• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.612-614
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• 1997

Silicon based micro mirror array is a highly efficient component for use in optical applications such as adaptive optical systems and optical correlators. A micro mirror array designed, fabricated and tested here is consisted of $5{\times}5$ single layer polysilicon, electrostatically driven actuators. In this paper, deflection characteristics and pull-in behavior of the actuators for analog control was studied and particularly, the influence of the residual stress in flexure beams for the restorative force of actuators was considered. The springs are modeled as a residual stress-free spring and a spring with residual stress. In calculation, a mirror with the residual stress-free springs has 30.3N/m spring constant and 31.1V pull-in voltage. On the other hand, a mirror with the stressed springs has 23.6N/m and 27.4V respectively. The experimental result, which is 20.5N/m and 25.5V, shows that the stressed springs ore well modeled.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.246-250
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• 2003

In this study, two new types of micro-grippers in which micro-fingers are actuated by piezoelectric multi-layer benders and stacks are introduced for the manipulation of micrometer-sized objects. First, we constructed a 3-chopstick-mechanism tungsten gripper, which is composed of three chopsticks: two are designed to grip micro-objects, and tile third is used to help grasp and release the objects through overcoming especially electrostatic force among some surface effects including electrostatic, van der Waals forces and surface tension. Second, a 2-chopstick-mechanism silicon micro-gripper that uses an integrated force sensor to control the gripping force was developed. The micro-gripper is composed of a piezoelectric multilayer bender for actuating the gripper fingers, silicon fingertips fabricated by use of silicon-based micromachining, and supplementary supports. The micro-gripper is referred to as a hybrid-type micro-gripper because it is composed of two main components; micro-fingertips fabricated using micromachining technology to integrate a very sensitive force sensor for measuring the gripping force, and piezoelectric gripper finger actuators that are capable of large gripping forces and moving strokes. The gripping force signal was found to have a sensitivity of 667 N/V. To the design of each of components of both of the grippers. a systematic design approach was applied, which made it possible to establish the functional requirements and design parameters of the micro-grippers. The micro-grippers were installed on a manual manipulator to assess its performance in tasks such as moving micro-objects from one position to a desired position. The experiment showed that the micro-grippers function effectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.190-197
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• 2005

For precise micro-grooving and surface machining, a mechanism for creating elliptical vibration cutting (EVC) motion is proposed which uses two parallel piezoelectric actuators. And based on its kinematical analysis, variations of EVC path are investigated as a function of dimensional changes in the mechanism, phase difference and amplitude of excitation sinusoidal voltages. Using the proposed PZT mechanism, various types of two dimensional EVC paths including one dimensional vibration cutting path along the cutting direction and thrust direction can be easily obtained by changing the phase lag, the amplitude of the piezoelectric actuators, and the dimension of the mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.198-204
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• 2005

For precise micro V-grooving, ultrasonic elliptical vibration cutting (UEVC) is proposed using two parallel piezoelectric actuators, which are energized by sinusoidal voltages with a phase difference of 90 degrees. Experimental setup is composed of stacked PZT actuators, a single crystal diamond cutting tool, and a precision motorized xyz stage. It is found that the chip formed in the process of UEVC is discontinuous because of the periodic contacts and non-contacts occurring between the tool and workpiece. It is experimentally observed that the cutting force in the process of UEVC significantly reduces compared to the ordinary non-vibration cutting. In addition, the creation of burr during UEVC is significantly suppressed, which is attributable to the decrease in the specific cutting energy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.444-450
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• 2006

IPMC actuators have been developed with multi-walled carbon nanotubes(MWNT) and $Nafion^{\circledR}$ ionic polymers. MWNT with different diameters of $3{\sim}5,\;4{\sim}6$ and $10{\sim}15$ nm and length of $10{\sim}20{\mu}m$ were used to enhance the mechanical and electrical performances of IPMC actuators. Ultrasonic treatment and high speed mixing were used to disperse MWNT homogeneously in $Nafion^{\circledR}$ solution. The electroless plating technique is used to make electrodes on the both side of the composite membrane. SEM and TEM images were taken to characterize the surface and micro-structures of the composite actuators. In this study, improved IPMC actuators were developed and compared with respect to bending actuation performance and electrical power consumptions.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.4
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• pp.280-287
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• 2002

We present technical issues involved in the development of actuators and sensors for applications to high-precision Micro Electro Mechanical System (MEMS). The technical issues include fabrication uncertainty and noise disturbance, causing major difficulties for MEMS to achieve high-precision actuation and detection functions. For nano-precision actuators, we solve the fabrication instability and electrical noise problems using digital actuators coupled with nonlinear mechanical modulators. For the high-precision capacitive sensors, we present a branched finger electrodes using high-amplitude anti-phase sensing signals. We also demonstrate the potential applications of the nanoactuators and nanodetectors to high-precision positioning MEMS.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.103.2-103
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• 2001

In this paper, we discusses compliant actuators those are made of electrostrictive polymer. Electrostrictive polymer actuators(EPAs) are based on the deformation of dielectric elastomer polymer in the presence of an electric field. We address actual design and fabrication method of an actuator using the electrostrictive polymer. We have developed primitive prototypes of the actuator using elastic restoring force. And they actuators have 1 to 3 DOF, 1 DOF actuators are simple linear actuators and 3 DOF actuator has linear actuation and steering capability. They are simple in structure with lightweight, high trust, force and large stroke. Basic design principles and experimental procedures for confirming their performance will be introduced.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.429-429
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• 2000

Micro positioning mechanism is the key technology in many fields, such as scanning electron microscopy (SEM), x-ray lithography, mask alignment and micro-machining. In the paper, a 3DOF parallel-type micro-positioning mechanism is proposed. This mechanism uses piezo-actuators and Flexure hinge to control x, y and $\theta$ motion. It is shown both analytically and numerically that 2 DOF flexure hinge model was better precision than 1 DOF flexure hinge design.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.301-306
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• 2004

In this study, Dual servo mechanism with VCM(Voice Coil Motor) and PZT is designed for a high precision force and position control. We designed the VCM actuator and dual servo mechanism with leaf spring. VCM actuators, with their high linearity, simple structure, low weight, and high efficiency, are increasingly being used in micro-positioning applications. There are many kinds of VCM with a structure. VCM actuators are divided into two types by moving parts. One is moving magnet type and the other moving coil type. We described the properties of these two types of VCM. Design parameters of VCM are defined through the FEM simulation analysis of magnetic field and dynamic model of dual servo mechanism. These researches help to for decreasing loss in the air gap of VCM. We present dual servo mechanism is effective mechanism for a force control in hi h precision, properties of designed VCM.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.180-187
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• 2005

This paper is focused on the development of the flexible electrode for disc-type polymer actuators using Segmented Polyurethane(SPU). This paper consists of two parts. The one is about the mechanical property such as elastic modulus. these parameters mainly affect behaviors of polymer actuators and the other is about the electro-chemical property such as the surface resistance of the composite electrode affects the strength of electrostatic force, results in the deformation of polymer actuators. The Young's modulus was measured by UTM. As result, by increasing the modulus of a body of polymer actuators, the maximum displacement of polymer actuators are decreased. The surface resistance of the electrode was measured by 4 point probe system. Compared with the conductive silver grease, the displacement of polymer actuators using carbon black(CB) composite electrodes is comparably small but CB composite electrode should be the practical approach for the improvement of the performance of all-solid actuators, compared with another types of electrode materials.