• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.4
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• pp.201-204
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• 2004

In this paper, a direct adaptive tracking controller based Lyapunov method is designed for a wheeled mobile robots. A wheeled mobile robots have three degrees of freedom and two control variables. Therefore, it is difficult to control a mobile robot using the general linear control. We introduce two kinds of Lyapunov function for the design of the controller and verify the controller. A mobile robots using the designed adaptive direct tracking controller is well-behaved and is easily implemented.

• International Journal of Control, Automation, and Systems
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• v.1 no.3
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• pp.376-384
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• 2003

In this paper, the simple geometric kinematics of a three-wheeled holonomic mobile robot is proposed. Wheel architecture is developed for the holonomic mobile platform in order to provide omni-directional motions by three individually driven and steered wheels. Three types of basic motions are proposed for the path generation of the developed mobile robot. All paths of the mobile robot can be achieved through a combination of the proposed basic motion trajectories. The proposed method is verified through computer simulations and the developed mobile robot.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1235-1240
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• 2006

Previous isotropy analysis of a caster wheeled omnidirectional mobile robot(COMR) has been made under the assumption that the steering link offset is equal to the caster wheel radius. Nevertheless, many practical COMR's in use take advantage of the steering link offset different from the wheel radius, mainly because of improved stability. This paper presents the isotropy analysis of a fully actuated COMR with variable steering link offset, which can be considered as the generalization of the previous analysis. First, the kinematic model of a COMR under full actuation is obtained based on the orthogonal decomposition of the wheel velocities. Second, the necessary and sufficient conditions for the isotropy of a COMR are derived and examined to categorize three different groups, each of which can be dealt with in a similar way. Third, for each group, the isotropy conditions are further explored so as to identify all possible isotropic configurations completely.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.212-220
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• 2007

This paper proposes a method of avoiding obstacles and tracking a moving object continuously and simultaneously by using new concepts of virtual tow point and fuzzy danger factor for differential wheeled mobile robots. Since differential wheeled mobile robot has smaller degree of freedom to control and are non-holonomic systems, there exist multiple solutions (trajectories) to control and reach a target position. The paper proposes 'fuzzy danger factor' for obstacles avoidance, 'virtual tow point' to solve non-holonomic object tracking control problem for unique solution and three kinds of fuzzy logic controller. The fuzzy logic controller is policy decision controller with fuzzy danger factor to decide which controller's result is more valuable when the mobile robot is tracking a moving object with obstacles to be avoided.

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.35-42
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• 2003

This paper proposes a simple, robust, nonlinear controller based on Lyapunov stability for tracking the reference welding path and velocity of a two-wheeled welding mobile robot (WMR). The system has three degrees of freedom including two wheels and one torch slider. Torch slider motion is used for faster tracking because the welding speed is very slow. Control law is obtained from the Lyapunov control function to ensure the asymptotical stability of the system. The controller has three free parameters for adjusting the performance of the controlled system. A simple way of measuring the errors using two potentiometers is introduced. The effectiveness of the proposed controller is shown through simulation results.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.501-507
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• 2013

This paper presents the development and balancing control of GYROBO, a one wheeled mobile robot system. GYROBO is a disc type one wheel mobile robot that has three actuators, a drive motor, a spin motor, and a tilt motor. The dynamics and kinematics of GYROBO are analyzed, and simulation studies conducted. A one-wheeled robot, GYROBO is built and its balancing control is performed. Experimental studies of GYROBO's balancing abilities are conducted to demonstrate the gyroscopic effects generated by the spin and tilt angles of a flywheel.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2066-2071
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• 2003

In this paper, we identify the isotropic configurations of an omnidirectional mobile robot with three caster wheels, depending on the selection of actuated joints. First, We obtain the kinematic model of a caster wheeled omnidirectional mobile robot(COMR) without matrix inversion. For a given task velocity, the instantaneous motion of each wheel is decomposed into two orthogonal instantaneous motions of the steering and the rotating joints. Second, with the characteristic length introduced, we derive the isotropy conditions of a COMR having $n({\ge}3)$ actuated joints, which are imposed on two Jacobian matrices, $A{\in}R^{n{\times}3}$ and $B{\in}R^{6{\times}6}$. Under the condition of $B{\propto}I_6$, three caster wheels should have identical structure with the length of the steering link equal to the radius of the wheel. Third, depending on the selection of actuated joints, we derive the conditions for $A^t$ $A{\propto}I_3$ and identify the isotropic configurations of a COMR. All possible actuation sets with different number of actuated joints and different combination of rotating and steering joins are considered.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.191-196
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• 2003

This paper presents a method to design an adaptive controller for the kinematic model of a two-wheeled welding mobile robot (WMR) with unknown parameters. We propose a nonlinear controller based on the Lyapunov function to enhance the tracking properties of the WMR. The WMR can track any smooth curved welding path at a constant velocity of the welding point. The system has three degrees of freedom including two wheels and one torch slider. Torch slider motion is used for fast tracking. To design the tracking performance, the errors from WMR to steel wall is defined, and the controller is designed to drive the errors to zero as fast as possible. The effectiveness of the proposed controller is shown through simulation results.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.766-773
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• 2001

Omni-directional mobile robots have been popularly employed in several application areas. However, the kinematics for these systems have not been clearly identified, specially for redundantly actuated case which is common in omni-directional mobile robot such as the Nomadic model. For such mobile robot systems, exploitation of redundant actuation as well as singularity analysis has not been extensively addressed. In light of this fact, this paper introduces two different kinematic approaches for omni-directional mobile robots. Then, a singular-free load distribution scheme for redundantly actuated three-wheeled omni-directional mobile robot is proposed. Through simulation, several advantages of redundantly actuated mobile robot in aspect of singularity avoidance, minimization of torque norm, and exploiting several subtasks are presented.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.190-199
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• 1993

In this study a three-axes mobile robot which has two independently controlled driving wheels and a function of simultaneously steering the driving wheels has been developed. Two-motion modes of the mobile robot, the first is a differential velocity motion of two driving wheels and the second is a equal driving and steering motion, have been analyzed and the kinematic and dymanic analyses about the each motion mode have been carried out. As a result of dynamic analysis, the torque used on a motor control and acceleration have been derived explicitly. Hence, a computation time is saved effectively and a real time control of the mobile robot considering the dynamics has become possible. Through a simulation the results considering the dynamics have been compared with that no regarding the dynamics and the possibility of real-time control has been proved.