Papers by Author: Tae Sam Kang

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Authors: In Pil Kang, Hyo Byung Chae, Ki Hoon Park, Kwang Joon Yoon, Li Li Xin, Tae Sam Kang
Abstract: A smart material actuator is required for a smart structure having multifunctional performance. Among the smart material actuators, piezoelectric actuator is known for its excellent large force generation in broad bandwidth in a compact size. However it needs relatively large actuation voltage requiring a bulky hardware system. This study is mainly concerned to develop a self-powered miniaturized piezoelectric actuator driver (MIPAD) controlled by a radio controller for small sized piezoelectric smart structures. It can receive command from other microprocessors or a remote radio controller. We designed a real hardware and it demonstrated good performances even though the driving system was very small. The MIPAD is expected to minimize the weight and size of the piezoelectric actuator system and it can be easily embedded into mobile smart structures.
Authors: Tae Sam Kang, Gi Gun Lee, Jung Hwan Kim
Abstract: Multi-rotor is one of the emerging Unmanned Aerial Vehicle platforms. This paper covers the design, fabrication, modeling and testing of a quad-rotor control system. To take into account the salient nonlinearities, a model with six degrees of freedom nonlinear dynamics and some linear approximation of the aerodynamic part are used when extracting a linear model and designing a attitude controller. We obtained a linear model from experimental data using system identification method and developed attitude control algorithm. The control algorithm was realized using an on a board microprocessor and verified through experiment in real environment.
Authors: Sang Kyung Sung, Tae Sam Kang, Chul Hyun, Byeung Leul Lee, Jang Gyu Lee, Chan Gook Park, Young Jae Lee
Abstract: In this paper, presented are design, analysis, and experimental result of a tunable surface micromachined resonant accelerometer, ACRC-RXL. Also fabrication process of mechanical structure is illustrated. We used 40[μm] thick epitaxially grown polysilicon as structural layer and sealing area. With the exception of the CMP process, for smoothing the bonding area, the fabrication processes are simple as the conventional surface micromachining process. Experimental results show that the developed accelerometer has a performance of bias stability about 0.5mg and dynamic range over 10g.
Authors: Woon Tahk Sung, Seong Hyok Kim, Jang Gyu Lee, Tae Sam Kang
Abstract: In this paper, presented are the design and the fabrication of the novel bulk-micromachined gyroscope with its detection and control circuit. The proposed structure is designed to have good properties such as heavy proof mass, a large movement and high moving velocity of the proof mass at an operating frequency. Despite of an appropriate design of the proof mass and comb electrodes, the high-Q property and the capacitance measurement scheme inevitably bring on nonlinear property and limited bandwidth of the system. Moreover, temperature variation degrades the stability of the performance. In this paper, we adopt a feedback control scheme to achieve a linear output and a less sensitive operation to the temperature variation. Through experiments, it is confirmed that the designed gyroscope and the control circuit achieve performances of wide input range of 1,000 deg/sec and bandwidth of 80 Hz.
Authors: Woon Tahk Sung, Hyung Taek Lim, Tae Sam Kang, Jang Gyu Lee, Young Jae Lee
Abstract: This paper presents a design and performance tests of in-plane gimbal-structured Z-axis gyroscope. The device is manufactured by conventional surface micro machining process using 15µm-thickness epitaxially grown polysilicon. The total size of the device is 4.8mm x 4.8mm in area including 1mm x 1mm core gyro structure and pads for wire bonding. It is designed as two-gimbaled structure which separates inner and outer gimbals. This leads two nearly identical modes of gyroscope, i.e. driving and sensing mode, to mechanically decoupled ones, resulting in enhanced performance. Experiments are accomplished through frequency analysis and dynamic tests using a detection circuit, a vacuum chamber and a rate table. Through experiments, it is confirmed that the designed gyroscope has 0.003 deg/sec resolution, 0.00095 deg/sec/ Hz noise equivalent density, 0.57 % FSO nonlinearity error and 0.02 deg/sec bias stability.
Authors: Chul Hyun, Jang Gyu Lee, Tae Sam Kang
Abstract: This paper presents a surface micro-machined differential resonant accelerometer (DRXL) by using the epitaxially grown thick polysilicon process. The proposed DRXL utilizes the electrostatic stiffness changing effect of an electrostatic torsional actuator. This device produces a differential digital output proportional to an applied acceleration. For a self-generated and self-sustained oscillation of the resonator, a feedback oscillation loop is designed, implemented, and applied to the DRXL chip. The oscillation loop is designed using an analytical result based on the describing function method. Using the implemented self-sustaining oscillation loop, pecifications of sensor performance are obtained by various performance tests. These results show quite an improved quality factor and resolution compared to that of the sensing device only. And we obtained more stable output frequency responses.
Authors: Chul Hyun, Jang Gyu Lee, Tae Sam Kang
Abstract: This paper presents an oscillation loop for an INS (Inertial Navigation System) grade, surface micro-machined resonant type accelerometer. This resonant type sensor utilizes the electrostatic stiffness changing effect of an electrostatic actuator. This device produces a frequency output upon an applied acceleration. A closed loop system called self-sustained oscillation loop is prerequisite for its operation as a resonant accelerometer. A self-sustained oscillation loop induces the system’s dynamic states into its primary mode, thus keeps track of its resonant state under applied acceleration or perturbation. For this, a simple self-sustained oscillation loop is designed and the feature of the loop is analyzed in the viewpoint of nonlinear dynamic system. From the standpoint of feedback control system, both determination of resonance point and its stability analysis are required. In the actual system, which has several noise sources, noise can affect the output resonant frequency. We analyzed the effect of a noise on oscillation frequency. Finally, simulation and experimental result is given
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