Showing papers on "Contract Net Protocol published in 2006"

Dynamic shopfloor scheduling in multi-agent manufacturing systems

Abstract: This paper is on the development of an agent-based approach for the dynamic integration of the process planning and scheduling functions. In consideration of the alternative processes and alternative machines for the production of each part, the actual selection of the schedule and allocation of manufacturing resources is achieved through negotiation among the part and machine agents which represent the parts and manufacturing resources, respectively. The agents are to negotiate on a fictitious cost with the adoption of a currency function. Two MAS architectures are evaluated in this paper. One is a simple MAS architecture comprises part agents and machine agents only; the other one involves the addition of a supervisor agent to establish a hybrid-based MAS architecture. A hybrid contract net protocol is developed in the paper to support both types of MAS architectures. This new negotiation protocol enables multi-task many-to-many negotiations, it also incorporates global control into the decentralized negotiation. Simulation runs are conducted to compare the performance of the proposed MAS-based IPPS approaches and that of an evolutionary algorithm. It also shows that the hybrid-based MAS, with the introduction of supervisory control, is able to provide integrated process plan and job shop scheduling solutions with a better global performance.

SLA-Based Coordinated Superscheduling Scheme for Computational Grids

Abstract: The Service Level Agreement (SLA) based grid superscheduling approach promotes coordinated resource sharing. Superscheduling is facilitated between administratively and topologically distributed grid sites via grid schedulers such as Resource brokers and workflow engines. In this work, we present a market-based SLA coordination mechanism, based on a well known contract net protocol. The key advantages of our approach are that it allows: (i) resource owners to have finer degree of control over the resource allocation which is something that is not possible with traditional mechanisms; and (ii) superschedulers to bid for SLA contracts in the contract net, with focus on completing a job within a user specified deadline. In this work, we use simulation to show the effectiveness of our proposed approach.

A contract net based intelligent agent system for solving the reactive hoist scheduling problem

Abstract: In this article a new approach for solving the Reactive Hoist Scheduling Problem is proposed. The investigation focuses on the case where multiple hoists, sharing the same rail, are used to convey a single type of jobs along the line according to a given production sequence. It is based on two distinct, though coupled, multi-agent systems. The first system is responsible for making a decision about the input date for the next job, while the second system is concerned with the assignment of transfer operations of jobs between tanks to the hoists. These multi-agent systems use two different types of auction mechanisms to attain cooperation.

SLA-Based Coordinated Superscheduling Scheme and Performance for Computational Grids

Abstract: The Service Level Agreement~(SLA) based grid superscheduling approach promotes coordinated resource sharing. Superscheduling is facilitated between administratively and topologically distributed grid sites by grid schedulers such as Resource brokers. In this work, we present a market-based SLA coordination mechanism. We based our SLA model on a well known \emph{contract net protocol}. The key advantages of our approach are that it allows:~(i) resource owners to have finer degree of control over the resource allocation that was previously not possible through traditional mechanism; and (ii) superschedulers to bid for SLA contracts in the contract net with focus on completing the job within the user specified deadline. In this work, we use simulation to show the effectiveness of our proposed approach.

Multi-agent-based Auctions for Multi-robot Exploration

Abstract: Aiming at improving the efficiency of the multi-robot exploration, this paper presents a novel auction algorithm based on the contact net protocol of the multi-agent theory. On the basis of the analysis of the limitations of the usual auction methods to the multi-robot exploration, the contract net protocol in the multi-agent theory is presented to design a completely distributive structure for the multi-robot exploration in order to increase the tolerance and reliability of the whole system. Then an improved multi-round single-item auction algorithm is presented to assign the frontiers to the multiple robots effectively. The theoretical analysis and the simulation experiments prove that the algorithm can lead to the effective coordination of multi-robot exploration with the decreasing computation compared to the combinatorial auctions.

Platform-Level multiple sensors simulation based on multi-agent interactions

Abstract: In order to support the advanced concept technology demonstration of intelligence reconnaissance activities, multiple sensors simulation needs to provide enough detail to examine sensing dynamics on future battlefield. However, most current researches lack a modeling mechanism based on platform-level agent interactions and limit the implementation of agent-based simulations. In this paper, platform-level agent interactions based modeling and simulation technology is proposed to solve the problem. According to agent definition of mapping function from perception sequences to actions, the mapping from multiple sensors system’s members to respective agents is set up. Thus, the sensor entity agent model is designed. Moreover, sensor agent interactions model is presented to support multiple sensors simulation based on multi-agent interactions by using an improved Contract Net Protocol, where state transitions and augmented transition network are studied to represent the interactions. The established demonstration system proves the feasibility and efficiency of our model.

Atomic commit and negotiation in service oriented computing

Abstract: In this paper we investigate the relationship between two problems, related to distributed systems, that are of particular interest in the context of Service Oriented Computing: atomic commit and negotiation. We will show that there exists a rather strict interdependency between the two problems by discussing how negotiation could be expressed as an instance of the atomic commit problem, and vice versa. To this end we exploit the Contract Net Protocol, a well known negotiation protocol, that will be described by means of the asynchronous pi calculus (Pi-CNP). Besides modeling CNP we also formally describe some basic properties of the CNP protocol.

Negotiation-based task allocation in an open supply chain environment

Abstract: A supply chain is a complicated network for linking suppliers, manufacturers, and distributors. How to allocate the tasks efficiently is a key issue in supply chain management. The forming of a supply chain is dynamic in nature owing to the frequent changes of demand. This paper focuses on task allocation in the open supply chain environment. The aim is to develop a task allocation method for autonomous and self-interested agents, which have incomplete information about the open environment. The proposed mechanism is based on an automatic negotiation approach, which is used to allocate tasks by negotiating among the manager-to-bidder and bidder-to-bidder. The modification of contract net protocol (CNP) for manager-bidder and the protocol of the stochastic offer are introduced, and the relevant negotiation algorithms are also presented. The proposed method is a dynamic method for task allocation, which is applicable to the open environment without a central authority and permits some degree of reconfiguration. Reconfiguration is useful in dispatching new tasks or handling resource failures.

Integrated Mission Specification and Task Allocation for Robot Teams - Part 2: Testing and Evaluation

Abstract: : This work presents the evaluation of two mission specification and task allocation architectures. These architectures, described in part 1 of this paper, present novel means with which to integrate a case-based reasoning (CBR) mission planner with contract net protocol (CNP) based task allocation. In the first design, the CBR and runtime-CNP architecture, the case-based mission planner generates mission plans that support necessary behaviors for CNP-based task allocation and execution. In the second design, the CBR and premission-CNP architecture, task allocation takes place during mission specification. The results of an empirical evaluation of the CBR and runtime-CNP across three naval scenarios is described. Finally, we briefly describe an earlier usability evaluation of the CBR and premission-CNP architecture using goals, operators, methods, and selection rules modeling.

DOC: The Degree of Credibility Model in Contract Net Protocol

Abstract: The Degree of Credibility(DOC)model is proposed in the Contract Net Protocol(CNP)for the non-cooperative multi-agent system. In order to maximize their profiles, the self-interested agents may embellish their bids and delude their manager to get more bids, even if they cannot accomplish the tasks on time. With the DOC model, when the manager evaluates the bids from the contractors, it will make a decision on the contractors’ historical credibility, by which can decrease the negation times and enhance the task completion quality. To show the properties of the DOC model, we have implemented the agent interaction processes using CNP on the JATLite platform. The experimental results indicate that the DOC model can improve the performance of the system while preserving the task completion quality, especially in situation of large amount of tasks.

A Novel Multi-agent Based Complex Process Control System and Its Application

Abstract: Complex process control systems need a hybrid control mode, which combines hierarchical structure with decentralized control units. Autonomy of agents and cooperation capability between agents in multi-agent system provide basis for realization of the hybrid control mode. A novel multi-agent based complex process control system is proposed. Semantic representation of a control-agent is presented utilizing agent-oriented programming. A novel temporal logic analysis of a control-agent is proposed using Petri nets. Collaboration relationships among control-agents are analyzed based on extended contract net protocol aiming at the lack of reference [1]. Taken pressure control of recycled gas with complicated disturbances as an application, five kinds of control-agents are derived from control-agent. Reachable marking tree and different transition of each derived control-agent are analyzed in detail. Actual running effect indicates multi-agent based hybrid control mode is rationality and flexible. Temporal logic analysis based on Petri nets ensures the reachability of the systems. Extended contract net protocol provides a reasonable realization for collaboration relationships.

A Self-adaptive Knowledge Based Dynamic Scheduling Decision Mechanism

Abstract: Through the interrelated concept of the shop floor production, this paper constructs a scheduling decision system based on the Contract Net Protocol, and gives five attributes of resource agent and corresponding task: time, cost, quality, load and priority. Using the fuzzy set and rough set, the classified knowledge of the attribute is generated, and is used as the states criteria in the Q-learning. To initialize Q value of the decision attribute, we collect the knowledge from experts. The Q-learning algorithm and initial parameter values are presented in our dynamic scheduling decision system. Based on the algorithmic analysis, we demonstrate its convergence and credibility. Applying this algorithm, the system will explore the more useful scheduling decisions in the changeful environment continuously, and update knowledge of the system, thus it will avoid the subjectivity and invariance of the expert knowledge. As a result, the knowledge-based dynamic scheduling decision system will be more flexible, and adjust itself according to the dynamic environment continuously.

Performance evaluation of an auction-based job allocation model for small- and medium-sized enterprises

Abstract: This paper extends the application scope of a previously developed auction-based shop floor control model to the enterprise level and evaluates its performance for the coordination and collaboration of spatially distributed Small- and Medium-sized Enterprises (SMEs). The model uses the contract net protocol to facilitate the negotiation process among SMEs and consists of two main components: task proposal formulation and bid formulation. An agent-based simulation environment is developed in ProModel to evaluate the impact of two negotiation factors and due date slack of tasks on tardiness, earliness and absolute due date deviation of tasks. A mixed-level factorial Design of Experiments (DOE) is carried out by considering different levels of α, β and K, and the results of the simulation study are analysed using Analysis of Variance (ANOVA) in Minitab. This study shows that the auction-based model is effective for the task allocation among SMEs, yet it is necessary to fine-tune the negotiation factors based on the due-date-related performance measures.

A PSO and Simulated Annealing Hybrid Algorithm to Task Allocation Problem for Holonic Manufacturing System

Abstract: This paper focuses on the dynamic reconfiguration and task optimization of holonic manufacturing systems (HMS). The concept of dynamic virtual clustering is extended to the control process of a holarchy or holonic organization. The mediator-based dynamic virtual clustering mechanism is presented firstly. Then a negotiation strategy based on the contract net protocol is proposed for cooperative action among holons. Finally, a hybrid algorithm based on PSO and simulated annealing for holon task allocation is described to support the optimum organization of a holarchy. PSO employs a collaborative population-based search, which is inspired by the social behavior of bird flocking. It combines local search (by self experience) and global search (by neighboring experience), possessing high search efficiency. SA employs certain probability to avoid becoming trapped in a local optimum and the search process can be controlled by the cooling schedule. The hybrid algorithm combines the high speed of PSO with the powerful ability to avoid being trapped in local minimum of SA. We compare the PSO algorithm to both GA and SA models, the simulation results show that the proposed model and algorithm are effective

Cognitive Agents for Modeling Military Command Entities

Abstract: In order to support the advanced concept technology demonstration of military command system application on future information battlefield, multi-agent-oriented modeling technology is applied in this paper. Based on description of the principles, requirements and process of modeling, mappings from military command system's members, i.e., command entities to respective cognitive agents, are set up, by which the distributed cognitive agents system is designed to represent military command behaviors. A modified contract net protocol approach is proposed to analyze the interaction of command entity agents. The work of this paper is illustrated by a demonstration system and the obtained simulation results show the effectiveness of our approach and model.

Distributed Cooperative Planning for multiple UAVs Based on Agent Negotiation

Abstract: Aiming to overcome the limitations of centralized planning methods, distributed planning approaches based on agent negotiation are proposed for a team of unmanned aerial vehicles (UAVs) to execute tasks cooperatively. To solve the problem, a two-stage approach is presented. Firstly, contract net protocol is applied, so that UAVs plan independently and negotiate mutually to realize dynamic task allocation. By integrating several types of contracts to work together, task allocation in complex battlefield environment can be solved more efficiently. Secondly, based on the detection of the relations among tasks, a novel compensatory negotiation mechanism is presented to coordinate the task execution process of UAVs whose tasks are correlative. Thus, UAVs can achieve their tasks more effectively with the assistance of others. Finally, simulation results demonstrate the validity of the approach proposed.

Possibilistic Petri Nets as a Basis for CNP-Based Bidding Mechanism

Abstract: As the number of agents increases rapidly on the Internet, discovering appropriate service agents with required capabilities for request agents becomes a crucial issue in multi-agent systems. Two major discovering approaches have been developed: centralized matchmaking approaches and distributed bidding approaches. However, the former approaches may suffer the problem of middle agent overload and can not reflect the dynamic characteristic of agent capabilities, while the later has the problems of the overhead for maintaining contact lists of service agents in each request agent and sending ineffective CFP messages to non-qualified service agents. To address the above problems, in this paper, we propose a CNP-based bidding mechanism based on Possibilistic Petri Nets that facilitates request agents to find preferred service agents. Moreover, our mechanism provides more flexible match that not only supports exact match but also takes the degree of satisfaction into account.

Research the Strategy of Filtering the “Acquaintances” Based on Contract Net Protocol

Abstract: We deeply analyze the disadvantages of contract net protocol and introduce the strategy of filtering the “acquaintances” based on the contract net protocol. The strategy reduces manager agent’s workload that bids to apply for by filtering the bidders reasonably.At the same time the network correspondence quantity is lowered and the efficiency of Multi-agent System is raised.

Research on Cooperation of Multiple Agent Based on Contract-Net Model

Abstract: In open environments such as the Internet agents from heterogeneous sources could exist and interact to accomplish joint activities.The general Contract Net Protocol model which works on bids invitation between a Manager agent and Contractor agents can successfully realize the cooperation among agents.But it also faces many problems such as the high network traffic and low adaptation to the changes of the contractors' capacity and load.So in this paper,the concepts of grade field and timing consumption are put forward and introduced into the general contract net protocol and a new model of grade field and timing consumption contract net model is made.By dividing three different grades subfields according to the capability and success rate in all the service agents,the intercooperation of the service agents is limited in grade field 1.The theoritic analysis and the experiments show that this new model can reduce the searching range and lighten the network.traffic.Furthermore it can balance the load of the contractors.

Research and application of production planning model based on multi-agent

Abstract: Integrating multi-agent system, the plan assignment model base on multi-agent is proposed to solve the assignment problem of production plan among some parallel shops with geographic distribution. The advantages and disadvantages of Contract Net Protocol (CNP) applied in production plan was analyzed, and the improved negotiation mechanism of CNP is developed. Through the negotiation of Management Agent, Shop Agent and Plan Agent, it realized the optimization assignment of production plan. Finally, the simulation example shows that whole interaction of multi-agent and proves the validity of the model.