Adaptive Distributed Observer Approach Research Articles

Fixed-time leader-following consensus of multiple uncertain nonholonomic systems: An adaptive distributed observer approach

This paper discusses the fixed-time leader-following consensus problem for multiple uncertain nonholonomic systems, which are widely used in engineering models. According to our literature review, either the system is assumed to be known, or the uncertainty only contains state information, which does not meet the actual requirements. For this reason, this paper investigates more general nonholonomic systems with uncertainties driven by inputs and states. First, a fixed-time adaptive distributed observer is proposed to estimate the leader’s state and structural parameters, which ensures that the estimation errors converge to zero within a fixed time. Second, two regulator equations based on the idea of cooperative output regulation are constructed, and a novel observer-based distributed switching control law is proposed. This control law overcomes the nonholonomic constraints and appropriately relaxes the assumptions of uncertain functions in the existing references. Finally, the simulation results verify the effectiveness of the proposed control scheme.

Coordination of a Flywheel Energy Storage Matrix System: An External Model Approach

This paper studies the coordination of a heterogenous flywheel energy storage matrix system aiming at simultaneous reference power tracking and state-of-energy balancing. It is first revealed that this problem is solvable if and only if the state-of-energy of all the flywheel systems synchronize to a common time-varying manifold governed by a nonautonomous dynamic system. Next, by treating this nonautonomous dynamic system as an external model, the coordination problem can be decoupled into two separate problems, namely, the global double layer estimation problem and the local tracking problem. Then, a distributed control scheme is proposed to solve the coordination problem by integrating the adaptive distributed observer approach and the certainty equivalence control method. Comprehensive case studies are provided to show the performance of the proposed control scheme.

Output based adaptive distributed output observer for leader–follower multiagent systems

The adaptive distributed observer approach has been an effective tool for synthesizing a distributed control law for solving various control problems of leader–follower multiagent systems. However, the existing adaptive distributed observer needs to make use of the full state of the leader system. This assumption not only precludes many practical applications in which only the output of the leader system is available, but also leads to a high dimension observer. In this communique, we propose an adaptive distributed output observer which only makes use of the output of the leader system, and is thus more practical than the state based adaptive distributed observer. Moreover, the dimension and the information exchange among agents of the proposed adaptive distributed output observer can be significantly smaller than those of the state based adaptive distributed output observer.

Cooperative Output Regulation of Linear Multiagent Systems: An Event-Triggered Adaptive Distributed Observer Approach

This article investigates the cooperative output regulation problem for heterogeneous linear multiagent systems by event-triggered control, where the system matrix of the exosystem is not available to all agents. First, an event-triggered adaptive distributed observer is designed for each agent to estimate both the state and the system matrix of the exosystem. Then, a fully distributed event-triggered dynamic output feedback control law is proposed for each agent. Meanwhile, a fully distributed event-triggering mechanism is proposed such that each agent can determine when to broadcast its information to its neighbors. It is shown that with the proposed event-triggered control strategy, the cooperative output regulation problem is solved by intermittent communication in a fully distributed manner in the sense that no global information, such as the eigenvalues of the Laplacian matrix or the number of the agents, is used. It is also shown that Zeno behavior is excluded for each agent. Finally, a numerical example is given to illustrate the effectiveness of the proposed event-triggered control strategy.

Leader‐following consensus with disturbance rejection for uncertain Euler‐Lagrange systems over switching networks

SummaryIn this paper, the leader‐following consensus with disturbance rejection problem of uncertain Euler‐Lagrange systems is studied by the adaptive distributed observer approach. We first present a key lemma that guarantees the existence of an exponentially convergent adaptive distributed observer for linear leader systems without exponential growing modes over jointly connected switching and directed communication networks. This lemma also provides a specific Lyapunov function for the error dynamics of the adaptive distributed observer, which will play a crucial role in establishing one of the main results. A special case of this result where there is no disturbance will extend the existing result for a neutrally stable leader system and undirected communication networks to the case where the communication networks are directed and the leader's positional signal includes the class of ramp signals. Two examples will be given to demonstrate the effectiveness of the new results.

Leader-Following Consensus for a Class of Multiple Robot Manipulators over Switching Networks by Distributed Position Feedback Control

The leader-following consensus problem for a class of multiple robot manipulators subject to a static and connected network has been studied recently by a distributed position feedback control law. In this technical note, we will further study the same problem under a switching network satisfying the jointly connected condition. Since the switching network can be disconnected at every time instant, the approach in the literature does not apply to the problem in this technical note. To deal with the disconnected switching network, we adopt the adaptive distributed observer approach to synthesize a distributed position feedback control law. It turns out that this control law solves the leader-following consensus problem for the class of multiple robot manipulators. The effectiveness of this new result is validated by an example.

Adaptive Distributed Observer Approach for Cooperative Containment Control of Nonidentical Networks

This paper addresses the containment control problem of nonidentical networks with external disturbance via adaptive distributed observer method. We first present a formulation for containment error, which ensures all the followers’ outputs converge to the convex hull spanned by the leaders’ reference outputs. Then by using an adaptive distributed observer, the leaders’ system matrices and the states of convex hull are both estimated. Furthermore, a novel global regulate equation is designed to restrain the external disturbance, and the problem of containment control for multiagent systems is solved by a dynamic output feedback approach. Finally, some simulation results are given to illustrate the validity of the theoretical results.

A self-tuning adaptive distributed observer approach to the cooperative output regulation problem for networked multi-agent systems

ABSTRACTIn this paper, we first propose a self-tuning distributed observer for a multi-agent system, which is capable of providing the estimation of the leader's signal to various followers without assuming all the followers know the system matrix of the leader. We then further develop a novel adaptive distributed control law to solve the cooperative output regulation problem for linear heterogeneous multi-agent systems. This control law offers two advantages in that it makes less use of the information of the network as well as the information of the leader and external disturbances, and it avoids calculating the observer gain.

Leader-following Attitude Consensus of Multiple Rigid Body Systems by an Adaptive Distributed Observer Approach

The leader-following attitude consensus problem of multiple rigid body systems has been studied by the distributed observer approach. The distributed observer is able to estimate the reference signals generated by a target system under the assumption that each rigid body system knows the two system matrices of the target system. In this paper, we propose an adaptive distributed observer approach which estimates not only the state of the target system, but also the two systems matrices of the target system. Utilizing this adaptive distributed observer, we are able to solve the leader-following attitude consensus problem without assuming that each rigid body system knows the two system matrices of the target system.

The adaptive distributed observer approach to the cooperative output regulation of linear multi-agent systems

The cooperative output regulation problem of linear multi-agent systems using distributed observer approach has been solved under the assumption that each follower knows the system matrix of the leader system. To remove this assumption, in this paper, a distributed control scheme utilizing the adaptive distributed observer has been proposed, which consists of three steps. First, an adaptive distributed observer is designed to estimate both the system matrix and the state of the leader system. Second, an adaptive algorithm is developed to calculate the solutions of the regulator equations online. Third, both adaptive state feedback and adaptive measurement output feedback controllers are synthesized to solve the cooperative output regulation problem without the assumption that each follower knows the system matrix of the leader system.

The leader-following rendezvous with connectivity preservation via a self-tuning adaptive distributed observer

ABSTRACTThis paper studies the leader-following rendezvous with connectivity preservation problem for multiple double-integrator systems subject to external disturbances via a self-tuning adaptive distributed observer approach. This approach offers two advantages over the existing approach. First, it removes the existing assumption that all the followers know the system matrix of the leader system. Second, the difficult task of calculating the observer gain is avoided by the employment of the dynamic observer gain. A rigorous analysis shows that our control law is capable of maintaining the connectivity of any initial connected communication network, and achieving the asymptotic tracking and disturbance rejection for a class of leader's signals and external disturbances, which can be the algebraic sum or multiplication of any polynomial functions with any unknown coefficients and sinusoidal functions with arbitrary unknown amplitudes, initial phases, and any frequencies.