• 제어로봇시스템학회논문지
• /
• 제6권9호
• /
• pp.752-757
• /
• 2000

This paper considers a decentralized control problem of dicrete LTI systems which have time delay between interconnections. This paper provides sufficient conditions for the decentralized controller to exist as a H$\infty$ disturbance attenuation ${\gamma}$ of a scaled system and shows that the controller can be designed by using the discrete standard $H_{\infty}$ control theory.

• 제어로봇시스템학회논문지
• /
• 제14권3호
• /
• pp.254-262
• /
• 2008

In this paper, we propose an adaptive neural dynamic surface control (DSC) approach with $H_{\infty}$ tracking performance for full dynamics of nonlinear flight systems. It is assumed that the model uncertainties such as structured and unstrutured uncertainties, and external disturbances influence the nonlinear aircraft model. In our control system, self recurrent wavelet neural networks (SRWNNs) are used to compensate the model uncertainties of nonlinear flight systems, and an adaptive DSC technique is extended for the disturbance attenuation of nonlinear flight systems. All weights of SRWNNs are trained on-line by the smooth projection algorithm. From Lyapunov stability theorem, it is shown that $H_{\infty}$ performance nom external disturbances can be obtained. Finally, we present the simulation results for a nonlinear six-degree-of-freedom F-16 aircraft model to confirm the effectiveness of the proposed control system.

• 한국군사과학기술학회지
• /
• 제5권1호
• /
• pp.75-82
• /
• 2002

In this paper, the robust PID(Proportional-Integral-Derivative) controller was designed for speed control of BLDC motors using the frequency region model matching method. It was designed the robust PID controller satisfying disturbance attenuation and robust tracking performance using an H$\infty$ control method. The robust PID controller gains with the performances of the designed H$\infty$ controller are determined using the model matching method at frequency domain. Consequently, simulation results show that the proposed PID speed controller satisfies load torque disturbance attenuation and robust tracking performance, and this study has usefulness and applicability for the speed control system design of BLDC motors.

• 제어로봇시스템학회논문지
• /
• 제10권5호
• /
• pp.402-410
• /
• 2004

To obtain a good tracking performance in an optical disk drive servo system, it is essential to attenuate periodic disturbances caused by eccentric rotation of the disk. As an effective control scheme for enhancing disturbance attenuation performance, disturbance observers (DOBs) have been successfully applied to the track-following servo system of optical disk drives. In disk drive systems, the improvement of data transfer rate has been achieved mainly by the increase of disk rotational speed, which leads to the increase of the disturbance frequency. Conventional DOBs are no longer effective in disk drive systems with a high-speed rotation mechanism because the performance of conventional DOBs is severely degraded as the disk rotational frequency increases. This paper proposes a new DOB structure for effective rejection of the disturbance in optical disk drives with a very high rotation speed. Asymptotic disturbance rejection is achieved by adopting a band-pass filter in the DOB structure, which is tuned based on the information on the disturbance frequency. In addition, performance sensitivity of the proposed DOB to changes in disk rotational frequency is analyzed. The effectiveness of the proposed DOB is verified through simulations and experiments using a DVD-ROM drive.

• 전기학회논문지
• /
• 제66권4호
• /
• pp.666-671
• /
• 2017

A disturbance-observer-based adaptive neural tracker design problem is investigated for a class of perturbed uncertain non-affine nonlinear systems with unknown control direction. A nonlinear disturbance observer (NDO) design methodology using neural networks is presented to construct a tracking control scheme with the attenuation effect of an external disturbance. Compared with previous control results using NDO for nonlinear systems in non-affine form, the major contribution of this paper is to design a NDO-based adaptive tracker without the sign information of the control coefficient. The stability of the closed-loop system is analyzed in the sense of Lyapunov stability.

• 한국식품영양과학회지
• /
• 제45권3호
• /
• pp.313-320
• /
• 2016

본 연구에서는 라벤더, 캐모마일, 레몬버베나, 타임, 바질의 복합 열수 추출물이 수면을 촉진하고 스트레스를 완화하는지 확인하기 위하여 농도에 따라 동물모델에 미치는 효과를 관찰하였다. 허브 복합추출물(HME)을 10, 30, 100 mg/kg의 농도로 3주간 구속 스트레스 모델과 수면장애 모델에 각각 경구투여 하였고, 실험 결과 구속 스트레스를 유도한 동물모델에서 HMEII군(30 mg/kg)과 HMEIII군(100 mg/kg)은 혈장 내 코티졸과 IL-6 함량을 감소시켰으며, HMEIII군은 체중 대비 부신 무게도 유의적으로 회복시킨 것을 확인하였다. 수면장애 모델에서는 HMEIII군이 대조군에 비해 체중이 증가하였고, HME II, III군은 혈장 내 멜라토닌 수치를 높였으며 코티졸 수치를 감소시켰다. 이러한 결과를 통해 본 실험에서 사용한 허브 복합추출물이 농도에 따라 스트레스 완화와 수면장애 개선에 효과가 있음을 확인하였다.

• 전기학회논문지
• /
• 제66권1호
• /
• pp.66-71
• /
• 2017

In this paper, we study the robustness of disturbance observer based controller for DC motor in the presence of unmodeled dynamics. It is well known that the robustness property usually becomes weaker as the control gain becomes larger. On the contrary to this expectation, it is shown that the phase margin of DOB controller remains quite a large value even though the time constant of Q-filter becomes smaller. The computer simulation results show that DOB controller is able to stabilize the motor system even in the presence of unmodeled dynamics. On the contrary, the unity-feedback system fails to maintain stability when a high gain feedback is employed for the purpose of achieving better disturbance attenuation performance.

• 조명전기설비학회논문지
• /
• 제28권5호
• /
• pp.15-22
• /
• 2014

The automobile cruise control system tries to maintain a constant velocity in the face of disturbance mainly caused by mass changes or changes in the slope of a road. The controller should compensate for such disturbances and model uncertainties. In this paper, we study on the disturbance observer based controller for cruise control system. In the presence of disturbances and model uncertainties, we carry out computer simulations in order to compare the performance of the conventional PI controller and DOB controller. From the simulation results, we found that the performance of DOB controller is superior to that of the conventional PI controller.

• 한국정밀공학회지
• /
• 제17권8호
• /
• pp.126-133
• /
• 2000

This paper is a study on robust PID controller tuning technique using the frequency region model matching method.To design the robust PID controller satisfying disturbance attenuation and robust tracking property for a reference input first an {{{{ETA _$\infty$}}}} controller satisfying given performances is designed using an H$_{\infty}$ control method, And then the parameters(proportional gain integral gain and derivation gain) of the robust PID controller with the performances of the desinged H$_{\infty}$ controller are determined using the model matching method at frequency domain. in this paper this PID controller tuning technique is applied to PID speed controller design for BLDC motors. Consequently simulation results show that the proposed PID speed controller satisfies load torque disturbance attenuation and robust tracking property and this study has usefulness and applicability for the speed control system; design of BLDC motors.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.113-116
• /
• 1997

In this paper, we present a robust $H^{\infty}$ controller design method for parameter uncertain time-varying systems with disturbance and that have time-varying delays in both state and control. It is found that the problem shares the same formulation with the $H^{\infty}$ control problem for systems without uncertainty. Through a certain differential Riccati inequality approach, a class of stabilizing continuous controller is proposed. For parameter uncertainties, disturbance and time varying delays, proposed controllers the plant and guarantee an $H^{\infty}$ norm bound constraint on disturbance attenuation for all admissible uncertainties. Finally a numerical example is given to demonstrate the validity of the results.ts.