• Journal of Institute of Control, Robotics and Systems
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• v.13 no.12
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• pp.1207-1212
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• 2007

We propose a haptic interface algorithm for joystick operators working in remote control systems of unmanned vehicles. The haptic interface algorithm is implemented using a force-feedback joystick, which is equipped with low price DC motors without encoders. Generating specific amounts of forces on the joystick pole according to the distance between a remote controlled vehicle and obstacles, the haptic interface enables the operator to perceive the distance information by the sense of touch. For the case of no joystick operation or no obstacles in the working area, we propose an origin control algorithm, which positions the joystick pole at the origin. The origin control algorithm prevents the false movement of the remote vehicles and provides the operator with a realistic force resisting the joystick pole's movement. The experiment results obtained under various scenarios exemplify the validity of the proposed haptic interface algorithm and the origin control algorithm.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.266-268
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• 2005

Recently, the ability of sensing obstacles by oneself and creating suitable moving path in mobile robots are required to provide various kinds automation services. Therefore, in this paper, we studied the avoidance behavior of mobile robots from dynamic obstacles using potential function that minimizes distance and time. We examined the performance of the proposed algorithm by comparing the method of based on the geometrical experience in simulations.

• The Journal of Korea Robotics Society
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• v.3 no.3
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• pp.186-193
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• 2008

We propose a novel real-time obstacle avoidance method for rescue robots. This method, named the ELA(Emergency Level Around), permits the detection of unknown obstacles and avoids collisions while simultaneously steering the mobile robot toward safe position. In the ELA, we consider two sensor modules, PSD(Position Sensitive Detector) infrared sensors taking charge of obstacle detection in short distance and LMS(Laser Measurement System) in long distance respectively. Hence if a robot recognizes an obstacle ahead by PSD infrared sensors first, and judges impossibility to overcome the obstacle based on driving mode decision process, the order of priority is transferred to LMS which collects data of radial distance centered on the robot to avoid the confronted obstacle. After gathering radial information, the ELA algorithm estimates emergency level around a robot and generates a polar histogram based on the emergency level to judge where the optimal free space is. Finally, steering angle is determined to guarantee rotation to randomly direction as well as robot width for safe avoidance. Simulation results from wandering in closed local area which includes various obstacles and different conditions demonstrate the power of the ELA.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.19-25
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• 2013

For safe remote control, information on remote environment has to be delivered to operator realistically, and there have been numerous research efforts on this respect. Among them, haptic technology can significantly enhance safety and overall effectiveness of remote operation by delivering various kinds of information on virtual or real environment to operator. In this study, remote control based on haptic feedback is applied to control of mobile robot moving according to the command from operator avoiding collision with environmental obstacles and maintaining safe distance from them using ultrasonic sensors. Specifically, a remote feedback control structure for mobile robot is proposed. The controller is based on the inner feedback loop that directly utilizes information on distance to obstacles, and the outer feedback loop that the operator directly commands using the haptic device on which the computed reaction force based on the distance information is acting. Effectiveness of the proposed remote control scheme using double feedback loops is verified through a series of experiments on mobile robot.

• PNF and Movement
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• v.8 no.2
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• pp.57-67
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• 2010

Background and Purpose : Many Physical therapist are inclined to communicate less effectively each other because they hardly use the standard terminology. The purposes of this case report are (1) to apply ICF-based documentation in evaluation (2) to submit the strategy of intervention process to improve the ability of walking short distance of the client who has post-stroke. Description : The client was 44-years-old man with hemiplegia who was in 1 month post-stroke problems were diagnosed while applying the ICF core set. The goals agreed with client were independently walking short distance, stairs and obstacles. To come up with the intervention strategy, hypothesis was set and 4 weeks of intervention was carried out after proposing the short goal and detailed purpose. Outcome : The client's performance in walking short distance and confidence were increased after impairment focused intervention, that are improved in walking velocity, endurance, supporting ability in lower limbs, rhythmical movement in upper limbs and the coordination of both limbs. Activities focused intervention also enhanced the ability in climbing steps and walking around obstacles. Conclusion : The decided hypothesis and goal that are to solve the problems the client faced were remarkably meaningful.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.4
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• pp.469-478
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• 2012

This study aims to discover the optimal pipe layout for a ship, which generally needs a lot of time, efforts and experiences. Genetic algorithm was utilized to search for the optimum. Here the optimum stands for the minimum pipe length between two given points. Genetic algorithm is applied to planar pipe layout problems to confirm plausible and efficiency. Sub-programs are written to find optimal layout for the problems. Obstacles are laid in between the starting point and the terminal point. Pipe is supposed to bypass those obstacles. Optimal layout between the specified two points can be found using the genetic algorithm. Each route was searched for three case models in two-dimensional plane. In consequence of this, it discovered the optimum route with the minimized distance in three case models. Through this study, it is possible to apply optimization of ship pipe route to an actual ship using genetic algorithm.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.11-17
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• 2008

Falls associated with tripping over an obstacle can be dangerous, yet little is known about the strategies used for stepping over obstacles by Parkinson's patients. The purpose of this study was to investigate stepping over gait characteristics according to obstacle height in Parkinson's patients. The gait of 7 Parkinson's patients was examined during a 5.0 m approach to, and while stepping over, obstacles of 0, 2.5, 5.2, and 15.2 cm. Only five Parkinson's patients were able to clear all obstacles successfully; as such, only their data were analyzed. A one-way ANOVA for repeated measures was employed for selected kinematic variables to analyze the differences of the height of four obstacles. The results showed significant differences between obstacle height and: approaching speed (AS), foot clearance from the obstacle(FC), and step width (SW). The results showed no significant differences between obstacle height and: crossing speed (CS), toe distance (TD), and heel distance (HD). This strategy tends to reduce the risk of toe contact with the obstacle. Parkinson's patients were stepping over the obstacle slowly, stably and inefficiently.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.113-123
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• 2000

In the navigation for a mobile robot, the collision avoidance with unexpected obstacles is essential for the safe navigation and it is independent of the technique used to control the mobile robot. This paper presents a new collision avoidance algorithm using neural network for the safe navigation of the autonomous mobile robot equipped with CAN and ultrasonic sensors. A tracked wheeled mobile robot has a stability and an efficiency to move on a rough ground. And its mechanism is simple. However it has difficulties to recognize its surroundings. Because the shape of the tracked wheeled mobile robot is a square type, sensor modules are generally located on the each plane surface of 4 sides only. In this paper, the algorithm using neural network is proposed in order to avoid unexpected obstacles. The important character of the proposed algorithm is to be able to detect the distance and the angle of inclination of obstacles. Only using datum of the distance and the angle, informations about the location and shape of obstacles are obtained, and then the driving direction is changed. Consequently, this algorithm is capable of real time processing and available for a mobile robot which has few sensor modules or the limited sensing range such as a tracked wheeled mobile robot. Effectiveness of the proposed algorithm is illustrated through a computer simulation and an experiment using a real robot.

• Journal of Korea Planning Association
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• v.53 no.7
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• pp.39-48
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• 2018

The purpose of this study is to verify the stable flight conditions of drones within a limited urban area by using the ICAO(International Civil Aviation Organization) reich model which is using to evaluate civil aircraft stability. The results of the study are summarized as follows. First, in order for the drones flying stably, the horizontal safety separation distance between a drone and another should be at least 1,852M. Second, assuming that no obstacles within 1,852M of horizontal space, two drones can be fly into upper and lower spaces. However there are obstacles such as buildings, it is impossible to secure a 1,852M distance between drones. Third, sensitivity analysis point out that the separation interval($s_x$) of drone aviation has the greatest influence on the TLS(Target Level of Safety). If future research is conducted to lower the numerical values, the safety distance between a drone and another drone will be drastically reduced, allowing more detailed urban space division, and will be presented as a scientific numerical value for establishing a dedicated path for the drones.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.475-475
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• 2000

This paper describes the construction of an autonomous mobile robot with functions of collision avoidance and speech recognition that is used for teaching path of the robot. The human voice as a teaching method provides more convenient user-interface to mobile robot. For safe navigation, the autonomous mobile robot needs abilities to recognize surrounding environment and avoid collision. We use u1trasonic sensors to obtain the distance from the mobile robot to the various obstacles. By navigation algorithm, the robot forecasts the possibility of collision with obstacles and modifies a path if it detects dangerous obstacles. For these functions, the robot system is composed of four separated control modules, which are a speech recognition module, a servo motor control module, an ultrasonic sensor module, and a main control module. These modules are integrated by CAN(controller area network) in order to provide real-time communication.