Iterative Design of the Reduced-order Controller for the H<SUB>∞</SUB> Loop-shaping Method under Open-loop Magnitude Constraints and Application to Gain-scheduling Control

Masashi Yamamoto,Kazuhiro Yubai,Junji Hirai 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

The H∞ loop-shaping method is known to be an effective control method, however, it has two drawbacks. The first is that it is difficult to select appropriate loop-shaping weights, and the second is that the resulting controller is very complex. For the first drawback, Lanzon has proposed a suboptimal loop-shaping weight design method. It is formulated as a generalized eigenvalue minimization problem. This suboptimal loop-shaping weight design method provides high order weights, emphasizing the second drawback. To resolve these two drawbacks, a reduced-order loop-shaping weight and a stabilizing controller design methods are proposed in this paper. In the proposed method, the weight structure is first fixed, and the weight is decomposed into the frequency-dependent vector and the parameter matrices characterizing the loop-shaping weight. Since the open-loop constraints are represented as linear matrix inequalities with respect to the parameter matrices, the reduced-order loop-shaping weight design problem is formulated as a generalized eigenvalue minimization problem as well as the Lanzon’s suboptimal loop-shaping weight design method. Moreover, the stabilizing controller is first fixed to the initial stabilizing controller. The initial stabilizing controller is designed for the shaped plant obtained by the reduced-order weight design, by solving linear matrix inequalities. The proposed method can reduce the designer’s burden. The effectiveness of the proposed method is verified experimentally by the gain-scheduling control of a vertical-type inverted pendulum system.

상태 변환과 주파수응답특성을 응용한 Open-loop 제어 입력신호 생성과 반복 경로추종

김경수 육군사관학교 화랑대연구소 2019 한국군사학논집 Vol.75 No.3

Security operation requires repetitive tracking actions following a given path. The necessity of precise and repetitive tracking movement of the operational vehicle to follow a narrow and winding three-dimensional path has been increased in current operations. This paper introduces a precise tracking open-loop control technique that enables a system to move repetitive trajectory. The open-loop control input signal is generated by switching state to state transition input signal to steady-state repetitive tracking input signal. The simulation results for SISO system using switching input signals for the given path corresponding to the repetition rate of extreme, such as repetition rate over a bandwidth of the system, shows the efficacy of suggested techniques and possibility to use in military security purposes. 경계작전은 주어진 경로를 반복적으로 추종해야 하는 행동을 요구한다. 현대 작전에서 운용되는 차량이 좁고 구붉불한 3차원 경로를 정확하고 반복적으로 움직여야 하는 필요성은 점차 증가하고 있다. 본 논문은 반복 정밀 경로추종에 관한 Open-loop 제어 입력신호 생성에 관한 것이다. Open-loop 제어 입력신호는 정지상태에서 정상상태로 전환하는 상태변환 신호와 중상상태에서 반복적인 경로를 움직이는 신호로 구분하여 결합했다. 단순화된 SISO 시스템을 대상으로 주어진 반복적인 경로에 대한 추종 시뮬레이션결과를 제시했으며 시스템의 Bandwidth를 초과하는 반복속도에 대해 정밀 추종 성능과 군경계작전용 목적으로 활용하기에 충분한 효용성을 제시한다.

기체 탄화수소 연료 연소시험에서 연소불안정의 개루프 제어

황동현,안규복 한국추진공학회 2018 한국추진공학회지 Vol.22 No.6

기체 탄화수소 연료를 사용하는 덤프 연소기의 연소불안정에 개루프 제어를 적용하는 연구를 수행하였다. 연료들의 특성화학시간이 유사한 연소조건에서 음향 발생기를 이용하여 제어 출력과 주파수를 변화시켰다. 연소불안정 주파수와 동일한 주파수의 개루프 제어에서는 음향 발생기의 출력이 제어성능에 영향을 주었다. 연소불안정 주파수와 다른 주파수의 개루프 제어결과로부터 개루프 제어주파수는 연소불안정 주파수와 유사하게 설정하는 것이 효과적임을 알 수 있었다. A study was conducted to apply open-loop control to the combustion instability in a dump combustor using gaseous hydrocarbon fuels. Control power and frequency were varied by employing a loudspeaker under combustion conditions with similar characteristic chemistry times of the fuels. In the case of open-loop control where the frequency was identical to the combustion instability frequency, the open-loop control power affected the control performance. Results obtained from conducted open-loop control tests, where the frequency was different from the combustion instability frequency, show that setting the open-loop control frequency similar to the combustion instability frequency is effective.

Analytical design of an industrial two-term controller for optimal regulatory control of open-loop unstable processes under operational constraints

Tchamna, Rodrigue,Lee, Moonyong Elsevier 2018 ISA transactions Vol.72 No.-

<P><B>Abstract</B></P> <P>This paper proposes a novel optimization-based approach for the design of an industrial two-term proportional-integral (PI) controller for the optimal regulatory control of unstable processes subjected to three common operational constraints related to the process variable, manipulated variable and its rate of change. To derive analytical design relations, the constrained optimal control problem in the time domain was transformed into an unconstrained optimization problem in a new parameter space via an effective parameterization. The resulting optimal PI controller has been verified to yield optimal performance and stability of an open-loop unstable first-order process under operational constraints. The proposed analytical design method explicitly takes into account the operational constraints in the controller design stage and also provides useful insights into the optimal controller design. Practical procedures for designing optimal PI parameters and a feasible constraint set exclusive of complex optimization steps are also proposed. The proposed controller was compared with several other PI controllers to illustrate its performance. The robustness of the proposed controller against plant-model mismatch has also been investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optimal regulatory control of open-loop unstable process under operational constraints. </LI> <LI> An optimization based approach to find a global optimal solution of control system. </LI> <LI> The proposed method can handle operational constraints explicitly in controller design. </LI> <LI> The analytical design offers many useful insights to process control practitioners. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

개루프 제어 방식 이륜 로봇의 직진 및 선회 제어

정대규(Dae-Gyu Jeong),김진(Jin Kim) 한국정보기술학회 2015 Proceedings of KIIT Conference Vol.2015 No.6

이륜 로봇은 좌우 두 바퀴의 회전속도의 차이에 의해 조향이 이루어지는데 대부분의 실험용 저가 로봇의 경우 개루프 방식의 제어를 하고 있다. 그러므로 좌우 두 바퀴에 연결된 모터에 동일한 전압을 가하더라도 직진하기 어려운 문제가 있다. 본 논문에서는 이러한 개루프 제어 방식의 이륜 로봇에서 직진 및 선회 제어를 하는 방법에 대하여 다룬다. 먼저, 직진 제어를 위하여 전체 전압 구간에서 일정한 간격으로 직진할 수 있는 좌우 모터의 전압을 반복 실험으로 찾고, 각각의 전압에 대하여 직진 속도를 측정하였다. 그 후 측정된 직진 속도를 기반으로 하여 원하는 속도와 반경으로 선회하도록 하였다. 이 방법을 활용하면 개루프 방식의 제어를 하는 이륜 로봇의 제어에 많은 도움이 될 것으로 사료된다. Two-wheeled robots are steered by the difference of rotation speed between two wheels. And, most of laboratory cheap robots use open loop control system. Therefore, even if the two wheel motors are connected to the same voltage, we have the difficult problems to go straight. This paper deals with a method of the straight and turning control on two-wheeled robots in the open loop control system. First, find the voltage of the motor to the wheels straight by regular intervals in the entire voltage range for a straight control by repeated experiments. And then, We measured the velocity for each voltage. We made it to be desired turning speed and radius on the basis of the speed we have measured. By using this method, it is considered to be helpful in the control of two-wheeled robot control of open-loop manner.

Moving Horizon Optimal Control of Overhead Cranes

Yang, Hyun Suk 홍익대학교 과학기술연구소 2006 Hongik Journal of Science and Technology Vol.10 No.-

Optimal control method produces a best possible control input that minimizes or maximizes a pre-defined object function with some requirements. One drawback of this method is that when there are disturbances, unmodeled dynamics, or parameter variations, not only the control input produced by solving the optimal control problem is no longer an optimal solution but also the requirements may not be satisfied. Furthermore, when there is a significant error, it can not be fixed because optimal control method is an open-loop control method. Overheads crane, which are widely used in most industrial plants, are a system with unmodeled dynamics or disturbances such as winds and friction forces. In this paper, an time-energy optimal control law is proposed for overhead crane system. To deal with an error in state variables caused by disturbances or parameter variations, moving horizon control method is combined with the optimal control problem. The proposed control algorithm solves pre-defined time-energy optimal control problem continuously and updates the state variable to minimize any error occurred. To verify the superiority of this algorithm, simulation results are given. The results show that with moving horizon control method, the error of the state variables are reduced and all the requirements are satisfied.

유한 두께 창문 모델을 적용한 능동 소음제어 창문

권병호(Byoungho Kwon),박영진(Youngjin Park) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4

Active window system which can reduce the environmental noises, such as traffic noise and construction noise, from an open window into a room was proposed in the previous works. The key idea of the proposed active window system was that the control sources are approximately collocated with the primary noise source in terms of the acoustic power for global noise reduction throughout the interior room. Moreover, because it is important not to intrude into the living space in the building environment, no error sensors were used and an open-loop control method using control sources at the window frame and the reference sensors outside the room was used for the proposed system. The open-loop control gain was calculated by the interior room model assumed as the semi-infinite space, and the interior sound field was estimated by Rayleigh integral equation under the baffled window model assumption. However, windows with a finite thickness should were considered for the calculation of the open-loop control gain of the active window system since these are representative of most window cases. Therefore, the finite thickness window model based on the Sgard’s model was derived and the open-loop control gain using the interior sound field estimated by that model was calculated for active window system. To compare the performance of these two models, a scale-model experiment was performed in an anechoic chamber according to noise source directions. Experimental results showed that the performance for the thickness window model is better than the baffled window model as the angle with respect to the perpendicular direction is larger.

Design formulas for vibration control of taut cables using passive MR dampers

Yuanfeng Duan,Yi-Qing Ni,Hongmei Zhang,Billie. F., Jr. Spencer,Jan-Ming Ko,Yi Fang 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6

Using magnetorheological (MR) dampers in multiswitch open-loop control mode has been shown to be cost-effective for cable vibration mitigation. In this paper, a method for analyzing the damping performance of taut cables incorporating MR dampers in open-loop control mode is developed considering the effects of damping coefficient, damper stiffness, damper mass, and stiffness of the damper support. Making use of a three-element model of MR dampers and complex modal analysis, both numerical and asymptotic solutions are obtained. An analytical expression is obtained from the asymptotic solution to evaluate the equivalent damping ratio of the cable-damper system in the open-loop control mode. The individual and combined effects of the damping coefficient, damper stiffness, damper mass and stiffness of damper support on vibration control effectiveness are investigated in detail. The main thrust of the present study is to derive a general formula explicitly relating the normalized system damping ratio and the normalized damper parameters in consideration of all concerned effects, which can be easily used for the design of MR dampers to achieve optimal open-loop vibration control of taut cables.

Performance Comparison of Three Different Types of Attitude Control Systems of the Quad-Rotor UAV to Perform Flip Maneuver

이병윤,유동완,탁민제 한국항공우주학회 2013 International Journal of Aeronautical and Space Sc Vol.14 No.1

This paper addresses the performance of three different types of attitude control systems for the Quad-rotor UAV to perform the flip maneuver. For this purpose, Quad-rotor UAV’s 6-DOF dynamic model is derived, and it was used for designing an attitude controller of the Quad-rotor UAV. Attitude controllers are designed by three different methods. One is the open-loop control system design, another is the PD control system design, and the last method is the sliding mode control system design. Performances of all controllers are tested by 6-DOF simulation. In case of the open-loop control system, control inputs are calculated by the quad-rotor dynamic model and thrust system model that are identified by the thrust test. The 6-DOF realtime simulation environment was constructed in order to verify the performances of attitude controllers.

Filtered Velocity Feedback 제어기를 이용한 평판 능동진동제어

신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.10

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.