Dynamic Distribution Control Research Articles

Global Reachability of Heterogeneous Multiagent Systems Under Collaborative Interaction Topology and Unknown Delays

The multi-agent rendezvous problem for single- and double-integrator agents in the presence of unknown constant input and communication delays is investigated in this paper. Existing works address the rendezvous problem by incorporating negative gain(s) into the distributed consensus protocol and showing that negative gain(s) expands the reachable set beyond the initial configuration of the agents' convex hull. On the contrary, the present control protocol ensures global reachability of a network of agents with a directed communication topology having non-negative edge weights. This is accomplished with the help of a dynamic distributed control protocol, where the information exchange among agents occurs in the internal controller states. For homogeneous delays, the analytical expression of the rendezvous point confesses the non-dependency of the point with delays, which in turn signifies that rendezvous can be achieved with unknown and arbitrarily large but bounded delays. The very structure of the control protocol ensures rendezvous at any desired point, even if the input delays are heterogeneous and unknown. However, heterogeneity in communication delays has an effect on the rendezvous point, and hence, global reachability of agents can be established if these delays are exactly known. For heterogeneous multi-agent systems composed of single- and double-integrator agents, tuning of the design parameters gets simplified due to the single-integrator based internal controller structure for all agents. Numerical simulations are provided to validate the robustness of the protocol against delays.

Adaptive event-triggered dynamic distributed control of switched positive systems with switching faults

This paper designs the dynamic output-feedback controller of switched positive systems subject to switching faults using an improved adaptive event-triggering mechanism. An adaptive event-triggering condition is addressed in the form of 1-norm by virtue of the measurable outputs of distributed sensors and the corresponding error. An error-based closed-loop control system whose dynamic variable relies on a state observer is obtained. A multiple copositive Lyapunov function is constructed to deal with the positivity and stability of the systems. The matrix decomposition and linear programming approaches are used to design and compute the controller and observer gains. An improved average dwell time scheme is proposed to handle the switching faults. The contributions of this paper lie in that: (i) An adaptive event-triggering mechanism is established for switched positive systems, (ii) A framework on the fault of switching signal is constructed, and (iii) A dynamic distributed controller is proposed for the considered systems. Finally, two illustrative examples are given to verify the effectiveness of the obtained results.

Nonlinear H∞ control for synchronization of networked manipulators subject to delayed communication

In this paper, a distributed synchronization control scheme is proposed for a group of robotic manipulators with non-identical dynamics and model uncertainties subject to time-varying communication delays. By using the nonlinear H∞ control strategy, a dynamic distributed control law is developed to achieve synchronous tracking of networked robots in the joint space. Solving differential inequalities for obtaining controller parameters is a complicated task that is encountered in the nonlinear H∞ control framework, and the main feature of the suggested approach is that the parameters of the controller are found by checking the feasibility of a set of matrix inequalities. The proposed control method is implemented via simulation and its applicability is verified by illustrative results.

Dynamic Control of Braking-Force Distribution as Turning Braking

The Braking-force distribution on the left and right wheels is a key factor influencing the braking performance of vehicles at a corner. To promote the braking stability and the control ability at the turning-braking process, a new method based on the steering-angle feedforward control principle was proposed to realize dynamic braking-force distribution on the left and right wheels. A vehicle model of three wheels with two freedom degrees was established. Computer simulation of the turning-braking process with dynamic distribution control was carried out. The simulated results show that the difference between the actual yaw rate and the ideal one is significantly reduced at the period of braking being effective. It is validated that the method can effectively improve the braking stability and the control ability of vehicles at the turning-braking process.

Laboratory Test Bench for Research Network and Cloud Computing

At present moment, there is a great interest in development of information systems operating in cloud infrastructures. Generally, many of tasks remain unresolved such as tasks of optimization of large databases in a hybrid cloud infrastructure, quality of service (QoS) at different levels of cloud services, dynamic control of distribution of cloud resources in application systems and many others. Research and development of new solutions can be limited in case of using emulators or international commercial cloud services, due to the closed architecture and limited opportunities for experimentation. Article provides answers to questions on the establishment of a pilot cloud practically “at home” with the ability to adjust the width of the emulation channel and delays in data transmission. It also describes architecture and configuration of the experimental setup. The proposed modular structure can be expanded by available computing power.

Lightweight Object-Oriented Shared Variables for Cluster Computing in Java

This paper describes a lightweight yet powerful approach for writing distributed applications in Java using shared variables. Our approach, called ShareHolder, is inspired by the flexible and intuitive model of information access common to the World Wide Web. The distributed applications targeted by our approach all share a weak consistency model, similar to a user's model of accessing e-mail, bulletin boards, chat rooms, etc. on the Internet. The ShareHolder infrastructure has several advantages. Its highly object-oriented view of shared variables simplifies their initialization and configuration. A shared variable's distribution mechanism is specified through an associated configuration object, and the programmer does not need to write any extra code to implement the sharing mechanism. These configuration objects can be initialized at run-time, allowing tremendous flexibility in dynamic control of distribution of shared variables. Finally, the programmer can easily evolve a serial application into a distributed application for cluster computing by incrementally declaring certain classes as shared.

Lightweight object-oriented shared variables for distributed applications on the Internet

This paper describes a lightweight yet powerful approach for writing distributed applications using shared variables. Our approach, called S HARE H OLDER , is inspired by the flexible and intuitive model of information access common to the World Wide Web. The distributed applications targeted by our approach all share a weak consistency model and loose transaction semantics, similar to a user's model of accessing email, bulletin boards, chat rooms, etc. on the Internet. The S HARE H OLDER infrastructure has several advantages. Its highly object-oriented view of shared variables simplifies their initialization and configuration. A shared variable's distribution mechanism is specified through an associated configuration object, and the programmer does not need to write any extra code to implement the sharing mechanism. These configuration objects can be initialized at run-time, allowing tremendous flexibility in dynamic control of distribution of shared variables. Finally, the programmer can treat shared variables and local variables interchangeably, thus simplifying conversion of a serial application into a distributed application.

Using announce-listen with global events to develop distributed control systems

We specify an abstract model for dynamic distributed control systems in which the component objects make local decisions based on system-wide constraints and approximate global state. We focus on the issue of distributed resource management, exploring a solution that is both compositional and scalable because it builds global events into the Java infrastructure by exploiting its multicast facilities. © 1998 John Wiley & Sons, Ltd.