• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.5
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• pp.182-189
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• 2002

This paper presents a framework of hybrid dynamic control systems for the motion control of wheeled mobile robot systems with nonholonomic constraints. The hybrid control system has the 3-layered hierarchical structure: digital automata for the higher process, mobile robot system for the lower process, and the interface as the interaction process between the continuous dynamics and the discrete dynamics. In the hybrid control architecture of mobile robot, the continuous dynamics of mobile robots are modeled by the switched systems. The abstract model and digital automata for the motion control are developed. In high level, the discrete states are defined by using the sensor-based search windows and the reference motions of a mobile robot in low level are specified in the abstracted motions. The mobile robots can perform both the motion planning and autonomous maneuvering with obstacle avoidance in indoor navigation problem. Simulation and experimental results show that hybrid system approach is an effective method for the autonomous maneuvering in indoor environments

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.79-82
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• 1997

In this paper, group intelligence "arrangement" bahavior of autonomous mobile robots(AMRs) is realized by the fuzzy rules. The fuzzy rules for the arrangement are generated from clustering the input-output data. Simulation shows that a small-number of fuzzy rules successfully realizes the arrangement behavior of AMRs.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.4
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• pp.449-455
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• 2014

This paper presents a method for developing a TM (Traversability Map) from a DTM (Digital Terrain Model) collected by remote sensors of autonomous mobile robots. Such a map can be used to plan traversable paths and estimate navigation speed quantitatively in real time for robots capable of performing autonomous tasks over rough terrain environments. The proposed method consists of three parts: a DTM partition module which divides the DTM into equally spaced patches, a terrain information module which extracts the slope and roughness of the partitioned patches using the curve fitting and the fractal-based triangular prism method, and a traversability analysis module which assesses traversability incorporating with extracted terrain information and fuzzy inference to construct a TM. The potential of the proposed method is validated via simulation works over a set of fractal DTMs.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3105-3107
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• 1999

In this paper, we propose a new approach to autonomous wall-following of wheeled mobile robots using hybrid control system. The hybrid control approach IS introduced to the motion control of nonholonomic mobile robots in the Indoor navigation problems. In hybrid control architecture, the discrete states are defined by the user-defined constraints, and the reference motion commands are specified In the abstracted motions. The hybrid control system applied to motion planning and autonomous navigation with obstacle avoidance In indoor navigation problem. Simulation results show that it is an effective method for the autonomous navigation in indoor environments.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.297-305
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• 1999

Autonomous mobile robots are required to achieve multiple goals while responding quickly to the dynamic environments. An appropriate robot control architecture, which clearly and systematically defines the relationship among the inputs, the processing functions and the outputs, thus needs to be embedded in the robot controller. This paper proposes a kind of hybrid control architecture which combines the key features of the two well-known robot control architectures; hierarchical and behavioral- based. The overall control architecture consists of three layers, i.e. the highest planner, the middle plan executor, and the lowest monitor and behavior-based controller. In the planned situation, only one behavior module is chosen by the logical coordinator in the plan executor according to the way point bin. In the exceptional situation, the central controller in the plan executor issues an additional control command to reach the planned way point. Several simulations and experiments with autonomous mobile robot show that the proposed architecture enables the robot controller to achieve the multiple sequential goals even in dynamic and uncertain environments.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2464-2466
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• 2001

In this paper, a behavior-based fuzzy control of mobile robots for autonomous navigation is presented. Behaviors of mobile robots are divided into two categories: reactive behavior and purposeful behavior, which are incompatible with each other. The former is reaction performed in terms of the sensory data and the latter is action for achieving the goal. The presented method generates appropriate control inputs to the robot to trade-off between the reactive and purposeful behaviors using fuzzy inferences. The method is applied to an synchro-drive type mobile robot and shown to be useful for autonomous robot navigation by providing simulation results.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.3
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• pp.275-284
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• 2006

This paper deals with problems of safe and efficient navigation algorithm for autonomous mobile robots in unknown environments. Since the obstacle avoidance algorithms are very important in mobile robot navigation, two obstacle avoidance algorithms: VFH(vector field histogram) algorithm and a fuzzy algorithm are combined to have optimal performance in various environments. And a upper-level supervisor is to select the proper one from VFH algorithm and the fuzzy algorithm according to the situations the robot faces. Computer simulation results show the effectiveness of the proposed navigation algorithm for autonomous mobile robots.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.389-397
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• 2011

The global dynamic window approach (DWA) is widely used to generate the shortest path of mobile robots considering obstacles and kinematic constraints. However, the dynamic constraints of robots should be considered to generate the minimum-time path. We propose a modified global DWA considering the dynamic constraints of robots. The reference path is generated using A* algorithm and smoothed by cardinal spline function. The trajectory is then generated to follows the reference path in the minimum time considering the robot dynamics. Finally, the local path is generated using the dynamic window which includes additional terms of speed and orientation. Simulation and experimental results are presented to verify the performance of the proposed method.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.2
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• pp.14-20
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• 1999

In this paper, we discuss about implementation of a wireless communication system for a distributed autonomous robotic system. In order to achieve cooperative behavior among mobile robots, it is required to perform communication. Based on this requirements, we examined to the application in a wireless communication system used by mobile robots. This paper describes a conceptual and experimental framework which provides a distributed control architecture for the study of interactions between multiple mobile robots.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.803-808
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• 2010

We propose a smooth path planning method for autonomous mobile robots. Due to nonholonomic constraints by obstacle avoidance, the smooth path planning is a complicated one. We generate smooth path that is considered orientation of robot under nonholonomic constraints. The proposed smooth planning method consists of two steps. Firstly, the initial path composed of straight lines is obtained from V-graph by Dijkstra's algorithm. Then the initial path is transformed by changing the curve. We apply the cardinal spline into the stage of curve generation. Simulation results show a performance of proposed smooth path planning method.