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0496-60mm旋轉(zhuǎn)行波超聲電機(jī)設(shè)計及工藝【優(yōu)秀含6張CAD圖+說明書+工藝卡】,優(yōu)秀含6張CAD圖+說明書+工藝卡,60,mm,妹妹,旋轉(zhuǎn),行波,超聲,電機(jī),機(jī)電,設(shè)計,工藝,優(yōu)秀,優(yōu)良,cad,說明書,仿單
一、選題的依據(jù)及意義
在當(dāng)今21世紀(jì),隨著電子信息技術(shù)的不斷發(fā)展和計算機(jī)的廣泛應(yīng)用。控制技術(shù)同樣也得到迅猛的發(fā)展。在當(dāng)前的控制技術(shù)中,必然有一個實現(xiàn)驅(qū)動和控制的微電機(jī)伺服系統(tǒng),這個系統(tǒng)很大程度上決定了系統(tǒng)整體性能的好與壞。為了使微電機(jī)伺服系統(tǒng)達(dá)到靈活性、快速性、簡便性控制的要求,多年以來,國內(nèi)外的科技界和工業(yè)界一直致力于研究各種新型微型電機(jī)。其中,性能卓越的超聲波電機(jī)利用壓電陶瓷逆壓電效應(yīng)產(chǎn)生超聲振動,并將這種振動通過摩擦耦合來直接驅(qū)動轉(zhuǎn)子和滑塊的旋轉(zhuǎn)。這種直接用于驅(qū)動的電機(jī)從20世紀(jì)80年代以來就深受世界各國科研工作者的青睞。現(xiàn)已成為機(jī)電控制領(lǐng)域的研究熱點。
這種電機(jī)打破了傳統(tǒng)的電機(jī)概念,不是通過電場的相互作用將電能轉(zhuǎn)換成機(jī)械能,沒有電磁繞組和磁路,不以電磁的相互作用傳遞能量。而是利用電能產(chǎn)生超聲振動獲得驅(qū)動力,通過摩擦耦合將動力轉(zhuǎn)換成轉(zhuǎn)子或滑塊的運(yùn)動。相對于傳統(tǒng)的電機(jī)而言,它慣性小、響應(yīng)快、可控制性好、不受磁場影響、同時本身也不產(chǎn)生磁場、定位精度高等特點。它還具有重量輕、結(jié)構(gòu)簡單、效率高、噪音小、低速大轉(zhuǎn)矩、可直接驅(qū)動負(fù)載等特性。由于直接驅(qū)動負(fù)載,避免了使用齒輪變速而產(chǎn)生的振動噪音、間隙以及低效率、難控制等一些問題。所以說,超聲電機(jī)是一種全新的自動控制執(zhí)行元件,也是一種嶄新的傳統(tǒng)的傳動模式,是對傳統(tǒng)電磁驅(qū)動原理的突破和有力的補(bǔ)充。
超聲電機(jī)可采用不同的振動模式來產(chǎn)生驅(qū)動力,因而可研制出多種不同的超聲電機(jī),包括駐波型、行波型,其中又包括直線型、旋轉(zhuǎn)型、縱向振動型、縱-扭復(fù)合型等。而旋轉(zhuǎn)型行波超聲電機(jī)是所有類型中結(jié)構(gòu)較簡單、用途最廣泛的一種,也是最有發(fā)展前景的一種。
從超聲電機(jī)的發(fā)展歷史來看,在1942年,美國的Williams和Brown就提出了超聲電機(jī)的原始思想。1982年,日本科學(xué)家指田年生成功研制了行波超聲電機(jī)。這標(biāo)志著超聲電機(jī)應(yīng)用到了實際的生產(chǎn)生活中。經(jīng)過這四十年里的努力,完成了從設(shè)想到現(xiàn)實的轉(zhuǎn)變。在當(dāng)今這個社會,超聲電機(jī)的應(yīng)用涉及到航空、航天、汽車制造、生物工程、化工、醫(yī)學(xué)等領(lǐng)域。具體有照相機(jī)的鏡頭調(diào)焦、驅(qū)動裝置的精確定位、閥門控制、機(jī)器人關(guān)節(jié)的驅(qū)動、核磁共振裝置中的應(yīng)用等方面。正是因為超聲電機(jī)的獨特特點,它可廣泛用于機(jī)器人、微型機(jī)械的驅(qū)動、精密儀器的驅(qū)動、強(qiáng)磁場環(huán)境下設(shè)備驅(qū)動裝置等。據(jù)有關(guān)專家預(yù)測:隨著超聲波電機(jī)的卓越性能日益被人們認(rèn)識和采用,它將在較大程度上替代小型電磁微型電機(jī)。同時,超聲波電機(jī)的推廣應(yīng)用和它的驅(qū)動控制技術(shù)密不可分的,只有結(jié)合有效的控制方法和控制策略,才能發(fā)揮超聲波電機(jī)的卓越性能。
對于超聲電機(jī)的研究與開發(fā),將不斷完善電機(jī)方面的理論知識和豐富電機(jī)的產(chǎn)品的類型,并極大地促進(jìn)工業(yè)智能化、自動化的發(fā)展。將取代傳統(tǒng)的小型或微型電機(jī)。并能夠在上述領(lǐng)域得到廣泛的應(yīng)用,并促進(jìn)該領(lǐng)域的技術(shù)革新。因此,對超聲電機(jī)的研究有著非常重要的科學(xué)意義,同時還有廣泛的應(yīng)用的前景和良好的實用價值。
二、國內(nèi)外研究概況及發(fā)展趨勢(含文獻(xiàn)綜述)
超聲波電機(jī)是國內(nèi)外日益受到重視的一種新型直接驅(qū)動電機(jī)。與傳統(tǒng)的電磁式電機(jī)不同,超聲波電機(jī)沒有磁極和繞組,不依靠電磁介質(zhì)來傳遞能量,而是利用壓電陶瓷的逆壓電效應(yīng),通過各種伸縮振動模式的轉(zhuǎn)換與耦合,將材料的微觀變形通過共振放大和摩擦耦合轉(zhuǎn)換成轉(zhuǎn)子或者滑塊的宏觀運(yùn)動。在其研究和發(fā)展過程中,曾有很多不同的命名,如振動電機(jī)、壓電電機(jī)、聲表面波電機(jī)、超聲馬達(dá)等,現(xiàn)在國內(nèi)比較常用的稱謂是超聲電機(jī)或超聲電機(jī)。超聲波電機(jī)具有功率密度大、無電磁干擾、低速大轉(zhuǎn)矩、動作響應(yīng)大、運(yùn)作無噪聲、無輸入自鎖等卓越特性,在非線形運(yùn)動領(lǐng)域要比傳統(tǒng)的電磁電機(jī)性能優(yōu)越得多。超聲波電機(jī)在工業(yè)控制系統(tǒng)、啟齒專用電器、超高精度測量儀器、辦公自動化設(shè)備、智能機(jī)器人等領(lǐng)域有著十分廣闊的應(yīng)用前景,近年來備受科技界和工業(yè)街的重視,是當(dāng)前非連續(xù)驅(qū)動控制領(lǐng)域的一個研究熱點。
1.超聲波電機(jī)的國外研究
日本的超聲波電機(jī)及其驅(qū)動控制的產(chǎn)業(yè)化應(yīng)用處于世界領(lǐng)先的地位,它掌握著世界上大多數(shù)的超聲波電機(jī)的制造與控制技術(shù)的發(fā)明專利,幾乎所有的知名大學(xué)和研究所都在進(jìn)行研究,如東京大學(xué)、東京工業(yè)大學(xué)、東京農(nóng)工大學(xué)、山形大學(xué)等都至少有一個屬于本校的超聲波電機(jī)研究小組,或進(jìn)行理論分析研究、或進(jìn)行新原理、新結(jié)構(gòu)的超聲電機(jī)的研究、或進(jìn)行超聲波電機(jī)控制專用芯片的集成。日本參與研發(fā)、商業(yè)制造及銷售的大公司更多,如佳能公司、新生公司、本多公司、松下公司、美能達(dá)公司、尼康公司精工和NEC公司等。近10年,日本的超聲波電機(jī)進(jìn)入了實用化的商業(yè)應(yīng)用階段。
由于日本在超聲波電機(jī)及驅(qū)動控制領(lǐng)域所獲得的極大成功和較高的商業(yè)利潤,美、英、法、德等國不甘落后,緊隨日本之后,各自在相關(guān)的超聲波電機(jī)及其驅(qū)動控制、新結(jié)構(gòu)、新原理、新的應(yīng)用領(lǐng)域等方面取的了一定的研究成果。
美國的密蘇里大學(xué)(Missour-Rolla)主要從事電機(jī)工作時定子與轉(zhuǎn)子之間的接觸模型以及接觸力對電機(jī)壽命影響的研究,并同Allied Signal Aerospace公司合作進(jìn)行行波超聲波電機(jī)加工工藝及其控制技術(shù)的研究。MIT的航空航天系和人工智能中心研制出直徑僅為2mm的超聲馬達(dá),還開發(fā)了具有雙齒面的行波型超聲馬達(dá)。同時與美國國家航空宇航局(NASA)的噴氣推進(jìn)實驗室、材料研究室共同研究開發(fā)了用于火星探測器操作臂關(guān)節(jié)驅(qū)動的大力矩超聲波電機(jī)。
英國的伯明翰大學(xué)(Birmingham)主要從事基于“諧波齒”理論的超聲波電機(jī)的研究,以及實現(xiàn)超聲波電機(jī)高精度的定位控制、探索開環(huán)的可控性等研究。
德國Paderborn大學(xué)的J.Wallaschek所領(lǐng)導(dǎo)的科研小組主要從事超聲波電機(jī)振動分析和動態(tài)接觸等方面的研究,如:線性、旋轉(zhuǎn)行波電機(jī)的振動分析和動態(tài)接觸問題,電機(jī)的線性和非線性振動穩(wěn)定性問題,電機(jī)運(yùn)動的控制問題,復(fù)合材料的動態(tài)特性以及結(jié)構(gòu)的阻抗匹配研究等。
法國的Cedrat Recherche研究所借助光學(xué)干涉儀及電測量的方法,對所研究的線性電機(jī)定子的切線振動位移、法線位移、切線振動速度、法線力因子做了系統(tǒng)的測試和評估。另外,還有許多國家陸續(xù)參與到研究超聲波電機(jī)及其驅(qū)動控制技術(shù)的研究中來。但是,目前大多數(shù)其他國家主要側(cè)重于驅(qū)動控制技術(shù)的研究和實際應(yīng)用。
2.超聲波電機(jī)國內(nèi)得研究現(xiàn)狀
國外超聲波電機(jī)獲得成功應(yīng)用被多次報道,因而在20世紀(jì)的80年代末期到90年代的初獲得我國科學(xué)工作者得關(guān)注。雖然我國超聲波電機(jī)及其驅(qū)動控制技術(shù)得研究起步較晚,但發(fā)展迅速。
1986~1990年間,四川壓電與聲光技術(shù)研究所得劉大春、劉一聲等人將日本得有關(guān)超聲波電機(jī)得研究情況陸續(xù)介紹到國內(nèi)。
進(jìn)入20世紀(jì)90年代以來,隨著國內(nèi)得科研人員從國外學(xué)成回國,國內(nèi)的超聲波電機(jī)得試制工作逐步進(jìn)入正軌,國內(nèi)除了東南大學(xué)外,有多個高校加入到超聲波電機(jī)的研究行列,主要有清華大學(xué)、南京航空航天大學(xué)、浙江大學(xué)、哈爾濱工業(yè)大學(xué)等國內(nèi)著名高校,還有中科院、電子工業(yè)部21所、長春光機(jī)所等科研院所,對典型的幾種超聲波電機(jī)的運(yùn)行原理、數(shù)學(xué)建模、仿真計算、樣機(jī)制作、驅(qū)動技術(shù)及惡劣測試等進(jìn)行研究,并取得一大批的研究成果?,F(xiàn)在國內(nèi)有《壓電與聲光》、《現(xiàn)代科技譯叢》、《國際科技消息》、《微電機(jī)》等刊物介紹超聲波電機(jī)。
東南大學(xué)研制的系列行波型、步進(jìn)型和柱狀夾心式超聲波電機(jī)樣機(jī)水平已接近使用要求,直徑為100㎜的均壓行超聲波電機(jī)及超聲波電機(jī)多功能驅(qū)動控制裝置分別獲得國家專利;南京航天航空大學(xué)研制出多種結(jié)構(gòu)型式的樣機(jī),如環(huán)形行波型超聲波電機(jī)、雙面齒型、圓板型、駐波型超聲波電機(jī);清華大學(xué)則研究了目前國內(nèi)直徑最?。?㎜)的超聲波電機(jī),有望在心臟的微循環(huán)系統(tǒng)中應(yīng)用,環(huán)形中空用超聲波電機(jī)的樣機(jī)已進(jìn)行優(yōu)化設(shè)計;浙江大學(xué)研制了大力矩和高重復(fù)定位精度的縱扭復(fù)合型超聲波電機(jī);華中科技大學(xué)研制了大扭矩行波型超聲波電機(jī)并對轉(zhuǎn)子尺寸和形狀對輸出功率和輸入轉(zhuǎn)矩得影響作了深入的研究。國內(nèi)所研制的超聲波電機(jī)已接近實用要求并渴望逐步實現(xiàn)批量生產(chǎn),有些擬用于軍工的導(dǎo)彈引導(dǎo)裝置,有些電機(jī)的產(chǎn)業(yè)化應(yīng)用前景被國內(nèi)大型企業(yè)和傳統(tǒng)電機(jī)生產(chǎn)廠家看好。
三、研究內(nèi)容
設(shè)計一臺直徑為60mm的板式旋轉(zhuǎn)行波超聲電機(jī),要求
(1) 定子外徑為60mm,工作振動模態(tài)為B09,模態(tài)頻率在 kHz之間;
(2)額定轉(zhuǎn)矩0.5 Nm,堵轉(zhuǎn)力矩0.8 Nm,最大輸出功率3W;
(3)額定轉(zhuǎn)速50 r/min,轉(zhuǎn)速范圍10~100 r/min;
(4)質(zhì)量m300g,外觀尺寸l×b×h≤70mm×70mm×30mm;
(5)工作溫度T,適應(yīng)環(huán)境溫度為-25 oC~55 oC;
(6)啟、停響應(yīng)時間ts;
(7)工作電壓為130 Vrms。
四、研究方案(技術(shù)路線)及及優(yōu)化方案
根據(jù)需求,提出性能指標(biāo)
初步確定定子的機(jī)構(gòu)
對定子進(jìn)行動態(tài)分析
工作頻率是否合適
是否無模態(tài)混疊
合理設(shè)計轉(zhuǎn)子
仿真結(jié)果是否滿足
性能指標(biāo)
電機(jī)性能仿真
試制實驗
電機(jī)性能是否滿足
性能指標(biāo)
編寫技術(shù)資料,進(jìn)行投產(chǎn)
●研究路線:
●優(yōu)化方案:
在超聲波電機(jī)的定子固定頻率和工作模態(tài)的計算方面,利用解析法和有限元分析理論進(jìn)行求解,并結(jié)合ANSYS有限元分析軟件進(jìn)行模擬仿真。
五、目標(biāo)、主要特色及工作進(jìn)度
l 目標(biāo):
通過超聲電機(jī)中定子與轉(zhuǎn)子設(shè)計和其他相關(guān)方面的研究,設(shè)計出來一臺符合要求的超聲電機(jī)。
l 主要特色:
超聲電機(jī)一種具有全新原理和結(jié)構(gòu)的新概念電-機(jī)能量轉(zhuǎn)換裝置超聲電機(jī)利用壓電材料(通常是壓電陶瓷)的逆壓電效應(yīng),借助于定子彈性體的彈性諧振作用把電能轉(zhuǎn)換為微米級幅度的機(jī)械振動,再通過定子與轉(zhuǎn)子(或動子)之間的界面接觸過程和摩擦作用把定子的微幅振動轉(zhuǎn)換為便于為人們利用的轉(zhuǎn)子(或動子)的宏觀轉(zhuǎn)動(或直線運(yùn)動),并在這個過程中實現(xiàn)電能到機(jī)械能的轉(zhuǎn)換。
l 工作進(jìn)度:
1. 查閱相關(guān)資料,外文資料翻譯(6000字符以上),撰寫開題報告。
第1周—第2周
3. 初定定子的結(jié)構(gòu)尺寸,選定定子工作模態(tài); 第3周—第4周
4. 電機(jī)主要部件(定子、轉(zhuǎn)子)的設(shè)計與計算; 第5周—第8周
5. 繪制電機(jī)的裝配圖及其各零件工作圖; 第9周—第12周
6. 定子加工的工藝編制; 第13周
7. 撰寫畢業(yè)論文; 第14周—第16周
7. 答辯準(zhǔn)備及畢業(yè)答辯。 第17周
六、參考文獻(xiàn)
[1] 胡敏強(qiáng),金龍. 超聲波電機(jī)的原理與設(shè)計,北京:科學(xué)出版社,2005
[2] 趙淳生. 超聲波電機(jī)技術(shù)及其應(yīng)用,北京:科學(xué)技術(shù)出版社,2007
[3] 尹燕麗. 超聲馬達(dá)及其驅(qū)動控制系統(tǒng). 洛陽工學(xué)院碩士學(xué)位論文,2004
[4] 賀紅林. 超聲電機(jī)及其在機(jī)器人上的應(yīng)用研究. 南京航空航天大學(xué)博士學(xué)位論文,2006.11
[5] 石斌. 環(huán)形行波超聲馬達(dá)及其驅(qū)動控制的研究. 東南大學(xué)博士學(xué)位論文,2001
[6] 上羽貞行,富川義朗. 超聲波馬達(dá)理論與應(yīng)用.上海:上海科技出版社,1998
[7] 趙淳生. 21世紀(jì)超聲電機(jī)技術(shù)與展望. 振動、測試與診斷,2000.1
[8] 陳永校,郭吉豐. 超聲波電動機(jī). 杭州:浙江大學(xué)出版社,1994
[9] 胡敏強(qiáng).超聲電動機(jī)的研究及其應(yīng)用。微特電機(jī),2000,(5):8-24
[10] 趙淳生,李朝東.日本超聲電機(jī)的產(chǎn)業(yè)化,應(yīng)用和發(fā)展.振動,測試與診斷,1999,19(1):1-7
[11] Heiner Storck,Jorg wallaschek. The effect of tangential elasticity of the contact layer between stator and rotor in traveling wave ultrasonic motors. Int. journal of non-linear Mechanics 2003(38):143-159
[12] J.L Pons,H.Rodriguea,M.Villegas,et al. Parametrical optimization of ultrasonic motors. Sensor and Actuator ,2003 A 107:169-182
[13] A. M. Flynn, et al. Piezoelectric micromotors for microrobots. J. of MEMS, 1992,1(1): 44-51.
旋轉(zhuǎn)型行波超聲電機(jī)
帕薩迪納,CA91109,加利福尼亞理工學(xué)院噴氣推進(jìn)實驗室;
科斯塔梅薩,CA92627,材料質(zhì)量檢測中心,威廉梅蘭迪亞。
摘要:旋轉(zhuǎn)型超聲波電機(jī)逐漸發(fā)展為太空飛船的微型驅(qū)動器及其子系統(tǒng)。此技術(shù)應(yīng)用于有著嚴(yán)格要求的商業(yè)產(chǎn)品中,為了更加有效地設(shè)計此類電機(jī)而采用分析工具。分析模型用于檢測在旋轉(zhuǎn)超聲電機(jī)中激勵產(chǎn)生的彎曲行波。這個有限元分析模型為環(huán)形,被用于預(yù)測環(huán)形定子的振動頻率和模態(tài)響應(yīng)。此模型給設(shè)計高效率的超聲波電機(jī)提供依據(jù),定子的設(shè)計包括齒槽、壓電體、定子的幾何外形等方面,定子是由他們有機(jī)地組合而成。理論計算值與實驗結(jié)果的比較表明這將是一個值得世人所關(guān)注的課題。與此同時,超聲波電機(jī)還被用于機(jī)械臂,他們是否能夠在火星的環(huán)境下正常運(yùn)行的研究還在進(jìn)行中。
關(guān)鍵詞:驅(qū)動器,彈性體,壓電電機(jī),超聲波電機(jī),定子與轉(zhuǎn)子,模態(tài)分析。
2. 緒論
當(dāng)前,美國國家航空和宇宙航行局一直致力于縮小未來太空飛船的體積和減少其質(zhì)量的研究。為了與這變化想適應(yīng),超聲波電機(jī)逐漸成為機(jī)械裝置簡化的一個重要的手段。傳統(tǒng)的微型電磁式電機(jī)由于受制造工藝的限制,一般這類電機(jī)為了達(dá)到速度與扭矩相適應(yīng)需要使用齒輪減速機(jī)構(gòu),采用這個將會增加設(shè)備的質(zhì)量、體積和機(jī)構(gòu)的復(fù)雜性,同時增加系統(tǒng)的部件也會降低系統(tǒng)的可靠度?,F(xiàn)在所介紹的旋轉(zhuǎn)壓電電機(jī)將是微型設(shè)備中的未來潛在驅(qū)動裝置,這種馬達(dá)具有低速大轉(zhuǎn)矩,堵轉(zhuǎn)力矩高、結(jié)構(gòu)簡單、響應(yīng)快等特點,可以將外形制成環(huán)形(應(yīng)用于光學(xué),配線通過中心的電子儀表組件)。目前,一個關(guān)于超聲波電機(jī)在宇宙環(huán)境中工作情況的課題正在研究中,換句話說,它能夠在低溫和真空的環(huán)境下有效可靠地運(yùn)行。
超聲波電機(jī)按工作模式劃分,可以分為靜態(tài)和動態(tài)兩種;按運(yùn)動方式可以分為旋轉(zhuǎn)式和直線式兩種;按執(zhí)行機(jī)構(gòu)的形狀可以分為梁式、桿式和板式等等。盡管它們之間有區(qū)別,但是他們的工作原理都是一樣,即利用壓電效應(yīng)產(chǎn)生的激勵:彈性體(通常與壓電陶瓷結(jié)合)的細(xì)小變形通過精確靜態(tài)機(jī)構(gòu)或者動態(tài)諧振的方法擴(kuò)大。一些超聲波馬達(dá)已經(jīng)在一些要求結(jié)構(gòu)緊湊和做間歇運(yùn)動的領(lǐng)域進(jìn)行產(chǎn)業(yè)化應(yīng)用。這些應(yīng)用包括:照相機(jī)的鏡頭自動調(diào)焦、手表馬達(dá)以及結(jié)構(gòu)緊湊的打字機(jī)。傳統(tǒng)電磁電機(jī)為了得到和超聲波電機(jī)一樣轉(zhuǎn)矩—速度特性,需要添加齒輪減速機(jī)構(gòu),因此增加電機(jī)的尺寸、質(zhì)量和傳動裝置的復(fù)雜性。超聲波電機(jī)有高的自鎖力,它能提供精確的零位移。此外,由于這些電機(jī)是依靠摩擦力矩驅(qū)動的,所以在無外力的作用下產(chǎn)生反驅(qū)動,因此讓人關(guān)注的與其他電機(jī)相比更高的堵轉(zhuǎn)扭矩。電機(jī)的組成部件的數(shù)量少代表了潛在故障點的數(shù)目會相應(yīng)減少。超聲波電機(jī)的優(yōu)良特性被人們所看好,將其應(yīng)用于有著體積小,間歇運(yùn)動要求的機(jī)器人上。
圖1為超聲波電機(jī)(環(huán)形行波超聲波電機(jī))的工作原理。行波形成于由環(huán)形彈性體構(gòu)成的定子的表面上,并在轉(zhuǎn)子的表面產(chǎn)生橢圓運(yùn)動。 定子表面質(zhì)點的橢圓運(yùn)動驅(qū)動轉(zhuǎn)子和與之相聯(lián)的軸旋轉(zhuǎn)。在定子表面添加齒槽結(jié)構(gòu)是用于增大振動幅度,以此提高電機(jī)的轉(zhuǎn)速。超聲波電機(jī)的運(yùn)轉(zhuǎn)依靠運(yùn)動的定子和轉(zhuǎn)子之間的接觸面產(chǎn)生的摩擦。這也是設(shè)計如何延長接觸面的使用壽命的關(guān)鍵問題。
圖1 旋轉(zhuǎn)型行波超聲波電機(jī)工作原理示意圖
3. 工作原理
超聲波電機(jī)一般的工作原理是通過擴(kuò)大和重復(fù)振子的細(xì)小應(yīng)變來產(chǎn)生總的機(jī)械運(yùn)動。振子引起與轉(zhuǎn)子相接觸的定子接觸面上的質(zhì)點產(chǎn)生一個軌跡運(yùn)動,和在轉(zhuǎn)子與定子之間的分界面產(chǎn)生的摩擦,以此擴(kuò)大微小運(yùn)動來產(chǎn)生定子的大運(yùn)動。這一結(jié)構(gòu)如圖1所示。振子是壓電陶瓷受到激勵在定子內(nèi)部產(chǎn)生行波,致使定子上的質(zhì)點做橢圓運(yùn)動。在置于定子之上的轉(zhuǎn)子上施加預(yù)緊力和旋轉(zhuǎn)的定子和轉(zhuǎn)子之間產(chǎn)生摩擦力,依靠這些擴(kuò)大接觸面上的細(xì)微應(yīng)變。此運(yùn)動的轉(zhuǎn)換過程與齒輪機(jī)構(gòu)類似,產(chǎn)生與行波頻率相比更低的旋轉(zhuǎn)速度。
定子的下層的厚度設(shè)為,在定子粘有一定厚度的一組壓電體,這些壓電體按照一定的順序和位置與定子的后表面結(jié)合,壓電陶瓷的厚度設(shè)為??偤穸葹?,這是壓電陶瓷的厚度與定子的厚度之和(其中粘結(jié)層厚度忽略不計)。整體高度可以隨著徑向位置變化而變化。定子的外半徑為,內(nèi)孔半徑為。為了產(chǎn)生行波,由兩個相差四分之一的波長信號構(gòu)成壓電陶瓷的極化方向,這樣的極化方式也能被用來消除定子的范圍和最大撓曲。定子上的齒槽在徑向位置上成環(huán)形分布。
為了在定子內(nèi)部產(chǎn)生行波,需要同時激勵出兩個相同的正交振型。在同一模式中,兩個極化節(jié)粘于定子上,以此構(gòu)成由壓電驅(qū)動器,這就是模型。從幾何學(xué)上分析這個模型,結(jié)果表明激勵出兩個狀態(tài)分別為和信號,將會產(chǎn)生頻率為的行波。同時,通過改變驅(qū)動信號的工作狀態(tài),行波的方向也會相應(yīng)地發(fā)現(xiàn)變化。
4. 理論模型
超聲波電機(jī)的運(yùn)動方程源于漢密爾頓原理,這個分析模型被許多學(xué)者所推導(dǎo)過(比如Hagood、A. McFarland和Kagawa等)。定子的通用運(yùn)動方程歸納如下:
式中,[M]、[C]、[K]、[P]、[G]分別為質(zhì)量矩陣、阻尼矩陣、剛度矩陣、機(jī)電耦合矩陣和電容矩陣,矢量{x}、{j}、{}、{}和{Q}分別是模型的振幅、電勢正常外力向量、切向力矢量和電荷矢量。振幅矢量{x}和其他廣義矢量能夠通過能量平衡原理定義,如Rayleigh Ritz 原理。但是,這個方法忽略了定子上的齒槽的作用。環(huán)形定子也會隨著內(nèi)支撐板徑向位置的變化而變化,這可能會導(dǎo)致不合要求的結(jié)果出現(xiàn)。即使三維有限元分析方法(FEM)可以精確預(yù)測模型的固有頻率和定子的瞬態(tài)響應(yīng)特性,但這是一個復(fù)雜的計算過程。此外,決定設(shè)計模型往往需要通過三維有限元分析軟件核實計算響應(yīng)模型和共振頻率。由于此方法的所提及的缺點,需要改進(jìn)過去所描述的周期性有限元,這也是基于超聲波馬達(dá)的對稱特性。環(huán)形有限元如圖2所示,其中都是自由度。橫向移動量穿過每個部分,其表現(xiàn)方程如下:
式中,表示徑向振動頻率,指標(biāo)m、n分別是沿著q和r方向的模型。當(dāng)假設(shè)橫向切力和旋轉(zhuǎn)慣性效應(yīng)忽略不計,質(zhì)量和剛度矩陣能按照標(biāo)準(zhǔn)變化理論推導(dǎo)。因此,解決特征值問題可以得到正常頻率和模型的外形。
用標(biāo)準(zhǔn)的公式表示,其中包括了定子齒槽的作用。其他廣義坐標(biāo)的制定細(xì)節(jié)也和這些類似確定。這些將會在作者以后的出版物中提及。
5. 對壓電電機(jī)的分析
對非線性、定子—轉(zhuǎn)子之間的動態(tài)聯(lián)接模型分析時,主要討論的內(nèi)容包括預(yù)測電機(jī)的潛在穩(wěn)定狀態(tài)和在臨界設(shè)計參數(shù)的情況下電機(jī)的運(yùn)行瞬態(tài)性能,比如接觸面上的法向力、齒高、定子的徑向切面。有限元的運(yùn)算法則被融入分析軟件中,MATLAB的代碼被用于確定定子模型的特征。模型反應(yīng)出定子的形狀、壓電陶瓷的極化模式和定子齒的相關(guān)參數(shù)。一旦選定定子的每個細(xì)節(jié),那么模型的響應(yīng)也確定了。這也可以在電腦中進(jìn)行實時監(jiān)測,如圖2所示,此時的模型中的參數(shù)已經(jīng)給定,(m,n)=(4,0)。利用電子點模式的干涉測量儀驗證預(yù)測的模型響應(yīng)特性,結(jié)果非常直觀,如圖3(左)。
MATLAB成為觀察超聲波電機(jī)工作狀態(tài)一種新的工具,能夠在電腦上模擬仿真。該軟件能夠模擬旋轉(zhuǎn)電機(jī)中彎曲行波在定子中工作狀態(tài)(圖4)。
圖2 環(huán)形有限元分析模型
圖3 模態(tài)響應(yīng)和共振頻率(左圖)和實驗檢測(右圖)
采用有限元的分析模型,以此構(gòu)建馬達(dá)。表1為直徑為1.71英寸鋼結(jié)構(gòu)定子所預(yù)測的振型和精確的共振頻率。在此表中的結(jié)果顯示理論值和實際值相對吻合,為了
圖4 利用動畫展示超聲波馬達(dá)的工作原理。
定子以行波的形式運(yùn)動,轉(zhuǎn)子在定子的上面旋轉(zhuǎn)。
表1 一個超聲波馬達(dá)的共振頻率的理論值和實驗值
輸入方式
固定頻率
測量頻率
(m,n)
(KHz)
(KHz)
(4,0)
14.88
14.55
(5,0)
22.48
22.37
(6,0)
31.45
31.34
圖7 在溫度為與真空度為的環(huán)境下,
直徑為1.1英寸的超聲波電機(jī)的實驗檢測到的轉(zhuǎn)矩—速度曲線
檢測真空和低溫對馬達(dá)的影響。一個直徑為1.1英寸的超聲波馬達(dá)在一個低溫實驗室進(jìn)行測試,此實驗利用SATEC系統(tǒng),實驗測試轉(zhuǎn)矩與速度的曲線如圖7所示。結(jié)果表明在進(jìn)行伺服控制的馬達(dá)能夠在溫度低于和真空度為的環(huán)境下非常穩(wěn)定的運(yùn)行。這一結(jié)果是一個鼓勵,同時也意味著在未來決定超聲波馬達(dá)能否在火星的模擬環(huán)境下運(yùn)轉(zhuǎn)的研究中還有需要的工作要做。
6. 結(jié)論
有限元模型被用來分析超聲波電機(jī)的光譜響應(yīng),包括各式各樣的外形結(jié)構(gòu)和組成材料的超聲波電機(jī)。模態(tài)響應(yīng)和預(yù)測的共振情況可以利用實驗的方法確定,其中有光譜測量法和干涉分析法。此外,還有像MATLAB這類簡單的分析平臺的交互式用戶界面軟件分析超聲波電機(jī)的模態(tài)行為。同時還可以用于研究各種定子參數(shù)。
致謝
在此感謝MIT航空宇航研究中心的,Nesbitt .W .Hagood IV。感謝他在IRTWG項目的合作期間給我的幫助.本文中結(jié)果的原稿從行星靈巧的操作者的課題中獲得。這課題由Dr. Paul Schenker負(fù)責(zé),由加利福尼亞大學(xué)噴氣推進(jìn)實驗中心出資,同時與美國航天宇航局簽訂協(xié)議。Mr. David和Dr. Chuck Weisbin是TRIGW項目的負(fù)責(zé)人。
參考文獻(xiàn)
1. M. Hollerbach, I. W. Hunter and J. Ballantyne, "A Comparative Analysis of Actuator Technologies for Robotics." In Robotics Review 2, MIT Press, Edited by Khatib, Craig and Lozano-Perez (1991).
2. A. M. Flynn, et al "Piezoelectric Micromotors for Microrobots" J. of MEMS, Vol. 1, No. 1, (1992), pp. 44-51.
3. E. Inaba, et al, "Piezoelectric Ultrasonic Motor," Proceedings of the IEEE Ultrasonics 1987 Symposium, pp. 747-756, (1987).
4. J. Wallashek, "Piezoelectric Motors," J. of Intelligent Materials Systems and Structures, Vol. 6, (Jan. 1995), pp. 71-83.
5. N. W. Hagood and A. McFarland, "Modeling of a Piezoelectric Rotary Ultrasonic Motor," IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol. 42, No. 2, 1995 pp. 210-224.
6. K. Kagawa, T. Tsuchiya and T. Kataoka, "Finite Element Simulation of Dynamic Responses of Piezoelectric Actuators,", J. of Sound and Vibrations, Vol. 89 (4), 1996, pp. 519-538.
7. D. G. Gorman, "Natural Frequencies of Transverse Vibration of Polar Orthotropic Variable Thickness Annular Plates, " J. of Sound and Vibrations
7
60mm旋轉(zhuǎn)行波超聲電機(jī)設(shè)計及工藝
摘要:超聲電機(jī)是利用壓電陶瓷的逆壓電效應(yīng),激勵彈性體產(chǎn)生諧振作用,把電能轉(zhuǎn)換成微米級振幅的振動,再依靠定子和轉(zhuǎn)子之間產(chǎn)生的摩擦耦合將這細(xì)微振動擴(kuò)大為轉(zhuǎn)子及與之相聯(lián)的軸的旋轉(zhuǎn)運(yùn)動。與傳統(tǒng)電磁電機(jī)相比,具有質(zhì)量小、結(jié)構(gòu)簡單、效率高、噪音小、低速大轉(zhuǎn)矩和可以直接驅(qū)動負(fù)載等特點。在航空航天、精密儀器、生物醫(yī)學(xué)與許多重要領(lǐng)域等具有廣闊的應(yīng)用前景。
適應(yīng)于工程上對超聲電機(jī)的需要,本文設(shè)計了一種直徑為60mm旋轉(zhuǎn)型行波超聲電機(jī),主要完成了以下工作:
1. 總結(jié)分析了國內(nèi)超聲電機(jī)技術(shù)的現(xiàn)狀、發(fā)展及所存在的問題;
2. 闡釋了旋轉(zhuǎn)行波超聲電機(jī)的運(yùn)動機(jī)理;
3. 利用ANSYS軟件建立了超聲電機(jī)定子的數(shù)學(xué)模型,利用模型對定子的工作模態(tài)進(jìn)行分析并計算,確定了60mm直徑超聲電機(jī)的定子的工作模態(tài);
4. 完成了60mm直徑超聲電機(jī)的裝配圖和零件圖的設(shè)計;
5. 編制了定子的機(jī)加工工藝。
關(guān)鍵詞:超聲電機(jī) 模態(tài)分析 設(shè)計
The design of 60mm diameter plate type Rotary Ultrasonic Motor actuated by traveling flexural waves And Technology
Abstract: Ultrasonic Motor uses the effect of Piezoelectric from Piezoelectric ceramic, and it produce the effect of resonance excitation by the Active Materials. That the electrical energy transform to the micro-deformations. To propel the rotor and the drive shaft connected to it though the amplification of the micro-deformation of the active material that depends on friction at the interface between rotor and stator.The Ultrasonic Motor offer light mass, simply constructions, high torque density at low speed, low noise, efficient and actuate directly to the load. Ultrasonic motor in the aviation and aerospace, precision instruments, bio-medicine and a number of important areas has broad application prospects.
Projects adapted to the needs of the ultrasonic motor, In this paper, the design a 60mm diameter rotary traveling wave type ultrasonic motor, the main completed the following work:
1. Summary analysis of the domestic status of ultrasonic motor technology, development and the problems;
2. To explain the rotary traveling wave ultrasonic motor of the movement mechanism;
3. The use of ANSYS software, the establishment of a ultrasonic motor mathematical model, using the model of the work of the stator modal analysis and calculation to determine a 60mm diameter stator ultrasonic motor mode of work;
4. Completed a 60mm diameter ultrasonic motor assembly drawings and parts of the design plan;
5. Preparation of the stator of the machine process.
Signature of supervisor:
Key word: Ultrasonic Motor Modal Analysis Design
Rotary Ultrasonic Motors Actuated By Traveling Flexural Waves
Shyh-Shiuh Lih, Yoseph Bar-Cohen,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109yosi@jpl.nasa.gov and?Willem Grandia, Quality Material Inspection (QMI), Costa Mesa, CA 92627
1.ABSTRACT
Ultrasonic rotary motors are being developed as actuators for miniature spacecraft instruments and subsystems. The technology that has emerged in commercial products requires rigorous analytical tools for effective design of such motors. An analytical model was developed to examine the excitation of flexural plate wave traveling in a rotary piezoelectrically actuated motor. The model uses annular finite elements that are applied to predict the excitation frequency and modal response of the annular stator. This model allows to design efficient ultrasonic motors (USMs) and it incorporates the details of the stator which include the teeth, piezoelectric crystals, stator geometry, etc. The theoretical predictions and the experimental corroboration showed a remarkable agreement. Parallel to this effort, USMs are made and incorporated into a robotic arm and their capability to operate at the environment of Mars is being studied.?
Key Words: Actuators, Active Materials, Piezoelectric Motors, Ultrasonic Motors (USMs), Stators and Rotors, Modal Analysis.??
2. INTRODUCTION?
The recent NASA efforts to reduce the size and mass of future spacecraft are straining the specifications of actuation and articulation mechanisms that drive planetary instruments. The miniaturization of conventional electromagnetic motors is limited by manufacturing constrains. Generally, these type of motors compromise speed for torque using speed reducing gears. The use of gear adds mass, volume and complexity as well as reduces the system reliability due the increase in the number of the system components. The recent introduction of rotary piezoelectric motors is offering potential drive mechanisms for miniature instruments [1-5]. These motors offer high torque density at low speed, high holding torque, simple construction, can be made in annular shape (for optical application, electronic packaging and wiring through the center), and have a quick response. A study is underway to develop such motors for operation at space environment, namely, operate effectively and reliably at temperatures down to cryogenic levels and vacuum.
Ultrasonic motors [5] can be classified by their mode of operation (static or resonant), type of motion (rotary or linear) and shape of implementation (beam, rod, disk, etc.). Despite the distinctions, the fundamental principles of solid-state actuation tie them together: microscopic material deformations (usually associated with piezoelectric materials) are amplified through either quasi-static mechanical or dynamic/resonant means. Several of the motor classes have seen commercial application in areas needing compact, efficient, and intermittent motion. Such applications include: camera auto focus lenses, watch motors and compact paper handling. To obtain the levels of torque-speed characteristics of USMs using conventional motors requires adding a gear system to reduce the speed, thus increasing the size, mass and complexity of the drive mechanism. USMs are fundamentally designed to have a high holding force, providing effectively zero backlash. Further, since these motors are driven by friction the torque that would cause them to be backdriven at zero power is significantly higher than the stall torque. The number of components needed to construct the motor is small minimizing the number of potential failure points. The general characteristic of USMs makes them attractive for robotic applications where small, intermittent motions are required. ?
In Figure 1 the principle of operation of an ultrasonic motor (flexural traveling wave ring-type motor) is shown as an example. A traveling wave is established over the stator surface, which behaves as an elastic ring, and produces elliptical motion at the interface with the rotor. This elliptical motion of the contact surface propels the rotor and the drive-shaft connected to it. The teeth, which are attached to the stator, are intended to increase the moment arm to amplify the speed. The operation of USM depends on friction at the interface between the moving rotor and stator, which is a key issue in the design of this interface for extended lifetime.
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Figure 1. Principle of Operation of a Rotary Traveling Wave Motor.
?3. PRINCIPLE OF OPERATION
The general principle of the operation of ultrasonic motors is to generate gross mechanical motion through the amplification and repetition of micro-deformations of active material. The active material induces an orbital motion of the stator at the rotor contact points and frictional interface between the rotor and stator rectifies the micro-motion to produce macro-motion of the stator. This mechanism is illustrated in shown in Figure 1. The active material, which is a piezoelectric material excites a traveling flexural wave within the stator that leads to elliptical motion of the surface particles. Teeth are used to enhance the speed that is associated with the propelling effect of these particles. The rectification of the micro-motion an interface is provided by pressing the rotor on top of the stator and the frictional force between the two causes the rotor to spin. This motion transfer operates as a gear leads to a much lower rotation speed than the wave frequency. ?
A stator substrate is assumed to have a thickness, tS, with a set of piezoelectric crystals that are bonded to the back surface of the stator in a given pattern of poling sequence and location. The thickness of the piezoelectric crystals is tp. The total height, h, is the sum of the thickness of the crystals and the stators (bonding layer is neglected). The overall height of the stator is also allowed to vary with radial position. The outer radius of the disk is b and the inner hole radius is a. To generate traveling wave, the piezoelectric crystals poling direction is structured such that quarter wavelength out-of-phase is formed. This poling pattern is also intended to eliminate extension in the stator and maximize bending. The teeth on the stator are arranged in a ring at the radial position.?
?4. THEORETICAL MODELING
The equation of motion of the ultrasonic motor can be derived from Hamilton’s principle. The analytical model has been derived by many authors (e.g. Hagood and A. McFarland [5], Kagawa et al [6]). The generalized equation of motion of the stator can be summarized as?
?where [M], [C], [K], [P], [G], are the mass, damping, stiffness, electromechanical coupling, and capacitance matrices, respectively. The vectors {x }, {j }, {FN} , {FT}, and {Q} are the model amplitude, the electric potential vectors the normal external force, the tangential external force and the charge vectors, respectively. The modal amplitude {x } and other generalized coordinates can be defined through energy methods such as Rayleigh Ritz method [5]. However, this method smears the contribution of the teeth and the variation of the stator ring as well as the support disk along the radial direction and may lead to undesirable results. Even though, 3-D finite element method (FEM) was reported [6] to be used to accurately predict the modal frequencies and transient response of the stator, it is computational intensive process. Further, the calculated response modes and associated frequencies that are determined by the 3-D FEM needs to be identified visually to find the designed mode. Due to the disadvantages for the methods mentioned above the modified annual finite element described in [7] is used and it is based on the symmetrical characteristics of the ultrasonic motors. The annular finite element is shown as in Fig. 2, where w1, w2 y 1, and y 2 are the degree of freedoms. The transverse displacement w across each element is assumed to be of the form given by the equation
, for R1 < R2
?where w nm is the radial resonance frequency and the index m, n are mode along the q and r direction, respectively. If we assume that the transverse shear and rotary inertial effects are negligible, the elemental mass, stiffness can be derived using the standard variational methods. Thus, the natural frequency and modal shape can be found by solving the eigenvalue problem.?
?Using consistent mass formulations, the effect of the stator teeth can also be included. Details of the formulation of other generalized coordinates are treated similar to those in [7] and will be presented by the authors’ in a future publication.??
5. ANALYSIS OF PIEZOELECTRIC MOTORS?
The analysis of the nonlinear, coupled rotor-stator dynamic model discussed above has demonstrated the potential to predicting motor steady state and transient performance as a function of critical design parameters such as interface normal force, tooth height, and stator radial cross section. A finite element algorithm was incorporated into the analysis and a MATLAB code was developed to determine the modal characteristics of the stator. The model accounts for the shape of the stator, the piezoelectric poling pattern, and the teeth parameters. Once the details of the stators are selected the modal response is determined and is presented on the computer monitor, as shown for example in Figure 2, where the mode (m, n) = (4, 0) is presented. An electronic speckle pattern interferometry was used to corroborate the predicted modal response and the agreement seems to be very good as can be seen in Figure 3 on the left. ?
Using MATLAB we developed an animation tool to view the operation of USMs on the computer display. The tool allows to show the rotation of the rotor while a flexural wave is traveling on the stator (Figure 4).?
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Figure 2: An annular finite element.
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?Figure 3: Modal response and resonance frequency (left) and experimental verification (right).
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?Figure 4: Animation tool for viewing the operation of USM. The stator is shown with traveling wave and the rotor is rotating above the stator.
Using this analytical model that employs finite element analysis, motors were constructed. The predicted resonance and measured resonance frequency for a 1.71-in diameter steel stator are represented in Table 1. The results that are presented in this table are showing an excellent agreement between the calculated and measured data. To examine the effect of vacuum and low temperatures, a 1.1 inch USM was also tested in a cryo-vac chamber that was constructed using a SATEC system and the torque speed was measured as shown in Figure 7. The motor that was servo-controlled showed a remarkable stable performance down to about -48oC and vacuum at the level of 2x10-2 Torr. This result is very encouraging and more work will be done in the future to determine the requirements for operation of USMs at Mars simulated conditions.
TABLE 1. The measured and calculated resonance frequencies of a USM’s stator.?
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Figure 7. Measured torque-speed curve for a 1.1-inch diameter USM at -48o C and 2x10-2 Torr.
6. CONCLUSIONS
A finite element model was developed to analyze the spectral response of ultrasonic motors with various geometrical configurations and construction materials. The modal response and the predicted resonance conditions were corroborated experimentally using spectral measurements and interferometric analysis. Further, user interface interactive tools were developed for a MATLAB platform simplifying the analysis of the modal behavior of USMs and allowing the study of their response to various stator parameters.
ACKNOWLEDGMENT
The authors would like to thank Nesbitt. W. Hagood IV, Aeronautics and Astronautics, MIT, for his assistance in this study under a TRIWG contract. The results reported in this manuscript were obtained under the Planetary Dexterous Manipulator Task, that is managed by Dr. Paul Schenker and it is a TRIWG task that is funded by a JPL, Caltech, contract with NASA Headquarters, Code S, Mr. David Lavery and Dr. Chuck Weisbin are the Managers of TRIWG.
REFERENCES?
1. M. Hollerbach, I. W. Hunter and J. Ballantyne, "A Comparative Analysis of Actuator Technologies for Robotics." In Robotics Review 2, MIT Press, Edited by Khatib, Craig and Lozano-Perez (1991).
2. A. M. Flynn, et al "Piezoelectric Micromotors for Microrobots" J. of MEMS, Vol. 1, No. 1, (1992), pp. 44-51.
3. E. Inaba, et al, "Piezoelectric Ultrasonic Motor," Proceedings of the IEEE Ultrasonics 1987 Symposium, pp. 747-756, (1987).
4. J. Wallashek, "Piezoelectric Motors," J. of Intelligent Materials Systems and Structures, Vol. 6, (Jan. 1995), pp. 71-83.
5. N. W. Hagood and A. McFarland, "Modeling of a Piezoelectric Rotary Ultrasonic Motor," IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol. 42, No. 2, 1995 pp. 210-224.
6. K. Kagawa, T. Tsuchiya and T. Kataoka, "Finite Element Simulation of Dynamic Responses of Piezoelectric Actuators,", J. of Sound and Vibrations, Vol. 89 (4), 1996, pp. 519-538.
7. D. G. Gorman, "Natural Frequencies of Transverse Vibration of Polar Orthotropic Variable Thickness Annular Plates, " J. of Sound and Vibrations
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