• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.401-406
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• 2013

The mobile robot is one of the widely-used systems in service industry. We propose a gain-scheduling feedback controller for the tracking control of the mobile robot. The benefit of our proposed controller is that it avoids the singularity issue occurs with the controllers suggested in [4], [10]. Moreover, we show the stability analysis of the controlled system via a Lyapunov stability approach such that the exponential convergence of tracking error to zero is analytically provided. The simulation results show the validity of the proposed controller and improved control performance over the conventional controller.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.27-30
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• 2000

In this paper, we determine the design criteria of haptic device considering the human haptic system and determine the design specifications. We developed a new 2DOF haptic device based on the specifications. It has the wide workspace, statically-balanced, constant inertia matrix, well-conditioned Jacobian matrix and so on. There also is not singularity point within workspace of the device. We show that it has better performance than other 2DOF haptic device in the many aspects.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.379-385
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• 1988

A kinematic control for redundant manipulators is consisdered. An efficient computation method is proposed to determine the joint variable solutions for a given Cartesian path of the end effector. In the proposed method, the Jacobian matrix and its pseudoinverse matrix are calculated intermittently only when the errors exceed the prescribed tolerance. Thereby, the computational burdens are greatly reduced, and at the same time, the errors are maintained within a tolerable range. To show the effectiveness of the mehtod, the result of the simulation is provided in which the redundancy of the manipulator is resolved to avoid the singularity.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.60-68
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• 1998

Parallel link manipulators have an ability of more precise positioning than serial open-loop manipulators. However. general parallel link manipulators have been restricted to the real applications since they have limited workspace due to interference among actuators. In this study, we suggest a closed-loop manipulator with 6 degrees-of-freedom and with enlarged workspace. It consists of two parts for minimizing the interference among actuators. One part is lower structure with planar 3 degrees-of-freedom and the other is upper one with spatial 3 degrees-of-freedom. Forward kinematics and inverse kinematics are solved, research about singularity points are carried out and workspace is evaluated. The comparison of workspace between Stewart platform, which is the typical parallel link manipulator, and the suggested manipulator shows that the workspace of the latter is wider than that of the former. Especially, simulation results also show that the suggested manipulator is more suitable when there needs rotation in the end-effector.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.170-177
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• 1993

In robotic arc welding, the roll (rotation) of the torch about its direction vector does not have any effect on the welding operation. Thus we could use this redundant degree of greedom for the motion control of the robot manipulator. This paper presents an algorithm for the pseudo- inverse kinematic motion control of the 6-axis robot, which utilizes the above mentioned redunancy. The prototype welding operation and the tool path are also graphically simulated. Since the proposed algorithm requires only the position and normal vector of the weldine as an input data, it is useful for the CAD-based off-line programming of the arc welding robot. In addition, it also has the advantages of the redundant manipulator motion control, like singularity avoidance and collision free motion planning, when compared with the other motion control method based on the direct inverse kinematics.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.621-625
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• 2005

This paper presents a new hybrid serial-parallel robot(HSPR), which has six degrees of freedom driven by ball screw linear actuators and motored joints. This hybrid robot design presents a compromise between high rigidity of fully parallel manipulators and extended workspace of serial manipulators. The hybrid robot has a large, singularity-free workspace and high stiffness. Therefore, the presented kinematic structure of the hybrid robot is particularly suitable for multi-tasking machining processes such as milling, drilling, deburring and grinding. In addition to the machining processes, the hybrid robot can be used for welding, fixturing, material handling and so on. The study on design of the hybrid robot is performed. A kinematic analysis and mechanism description of the hybrid robot with six-controlled degree of freedom is presented. In the virtual design works by DADS, workspace and force analysis are discussed. A numerical model is treated to demonstrate our analysis and to determine the range of permissible extension of the struts. Also, we determine some important design parameters for the hybrid robot.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.486-494
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• 2006

In this paper, we present the complete isotropy analysis of a caster wheeled omnidirectional mobile robot (COMR) with nonredundant/redundant actuation. It is desirable for robust motion control to keep a COMR close to the isotropy but away from the singularity as much as possible. First, with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, a general form of the isotropy conditions of a COMR is given in terms of physically meaningful vector quantities which specify the wheel configuration. Third, for all possible nonredundant and redundant actuation sets, the algebraic expressions of the isotropy conditions are derived so as to identify the isotropic configurations of a COMR. Fourth, the number of the isotropic configurations, the isotropic characteristic length, and the optimal initial configuration are discussed.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.615-620
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• 1989

Recently industrial robots are often used together with positioners to enhance the system performance for arc welding. In this paper, the redundancy control method is proposed for the robot-positioner system which is modeled as one kinematic model of 7 degrees of freedom. Also, the manipulability measure based on the Jocobian matrix is utilized to visualize the distribution of manipulability in a given section of the working space. An algorithm for the manipulability maximazation in a given task is developed and applied to the robot and positioner system. The simulation results are given in the case of straight line following.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.953-959
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• 2021

In this paper, the numerical inverse kinematics analysis is presented for a collaborative robot with an offset wrist. Robot manipulators with offset wrist are widely used in industrial applications, due to many advantages over those with wrist center and those with three parallel axes such as simple mechanical design, light weight, and so on. There may not exist a closed-form solution for a robot manipulator with offset wrist. A simple numerical method is applied to solve the inverse kinematics with offset wrist. Singularity is analyzed using Jacobian matrix and the numerical inverse kinematics algorithm is implemented on the real-time controller.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.175-182
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• 2020

The calculation of the optimal trajectory of the stepped top-down robot was made using a genetic algorithm and a computational torque controller. First, the total energy efficiency was minimized using the Red-Cold Generic Algorithm (RCGA) consisting of reproductive, cross, and mutation. The reproducibility condition related to the position assembly of the start and end of the stride and the joints, angles, and angular velocities are linear constraints. Next, the unequal constraint accompanies the condition for preventing the collision of the swing leg at the corner with the outer surface of the stairs, the condition of the knee joint for preventing kinematic peculiarity, and the condition of no moment in safety in the traveling direction. Finally, the angular trajectory of each joint is defined by fourth-order polynomial whose coefficient is to approximate chromosomes. This is to approximate walking. In this study, the energy efficiency of the optimal trajectory was analyzed by computer simulation through a biped robot with seven degrees of freedom composed of seven links.