• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.471-478
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• 2011

This UGV (Unmanned Ground Vehicle) is not only widely used in various practical applications but is also currently being researched in many disciplines. In particular, obstacle avoidance is considered one of the most important technologies in the navigation of an unmanned vehicle. In this paper, we introduce a simple algorithm for path planning in order to reach a destination while avoiding a polygonal-shaped static obstacle. To effectively avoid such an obstacle, a path planned near the obstacle is much shorter than a path planned far from the obstacle, on the condition that both paths guarantee that the robot will not collide with the obstacle. So, to generate a path near the obstacle, we have developed an algorithm that combines an edge detection method and a limit-cycle navigation method. The edge detection method, based on Hough Transform and IR sensors, finds an obstacle's edge, and the limit-cycle navigation method generates a path that is smooth enough to reach a detected obstacle's edge. And we proposed novel algorithm to solve local minima using the virtual wall in the local vision. Finally, we verify performances of the proposed algorithm through simulations and experiments.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.591-594
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• 2003

In this paper, we propose a method to avoidance obstacle in which we assume that obstacle has an unstable limit cycle in the chaos trajectory surface. In order to avoid the obstacle, we assume that all obstacles in the chaos trajectory surface in which has an unstable limit cycle with Van der Pol equation. In this paper show also that computer simulation results are satisfy to avoid obstacle in the chaos trajectory with Chua's circuit equation of one or multi obstacle has an limit cycle with Van der Pol (VDP) efuation and compare to rate of cover in one robot which have random walk and Chua's equation.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.145-151
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• 2006

In this paper, we propose a novel navigation method combined Nearness Diagram, Limit-Cycle method and the Vector Field Method for avoidance of unexpected obstacles in the dynamic environment. The Limit-Cycle method is used to obstacle avoidance in front of the robot and the Vector Field Method is used to obstacle avoidance in the side of robot. And the Nearness Diagram Navigation is used to obstacle avoidance in the nearness area of the robot. The performance of the proposed method is demonstrate by simulations.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.883-888
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• 2004

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos UAVs meet an obstacle in an Arnold equation, Chua's equation and hyper-chaos equation trajectory the obstacle reflects the UAV( Unmanned Aerial Vehicle).

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.243-246
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• 2003

In this paper, we propose a novel navigation method combined limit-cycle method and the vector field method for avoidance of unexpected obstacles in the dynamic environment. The limit-cycle method is used to obstacle avoidance in front of the robot and the vector field method is used to obstacle avoidance in the side of robot. The proposed method is tested on pioneer 2-DX mobile robot. The simulations and experiments demonstrate in the effectiveness of the proposed method for navigation of a mobile robot in the complicated and dynamic environments.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.11a
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• pp.197-204
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• 2005

In this paper, we propose a method to an obstacle avoidance of chaotic robots that have unstable limit cycles in a chaos trajectory surface in the ubiquitous environment. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. We also show computer simulation results of Chua's equation, Lorenz equation, Hamilton and Hyper-chaos equation trajectories with one or more Van der Pol as an obstacles. We proposed and verified the results of the method to make the embedding chaotic mobile robot to avoid with the chaotic trajectory in any plane.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.6
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• pp.729-736
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• 2003

In this paper, we propose that the chaotic behavior analysis in the mobile robot of embedding some chaotic such as Chua`s equation, Arnold equation with obstacle. In order to analysis of chaotic behavior in the mobile robot, we apply not only qualitative analysis such as time-series, embedding phase plane, but also quantitative analysis such as Lyapunov exponent In the mobile robot with obstacle. We consider that there are two type of obstacle, one is fixed obstacle and the other is VDP obstacle which have an unstable limit cycle. In the VDP obstacles case, we only assume that all obstacles in the chaos trajectory surface in which robot workspace has an unstable limit cycle with Van der Pol equation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.7-10
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• 2004

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos UAVs meet an obstacle in an Arnold equation or Chua's equation trajectory, the obstacle reflects the UAV

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.123-127
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• 2004

In this paper, we propose that the chaotic behavior analysis in the several Arnold chaos mobile robot of embedding some chaotic such as Arnold equation with obstacle. In order to analysis of chaotic behavior in the mobile robot, we apply not only qualitative analysis such as time-series, embedding phase plane, but also quantitative analysis such as Lyapunov exponent in the mobile robot with obstacle. We consider that there are two type of obstacle, one is fixed obstacle and the other is hidden obstacle which have an unstable limit cycle. In the hidden obstacles case, we only assume that all obstacles in the chaos trajectory surface in which robot workspace has an unstable limit cycle with Van der Pol equation.

• Journal of Biosystems Engineering
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• v.3 no.1
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• pp.1-19
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• 1978

Power tiller is a major unit of agricultural machinery being used on farms in Korea. About 180.000 units are introduced by 1977 and the demand for power tiller is continuously increasing as the farm mechanization progress. Major farming operations done by power tiller are the tillage, pumping, spraying, threshing, and hauling by exchanging the corresponding implements. In addition to their use on a relatively mild slope ground at present, it is also expected that many of power tillers could be operated on much inclined land to be developed by upland enlargement programmed. Therefore, research should be undertaken to solve many problems related to an effective untilization of power tillers on slope ground. The major objective of this study was to find out the travelling and tractive characteristics of power tillers being operated on general slope ground.In order to find out the critical travelling velocity and stability limit of slope ground for the side sliding and the dynamic side overturn of the tiller and tiller-trailer system, the mathematical model was developed based on a simplified physical model. The results analyzed through the model may be summarized as follows; (1) In case of no collision with an obstacle on ground, the equation of the dynamic side overturn developed was: $$\sum_n^{i=1}W_ia_s(cos\alpha cos\phi-{\frac {C_1V^2sin\phi}{gRcos\beta})-I_{AB}\frac {v^2}{Rr}}=0$$ In case of collision with an obstacle on ground, the equation was: $$\sum_n^{i=1}W_ia_s\{cos\alpha(1-sin\phi_1)-{\frac {C_1V^2sin\phi}{gRcos\beta}\}-\frac {1}{2}I_{TP} \( {\frac {2kV_2} {d_1+d_2}\)-I_{AB}{\frac{V^2}{Rr}} \( \frac {\pi}{2}-\frac {\pi}{180}\phi_2 \} = 0 $$ (2) As the angle of steering direction was increased, the critical travelling veloc\ulcornerities of side sliding and dynamic side overturn were decreased. (3) The critical travelling velocity was influenced by both the side slope angle .and the direct angle. In case of no collision with an obstacle, the critical velocity $V_c$ was 2.76-4.83m/sec at $\alpha=0^\circ$, $\beta=20^\circ$ ; and in case of collision with an obstacle, the critical velocity $V_{cc}$ was 1.39-1.5m/sec at $\alpha=0^\circ$, $\beta=20^\circ$ (4) In case of no collision with an obstacle, the dynamic side overturn was stimu\ulcornerlated by the carrying load but in case of collision with an obstacle, the danger of the dynamic side overturn was decreased by the carrying load. (5) When the system travels downward with the first set of high speed the limit {)f slope angle of side sliding was $\beta=5^\circ-10^\circ$ and when travels upward with the first set of high speed, the limit of angle of side sliding was $\beta=10^\circ-17.4^\circ$ (6) In case of running downward with the first set of high speed and collision with an obstacle, the limit of slope angle of the dynamic side overturn was = $12^\circ-17^\circ$ and in case of running upward with the first set of high speed and collision <>f upper wheels with an obstacle, the limit of slope angle of dynamic side overturn collision of upper wheels against an obstacle was $\beta=22^\circ-33^\circ$ at $\alpha=0^\circ -17.4^\circ$, respectively. (7) In case of running up and downward with the first set of high speed and no collision with an obstacle, the limit of slope angle of dynamic side overturn was $\beta=30^\circ-35^\circ$ (8) When the power tiller without implement attached travels up and down on the general slope ground with first set of high speed, the limit of slope angle of dynamic side overturn was $\beta=32^\circ-39^\circ$ in case of no collision with an obstacle, and $\beta=11^\circ-22^\circ$ in case of collision with an obstacle, respectively.