• 자동차안전학회지
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• 제13권1호
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• pp.6-13
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• 2021

This paper presents yaw moment control for modification of steering characteristic in rear-driven vehicle with front in-wheel motors (IWMs). The proposed control algorithm is designed to modify yaw rate response of the test vehicle. General approach for modification of steering characteristic is to define the desired yaw rate and track the yaw rate. This yaw rate tracking method can cause the chattering problem because of the IWM actuator response. Large overshoot and settling time in IWM torque response can amplify the oscillation in control input and yaw rate. To resolve these problems, open-loop IWM controller for cornering agility was designed to modify the understeer gradient of the vehicle. The proposed algorithm has been investigated via the computer simulations and the vehicle tests. The performance evaluation has been conducted on dry asphalt using E-segment test vehicle. The performance of the proposed algorithm has been compared to general yaw rate tracking algorithm in the vehicle tests. It has been shown that the proposed control law improved the cornering agility without chattering problem.

• 한국산학기술학회논문지
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• 제16권9호
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• pp.6247-6253
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• 2015

본 논문은 병렬 오차 증폭기 구조를 적용하여 과도응답특성 개선한 LDO 레귤레이터를 제안한다. 제안하는 LDO 레귤레이터는 고 이득, 좁은 주파수 대역의 오차증폭기 (E/A1)와, 저 이득, 넓은 주파수 대역의 오차증폭기 (E/A2)로 이루어지며, 두 오차증폭기를 병렬 구조로 설계해서 과도응답특성을 개선한다. 또한 슬루율을 높여주는 회로를 추가하여 회로의 과도응답특성을 개선하였다. 극점 불할 기법을 사용하여 외부 보상 커패시터를 온 칩 화하여 IC 칩 면적을 줄여 휴대기기 응용에 있어서도 적합하게 설계 하였다. 제안된 LDO 레귤레이터는 매그나칩/하이닉스 $0.18{\mu}m$ CMOS 공정을 사용하여 회로설계 하였고 칩은 $500{\mu}m{\times}150{\mu}m$ 크기로 레이아웃을 실시하였다. 모의실험을 한 결과, 2.7 V ~ 3.3 V의 입력 전압을 받아서 2.5 V의 전압을 출력하고 최대 100 mA의 부하 전류를 출력한다. 레귤레이션 특성은 100 mA ~ 0 mA에서 26.1 mV의 전압변동과 510 ns의 정착시간을 확인하였으며, 0 mA에서 100 mA의 부하 변동 시 42.8 mV의 전압 변동과 408 ns의 정착 시간을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1833-1837
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• 2004

The two-inertia system, which has the torsion vibration, is typically found in several industrial applications. This torsion vibration will effect the quality of the rolled material as well as the stability of the drive system. Thus the speed and torsion vibration of the system have to be properly controlled. This paper, I-PDA controller designed by Coefficient Diagram Method to control a two-inertia system is proposed. The experimental result shows that both of transient and steady state specification can be fulfilled but the transient response still has long rise time. In order to improve the speed of the system response, a phase lag structure of feedforward controller is introduced to I-PDA control system. It is shown that the performance of the I-PDA control system with suitable FFC has shorter rise and settling times, no overshoot and the torsion vibration can be suppressed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1007-1011
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• 2003

In this paper, a design of I-PDA controller by CDM to control a flow process whose structure is first order lag plus a dead time is introduced. The factor of dead time of the process is approximated by second order Pade approximation in order to get a third order system. The simulations show that both of the transient and steady state specifications can be fulfilled. However, the transient response of the I-PDA control system still has long rise time. Then, a feedforward controller (FFC) with two adjustable parameters and one derivative time is introduced into I-PDA control system for improving the speed of the system response. It is shown, from the simulation results, that the performance of the I-PDA control system with suitable FFC has shorter rise time and no overshoot, while settling time remains almost the same. The performance comparison of the proposed control system with the PI control system with and without FFC is also made.

• Journal of Biosystems Engineering
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• 제29권5호
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• pp.407-418
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• 2004

There are several different types of continuously variable transmission(CVT) such as toroidal drive, belt drive, hydrostatic drive, hydro-mechanical drive. The toroidal CVT is an alternative to the manual transmission, HST, power-shift gear trans-missions or other CVTs. The driver of the CVT tractor doesn't have to operate a shia lever since the CVT controller automatically controls the speed of tractor. Thus, it is much easier to operate the CVT tractor. The fuel efficiency of CVT tractor can be increased since the controller responds quickly to the change in external load on the wheel during field operation. This study was conducted to develop the hardwares and softwares for the toroidal CVT controller which control the variator and the range clutches. The hardware consisted of a measurement system, hydraulic system and computer. And the PID controller was developed using the simulation model of the CVT control system. Through the simulation, the control coefficients for the PID controller were selected. Finally, the performance of the CVT control system was evaluated by step response test and torque response test. The settling time of the CVT control system appeared to be fast enough for field operations.

• 전기학회논문지
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• 제59권1호
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• pp.176-183
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• 2010

This paper presents some practical design issues that should be carefully considered when a notch filter is included in a linear feedback controller. A notch filter is generally used to compensate the effects of resonant modes that may result in poor performance. It is very common that the practical engineers prefer to add such a notch filter after having previously designed a feedback controller without the filter. It is known that the resulting performance by this approach is not seriously different from when a feedback controller is designed for a plant previously compensated by a notch filter. However, we will point out that there are some cases where both approaches have different performances. In order to show this, a low-order controller design using the partial model matching method has been applied to a linear time invariant (L Tn model. The results suggest that there is a tendency to achieve much better time responses in terms of reducing the overshoot and shortening the settling time, and in the frequency domain characteristics such as the sensitivity function and the stability margins when the design of a feedback controller after including a notch filter is carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1242-1244
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• 1992

This Paper deals with a Auto-Tuning Fuzzy PID Controller used in real time and its application for induction motor. The control strategy of the controller is able to develop and improve automatically. The new Auto-Tuning Fuzzy PID Control algorithm which modifies the fuzzy control decision table is presented in this paper. It can automatically refine an initial approximate set of fuzzy rules. The possibility of applying fuzzy algorithms in faster response, and more accurate was compared with other industrial processes, such as AC Motor driver. The performance of Proportional_Integral Derivative(PID) control and this fuzzy controllers is compared in terms of steady_state error, settling time, and response time. And then, Limitations of fuzzy control algorithms are also described.

• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.77-83
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• 1995

Recently, in the field of industrial servo-systems, several methods have been proposed for tracking the reference input fastly and finely without overshoot. These methods, however, are established under hypothesis that structure and parameters of the plant are known accurately and they are time invariant. In practice, it is difficult to obtain the values of plant's parameters accurately and usually plants change with time and operation conditions. In this paper a method to construct the nominal model tracking adaptive control system is proposed. The system is composed of the nomial model which produces a ideal response and the model tracking system with the fuzzy adaptive controller. If the actual plant is equal to the controlled object in the nominal model, the output of the plant is the same as that of the nominal model and the fuzzy adaptive controller becomes idle. However, when the plant changes, the fuzzy adaptive controller of the tracking system operates in order for the output of the plant to track the ideal response. Through the computer simulations under various conditions, it is confirmed that the proposed model tracking system is very effective.

• 설비공학논문집
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• 제5권2호
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• pp.94-101
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• 1993

Recently, efforts of decreasing energy consumption are continously increased and user's preference is also diversified in refrigeration and air conditioning systems. Thus, in order to satisfy these demands, high efficiency, high intelligence, and energy saving for those systems are essential. As the basic study for diverse functions and intelligence of those systems, we investigated the response characteristics through the compressor capacity control concerned with superheat and refrigeration room temperature. And, response characteristics are investigated experimentally by using micro computer based PWM inverter control method. Experimental result of the conventional on-off control method is given in order to be compared to the results of inverter control method. The results obtained through this study are summarized as follows. It is shown from the experimental results of the on-off control method that the range of temperature variation around the steady state ($-18^{\circ}C$) is very large (about $7{\sim}8^{\circ}C$) and the settling time bringing the steady state is not found. In the inverter control method, we can see that the refrigeration room temperature after reaching the setting temperature is very stable without fluctuation and a robust control for disturbance such as opening the door has been realized.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.158-160
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• 2005

This paper presents a new approach to the problem of designing a cascaded three-parameters controller for a given linear time invariant (LTD plant in unity feedback system. We consider a proportional-integral-derivative (PID) and a first-order controller with specified overshoot and settling time. This problem is difficult to solve because there may be no analytical solution due to the use of low-order controller and furthermore. the zeros of controller just appear in the zeros of feedback system. The key idea of our method is to impose a constraint on the controller parameters so that the zeros of resulting controller are distant from the dominant pole of closed-loop system to the left as far as the given interval. Two methods realizing the idea are suggested. We have employed the characteristic ratio assignment (CRA) in order to deal with the time response specifications. It is noted that the proposed methods are accomplished only in parameter space. Several illustrative examples are given.