• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.69-72
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• 1996

This paper considers a global resolution of kinematic redundancy under inequality constraints as a constrained optimal control. In this formulation, joint limits and obstacles are regarded as state variable inequality constraints, and joint velocity limits as control variable inequality constraints. Necessary and sufficient conditions are derived by using Pontryagin's minimum principle and penalty function method. These conditions leads to a two-point boundary-value problem (TPBVP) with natural, periodic and inequality boundary conditions. In order to solve the TPBVP and to find a global minimum, a numerical algorithm, named two-stage algorithm, is presented. Given initial joint pose, the first stage finds the optimal joint trajectory and its corresponding minimum performance cost. The second stage searches for the optimal initial joint pose with globally minimum cost in the self-motion manifold. The effectiveness of the proposed algorithm is demonstrated through a simulation with a 3-dof planar redundant manipulator.

• 한국CDE학회논문집
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• 제10권4호
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• pp.284-292
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• 2005

This paper presents a new framework of kinematic tolerance synthesis and describes the implemented algorithm for planar mechanical systems comprised of higher kinematic pairs. Input to the synthesis algorithm is a parametric model of the mechanical system with allowed parameter ranges (tolerance ranges). The model is specified as the part profiles consisting of line and arc segments and the motion axes along which each part moves. The algorithm analyzes tolerance in generalized configuration space, called contact zones bounding the worst-case variations, and identifies bad system variations. The bad system variations then are removed out of the parameter ranges by adjusting the nominal parameter values if possible and then shrinking the ranges otherwise. This cycle is repeated until no more bad variations we found. I show the effectiveness of the algorithm by case studies on several mechanisms.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.144-147
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• 2003

In order to evaluate spring-back behavior in automotive sheet forming processes, a panel shape idealized as a SS-rail has been investigated. After spring-back kas been predicted fer SS-rails using the finite element analysis, results has been compared with experimental measurements for three automotive sheets. To account for hardening behavior such as the Bauschinger and transient effects in addition to anisotropic behavior, the combined isotropic-kinematic hardening law based on the Chaboche type single-surface model and a recently developed non-quadratic anisotropic yield function have been utilized, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.213-216
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• 1996

This paper studies a class of in-parallel manipulators with special geometry where the forward displacement analysis problem can be solved easier than the fully parallel manipulators. Three horizontal links of this mechanism provide 3DOFs(Degrees of Freedom), which are one degree of orientational freedom and two degrees of translatory freedom. Three vertical links of this mechanism provide 3DOFs, which are two degrees of orientational freedom and one degree of translatory freedom. The main advantages of this manipulator, compared with the Stewart platform type, are the capability to produce pure rotation and to predict the motion of the moving platform easily. Since this manipulator has simple kinematic characteristics compared with the Stewart platform, controlling in real-time is possible due to less computational burden. The purpose of this investigation is to develope an analytical method and systematic method to analyze the basic kinematics of the manipulator. The basic kinematic equations of the manipulator are derived and simulation is carried out to show the performance of the mechanism.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2154-2159
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• 2005

This paper presents the kinematic analysis of two robots, an exoskeleton type master robot and a human like slave robot with two arms. Two robots are designed and built to be equivalent as motion following robots. The operator wears the exoskeleton robot to generate motions, then the slave robot is required to follow after the motion of the master robot. However, different kinematic configuration yields position mismatches of the end-effectors. To synchronize motions of two robots, kinematic analysis of mapping is analyzed. The forward and inverse kinematics have been simulated and the corresponding experiments are also conducted to confirm the proposed mapping analysis.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.5-8
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• 1999

The main stream of researches on the mobile robot is planning motions of the mobile robot under nonholonomic constraints while only considering kinematic model of a mobile robot. These researches, however, assume that there is some kind of dynamic controller which can produce perfectly the same velocity that is necessary for the kinematic controller. Moreover, there are little results about the problem of integrating the nonholonomic kinematic controller and the dynamic controller for a mobile robot. Also the literature on the robustness of the controller in the presence of uncertainties or external disturbances in the dynamical model of a mobile robot is very few. Thus, in this paper, the robust adaptive controller which can achieve velocity tracking while considering not only kinematic model but also dynamic model of the mobile robot is proposed. The stability of the dynamic system will be shown through the Lyapunov method.

• 전자공학회논문지B
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• 제33B권7호
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• pp.40-50
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• 1996

An unified compliant control algorithm to regulate the force by dual arms is proposed, where tow arms are treated as one arm in a kinematic viewpoint. The force error calculated form the information of two force/torque sensors attached to the end of each arm is transferred to minimum actuator coordinates, and then is distributed to total system actuator coordinates. The position adjustment at the total actuator coordinates is computed based on the effective computed based on the effective compliance matrix with respect to total actuator coordinates, which is obtained by coordinate transformation between the task coordinates and the total actuator coordinates. An experiment is carried out for dual arms with asymmetric kinematic structure to control an interaction force between manipulators and the environment. The performances of the proposed control algorithm are experimentally compared to those of dual arms employing master/slave scheme. The proposed compliant control algorithm not only ouperforms other algorithms, but also can be treated as an unified approach n the sense that it can be applied to arbitrary dual arm systems with general kinematic structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.679-684
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• 1989

In this paper, we describe the PTP notion of robot manipulators by neural networks. The PTP motion requires the inverse kinematic redline and the joint trajectory generation algorithm. We use the multi-layered Perceptron neural networks and the Error Back Propagation(EBP) learning rule for inverse kinematic problems. Varying the number of hidden layers and the neurons of each hidden layer, we investigate the performance of the neural networks. Increasing the number of learning sweeps, we also discuss the performance of the neural networks. We propose a method for solving the inverse kinematic problems by adding the error compensation neural networks(ECNN). And, we implement the neural networks proposed by Grossberg et al. for automatic trajectory generation and discuss the problems in detail. Applying the neural networks to the current trajectory generation problems, we can refute the computation time for trajectory generation.

• 제어로봇시스템학회논문지
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• 제17권12호
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• pp.1256-1265
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• 2011

Automated parking assist systems are being commercialized and rapidly spread in the market. In order to improve odometry accuracy, we proposed a practical odometry calibration scheme of Car-Like Mobile Robot (CLMR). However, there were some open problems in our prior work. For example, it was not clear whether the kinematic parameters always converged or not using the proposed calibration scheme. In addition, test driving had to be carried out "twice" without detailed explanation. This research aims to provide answers for the addressed questions though the convergence property analysis of the calibration scheme. In this paper, we evaluate on the effect of the kinematic parameter error on the odometry error at the final pose by numerical computation. The evaluation will show that the wheel diameter and tread of the CLMR can be calibrated by iterative test drives. In addition, the region of convergence in the parametric space will be discussed. Presented experimental results clearly showed that the proposed calibration scheme would be useful in practical applications.

• 제어로봇시스템학회논문지
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• 제7권9호
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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.