Search

Communication is a key aspect of modern life. Unfortunately, when natural disasters occur, the communication system and infrastructure of a city may be partially or even completely destroyed. In this case, communication becomes a crucial part of search-and-rescue missions. This study develops an aerial communication relay platform as an effective solution for communication loss during a natural disaster. The model used considers the aircraft altitude and attitude, which affect the energy acquisition and consumption, and the signal fading effects. The flight path is planned by adopting a nonlinear optimization technique, i.e., the Hermite-Simpson collocation method. For a realistic communication model regarding urban signal loss and path propagation, the building deployment of an area of radius 2km in two cities in South Korea (Seoul and Jeonju) was obtained. Simulation experiments for the different urban environments were performed to test the communication reliability, focusing on the relation between the unmanned aerial vehicle and ground users. Through the simulation, the optimal flight paths in high-rise urban and urban microcell environment were obtained. The obtained results were later compared with a baseline simulation composed of a steady-flight circular path. The generated flight path proves the feasibility of endurance flights for low-altitude communication aid aircrafts using a unified model for signal fading alongside solar power energy acquisition into the case study.

Achieving the long-endurance of a solar-powered unmanned aerial vehicle is difficult under a limited amount of energy and specific meteorological environments. Therefore, it is essential to manage the energy used by a solar-powered UAV during a mission. In this paper, a framework for energy-based path planning for a solar-powered UAV is presented. In order to generate the optimal path in terms of energy in a specific meteorological environment, the energy model of a solar-powered UAV is considered with regard to wind field. Additionally, the optimal energy path is examined through the optimal control technique. The optimal path is then applied to some case studies regarding solar-powered UAVs, and evaluated in order to verify the feasibility of the proposed approach. The optimization results show that the resulting path is indeed the optimal path, which increases the endurance of a flight and takes weather conditions into accounts. The proposed approach is also expected to find optimal paths in accordance with real weather environments and/or various weather situations.

The energy requirements of a solar-powered exploration rover constrain the mission duration, traversability, and tractive capability under the given limited usable power. Thus, exploration rover design, more specifically, rover wheel design (related to considerable energy consumption in driving), plays a significant role in the success of exploration missions. This paper describes the modeling of an operational environment and a multi-body dynamics (MBD) simulation tool based on wheel-terrain interaction model to predict the dynamic behavior on a digital elevation model (DEM) map. With these simulation environments, a multidisciplinary optimal wheel design methodology, integrating the MBD simulation tool and non-dominated sorting genetic algorithm-II (NSGA-II), is developed. Design parameters are chosen through sensitivity analysis. These multi-objective optimizations in dynamic states are conducted to obtain the optimal wheel dimension that meet the limited power condition with maximal tractive capability under the given operational environment. Furthermore, numerical and experimental verification using a single wheel testbed on lunar simulant are conducted to convincingly validate the derived optimization results. Finally, these results reveal that the proposed design methodology is an effective approach to deciding the best design parameter among a large variety of candidate design points considering the restricted power requirement.

Electronic Travel Aids (ETAs) improve the mobility of visually-impaired persons, but it is not easy to develop an ETA satisfying all the factors needed for reliable object detection, effective notification, and actual usability. In this study, the authors developed an easy-to-use ETA having the function of reliable object detection and its successful feedback to the user by tactile stimulation. Seven ultrasonic sensors facing in different directions detect obstacles in the walking path, while vibrators in the tactile display stimulate the hand according to the distribution of obstacles. The detection of ground drop-offs activates the electromagnetic brakes linked to the rear wheels. To verify the feasibility of the developed ETA in the outdoor environment, walking tests by blind participants were performed, and the evaluation of safety to ground drop-offs was carried out. From the experiment, the feasibility of the developed ETA was shown to be sufficient if the sensor ranges for hanging obstacle detection is improved and learning time is provided for the ETA. Finally, the light-weight and low cost ETA designed and assembled based on the evaluation of the developed ETA is introduced to show the improvement of portability and usability, and is compared with the previously developed ETAs.

Abnormal changes in the ST segment of an electrocardiogram (ECG) are very important diagnostic parameters for detecting myocardial ischemia. ST segment analysis requires a long-term ECG recording because of the transient change of the ST segment. Deviations of the ST segment are generally related to myocardial abnormality. In this study, we classify the ST segments by their morphology. First, a set of reference ST shapes is given. The ECG analysis algorithm developed in this study consists of feature point detection and ST shape classification. S wave and J-point detection are performed during the process of feature point detection, and the proposed algorithm classifies the STs into reference ST shapes. To improve the performance of ST shape classification, the rules for the trend of previous beats and the shape type of previous beats are used. The results from the proposed algorithm can provide information on the change in the ST shape. In our evaluation for classification of STs by their morphology using the test ECG data, the global correct rate was 83.14%. The best accuracy of existing ST level detection algorithms are 90% and over. However, considering that ST level detection algorithms cannot show the change of ST morphology; and that there are no studies about the classification of STs by their morphology using a reference ST set, the proposed algorithm is worthy of note.

ECG is used on purpose to keep good health or monitor cardiac function of aged person as well as on purpose to diagnose the disease of heart patients. The ambulatory ECG monitoring system under guarantee of safety and accuracy is very efficient to prevent the progress of heart disease and sudden death. These systems can detect the temporary change of ECG that is very significant to diagnose heart disease such as myocardial ischemia, arrhyamia and cardiac infarction. In this paper, we describe the ECG signal analysis algorithm and measurement device for ECG monitoring. The authors designed a small-size portable ECG device that consisted of instrumentation amplifier, micro-controller, filter and RF module. The device measures ECG with four electrodes on the body and detects QRS complex and ST level change in realtime. Also it transmits the measured signals to the personal computer. The developed software for ECG analysis in personal computer has the function to detect the feature points and ST level changes.

In walking guide robot, a guide vehicle detects an obstacle distribution in the walking space using range sensors, and generates a 3D grid map to map the obstacle information and the tactile display. And the obstacle information is transferred to a blind pedestrian using tactile feedback. Based on the obstacle information a user plans a walking route and controls the guide vehicle. The algorithm for 3D detection of an obstacle distribution and the method of mapping the generated obstacle map and the tactile display device are proposed in this paper. The experiment for the 3D detection of an obstacle distribution using ultrasonic sensors is performed and estimated. The experimental system consisted of ultrasonic sensors and control system. In the experiment, the detection of fixed obstacles on the ground, the moving obstacle, and the detection of down-step are performed. The performance for the 3D detection of an obstacle distribution and space mapping is verified through the experiment.

In this paper, firstly, we propose a generating method of the 3-D obstacle map using ultrasonic sensors. Secondly, we try to find the necessary stimulation conditions of compact tactile display device for effective transfer of obstacle information. The final goal of this research is the development of a walking guide system for the blind to walk safely. The walking guide system consists of a guide vehicle for the obstacle detection and a tactile display device for the transfer of the obstacle information. The guide vehicle, located in front of the walking blind, detects the obstacle using ultrasonic sensors. The processed information makes an obstacle map and transmits safe path and emergency situation to the blind by the tactile display. The tactile display device, located in the handle which is connected with the guide vehicle by cane, offers the processed obstacle information such as position, size, moving, shape of obstacle and safe path, etc. The concept of a walking guide system with tactile display is introduced, and experiments of 3-D obstacle detection and tactile perception are carried out and analyzed.

Recently, unmanned aerial vehicles (UAVs) are applied to various fields, and the demand of UAV has also been increased. Achieving long endurance of a UAV is very important to perform a variety of tasks. A solar UAV is the one way for long endurance. However, there is damage or loss of solar UAV for the flight test. In this study, the ground testbed is designed for replicating flight motion of the solar powered unmanned flying vehicle (UFV) on the ground to minimize the practical constraints. The testbed evaluates the performance of the main parts such as solar module, MPPT, battery packs and verifies the feasibility of the long endurance flight. The evaluation system can monitor the energy flow by the measurement of the energy production and the consumption according to flight motion. And the experiment result was compared with the flight simulation using MATLAB for validation.

Endurance flight capability of solar powered UAV is an important element in performing various missions. In the limited conditions such as solar cell efficiency or sunray radiant quantities, an efficient operation is required to achieve continuous flight. In order to improve endurance flight capability of solar powered UAV, this study tried to optimize flight path through the use of gravitational potential energy by controlling flight altitude and through aircraft attitude control. The energy model includes the solar position, aircraft attitude, and aerodynamics characteristics, and the influence of air density and atmospheric transmittance was considered according to flight altitude change. Through a case study, energy optimization was performed for endurance flight. As a result of simulation, compared to level flight, energy acquisition increased and battery use decreased, which indicates that flight path optimization is effective for improvement of endurance flight capability.

Recently UAVs are applied in various fields, such as monitoring forest fires, border surveillance and so on. To achieve long-term endurance of UAV is important for various mission purposes. The solar UAV is one way for long-term endurance. The development and test of solar UAV has practical constraints in real flight evaluation because of its limitation of technical infrastructure. In this study, the virtual flight evaluation system is designed for replicating real flight motion of the solar powered UAV to evaluate a flight performance. The virtual flight system evaluates the performance of the main parts, such as solar module, MPPT, battery packs and verifies the feasibility of long-term endurance. The virtual flight system can monitor the energy flow by the measurement of energy production and consumption according to flight motion. And the experimental result was compared with the simulation using MATLAB for validation.

The experiment of the shape recognition for a tactile display is carried out and analysed in this paper. The purpose of this research is the development of a tactile stimulator array to represent the obstacle information for the visually impaired to walk safely. As a first step of this research, we investigate the characteristics of tactile stimuli and design the experimental system for the physiological characteristic test based on the investigated results. In order to determine the appropriate and optimal range of the actuating frequency and displacement for the tactile stimulation array, the psychophysical experiment for the threshold of perception and recognition ability of multi-stimulation with some shapes are carried out by the estimation of the subject group. As a result the appropriate tactile stimulus intensity and frequency of the tactile stimulation array to recognize arbitrary line shapes effectively are discussed and derived.

Myocardial ischemia is a disorder of cardiac function caused by insuficient blood flow to the muscle tissue of the heart. We can diagnose myocardial ischemia by observing the change of ST-segment, but this change is temporary. Our primary purpose is to detect the temporary change of the 57-segment automatically In the signal processing, the wavelet transform decomposes the ECG(electrocardiogram) signal into high and low frequency components using wavelet function. Recomposing the high frequency bands including QRS complex, we can detect QRS complex more easily. Amplitude comparison method is adopted to detect QRS complex. Reducing the effect of noise to the minimum, we grouped ECG by 5 data and compared the amplitude of maximum value. To recognize the ECG .signal pattern, we adopted the polynomial approximation partially and statistical method. The polynomial approximation makes possible to compare some ECG signal with different frequency and sampling period. The ECG signal is divided into small parts based on QRS complex, and then, each part is approximated to the polynomials. After removing the distorted ECG by calculating the difference between the orignal ECG and the approximated ECG for polynomial, we compared the approximated ECG pattern with the database, and we detected and classified abnormality of ECG.

This paper represents the development of an array-type flexible tactile sensor using PVDF(polyvinylidene fluoride) film and flexible circuitry. The tactile sensor which has taxels is made by using PVDF film and FPC(flexible printed circuit) technique. Experimental results on static and dynamic properties are obtained by applying arbitrary forces and frequencies generated by the shaker. In the static characteristics, the threshold and the linearity of the sensor are investigated. Also dynamic response of the sensor subjected to the variable frequencies is examined. The signals of a contact force to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the outputs of the sensor are visualized on a personal computer, the shape and force distribution of the contacted object are obtained using two and three-dimensional image in real time. The reasonable performance for the detection of contact state is verified through the experiment.

The prototype of the tactile sensor which has 8 × 8 array using piezoelectric film was fabricated. In the fabrication procedure, the electrode patterns and the common electrode of the thin conductive tape are attached to the both sides of the 28 um thickness piezoelectric film using conductive adhesive. The sensor is covered with polyester film for insulation and attached to the rubber base for a stable structure. The proposed fabrication method is simple and easy to make the sensor. The sensor has the advantages in the implementing for practical applications because its structure is flexible and the shape of the each tactile element can be designed arbitrarily. The signals of a contact force to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the output of the sensor are visualized in a personal computer, the shape and force distribution of the contact object are obtained. The reasonable performance for the detection of the contact state was verified through the sensing examples.

The problem-solving ability of a human in manual control is considered. The purpose of the manual control is the positioning of the two-link arm with a free joint. This kind of manipulator are getting popular recently because of its simplicity. The control of the manipulator, however, is difficult because the motion is governed by a set of nonlinear equations. A real-time simulator is used to perform the experiment of manual control. It is concluded that a human can find some satisfactory control patterns after enough training. These results are interesting from the theoretical point of view, they suggest a possible theoretical approach to this difficult control problem.

In this paper we discuss the non-linear motion of a conservative two-link system based on first integrals. In the analysis of the motion, the constant of the first integral plays an important role. First, we show that the free motion can be classified into two types by investigating the integral constant. The one is oscillation and the other is rotation. We also show that the forced motion actuated at the second joint can be expressed schematically as a variation of the integral constant. Also, the dynamic characteristics of the forced motion are presented based on the proposed analytic approach. This analytic approach may be applied to similar non-linear dynamical systems which have the first integrals.

The development of the real-time microvision system with three-dimensional (3D) structure is introduced. A number of two-dimensional LSIS (2D-LSIs) which play amplifying and converting image signal and some arithmetic operations are fabricated vertically. The microvision system transfers the two-dimensional (2D) image data arrays as it is using high density vertical interconnections. The image information signals are processed in parallel in each LSI and the processing is performed in pipeline over all the system. In fabrication, grinding and chemical-mechanical polishing techniques are used to thin the wafer to 30 ym. The thinned wafer with buried interconnections is bonded vertically to a thick wafer through microbumps after careful alignment by the wafer aligner with the alignment tolerance of 1 Mm. The real-time microvision system with 3D structure can be fabricated by repeating such sequence.

In this paper, we discuss the position control of a two-link arm. The first joint is a free one and the second joint is an active one. The system in this case is uncontrollable locally; thus we investigate the motion characteristics of the system globally. As a result, we find that the system can be controlled without using any additional equipment when the system has friction at the free joint. Two control algorithms using the friction torque at the free joint are presented with numerical examples. One algorithm controls the joints separately and the other controls the joints simultaneously.

ECG is used on purpose to keep good health or monitor cardiac function of aged person as well as on purpose to diagnose the disease of heart patients. The ambulatory ECG monitoring system under guarantee of safety and accuracy is very efficient to prevent the progress of heart disease and sudden death. These systems can detect the temporary change of ECG that is very significant to diagnose heart disease such as myocardial ischemia, arrhythmia and cardiac infarction. In this paper, we describe the ECG signal analysis algorithm and measurement system for ECG monitoring. The designed small-size portable ECG device consisted of instrumentation amplifier, micro-controller, filter and RF module. The developed device measures ECG with four electrodes in the body and detects QRS complex and ST level change in real-time. Also it transmits the measured signal to the personal computer. The developed software for ECG analysis in personal computer has the function to detect the feature points and ST level change.

Zhou and his co-workers proposed an "intelligent controller" that simulates the control behavior of a human operator. The controller has multiple control modes to simulate a human operator switching several control actions according to the state of a target plant. In this paper, we discuss an application of the intelligent controller to swing up a one-link pendulum under driving torque limitation. To design the controller, we examine the action of a human operator who controls the swing-up motion of a one-link pendulum, and obtain three control modes with six parameters. Then the parameters are adjusted using a pendulum simulation system. The experimental results show that the designed controller achieves successful swing-up control even if the plant parameters are changed.

In walking guide system for a blind pedestrian, it is needed to detect an obstacle distribution in walking space not only 2D but space including pendent and/or protruded obstacles, and feedback to the blind for safe walking. The obstacle information is transferred to a blind pedestrian by a tactile stimulation. Based on the obstacle information a user plans walking route, and controls the walking guide system. In this paper, the methods for a 3D obstacle detection using ultrasonic sensors and mapping to an array type tactile stimulator are proposed. The experiment for the 3D detection of an obstacle distribution using ultrasonic sensors is performed and estimated. The experimental system consisted of ultrasonic sensors and control system. In the experiment, the detection of obstacles on the ground and the detection of down step are performed. The performance for the 3D detection of obstacle distribution and mapping for tactile stimulation are verified through the experiment.

In this paper, a preliminary experimentation is carried out to investigate the necessary stimulation conditions for a pattern display that may be used for the blind to display obstacle distribution. To design an efficient vibrotactile display device of array-type and compact size, the effect of some main parameters, such as the amplitude and frequency of vibration and the spacing and quantity of vibrated pins on vibrotactile perception, should be considered. Through experiment and analysis, the minimal amplitude of vibrating stimuli and the spacing effect on the perception of vibrotactile pattern are investigated and discussed. Also an appropriate type of actuator satisfying the requirements of a compact tactile display device for the effective transfer of pattern information is discussed.

In this paper, the concept of a walking guide system with tactile display is introduced, and experiments of 3-D obstacle detection and tactile perception are carried out and analyzed. The algorithm of 3-D obstacle detection and the method of mapping the generated obstacle map and the tactile display device for the walking guide system are proposed. The experiment of the 3-D detection for the obstacle position using ultrasonic sensors is performed and estimated. Some design guidelines for a tactile display device that can display obstacle distribution is discussed.

The morphological change of ECG is the important diagnostic parameter to finding the malfunction of a heart. Accordingly, physicians make theirs effort to find the change of ST segment level, RR interval, PR interval, P wave, T wave, etc. Generally ST segment deviation and T deviation is concerned with myocardial abnormality. The aim of this study is to detect the change of ST and T in shape using a polynomial approximation method. The developed algorithm makes the least squares curve for the data between S wave and T wave in ECG and calculates the variance of ST and T shape. An approximate curve of ST is represented by one polynomial over the whole ST or three polynomials for the segmented ST by three parts. We applied the developed algorithm to the ECGs in European ST database. The algorithm detects the relative change of ST shape based on the reference ST that is the average ST about 10 ST from the beginning of test ECG. We compared the annotations checked by cardiologists with the result of our algorithm. From the results of the auto-analysis using our algorithm, we could acquire the information about the place including ST and T episode in the test ECG.

ST segment is the most important diagnostic parameter to finding myocardial ischemia. Generally physicians make theirs effort to find the change of ST level and shape in ECG to diagnose myocardial ischemia. Most of algorithms that have been developed until now place importance on the ST segment depression and elevation. However, ST change in shape is also good parameter to find a heart disease and it should be considered prudently. The aim of this study is to detect the change of ST in shape using a polynomial approximation method. The developed algorithm finds the least squares curve for the data between S wave and T wave in ECG and calculates the variance of ST shape. An approximate curve of ST is represented by one polynomial over the whole ST or three polynomials for the segmented ST by three parts. The algorithm considers only the relative change of ST shape based on the reference ST, normal shape typically. From the results of the developed algorithm, we can acquire visually the information about the place to include the change of ST shape in the test ECG provided by European ST database.

In this paper, we describe the hardware configuration for ambulatory ECG monitoring device and the algorithm for detection of ST shape change. Ambulatory ECG recordings are available for diagnosis of heart diseases such as myocardial infarction, arrhythmia, etc. It especially is important to detect the transient ECG pattern changes. The detection of transient ST change caused by myocardial ischemia is one of the reasons why ambulatory ECG monitoring system is necessary. We designed a small-size portable ECG device that consisted of instrumentation amplifier, multiplexer, micro-controller, filter and transmitter module. The device measures ECG with four electrodes in the body and transmits the signal to receiver connected in PC by digital radio way. The developed algorithm detects the ST level change, and then classifies the ST shape type using the polynomial approximation. The algorithm finds the least squares curve for the data between S wave and T wave in ECG. This curve is used for the classification of the ST shapes. ST type is classified by comparing the slopes between the reference ST type and the least square curve. Through the result from the developed algorithm, we can know when the ST level change occurs and what the ST shape type is. And, the result of analysis is used to make control signal that decides when ECG recording begin and when stop.

In this paper, we describe the hardware configuration for the ambulatory ECG monitoring device and the algorithm for detection of ST pattern change. The ambulatory ECG recording are available for diagnosis of the heart diseases such as myocardial infarction, arrhythmia, etc. It especially is important to detect the transient ECG pattern change caused by the unbalance between the oxygen supply and the oxygen demand in the cardiac muscle that is called myocardial ischemia. This is one of the reasons why the ambulatory ECG monitoring system is necessary. We designed the portable ECG measurement device with the analysis algorithm. The algorithm analyzes the ECG signal and detects the transient ST changes. The detection of QRS complex is accomplished using its the morphological characteristics such as the steep slope and high amplitude. The developed algorithm detects the ST level change, and then classify the ST shape type using the polynomial approximation. The algorithm finds the least squares curve for the data between S wave and T wave in ECG. This curve is used for the classification of the ST shapes. ST type is classified by calculating the difference between the reference ST type and the least square curve. Through the result from the developed algorithm, we can know when the ST level change occurs and what the ST shape type is. The portable ECG device consists of instrumentation amplifier, multiplexer, micro-controller, filter and transmitter module. The designed ECG device measures ECG with four electrodes on the body and transmits the measured ECG signal to the receiver connected in PC by digital radio way. The available range of wireless communication is 70 m in building and 300 m in open ground