Semi-global Output Regulation Problem Research Articles

Semiglobal Periodic Event-Triggered Output Regulation for Nonlinear Multiagent Systems

This study focuses on periodic event-triggered (PET) cooperative output regulation problem for a class of nonlinear multiagent systems. The key feature of PET mechanism is that event-triggered conditions are required to be monitored only periodically. This approach is beneficial for Zeno behavior exclusion and saving of battery energy of onboard sensors. At first, new PET distributed observers are proposed to estimate the leader information. We show that the estimation error converges to zero exponentially with a known convergence rate under asynchronous PET communication. Second, a novel PET output feedback controller is designed for the underlying strict feedback nonlinear multiagent systems. Based on a state transformation technique and a local PET state observer, the cooperative semiglobal output regulation problem can be solved by the proposed new control design technique. Simulation results of multiple Lorenz systems illustrate that the developed control scheme is effective.

Cooperative Semiglobal Robust Output Regulation of Non-Introspective Nonlinear Agents With Partial Normal Form and State-Dependent High-Frequency Gain

This paper investigates cooperative semig-lobal robust output regulation problem for a class of non-introspective nonlinear multiagent systems. Each agent of this class is allowed to have a partial normal form , instead of only the conventional normal form, with a state-dependent high-frequency gain. Besides, all agents are unaccessible to the controller states of their neighbors. In this setting, if the uniform detectability assumption in the sense of [25] is satisfied, then a robust distributed regulator can be designed with the employment of a distributed nonlinear internal model and a novel distributed extended lower-power high-gain observer, such that the numerical implementation problem is solved and the regulated output of each agent asymptotically converges to the desired reference input robustly with guaranteed domain attraction.

Semi-global robust output regulation for a class of singular nonlinear systems via nonlinear internal model

ABSTRACTMost of existing results on robust output regulation problem of singular nonlinear systems are limited to local solutions. In this paper, the semi-global robust output regulation problem for a class of singular nonlinear systems is investigated by using a nonlinear internal model. Attaching a nonlinear internal model to the singular nonlinear system yields an augmented singular nonlinear system whose semi-global robust stabilisation solution leads to the solution of the semi-global robust output regulation problem of the original singular nonlinear system. The solvability conditions of the semi-global output regulation problem are established by addressing the solvability of the robust stabilisation problem of augmented singular nonlinear system. Finally, a numerical simulation example is used to illustrate the design of the semi-global regulator for the singular nonlinear systems.

Semi-global output regulation for discrete-time singular linear systems with input saturation via composite nonlinear feedback control

The semi-global output regulation problem of multi-variable discrete-time singular linear systems with input saturation is investigated in this paper. A composite nonlinear feedback control law is constructed by using a low gain feedback technique for semi-global stabilisation of discrete-time singular linear systems with input saturation. The sufficient solvability conditions of the semi-global output regulation problem by composite nonlinear feedback control are established. When the composite nonlinear feedback control law is reduced to a linear control law, the solvability conditions are an exact discrete-time counterpart of the semi-global output regulation problem of continuous-time singular linear systems. With the extra control freedom of the nonlinear part in the composite nonlinear feedback control law, the transient performance of the closed-loop system can be improved by carefully choosing the linear feedback gain and the nonlinear feedback gain. The design procedure of the composite nonlinear feedback control law and the improvement of the transient performance are illustrated by a numerical example.

Semi-global output regulation problem of switched linear multi-agent systems subject to input saturation

This paper addresses the distributed output regulation problem of switched multi-agent systems subject to input saturation. Two types of independent switching signals are considered in this work. Each agent is described by a switched linear system with an average dwell time and input saturation. The interconnection topologies are also switched subject to dwell time. Since not every agent can obtain the information of the exosystem, the distributed feedback controller is designed. An agent-dependent average dwell time method with an adjustable parameter based on algebraic Riccati equations is proposed to solve the output regulation problem. Finally, two examples are provided to illustrate the electiveness of our results.

Cooperative Semi-Global Output Regulation of Nonlinear Strict-Feedback Multi-Agent Systems With Nonidentical Relative Degrees.

In this paper, we study the cooperative semi-global output regulation problem for a class of nonlinear strict-feedback multi-agent systems, where the subsystems are assumed to have nonidentical relative degrees. We first introduce the so-called distributed internal model that converts our problem into the cooperative semi-global stabilization problem of the corresponding augmented system composed of the original multi-agent system and the internal model. We then put this augmented system into the general block lower triangular form, and develop the block semi-global backstepping technique to stabilize it. Comparing with some existing literatures, our design has removed the identical relative degree assumption, and hence applies to a much larger group of nonlinear multi-agent systems.

Semi-global output regulation for linear systems with input saturation by composite nonlinear feedback control

To improve transient performance of output response, this paper applies composite nonlinear feedback (CNF) control technique to investigate semi-global output regulation problems for linear systems with input saturation. Based on a linear state feedback control law for a semi-global output regulation problem, a state feedback CNF control law is constructed by adding a nonlinear feedback part. The extra nonlinear feedback part can be applied to improve the transient performance of the closed-loop system. Moreover, an observer is designed to construct an output feedback CNF control law that also solves the semi-global output regulation problem. The sufficient solvability condition of the semi-global output regulation problem by CNF control is the same as that by linear control, but the CNF control technique can improve the transient performance. The effectiveness of the proposed method is illustrated by a disturbance rejection problem of a translational oscillator with rotational actuator system.

Semi-global stabilization and output regulation of constrained linear plants via measurement feedback

Semi-global stabilization and output regulation of linear systems subject to state and/or input constraints have been studied in our earlier work by using state feedback. For the same problems, observer based measurement feedback control designs are the topics of this paper. High-gain observers are used in the feedback design in order to obtain accurate estimates of the state so that the constraint violation can be avoided. Due to the peaking phenomenon associated with a high-gain observer, a special saturation protection is built in the control laws to avoid possible constraint violation. The results in this paper show that the semi-global stabilization and semi-global output regulation problems for constrained linear systems are solvable via measurement feedback under solvability conditions similar to those in the state feedback.

An improvement to the low gain design for discrete-time linear systems in the presence of actuator saturation nonlinearity

A low-gain design for linear discrete-time systems subject to input saturation was recently developed to solve both semi-global stabilization and semi-global output regulation problems. This paper proposes an improvement to the low-gain design and determines controllers with the new design that achieve semi-global output regulation. The improvement is reflected in better utilization of available control capacity and consequently better closed-loop performance. Copyright © 2000 John Wiley & Sons, Ltd.

An Improvement to the Low Gain Design for Discrete-Time Linear Systems Subject to Input Saturation - Solution of Semi-Global Output Regulation Problems

A low gain design for linear discrete-time systems subject to input saturation was recently developed in (Lin and Saberi 1995a, Lin et al. 1995a, Mantri et al. 1995) to solve both semi-global stabilization and semi-global output regulation problems. This paper proposes an improvement to the low gain design and determines controllers with the new design that achieve semi-global output regulation. The improvement is reflected in better utilization of available control capacity and consequently better closed-loop performance.