáng)的彈簧被牢固的固定在空心管的一端，推動(dòng)空心管的打開(kāi)，分別對(duì)夾持的半環(huán)施加N1和N2的推力，同時(shí)空心管另一端一個(gè)較弱的壓縮彈簧讓空心管給基換施加一個(gè)總的壓力Nbr。N1，N2和Nbr在上述較強(qiáng)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(huì)因?yàn)檫@三個(gè)壓力的大致相等而抵消（方向可能與下面討論的相反）。</p><p>　　圖1（a）我們的壓電電機(jī)的結(jié)構(gòu)（b）兩種空心管

13、的研究</p><p>　　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(gè)很大的好處，就是這種結(jié)構(gòu)很穩(wěn)定（耐振動(dòng)噪聲），能在任意方向上安裝。同時(shí)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(huì)引起夾持力顯著的變化，且這三個(gè)最大靜摩擦力任然可以保持平衡。</p><p>　　為了能控制電機(jī)，圖3（a）所示的兩個(gè)驅(qū)動(dòng)電壓D1和D2分別適用于壓電掃描管的電極E1和E2（

14、內(nèi)部電極電壓定為-200V），這能試相對(duì)的半圓形螺線管P1和P2變形，如下圖所示。在第一個(gè)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(huì)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?yàn)镻2到空心管的最大靜摩擦力小于fr2小于P1到空心管與基環(huán)到空心管的最大靜摩擦力之和，fr1+frbr（假設(shè)這些摩擦力遠(yuǎn)遠(yuǎn)小于P1和P2的阻力Fbl1和Fbl2）。下一時(shí)間段，T3，P1和P2保

15、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(lái)節(jié)省時(shí)間。在T4時(shí)間內(nèi)，P1收縮，P2保持不變。這會(huì)導(dǎo)致P1和空心管的自由端電壓下降（與T2時(shí)間的動(dòng)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(méi)有移動(dòng)空心管的情況下從擴(kuò)張的狀態(tài)變到收縮的狀態(tài)。T5是另外一個(gè)等待時(shí)間，它也是可以去掉的。在最后一個(gè)1/6周期（T6）內(nèi)，P1和P2同時(shí)擴(kuò)張。這次僅在基礎(chǔ)環(huán)和空心環(huán)之間的電壓發(fā)生了下滑，因?yàn)閒rbr

16、<fr1+fr2，這意味著P</p><p>　　圖2 壓電電機(jī)的實(shí)物圖</p><p>　　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(zhǎng)，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(zhǎng)度35mm），與另一個(gè)切割線互相平行，組成了一個(gè)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(jì)比圓形的設(shè)計(jì)相對(duì)以下方面要好：（1）空心

17、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(huì)有更多的阻力；（2）阻力值更精確，更穩(wěn)定；（3）只需要一個(gè)壓力彈簧，它在方形空心管的位置能滿足最佳的工作條件fr1≈fr2≈frbr；（4）方形空心管和藍(lán)色環(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(yùn)行距離）。</p><p>　　圖3（a）趨勢(shì)空心管朝壓電掃描管方向擴(kuò)張的兩個(gè)驅(qū)動(dòng)電壓（b）趨勢(shì)空心管朝壓電掃描管相反方向擴(kuò)張的兩個(gè)

18、驅(qū)動(dòng)電壓</p><p>　　顯然的，夾持力N1，N2和Nbr在空心管運(yùn)動(dòng)時(shí)不是一直存在的，因此需要限制它的運(yùn)動(dòng)范圍。方形空心管的運(yùn)動(dòng)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=(N1+N2)·(LC+LB),LC·Fs=Nbr·(LC+LB)。因?yàn)镹1≈N2，我們要求N1+N2

19、>Nbr以使空心管運(yùn)動(dòng)，這就意味著LB>LC這個(gè)條件應(yīng)該滿足。因?yàn)槿绻鸏C=0，空心管不能運(yùn)動(dòng)，那么運(yùn)動(dòng)范圍最終由0<LC<LB決定。在我們的設(shè)計(jì)中，LC+LB≈30mm（壓電掃描管的長(zhǎng)度），我們期望方形空心管的最大位移小于15mm。如果夾持彈簧鏈接到藍(lán)色環(huán)（不是空心管），移動(dòng)范圍上的這個(gè)問(wèn)題的限制任然是可以解決的。</p><p>　　圖4 圖示可得運(yùn)動(dòng)范圍大小</p>&

20、lt;p><b>　　性能測(cè)試</b></p><p>　　我們?cè)谑覝叵?，在移?dòng)方向（向上移動(dòng)和向下移動(dòng)）的極端條件下測(cè)試了電機(jī)的運(yùn)行情況，包括它的步長(zhǎng)，速度，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N1≈N2≈Nbr≈0.22N，這個(gè)值遠(yuǎn)遠(yuǎn)小于驅(qū)動(dòng)壓電P1和P2的阻力值（

21、Fbl1～Fbl2～2N）。</p><p>　　最大步長(zhǎng)是12.9μm，測(cè)試條件是：0.3Hz向下滑的驅(qū)動(dòng)頻率帶動(dòng)的圓形空心管。當(dāng)移動(dòng)方向變?yōu)橄蛏系臅r(shí)候，步長(zhǎng)因?yàn)橹亓ψ優(yōu)?1.7μm。如果是方形空心管，向下的步長(zhǎng)和向上的步長(zhǎng)分別是8.9μm和8.2μm，這個(gè)值更為合適，因?yàn)樗那懈钸吘壟c藍(lán)色環(huán)相接。所有這些步長(zhǎng)值都比其他類似大小的壓電電機(jī)9,11,23的步長(zhǎng)要大。電機(jī)的轉(zhuǎn)速當(dāng)然和驅(qū)動(dòng)頻率很接近。我們?cè)O(shè)置的最大驅(qū)

22、動(dòng)頻率是50Hz，圓形空心管（向上運(yùn)行對(duì)向下運(yùn)行）和方形空心管（向上運(yùn)行對(duì)向下運(yùn)行）的轉(zhuǎn)速分別是（22.27對(duì)24.62）（19.44對(duì)19.8）mm/min。</p><p>　　當(dāng)驅(qū)動(dòng)頻率上升或者工作電壓值下降的時(shí)候，步長(zhǎng)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(zhǎng)，但是我們更傾向于使用方形空心管，因?yàn)樗膬?yōu)點(diǎn)限制更少。例如，方形空心管的運(yùn)行范圍是9mm（理論上），而圓形空心管的運(yùn)行范圍

23、是3.3mm（比方形的在理論上少了6.6mm）。方形空心管電機(jī)的運(yùn)行曲線如圖6所示，比圓形空心管電機(jī)的曲線更平滑更穩(wěn)定。</p><p>　　雖然測(cè)試是在室溫條件下進(jìn)行的，但是電機(jī)在固化氮的溫度下工作也有很大潛力，原因有兩個(gè)：大步長(zhǎng)的特性可以應(yīng)對(duì)熱量下降帶來(lái)的問(wèn)題，保持運(yùn)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(zhǎng)，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(jí)的下滑，

24、確保必要的摩擦力關(guān)系的成立，|fr1|≈|fr2|≈|frbr|,這種變化對(duì)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(jì)。</p><p>　　方形空心管可以承受磨損和撕裂的問(wèn)題，因?yàn)樗乃膫€(gè)邊緣可以被藍(lán)色環(huán)固定。為了測(cè)試它的耐久度，我們?cè)?#177;200V和50Hz的驅(qū)動(dòng)電壓下超過(guò)一千次的3mm的替換條件下操作電機(jī)，電機(jī)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

25、的話）。</p><p>　　圖5 用圓形空心管測(cè)試的電機(jī)步長(zhǎng)（左側(cè)垂直軸）和速度（右側(cè)垂直軸）（a）頻率（最大工作電壓=±200V）（b）最大工作電壓（頻率=20Hz）</p><p>　　圖6 用圓形空心管測(cè)試的電機(jī)步長(zhǎng)（左側(cè)垂直軸）和速度（右側(cè)垂直軸）（a）頻率（最大工作電壓=±200V）（b）最大工作電壓（頻率=20Hz）</p><p

26、><b>　　結(jié)束語(yǔ)</b></p><p>　　我們呈現(xiàn)了一個(gè)強(qiáng)大的線性壓電電動(dòng)機(jī)，它擁有其他壓電電動(dòng)機(jī)不能同時(shí)具有的幾個(gè)重要特性，包括：大步長(zhǎng)，小尺寸，剛性，結(jié)構(gòu)簡(jiǎn)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(cè)試結(jié)果非常好。在建設(shè)一個(gè)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。</p><p><b>　　致謝</b&

27、gt;</p><p>　　這項(xiàng)工程得到了中國(guó)國(guó)家自然科學(xué)基金10627403號(hào)，中國(guó)國(guó)家強(qiáng)磁場(chǎng)設(shè)施計(jì)劃和中國(guó)科學(xué)院自然科學(xué)基金YZ200846的資助。</p><p><b>　　原文：</b></p><p>　　A simple, compact, and rigid piezoelectric step motor with large

28、 step size</p><p>　　Qi Wang1 and Qingyou Lu1,2,a</p><p>　　1Hefei National Laboratory for Physical Sciences at Microscale, University of Scienceand Technology of China, Hefei, Anhui 230026, Peopl

29、e’s Republic of China</p><p>　　2High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031,People’s Republic of China</p><p>　　Received 11 June 2009; accepted 16 July 2009;

30、 published online 14 August 2009</p><p>　　We present a novel piezoelectric stepper motor featuring high compactness, rigidity, simplicity, andany direction operability. Although tested in room temperature, i

31、t 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

32、a hollow shaft inside at both ends via the spring parts of the shaft. Two driving voltages that singly deform the t</p><p>　　DOI: 10.1063/1.3197381</p><p>　　I. INTRODUCTION</p><p>　

33、　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<

34、/p><p>　　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 m

35、odern optics12 and cell or DNA manipulations.13</p><p>　　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

36、,24 and inertial slider,4,25–28 etc.However, they all have severe drawbacks. For the ?rst three</p><p>　　types, each needs three or more piezoelectric actuators to operate, which is too complicated in both s

37、tructure 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

38、vibration, thus downgrading the quality of atomic images)and unable to produce enough pushing force.</p><p>　　In this paper, we demonstrate a piezoelectric motor that does not have the above limitations. It

39、is implemented by a single piezoelectric scanner tube(PST) that is axially and deeply cut into almost two halves and grips a hollow shaft</p><p>　　(HS)inside from both ends by the spring parts of the HS.Two

40、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

41、large step</p><p>　　size make it particularly useful in small space(extreme conditions)and low temperature applications.</p><p>　　II. DESIGN AND PRINCIPLE</p><p>　　Figure 1 shows th

42、e 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</p>

43、<p>　　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

44、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 othe

45、r is cut into two semi rings which are called clamping semi rings(will clamp </p><p>　　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 circu

46、lar 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 w

47、ire 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 entir</p><p>　　FIG.1.(a)The structure of our piezomo

48、tor;(b)two kinds of hollow shafts</p><p><b>　　studied.</b></p><p>　　One big advantage of this mutual clamping between the PST and HS at both ends is that this structure is very ?rm(r

49、esistant 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

50、 the three maximum static frictions remains equal in value.</p><p>　　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

51、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 wh

52、ile 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, becaus</p><p>　　Finally, P1 and P2 return to the initial states and the

53、 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.</p>

54、;<p>　　FIG.2.The photo of our piezoelectric motor.</p><p>　　FIG. 3.(a)The two driving voltages which move the HS in the expansion</p><p>　　direction of the PST.(b)The two driving voltages

55、 which move the HS in the</p><p>　　contraction direction of the PST.</p><p>　　Apart from the circular HS described above, we have also tried a square HS (42 mm long by 5.6 mm wide, wall thicknes

56、s 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 cutti

57、ng 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</p><p>　　FIG.4.The schematic diagram for d

58、eriving the range of motion.</p><p>　　Apparently, the clamping forces N1,N2,and Nbr do not remain constant when the HS moves, thus limiting its range of motion.The range of motion for the square HS can be de

59、rived as follows. Referring to Fig.4 in which FS is the force produced by the spring and LB and LC stand for the distances from the spring to the base ring and to the clamping semi rings, respectively, the lever law lead

60、s to:LB·FS=(N1+N2)·(LC+LB) and LC·FS=Nbr·(LC+LB).Because N1=N2 and we need N1+N2>Nbr for the HS to walk, this m</p><p>　　III. PERFORMANCE TEST</p><p>　　We have tested the

61、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, re

62、spectively]and operating voltage[Figs.5(b)and 6(b)for circular and square HS, respectively]. The pressing forces were set to N1≈N2≈Nbr≈0.22N for circular HS which are much smaller than the blocking forces (Fbl1～Fbl2～2N)o

63、f the driving piezo-P1 and P2.</p><p>　　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 direction is chang

64、ed 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 sapphi

65、re rings. All these step sizes are rather large compared with other types of piezoelectric motors9,11,23 with the</p><p>　　When the driving frequency increases or if the magnitude of the operating voltage dr

66、ops, 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 sq

67、uare 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 m</p><p>　　F

68、IG.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 H

69、z).</p><p>　　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

70、with remarkable step size remaining to produce a move;(2)its spring clamping structure validates the required friction relationship,|fr1|≈|fr2|≈|frbr|,in a very wide temperature range since a change from room temperature

71、 to liquid helium only shrinks the compression springs (～5 mm long, spring constant is</p><p>　　The square HS may suffer wear and tear issues as its four edges could be scratched by the sapphire rings. To te

72、st 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

73、 course, the HS can be coated with wear resistant materials for better protection if necessary.</p><p>　　FIG.6.The step size(left vertical axis)nd speed(right vertical axis of the motor using the circular HS

74、 as functions of (a) frequency(maximum operating voltage=±200 V) and (b) maximum operating voltage(frequency=20Hz).</p><p>　　IV. CONCLUSION</p><p>　　We have presented a powerful linear piez

75、oelectric 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