• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.119-121
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• 2007

PID control is windely used to control stable processes, however, its application to integrating processes is less common. In this paper, we proposed a simple PID controller tuning method for integrating processes with time delay to meet a sensitive function $M_s$. With the proposed PID tuning method, we can obtain stable integrating processes using PD controller in inner feedback loop and a loop transfer function with desired stable specification. This guarantees both robustness and performance. Simulation examples are given to show the good performance of the proposed tuning method to other methods.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.266-271
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• 1992

This paper presents a new stable composite control law for the flexible joint robot manipulators, which incorporate the additional stabilizing control law with sliding property. The singularly perturbated models include inertia moments functions of the deformations of actuator. The newly defined fast controller variable is computed from the corrected reduced-order model without additional computational loads. The simulations for 2 DOF flexible joint manipulator show that the proposed schemes are more stable than conventional one, and especially effective for the manipulator with high joint-flexibilities.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.395-403
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• 2020

This study presents a stable start-up strategy for v/f scalar-controlled permanent magnet synchronous motors (PMSMs). The v/f-controlled PMSMs easily lose synchronism under low-speed conditions if an insufficient stator voltage is applied to the machine due to errors in measured motor parameters and inverter nonlinearity, such as inverter dead time and on-state voltage drop. The proposed method adopts the I/f control method to ensure a stable start at low speeds and then switches to the v/f control method at medium speeds. A smooth transition method from I/f control to v/f control is proposed to minimize the oscillation of the stator current and rotor speed during transition. Moreover, the stability of the I/f and v/f control methods is analyzed using a small-signal model. Simulation and experimental results are provided to verify the performance of the proposed control strategy.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.97-100
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• 1997

A new control method for the robust position control of a brushless DC(BLDC) motor using the asymptotically stable adaptive load torque observer is presented. A precision position control is obtained for the BLDC motor system approximately linearized using the field-orientation method. And the application of the load torque observer is published in [1] using fixed gain. However, the flux linkage is not exactly known for a load torque observer. Therefore, a model reference adaptive observer is considered to overcome the problem of the unknown parameter in this paper. And stability analysis is carried out using Liapunov stability theorem. As a result, asymptotically stable observer gain can be obtained without affecting the overall system response. The load disturbance detected by the asymptotically stable adaptive observer is compensated by feedforwarding the equivalent current having the fast response.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2271-2274
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• 2005

The desired ZMP is different from the actual ZMP of a humanoid robot during actual walking and stand upright. A humanoid robot must maintain its stable posture although external force is given to the robot. A humanoid robot can know its stability with ZMP. Actual ZMP may be moved out of the foot-print polygons by external disturbance or uneven ground surfaces. If the position of ZMP moves out of stable region, the stability can not be guaranteed. Therefore, The control of the ZMP is necessary. In this paper, ZMP control algorithm is proposed. Herein, the ZMP control uses difference between desired ZMP and actual ZMP. The proposed algorithm gives reaction moment with ankle joint when external force is supplied. 3D simulator shows motion of a humanoid robot and calculated data.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.35-43
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• 2008

The control of underactuated mechanical system is very complex for the loss of its control inputs. The model of underactuated mechanical systems in a potential field is built with Lagrangian method and its structural properties are analyzed in detail. A genetic algorithm (GA)based stable control approach is proposed for the class of under actuated mechanical systems. The Lyapunov stability theory and system properties are utilized to guarantee the system stability to its equilibrium. The real-valued GA is used to adjust the controller parameters to improve the system performance. This approach is applied to the underactuated double-pendulum-type overhead crane and the simulation results illustrate the complex system dynamics and the validity of the proposed control algorithm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.215-220
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• 1988

The oscillatory hydraulic servosystem and the stable hydraulic servosystem under proportional control were feedback-controlled respectively using the estimated states of the observer. The observer was constructed in the analog computer and then it was interfaced with the real hydraulic servosystem to excute the experiment. As a result of experiment, the system that had been stable under proportional control responded more rapidly than before and the system that had shown oscillatory phenomenon under proportional control became stable with the same maximum acceleration and velocity that it had started under proportional control.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.442-442
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• 2000

The intelligent auto-tuning method fur a strongly stable adaptive control system of a DC motor with great load inertia variation is proposed. The stable characteristic polynomial that is designed by an optimal servo is specified for the adaptive pole placement control system. The appropriate adaptive control system can be derived, by adjusting automatically the weight of a performance criterion in optimal control by means of the fuzzy inference on the basis of the stability index.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1440-1443
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• 2004

Most previous robots had used the wheels as means for movement. These structures were relatively simple and easy to control and this is why the method had been used until currently. However, there are many realistic problems to move from one place to another in human life, for instance, steps and edges. So we need to develop the two-legged walking humanoid robot. The 2-legged walking Robot system has been vigorously developed in so many corporations and academic circles of several countries. However, 2-legged walking Robot has been mostly studied in view of the static walk. We design a stable humanoid Robot which can walk in high-speed through the research of the dynamic walk in this paper. Especially, worldwide companies have been interested in developing humanoid robots for a long time to solve the before mentioned problems so that they can become more familiar with the human form. The most important thing, for the novel two-legged walk, is to create a stable and fast walking in two-legged robots. For realization of this movement, an optimal mechanical design of 12 DOFS, a distributed control and a parallel processing control are implemented in this paper. This paper proves that high speed and stable walking can be achieved, through experiments.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.125-132
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• 2002

This paper shows an experimental magnetic levitation table using one degree-of-freedom active control. The magnetic levitation table using repulsions of permanent magnets was theoretically presented already. Thus the objective of this paper is to prove stable levitation with only one degree-of-freedom active control experimentally. For the design of the system, at first, permanent magnets are selected. Secondly, the spring constants of the virtual spring are obtained by simulation. Thirdly, the moving magnets are arranged using a stable layout relation. Fourthly, a linear voice coil motor is designed. Finally, the magnetic levitation system is manufactured. The phenomenon of stable levitation in the manufactured table is proven by means of dynamic time and frequency responses. The differences between the theoretical natural frequencies and experimental ones are analyzed. Also, stable range in the control direction is shown experimentally.