Hyoyoung Kim

Development of a Nanoprecision 3-DOF Vertical Positioning System With a Flexure Hinge

This paper describes the conceptual design of an ultraprecision 3-DOF (Z, Ox, Oy) vertical positioning system with nanometer precision. The vertical out-of-plane positioning system can be used for various nanoalignment applications, such as optical instrument alignment. The proposed vertical positioning system is driven by three piezoelectric (PZT) actuators and is guided by three rotationally symmetric hinges. Because the displacement generated by a PZT actuator is very small, the proposed system also includes an amplification hinge mechanism. Because the relationships between the variables of the hinge parameters and system performance levels are complicated, an optimization procedure to obtain optimal design parameters, which maximize the system bandwidth, is developed. Based on the solution to the optimization problem, the design of a vertical positioning system and finite-element-method simulation results are presented. Finally, the stage is manufactured and tested for verification. The stroke of the translational movement is 190 mm, and the stroke of the rotational movement is 0.5 mrad, whereas their in-position stability levels are ±2 nm and ±20 nrad and resolutions are 5 nm and 80 nrad, respectively. The settling time is less than 45 ms.

Development of a novel 3-degrees of freedom flexure based positioning system

Flexure mechanisms have been widely used for nanometer positioning systems. This article presents a novel conceptual design of an ultra-precision 3-degrees of freedom (XYθ(Z)) positioning system with nanometer precision. The main purpose of this novel stage design is for the application of measurement equipment, in particular biological specimens. The stage was designed as a hollow type and with a compact size for the inverted microscope. This stage includes piezoelectric transducer actuators, double compound amplification mechanisms, moving plate, and capacitor sensors. The double compound amplification mechanism was designed using a mathematical model and analyzed by the finite element method. Since the relationship between the variables of the hinge parameters and system performances are complicated, an optimization procedure was used to obtain the optimal design parameters, which maximized the system bandwidth. Based on the solution of the optimization problem, the design of the stage and FEM simulation results are presented. Finally, the stage was manufactured and tested.

Optimal design and experiment of a three-axis out-of-plane nano positioning stage using a new compact bridge-type displacement amplifier

This paper presents the development of a new compact three-axis compliant stage employing piezoelectric actuators and a new flexure structure. A proposed stage works out-of-plane (Z, θx, θy) direction. The stage consists of 4 amplification flexures mounted piezoelectric actuators. New structure of flexure reduces height and enhances dynamic performance of stage. To certify excellent performance of the stage, comparison accomplished between conventional amplification flexure and new compact bridge type flexure. Modeling and optimal design of new type nano positioning stage performed. The optimal design is executed on the geometric parameters of the proposed flexure structure using Sequential Quadratic Programming. Experiments are carried out to verify the static and dynamic performance of the stage. The proposed out-of-plane nano-positioning stage has a Z-directional motion range 190 μm and a θx, θy-directional motion range ±2 mrad. The resolution of the stage is 4 nm, 40 nrad, and 40 nrad in the Z-, θx-, and θy-directional motions, respectively. The size of stage is 150 × 150 × 30 mm(3).

Development of a mobile robot controlled by three motors for a hostile environment

In this study a hybrid legged/wheeled mobile robot, KAMOBOT, is developed. The mobile robot has a six-legged cylindrical configuration, each leg of which is equipped with a wheel at the bottom. The robot can go up and down stairs, go over obstacles, move along curvilinear paths and rotate around its geometric center. Such maneuverability can be achieved by using only three electric motors. In this study several gate modes are analyzed and algorithms for gate control are presented.<<ETX>>

Note: Development of a compact aperture-type XYθz positioning stage

In this paper, we propose a new in-plane XYθz nano-positioning stage that utilizes piezoelectric actuators and flexure mechanisms. The proposed stage has an aperture and is compact, which facilitates its application in measurement equipment, especially those used for biological specimens. The stage has four piezoelectric actuators and four bridge-type flexure mechanisms, which are used to amplify the small motions produced by the piezoelectric actuators. This paper describes the modeling and design optimization of the stage, which has X- and Y-direction motion ranges of 300 μm and a θz-direction motion range of ±3.9 mrad. The stage measures 150 × 150 × 23 mm, and its aperture is 50 × 50 mm.

Development and optimization of a novel 3-DOF precision flexure stage

This article presents a novel concept design and optimal design of an ultra-precision XYθz flexure and PZT stage with nanometer accuracy. The stage consists of a regular triangle monolithic flexure mechanism with three piezoelectric actuators, and the stage uses a parallel mechanism. Since the relationship between the variables of the hinge parameters and system performances are complicated, it is very difficult to set design variables manually. Therefore, optimal design is used. Using the optimal design results, a FEM simulation was performed. The stage was designed to simultaneously attain ±50um in the X and Y directions and ±0.025° in the yaw direction, and have a first resonant frequency of 207 Hz in the yaw direction The main purpose of this novel stage is to design appropriate measurement equipment; for biological specimens in particular, the stage was designed as a hollow type and with a compact size (330 mm × 330 mm × 50 mm).

Improving dental service via communication during treatment

Communication between dental service providers and their patients is a key element of service quality. However, it is clear, and surveys confirm, that verbal communication during treatment is difficult for patients. In this paper, we discuss the development and service quality evaluation of a handheld device enabling limited communication during dental treatment. The shape and function of the device were determined using insights from the literature, surveys and Axiomatic Design theory. The device, which contains several buttons and speakers/headphones, emits sounds communicating pain, a need for suction and other essential issues. In this way, a patient with dental instruments in their mouth can clearly and quickly express simple needs. To deduce the service quality improvement associated with using the device, SERVQUAL surveys were conducted on a population of 175 dental patients. Based on statistical significance scores from Wilcoxan tests, we determined that the perception of both communication and service provider response time improved when using the device. The overall service quality did not demonstrate a statistically significant change; we attribute this to the fact that there were statistically significant decreases in service timeliness and privacy on account of the longer survey and presence of data collection observer associated with using the device. As such, we conclude that the device may be a useful tool to improve dental service quality.