別紙41 (課程博士(英文))Date of submission (month day, year)

TomoakiMashimo

DepaHment
StudentlD Number

MechanicalEn倉ineering
Pplica川's nameFebrual'y 19 2020

D111816
Supel'visors

Zhon牙 Zhang

Ayato Kenada

Abst"ad (Doct0釣Title ofThesis

Flexible Llnear Motors for Mobile continuum Robots

Approx.80o words

Organisms that exploit soft structures produce the incredible capabilities for10comotion and manipulation in complex natural envlronments. while
Conventional robots w'ith discrete links and ri牙id actuators are fast, strong, andeasy to contr01, they struggle to operate in such surroundings. S0丘 robots with adeformable, continuum body and soft actuators can potentia11y approach thisProblem due to their elasticity, safety of interaction, and environmental
adaptability. However, S0丘 actuators have several problems includin牙 a limited
Stroke, difficulty of contr01, and slow response time, restrictin牙 their deployment
On the other hand, ri今id actuators such as electroma今netic and piezoelectricmotors widely adopted today solve these drawbacks, but do not have the s0丘ness.
A combination of soft and classicaltechn010gies may address this chaⅡenge. This
thesis introduces a concept of aexible linear motors that consists of a ri号id lnotor'S
Stator and a aexible elon今ated shaft. By movin今 the aexible shaft linearly via
Chan曾es of a relative position to the stator, aexible linear motors provide a lar今eStroke, fast response time, and ease of contr01. This research shows two examples
Of how aexible linear motors can be realized and investi今ates how the above
advantages contribute to the mobility of continuum s0丘 robots
One is a nexible ultrasonic motor that consists of a sin曾le metalcube stator with ahole and an elastic and long coil spring inserted into the hole. when volta号es areapplied to piezoeleC仇'ic elements on the stator, a shaft inserted the hole moves
back and forth. To investi牙ate the influence ofsoftness on the ultrasonic motor, W'e
first inserted a slightly aexible coil spring and a solid sha丘 into the stator.＼入le
Change both sha丘S diameter w'ith micron、order accuracy to provide a pre、PI'essurebetween the stator and shaft to improve the output of the ultrasonic motor
Experiments show that the coil sprin牙 is easier to adjust the pre、pressure andProvides a lar牙er output. Next, we use the elastic and lon套 Coil sprin号 to brln曾丑exibility for the motor and enables a lar今e stroke. The coilsprin今 also works as aPosition sensor by regardin曾 itself as a variable resistance.1n order to clarify thedesign method010gy, the pre'pressure, motion model, and position sensin今 of theCoil spring are formulated. The resulting sensor、actuator system haS 牙ood
response characteristics, high linear北y, and robustness, without Teducin今aexibility and con訂,011ability.＼入re build a continuum robot based on two aexible
Ultrasonic motors and demonstrate feedback contr010fplanar motion based on theConstant curvature model.

The other is a aexible rack Plnlon actuator that consists of a Plnlon 今ear rotatedby Dc motor and a nexible meta11ic tube that works as a rack. Rotating the pinion
gear moves the aexible tube linearly by a enga今e with the helical groove on thetube surface. X入7e build a continuum robot whose section has three aexible rack

Pinion actuators connected in paraⅡel. The elon今ation and bendin牙 motion of each
Section can be contr011ed during operation by varying the speed of each aexible
tube. This design not only a110ws the expansion of the robot to otherwise
Unreachable work areas but also improves the locomotion velocity by 曾eneratin曾 aIar牙e traveling distance ofthe aexible tubes. First, we test two types oflocomotion

On the 牙round usin今 a continuum robot with the two sections (6 DOF). The results
Show that earthworm・1ike locomotion W北h a lar今e body stretch haS 今ood mobility
even in a slippery environment. Next, study how s0丘 and lar牙e deformations canenhance the climbin今 Capabilities of LEecH; a natura1 1and leech'inspired

Continuum robot with the one section (3 DOF) and two suction cups at the ends.
The lar今e deformations occurring in LEecH extend its workspace compared torobots based on constant curvature models, and we show successfU110comotion

transition from one surface to another at an曾les between o゜ and 180゜ inexperlment

The findin牙S in this thesis demonstrate that the proposed motors provide
Capabilities and behaviors that cannot be achieved by eitheT soft actuators orConventional rigid motors alone. using the concept of the aexible linear motor
results in continuum robots W北h good mobi1北y, and has the potentialto erase theboundary between conventionalri今id and soft robots.