• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.272-275
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• 1989

In this paper feedback linearization of valve-controlled nonlinear hydraulic velocity control system is studied. The $C^{\infty}$ nonlinear transformation T is obtained, and it is shown that this transformation is global one. Linear equivalence of nonlinear hydraulic velocity control system is obtained by this global nonlinear transformation, and linear state feedback control law is applied to this linear model. It is shown that this transformation method is to the linear approximation by simulation study..

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.713-721
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• 2008

This paper presents the robust velocity estimation of an omnidirectional mobile robot using a polygonal array of optical mice that are installed at the bottom of the mobile robot. First, the velocity kinematics from a mobile robot to an array of optical mice is derived as an overdetermined linear system. The least squares velocity estimate of a mobile robot is then obtained, which becomes the same as the simple average for a regular polygonal arrangement of optical mice. Next, several practical issues that need be addressed for the use of the least squares mobile robot velocity estimation using optical mice are investigated, which include measurement noises, partial malfunctions, and imperfect installation. Finally, experimental results with different number of optical mice and under different floor surface conditions are given to demonstrate the validity and performance of the proposed least squares mobile robot velocity estimation method.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1853-1857
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• 2005

In most of motor-driven motion control systems, an encoder is used to measure a position of the motor and the velocity information is obtained by measuring the position increment over a sampling period. The quantization effect due to limited resolution of the encoder induces some measurement errors, and consequently causes deterioration of the motion performance especially in low velocity. In this paper, we propose a gain-scheduled acceleration estimator which works in wider velocity range than the original acceleration estimator. We investigate and analyze characteristics of the velocity measurement mechanism which takes into account the quantization effect of the encoder. Next, we introduce the acceleration estimator and propose a gain-scheduled acceleration estimator. The bandwidth of the gain-scheduled acceleration estimator is automatically adjusted by the velocity command. Finally, its performance is evaluated by simulation and experiment, and the results are compared with those of a conventional method and the original acceleration estimator.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.477-483
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• 2002

This paper deals with a workspace analysis of multi-legged walking robots in velocity domain(velocity workspace analysis). Noting that when robots are holding the same object in multiple cooperating robotic arm system the kinematic structure of the system is basically the same with that of a multi-legged walking robot standing on the ground, we invented a way ot applying the technique for multiple arm system to multi-legged walking robot. An important definition of reaction velocity is made and the bounds of velocities achievable by the moving body with multi-legs is derived from the given bounds on the capabilities of actuators of each legs through Jacobian matrix for given robot configuration. After some assumption of hard-foot-condition is adopted as a contact model between feet of robot and the ground, visualization process for the velocity workspace is proposed. Also, a series of application examples will be presented including continuous walking gaits as well as several different stationary posture of legged walking robots, which validate the usefulness of the proposed technique.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1136-1141
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• 2015

In this paper, we develop a sliding mode controller that uses a nonlinear sliding manifold for the permanent magnet synchronous motor. The proposed controller makes sure that both currents and velocity tracking error converge into equilibria. Nonlinear sliding manifold consists of current dynamics and nonlinear functions which are designed with velocity tracking error and its integrated term. The nonlinear functions are designed to guarantee that velocity tracking error converge into zero. The closed-loop stability is proven by Lyapunov theory. The effectiveness of proposed method is demonstrated by numerical simulation results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.40-46
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• 2008

This paper presents the optimal motion control for 3-axis SCARA robot by using $LabVIEW^{(R)}$. Specifically, for optimal motion control of 3-axis SCARA robot, we study velocity profile based on finite jerk(the first derivative of acceleration) and optimal gain tunig based on frequency response method by using $LabVIEW^{(R)}$. The velocity optimization with finite jerk aims at generating the smooth velocity profile of robot. Velocity profile based on finite jerk is acquired and applied to 3-axis SCARA robot by using $LabVIEW^{(R)}$. DSA(Dynamic Signal Analyzer) for frequency response method is programed by using $LabVIEW^{(R)}$. We obtain the bode plot of transfer function about 3-axis SCARA robot by using DSA, and perform the gain tuning considering dynamic characteristic based on the bode plot. These experiments have shown that the proposed motion control can reduce vibration displacement and response error rate each 33.7% and 51.7% of 3-axis SCARA robot.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.5-11
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• 2015

In a pressurized water reactor (PWR), control rod assembly (CRA) falls into the guide tubes of a fuel assembly due to gravity for scram. Various theoretical approaches and numerical analyses have been performed because its shape is simple and its design was completely developed several decades ago. A control rod assembly for a sodium-cooled faster reactor (SFR) which is geometrically more complicated is being actively developed in Korea nowadays. Drop time and impact velocity of a CRA are important parameters with respect to reactivity insertion time and the mechanical robustness of a CRA and a guide duct. In this paper, computational method considering simultaneously the equation of motion for rigid body and the Navier-Stokes equations for fluid is suggested and verified by comparison with theoretical analysis results. Through this valuable CFD analysis method, drop time and impact velocity of initially designed SFR CRA are evaluated before performing scram tests with it.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1427-1439
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density (${\gamma}_d$) and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of $OMC{\pm}2%$ as well as the p-wave velocity.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.774-781
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• 2013

The purpose of this paper is to design a DVL-RPM based VKF (Velocity Kalman Filter) design for a performance improvement underwater integrated navigation system. The proposed approach relies on a VKF, augmented by a altitude from Echo-sounder based switching architecture to yield robust performance, even when DVL (Doppler Velocity Log) exceeds the measurement range and the measured value is unable to be valid. The proposed approach relies on two parts: 1) Indirect feedback navigation Kalman filter design, 2) VKF design. To evaluate proposed method, we compare the results of the VKF aided navigation system with simulation result from a PINS (Pure Inertial Navigation System) and conventional INS-DVL method. Simulations illustrate the effectiveness of the underwater navigation system assisted by the additional DVL-RPM based VKF in underwater environment.