• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.811-814
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• 1997

In this paper, the torque optimization of a kinematically redundant manipulator for minimizing the torque demands is discussed. The minimum torque solution based on a local optimization has been known to encounter the instability problem and then the global torque optimization was suggested as one of the alternatives. Herein, by adopting the infinity-norm rather than the 2-norm for the magnitude of torques, we are to propose a new cost function more advantageous to the avoidance of torque limits. By the way, a solution to the global torque optimization formulated with the new cost function can not be obtained by the previous methods due to their difficulties such as inability to treat discontinuous cost functions and various constraints on the joint variables. Thus, to overcome those deficiencies, we are developing a new approach using the dynamic programming. The effectiveness of the proposed method is shown through simulation examples for a 3-link planar redundant manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.756-759
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• 1997

Multi-arm cooperation robot system is required for more specific and dextrous jobs such as transferring very large or heavy objects, or grasping work piece while processing on it. There is little research on 3-dimensional multi-arm robot. Here we propose two performance indices presenting isotropy of end-effector's acceleration and velocity capabilities with constraints of joint torques, that is Isotropic Acceleration Radius [IAR] and Isotropic Velocity Radius [IVRI. Also the procedure to find 3-dimensional IAR, IVR is proposed, where available acceleration set concept is used. The case of 3-dimensional two 3 joint robot system was simulated and the distributions of IAR, IVR was studied.

• 제어로봇시스템학회논문지
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• 제21권12호
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• pp.1160-1166
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• 2015

This paper proposes a decentralized robust adaptive control scheme for robot manipulators with input torque saturation in the presence of uncertainties. The control system should consider the practical problems that the controller gain coefficients of each joint may be nonlinear time-varying and the input torques applied at each joint are saturated. The proposed robot controller overcomes the various uncertainties and the input saturation problem. The proposed controller is comparatively simple and has no robot model parameters. The proposed controller is adjusted by the adaptation laws and the stability of the control system is guaranteed by the Lyapunov function analysis. Simulation results show the validity and robustness of the proposed control scheme.

• 제어로봇시스템학회논문지
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• 제15권6호
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• pp.612-618
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• 2009

This study is concerned about the optimal design of the arm 1 and arm 2 in the SCARA robot. The mass and inertia moment of the arm I and arm 2 in a SCARA robot is greatly affected on the performance such as a cycle time, and torques loaded on $1^{st}$ axis and $2^{nd}$ axis. To reduce the mass and inertia moment, this study carried out optimal design by FEM analysis using parametric variables, which is a width, a height of the rib and a thickness of arm in the arm. The rib is adapted instead of reducing the thickness in the arm. And the simulation by computer was conducted on two given paths in X direction and Y direction. After optimal design, the result showed that maximum torque of $1^{st}$ axis and $2^{nd}$ axis reduced to maximum 9.5% on a given path.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2705-2708
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• 2003

In this paper, we propose a method that applies matrix decomposition technique to the connection of actuator capabilities of each robot to object acceleration limits for multiple cooperative robot systems. The robot systems under consideration are composed of several robot manipulators and each robot contacts a single object to carry the object while satisfying the constraints described in kinematics as well as dynamics. By manipulating kinematic and dynamic equations of both robots and objects, we at first derive a matrix relating joint torques with object acceleration, manipulate the null space of the matrix, and then we decompose the matrix into three parts representing indeterminancy, connectivity, and redundancy. With the decomposed matrix we derive the boundaries of object accelerations from given joint actuators. To show the validity of the proposed method some examples are given in which the results can be expected by intuitive observation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2721-2724
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• 2003

This paper deals with a manipulability analysis of multi-legged walking robots in acceleration domain, that is the dynamic manipulability analysis of walking robot. Noting that the kinematic structure of the walking robot is basically the same with that of the multiple serial robot system holding one object, the analysis method for cooperating robot is converted to that of walking robot. With the proposed method, the bound of achievable acceleration of the moving body is easily derived from the given bounds on the capabilities of Joint torques. Several walking robot examples are analyzed with proposed method under the assumption of hard contact, and presented in the paper to validate the method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2725-2728
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• 2003

The manipulability of robot provides useful Information for the design and path planning of robots. This paper shows an influence of joint velocities to acceleration of robot end-effector using a dynamic manipulability polytope. The main idea of this paper is that the dynamic manipulability polytope of robot can be divided to three intermediate polytope, the torque-dependant polytope, velocity-dependent polytope, and gravity-dependant polytope. The velocity-dependant polytope is made from the limits of robot joint velocities while the torque-dependant polytope is made from the limits of the joint torques. Combining of these two intermediate polytopes and considering the gravity-dependant polytope, the overall dynamic manipulability polytope of robot is obtained. This investigation will be useful on the field of space robot and high-speed application.

• Journal of Magnetics
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• 제21권3호
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• pp.356-363
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• 2016

To improve the sensing accuracy of the newly developed magnetically suspended sensitive gyroscope (MSSG), it is necessary to analyze the causes of drift error. This paper build the models of disturbing torques generated by stator assembly errors based on the geometric construction of the MSSG with double spherical envelope surfaces, and further reveals the generation mechanism of the drift error. Then the drift error from a single stator magnetic pole is calculated quantitatively with the established model, and the key factors producing the drift error are further discussed. It is proposed that the main approaches in reducing the drift error are guaranteeing the rotor envelope surface to be an ideal spherical and improving the controlling precision of rotor displacement. The common problems associated in a gyroscope with a spherical rotor can be effectively resolved by the proposed method.

• 대한기계학회논문집
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• 제17권5호
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• pp.1095-1105
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• 1993

본 연구에서는 앞서 개발된 3차원 강소성 유한요소법을 이용하여 H-형강 압연 공정을 해석하여 그 타당성을 검토하고 이를 실제의 공정 설계에 이용할 수 있도록 하였다.

• Korea-Australia Rheology Journal
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• 제15권4호
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• pp.187-196
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• 2003

The recent renaissance in controlled-stress rheometry has meant that more and more commercial models of this type of instrument have appeared in the (rheological) marketplace and many papers now deal with the results obtained by their use. It is therefore both timely and appropriate that this mode of rheometry should be reviewed for the sake of new and old users who are probably not be aware of its development. The history of controlled-stress measurements is therefore given, and the particular efforts of the late Jack Deer in the 1970s are chronicled, and then the later developments that have made it possible that such low torques can now be applied and such low rotational speeds measured. These have been mostly in the areas of air bearing and optical disc technologies. The typical results now obtained are illustrated.