• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.151.1-151
• /
• 2001

This paper establishes some integral equalities formulated by zeros located in the convergence region of Laplace transformable function. Using the definition of Laplace transform, it is shown that time-domain integral equalities have to be satisfied by the function, and those can be applied to understanding of the fundamental limitations of the control system represented by the transfer function, which has been Laplace transform. In the unity-feedback control scheme, another integral equality is also derived on the output response of the system with open-loop poles and zeros located in the convergence region.

• 한국통신학회논문지
• /
• 제16권10호
• /
• pp.981-991
• /
• 1991

LQG의 강인성 증진을 위하여 제안된 LGQ/LTR방법은 비 최소위상 플랜트에 대하여 적용할 수 없는 이론적 제한성을 갖는다. 본 논문에서는 비 최소위상 플랜트에 대해서도 적용될 수 있는 세 단계로 구성된 새로운 LQG/LTR방법을 제안한다. 첫번째 단계로 주어진 비 최소위상 플랜트를 최소위상 플랜트로 근사화 시키기 위한 부가적인 feed-forward 보상기를 설계하며 다음 단계에서 전개사양에 맞도록 근사화된 비 최소위상 플랜트에 대하여 목표 루우프를 설계한다. 마지막 단계로 개루우프의 전달함수가 목표 루우프로 회복시키는 LTR을 설계한다. 제안된 방법이 비 최소위상 플랜트에 대한 제약을 해결할 수 있음을 시뮬레이션 예제를 통하여 보인다.

• 한국통신학회:학술대회논문집
• /
• 한국통신학회 1984년도 추계학술발표회논문집
• /
• pp.43-47
• /
• 1984

This paper describes the mean time delay and its variance before transition from search to lock mode by means of signal flow graph and its transfer function. A relation between hit probability and search stage number is presented with the comparison of the open loop and closed loop. From these results optimum transition probability which we must hold can be obtained.

• 한국소음진동공학회논문집
• /
• 제21권10호
• /
• pp.940-950
• /
• 2011

This paper reports a filtered velocity feedback(FVF) controller, which is an alternative to direct velocity feedback(DVFB) controller. The instability problems at high frequencies due to non-collocated sensor/actuator configuration with the DVFB can be alleviated by the proposed FVF controller. The FVF controller is designed to filter out the unstable high frequency response. The dynamics of a clamped plate under forces and moments and the FVF controllers are formulated. The stability of the control system and performance are investigated with the open loop transfer function(OLTF). It is found that the FVF controller has a higher gain margin than the corresponding DVFB controller owing to the rapid roll-off behavior at high frequencies. Although the gain margin cannot be fully utilized because of the enhancement at the high frequencies, the vibration at the modes lower than the tuning frequency is well controlled. This performance of the FVF controller is shown to be improved from that of the DVFB controller. It is, however, noted that the stability around the tuning frequency is very sensitive so that the enhancement in vibration level should be followed. The reduction performance at low frequencies using the FVF controller should be compromised with the enhancement in the vibration at high frequencies while designing the controller.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 B
• /
• pp.1005-1008
• /
• 1996

일부궤한 제어시스템이 안정화되는 비례보상기의 이득의 구간을 연구한다. 이 논문에서 제어시스템이 연결된 구간에 대하여 안정화되는 조건을 구한다. 연결된 구간은 그 구간에 있는 어떤 임의의 두 실수를 취할 때 두 실수 사이의 모든 실수가 그 구간에 속하는 경우를 말한다. 조건은 페루프 전달함수의 분자나 분모의 주파수를 매개변수로한 부등식으로 표현된다. 또한 이산 시간 제어시스템과 시간지연 연속시스템에 관한 조건도 구한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.262-264
• /
• 1996

This paper presents a new dual loop control using novel vector phase locked loop(VP-PLL) for a high power static var compensator(SVC) with three-level GTO voltage source inverter(VSI). Through circuit DQ-transformation, a simple dq-axis equivalent circuit is obtained. From this, DC analysis is carried out to obtain maximum controllable phase angle ${\alpha}_{max}$ per unit current between the three phase source and the switching function of inverter, and AC open-loop transfer function is given. Because ${\alpha}_{max}$ becomes small in high power SVC, this paper proposes VP-PLL for more accurate $\alpha$-control. As a result, the overall control loop has dual loop structure, which consists of inner VP-PLL for synchronizing the phase angle with source and outer Q-loop for compensating reactive power of load. Finally, the validity of the proposed control method is verified through the experimental results.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
• /
• pp.1147-1156
• /
• 1993

In order to analyze lateral control in the backward maneuver of a tractor -trailer combination , a kinematic vehicle model and a human operator model with time delay were utilized for the operator/vehicle system. The analysis was carried out using the frequency domain approach. The open-loop stability of the vehicle motion was analyzed through the transfer functions. The sensitivity of the stability of the vehicle motion. to a change in the steering angle, was also analyzed. A mathematical model of the closed -loop operator/vehicle system was then formulated. The closed -loop stability of the operator /vehicle system was then analyzed. The effect of the delay time on the system was also analyzed through computer simulation.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1396-1406
• /
• 2016

A novel controller design is presented for the recently proposed electric springs (ESs). The dynamic modeling is analyzed first, and the initial Bode diagram is derived from the s-domain transfer function in the open loop. The design objective is set according to the characteristics of a minimum phase system. Step-by-step optimizations of the Bode diagram are provided to illustrate the proposed controller, the design of which is different from the classical multistage leading/lagging design. The final controller is the accumulation of the transfer function at each step. With the controller and the recently proposed δ control, the critical load voltage can be regulated to follow the desired waveform precisely while the fluctuations and distortions of the input voltage are passed to the non-critical loads. Frequency responses at any point can be modified in the Bode diagram. The results of the modeling and controller design are validated via simulations. Hardware and software designs are provided. A digital phase locked loop is realized with the platform of a digital signal processor. The effectiveness of the proposed control is also validated by experimental results.

• 유공압시스템학회논문집
• /
• 제8권2호
• /
• pp.23-28
• /
• 2011

This paper investigates the motion control of a hydraulic motor-load system using the Simple Adaptive Control (SAC) method. The plant transfer function has been modelled mathematically. The open-loop responses have been obtained experimentally in order to identify the design parameters of transfer function. The hydraulic motor-load system has been modelled using the 3D CAD and imbedded in the hydraulic circuit simulation program to verify the overall performance. The experimental results confirm that the SAC method gives a good tracking performance compared to the PID control.

• International Journal of Control, Automation, and Systems
• /
• 제1권1호
• /
• pp.76-82
• /
• 2003

This paper establishes some integral equalities formulated by zeros located in the convergence region of a Laplace transformable function. Using the definition of the Laplace transform, it shows that Laplace transformable functions have to satisfy the integral equalities in the time-domain, which can be applied to the understanding of the fundamental limitations on the control system represented by the transfer function. In the unity-feedback control scheme, another integral equality is derived on the output response of the system with open-loop poles located in the convergence region of the output function. From these integral equalities, two sufficient conditions related to undershoot and overshoot phenomena in the step response, respectively, are investigated.