CE & TECHNOLOGY No 88 - 2012 A NOVEL BI-DIRECTIONAL MICRO ROTATIONAL MOTOR DRIVEN BV V-SHAPED ELECTROTHERMAL ACTUATORS MO TO QUAY HAI CHi^U DAN D O N G B A N G C A C B O KICH HOAT NHl$T DANG CHO" V Dang Bao Lam, Dinh Khac Toan, Nguyen Tuan Khoa, Pham Hong Phuc, Vu Ngoc Hung Hanoi University of Science and Technology Received November 17, 2011; accepted January 17, 2012 ABSTRACT tn this paper the authors report a novel design of a bi-directional micnj rotational motor (MRM driven by four V-shaped electrothermal actuators Rotation of an outer rotor ring is achieved b conversion of reciprocating movement of the V-shaped actuators, which are arranged In the coupl that they are capable of generating a driving moment while working By using two couples of the driving actuators and the other two braking actuators, the motor can rotate bi-directionally, Theoret calculation of displacements and forces shows that the motor can produce a relatively large displacement with low driving voltage Simulation in Ansys has also been carried out, and the simulated results matched well with the calculated ones Acquired results point out that the pmpos model is ready hr the next steps - fabrication and test of the micm rotational motor T6M TAT Trong bai bdo ndy cdc tdc gii di xuit phuxyng dn thiit ki micro md ta quay hai chiiu duac din dqng bdng bdn bg kich ho^t nhigt ddng chu- V Bing cdch bd tri thich hgp theo timg cdp, cAc bd kich hoat lam viec tao cdc c$p ngdu lgc de din ddng vdnh rd to ben ngodi Nh& ca cau phanh hSm, thgc chit Id hai bg kich ho^t nhidt khdc mo ta duxrc thiet ki cd kha ndng ddi chiiu quay Cac bai todn ciiuyen vi va luc cho thiy micro md ta co thi t^o chuyen vi tuong ddi l&n v&i di$n dp din thip Kit qua thu dugc mo phdng bdng Ansys hoan todn phu hgp v&l cdc kit qua tinh todn Cdc kit qua thu duac cho thay micm mo ta duac thiet kd co thi ho^t dgng tdt, du diiu kidn de tiip tue che tao, dac va thO nghiem I INTRODUCTION „, , -J , r iL:tr-»*(With rapid development of MEMS market, besides already booming section or ,.„-.', •' * , MEMS devices of sensors, actuators are being more and more studied and applied into human life The most common ways of actuation are electrostatic, electrothermal, piezoelectric and magnetoslatic Among them, electrostatic and magnetostatic ones need a large applied voltage in order to achieve a large force and displacement On the other hand, electrothermal actuators can produce large force and displacement with low voltage [1] Until now, there is a number of articles reporting research results on electrothermal actuators In [2]-[4], thermal actuators with hot arm - cold arms have been used to produce a , , , , , ,, displacement while applying a driving voltage The advantage of this kind of thermal actuator is ability to gain relatively large force and displacement, but there are also some disadvantages as low structure rigidity and nonlinear relation between the driving i and displacement The thermal actuators using v-shaped beams [5H7] help to overcome those ,, problems For generating rotational movemenL Kim et al used inchworm motion [8], in which the rotor is wrapped by Iwo opposing belts which are connected to piezoelectric actuators In the inchworm motor designed by Sammoura [9], four gap-closing actuators are used to rotate a rotor Garcia and Sniegowski [10],[11] arranged electrostatic comb actuators so that linear motionthrough from actuators be transmitted J rotor linkage can mechanisms Mostto of those motors have their actuators placed outside of the rotor, thus this configuration can cause difficulties with transmission rotary movement "",.'7"!l""*u " ™ " / T out from the motors, The rotational motor proposed by the authors [12], in which four electrostatic comb actuators and ratchet mechanisms are used to rotate an outer ring, is designed to overcome JOURNAL OF SCIENCE & TECHNOLOGY No 88 - 2012 this shortcoming Using electro-thermal effect for actuation, Peng Yang et al [13) design a ring thermal actuator, in which the rotor ring is driven by twelve spokes with changeable length However, those types of rotational motors can only generate uni-directional movement beam which one end is connected to the Vshapcd beams, and Ihe other end is connected to the shoe Q) When a periodic voltage is applied between Iwo ends ofthe V-shaped beams, each wing of Ihe beam will expand and shrunk,^^ respectively, and makes the movable part ® move back and forth In this paper, Ihe author report a design of a new bi-directional rotational micro motor driven by four V-shaped electrothermal actuators Thanks to the arrangement of the acluators and two brake mechanisms, the motor is capable of moving bi-directionally An Important component ofthe motor is ihe anti-reverse mechanisms and ®, of which the role is to prevent Ihe rotor ring ID from going backward The anti-reverse mechanisms, in facL are also V-shaped actuators, which act as a brake mechanism CONFIGURATION PRINCIPLE When a periodic vollage is applied to the V-shaped actuators, the movable part O of the actuator will move forward and back For generating clockwise motion, acluators through their shoes (S) and create a couple of forces When voltage decreases (o zero, the beams retum to Ihc initial position At the same time, the antireverse mechanisms and ® are activated, the generated braking forces prevent the rotor ring from moving back The reversal rotation can be achieved by actuating ihe remaining actuators, i.e actuator Q> and ® AM) WORKING Figure shows Ihe configuration of an electro-thermal rotational motor, which consists of four V-shaped electro-thermal actuators ®-®, two anti-reverse mechanisms ®, © and an outer rotor ring ® The motion or mechanical power can be transmitted from Ihe actuators to the ring by friction between ring surface and the actuator shoes ® The actuator here refers to the V-shaped electro-thermal actuator with the width of each beam is6|im the gap between two beams is 4|im The movable part ® of the actuator is a Fig.l Coiifi^uralnm nf an eleclro-thcrmal rolalionul molur JOURNAL OF SCIENCE & TECHNOLOGY