Control in Closed-loop System. Stability

2005 ◽  
pp. 259-297
Keyword(s):  
Closed Loop ◽  
Loop System ◽  
System Stability ◽  
Closed Loop System

scholarly journals Robust LFC Strategy for Wind Integrated Time-Delay Power System Using EID Compensation

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3223 ◽  
Author(s):  
Liu ◽  
Zhang ◽  
Zou
Keyword(s):  
Time Delay ◽  
Power System ◽  
Closed Loop ◽  
Frequency Control ◽  
Loop System ◽  
Load Frequency Control ◽  
System Stability ◽  
Linear Matrix ◽  
Closed Loop System ◽  
The Stability

This paper presents an active disturbance rejection control (ADRC) technique for load frequency control of a wind integrated power system when communication delays are considered. To improve the stability of frequency control, equivalent input disturbances (EID) compensation is used to eliminate the influence of the load variation. In wind integrated power systems, two area controllers are designed to guarantee the stability of the overall closed-loop system. First, a simplified frequency response model of the wind integrated time-delay power system was established. Then the state-space model of the closed-loop system was built by employing state observers. The system stability conditions and controller parameters can be solved by some linear matrix inequalities (LMIs) forms. Finally, the case studies were tested using MATLAB/SIMULINK software and the simulation results show its robustness and effectiveness to maintain power-system stability.

Robust attitude fault-tolerant control for unmanned autonomous helicopter with flapping dynamics and actuator faults

2018 ◽  
Vol 41 (5) ◽  
pp. 1266-1277 ◽  
Author(s):  
Kun Yan ◽  
Mou Chen ◽  
Qiangxian Wu ◽  
Ke Lu
Keyword(s):  
Closed Loop ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Loop System ◽  
System Stability ◽  
Actuator Faults ◽  
Closed Loop System ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Autonomous Helicopter

In this paper, an adaptive robust fault-tolerant control scheme is developed for attitude tracking control of a medium-scale unmanned autonomous helicopter with rotor flapping dynamics, external unknown disturbances and actuator faults. For the convenience of control design, the actuator dynamics with respect to the tail rotor are introduced. The adaptive fault observer and robust item are employed to observe the actuator faults and eliminate the effect of external disturbances, respectively. A backstepping-based robust fault-tolerant control scheme is designed with the aim of obtaining satisfactory tracking performance and closed-loop system stability is proved via Lyapunov analysis, which guarantees the convergence of all closed-loop system signals. Simulation results are given to show the effectiveness of the proposed control method.

scholarly journals High Efficient Solar Integrated an Isolated Dc-Dc Full-Bridge Converter for Electric Vehicle Battery Charging Application

2020 ◽  
Vol 9 (4) ◽  
pp. 432-437
Keyword(s):  
Electric Vehicle ◽  
Closed Loop ◽  
Open Loop ◽  
Loop System ◽  
System Stability ◽  
Control Technique ◽  
Closed Loop System ◽  
Conductance Method ◽  
High Efficient ◽  
Electric Vehicle Battery

In this paper, the power from a solar PV panel 20VDC, 12.5ADC is used for charging an electric vehicle battery (12V, 7Ah) with the help of an isolated dc-dc converter in an efficient manner. The power rating maintained in the system is around (200-250) W. The parasitic circuit analysis is carried out theoretically. The zero voltage transition (ZVT) technique is implemented at the inverter stage and an isolation transformer (1:1) is used for source-load isolation purposes. In order to achieve ZVT, a proper design procedure is followed and a pulse triggering technique is carried out at the switching element. The designed values of the parasitic elements are used in the Simulink tool. The open loop and closed loop system of the proposed converter are simulated in MATLAB Simulink package. In the open loop system, an irradiation analysis carried out similarly closed loop has reference voltage variation analysis in order to verify the system stability at the various operating condition. The problem of transients in open loop output is rectified in the closed loop operation. The MPP and PI control technique is initiated in the closed loop system for better performance. The MPP technique used is incremental conductance method for tracking maximum power from the PV array.

Multi Observer-Based Sliding Mode Load Frequency Control With Input Delay Estimation

2021 ◽  
Vol 1 (4) ◽  
Author(s):  
Ark Dev ◽  
David Fernando Novella Rodríguez ◽  
Sumant Anand ◽  
Mrinal Kanti Sarkar
Keyword(s):  
Power Systems ◽  
Closed Loop ◽  
Sliding Mode ◽  
Time Delay Estimation ◽  
Loop System ◽  
Load Frequency Control ◽  
System Stability ◽  
Input Delay ◽  
Delay Estimation ◽  
Closed Loop System

Abstract The letter proposes frequency stability in power systems with input delay. A closed loop system can be oscillatory or even unstable without the exact knowledge of delay. Therefore, it is desirable to design a control scheme which is based on the estimation of unknown delay. The proposed design consists of an infinite dimensional observer with an adaptive time delay estimation and a sliding mode controller (SMC). The merit of the proposed concept lies in the fact that the unknown delay is valued by just estimating the smallest delay segment. The controller input is obtained from a set of sequential observers that predicts the system states and ensures asymptotic stability of the closed loop system with input delay estimation. The existence of sliding mode and the closed loop system stability is proved thanks to the Lyapunov and Lyapunov–Krasovskii candidate functionals, respectively. Simulation results confirm the effectiveness of the proposed design.

Sensitivity Comparison to Loop Latencies Between Damping Versus Stiffness Feedback Control Action in Distributed Controllers

2014 ◽  
Author(s):  
Ye Zhao ◽  
Nicholas Paine ◽  
Luis Sentis
Keyword(s):  
Closed Loop ◽  
Impedance Control ◽  
Tracking Error ◽  
Loop System ◽  
Tracking Performance ◽  
System Stability ◽  
Step Response ◽  
Tracking Accuracy ◽  
Closed Loop System ◽  
And Performance

This paper studies the effects of damping and stiffness feedback loop latencies on closed-loop system stability and performance. Phase margin stability analysis, step response performance and tracking accuracy are respectively simulated for a rigid actuator with impedance control. Both system stability and tracking performance are more sensitive to damping feedback than stiffness feedback latencies. Several comparative tests are simulated and experimentally implemented on a real-world actuator to verify our conclusion. This discrepancy in sensitivity motivates the necessity of implementing embedded damping, in which damping feedback is implemented locally at the low level joint controller. A direct benefit of this distributed impedance control strategy is the enhancement of closed-loop system stability. Using this strategy, feedback effort and thus closed-loop actuator impedance may be increased beyond the levels possible for a monolithic impedance controller. High impedance is desirable to minimize tracking error in the presence of disturbances. Specially, trajectory tracking accuracy is tested by a fast swing and a slow stance motion of a knee joint emulating NASA-JSC’s Valkyrie legged robot. When damping latencies are lowered beyond stiffness latencies, gravitational disturbance is rejected, thus demonstrating the accurate tracking performance enabled by a distributed impedance controller.

A Robustly Stable Multiestimation-Based Adaptive Control Scheme for Robotic Manipulators

2005 ◽  
Vol 128 (2) ◽  
pp. 414-421 ◽  
Author(s):  
A. Ibeas ◽  
M. de la Sen
Keyword(s):  
Adaptive Systems ◽  
Closed Loop ◽  
Sudden Change ◽  
Robotic Manipulators ◽  
Adaptive Controller ◽  
Time Instant ◽  
Loop System ◽  
System Stability ◽  
Closed Loop System ◽  
Control Scheme

A multiestimation-based robust adaptive controller is designed for robotic manipulators. The control scheme is composed of a set of estimation algorithms running in parallel along with a supervisory index proposed with the aim of evaluating the identification performance of each one. Then, a higher-order level supervision algorithm decides in real time the estimator that will parametrize the adaptive controller at each time instant according to the values of the above supervisory indexes. There exists a minimum residence time between switches in such a way that the closed-loop system stability is guaranteed. It is verified through simulations that multiestimation-based schemes can improve the transient response of adaptive systems as well as the closed-loop behavior when a sudden change in the parameters or in the reference input occurs by appropriate switching between the various estimation schemes running in parallel. The closed-loop system is proved to be robustly stable under the influence of uncertainties due to a poor modeling of the robotic manipulator. Finally, the usefulness of the proposed scheme is highlighted by some simulation examples.

Frequency-Domain Vibration Control of Distributed Gyroscopic Systems

1991 ◽  
Vol 113 (1) ◽  
pp. 18-25 ◽  
Author(s):  
B. Yang ◽  
C. D. Mote
Keyword(s):  
Vibration Control ◽  
Closed Loop ◽  
Loop System ◽  
System Stability ◽  
Root Locus ◽  
Closed Loop System ◽  
Locus Method ◽  
Nyquist Criterion ◽  
Actuation Devices ◽  
Gyroscopic Systems

A new method is presented for vibration control of distributed gyroscopic systems. The control is formulated in the Laplace transform domain. The transfer function of a closed-loop system, consisting of the plant, a feedback control law and the dynamics of the sensing and actuation devices, is derived. Stability analyses of the closed-loop system use both the root locus method and the generalized Nyquist criterion. Two stability criteria are obtained. Design of stabilizing controllers is carried out for both colocation and noncolocation of the sensor and actuator. The effects of time-delay and noncolocation of the sensor and actuator on the system stability are analyzed. In addition, the relationship between the root locus method and the generalized Nyquist criterion is discussed.

scholarly journals Boundary Conditions for Transient and Robust Performance of a Reduced-Order Model-Based State Feedback Controller with PI Observer

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2881
Author(s):  
Nebiyeleul Daniel Amare ◽  
Doe Hun Kim ◽  
Sun Jick Yang ◽  
Young Ik Son
Keyword(s):  
State Feedback ◽  
Closed Loop ◽  
Loop System ◽  
Reduced Order Model ◽  
System Stability ◽  
Order System ◽  
Closed Loop System ◽  
Order Model ◽  
Reduced Order ◽  
Model Based

One common technique employed in control system design to minimize system model complexity is model order reduction. However, controllers designed by using a reduced-order model have the potential to cause the closed-loop system to become unstable when applied to the original full-order system. Additionally, system performance improvement techniques such as disturbance observers produce unpredictable outcomes when augmented with reduced-order model-based controllers. In particular, the closed-loop system stability is compromised when a large value of observer gain is employed. In this paper, a boundary condition for the controller and observer design parameters in which the closed-loop system stability is maintained is proposed for a reduced-order proportional-integral observer compensated reduced-order model-based controller. The boundary condition was obtained by performing the stability analysis of the closed-loop system using the root locus method and the Routh-Hurwitz criterion. Both the observer and the state feedback controller were designed using a reduced-order system model based on the singular perturbation theory. The result of the theoretical analysis is validated through computer simulations using a DC (direct current) motor position control problem.

Vibration Control of Rotor Systems With Noncollocated Sensor/Actuator by Experimental Design

1995 ◽  
Author(s):  
S. M. Yang ◽  
G. J. Sheu ◽  
C. D. Yang
Keyword(s):  
Experimental Design ◽  
Closed Loop ◽  
Loop System ◽  
System Stability ◽  
Control Technique ◽  
Design Parameters ◽  
Closed Loop System ◽  
Rotor Systems ◽  
Sensor Actuator ◽  
Operation Speed

Abstract This paper presents a controller design methodology for vibration suppression of rotor systems in noncollocated sensor/actuator configuration. The methodology combines the experimental design method of quality engineering and the active damping control technique such that their advantages in implementation feasibility and performance-robustness can be integrated together. Compared with LQ-based design, the controller order is smaller and it is applicable to systems in an operation speed range. In addition, neither preselected sensor/actuator location nor state measurement/estimation is needed. By using the locations of sensor/actuator and the feedback gains as design parameters, the controller is shown to achieve the best possible system performance while maintaining the closed loop system stability. Analyses also show that, contrary to common believe, the performance of a closed loop system with noncollocated sensor/actuator can be superior to that with a collocated one.

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