1121. Development of two modifications of piezoelectric high resolution rotary table

Transcription

1 1121. Dvlopmnt of two modifications of pizolctric high rsolution rotary tabl R. Bansvičius 1, A. Bubulis 2, I. Grybas 3, V. Jūrėnas 4, G. Kulvitis 5 1, 2, 3, 4 Kaunas Univrsity of Tchnology, Donlaičio 73, LT Kaunas, Lithuania 5 Vilnius Gdiminas Tchnical Univrsity, Saulėtkio al. 11, LT Vilnius, Lithuania 1 ramutis.bansvicius@ktu.lt, 2 algimantas.bubulis@ktu.lt, 3 ignas.grybas@stud.ktu.lt, 4 vytautas.jurnas@ktu.lt, 5 gnadijus_kulvitis@gama.vtu.lt (Rcivd 10 Octobr 2013; accptd 20 Novmbr 2013) Abstract. Th aim of this papr is to dscrib two modifications of high rsolution rotary tabls with angular position control, basd on th transformation of rsonant oscillations of pizolctric transducrs into continuous or start-stop motion. Exact angular position of th tabl is achivd by application of intgratd classical rotary position ncodrs and fdback systm, rlatd to th givn position or angular vlocity of th dvic. Dimnsions and cost of th tabl should b dramatically rducd, thus nsuring comptitivnss in modrn markts. Kywords: pizolctric motor, high rsolution, rotary tabl, photolctric ncodr. 1. Introduction Thr is a grat dal of rsarchrs who ar dvloping various pizolctric dvics, including rotary tabls and motors [8]. Howvr, only svral companis managd to produc and supply such objcts to th markt. Grman company PI (Physik Instrumnt GmbH & Co, Grmany) dvlopd pizotabl M 660, charactrizd by angular rsolution up to 4 µrad and maximal angular vlocity, qual to 2 rv/min [9]. Tchnical paramtrs of this product ar xcllnt, but pric rachs 1000 EUR and that limits th cass of its practical us. Nanomotion Ltd (Isral) commrcialisd its FBR060 modl, which utiliss th sam way of motion gnration, as that of prviously dscribd dvic [10] and th cost is narly th sam, although th main tchnical faturs ar diffrnt. Anothr opration principls basd on transformation of non-harmonic oscillations (stick-slip ffct) ar mbodid by companis Attocub Systms AG (Grmany) and PizoMotor AB (Swdn) in th modls ANR101/NUM Closd Loop [11] and Pizo LEGS WavPlat [12]. Th prics of both pizolctric tabls ar vn highr compard to th ons discussd bfor. In addition, pizomotors dsignd by company PCB Motor ApS (Dnmark) should b mntiond. Ths motors ar manufacturd on printd boards and hav no outr covrs (for xampl, PCBM 30-H25 [13]). Nonthlss, th lattr positioning stags ar of diffrnt prcision class. Information providd in this articl mainly dals with th dvlopmnt of two vrsions of th novl tabl, basd on th combination of standard photolctric rotary ncodrs (A36-F V and A58-F V), producd by Prcizika Mtrology (Lithuania), and plat-typ pizolctric actuators, invntd in Kaunas Univrsity of Tchnology (Lithuania). Both modifications act as prototyps for th industrial products that would b charactrizd by high quality and rlativly low cost. 2. Optimal topology of lctrods Whn dsigning a plat-typ pizolctric driv usd in this work, a grat attntion was paid to optimal topology of lctrods on pizocramic lmnt. This issu was takn into considration whn prforming R&D projct PizoAdapt [14]. During problm formulation for multi-dimnsional pizolctric transducrs in trms of optimal lctrods configuration, th following constrains ar takn into account: unification of xcitation voltag, gnration of rvrsal motion and achivmnt of maximum fficincy. Th first rquirmnt dals with voltag of th sam frquncy, constant amplitud and phas, supplid by powr sourc. Th scond on 2124 VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN

2 is mt by changing only polarity of th powr sourc, whil th third on is mt whn th surfac of pizolmnt is covrd by lctrods compltly and all thir zons ar simultanously xcitd using appropriat polarity voltag. This voltag, rfrring to th scond constraint, diffrs just by a phas, dpnding on th mod of oscillations dsird to b xcitd. Aftr dtaild rsarch it was found that in ordr to obtain maximum fficincy, th functioning of pizolctric plat should satisfy th following xprssion [14]: maxa f k = {y k } T {R }P k = y k R cos γ k P k, (1) whr A k f is ffcint work; y k is valu of vctor of pizolmnt s natural form; R is valu of vctor of quivalnt mchanical forc; γ k is angl btwn both vctors; P k is constant. For numrical dtrmination of optimal lctrods, th topology to b applid to th lctrods of pizotransducr has to b sctionnd by mans of finit lmnts (FE) so xcitation voltag s polarity in th cntr of unitary finit lmnt is tratd as optimisd paramtr. Th sign of polarity can b found comparing dirctions of quivalnt mchanical forc vctor and that of pizolmnt s natural form. Basd on that, th ssntial critrion of th ovrall problm is th angl btwn two givn vctors, which has to b minimizd. Th cofficint of fficincy is [14]: cos γ k = {y k } T {R } y k R. (2) Aftr calculating cos γ k for ach surfac lmnt of pizotransducr, th optimal topology of lctrods is dfind. Sign of cosin function mans th sign of xcitation voltag polarity. If cosin is positiv, quivalnt mchanical forc acts in ncssary dirction, othrwis (i.. cosin is ngativ) thr is a nd to chang voltag polarity. Th gratr valu of cosin is, th mor influnc corrsponding finit lmnt has on trying to induc crtain mod of vibrations in pizolctric lmnt [14]. If optimisation calculations ar associatd with dfind natural frquncy, th valu of vctor of pizolmnt s natural form is constant as wll. In such cas fficint work only dpnds on th valu of cofficint of fficincy, so optimal configuration of lctrods is dtrmind by minimising dscribd angl. Angl γ k can b changd, if only dirction of quivalnt mchanical forc vctor is changd. Such procdur is implmntd whn xcitation voltag polarity is modifid [14]. Optimal topology of two-dimnsional pizocramic lmnt lctrods was computd and statd as an xampl, according to th formulatd algorithm, with finit lmnt mthod and ANSYS softwar to b applid. Analyzd pizoplat was constraind in its cntral nods, sinc pizolctric drivs of this typ ar oftn applid for gnrating rotational motion. Rsult of such calculation (i.. cofficints of fficint action), attributd to th cntr of ach finit lmnt mass, is givn in Fig. 1a. Bright thick lin stands for sparatd lctrod zons having th sam xcitation voltag with phas shiftd by π. Fig. 1b rvals topology of lctrods so as to induc longitudinal-bnding mod oscillations in 2D pizocramic lmnt. It was cratd rfrring to prsonal nginring prcption and intuition. Obviously, configurations ar vry similar in both cass [14, 15]. Fig. 1. a) FEM-basd optimisation of lctrods topology: cosin valus (cofficints of fficincy) ( 0.1) for two-dimnsional pizocramic lmnt constraind in its cntral nods; b) topology of lctrods cratd rfrring to prsonal nginring prcption and intuition [4, 5] VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN

3 3. Rotory tabl modifications With th aim to dfin tchnical proprtis of potntial industrial pizolctric high rsolution tabl, two initial rlvant modifications wr constructd incorporating standard photolctric rotary ncodrs (A36-F V and A58-F V) and plat-typ pizolctric drivs, as it was prsntd in th introduction of this txt. Both tabl vrsions mploy multilayr pizocramic lmnts with sctiond lctrods, mad by Noliac Group (Dnmark), with dimnsions bing 20 mm 4.5 mm 2 mm (for ncodr A36) and 30 mm 7.5 mm 3 mm (for ncodr A58). Numbr of layrs was 40 for both plats. Positions of th tabls wr rgistrd using two and thr axis radout dvics CS Intgration of mntiond ncodrs and pizodrivs, which contact with intrnal cylindrical surfac of rotating part of th tabl, is shown blow (s Fig. 2, 3). c) Fig. 2. First modification of pizolctric high rsolution rotary tabl: photolctric angular position ncodr A36-F V with (a) and without (b) rotating part; optimisation schm for contact lmnt trajctoris (c): 1 rotating part, 2 prcis ring, 3 pizolctric multilayr plat, 4 contacting lmnts, 5 spring, 6 sctiond lctrods; rsonant frquncy 75.2 khz, harmonic xcitation amplitud 10 V Gnrally dynamic charactristics of th tabl ar significantly influncd by motion trajctoris of contacting lmnts. Taking into account this fact, a fw tchnical solutions wr proposd (Fig. 2c and Fig. 4a-b) to optimis th trajctoris dpnding on th maximal angular spd of th dvic. Longitudinal first mod and bnding scond mod (in th plan of pizoplat) vibrations ar inducd within pizolctric transducr in both tabl modifications; that lads to lliptical trajctoris (with mutual phas diffrnc of 180 o ) of ithr contacting points. Th shap of llips is dfind by both rsonant frquncy diffrnc, which is also govrnd by gomtry of pizolctric transducr, and opration rgim, which usually attains frquncy valu in btwn rsonant frquncis, attributd to ach oscillation mod. c) Fig. 3. Scond modification of pizolctric high rsolution rotary tabl: photolctric angular position ncodr A58-F V with (a) and without rotating part (b); angular position rgistration dvic CS 3000 (c); rsonant frquncy 42.1 khz, harmonic xcitation amplitud 10 V 2126 VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN

4 Th schm providd in Fig. 2c nabls to control motion trajctory of discussd contacting lmnts by mans of potntiomtr R in th rang from longitudinal vibrations of pizoplat with rspct to y axis (middl position of potntiomtr) to lliptical ons (top or bottom position of potntiomtr) in xy plan. Evn furthr limits for rgulation of trajctory ar st, if on applis th schm shown in Fig. 4a (i.. from longitudinal vibrations with rspct to y axis to transvrsal oscillations with rspct to x axis). Th sam ffct is obtaind whn using signal transformr with symmtrical output (Fig. 4b). 4. Exprimntal rsults Fig. 4. Schms for optimisation of motion trajctory of contacting lmnts Th schms rvald in Fig. 2c and Fig. 4a, b wr utilisd in xprimnts during invstigation of two vrsions of th novl pizolctric rotary tabl. Trajctoris of 2D vibrations of rfrnc point of pizolctric rotary tabl output link wr formd using laboratory xprimntal stup. Its structural schm is disclosd in Fig. 5, whil th major rsults ar dmonstratd in Fig. 6 and 7. In ordr to masur rfrnc point (AT) vibrations with rspct to X and Y dirctions, lasr vibromtr (LV) Polytc was mployd, consisting of lasr snsor OFV-130-3, intrfromtr OFV-512 and vibromtr controllr OFV Oscillations of pizolctric transducr ar gnratd whn harmonic signal is supplid from signal gnrator Agilnt 33220A (G) via signal amplifir EPA-104 (ST). Signals obtaind from lasr vibromtr ar passd to four-channl oscilloscop PicoScop-3424 (OSC) and procssd by appropriat softwar. Synchronisd gnrator signal is rquird, so that idntical duration tim signals associatd with positions X and Y, would b adoptd. In such cas vibromtr data is stord in oscilloscop and transfrrd to computr whn starting with th sam phas of gnrator in both X and Y positions. For graphic rprsntation of formd trajctory in th computr, th stord data is xtractd pair-by-pair (X and Y) and plottd in XY coordinat-basd graph. As a rsult narly llips-shap figur is got. Fig. 5. Structural schm of xprimntal stup for trajctoris of 2D vibrations of rfrnc point of pizolctric rotary tabl output link to b masurd: PZT pizolctric transducr, AT rfrnc point of pizotransducr s output link, X and Y masurmnt dirctions of rfrnc point vibrations, LV lasr vibromtr, OSC oscilloscop, PC computr, G signal gnrator, ST signal amplifir VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN

5 Fig. 6. Dynamic proprtis of pizolctric rotary tabl with photolctric ncodr A36: a) amplitud-frquncy charactristics of transducr s contacting point; b) motion trajctory (longitudinal vs transvrsal) of transducr s contacting point whn voltag (10 V) is supplid to on pair of lctric contacts (vibrational frquncy 75.1 khz) Fig. 7. Dynamic proprtis of pizolctric rotary tabl with photolctric ncodr A58: a) amplitud-frquncy charactristics of transducr s contacting point; b) motion trajctory (longitudinal vs transvrsal) of transducr s contacting point whn voltag (14 V) is supplid to on pair of lctric contacts (vibrational frquncy 42.1 khz) Fig. 8. Exprimntal rsarch of angular rsolution of th pizolctric rotary tabl: a) minimal angular displacmnt (0.31 ) of pizolctric rotary tabl with photolctric ncodr A36 (R = 22 mm) whn numbr of triggr cycls is qual to 50, amplitud 10 V; b) minimal angular displacmnt (1.7 ) of pizolctric rotary tabl with photolctric ncodr A58 (R = 27 mm) whn numbr of triggr cycls is qual to 50, amplitud 16 V 5. Conclusions Two modifications of pizolctric high rsolution rotary tabl, that act as prototyps for potntial industry-dvotd products, wr dsignd, constructd and prsntd in this work. Succssful intgration of standard photolctric rotary ncodrs (A36-F V and 2128 VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN

6 A58-F V) and plat-typ pizolctric drivs rsult in promising applications. Optimal topology of lctrods with rspct to 2D pizoclctric lmnt was dtrmind by mans of finit lmnt mthod. Thr tchnical solutions (on schmatics lvl) wr originally proposd to optimis motion trajctoris of contacting lmnts, which play a crucial rol btwn pizoplat and rotating part of tabl. According to th xprimntal rsults, th tabl with photolctric ncodr A36 is abl to gnrat a slightly mor uniform rotational motion and achiv highr rsolution (minimal displacmnt 0.31 ), than tabl with ncodr A58 (minimal displacmnt 1.7 ). Howvr, prformanc of both tabl vrsions can b tratd as mting th initial rquirmnts. Acknowldgmnt This rsarch is fundd by Rsarch Council of Lithuania (Projct PizoTabl, No. MIP 094/12). Rfrncs [1] Li J., t al. A pizolctric-drivn rotary actuator by mans of inchworm motion. Snsors and Actuators A: Physical, Vol. 194, 2013, p [2] Buchi R., t al. Inrtial drivs for micro- and nano-robots: two novl mchanisms. SPIE Procdings, Vol. 2593, 1995, p [3] Wang C. Y., Chang H. S. Dsign and prformanc of a pizolctric actuatd prcis rotary positionr. Rviw of Scintific Instrumnts, Vol. 77, 2006, p [4] Shim Y. J., Gwon G. D. Pizo-drivn mtrological multiaxis nanopositionr. Rviw of Scintific Instrumnts, Vol. 72, Issu 11, 2001, p [5] Zhang H., t al. Impact driv rotary prcision actuator with pizolctric bimorphs. Frontirs of Mchanical Enginring in China, Vol. 3, Issu 1, 2008, p [6] Gao W., Sato S., Arai Y. A linar-rotary stag for prcision positioning. Prcision Enginring, Vol. 34, 2010, p [7] Watson B., Frind J., Yo L. Pizolctric ultrasonic micro/milli-scal actuators. Snsors and Actuators A: Physical, Vol. 152, 2009, p [8] Uchino K. Pizolctric ultrasonic motors: ovrviw. Smart Matrials and Structurs, Vol. 7, 1998, p [9] Catalogu of Company PI, 2013, [10] FBR sris rotary stag. Nanomotion, [11] Attocub Pionrs of Prcision. Product Catalog, 2012 and 2013, Miunich. [12] Pizo LEGS WavPlat. Pizomotor, [13] Catalogu of Company PCBMotor. 2013, [14] Rsarch and dvlopmnt of th multi-dgr-of-frdom mchatronic displacmnt gnration/masurmnt systms with nanomtr rsolution (acronym PizoAdapt). Rport for Hightch dvlopmnt program, [15] Cpulkauskas A., Kulvitin R., Kulvitis G. Computr algbra for th formation structural matrics of pizocramic finit lmnts. Lctur nots in computr scinc, Springr-Vrlag, Brlin, Hidlbrg, Nw York, Vol. 3992, 2006, p VIBROENGINEERING. JOURNAL OF VIBROENGINEERING. DECEMBER VOLUME 15, ISSUE 4. ISSN