• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2249-2251
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• 2001

This paper proposes that it minimizes interference between link at high speed trajectory tracking of 2-degree parallel link manipulator and QFT(Quantitative Feedback Theory) controller which robust structure uncertainty and disturbance of plant. And using ICD(Individual Channel Design), it separates two channel from multivariable system, parallel link manipulator and designs robust controller with applying MISO QFT to each channel. Finally, we make sure of robustness and excellence of QFT controller through simulation and experiment.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.81-90
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• 2000

Parallel manipulator is suitable for the high precise task because it than has higher stiffness, larger load capacity and more excellent precision, due to the closed-lop structure, than serial manipulator. But the controller design for parallel manipulator is difficult because the parallel manipulator has both the complexity of structure and the interference of actuators. The precision improvement of parallel manipulator using a classical linear control scheme is difficult because the parallel manipulator has the tough nonlinear characteristics. In this paper, firstly, the kinematic analysis of a parallel manipulator used at the experiments is performed so as to show the controllability. The analysis of internal singular configuration of the workspace is performed using the kinematic isotropic index so a sto show the limitation of control performance of a simple linear controller with fixed control gains. Secondly, a control scheme is designed by using an adaptive fuzzy logic controller so that active joints of the parallel manipulator track more precisely the desired input trajectory. This adaptive fuzzy logic controller so that active joints of the parallel manipulator track more precisely the desired input trajectory. This adaptive fuzzy logic controller is often used for the control of nonlinear system because it has both the inference ability and the learning ability. Lastly, the effeciency of designed control scheme is demonstrated by the real-time control experiments with IBM PC interface logic H/W and S/W of my won making. The experimental results was a success.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.102-111
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• 2005

In this paper, we address a position control for a parallel stage, which is levitated and driven by electric magnetic force. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal force. A dynamic equation of the stage system is derived based on Newton-Euler method and it's special Jacobian matrix describing a relation between the limited velocity and Cartesian velocity is done. There are proposed two control methods for positioning which are Cartesian space controller and Actuator space controller. The control performance of the Cartesian space controller is better than the Actuator space controller in task space trajectory while the Actuator space controller is simpler than the Cartesian space controller in controller realization.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.179-184
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• 2008

This paper presents the design of the feed forward controller to improve on the non-interference control performance of a single PWM converter in parallel for high-speed trains. The feed forward controller is designed to minimize the interference generated by converter switching in parallel operation of PWM converters. The gain value of the feed forward controller is calculated by inductance values of the input transformer. However, it is difficult to decide this gain value exactly because inductance values are changed by the operation condition of an input transformer. In this paper, the proposed design of feed forward controller can exactly decide the gain value using the leakage inductances estimated by detecting the variation of input current. the validity of the proposed feed forward controller is proved through the simulation results.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.161-172
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• 2007

This article suggests an inverse kinematics analysis of a two degree of freedom spatial parallel motion simulator and design methodology of the robust PID controller. The parallel motion simulator consists of a fixed base and a moving frame connected by two serial chains, with each serial chain containing one revolute joint and two passive spherical joint. First, an inverse kinematics problems are solved in order to find the joint variable necessary to bring the end effector to track the desired trajectory. Second, an inverse optimal PID controller is proposed to track trajectories in the face of uncertainty. And the $H_{\infty}$ optimality and robust stability of the closed-loop system is acquired through the PID controller. Finally numerical results show the effectiveness of the PID controller that is designed by square/linear tuning laws.

• Journal of Power Electronics
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• v.18 no.2
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• pp.502-510
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• 2018

A circulating current is a major problem caused by directly connecting voltage-source inverters (VSIs) in parallel. This circulating current occurs as a zero-sequence current between the inverters by specific switch states. Several studies have presented alternatives using hardware and software methods. When coupled inductors (CIs) are employed for the high-frequency circulating current, a controller is required to prevent the low-frequency circulating current from saturating the CIs. In this study, the zero-sequence circulating current and its alternatives are investigated using hardware and mathematical description. A high-performance circulating current controller is proposed by applying a repetitive controller to the zero-sequence current control loop. The proposed controller can effectively minimize the low-frequency circulating current without any data sharing between the inverters in unfavorable conditions. It can also be applicable to the modular configuration of parallel three-phase VSIs. Experimental results verify the performance of the proposed controller.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2251-2260
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• 2021

The motion control of the divertor maintenance system of the China Fusion Engineering Test Reactor (CFETR) was studied in this paper, in which CFETR Multi-Functional Maintenance Platform (MFMP) was simplified as a parallel robot for the convenience of theoretical analysis. In order to design the motion controller of parallel robot, the kinematics analysis of parallel robot was carried out. After that, the dynamic modeling of the hydraulic system was built. As the large variation of heavy payload on MFMP and highly nonlinearity of the system, A Fuzzy-PID controller was built for self-tuning PID controller parameters by using Fuzzy system to achieve better performance. In order to test the feasibility of the Fuzzy-PID controller, the simulation model of the system was built in Simulink. The results have showed that Fuzzy-PID controller can significantly reduce the angular error of the moving platform and provide the stable motion for transferring the divertor.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.590-596
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• 2004

A passivity-based dynamic output feedback controller design is considered for a finite collection of non-square linear systems. Design of a single controller for a set of plants i.e. simultaneous stabilization is an important issue in the area of robust control design. We first determine a squaring gain matrix and an additional dynamics that is connected to the systems in a feedforward way, then a static passivating control law is designed. Consequently, the actual feedback controller will be the static control law combined with the feedforward dynamics. A necessary and sufficient condition for the existence of the parallel feedforward compensator is given by the static output feedback formulation. In contrast to the previous result [1], a technical condition for constructing the parallel feedforward compensator is removed by proposing a new type of the parallel compensator.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2501-2513
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• 1994

In this paper, a compact, light-weight, universal, spherical 3-degree-of-freedom, parallel-structured manual controller with high reflecting-force capability is implemented. First, the position analysis, kinematic modeling and analysis, force reflecting transformation, and applied force control schemes for a parallel structured 3 degree-of-freedom spherical system have been described. Then, a brief description of the system integration, its actual implementation hardware, and its preliminary analysis results are presented. The implemented parallel 3 degree-of-freedom spherical module is equipped with high gear-ratio reducers, and the friction due to the reducers is minimized by employing a force control algorithm, which results in a "power steering" effect for enhanced smoothness and transparency (for compactness and reduced weight).d weight).

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.200-209
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• 1999

This paper presents a precise tracking control scheme for the proposed parallel robot using artificial neural network. This control scheme is composed of three feedback controllers and one feedforward controller. Conventional PD controller and artificial neural network are used as feedback and feedforward controller respectively. A backpropagation learning strategy is applied to the training of artificial neural network, and PD controller outputs are used as target outputs. The PD controllers are designed at the robot dynamics based on inter-relationship between active joints and moving platform. Feedback controllers insure the total stability of system, and feedforward controller generates the control signal for trajectory tracking. The precise tracking performance of proposed control scheme is proved by computer simulation.