Dynamic output feedback stabilization of deterministic finite automata via the semi‑tensor product of matrices approach

This paper deals with the dynamic output feedback stabilization problem of deterministic finite automata (DFA). The static form of this problem is defined and solved in previous studies via a set of equivalent conditions. In this paper, the dynamic output feedback (DOF) stabilization of DFAs is defined in which the controller is supposed to be another DFA. The DFA controller will be designed to stabilize the equilibrium point of the main DFA through a set of proposed equivalent conditions. It has been proven that the design problem of DOF stabilization is more feasible than the static output feedback (SOF) stabilization. Three simulation examples are provided to illustrate the results of this paper in more details. The first example considers an instance DFA and develops SOF and DOF controllers for it. The example explains the concepts of the DOF controller and how it will be implemented in the closed-loop DFA. In the second example, a special DFA is provided in which the DOF stabilization is feasible, whereas the SOF stabilization is not. The final example compares the feasibility performance of the SOF and DOF stabilizations through applying them to one hundred random-generated DFAs. The results reveal the superiority of the DOF stabilization.     

Control of nonholonomic systems with nonlinear unmeasured dynamics by output feedback

This paper studies the problem of output feedback stabilization for a class of more general nonholonomic systems whose nonlinear drifts are polynomially bounded by high-order terms of unmeasured states. An output feedback controller is obtained applying the backstepping approach and the dual observer method. The homogenous theory is also utilized in the recursive process. Together with a switching control scheme, the designed controller guarantees that the closed-loop system is output feedback globally asymptotically stabilized and the states converge to zero asymptotically. A simulation example is provided to illustrate the validness of the proposed approach.     

Output feedback stabilization of switched stochastic nonlinear systems under arbitrary switchings

This paper is concerned with the problem of global output feedback stabilization in probability for a class of switched stochastic nonlinear systems under arbitrary switchings. The subsystems are assumed to be in output feedback form and driven by white noise. By introducing a common Lyapunov function, the common output feedback controller independent of switching signals is constructed based on the backstepping approach. It is proved that the zero solution of the closed-loop system is fourth-moment exponentially stable. An example is given to show the effectiveness of the proposed method.     

Output feedback control of networked systems

This paper considers the problem of control of networked systems via output feedback. The controller consists of two parts: a state observer that estimates plant state from the output when it is available via the communication network, and a model of the plant that is used to generate a control signal when the plant output is not available from the network. Necessary and sufficient conditions for the exponential stability of the closed loop system are derived in terms of the networked dwell time and the system parameters. The results suggest simple procedures for designing the output feedback controller proposed. Numerical simulations show the feasibility and efficiency of the proposed methods.     

Dynamic consensus of high-order multi-agent systems and its application in the motion control of multiple mobile robots

In this paper, the leader-following consensus problem for multi-agent linear dynamic systems is considered. All agents and leader have identical multi-input multi-output (MIMO) linear dynamics that can be of any order, and only the output information of each agent is delivered throughout the communication network. When the interaction topology is fixed, the leader-following consensus is attained by H∞ dynamic output feedback control, and the sufficient condition of robust controllers is equal to the solvability of linear matrix inequality (LMI). The whole analysis is based on spectral decomposition and an equivalent decoupled structure achieved, and the stability of the system is proved. Finally, we extended the theoretical results to the case that the interaction topology is switching. The simulation results for multiple mobile robots show the effectiveness of the devised methods.     

Global output feedback control of feedforward nonlinear time-delay systems with unknown growth rate and unknown measurement sensitivity

This paper discusses the problem of global state regulation via output feedback for a class of feedforward nonlinear time-delay systems with unknown measurement sensitivity. Different from previous works, the nonlinear terms are dominated by upper triangular linear unmeasured (delayed) states multiplied by unknown growth rate. The unknown growth rate is composed of an unknown constant, a power function of output, and an input function. Furthermore, due to the measurement uncertainty of the system output, it is more difficult to solve this problem. It is proved that the presented output feedback controller can globally regulate all states of the nonlinear systems using the dynamic gain scaling technique and choosing the appropriate Lyapunov–Krasovskii functionals.     

A unified approach to output synchronization of heterogeneous multi-agent systems via L2-gain design

In this paper, a unified design procedure is given for output synchronization of heterogeneous multi-agent systems (MAS) on communication graph topologies, using relative output measurements from neighbors. Three different control protocols, namely, full-state feedback, static output-feedback, and dynamic output-feedback, are designed for output synchronization. It is seen that a unified design procedure for heterogeneous MAS can be given by formulation and solution of a suitable local $\mathcal{L}{_2}$-gain design problem. Sufficient conditions are developed in terms of stabilizing the local agents'' dynamics, satisfying a certain small-gain criterion, and solving the output regulator equations. Local design procedures are presented for each agent to guarantee that these sufficient conditions are satisfied. The proposed control protocols require only one copy of the leader''s dynamics in the compensator, regardless of the dimensions of the outputs. This results in lower-dimensional compensators for systems with high-order outputs, compared to the $p$-copy internal model approach. All three proposed control protocols are verified using numerical simulations.     

Nonlinear inversion-based output tracking control of a boiler-turbine unit

The capability to perform fast load_following has been an important issue in the power industry. An output tracking control system of a boiler_turbine unit is developed. The system is composed of stable inversion and feedback controller. The stable inversion is implemented as a feedforward controller to improve the load_following capability, and the feedback controller is utilized to guarantee the stability and robustness of the whole system. Loop_shaping H_∞ method is used to design the feedback controller and the final controller is reduced to a multivariable PI form. The output tracking control system takes account of the multivariable, nonlinear and coupling behavior of boiler_turbine system, and the simulation tests show that the control system works well and can be widely applied.     

离散时间系统量化动态输出反馈的H∞控制

The problem of quantized dynamic output feedback H_∞control for discrete-time linear time-invariant(LTI)systems is investigated in this paper.The quantizer considered is dynamic and composed of an adjustable"zoom"parameter and a static quantizer.Static quantizer ranges are of practical significance and are fully considered.First,taking quantization errors into account, a quantized control strategy is dependent not only on the controller states but also on the system measurement outputs,which is proposed such that the quantized closed-loop system is asymptotically stable and with a prescribed H_∞performance bound.Then, on the basis of this result,an iterative LMI-based optimization algorithm is developed to optimize the static quantizer ranges to meet H_∞performance requirements for closed-loop systems.An example is presented to illustrate the effectiveness of the proposed method.     

Multiple-model-and-neural-network-based nonlinear multivariable adaptive control

A multivariable adaptive controller feasible for implementation on distributed computer systems (DCS) is presented for a class of uncertain nonlinear multivariable discrete time systems. The adaptive controller is composed of a linear adaptive controller, a neural network nonlinear adaptive controller and a switching mechanism. The linear controller can provide boundedness of the input and output signals, and the nonlinear controller can improve the performance of the system. The purpose of using the switching mechanism is to obtain the improved system performance and stability simultaneously. Theory analysis and simulation results are presented to show the effectiveness of the proposed method.     

Robust H_∞ Controller Design for Uncertain Neutral Systems via Dynamic Observer Based Output Feedback

In this paper, the dynamic observer-based controller design for a class of neutral systems with H∞ control is considered. An observer-based output feedback is derived for systems with polytopic parameter uncertainties. This controller assures delay-dependent stabilization and H∞ norm bound attenuation from the disturbance input to the controlled output. Numerical examples are provided for illustration and comparison of the proposed conditions.     

Robust power control method for wireless sensor networks with static output feedback

This paper proposed distributed strategies for the joint control of power and data rates in a wireless sensor network. By adapting a linear state-space model to describe the network dynamics, the power controller with static output feedback is designed in the case that the transmission signal are not always available and the estimation of the unmeasured states constitutes a crucial task in the network. The existence of the power controller is formulated as the feasibility of the convex optimization problem, which can be solved via a linear matrix inequality (LMI) approach. The proposed algorithm also caters to the uncertainties in the network dynamics. Numerical examples are given to illustrate the effectiveness of the proposed methods.     

Sliding mode decoupling control of a generic hypersonic vehicle based on parametric commands

A sliding mode decoupling attitude controller based on parametric commands is proposed for a generic hypersonic vehicle(GHV). This vehicle model has fast time variability and strong coupling, is highly nonlinear, and includes uncertain parameters. The design of the controller takes these features into account.First, for the purpose of decoupling, the inner loop of the controller is designed using the dynamic inversion(DI) method. Input/output linearization is achieved using full-state feedback to globally linearize the nonlinear dynamics of selected controlled outputs. Second, to improve the robustness of the attitude control system, the sliding mode control(SMC) method is used to design the outer loop of the controller. Although the DI and SMC methods result in decoupling and robustness, there exists serious inconsistency between the commands of the attitude angles and the commands of the first-order differential of the attitude angles. To solve this problem and achieve a trade-off between dynamic response speed and attitude-tracking precision, we propose a parametric method for calculating the commands of the first-order differential of the attitude angles. Finally,simulation studies are conducted for the trimmed cruise conditions of 33.5 km altitude and Mach 15, and the responses of the vehicle to the step commands of pitch angle, yaw angle, and rolling angle are examined. The simulation studies demonstrate that the proposed controller is robust with respect to the uncertain parameters and atmospheric disturbance and meets the performance requirements of the GHV with acceptable control inputs.     

Synchronized output regulation of switching networks based on synchronization observer

This paper studies the synchronized output regulation (SOR) problem of networked dynamic systems with switching topology that is uniformly connected and leader-rooted. In these networked systems, the tracked signal or the rejected disturbance is generated by the same exosystem, and however, the state of the exosystem is only available for leader nodes. First, a synchronization observer of the exosystem is proposed in this paper to overcome the difficulty caused by the unavailable state of the exosystem for follower nodes with directed switching information flow. It is shown that the observer state will synchronize to the state of the exosystem. Then, two feedback controllers based on decentralized dynamic error and state are presented to solve this SOR problem. Furthermore, the main idea in this paper will provide a promising way for realizing the multirobot systems’ tracking and formation requirement. Numerical simulation results are presented to demonstrate the effectiveness of the theoretical results.     

Output Feedback Control for a Class of Nonlinear Systems

This paper studies the global stabilization problem by an output controller for a family of uncertain nonlinear systems satisfying some relaxed triangular-type conditions and with dynamics which may not be exactly known. Using a feedback domination design method, we explicitly construct a dynamic output compensator which globally stabilizes such an uncertain nonlinear system. The usefulness of our result is illustrated with an example.     

Decentralized load frequency control for two-area interconnected power system

This paper proposes a decentralized output feedback control scheme applied to two-area interconnected power system. The controller synthesis problem is formulated as the scaled H∞control problem and a new LMI-based algorithm is proposed to compute the decentralized controller. The proposed controller provides robustness with regard to parametric uncertainties and also attenuates bounded exogenous disturbances in the sense of L2-gain. Simulation results clearly show the effectiveness of developed decentralized output feedback control scheme.     

Piecewise output feedback control for affine systems with disturbances based on linear temporal logic specifications

In the paper,we investigate the problem of finding a piecewise output feedback control law for an uncertain affine system such that the resulting closed-loop output satisfies a desired linear temporal logic (LTL) specification.A two-level hierarchical approach is proposed to solve the problem in a triangularized output space.In the lower level,we explore whether there exists a robust output feedback control law to make the output starting in a simplex either remains in it or leaves via a specific facet.In the higher level,for the triangularization,we construct the transition system according to the reachability relationship obtained in the lower level and search for feasible paths that meet the LTL specification.The control approach is then applied to solve a motion planning problem.     

Tracking control design for nonholonomic mechanical systems with affine constraints

The trajectory tracking control is considered for nonholonomic mechanical systems with affine constraints and dynamic friction. A new state transformation is proposed to deal with affine constraints, and then an integral feedback compensation strategy is used to identify the dynamic friction. The proposed controller ensures that the output tracking errors converge to zero as t →∞.As an application, a detailed example is presented to illustrate the effectiveness of the control scheme.     

Non-fragile state feedback H-infinity control for discrete-time systems with quantized signals

This paper presents a study on the problem of non-fragile state feedback H-infinity controller design for linear discrete-time systems with quantized signals. The quantizers considered here are dynamic and time-varying. With the consideration of controller gain variations and quantized signals at the same time, a new non-fragile H-infinity control strategy is proposed with updating quantizer＇s parameters, such that the quantized closed-loop system is asymptotically stable and with a prescribed H-infinity performance bound. An example is presented to illustrate the effectiveness of the proposed control strategy.     

The output feedback control for uncertain nonholonomic systems

This paper considers the problems of almost asymptotic stabilization and global asymptotic regulation （GAR） by output feedback for a class of uncertain nonholonomic systems. By combining the nonsmooth change of coordinates and output feedback domination design together, we construct a simple linear time-varying output feedback controller, which can universally stabilize a whole family of uncertain nonholonomic systems. The simulation demonstrates the effectiveness of the proposed controller.