• Journal of Institute of Control, Robotics and Systems
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• v.15 no.11
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• pp.1108-1114
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• 2009

Mobility is one of the most important features for a guard robot since it should be operated in rough places. A wheel-based mobile robot capable of jumping is an appropriate structure for a guard robot because it can easily satisfy the requirements for small guard robots. The jumping robot can reach a higher place more rapidly than other locomotion methods. This research proposes a small robot equipped with the jumping mechanism based on the conical spring with the variable length endtip. The variable length endtip enables the independent control of the jump force and jump angle which are related to the jump height and jump distance, respectively. Various experiments demonstrated that the proposed jumping mechanism can provide the independent control of jump force and jump angle, and improve the mobility of a small robot to overcome an obstacle. Furthermore, a combination of the jumping mechanism and the PSD sensor to measure the distance to the step enable the jumping robot to autonomously climb stairs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.2007-2013
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• 1999

A Newly proposed control methodology applied to the aeroelastic system experiencing flutter is investigated and its performance is verified experimentally. The flexible cantilever beam slicked with piezofilm sensor and piezoceramic actuator is modelled in physical domain. Dynamic moment equation for the system is derived via Ito's stochastic differential equation and F-P-K equation. Also system's characteristics in stochastic domain is analyzed simultaneously. LQG controller is designed and used in physical and stochastic domain. It is shown experimentally that the vibration of beam is controlled effectively by designed LQG controller in physical domain. By comparing the result with that of LQG controller designed in stochastic domain, it is shown that the new control method, called Heo-stochastic control technique, has better performance as a controller.

• Corrosion Science and Technology
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• v.16 no.4
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• pp.194-200
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• 2017

Stress-corrosion cracking (SCC) of alloy 600 and alloy 800 in 0.5 mol/L thiosulfate solution during constant strain was investigated using electrochemical noise (EN) combined with 3-D microscope techniques. The in-situ morphology observation and EN results indicate that the SCC process could be divided into three stages: (1) passive film stabilization and growth, (2) crack initiation, (3) and crack growth. Power Spectral Density (PSD) and the probability distribution obtained from EN were used as the "fingerprint" to distinguish the different processes. During passive film stabilization and growth, the current noise signals resembled "white noise": when the crack initiated, many transient peaks could be seen in the current noise and the wavelet energy at low frequency as well as the noise resistance decreased. After crack propagation, the noise amplitudes increased, particularly the white noises at low and high frequencies ($W_L$ and $W_H$) in the PSDs. Finally, the detection of metal structure corrosion in a simulated sea splash zone and pipeline corrosion in the atmosphere are established.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.4
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• pp.237-243
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• 2014

In this paper we present an real-time obstacle avoidance technique of autonomous mobile robot with steering system and implementation of user interface for mobile devices with Android platform. The direction of autonomous robot is determined by virtual force field concept, which is based on the distance information acquired from 5 ultrasonic sensors. It is converted to virtual repulsive force around the autonomous robot which is inversely proportional to the distance. The steering system with PD(proportional and derivative) controller moves the mobile robot to the determined target direction. We also use PSD(position sensitive detector) sensors to supplement ultrasonic sensors around dead angle area. The mobile robot communicates with Android mobile device and PC via Ethernet. The video information from CMOS camera mounted on the mobile robot is transmitted to Android mobile device and PC. And the user can control the mobile robot manually by transmitting commands on the user interface to it via Ethernet.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.260-265
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• 2003

A noncontact optical system that can measure displacement or vibration of an object is designed by employing the oblique ray method. By using a single convex lens which serves as both the input and output lenses, we made the optical system very compact and reliable. In addition, the bandwidth of the vibration measurement is more than 100 KHz by using the position-sensitive detector as the beam position sensor. The resolution and capture range of the system are $\pm$1 ${\mu}{\textrm}{m}$ and 1100 ${\mu}{\textrm}{m}$, respectively. As a sample test, the vibrations of a speaker and a rotating compact disc surface were measured.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.5
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• pp.219-224
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• 2015

In this paper, the designed fish robots DOMI ver1.0 is researched and development for aquarium underwater robot. The presented fish robot consists of the head, 1'st stage body, 2nd stage body and tail, which is connected two point driving joints. The model of the robot fish is analysis to maximize the momentum of the robot fish and the body of the robot is designed through the analysis of the biological fish swimming. Also, Lighthill was applied to the kinematics analysis of robot fish swimming algorithms, we are applied to the approximate method of the streamer model that utilizes techniques mimic the biological fish. The swimming robot has two operating mode such as manual and autonomous operation modes. In manual mode the fish robot is operated to using the RF transceiver, and in autonomous mode the robot is controlled by microprocessor board that is consist PSD sensor for the object recognition and avoidance. In order to the submerged and emerged, the robot has the bladder device in a head portion. The robot gravity center weight is transferred to a one-axis sliding and it is possible to the submerged and emerged of DOMI robot by the breath unit. It was verified by the performance test of this design robot DOMI ver1.0. It was confirmed that excellent performance, such as driving force, durability and water resistance through the underwater field test.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1417-1422
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• 2005

Among the sensors mainly used for displacement measurement, there are a linear CCD(Charge Coupled Device) and a PSD(Position Sensitive Detector) as a non-contact type. Their structures are different very much, which means that the signal processing of both sensors should be applied in the different ways. Most of the displacement measurement systems to get the 3-D shape profile of an object using a linear CCD are a computer-based system. It means that all of algorithms and mathematical operations are performed through a computer program to measure the displacement. However, in this paper, the developed system has microprocessor and other digital components that make the system measure the displacement of an object without a computer. The thing different from the previous system is that AVR microprocessor and FPGA(Field Programmable Gate Array) technology, and a comparator is used to play the role of an A/D(Analog to Digital) converter. Furthermore, an ATC(Automatic Threshold Control) algorithm is applied to find the highest pixel data that has the real displacement information. According to the size of the light circle incident on the surface of the CCD, the threshold value to remove the noise and useless data is changed by the operation of AVR microprocessor. The total system consists of FPGA, AVR microprocessor, and the comparator. The developed system has the improvement and shows the better performance than the system not using the ATC algorithm for displacement measurement.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.470-477
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• 2009

Modular reconfigurable robots with physical docking capability easily adapt to a new environment and many studies are necessary for the modular robots. In this paper, we propose a vision-based fuzzy autonomous docking controller for the modular docking robots. A modular docking robot platform which performs real-time image processing is designed and color-based object recognition method is implemented on the embedded system. The docking robot can navigate to a subgoal near a target robot while avoiding obstacles. Both a fuzzy obstacle avoidance controller and a fuzzy navigation controller for subgoal tracking are designed. We propose an autonomous docking controller using the fuzzy obstacle avoidance and navigation controllers, absolute distance information and direction informations of robots from PSD sensors and a compass sensor. We verify the proposed docking control method by docking experiments of the developed modular robots in the various environments with different distances and directions between robots.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.25-35
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• 2006

The purpose of this study was to investigate the shock attenuation mechanisms while varying the loads in a backpack during drop landing. Ten subjects (age: $22.8{\pm}3.6$, height: $173.5{\pm}4.3$, weight: $70.4{\pm}5.2$) performed drop landing under five varying loads (0, 5kg. 10kg. 20kg. 30kg). By employing two cameras (Sony VX2100) the following kinematic variables (phase time, joint rotational angle and velocity of ankle, knee and hip) were calculated by applying 2D motion analysis. Additional data, i.e. max vertical ground force (VGRF) and acceleration, was acquired by using two AMTI Force plates and a Noraxon Inline Accelerometer Sensor. Through analysing the power spectrum density (PSD), drop landing patterns were classified into four groups and each group was discovered to have a different shock attenuation mechanism. The first pattern that appeared at landing was that the right leg absorbed most of the shock attenuation. The second pattern to appear was that subject quickly transferred the load from the right leg to the left leg as quickly as possible. Thus, this illustrated that two shock attenuation mechanisms occurred during drop landing under varying load conditions.