Development of deep-sea drone by spherical ultrasonic motor

Transcription

1 Development of deep-se drone y sphericl ultrsonic motor S. Toym 1, U. Nishiw 2, O. Mtsur 3 1, 2 Tokyo Noko University of Technology, Kognei, Tokyo, Jpn 3 QI Inc., Fukuur, Knw, Yokohm, Jpn 1 Corresponding uthor E-mil: 1 toym@cc.tut.c.jp, 2 n-uichi@cc.tut.c.jp, 3 mtsur@qi-inc.com Received 15 August 218; ccepted 27 August 218 DOI Copyright 218 S. Toym, et l. This is n open ccess rticle distriuted under the Cretive Commons Attriution License, which permits unrestricted use, distriution, nd reproduction in ny medium, provided the originl work is properly cited. Astrct. The world ocen occupies 7 % on the erth nd the verge se depth is out 4, m. More thn 8 percent of it hs not een investigted precisely nd the ottom shpe of the se hs not een mpped. When doing resource-serching in the future, the precise mps must e required. So, the uthors hve developed drone movle round 4, m deep se to mesure the ottom of the ocen. It is sed on spheres, which includes cmers, tteries, some sensors nd controllers. It cn rotte sphericl rotor sensing widely to otin the informtion out the ottom of the se. At the first step of the reserch, the uthors hve mde sic eperiments of the motor s performnce in wter. The uthors hve otined the ecellent results in mneuverility, temperture durility, nd shock resistnce of the motor. Keywords: ultrsonic motor, wterproof, drone. 1. Introduction The purpose of this reserch is to mke mp of the ottom of the se ll over the world. At the present, only 15 percent of it hs een mesured nd mpped. However, it is only shllow se round the continents or islnds nd the rest is unknown. In the deep se, there my e four times s much s rre metl, hydrotherml deposits nd mngnese nodule compring to the lnd. In the future, the precise mps will e necessry when mining them. Generlly speking, in order to mke se mps, the reserch ships hve used ultrsonic technology to survey the se ottom y detecting reflecting wves, ut its ccurcy is poor, nd it cnnot e used for resource serching. To mke the precise mps, it requires deep-se sumrines movle round 4, m deep se. However, they re very epensive, nd they cn mesure very nrrow re t once. To cover ll deep se, inepensive sumrines re necessry. Since severl hundred tmospheric pressure is pplied in the deep se, the resistnce shpe is only sphere to support the pressure in disperse. So, ll moilities in the deep se should e sed on sphere in design. So, the uthors hve proposed the deep-se drone y sphericl ultrsonic motors. It hs dvntges s follows: 1) It hs only sphericl rotor nd three ring type sttors. Simple structure nd esy mintennce. Low cost. Esy use of group roots (severl hundreds of drones re ville t resonle cost). 2) Rottionl sphericl rotor with sensors covers wide re. 2. Concept of deep-se drone 2.1. Sphericl ultrsonic motor An ultrsonic motor is kind of friction motor. If frictionl force hs een kept in wter, it will work well. Adding tht, its structure is very simple. It consists of ring type elstic ody with pieoelectric cermics (sttor) nd rotor [1-4]. A sphericl ultrsonic motor is n ppliction y three sttors nd sphericl rotor (Fig. 1) [5, 6]. The control is esy y phse differences of pplied voltges to ech pieoelectric cermics. It hs dvntges; three rottionl degrees of freedom, ISSN PRINT , ISSN ONLINE , KAUNAS, LITHUANIA 97

2 DEVELOPMENT OF DEEP-SEA DRONE BY SPHERICAL ULTRASONIC MOTOR. simple structure, no reduction gers (high torque nd low speed chrcteristics), short response time, no rking mechnism t rest, nd little ffected y mgnetic or current field Concept of deep-se drone with sphericl ultrsonic motors The imge of deep-se drone is shown in Fig. 2. It hs four sphericl ultrsonic motors. The two motors t the top of the drone re rotting with cmers, tteries nd computers. The middle motor is t rest nd hs some tteries for driving other motors, GPS, ccelerometers, computers nd n iridium moile phone. The lst motor is promoting the drone y rotting propeller. It cn lso control the direction of the propeller. All motors sttors re connected to the middle sphere s ttery y the cles specilly mde for deep se. All motors cn communicte y Wi-Fi (the distnce to ech motor is just out 1 cm). Fig. 1. Overview of sphericl ultrsonic motor Fig. 2. Deep-se drone 3. Driving in wter The uthors hve reserched ultrsonic motor driving in wter previously [6]. In the reserch, using TR motor (motor with two degree of freedom of Trnsltionl nd Rottionl movement in one joint), the uthors hve succeeded in driving it in wter. It should hve selnt mterils on electrodes nd keep firm contct of the sttor nd the rotor in wter; tht is to sy, it is necessry to eliminte the wter film etween them to trnsmit force from the sttor to the rotor y contct. The uthors hve pplied knurled rotor to prevent the thin wter film nd psted silicone ruer to the electrodes to otin good rottionl nd trnsltionl movement in wter. Bsed on the previous reserch, the uthors hve spryed poly vinyl resin to electrodes, the sphericl rotor (plstic ll) nd the sttor. It is ecuse it mkes very thin film nd no disturnce to rotte sphericl rotor. First, the uthors hve mesured impednce out one pir of the rotor nd the sttor. The results re shown in Fig. 3. It shows tht it hs the cler resonnt frequencies in wter. It shows possiility of moving in wter. Compring to the cse of driving in the ir, the resonnt frequency shifts to the lower side y 3 or 4 kh due to dditionl wter mss effect, tht is, the virtion of the sttor moves with the surrounding wter. Net, the uthors hve investigted the rotor mterils. Since the rotor mteril requires dequte elsticity nd mss, the uthors hve compred some kinds of resins. The eperiment results show tht the resonnt nd nti-resonnt frequencies of the sttor re not cler, ut oserved. This is ecuse resin spheres re reltively light nd ffected y floting force in wter, nd the contct force etween the sttor nd the rotor is decresing. Bsed on these eperiment results, the uthors hve mde eperiments of rotting the sphericl ultrsonic motor in wter successfully with selnt coted sttors nd resin spheres. It shows good mneuverility in wter. In the eperiments so fr, the higher voltge should e pplied to mplify the virtion (the mplitude of virtion of the sttor is depressed in wter) nd dequte wterproof should e 98 VIBROENGINEERING PROCEDIA. SEPTEMBER 218, VOLUME 19

3 treted in order to work in wter. Impednce [Ω] Impednce [Ω] DEVELOPMENT OF DEEP-SEA DRONE BY SPHERICAL ULTRASONIC MOTOR. ) Selnt sttor, selnt rotor in the ir ) Selnt sttor, selnt rotor in wter Impednce [Ω] ) ) ) Selnt sttor, no selnt rotor in the ir ) Selnt sttor, no selnt rotor in wter Impednce [Ω] c) d) Fig. 3. Impednce of sttors with nd without selnt ) No selnt sttor, selnt rotor in the ir ) No selnt sttor, selnt rotor in wter ) No selnt in the ir ) No Selnt in wter Applied voltge Resonnt frequency Phse difference Rottionl speed 37 Vp-p 45.5 kh 9 3 rpm ) ) Fig. 4. Sphericl ultrsonic motor in wter 4. Durility out the temperture of environment There re some plces where the se temperture reches to 2 or 3 such s hydrotherml deposits nd se volcnoes. Therefore, the sphericl ultrsonic motor hs to e durle for the high temperture environment. The pieoelectric element nd the glue re likely to get dmge y high temperture. So, the uthors hve emined closely the pieoelectric element mterils durle for high temperture, tht is, the Curie point should e more thn 3. Besides tht, the uthors hve reserched it out the electromechnicl coupling coefficient to show the rte of efficiency from electricl input to the mechnicl energy, the mechnicl qulity coefficient to show smll loss of elstic deformtion nd the pieoelectric constnt to show the rte of the distortion of the pieoelectric element y n electric field. The uthors hve chosen the pieoelectric element #N6 of Tokin Co. It hs high Curie point 325 nd ecellent chrcteristics of electromechnicl coupling coefficient, mechnicl qulity nd elstic deformtion loss. The uthors hve lso investigted the high temperture durle glue. However most of the commercilly ville glues hve low glss trnsition point. So, s moderted even little ISSN PRINT , ISSN ONLINE , KAUNAS, LITHUANIA 99

4 DEVELOPMENT OF DEEP-SEA DRONE BY SPHERICAL ULTRASONIC MOTOR. mteril, the uthors hve chosen one-component epoy dhesive #TB2285 of ThreeBond Co. to show the 125 glss trnsition point, non-conductivity, the high detched onding strength, good dhesive strength nd ecellent hrdness. The uthors hve evluted this pieoelectric cermics nd the glue. The results re shown in Fig. 5. It shows tht the motor keeps movle due to mintining pieoelectricity within 12. The eperiments hve shown tht it is working for 9 min 3 sec in 12 environments. When driving it in higher temperture environment, working time my e shorter. However, short working time my e sufficient since the temperture of the motor does not go up suddenly round hydrotherml deposits. It my e sufficient time for tking photos nd mesuring the se ottom shpe Impednce [kω] Fig. 5. Impednce temperture chrcteristics Sphericl rotor is 1st nturl virtion mode Sttor y Holder is 1st nturl virtion mode Finite element method Nturl virtion nlysis NX Nstrn ver.9. Numer of elements: 14,871 Numer of nodes: 163,4 : 1st nturl frequency: H y: 1st nturl frequency: H : 1st nturl frequency: H Fig. 6. Virtion nlysis y FEM Hlf sine shock is direction Time [ms] M ccelertion [G] Time [ms] M ccelertion [G] 3 3 Time [ms] M ccelertion [G] 4 4 is direction Fig. 7. Impct eperiments 1 VIBROENGINEERING PROCEDIA. SEPTEMBER 218, VOLUME 19

5 DEVELOPMENT OF DEEP-SEA DRONE BY SPHERICAL ULTRASONIC MOTOR. 5. Durility out the virtion nd impct The sphericl ultrsonic motor gets dmge, or the rotor jumps out from the holder due to the virtion or impct when conveying it or throwing it to the se. To evlute it, the uthors hve modeled it y finite element method (NX Nstrn). The results re shown in Fig. 6. The first nturl frequencies re more thn 1 H to imply no need of creful opertion ordinrily. However, when it gets serious impct in cse of collision of the drones with ech other or impct with ottom, it my ecome serious prolems. So, the uthors hve mde eperiments out impct s follows. 1) Applied hlf sin curve with m ccelertion 2 G, 5 msec (hlf cycle time) long is nd is. 2) Applied hlf sin curve with m ccelertion 3 G, msec (hlf cycle time) long is nd is. 3) Applied hlf sin curve with m ccelertion 4 G, msec (hlf cycle time) long is nd is. In the cses of 1) nd 2), the motor hs firmly kept the rotor inside, ut in the cse of 3), the rotor hs jumped out. The rotor hd some dimples. But it shows norml rottion fter impct, nd the screws nd the holder hve no dmges. The stopper is necessry to prevent it (Fig. 8). In the se, the impct my not e serious due to dmping effect y the fluid, ut the stopper is indispensle in cse of serious ccidents. Stopper 6. Conclusions Fig. 8. Sphericl motor with stoppers The uthors hve otined conclusions s follows. 1) The sphericl ultrsonic motor shows good mneuverility in wter. 2) The sphericl ultrsonic motor is durle for 12 environments. 3) The sphericl ultrsonic motor hs the stopper to prevent the rotor s jumping out from the holder. It is durle for the virtion nd impct when ordinry deling. The uthors hve shown the possiility of deep-se drone y sphericl ultrsonic motor successfully. Acknowledgement Funding from Leve Nest Co., Ltd. is grtefully cknowledged. References [1] Ferreir P. A. M. High-performnce lod-dptive speed control for ultrsonic motors. Control Engineering Prctice, Vol. 6, Issue 1, 1998, p ISSN PRINT , ISSN ONLINE , KAUNAS, LITHUANIA

6 DEVELOPMENT OF DEEP-SEA DRONE BY SPHERICAL ULTRASONIC MOTOR. [2] Hoshin M., Mshimo T., Fuky N., Mtsur O., Toym S. Sphericl ultrsonic motor drive system for pipe inspection. Advnced Rootics, Vol. 27, Issue 3, 213, p [3] Mshimo T., Toym S. Virtion nlysis of cuic rotry-liner pieoelectric ctutor. IEEE Trnsctions on Ultrsonics, Ferroelectrics, nd Frequency Control, Vol. 58, 2, p [4] Nishiw U., Oohshi T., Toym S. Evlution of sphericl ultrsonic motor for spce in low temperture condition. Journl of Viroengineering, Vol. 19, Issue 7, 217, p [5] Nishiw U., Oohshi T., Toym S. Evlution of resistnce ginst virtion nd shock resistnce on sphericl ultrsonic motor. Journl of Modeling nd Optimition, Vol. 8, Issue 2, 218, p [6] Toym S., Nishiw U. Wterproof ultrsonic motor. Viroengineering Procedi, Vol., 217, p VIBROENGINEERING PROCEDIA. SEPTEMBER 218, VOLUME 19