• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.971-980
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• 2010

In this paper, we present a navigation control algorithm for mobile robots that move in environments having static and moving obstacles. The algorithm includes a global and a local path-planning algorithm that uses $D^*$ search algorithm, a fuzzy logic for determining the immediate level of danger due to collision, and a fuzzy logic for evaluating the required wheel velocities of the mobile robot. To apply the $D^*$ search algorithm, the two-dimensional space that the robot moves in is decomposed into small rectangular cells. The algorithm is verified by performing simulations using the Python programming language as well as by using the dynamic equations for a two-wheeled mobile robot. The simulation results show that the algorithm can be used to move the robot successfully to reach the goal position, while avoiding moving and unknown static obstacles.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.24-30
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• 2016

The accuracy of small and low-cost CCD cameras is insufficient to provide data for precisely tracking unmanned aerial vehicles (UAVs). This study shows how a quad rotor UAV can hover on a human targeted tracking object by using data from a CCD camera rather than imprecise GPS data. To realize this, quadcopter UAVs need to recognize their position and posture in known environments as well as unknown environments. Moreover, it is necessary for their localization to occur naturally. It is desirable for UAVs to estimate their position by solving uncertainty for quadcopter UAV hovering, as this is one of the most important problems. In this paper, we describe a method for determining the altitude of a quadcopter UAV using image information of a moving object like a walking human. This method combines the observed position from GPS sensors and the estimated position from images captured by a fixed camera to localize a UAV. Using the a priori known path of a quadcopter UAV in the world coordinates and a perspective camera model, we derive the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated quadcopter UAV's altitude. Since the equations are based on the geometric constraint equation, measurement error may exist all the time. The proposed method utilizes the error between the observed and estimated image coordinates to localize the quadcopter UAV. The Kalman filter scheme is applied for this method. Its performance is verified by a computer simulation and experiments.

• Journal of the Korea Society for Simulation
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• v.17 no.2
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• pp.91-103
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• 2008

In order to simulate the behavior of automated manufacturing systems, the performance of material handling systems should be measured dynamically. Multi-Agent technology could be well adapted for the development of simulator for distributed and intelligent manufacture systems. A multi-agent system is composed of one coordination agent and multiple application agents. Issues in AGVS simulator can be classified by the set-up and operating problems. Decisions on the number of vehicles, bi- or uni-directional guide-path, etc. are fallen into the set-up problem category, while deadlock tree algorithm and conflict resolution are in operating problem. In this paper, a multi-agent based deadlock-free simulator for automated guided vehicle system(AGVS) are proposed through the use of multi-agent technologies and the development of deadlock-free algorithm. In this AGVS simulator proposed, well-known Floyd algorithm is used to create AGVS Guide path, through which AGVS move. Also, AGVs avoid vehicle conflict and deadlock using check path algorithm. And Moving vehicle agents are operated in real-time control by coordination agent. AGV position is dynamically calculated based on the concept of rolling time horizon. Simulator receives and presents operating information of vehicle in AGVS Gaunt chart. The performance of the proposed algorithm and developed simulator based on multi-agent are validated through set of experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.236-241
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• 2008

This paper presents a method to recognize the plane regions for movement of walking robots. When the autonomous agencies using stereo camera or laser scanning sensor is under unknown 3D environment, the mobile agency has to detect the plane regions to decide the moving direction and perform the given tasks. In this paper, we propose a very fast method for plane detection using normal vector of a triangle by 3 vertices defined on a small circular region. To reduce the effect of noises and outliers, the triangle rotates with respect to the center position of the circular region and generates a series of triangles with different normal vectors based on different three points on the boundary of the circular region. The vectors for several triangles are normalized and then median direction of the normal vectors is used to test the planarity of the circular region. The method is very fast and we prove the performance of algorithm for real range data obtained from a stereo camera system.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.747-753
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• 2005

In this paper, as an anti-sway control strategy of container cranes, we investigate a variable structure control in which the moving load follows a given trajectory, whereas both the trolley and hoist controllers achieve their positioning problems. It is crucial, in an automated container terminal, that collisions should be avoided during the transference of containers from one place to another. It is also necessary, in the case of a quay crane, to select suitable loading and unloading trajectories of containers, so that possible collisions with surrounding obstacles are avoided. After a brief introduction of the mathematical model, a robust control scheme (i.e., a second-order sliding mode control that guarantees a fast and precise transference and a suppression of the resulted swing) is presented. Despite model uncertainties and unmodeled actuators dynamics, the swing suppression from the given trajectory is obtained by constraining the system motion on suitable sliding surfaces, which include both the desired path and the swing angle. The proposed controller has been tested with a laboratory-size pilot crane. Experimental results are provided.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.319-327
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• 2019

The muscle activity and balance ability of the acute stroke patient has been checked by the functional electrical stimulation using biofeedback fusion postural control training in this study. Functional electrical stimulation using biofeedback fusion postural control training have been implemented on 15 trainees and general biofeedback fusion postural control training have been implemented on another 15 trainees for 30 minutes at 5 times per week during 8 weeks, and vastus lateralis, vastus medialis, rectus femoris and biceps femoris have been measured using the biceps femoris to evaluate the muscle activity of the lower extremity. The moving surface area, whole path length and limited of stability have been measured using biorecue to measure the balance ability. There was statistically meaningful difference on the vastus lateralis, vastus medialis, rectus femoris and biceps femoris in the muscle activity of the lower extremity and there was statistically meaningful difference on surface area, whole path length and limited of stability in the balancing ability. Based on above, it is realized that the functional electrical stimulation using biofeedback fusion postural control training is more effective than the general biofeedback fusion postural control training on the improvement of the muscle activity of the lower extremity and the balance ability.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.5
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• pp.536-542
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• 2000

This paper proposes Visual Script Language which can direct a type of motion to 3D human model and create by dragging gesture like as we can express a certain meaning with hand gestures. Traditional motion control technique of articulated figures such as human needs a complex task that draws on highly developed human skills. So it will reduce the amount of motion specification to provide the motion control method that allow users to describe characters' motion at the higher level abstraction. Visual script is the visual gestures to direct various human motions, so users can express the spatial attributes of a motion such as the path of moving with high-level concepts if they use visual script. And we can show that it is possible to control the motion of human model directly and intuitively by development of 3D human motion control system based on visual script.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.5
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• pp.467-474
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• 2001

When user wants to animate more than one character, some unexpected motion animation like a collision between characters may occur. Therefore, this problem must be resolved using a proper control mechanism. Therefore, this problem must be resolved using a proper control mechanism. This paper proposes an agent-based system that controls the motion animation of the character for representing animation scenario reflecting user\`s intention. This system provides a method that coordinates a type of motion and avoids collision between characters according to the moving path of a character in three-dimensional space. Agent communicates with others for motion synchronization. Agent is extended into several intelligent agents that coordinate character\`s motion. Agent system enables not only an intended motion animation, but also the scheduling of motion to an entire character animation. It designs automata model using Petri-net analysis tool for the agent\`s interaction as a method that passes the agent\`s information and infers the current state of agents. We implement this agent system to control the motion of character using agent technology and show an example of controlling the motion of human character model to prove the possiblity of motion control.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1183-1188
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• 2005

In this paper, we propose a 3D automated measuring system which measures the mandibular movements and the reference plane of the jaw movements. In diagnosis and treatment of the malocclusions, it is necessary to estimate the mandibular movements and the reference plane of the jaw movements. The proposed system is configured with double stereo-cameras, PC, two moving pattern plates(MPPs), two fixed pattern plates(FPPs) and one orbital marker. The virtual pattern plate is applied to calculate the homogeneous transformation matrices which describe the coordinates systems of the FPP and MPP with respect to the world coordinates system. To estimate the parameters of the hinge axis, the Euler's theorem is applied. The hinge axis points are intersections between the FPPs and the hinge axis. The coordinates of a hinge axis point with respect to the MPP coordinates system are set up to fixed value. And then, the paths of the jaw movement can be calculated by applying the homogeneous transformation matrix to fixed hinge axis point. To examine the accuracy of the measurements, experiments of measuring the hinge axis points and floating paths of them are performed using the jaw motion simulator. As results, the measurement errors of the hinge axis points are within reasonable boundary, and the floating paths are very similar to the simulator's moving path.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.428-434
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• 2017

In recent years, owing to the growing user demand for the two-way internet service based on the mobile global broadband communications, a new type of satellite terminal has been developed, known as ESIM(Earth Station in Motion). This service was required by Resolution 158(WRC-15) to study on the coexistence with the co-primary FS(Fixed Service) in 27.5-29.5 GHz as a FSS(Fixed Satellite Service) uplink. In this paper, the average received power on ESIM within -10 dB of beam width of FS and its outage probability was analyzed theoretically and also simulated to account for the azimuth angle with uniform distribution. From the results, it can be concluded that this theoretical analysis is very useful to analyze the interference from ESIM into FS based on the statistical and probabilistic method. Therefore, it is necessary to control the azimuth angle due to a moving terminal as well as the inclination angle of moving path, the operation hours, and the speed of ESIM to protect the co-primary FS.