Feedback Controller Design Method Research Articles

Fuzzy control for networked systems with mixed data missing under quantization based event-triggered scheme

This paper presents an innovative event-triggered fuzzy control approach for networked systems operating over unreliable network channels. Traditional complicated modeling and analysis process of network induced issues is replaced by a bran-new logarithmic quantization based event-triggered scheme method. The joint characterization of mixed data missing, arising from the event-triggered mechanism and unreliable network channels, becomes a challenging issue due to disrupted data sequences and variable relations. Consequently, this paper contributes a formulated auxiliary stochastic sequence approach to overcome the difficulty of dynamics modeling. With an formulated event driven controller, the modeling and implementation of the closed-loop systems are constructed and further simplified. Considering the difference and relation between the membership functions of plant and controller, we present a new fuzzy output feedback controller design method to obtain feasible result via uncertainty based method. Finally, we verify the validity of the designed control policy via a simulation example.

Event‐triggered output feedback H∞$$ H\infty $$ control for Markovian jump networked control systems with signal quantization

AbstractThis article studies the output feedback control problem for event‐triggered Markovian jump networked control systems with signal quantization. First, a Lyapunov–Krasovskii function is constructed, which contains time delay, upper bound of time delay and conditional transition probability information of Markovian jump systems. Second, when using the Wirtinger's inequality and the Reciprocally convex inequality to estimate the upper bound of the delay of the weak infinitesimal generator operator of the Lyapunov–Krasovskii function, the event‐triggered scheme and the signal quantization scheme are introduced. Finally, the stability criterion of the closed‐loop system of event‐triggered Markovian jump networked control systems and the design method of the output feedback controller of disturbance attenuation level are given in the form of linear matrix inequalities (LMIs). The effectiveness of the proposed method is verified by two numerical examples.

Observer‐based fault tolerant control for a class of nonlinear multi‐agent systems with sensor faults

AbstractThis article focuses on the robust fault tolerant control (FTC) problem for a class of Lipschitz nonlinear multi‐agent systems(MASs) subject to sensor faults. Firstly, sensor faults are transformed into actuator faults via introducing a new intermediate auxiliary state variable, and a distributed adaptive fault estimation observer is designed to estimate the state information and the concerned faults by using the relative output estimation error. Then, the sufficient existence conditions for the observer to satisfy the robust performance index are given. Thirdly, based on the results of observer design, a new design method of dynamic output feedback controller is proposed to implement consensus of MASs and ensure the desired disturbance rejection performance. Finally, the simulation results are presented to illustrate the effectiveness of the proposed method.

Dynamic optimal control of flow front position in injection molding process: A control parameterization-based method

High dynamic and precise control of process variables within permissible limits is the key to high product quality in the injection molding industry. Among these variables, the injection flow rate of molten polymer is particularly significant. In this paper, an effective optimal open-loop and state feedback controller design method is designed to realize the optimal tracking control of the melt polymer flow front position flow of melt polymer fluid during injection molding. To this end, the dynamic model of the filling process is firstly established, taking into account the nonlinearity of hydraulic control system and the effect of molten polymer flow on the dynamics of the injection ram, and then the dynamic optimal tracking control problem of flow front position of molten polymer in injection molding machine is proposed. Then, an open-loop controller and a multi-level feedback control law are well designed, wherein the control signal and the control feedback kernels are parameterized by control parameterization. The controller design problems are transformed into sequential optimal parameter decision problems. The explicit expressions of the gradient information of the objective function and constraints on the parameters of the decision variables are solved by using the state sensitivity equation analysis method, and the gradient information is combined with the nonlinear programming algorithm to solve the optimization problems efficiently. Finally, the viability and effectiveness of the proposed design method are verified by numerical simulations.

Adaptive optimal output regulation of unknown linear continuous-time systems by dynamic output feedback and value iteration

This paper proposes a value iteration based learning algorithm to solve the optimal output regulation problem for linear continuous-time systems, which aims at achieving disturbance rejection and asymptotic tracking simultaneously. Notably, the state is unmeasurable and the system dynamics is completely unknown, which greatly increases the challenge of solving the output regulation problem. Firstly, we present a dynamic output feedback controller design method by combining the internal model, setting a virtual exo-system, and constructing the augmented internal state without using any knowledge of system. Then, by establishing a novel iterative learning equation which requires no repeated finite window integral operations, an adaptive dynamic programming based learning algorithm with employing value-iteration scheme is proposed to estimate the optimal feedback control gain, which may lead to a reduction of the computational load. The analysis on solvability and convergence shows that the estimated control gain converges to the optimal control gain. Finally, a physical experiment on control of an unmanned quadrotor illustrates the effectiveness of the proposed algorithm.

Leader–follower output consensus of multiagent systems over finite fields

This paper studies the output consensus problem of leader–follower multiagent systems (MASs) over finite fields via semi-tensor product (STP). First, the leader–follower MASs over finite fields are modeled as algebraic form, based on which, the output consensus problem is transformed into the set stabilization problem about the systems with algebraic form. Second, all the output feedback control invariant sets (OFCISs) are calculated from the state feedback maximum control invariant set (SFMCIS). Third, some criteria of the output consensus as well as the design method of output feedback controller are presented by the truth matrix technique. Finally, an example is shown to demonstrate the effectiveness of the results.

Attitude and Altitude Control Design and Implementation of Quadrotor Using NI myRIO

Multi-rotor vehicles have demonstrated great potential in many applications, from goods delivery to military service. Its simple structure has drawn much attention in control research, with various feedback control design methods being tested on it. In this study, a quadrotor is constructed with National Instrument (NI) myRIO for its flight controller. Linear controllers are synthesized with a simple model and with a more detailed model, which also considers the actuator dynamic and system time delay, to exploit the limitations and trade-offs posted by hardware and its influence on linear control design and implementation. The simulation results match the real response better if the detailed model is used in the control design. In addition, the linear–quadratic–Gaussian (LQG) control provides the best response in the control design in this study. The constraints posted by the actuator and time delay are clearly observed in the control synthesis process and the experiment result. These constraints also led to poor control performance or even instability if not considered in the control implementation in advance.

Dynamic Event-Triggered Output Feedback Control for Networked Systems Subject to Multiple Cyber Attacks.

This article is concerned with the problem of the H∞ output feedback control for a class of event-triggered networked systems subject to multiple cyber attacks. Two dynamic event-triggered generators are equipped at sensor and observer sides, respectively, to lower the frequency of unnecessary data transmission. The sensor-to-observer (STO) channel and observer-to-controller (OTC) channel are subject to deception attacks and Denial-of-Service (DoS) attacks, respectively. The aim of the addressed problem is to design an output feedback controller, with the consideration of the effects of dynamic event-triggered schemes (DETSs) and multiple cyber attacks. Sufficient condition is derived, which can guarantee that the resulted closed-loop system is asymptotically mean-square stable (AMSS) with a prescribed H∞ performance. Moreover, we provide the desired output feedback controller design method. Finally, the effectiveness of the proposed method is demonstrated by an example.

Design Method of the Wheel Slip Speed Feedback Controller and Phase Lead Compensator in Locomotives

Design Method of the Wheel Slip Speed Feedback Controller and Phase Lead Compensator in Locomotives

Guaranteed cost robust output feedback control design for fractional-order uncertain neutral delay systems

This paper investigates the stabilization of uncertain neutral-type delay fractional systems. Both static and dynamic output feedback control design methods are proposed. A guaranteed cost-based feedback control design is considered and closed-loop robust stability is investigated using the Lyapunov theorem. Asymptotic stability conditions of the closed-loop system is described in terms of linear matrix inequalities (LMIs). A simulation study, encompassing a numerical example of a fractional order system and a two stage chemical reactor, is considered to assess the performance and validity of the proposed control design.

Dynamics, stability, and control of a four-cable mount system for wind tunnel test

A four-cable mount system is proposed for full-model wind tunnel flutter tests, which may adjust the pitch and roll attitude of the aircraft scaled model and ensure that the model is not subjected to cable tension. The system provides sufficient support to simulate the free flight of the aircraft by applying appropriate spring stiffness and cable tensions. The proposed four-cable mount system is modeled based on Lagrange mechanics, and its dynamics equations consider aerodynamic effects. The singularity of the system and its bifurcation characteristics under flow conditions are analysed to determine the supercritical bifurcation phenomenon for different tension levels and distances from the front suspension point to the mass centre of the model. The mathematical expressions of the longitudinal flight stability of the cable mount system are derived by linearising the system dynamics equations using small perturbations. The influence of the cable tension, spring stiffness, suspension point position, and other factors on the flight stability of the aircraft are analysed. A feedforward control algorithm is proposed to minimize the total elastic potential energy of the system. The results show that the model is in the level flight state when the elastic potential energy of the four-cable mount system is minimized. A feedback control design method is proposed based on the Lyapunov stability theory to derive the closed-loop stability conditions. The system dynamics model that includes the aircraft rigid body model, flexible cables, pulleys, springs, aerodynamic model, and servo motor control is established using the flexible multibody dynamics method. A multibody dynamics solver and Simulink are used to simulate the attitude adjustment of the model in the wind tunnel and verify the supercritical bifurcation characteristics of the system and the effectiveness of the feedback and feedforward control.

Handshake Logic-Based Event-Triggered Load Frequency Control for Smart Grids Under DoS Attacks

This paper investigates the load frequency control (LFC) problem for smart grids with denial-of-service (DoS) attacks via a novel event-triggered control method. In order to sustain the stable operation of the smart grids, a handshake logic-based event-triggered communication scheme (HLETCS) is proposed. The targets of the designed controller are twofold. Firstly, an event-triggered mechanism with a handshake logic-based concept is proposed to save network resources. In this triggering method, a handshake protocol is used to detect DoS attacks in the communication networks. Secondly, through employing Lyapunov stability theory, sufficient stabilization criteria ensuring the uncertain LFC systems being asymptotically stable are deduced. Based on these conditions, the corresponding state feedback controller design method is given. Finally, a simulation of a two-area power system with electric vehicles is given as an example to substantiate the proposed method of this paper.

Fuzzy dynamic output feedback control for nonlinear networked multirate sampled-data systems: An integral inequality method

This paper is devoted to fuzzy dynamic output feedback control for nonlinear networked multirate sampled-data systems based on T-S fuzzy systems. Using asynchronous multirate sampled-data, a multirate fuzzy controller is designed. The resultant closed-loop system is modeled as a perturbed system with two perturbed terms which include multirate sampling and the asynchronous membership functions between the controlled plant and the controller. A novel refined integral inequality is developed, and it improves Jensen's inequality and extends Wirtinger's inequalities by considering the sawtooth structure of time-varying delays. By applying the inequality to the perturbed system and constructing a new storage function, a stability criterion and two fuzzy dynamic output feedback controller design methods are presented for the nonlinear networked multirate sampled-data systems. Finally, three illustrative examples show the effectiveness of the proposed method.

H∞ controller design for singular Markov jump systems with time-delays

In this article, the [Formula: see text] control problem of a class of singular Markov jump systems with time-varying inputs and state delays is investigated. Based on the Lyapunov stability theory, by constructing a different Lyapunov–Krasovskii functional, the sufficient conditions of being stochastic stable and having H∞ performance index are given. Then, the design method of state feedback controller is given to ensure the closed-loop system is stochastic stable and has [Formula: see text] performance index. Finally, simulation examples are given to verify the effectiveness of the proposed methods.

Finite-Time Control of Singular Linear Semi-Markov Jump Systems

The problem of finite-time control for singular linear semi-Markov jump systems (SMJSs) with unknown transition rates is considered in this paper. By designing a new semi-positive definite Lyapunov-like function, state feedback controller design methods are given that allow closed-loop singular linear SMJSs to be regular, impulse-free and stochastically finite-time-stable without external disturbance, and stochastically finite-time bounded with external disturbance. The obtained conditions are expressed by a set of strict matrix inequalities, which can be simplified to a set of linear matrix inequalities by a one dimensional search for a scalar. Two numerical examples are given to illustrate the effectiveness of proposed method.

반복적인 선형행렬부등식을 이용한 연속시간 T-S 퍼지 시스템에 대한 정적 출력궤환 제어

This investigation deals with the design method of a static output feedback controller for continuous-time T-S fuzzy systems via iterative linear matrix inequalities. First, a matrix inequality that guarantees the stability of the nonlinear system is introduced. Based on this, an algorithm for finding the stabilization control gains, using the cone complementary linearization method, for continuous-time T-S fuzzy systems is presented. The validity of the proposed algorithm is verified through a simple example.

Neuro‐adaptive output‐feedback optimized stochastic control for the active suspension systems with state constraints

SummaryThis article investigates an adaptive neural network (NN) output‐feedback optimal control design problem for active suspension systems (ASSs) with stochastic disturbance. The ASSs under consideration contain the characteristics of spring nonlinear dynamics, unmeasured states, and state constraints. The NNs are developed to approximate the unknown nonlinear functions. Meanwhile, observer‐based output feedback control design method is proposed based on the adaptive backstepping technique. Furthermore, the stability of the closed‐loop system is demonstrated by constructing the barrier Lyapunov function, thus ensuring that the full‐state constraints are not exceeded. In particular, the simulation validations are given for the cases of bump, C‐class, and D‐class road displacements inputs. Finally, the simulation results verify the effectiveness of the studied control strategy.

Dynamic output feedback control for networked systems with limited communication based on deadband event-triggered mechanism

In this paper, a deadband event-triggered mechanism is used to reduce the transmission data of the network channel to improve the performance of networked control systems (NCSs) with limited communication. In view of the unmeasurable state signal in the actual network system, the dynamic output feedback control problem for the NCSs is studied. When network-induced delays, time-varying sampling intervals and signal transmission deadbands are considered simultaneously, the model of NCSs under the deadband event-triggered mechanism is constructed, and a sufficient condition for the stability of NCSs is given. Furthermore, the design method of the dynamic output feedback controller of NCSs under deadband event-triggered mechanism is proposed. Two simulation examples are used to show that the proposed approach can obtain the dynamic output feedback controller for NCSs with the deadband event-triggered mechanism, and also illustrate the deadband event-triggered mechanism can reduce the signal transmission in the network channel to obtain better system performance.

Stability and control of fuzzy time delay systems with unmatched preconditions

The stability and control of nonlinear time-delay systems of Takagi-Sugeno (T-S) fuzzy model are studied in this paper. The integral inequality of a free weight matrix is chosen to give a less conservative delay-dependent stability criterion in the form of linear matrix inequalities (LMIs). The premise mismatch strategy is applied, it is combined with Finsler lemma, a more flexible design method of fuzzy state feedback controller is proposed. This method does not require the controller and system to share the common premise membership function and the number of rules. The controller design strategy proposed in this paper can effectively solve the control problem of fuzzy systems when the number of state variables is not equal to the number of input variables (r≠c), or mi⁢(x⁢(t))≠hi⁢(x⁢(t)),i=1,2,…,r. Finally, two simulation examples are given to prove the advancement and effectiveness of the proposed theory.

이산시간 불확실 특이시스템의 새로운 강인 유한시간 상태궤환 제어

In this paper, we consider the problem of robust finite-time singular stability(RFSS) and state feedback controller design method for discrete–time linear singular systems with norm-bounded parameter uncertainties. First, the FSS sufficient condition is derived by equivalently transformed closed-loop system. Second, a state feedback controller design method satisfying regular, causal, and RFSS is proposed by LMI(linear matrix inequality) technique on the basis of the obtained FSS condition and equivalent properties of the considering system. The presented conditions are strict LMI conditions in terms of finding all variables compared with previous results. Finally, a numerical example is given to illustrate the validity of the proposed method.