]

卸絲氏4

1 (課程博士(英文))Date of submission (month day, year)

Department ofS加denHDNumber

Mechanical Engineering
Pplicant's nameJuly 3^d,2023

D 209106
Supervisors

Prof. Kotaro Takayama

Mohamed MostafaAbdelaziem Kha1Ⅱ

Abst,act (Doctor)
Title ofThesis

Design and contr010fa Micro ultrasonic Motor・Based lnsect・scale Robot for lnspection
Purposes

Approx.80o words
The inspection and monitoring of industrial sites, machines, and infrastructure are impor[ant issues for their
Sustainabiliw and further maintenance. A major problem that always exists in civil structures and industrial
Sites is that they are rarely uniform in shape and are not typica11y designed with considerations for easyinspection access. The same problem is associated 、¥ith machines,、Nhere inspection ofcomplicated machines
Iike turbine en今inesrequiresthe disassembly ofa lot ofcomponents、Nhich can be costly and time・consuming.
A common elementthat exists in a11industrial sites, civil structures, and machines is the countless number of加bes and PゆeHnesto transport aⅡ kinds ofauidic materials. we considerthese tubes and Pゆelines as directroutes to the core ofan inspection site or a complicated machine.＼Ne cunendy take advantage ofthese pipes
and tubes to explore inaccessible structures and the core of compHcated machines by the borescopes.
Although it provides crucialinformation,itis extrinsica11y manuaⅡy actuated by an operator which makes it
hard to point it to a specific spot.1t is time to think then ofthe next generation ofborescope as a miniature
robot intrinsica11y actuated and capable of navigating inside nano、N tubes and Pゆelines efficiently. This
research addresses different chaⅡenges of scalino down robots, that require the signi6Cant integration ofComponenttechn010gies such as actuators, fabrication techniques, and sensing machines.
The first cha11enge is the driving mechanism, downsizing an actuator to a micro size comes with a lot ofProblems. For example, electromagnetic actuators that dominate atthe macro・scale dhninish their po、Ner at
the micro・scale due to their scaling law.1nstead, piezoelectric ultrasonic motors perform at such a scale as themostprominent microactuatorbecause oftheirhigh・power densiw and good macl)inability. However, despite
their great scalabiHty, they have obvious nonlinear and time・varying characteristics that deteriorate theirPerformance in pr010nged operations.圦,1e investigated that problem by studyino the effectiveness ofthe
motor's intemal parameter changes, such as atemperature rise and the resonant 6'equency variation. Forthat,a mathematical model was derived from scratch, f0110wed by several experiments to verify the hypothesis
experimenta11y. The experiments also prove thatsuch deviation affected the motor performance by enlarging
its steady・state enor with time. To solve this dilemma, we introduced a model・free, real・thne・adaptive
extremum seeking contr011er (ESC)that can coop 、vith the non・1inear characteristics ofthe motor、 To build
the control structure, we constructed the smaⅡest rotary actuator‑sensor system in the 、Norld that consists ofa

micro・ultrasonic motor, a tiny TMR sensor, and a tiny magnet. The resulting system was assembled into a
Size 、Nith a height of 3.2 mm, a 、vidth of 3.2 mm, and a len旦th of 5 mm. several experiments that involve
Constant and variable speed commands sho、N thatthe contr011er succeeded to drive the motor atthe desired
angular velociw with a minimum steady・state error by continuously tracking and localizing the optimum
driving 介'equency、The second cha11enoe is the design itself ofthe robot. An inspection robot is expected to reach inaccessible
areas by navigation in confined places including inside narro、N tubes and pipelines in harsh 、V01'kingenviromnents. To fulaⅡ these requirements, we havetaken design principles adapted from the caterpi11ar. The
Caterpi11ar's prowess is due to a combination ofdesign featuresthat worktogetherto pennitrapid and smooth
10comotion. This functionaliり,, is achieved by the proposed robot by a light rigid stNcture made of 21inks
Connected by an activepivotjointthat a110、刃Sthe climbing robotto extend and aex. The pivotjoint alablesthe
robot to navigate inside a wide range ofPゆelineS 6'om 12 t025 mm by changing its height. The joint also
a110ws the robotto exert a force againstthe upper 、ua11S for holding the robotinside the Pゆes, which can betreated as an integrated holdinσ force mechanism. T、V0 10comotion modes to propelinside pipeHnes arePresented, and a proposed motion strategy to navigate complex pipe configurations, including vertical andbent Pゆes,is presented and validated by a series ofexperiments.
To extend the working domain ofthe inspection robot, we study the possibiliw ofmerging the robot with anadhesion mechanism to perf0如 more cha11enging tasks such as replacing manualinspection at heights. For
that, numerous adhesion methods were investigated until we come up with an approach ofusing lo、N・cost dry
adhesive materials to address climbing cha11enges, including surface・to・surface transitions, and vertical andinverted locomotion with high payload capacity. This idea was inspired by the climbing action ofcatelpi11ars

On vertical surfaces as stationaly legs provide anchoring force to hold their 、Neight.1n addition, different dry
adhesive materials were analyzed and the selection criteria for the appropriate adhesive materialto cover tl〕efUⅡ range ofmotion were also demonstrated. Final experiments provethe viability ofthe insect・scale robotto

navigate complex structures (verticaⅡy and invertedly) while performing different cases ofsurface・to・surface
transitions. A payload・mass ratio of 120% was also achieved 、Nhile climbing on a vertical surface.
The findings ofthis thesis prove the functionaliw ofthe insect・scale robot for various maintenance tasks, andit also demonstrates the potential ofl0訊1・cost dry adhesive materials in the 6eld ofmhliature climbing robots.
Usinσ the concept ofmimicking the locomotion pattem ofbi010gical m'eatures results in an unprecedented
mobiliw performance for an insect・scale robot.