• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1448-1456
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• 1999

In this paper, we propose a new technique for path-following of the wheeled mobile robot systems with nonholonomic constraints using a path-observer. We discuss the path-following problems of the nonholonomic mobile robot systems which have two nonsteerable, independently driven wheels with the various initial conditions such as a position, a heading angle, and a velocity. It is shown that the performance of dynamic path-following importantly is affected by the intial conditions. Particularly, if the initial conditions become more distant from the desired path and the desired velocity become faster, the system is shown to have worse performance and small time local stable. To find the controllable and stable control for path-following with various initial configuration, we propose the path-observer which can be used for control of the stable path-following of nonholonomic mobile robot system with the various initial conditions. The proposed scheme exhibits the efficient path-following properties for nonholonomic mobile robot in any intial conditions. The simulation results demonstrate the effectiveness of the proposed method for dynamic path-following tasks with the various initial conditions.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.1
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• pp.33-40
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• 2000

In this paper, an integrated method for the path planning and motion control of wheeled mobile robots using a hybrid system model and control is presented. The hybrid model including the continuous dynamics and discrete dynamics with the continuous and discrete state vector is derived for a two wheel driven mobile robot. The architecture of the hybrid control system for real time path planning and following is designed which has the 3-layered hierarchical structure : the discrete event system using the digital automata as the higher process, the continuous state system for the wheel velocity controls as the lower process, and the interface system as the interaction process between the continuous system as the low level and the discrete event system as the high level. The reference motion commands for autonomous navigation are generated by the abstracted motion in the discrete event system. The motion control tasks including the feasible path planning and autonomous motion control with various initial conditions are investigated as the applications by the simulation studies.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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• pp.1238-1243
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• 2008

This paper presents an HILS(Hardware in the Loop Simulations) based experimental study for the UAV's flight trajectory planning/generation algorithms and guidance/control laws. For the various mission that is loaded on each waypoint, proper trajectory planning and generation algorithms are applied to achieve best performances. Specially, the 'smoothing path' generation and the 'tangent orbit path' guidance laws are presented for the smooth path transitions and in-circle loitering mission, respectively. For the control laws that can minimize the effects of side wind, side slip angle($\beta$) feedback to the rudder scheme is implemented. Finally, being implemented on real hardwares, all the proposed algorithms are validated with integrations of hardware and software altogether via HILS.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.786-794
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• 1998

This paper proposes an automatic microshaping technology using laser and applies it to implementation of semicutting control system of the panel inside which a car air bag is equipped. Since it is impossible to project laser directly onto the desired working point of a target panel due to fixedness of laser generator, we reflect the generated laser, using reflection mirrors and focusing lenses, to project onto the desired working point. Also, in order to conduct an uniform semicutting control with constant width and depth, we control the end-effector of manipulator, which grasp the laser reflection mirror, to track working path with constant speed and orientation. The validity and effectiveness of the proposed methods are checked through experiments tracking a path formatted with straight lines and arcs.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.7
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• pp.1005-1014
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• 1990

This paper proposes the control unit of a 32-bit high-performance RISC type microprocessor. This control unit controls the whole data path of target processor and on chip instruction/data caches in 4-stage pipelined scheme. For the improvement of speed, large parts of data path and control unit are designed by domino-CMOS and hard-wired circuit technology. First, in this paper, target processor's instruction set and data path are defined, and next, all signals needed to control the data path are analyzed. The decoder of control unit and clock generated logic block are implemented in DCAL(Dynamic CMOS Array Logic) with modified clock scheme for the purpose of speed up and supporting RISC processor's pipelined architecture efficiently.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.12
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• pp.1601-1609
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• 1988

In the control of the robotic manipulators, the variable structure control method for the set point Regualation has an advantage of the insensitivity about parameter variations and disturbances. When the robotic manipulatores are controlled by a point-to-point scheme, no path constraint is considered. Thus, the variable structure control method will be effectively applied only if the trajectory of the robot hand is estimated precisely. In this paper, the joint trajectories in the joint space and the hand trajectory in the cartesian space are calculated by the variable structure control method, and an algorithm is suggested to elaborate the deviation error of the robot hand from a straight line path. The result of this study will become a base of the effective path planning about robotic manipulators with the variable structure control concept.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.710-715
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• 1990

This paper presents a path control method for mobile robot using neural network and a systematic method for the kinematic and dynamic modelling of a mobile robot. The robot finds its path deviation by taking the signals of an optical array sensor and determined its moving behaviors using neural net control method. A robot can be taught behaviors by changing the given patterns, in this work, Back Propagation rule is used as a learning method.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.771-779
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• 2010

This paper presents a method that integrates the geometric path tracking and the obstacle avoidance for nonholonomic mobile robot. The mobile robot follows the path by moving through the turning radius given from the pure pursuit method which is the one of the geometric path tracking methods. And the obstacle generates the obstacle potential, from this potential, the virtual force is obtained. Therefore, the turning radius for avoiding the obstacle is calculated by proportional to the virtual force. By integrating the turning radius for avoiding the obstacle and the turning radius for following the path, the mobile robot follows the path and avoids the obstacle simultaneously. The effectiveness of the proposed method is verified through the real experiments for path tracking only, static obstacle avoidance, dynamic obstacle avoidance.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.4
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• pp.392-398
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• 2008

We propose a new path planning method for autonomous mobile robots. To maximize the utility of mobile robots, the collision-free shortest path should be generated by on-line computation. In this paper, we develop an effective and practical method to generate a good solution by lower computation time. The initial path is obtained from skeleton graph by Dijkstra's algorithm. Then the path is improved by changing the graph and path dynamically. We apply the dynamic programming algorithm into the stage of improvement. Simulation results are presented to verify the performance of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.5
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• pp.444-449
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• 2006

Path planning is a key element in navigation of a mobile robot. Several algorithms such as a gradient method have been successfully implemented so for. Although the gradient method can provide the global optimal path, it computes the navigation function over the whole environment at all times, which result in high computational cost. This paper proposes a high-speed path planning scheme, called a gradient method with topological information, in which the search space for computation of a navigation function can be remarkably reduced by exploiting the characteristics of the topological information reflecting the topology of the navigation path. The computing time of the gradient method with topological information can therefore be significantly decreased without losing the global optimality. This reduced path update period allows the mobile robot to find a collision-free path even in the dynamic environment.