Existing control algorithms for seismic shake table tests (STTs) generally exhibit limitations such as poor acceleration tracking for displacement control, instability that results in table drift for ...direct acceleration, force, or velocity control, and the lack of a theoretical justification for hybrid control. Therefore, a reliable control algorithm has become key for effective shake table control. This paper presents acceleration‐based sliding mode control (SMC) as a solution to the drawbacks of the traditional force‐based SMC; in this manner, the influence of the force of the tested structure applied on the table as well as unmodeled complex nonlinear forces, such as friction, are counteracted. An acceleration‐based sliding mode hierarchical control (ASMHC) algorithm is proposed, where the acceleration‐based SMC is used as the high‐level controller to generate the corrected acceleration command, and the low‐level controller, that includes feed‐forward and feedback control, tracks the acceleration command in real time. The high‐level controller, having zero asymptotic stability, and the low‐level controller, designed based on the system transfer function, ensure tracking stability in time and frequency domains, respectively. The proposed ASMHC algorithm was first verified by a series of bare STTs, and was then applied to a real STT of a two‐story steel structure. The experimental results show that the proposed ASMHC algorithm can achieve good tracking of displacement, velocity, and acceleration in both time and frequency domains, which ensures accurate reproduction of seismic excitation in STTs.
Distributed cooperative control has been used as a preferred secondary control strategy for maintaining frequency synchronization and voltage restoration in cyber-physical AC microgrids due to its ...flexibility, scalability and better computational performance. However, such a control system is susceptible to potential cyber attacks, i.e., false data injection (FDI) attacks. To this end, this article introduces a hidden layer based attack-resilient distributed cooperative control algorithm to solve the problem of the secondary control of islanded microgrids under FDI attacks. In comparison to the existing attack-resilient distributed control methods, the proposed controller with sufficient large <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula> can mitigate the adverse effects of time dependent FDI attacks on actuators, sensors and communication links of the control system, and is also robust to state dependent FDI attacks. Furthermore, the algorithm is applicable even when all DGs and communications are compromised. Finally, the efficiency of the proposed controller is evaluated for a test microgrid with 4 DGs under different types of attack.
In the process industries, stiction is the most common performance-limiting valve problem and over the last decade numerous different techniques for overcoming it have been proposed.This book ...represents a comprehensive presentation of these methods, including their principles, assumptions, strengths and drawbacks. Guidelines and working procedures are provided for the implementation of each method and MATLAB®-based software can be downloaded from www.ualberta.ca/~bhuang/stiction-book enabling readers to apply the methods to their own data. Methods for the limitation of stiction effects are proposed within the general context of: oscillation detection in control loops, stiction detection, diagnosis and stiction quantification and diagnosis of multiple faults.The state-of-the-art algorithms presented in this book are demonstrated and compared in industrial case studies of diverse origin - chemicals, building, mining, pulp and paper, mineral and metal processing.
An adaptive control algorithm for open-loop stable, constrained, linear, multiple input multiple output systems is presented. The proposed approach can deal with both input and output constraints, as ...well as measurement noise and output disturbances. The adaptive controller consists of an iterative set membership identification algorithm, that provides a set of candidate plant models at each time step, and a model predictive controller, that enforces input and output constraints for all the plants inside the model set. The algorithm relies only on the solution of standard convex optimization problems that are guaranteed to be recursively feasible. The experimental results obtained by applying the proposed controller to a quad-tank testbed are presented.
In this article, the problem of optimal time-varying attitude tracking control for rigid spacecraft with system constraints and unknown additive disturbances is considered. Through the design of a ...new nonlinear tube-based robust model predictive control (TRMPC) algorithm, a dual-loop cascaded tracking control framework is established. The proposed TRMPC algorithm explicitly considers the effect of disturbances and applies tightened system constraints to predict the motion of the nominal system. The obtained optimal control action is then combined with a nonlinear feedback law such that the actual system trajectories can always be steered within a tube region centered around the nominal solution. To facilitate the recursive feasibility of the optimization process and guarantee the input-to-state stability of the tracking control process, the terminal controller and the corresponding terminal invariant set are also constructed. The effectiveness of using the proposed dual-loop TRMPC control scheme to track reference attitude trajectories is validated by experimental studies. A number of comparative studies were carried out, and the obtained results reveal that the proposed design is able to achieve more promising constraint handling and attitude tracking performance than that of the other newly developed methods investigated in this research.
Power electronics technology is still an emerging technology, and it has found its way into many applications, from renewable energy generation (i.e., wind power and solar power) to electrical ...vehicles (EVs), biomedical devices, and small appliances, such as laptop chargers. In the near future, electrical energy will be provided and handled by power electronics and consumed through power electronics; this not only will intensify the role of power electronics technology in power conversion processes, but also implies that power systems are undergoing a paradigm shift, from centralized distribution to distributed generation. Today, more than 1000 GW of renewable energy generation sources (photovoltaic (PV) and wind) have been installed, all of which are handled by power electronics technology. The main aim of this book is to highlight and address recent breakthroughs in the range of emerging applications in power electronics and in harmonic and electromagnetic interference (EMI) issues at device and system levels as discussed in ?robust and reliable power electronics technologies, including fault prognosis and diagnosis technique stability of grid-connected converters and ?smart control of power electronics in devices, microgrids, and at system levels.
Power electronics technology is still an emerging technology, and it has found its way into many applications, from renewable energy generation (i.e., wind power and solar power) to electrical ...vehicles (EVs), biomedical devices, and small appliances, such as laptop chargers. In the near future, electrical energy will be provided and handled by power electronics and consumed through power electronics; this not only will intensify the role of power electronics technology in power conversion processes, but also implies that power systems are undergoing a paradigm shift, from centralized distribution to distributed generation. Today, more than 1000 GW of renewable energy generation sources (photovoltaic (PV) and wind) have been installed, all of which are handled by power electronics technology. The main aim of this book is to highlight and address recent breakthroughs in the range of emerging applications in power electronics and in harmonic and electromagnetic interference (EMI) issues at device and system levels as discussed in ?robust and reliable power electronics technologies, including fault prognosis and diagnosis technique stability of grid-connected converters and ?smart control of power electronics in devices, microgrids, and at system levels.
The problem of adaptive fuzzy decentralized fault-tolerant optimal control is investigated for nonlinear large-scale systems with actuator faults in this paper. Fuzzy logic systems are utilized to ...approximate the unknown nonlinear functions and learn cost functions. Filtered signals are adopted to circumvent the problems of an algebraic loop on designing the decentralized controllers. Based on the backstepping technique and fault-tolerant control technique, a decentralized feedforward control strategy is designed. Based on the adaptive critic technique, a decentralized feedback optimal control strategy is designed. By combining the feedforward control strategy with the feedback optimal control strategy, a novel adaptive fuzzy decentralized fault-tolerant optimal control scheme is established. The stability of the closed-loop system is proved by using the Lyapunov stability theory. The effectiveness of the proposed decentralized control approach is confirmed via a simulation example.
Shunt active power filters have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. This paper presents an all-digital approach based ...on a particular repetitive control technique for their control. Specifically, a digital repetitive plug-in controller for odd-harmonic discrete-time periodic references and disturbances is used for the current control loops of the active filter. This approach does not introduce a high gain at those frequencies for which it is not needed and, thus, improves robustness of the controlled system. The active power balance of the whole system is assured by an outer control loop, which is designed from an energy-balancing perspective. The design is performed for a three-phase four-wire shunt active filter with a full-bridge boost topology. Several experimental results are also presented to show the good behavior of the closed-loop system
In this paper, an adaptive trajectory tracking control algorithm for underactuated unmanned surface vessels (USVs) with guaranteed transient performance is proposed. To meet the realistic dynamical ...model of USVs, we consider that the mass and damping matrices are not diagonal and the input saturation problem. Neural networks (NNs) are employed to approximate the unknown external disturbances and uncertain hydrodynamics of USVs. Moreover, both full-state feedback control and output feedback control are presented, and the unmeasurable velocities of the output feedback controller are estimated via high-gain observer. Unlike the conventional control methods, we employ the error transformation function to guarantee the transient tracking performance. Both simulation and experimental results are carried out to validate the superior performance via comparing with traditional potential integral control approaches.
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